CWT Bibliography

Journal Articles

Demi, LM, Benstead, JP, Rosemond, AD, Maerz, JC. Experimental N and P additions alter stream macroinvertebrate community composition via taxon-level responses to shifts in detrital resource stoichiometry. Funct Ecol. 2019; 00: 1– 13. https://doi.org/10.1111/1365-2435.13289

Abstract
1. Increases in nitrogen (N) and phosphorus (P) availability are changing animal communities, partly by altering stoichiometric imbalances between consumers and their food. Testing relationships between resource stoichiometry and consumer assemblage structure requires ecosystem-level manipulations that have been lacking to date. 2. We analysed patterns of macroinvertebrate community composition in five detritus- based headwater streams subject to experimental whole-stream N and P additions that spanned a steep gradient in dissolved N:P ratio (2:1, 8:1, 16:1, 32:1, 128:1) over 2 years, following a 1-year pre-treatment period. 3. We predicted that shifts in leaf litter stoichiometry would drive overall patterns of community composition via greater responses of shredders to enrichment than other taxa, as shredders dominate primary consumer biomass and experience larger consumer–resource elemental imbalances than other functional groups in stream ecosystems. Specifically, we expected litter C:P to be a significant predictor of shredder biomass given the greater relative imbalances between shredder and litter C:P than C:N. Finally, we tested whether shredder responses to enrichment were related to other taxon-level traits, including body size and stoichiometry, larval life span and growth rate. 4. Whole-community composition shifted similarly across the five streams after enrichment, largely driven by increased shredder and predator biomass. These shifts were limited to the autumn/winter seasons and related to decreased leaf litter C:P, highlighting important links between the quality of seasonal litter subsidies and community phenology. 5. Among 10 taxa that drove structural shifts, two declined while other taxa from the same functional/taxonomic groups responded positively, suggesting that specific life-history traits may determine sensitivity to enrichment. 6. Increases in total shredder biomass, and in biomass of several common shredders, were associated with lower litter C:P. Body C:P did not predict shredder response to enrichment. However, weak negative relationships between shredder response and body size, and larval life span, suggest that small-bodied and short-lived taxa may be more responsive to shifting resource stoichiometry.

Abbott, D.T., and D.A. Crossley Jr. 1982. Woody litter decomposition following clear-cutting. Ecology 63: 35-42.

Abstract
Unconfined Quercus prinus woody litter of three size classes (0-1, 1-3, and 3-5 cm diameter) was placed on forest floors of a control hardwood watershed and on mesic and xeric sites of a clear-cut watershed at Coweeta. Exponential decay coefficients for mass loss on the control were .1524, .1728, and .0912 /yr for 0-1, 1-3, and 3-5 cm branches, respectively. Coefficients for 0-1, 1-3, and 3-5 cm branches were .1752, .0756, and .1644 /yr on the mesic site and .0456, .0948, and .0377 /yr on the xeric site. The effect of site differences on decomposition rate was greater than the effect of diameter, although an inverse relationship between diameter and decay coefficient is suggested. Time in the field, temperature, moisture, and microarthropod abundance also appeared to influence decomposition rate.

Abbott, D.T., T.R. Seastedt, and D.A. Crossley Jr. 1980. The abundance, distribution and effects of clear-cutting on Cryptostigmata in the southern Appalachians. Environmental Entomology 9: 618-623.

Abstract
Oribatid mites were sampled from deep soil, soil cores, litter bags, and woody litter on a clearcut and adjacent control hardwood watershed at Coweeta. The inclusion of woody litter and deep soil samples caused the total number of genera found to reach 72, as opposed to the 37-42 genera range reported in other studies. The more common genera were assigned to three habitat types based on stratification data. The fauna was similar to those of other holarctic study sites. Sampling a greater variety of habitat types yielded a richer fauna than intensive sampling of a few habitat types. Clearcutting caused a reduction in numbers and a shift in faunal dominance. This effect is attributed to temperature-humidity phenomena rather than to food availability.

Aber, J.D., A. Magill, S.G. McNulty, R.D. Boone, K.J. Nadelhoffer, M. Downs, and R. Hallett. 1995. Forest biogeochemistry and primary production altered by nitrogen saturation. Water, Air and Soil Pollution. 85: 1665-1670.

Abstract
Results from four intensive site-level manipulations and one extensive field survey in northern temperate and boreal forests show a consistent set of responses to chronic N additions. These include 1) initial and often large increase in net N mineralization followed by decreases, 2) increases in net nitrification, 3) increases in N concentration in foliage, and 4) decreased Mg:N and Ca:Al ratios, and declining tree growth and vigor in all evergreen stands. These results are synthesized into a set of proposed summary relationships that define the temporal pattern of responses of N-limited systems to N additions.

Adams, M., Knoepp, J.D. and Webster, J.R. 2014. Inorganic nitrogen retention by watersheds at Fernow Experimental Forest and Coweeta Hydrologic Laboratory. Soil Science Society of America Journal. (DOI: 10.2136/sssaj2013.11.0463nafsc)

Abstract
Because elevated N loading can impair both terrestrial and aquatic ecosystems, understanding the abiotic and biotic controls over retention and export of dissolved inorganic N (DIN) is crucial. Long-term research has been conducted on experimental watersheds at two U.S. Forest Service experimental forests in the Appalachian region: Fernow Experimental Forest (FEF) in West Virginia and Coweeta Hydrologic Laboratory (CHL) in North Carolina. While similar in vegetation and research history, FEF and CHL differ in climate, historic DIN deposition, and soils. We evaluated long- term patterns of DIN inputs and exports from three watersheds at each location with similar treatments including clear-cut harvest, conversion to conifer plantation (Norway spruce [ Picea abies (L.) H. Karst.] at FEF and white pine [ Pinus strobus L.] at CHL), as well as reference watersheds. We examined DIN export and retention in these watersheds, comparing treated and reference watersheds within each experimental forest and comparing similarly treated watersheds between the experimental forests. Despite current similar levels of N deposition, stream water DIN concentrations and exports were generally greater at FEF by almost an order of magnitude. We found differences between FEF and CHL in stream DIN concentrations, watershed export, and retention of DIN inputs not only in the untreated reference watersheds but also in the watersheds with similar disturbance treatment. We hypothesize that these differences are the result of site and vegetation differences as well as site history including long-term patterns of DIN deposition. We document the switch from biogeochemical to hydrologic controls that occurred when N availability exceeded N immobilization, due to either N deposition or biological N inputs.

Adams, R.K., and J.A. Spotila. 2005. The form and function of headwater streams based on field and modeling investigations in the Southern Appalachian Mountains. Earth Surface Processes and Landforms. 30: 1521-1546.

Abstract
Headwater streams drain the majority of most landscapes, yet less is known about their morphology and sediment transport processes than for lowland rivers. We have studied headwater channel form, discharge and erosive power in the humid, moderate-relief Valley and Ridge and Blue Ridge provinces of the Appalachian Mountains. Field observations from nine headwater (<2 km2 drainage area), mixed bedrockvalluvial channels in a variety of boundary conditions demonstrate variation with respect to slope-area channel initiation, basic morphology, slope distribution, hydraulic geometry, substrate grain size and role of woody debris. These channels display only some of the typical downstream trends expected of larger, lowland rivers. Variations are controlled mainly by differences in bedrock resistance, from the formation level down to short-wavelength, outcrop-scale variations. Hydrologic modeling on these ungauged channels estimates the recurrence of channel-filling discharge and its ability to erode the channel bed. Two-year recurrence discharge is generally larger and closer to bankfull height in the Valley and Ridge, due to low soil infiltration capacity. Discharge that fills the channel to its surveyed bankfull form is variable, generally exceeding two-year flows at small drainage areas (<0+5 km2) and being exceeded by them at greater drainage areas. This suggests bankfull is not controlled by the same recurrence storm throughout a channel or physiographic region. Stream power and relative competence are also variable. These heterogeneities contrast relations observed in larger streams and illustrate the sensitivity of headwater channels to local knickpoints of resistant bedrock and armoring of channels by influx of coarse debris from hillslopes. The general lack of predictable trends or functional relationships among hydraulic variables and the close coupling of channel form and function with local boundary conditions indicate that headwater streams pose a significant challenge to landscape evolution modeling.

Addington, R.N., L.A. Donovan, R.J. Mitchell, J.M. Vose, S.D. Pecot, S.B. Jack, U.G. Hacke, J.S. Sperry, and R. Oren. 2006. Adjustments in hydraulic architecture of Pinus palustris maintain similar stomatal conductance in xeric and mesic habitats. Plant Cell and Environment. 29(4): 535-545.

Abstract
We investigated relationships between whole-tree hydraulic architecture and stomatal conductance in Pinus palustris Mill. (longleaf pine) across habitats that differed in soil properties and habitat structure. Trees occupying a xeric habitat (characterized by sandy, well-drained soils, higher nitrogen availability and lower overstory tree density) were shorter in stature and had lower sapwood-to-leaf area ratio (AS:AL) than trees in a mesic habitat. The soil-leaf water potential gradient (?S v ?L) and leaf-specific hydraulic conductance (?S) of roots. Leaf and canopy stomatal conductance (gs and Gs, respectively) were also similar between sites, and they tended to be somewhat higher at the xeric site during morning hours when vapour pressure deficit (D) was low A hydraulic model incorporating tree height, AS:AL and ?S v ?L accurately described the observed variation in individual tree GSref (GS at D = 1kPa) across sites and indicated that tree height was an important determinant of GSref across sites. This, combined with a 42% higher root-to-leaf area ratio (AR:AL) at the xeric site, suggests that xeric site trees are hydraulically well equipped to realize equal v and sometimes higher v potential for conductance compared with trees on mesic sites. However, a slightly more sensitive stomatal closure response to increasing D observed in xeric site trees suggests the potential for higher conductance many only be reached when D is low and when the capacity of the hydraulic system to supply water to foliage is not greatly challenged.

Albright, T. P., D. P. Anderson. N. S. Keuler. S. M. Pearson. M. G. Turner. 2009. The spatial legacy of introduction: Celastrus orbiculatus in the southern Appalachians, USA. Journal of Applied Ecology, 46:1229-1238

Abstract
1. A variety of abiotic, biotic, human and historic variables related to environmental suitability and propagule pressure determine the distribution of invasive plants in a landscape. Understanding the role of these variables for invasive species is challenging because environmental variables are often correlated, many invaders have broad ecological niches, and invasive distributions are often highly dynamic. 2. We examined the role of environmental variables at multiple spatial scales on the distribution of an invasive vine Celastrus orbiculatus (Celastraceae) in the southern Appalachians, USA. Using existing and newly collected occurrence data, we constructed spatial generalized linear mixed models of C. orbiculatus occurrence in the whole region as well as the areas nearest (established zone) and farthest (pioneer zone) fromthe purported introduction locus. 3. For the entire study region, distance from the introduction locus and terrain slope were negatively related to the probability of occurrence of C. orbiculatus. The model was highly discriminatory, with an area under the receiver-operating characteristic curve of 0Æ91. 4. Distance from introduction locus and slope were also important in the models for the pioneer and established zones respectively. 5. The pioneer zone model also indicated a negative relationship with elevation and the established zone model indicated a positive relationship with local topographic position, but these models were less discriminatory. 6. Synthesis and applications. Distance from introduction locus was the most powerful variable examined, suggesting anenduringlegacyof introductionfor the currentdistributionofC. orbiculatus. The varying results in the three zones highlight the importance of accounting for both introduction history and uneven propagule pressure in studies of observed invasive species distributions. The observed relationships with distance and elevation suggest that land managers should prepare for C. orbiculatus to expandits distribution in the regionover timeandwith awarming climate.

Alexander, E.B. 1988. Rates of soil formations: Implications for soil-loss tolerance. Soil Science 45(1): 37-45.

Abstract
Land managers are concerned with maintaining crop, forest, and range production. If erosion losses from moderately deep or shallow soils occur faster than the soil is replenished by weathering from underlying bedrock or consolidated sediments, productivity will decline. Therefore, rates of soil formationf can be considered constraints on tolerable soil losses from relatively shallow soils; their longterm soil-loss tolerances can be equated with their rates of formation from bedrock or consolidated sediments. There are few data for determining rates of soil formation, however. Data from small, nonagricultural watershed studies in which the inputs and outputs of silica and the major cations have been measured can be utilized for this purpose. Rates of soil formation, based on these data from 18 watersheds with noncarbonate lithologies, range from 0.02 to 1.9 Mg/ha yr. The rates are most highly dependent on (1) the volume of runoff water and (2) the soil-to-rock ratio, where this ratio is a mass of soil divided by the mass of bedrock weathered to produce that mass of soil. An equation developed to predict rates of soil formation from these two parameters has a very high coefficient of determination, R2 = 0.94.

Alexander, E.B. 1989. Response to the letter to the editor. Soil Science. 148(1): 75-76.

Abstract
Alexander writes in response to a letter to the editor which had been written by Vebel and which critiqued Alexander's applicaton of the approximate form of Barth's equation. Alexander expresses disappointment in misinterpretations and misrepresentations in Vebel's discussion of statements in Alexander's article.

Alexei, S., and M. Pridnia. 1995. A comparison of the southern Appalachian (U.S.A.) and southwestern Caucasus (Russia) forests: influences of historical events and present environment. Journal of Biogeochemistry. 22: 1073-1081.

Abstract
The Southern Appalachian (North America) and Southwester Caucasus (Eastern Europe) forests have a common origin, the warm-temperate Tertiary forests, but a different history of development. The Southwestern Caucasus forests experienced a dramatic species loss at the Tertiary, while Tertiary flora of the Appalachian region was preserved without major changes. Certain similarities and differences between the flora and vegetation of the Southern Appalachians and Southwestern Caucasus can be attributed to the Tertiary and post-Tertiary history of both regions. The similarities include the species-to-genus and species-to-families ratios and the floristic composition. The differences include taxonomic diversity and percentage of tree taxa.

Allen, C.J., A. Heyes. 1998. A preliminary assessment of wet deposition and episodic transport of total and methyl metcury from low order Blue Ridge watersheds, S.E. U.S.A. Water, Air, and Soil Pollution. 105: 573-592.

Abstract
Results from a preliminary sampling program designed to investigate total (THg) and methyl Hg (MeHg) deposition, cycling and transport at the Coweeta Hydrologic Laboratory western North Carolina are presented. Wet deposition samples were collected in June and July 1994 and throughfall, seep and streamwaters were intensively collected during and after a rainfall event in June 1994. All water samples were collected using ultra clean trace sampling protocol. Low elevation Watershed 18 streamwater THg concentrations peaked with discharge, increasing 6 fold to 9 ng L-1. High elevation Watershed 27 which received less than one half the precipitation Watershed 18 received during the event, exhibited THg concentrations only 1.3 times over base flow conditions. Methyl Hg concentrations remained near detection limits in both streams. Dissolved MeHg concentrations were higher in shallow seep, throughfall and precipitation than streamwaters. Initial estimates of annual THg and MeHg deposition and transport indicate >90% retention of THg and a >80% retention or demethylation of wet deposition MeHg is occurring in these low order watersheds.

Allen, Karen E. and Rebecca Moore. 2016. Moving beyond the exchange value in the nonmarket valuation of ecosystem services. Ecosystem Services 18:78-86. doi:10.1016/j.ecoser.2016.02.002.

Abstract
There has been much discussion across the ecosystem services literature as to the role of economic valuation in identifying ecosystem service values and shaping policy. This article demonstrates a non-typical use of a nonmarket valuation technique known as the stated choice experiment (CE) for understanding a range of public preferences for stream-related ecosystem services in Macon County, NC. The experiment was carried out as part of the National Science Foundation funded Coweeta Long Term Ecological Research initiative, and it reflects an interdisciplinary attempt to produce knowledge regarding ecosystem service values that is of relevance to policy makers. The CE uses a split-sample design to test for the impact of mechanism of program implementation on respondent preferences and demonstrate a range of public willingness to pay (WTP) for stream health improvements. Responses are analyzed with a latent class logit and the results show that altering the mechanism of program implementation changes the latent class composition. Results also demonstrate consistent preferences for certain attributes of stream health, but WTP for ecosystem service provisioning varies widely with proposed program implementation. The use of the CE in this research demonstrates the flexibility of the tool for combining with interdisciplinary knowledge, as well as the usefulness of information provided by nonmarket valuation techniques for informing policy design.

Alverson, A.J., and G.W. Courtney. 2001. Niche overlap of sympatric Blepharicera larvae (Diptera: Blephariceridae) from the southern Appalachian Mountains. Journal of the North American Benthological Society. 20(4): 564-581.

Abstract
The southern Appalachian Mountains are home to the greatest diversity of Blepharicera (Diptera) in North America, with 13 Blepharicera Macquart species inhabiting the region. Sympatric Blepharicera species seem to occupy a common ecological niche, in contradiction to the competitive exclusion principle. Instar IV Blepharicera larvae were studied to determine whether dietary differences facilitate coexistence of sympatric species. Diatom assemblage of Blepharicera diets, total diatom biovolume ingested, and similarity between diatom assemblage of larval diets and the forage base were examined. Dietary characteristics were compared among Blepharicera species within and between discrete microhabitats at 3 sites in southern Appalachia. Data showed broad dietary overlap among species that co-occurred in the same microhabitat and strong microhabitat effects on larval dietary assemblages. In addition, several species ingested disproportionately greater biovolumes of small adnate and prostrate diatom species compared to their availability on the substratum. Sympatric Blepharicera species may not partition food resources where spatial overlap is most acute.

Amos, H.M., C.F. Miniat, J. Lynch, J. Compton, P.H. Templer, L.A. Sprague, D. Shaw, D. Burns, A. Rea, D. Whitfall, L. Myles, D. Gay, M. Nilles, J. Walker, A.K. Rose, J. Bales, J. Deacon, and R. Pouyat. 2018. What Goes Up Must Come Down: Integrating Air and Water Quality Monitoring for Nutrients. Environmental Science & Technology 52(20): pp 11441-11448.

Abstract
Excess nitrogen and phosphorus (“nutrients”) loadings continue to affect ecosystem function and human health across the U.S. Our ability to connect atmospheric inputs of nutrients to aquatic end points remains limited due to uncoupled air and water quality monitoring. Where connections exist, the information provides insights about source apportionment, trends, risk to sensitive ecosystems, and efficacy of pollution reduction efforts. We examine several issues driving the need for better integrated monitoring, including: coastal eutrophication, urban hotspots of deposition, a shift from oxidized to reduced nitrogen deposition, and the disappearance of pristine lakes. Successful coordination requires consistent data reporting; collocating deposition and water quality monitoring; improving phosphorus deposition measurements; and filling coverage gaps in urban corridors, agricultural areas, undeveloped watersheds, and coastal zones.

Amy D. Rosemond, Jonathan P. Benstead, Phillip M. Bumpers, Vladislav Gulis, John S. Kominoski, David W. P. Manning, Keller Suberkropp, and J. Bruce Wallace. 2015. Experimental nutrient additions accelerate terrestrial carbon loss from stream ecosystems. Science. 347:1142-1145. DOI:10.1126/science.aaa1958.

Abstract
Nutrient pollution of freshwater ecosystems results in predictable increases in carbon (C) sequestration by algae. Tests of nutrient enrichment on the fates of terrestrial organic C, which supports riverine food webs and is a source of CO2, are lacking. Using whole-stream nitrogen (N) and phosphorus (P) additions spanning the equivalent of 27 years, we found that average terrestrial organic C residence time was reduced by ~50% as compared to reference conditions as a result of nutrient pollution. Annual inputs of terrestrial organic C were rapidly depleted via release of detrital food webs from N and P co-limitation. This magnitude of terrestrial C loss can potentially exceed predicted algal C gains with nutrient enrichment across large parts of river networks, diminishing associated ecosystem services.

Anderson, D.P., Turner, M.G., Pearson, S.M., Albright, T.P., Peet, R.K. and Wieben, A. 2013. Predicting Microstegium vimineum invasion in natural plant communities of the southern Blue Ridge Mountains, USA. Biological Invasions. 15(6):1217-1230. (DOI: 10.1007/s10530-012-0361-3)

Abstract
Shade-tolerant non-native invasive plant species may make deep incursions into natural plant communities, but detecting such species is challenging because occurrences are often sparse. We developed Bayesian models of the distribution of Microstegium vimineum in natural plant communities of the southern Blue Ridge Mountains, USA to address three objectives: (1) to assess local and landscape factors that influence the probability of presence of M. vimineum; (2) to quantify the spatial covariance error structure in occurrence that was not accounted for by the environmental variables; and (3) to synthesize our results with previous findings to make inference on the spatial attributes of the invasion process. Natural plant communities surrounded by areas with high human activity and low forest cover were at highest risk of M. vimineum invasion. The probability of M. vimineum presence also increased with increasing native species richness and soil pH, and decreasing basal area of ericaceous shrubs. After accounting for environmental covariates, evaluation of the spatial covariance error structure revealed that M. vimineum is invading the landscape by a hierarchical process. Infrequent long distance dispersal events result in new nascent subpopulations that then spread via intermediate- and short-distance dispersal, resulting in 3-km spatial aggregation pattern of sub-populations. Containment or minimisation of its impact on native plant communities will be contingent on understanding how M. vimineum can be prevented from colonizing new suitable habitats. The hierarchical invasion process proposed here provides a framework to organise and focus research and management efforts.

Anderson, M. 1989. Forest hydrology and ecology at Coweeta Forestry 62(2).

Abstract
A review of the Coweeta Symposium volume.

Andre, H., X. Ducarme, J. Anderson, D. Crossley Jr., H. Koehler, M. Paoletti, D. Walter, and P. Lebrun. 2001. Rebuttal letter re: Skilled eyes are needed to go studying the richness for the soil.Nature. 409(761)

Abstract
Rebuttal Letter re: Copley; 2000. Journal Nature. 406, 452.

Anglin, Zachard W., Grossman, Gary D. 2013. Microhabitat use by southern brook trout (Salvelinus fontinalis) in a headwater North Carolina stream. Ecology of Freshwater Fish 22(4):567-577. https://doi.org/10.1111/eff.12059.

Abstract
Brook trout are the one of the only Salvelinus species native to eastern North America and range from Canada to Georgia. Very little is known, however, about the ecology of the southern form of this species. We quantified microhabitat use of southern brook trout in Ball Creek NC, a third-order stream, during six seasonal samples (summer 2010, autumn 2010, spring 2011, summer 2011, autumn 2011 and spring 2012). In general, trout preferentially occupied deeper microhabitats with lower mean velocities and higher amounts of erosional substrata than were randomly available. Older trout (1+ and 2+) occupied deeper microhabitats with lower mean velocities than yearling trout. These microhabitats typically represent ‘plunge pools’. Southern brook trout also occupied focal point velocities that were statistically indistinguishable from optimal velocities calculated for rainbow trout in the same system and thus may chose microhabitats that maximise net energy gain. Southern brook trout are found in isolated populations, and management strategies should focus on the preservation of plunge pool habitat for conservation of this subspecies.

April, R., and D. Keller. 1990. Mineralogy of the rhizosphere in forestsoils of the eastern United States. Biogeochemistry 9: 1-18.

Abstract
Chemical and mineralogical studies of forest soils from six sites in the northeastern and southeastern United States, including the two Integrated Forestsites at Coweeta, indicate that soil in the immediate vicinity of roots show marked differences in physical characteristics, mineralogy and weathering compared to the bulk of the forest soil. Mineral grains are affected mechanically, chemically and mineralogically by the invading root bodies. The edges of mineral grains abutting root surfaces were significantly more fractured. Chemical interactions between roots and minerals included precipitation of amorphous aluminum oxides, opaline and amorphous silica, and calcium oxalate within the cells of mature roots and possible preferential dissolution of mineral grains adjacent to root bodies.

Ardon, M., Pringle, C.M., Eggert, S.L. 2009. Does leaf chemistry differentially affect breakdown in tropical vs temperate streams? Importance of standardized analytical techniques to measure leaf chemistry. North American Benthological Society, 28(2):440-

Abstract
Comparisons of the effects of leaf litter chemistry on leaf breakdown rates in tropical vs temperate streams are hindered by incompatibility among studies and across sites of analytical methods used to measure leaf chemistry. We used standardized analytical techniques to measure chemistry and breakdown rate of leaves from common riparian tree species at 2 sites, 1 tropical and 1 temperate, where a relatively large amount of information is available on litter chemistry and breakdown rates in streams (La Selva Biological Station, Costa Rica, and Coweeta Hydrologic Laboratory, North Carolina, USA). We selected 8 common riparian tree species from La Selva and 7 from Coweeta that spanned the range of chemistries of leaf litter naturally entering streams at each site. We predicted that concentrations of secondary compounds would be higher in the tropical species than in the temperate species and that high concentrations of condensed tannins would decrease breakdown rates in both sites. Contrary to our predictions, mean concentration of condensed tannins was significantly greater (2.63, p , 0.001) for species at Coweeta than for species at La Selva. Concentration of condensed tannins was negatively correlated with breakdown rate among Coweeta species (r=-0.80), not among La Selva species, and negatively correlated when the 2 sites were combined (r=-0.53). Concentrations of structural compounds were strongly correlated with breakdown rate at both sites (Coweeta species, lignin r=-0.94, cellulose r=-0.77; La Selva species, cellulose r=-0.78, C r=-0.73). The chemistries of 8 riparian species from La Selva and 7 riparian species from Coweeta were not as different as expected. Our results underline the importance of standardized analytical techniques when making cross-site comparisons of leaf chemistry.

Argerich, A., S.L. Johnson, S.D. Sebestyen, C.C. Rhoades, E. Greathouse, J.D. Knoepp, M.B. Adams, G.E. Likens, J.L. Campbell, W.H. McDowell, F.N. Scatena and G.G. Ice. Trends in stream nitrogen concentrations for forested reference catchments across the USA. 2013. Environmental Research Letters 8:014039 (8pp).

Abstract
To examine whether stream nitrogen concentrations in forested reference catchments have changed over time and if patterns were consistent across the USA, we synthesized up to 44 yr of data collected from 22 catchments at seven USDA Forest Service Experimental Forests. Trends in stream nitrogen presented high spatial variability both among catchments at a site and among sites across the USA. We found both increasing and decreasing trends in monthly flow-weighted stream nitrate and ammonium concentrations. At a subset of the catchments, we found that the length and period of analysis influenced whether trends were positive, negative or non-significant. Trends also differed among neighboring catchments within several Experimental Forests, suggesting the importance of catchment-specific factors in determining nutrient exports. Over the longest time periods, trends were more consistent among catchments within sites, although there are fewer long-term records for analysis. These findings highlight the critical value of long-term, uninterrupted stream chemistry monitoring at a network of sites across the USA to elucidate patterns of change in nutrient concentrations at minimally disturbed forested sites.

Autry, A., and J. Fitzgerald. 1991. Short Communication: Determination of kinetic parameters for sulfur processing potentials: verification of the constant specific activity approach. Soil Biology and Biochemistry 23(10): 1003-1004.

Abstract
A modification of the heterotrophic activity method of Wright and Hobbie (1966) was used to determine kinetic parameters for organic S formation and sulfate adsorption by forest soil. Kinetic parameters for sulfate adsorption, including saturation potentials and the concentration of added sulfate yielding saturation, can be determined by visual inspection of the saturation curves. Samples were collected from the A, B, BC, and C horizons of an eastern white pine forest (Watershed 1) located at the Coweeta Hydrologic Laboratory.

Autry, A.R., and J.W. Fitzgerald, and P.R. Caldwell. 1990. Sulfur fractions and retention mechanisms in forest soils. Canadian Journal of Forest Research 20: 337-342.

Abstract
Organic S was found to constitute over 78% of total S in the uppermost mineral(0-20 cm; A,E) horizons. Several forests of varying elevation, vegetation, location, and soil type were considered. Organic S exceeded 65% of total S inall but one site for both intermediate (20-40 cm; primarily A/B) and deeper (40+cm; B,C) horizons. In almost all cases, the adsorbed sulfate anion constituted substantially less of the total S than did organic S. Carbon-bonded S was themost prevalent form of organic S for most sites at all depths. Adsorbed estersulfate, recovered by extraction with basic phosphate, generally constituted a substantial portion of the adsorbed S pool for both O1 and O2 components of the forest floor and for the uppermost mineral horizon of most sites. This trend did not hold true with increasing depth. Because organic S was the dominant form of S, irrespective of horizon, the data suggest that organosulfur formation, not sulfate adsorption, may represent the primary mechanism for S retention in forest soil.

Autry, A.R., and J.W. Fitzgerald. 1990. Sulfonate-S a major form of forest soil organic sulfur. Biology and Fertility of Soil 10: 50-56.

Abstract
Several forests of varying elevations, soils, and vegetation were studied to evaluate the relative importance of sulfonate S, amino S, and ester sulfate as constituents of soil organic S. Sulfonate S exceeded 40% of total S in O1 horizon of all but one site examined, and comprised at least 50% of total S in the O2 horizons of 14 out 18 study sites. Sulfonate pool sizes, on a percentage basis, tended to decrease with increasing sample depth within the mineral horizons, but sulfonate S was still a major form of organic S in the C horizon. Amino-acid S pool sizes were lower than those for sulfonate and decreased with increasing depth at all but one site. Ester sulfate pool sizes were generally less than those of sulfonate S and greater than those of amino-acid S in the O1, O2, and A horizons. In the intermediate and lowest soil horizons, ester sulfate levels exceeded those for sulfonate S in half the sites. Thus, sulfonate S is a major form of organic S in forest soils, irrespective of depth.

Autry, A.R., and J.W. Fitzgerald. 1991. Organosulfur formation in forest soils: site comparison of kinetic parameters. Soil Biology and Biochemistry 23(7): 689-693.

Abstract
Soil samples were collected at various depths in forested sites that should have different sulfate deposition histories. Saturation potentials, based on the Vmax for SO4-S incorporation into organic matter, were found to decrease with increasing depth in 8 out of 12 sites. Estimation of the SO4-S concentration required to saturate a given horizon was made and, irrespective of depth, a forest located near a coal-fired power plant was the most saturated whereas samples from forests located in relatively non-polluted areas were generally the least saturated. This latter parameter was found to decrease with increasing depth in 6 out of 12 sites. Turnover times for the recently-formed organic S exceeded 103 h in approximately half of the sites at all soil horizons. These results indicate that no significant change in the recalcitrance of the newly-formed organic S occurred with increasing depth.

Autry, A.R., and J.W. Fitzgerald. 1991. Potential for organic sufur accumulation in a variety of forest soils at saturating concentrations of sulfate. Biology Fertility of Soils 10: 281- 284.

Abstract
Increasing the sulfate concentration and concomitant increases in the organic S concentration failed to exert any effect on organic S mobilization in samples collected from all depths within the mineral soil profile, from 15 sites differing in soil type, vegetation, and geographic location. Mobilization capacities at saturating concentrations of sulfate for organic S formation generally tended to increase with increasing depth. The potentials for the accumulation of organic S with various sulfate inputs exhibited saturation kinetics similar to those observed for organic S formation; values for the former parameter ranged from 3x10-3 to 12.6 +mol S g-1 dry weight 24 h-1 for the uppermost (A, E) soil horizons, 3 nmol to 10+mol S g-1 dry weight 24 h-1 for intermediate (primarily AB) soil horizons, and from 3 nmol to 13.4+mol S g-1 dry weight 24 h-1 intermediate (primarily AB) soil horizons, for the lowermost (B,C) soil horizons. Irrespective of depth, the Fullerton, Tarklin, and Loblolly sites in Tennessee and the Florida site showed the least net accumulation of organic S at saturation (<0.2 +mol S g-1 dry weight 24 h-1 for all horizons examined), while the Duke Forest (North Carolina), Douglas Fir (Washington), Whiteface (New York) and the Howland (Maine) sites had the highest potential net accumulation of organic S at saturation (>1.0 +mol S g-1 dry weight 24 h-1 for most horizons examined).

Autry, A.R., and J.W. Fitzgerald. 1993. Relationship between microbial activity, biomass and organosulfur formation in forest soil. Soil Biology and Biochemistry 25(1): 33-39.

Abstract
The capacity to form organic S was detained for microorganisms present in soil samples collected from different depths of an eastern white pine forest. Inhibitors of eukaryotes (cycloheximide and amphotericin B), gram-negative prokaryotes (polmyxin B), and aerobically-respiring prokaryotes and eukaryotes (sodium azide) were used to assess the relative contribution of each group to organosulfur formation over a wide range of added sulfate. Values for microbial biomass (direct counts and ATP content) and activity (soil respiration) were estimated and correlated with organosufur formation potentials at various soil depths. Most of this latter activity, regardless of concentration of added sulfate, was mediated by aerobically respiring prokaryotes. In each horizon, however, increasing concentrations of sulfate induced a shift in the physiological types of microbial populations responsible for organic S samples collected from each horizon. ATP pool sizes and native soil respiration rates exhibited positive saturating concentration of sulfate (r=0.79, 0.72, respectively) were employed, separately. amounts of added sulfate also had a positive effect on soil respiration rates (P<001). Collectively, the data suggest that exposure to sulfate stimulated endogenous aerobic respiration, generating ATP, that was used in part to form organic S.

Baas, Peter & Knoepp, J & Markewitz, Daniel & Mohan, Jacqueline. (2017). Areas of residential development in the southern Appalachian Mountains are characterized by low riparian zone nitrogen cycling and no increase in soil greenhouse gas emissions. Biogeochemistry. DOI:10.1007/s10533-017-0318-9.

Abstract
The critical role streamside riparian zones play in mitigating the movement of nitrogen (N) and other elements from terrestrial to aquatic ecosystems could be threatened by residential development in the southern Appalachian Mountains. Many studies have investigated the influence of agriculture on N loading to streams but less is known about the impacts of residential development. Here we consider the dynamics of changing riparian land use in the southern Appalachians that includes increased residential development at the expense of both forests and agriculture. We hypothesized that increased inputs of inorganic N from residential development will increase nitrogen cycling rates relative to forests, thereby preventing terrestrial N retention and increasing soil nitrate losses through leaching. In addition, we hypothesized that such development will increase emissions of N2O, CO2, and CH4, all potent greenhouse gases. We found riparian soil potential N cycling rates as well as N2O and CO2 efflux to be much greater with agricultural land use compared to either forested or residential land use. Our data suggest that residential development of forested riparian ecosystems does not increase N cycling or removal and, thus, might allow for greater potential N leaching into streams. Both agricultural and residential land use exhibited CH4 efflux while forested ecosystems were responsible for CH4 uptake. Overall, regional greenhouse gas emissions are projected to decline as high N2O and CO2 emitting agricultural land is converted to residential use.

Baer, S., Siler, E., Eggert, S., Wallace, J. 2001. Colonization and production of macroinvertebrates on artificial substrata: upstream-downstream responses to a leaf litter exclusion manipulation. Freshwater Biology, 46: 347-365

Abstract
1. Macroinvertebrate colonization dynamics were examined on artificial substrata in a stream with terrestrial litter inputs excluded, downstream of the litter exclusion treatment, and in a reference stream. 2. Short-term examination of the rates of organic matter accrual and invertebrate colonization demonstrated significantly lower accumulation of leaf detritus and invertebrates in the litter-excluded reach and a short distance downstream of that reach. 3. All major fractions of organic matter and invertebrates declined on artificial substrata during the 3-year litter exclusion. Further, secondary production on artificial substrata in the litter-excluded reach decreased from 6.2 to 1.5 g AFDM m-1 year -1 from pretreatment to the third year of litter exclusion, respectively. 4. Downstream, fine particulate matter on artificial substrata decreased during litter exclusion, and there was a significant reduction in colonization of collector-filterers. Total secondary production downstream of the litter exclusion declined >70%, demonstrating that downstream colonization dynamics are linked to upstream detritus inputs and processing by stream invertebrates.

Baer, S.G., E.R. Siler, S.L. Eggert, and J.B. Wallace. 2001. Colonization and production of macroinvertebrates on artificial substrata: upstream-downstream responses to a leaf litter exclusion manipulation. Freshwater Biology. 46: 347-365.

Abstract
Macroinvertebrate colonization dynamics were examined on artificial substrata in a stream with terrestrial litter inputs excluded, downstream of the litter-exclusion treatment, and in a reference stream. Short-term examination of the rates of organic matter accrual and invertebrate colonization demonstrated significantly lower accumulation of leaf detritus and invertebrates in the litter-excluded reach and a short distance downstream of that reach. All major fractions of organic matter and invertebrates declined on artificial substrata during the 3-year litter exclusion. Further, secondary production on artificial substrata in the litter-excluded reach decreased from 6.2 to 1.5 g AFDM m-2 year-1 from pretreatment to the third year of litter exclusion, respectively. Downstream, fine particulate organic matter on artificial substrata decreased during litter exclusion, and there was a significant reduction in colonization of collector-filterers. Total secondary production downstream of the litter exclusion declined >70%, demonstrating that downstream colonization dynamics are linked to upstream detritus inputs and processing by stream invertebrates.

Bain, D. J, Green, M. B, Campbell, J. L, Chamblee, J.F., Chaoka, S., Fraterrigo, J.M., Kaushal, S. S, Martin, S. L, Jordan, T. E, Parolari, A. J, Sobczak, W. V, Weller, D. E, Wolheim, W. W, Boose, E. R, Duncan, J., Gettel, G. M, Hall, B. R, Kumar, P., Thompson, J. R, Vose, J.M., Elliott, E. M and Leigh, D.S. 2012. Legacy Effects in Material Flux: Structural Catchment Changes Predate Long-Term Studies. Bioscience. 62(6):575-584.

Abstract
Legacy effects of past land use and disturbance are increasingly recognized, yet consistent definitions of and criteria for defining them do not exist. To address this gap in biological- and ecosystem-assessment frameworks, we propose a general metric for evaluating potential legacy effects, which are computed by normalizing altered system function persistence with duration of disturbance. We also propose two distinct legacy-effect categories: signal effects from lags in transport and structural effects from physical landscape changes. Using flux records for water, sediment, nitrogen, and carbon from long-term study sites in the eastern United States from 1500 to 2000, we identify gaps in our understanding of legacy effects and reveal that changes in basin sediment dynamics precede instrumented records. These sediment dynamics are not generally incorporated into interpretations of contemporary records, although their potential legacy effects are substantial. The identification of legacy effects may prove to be a fundamental component of landscape management and effective conservation and restoration practice.

Baker, T.T. and D.H. Van Lear. 1998. Relations between density of rhododendron thickets and diversity of riparian forests. Forest Ecology and Management. 109: 21-32.

Abstract
Rosebay rhododendron (Rhododendron maximum L.) is increasing its range and abundance in understories of southern Appalachian forests, reducing species richness, and altering patterns of succession. This study characterized the density and biomass attributes of R. maximum thickets and examined their effects on plant species richness, percent cover, and regeneration patterns within a southern Appalachian riparian ecosystem.

Ball, B. A., M. D. Hunter, J. S. Kominoski, C. M. Swan, and M. A. Bradford. 2008. Consequences of non-random species loss on decomposition dynamics: Evidence for additive and non-additive effects. Journal of Ecology 96:303-313.

Abstract
To examine potential impacts of non-random species loss on ecosystems, we studied additive and non-additive effects of litter mixing on decomposition. A full-factorial litterbag experiment was conducted using four deciduous leaf species, from which mass loss and nitrogen content were measured. Data were analysed using a statistical approach that first looks for additive identity effects based on the presence or absence of species and then significant species interactions occurring beyond those. It partitions non-additive effects into those caused by richness and/or composition.

Ball, B.A., Bradford, M.A. 2009. Nitrogen and Phosphorus Release from Mixed Litter Layers is Lower than Predicted from Single Species Decay. Ecosystems 12: 87-100

Abstract
Ecosystem-level nutrient dynamics during decomposition are often estimated from litter monocultures. If species effects are additive, we can statistically predict nutrient dynamics in multispecies systems from monoculture work, and potential consequences of species loss. However, if species effects are dependent on interactions with other litter species (that is, non-additive), predictions based on monoculture data will likely be inaccurate. We conducted a 3-year, full-factorial, mixed-litter decomposition study of four dominant tree species in a temperate forest and measured nitrogen and phosphorus dynamics to explore whether nutrient dynamics in mixtures were additive or non-additive. Following common approaches, we used litterfall data to predict nutrient dynamics at the ecosystem-level. In mixtures, we observed non-additive effects of litter mixing on nutrient dynamics: the presence of nutrient-rich species in mixture facilitated nutrient release, whereas nutrient-poor species facilitated nutrient retention. Fewer nutrients were released from mixtures containing high-quality litter, and more immobilized from mixtures containing low-quality litter, than predicted from monocultures, creating a difference in overall nutrient release between predicted and actual dynamics in litter mixtures. Nutrient release at the ecosystem-level was greatly overestimated when based on monocultures because the effect of species interactions on nutrient immobilization was not accounted for. Our data illustrate that the identity of species in mixtures is key to their role in non-additive interactions, with repercussions for mineral nutrient availability and storage. These results suggest that predictions of ecosystem-level nutrient dynamics using litter monoculture data likely do not accurately represent actual dynamics because the effects of litter species interactions are not incorporated.

Ball, B.A., Bradford, M.A., Coleman, D.C., Hunter, M.D. 2009. Linkages between below and aboveground communities: Decomposer responses to simulated tree species loss are largely additive. Soil Biology and Biochemistry. 40: 155-1163.

Abstract
Inputs of aboveground plant litter influence the abundance and activities of belowground decomposer biota. Litter-mixing studies have examined whether the diversity and heterogeneity of litter inputs affect decomposer communities inways that can be predicted from monocultures. They have mainly attempted to detect non-additive effects of litter mixing, although individual species effects (additivity) as well as species interactions (non-additivity) may alter decomposition rates. To determine potential impacts of plant species loss on aboveground-decomposer linkages, we assessed both additive and non-additive effects of litter mixing on decomposer communities. A full-factorial litterbag experiment with leaves from four deciduous tree species was conducted, to assess responses of bacteria, fungi, nematodes, and microarthropods. Data were analyzed using a statistical method that first looked for additive effects based on the presence or absence of species and then any significant species interactions. We observed almost exclusively additive effects of all four litter species on decomposer biota, with each species exerting effects on different aspects of the community. These results imply that the consequences of species loss for the decomposer community will be largely predictable from knowledge of single species litter dynamics. The two species at opposite ends of the quality spectrum exerted the most effects. Highquality Liriodendron tulipifera supported a more diverse arthropod community and drove bottom-up effects on the decomposer food web. Low-quality Rhododendron maximum had negative effects on most groups of biota. Litter of mid-quality species exerted fewer effects. The influence of litter species richness on the Tylenchidae (nematodes) was the only non-additive effect of litter mixing. Together, these data demonstrate an effect of plant community composition on decomposer biomass, abundance, and diversity, confirming a link between above and belowground communities. We were able to identify the species to which the decomposer community is most sensitive, aiding predictions of the consequences of the loss of these dominant species on the decomposer community, with potential feedbacks for organic matter and nutrient turnover.

Band, L. E., McDonnell, J. J., Duncan, J. M., Barros, A., Bejan, A., Burt, T., Dietrich, W. E., Emanuel, R. E., Hwang, T., Katul, G., Kim, Y., McGlynn, B., Miles, B., Porporato, A., Scaife, C. and Troch, P. A. (2014), Ecohydrological flow networks in the subsurface. Ecohydrol., 7: 1073–1078. doi:10.1002/eco.1525

Abstract
Preferential flow in hillslope systems through subsurface networks developed from a range of botanical, faunal and geophysical processes have been observed and inferred for decades and may provide a large component of the bulk transport of water and solutes. However, our dominant paradigm for understanding and modelling hillslope hydrologic processes is still based on the Darcy–Richards matric flow framework, now with a set of additional methods to attempt to reproduce some of the aggregate function of the two-phase system of network and matrix flow. We call for a community effort to design and implement a set of well planned experiments in different natural and constructed hillslopes, coupled with the development of new theory and methods to explicitly incorporate and couple the co-evolution of subsurface flow networks as intrinsic components of hydrological, ecological and geomorphic systems. This is a major community challenge that can now benefit from new experimental infrastructure, renewal of older infrastructure and recent advances in sensor systems and computational capacity but will also require a sustained and organized interdisciplinary approach.

Band, L.E., Hwang, T., Hales, T., Vose, J.M. and Miniat, C.F. 2012. Ecosystem processes at the watershed scale: Mapping and modeling ecohydrological controls of landslides. Geomorphology. 137(1):159-167.

Abstract
Mountain watersheds are sources of a set of valuable ecosystem services as well as potential hazards. The former include high quality freshwater, carbon sequestration, nutrient retention, and biodiversity, whereas the latter include flash floods, landslides and forest fires. Each of these ecosystem services and hazards represents different elements of the integrated and co-evolved ecological, hydrological and geomorphic subsystems of the watershed and should be approached analytically as a coupled land system. Forest structure and species are important influences on the partitioning of precipitation, the lateral redistribution of water, runoff and sediment production, weathering and soil development. Forest regulation of hydrologic dynamics contributes to the development of patterns of soil pore pressure and slope instability during storms or snowmelt. The spatial patterns of root depth, structure and strength, developed by the below ground allocation of carbon in the forest canopy in response to limiting resources of water and nutrients, contributes to slope stability and drainage, and the maintenance of stomatal conductance linking water and carbon cycling. This in turn provides the photosynthate required to build leaf area, stem and root biomass. The linked ecological, hydrologic and geomorphic systems are characterized by specific catenary patterns that should be captured in any coupled modeling approach. In this paper we extend an ecohydrological modeling approach to include hydrologic and canopy structural pattern impacts on slope stability, with explicit feedbacks between ecosystem water, carbon and nutrient cycling, and the transient development of landslide potential in steep forested catchments. Using measured distributions of canopy leaf area index, and empirically modeled soil depth and root cohesion, the integrated model is able to generate localized areas of past instability without specific calibration or training with mapped landslides. As the model has previously been shown to simulate space/time patterns of coupled water, carbon and nutrient cycling, the integration of slope stability as a function of hydrologic, ecosystem and geomorphic processes provides the ability to closely link multiple ecosystem services with a unified approach.

Bardgett, R., Anderson, J., Behan-Pelletier, V. et al. Ecosystems (2001) 4: 421. https://doi.org/10.1007/s10021-001-0020-5

Abstract
The boundaries between terrestrial and aquatic ecosystems, known as critical transition zones (CTZ), are dynamic interfaces for fluxes of water, sediment, solutes, and gases. Moreover, they often support unique or diverse biotas. Soils, especially those of riparian zones, have not been recognized as CTZ even though they play a critical role in regulating the hydrologic pathways of infiltration and leaching, or runoff and erosion, which can cumulatively affect biogeochemical processes and human livelihoods at landscape scales. In this review, we show how the processes that regulate hydrologic fluxes across and through soil CTZ are influenced by the activities of soil biota. Our message is fourfold. First, there are a variety of ways in which soil biodiversity, in terms of richness and dominance, can influence hydrological pathways in soil and thus the transfer of materials from terrestrial to aquatic ecosystems. Second, the influence of soil organisms on these hydrological pathways is very much interlinked with other environmental, soil biophysical, and vegetation factors that operate at different spatial and temporal scales. Third, we propose that the influence of soil biodiversity on hydrological pathways is most apparent (or identifiable), relative to other factors, in situations that lead to the dominance of certain organisms, such as larger fauna. Fourth, soils are buffered against environmental change by biophysical properties that have developed over long periods of time. Therefore, the effects of changes in soil biodiversity on hydrological processes at the ecosystem scale might be delayed and become most apparent in the long term.

Barr, T.C. Jr. 1971. The North American Pterostichus of the subgenus Cylindrocharis Casey (Coleoptera, Carabidae). Novitates 2445. American Museum of Natural History, New York, NY.

Abstract
Cylindrocharis Casey, a subgenus of Pterostichus Bonelli, includes three species: P. (C.) rostratus (Newman), ranging from southeastern Canada to the southern Appalachian Mountains of Tennessee and North Carolina; P. (C.) acutipes, new species, from central Kentucky and Tennessee to the mountains of Tennessee, North Carolina, and northeast Georgia; and P. hypogeus, new species, from the Nantahala and Snowbird Mountains, North Carolina. The central Kentucky populations of acutipes are described as a distinct subspecies, P. (C.) a. kentuckensis.

Barrett, J.C., and G.D. Grossman. 1988. Effects of direct current electrofishing on the mottled sculpin. North American Journal of Fisheries Management 8: 112-116.

Abstract
The effects of electrofishing on the survival of mottled sculpin Cottus bairdi were examined. Three tanks each were filled with mottled sculpin collected by electrofishing (treatment) and kick-seining (control), were maintained for at least 30 d and all deaths recorded. Patterns of survival were not significantly different among tanks between all control tanks versus all treatment tanks. Failure to demonstrate a treatment effect in either experiment suggests that electrofishing does not adversely affect the short-term survival of mottled sculpin; a similar result was obtained for several other stream fishes. To test the effects of multiple electrofishing exposures, we conducted another experiment in four artificial stream sections. Treatment mottled sculpin were shocked, and both treatment and control fish were handled, weekly, for 5 weeks. Although overall survival in all stream sections was lower than that seen in the first experiment, there were no significant differences in survival among sections or between treatments in this experiment. These data suggest that handling stress was a greater determinant of mortality rates than was electrofishing.

Barten, P.K. 1989. Forest hydrology and ecology at Coweeta. American Scientist 78: 64.

Abstract
A review of the Coweeta Symposium volume.

Bartman, C.E., K.C. Parker, J. Laerm, and T.S. McCay. 2001. Short-Term Response Of Jordan's Salamander To A Shelterwood Timber Harvest In Western North Carolina. Physcial Georgraphy. 22(2): 154-166.

Abstract
The effects of shelterwood cutting on the abundance of Jordan+s salamander (Plethodon jordani) in western North Carolina were examined during 1997 and 1998. Terrestrial salamander assemblages were sampled before, immediately after, and one year after timber harvest on control and treatment plots to estimate abundance. We also surveyed salamanders immediately after the harvest along transects radiating out from cut plots to determine whether cutting triggered salamander emigration from disturbed plots. Both before and after timber harvest, the site was strongly dominated by Jordan+s salamander. No significant effects of initial shelterwood cutting on Jordan+s salamander abundance were apparent after timber harvest. Abundance of this species decreased from precutting to post-cutting sampling on both control and treatment plots, which likely relected the drought that characterized both post-cutting sampling periods, but not pre-cutting sampling. No emigration of salamanders from the cut plots was detected after timber harvest. These findings suggest that at a stand scale, shelterwood harvests may pose less of a short-term threat to salamander populations than clearcutting, but more study is necessary to assess broad-scale tradeoffs between harvest yield and biological impacts associated with alternative timber harvest methods.

Barton, C.D., Andrews, D.M., Kolka, R.A. 2008. Evaluating Hydroperiod Response in Restored Carolina Bay Wetlands Using Soil Physicochemical Properties. Restoration Ecology 16(4) 668-677.

Abstract
Carolina bays are shallow depression wetlands found in the southeastern United States that have been severely altered by human activity. The need to restore these complex and diverse systems is well established, but our limited understanding of wetland hydrologic processes in these systems hinders our ability to assess the effectiveness of bay restoration efforts. Carolina bays exhibit a wide range of moisture regimes from seasonally saturated to semipermanently inundated. Differing physicochemical properties of soils within bay interiors may control bay hydrology. However, previous efforts to establish relationships between soil characteristics and bay hydrology have been inconclusive. An assessment of soil and hydroperiod was initiated in 16 bays designated to be restored and 6 bays that were not restored (reference). Soil morphology was described, and permanent monitoring wells were installed at each site. Multiple regression analysis was used to determine relationships between the soil physicochemical characteristics and the bay hydroperiod for restored and reference bays in both pre- and postrestoration periods. A significant relationship (r2 = 0.75, p = 0.02) between prerestoration hydroperiod and clay content in the argillic horizon (Bt) of the reference bays was observed. This relationship was then used to evaluate hydroperiod change in the restored bays from the postrestoration period. The relationship accurately identified sites that exhibited high prerestoration hydroperiods and did not need hydrologic restoration (n = 4) and effectively showed sites that exhibited substantial increases in hydroperiod due to the restoration activities (n = 7).

Beachy, C., Bruce, R. 2003. Life history of a small form of the plethodontid salamander Desmognathus quadramaculatus. Amphibia-Reptilia, 24 (1): 13-26

Abstract
We sampled Desmognathus quadramaculatus, one of the largest species of plethodontid salamanders in eastern North America, from a population exhibiting extremely small adult body sizes in the Bald Mountains of North Carolina (USA). In order to test the hypothesis that miniaturization in desmognathine salamanders is due to early metamorphosis and maturation, we estimated ages and sizes at metamorphosis and maturation. Analysis of size-frequency distributions suggests that most larvae metamorphose after 24 months, with the remainder metamorphosing after 36. The minimum age of sexually mature individuals in the summer months is estimated to be 4 years in males and 5 years in females; some may mature 1 year earlier. This is earlier than other reliable estimates of age at maturation in D. quadramaculatus, and appears to account for the small size of the species at this locality. Larval and juvenile growth rates are within the range of growth rates of other populations. As in other populations of D. quadramaculatus, males are smaller than females at maturation, but grow to larger sizes. Estimates of clutch sizes based on dissection of gravid females are relatively low. The other species of salamanders in this community do not appear to be miniaturized.

Beckage, B., and J. Clark. 2005. Does predation contribute to tree diversity? Oecologia. 143: 458-469.

Abstract
Seed and seedling predation may differentially affect competitively superior tree species to increase the relative recruitment success of poor competitors and contribute to the coexistence of tree species. We examined the effect of seed and seedling predation on the seedling recruitment of three tree species, Acer rubrum (red maple), Liriodendron tulipifera (yellow poplar), and Quercus rubra (northern red oak), over three years by manipulating seed and seedling exposure to predators under contrasting microsite conditions of shrub cover, leaf litter, and overstory canopy. Species rankings of seedling emergence were constant across microsites, regardless of exposure to seed predators, but varied across years. A. rubrum had the highest emergence probabilities across microsites in 1997, but Q. rubra had the highest emergence probabilities in 1999. Predators decreased seedling survival uniformly across species, but did not affect relative growth rates (RGRs). Q. rubra had the highest seedling survivorship across microsites, while L. tulipifera had the highest RGRs. Our results suggest that annual variability in recruitment success contributes more to seedling diversity than differential predation across microsites. We synthesized our results from separate seedling emergence and survival experiments to project seedling bank composition. With equal fecundity assumed across species, Q. rubra dominated the seedling bank, capturing 90% of the regeneration sites on average, followed by A. rubrum (8% of sites) and L. tulipifera (2% of sites). When seed abundance was weighted by species-specific fecundity, seedling bank composition was more diverse; L. tulipifera captured 62% of the regeneration sites, followed by A. rubrum (21% of sites) and Q. rubra (17% of sites). Tradeoffs between seedling performance and fecundity may promote the diversity of seedling regeneration by increasing the probability of inferior competitors capturing regeneration sites.

Beckage, B., and J.S. Clark. 2003. Seedling survival and growth of three forest tree species: the role of spatial heterogeneity. Ecology: 84(7): 1849-1861.

Abstract
Spatial heterogeneity in microenvironments may provide unique regeneration niches for trees and may promote forest diversity. We examined how heterogeneity in understory cover, mineral nutrients, and moisture and their interactions with canopy gaps contribute to the coexistence of three common, co-occurring tree species. We measured survival and height growth of 1080 seedlings of Acer rubrum (red maple), Liriodendron tulipifera (yellow poplar), and Quercus rubra (red oak) that were planted in one of five understory treatments: removal of understory vegetation, trenched, trenched plus removal of understory vegetation, fertilization, and a control. Understory treatments were replicated in 12 paired gap and canopy environments. Survivorship varied among species, with Q. rubra having the highest probability of surviving beyond the 1135-day experiment (probability = 0.64), followed by A. rubrum (probability = 0.27) and L. tulipifera (probability = 0.07). Although canopy gaps and understory treatments had large effects on survivorship, species survival rankings changed little across microenvironments; Q. rubra had the highest survival in all microenvironments. In contrast to survival, L. tulipifera had a relative growth rate for height that was three times greater than that of A. rubrum and Q. rubra in high-resource microenvironments. There was broad overlap among species in relative growth rates in the remaining seven microenvironments, with no clear top-ranked species. Differences in seedling growth and survival across these 10 microenvironments may contribute to the coexistence of two of the three species studied, L. tulipifera and Q. rubra, but not A. rubrum. Q. rubra had higher survival than A. rubrum and L. tulipifera in all microenvironments, but L. tulipifera tended to grow faster than A. rubrum and Q. rubra in high-resource microenvironments. Despite the generally poor performance of A. rubrum, it was the only surviving species in some quadrats at the end of the experiment, indicating that stochastic effects, in conjunction with broad niche overlap, may also contribute to species coexistence. The importance of stochastic effects will probably increase when differential fecundity across these three species is considered because the high fecundity of A. rubrum offsets survival and growth disadvantages of its seedlings through their greater total abundance.

Beckage, B., B.D. Kloeppel, J.A. Yeakley, S.F. Taylor, and D.C. Coleman. 2008. Differential effects of understory and overstory gaps on tree regeneration. Journal of the Torrey Botanical Society. 135(1):1-11.

Abstract
Gaps in the forest canopy can increase the diversity of tree regeneration. Understory shrubs also compete with tree seedlings for limited resources and may depress tree recruitment. We compared effects of shrub removal and canopy windthrow gaps on seedling recruitment and understory resource levels.

Beckage, B., J.S. Clark, B.D. Clinton, and B.L. Haines. 2000. A long-term study of tree seedling recruitment in southern Appalachian forests: the effects of canopy gaps and shrub understudies. Canadian Journal Forestry Research. 30: 1617-1631.

Abstract
We examined the importance of intermediate-sized gaps and a dense shrub layer on tree seedling recruitment in a southern Appalachian deciduous forest. We created 12 canopy gaps under two contrasting understory conditions: 6 gaps were dominated by the dense, shade-producing shrub, Rhododendron maximum L., while the remaining gaps were relatively open. Density of first-year and >first-year seedlings was monitored for 5 years in transects extending from adjacent undisturbed forest through the experimental gaps. We concurrently measured the understory light environment, soil moisture, litter biomass, and seed rain. Neither species diversity nor richness consistently increased following gap formation. Acer rubrum L. responded consistently to canopy gaps with increased seedling densities while most other species, including both shade-tolerant and shade-intolerant species, did not. Seedling densities were especially low and unresponsive to gap formation in areas dominated by R. maximum. Understory light levels were consistently low beneath R. maximum and did not increase with canopy gap formation. Our results suggest that dense shrub cover can neutralize recruitment opportunities in canopy gaps, that seed rain often limits recruitment in gaps, and that canopy gaps that are larger or include understory disturbance are needed to maintain diversity in these forests.

Beckage, B., L. Joseph, P. Belisle, D.B. Wolfson, and W.J. Platt. 2007. Bayesian change-point analyses in ecology. New Phytologist. 174: 456-467.

Abstract
Ecological and biological processes can change from one state to another once a threshold has been crossed in space or time. Threshold responses to incremental changes in underlying variables can characterize diverse processes from climate change to the desertification of arid lands from overgrazing. Simultaneously estimating the location of thresholds and associated ecological parameters can be difficult: ecological data are often ‘noisy’, which can make the identification of the locations of ecological thresholds challenging. We illustrate this problem using two ecological examples and apply a class of statistical models well-suited to addressing this problem. We first consider the case of estimating allometric relationships between tree diameter and height when the trees have distinctly different growth modes across life-history stages. We next estimate the effects of canopy gaps and dense understory vegetation on tree recruitment in transects that transverse both canopy and gap conditions. The Bayesian change-point models that we present estimate both threshold locations and the slope or level of ecological quantities of interest, while incorporating uncertainty in the change-point location into these estimates. This class of models is suitable for problems with multiple thresholds and can account for spatial or temporal autocorrelation.

Beckage, B., M. Lavine, and J. Clark. 2005. Survival of tree seedlings across space and time: estimates from long-term count data. Journal of Ecology. 93: 1177-1184.

Abstract
(1) Tree diversity in forests may be maintained by variability in seedling recruitment. Although forest ecologists have emphasized the importance of canopy gaps in generating spatial variability that might promote tree regeneration, the effects of canopy gaps on seedling recruitment may be offset by dense forest understories. (2) Large annual fluctuations in recruitment processes, coupled with the long life of forest trees, can provide an alternative mechanism for maintaining tree diversity. Evaluating the relative importance of spatial vs. temporal variability in recruitment, however, requires estimates of seedling survival that are extensive on both scales. (3) Estimates of survival derived from conventional statistical methods require that individual seedlings are monitored through time, and are therefore often limited in extent. (4) We demonstrate a relatively fast and easy alternative approach to measuring survival that uses repeated counts of individuals in quadrats. (5) Annual seedling counts were used to quantify both the effects of small canopy gaps and understorey shrubs on the survival of Acer rubrum (red maple) seedlings and the magnitude of residual spatial and temporal variability in seedling survival. (6) We found that a dense understorey had a greater effect on seedling survival than did canopy gaps. Our canopy gaps had only a slight positive effect on seedling survival, and their benefit was offset by a large negative effect of the understorey shrub Rhododendron maximum. (7) Annual fluctuations in recruitment processes were seven times greater than spatial variability across transects and the effect of individual years on seedling survival was larger than even that of understorey shrubs. (8) The long life span of trees coupled with large annual variability in recruitment success across species may maintain the diversity of forest trees through a storage effect.

Becker, V.E. 1980. Nitrogen Fixing Lichens in Forests of the Southern Appalachian Mountains of North Carolina. The Bryologist 83(1) 29-39.

Abstract
The abundance and species diversity of nitrogen fixing lichens were determined for several forests of the southern Appalachian Mountains of western North Carolina. Gray beech forests of wet, high-elevation beech gaps were aus- picious locations for these lichens. The bark of Aesculus octandra Marshal was the optimum habitat, particularly for the dominants Lobaria quercizans Michx. and Lobaria pulmonaria (L.) Hoffm. Lichen biomass in this gray beech forest commonly ranged from 7 to 9 kg ha-' but was higher where Aesculus octandra was abundant. Lichens were less abundant in oak forests and cove forests, and none was found on conifers. The annual contribution of ammonia nitrogen by lichens was roughly estimated to be 0.8 kg ha-' for the gray beech forest in beech gaps.

Beier, C.M., J.L. Horton, J.F. Walker,B.D. Clinton, and E.T. Nilsen. 2005. Carbon limitation leads to suppression of first year oak seedlings beneath evergreen understory shrubs in Southern Appalachian hardwood forests. Plant Ecology. 176: 131-142.

Abstract
Inhibition of canopy tree recruitment beneath thickets of the evergreen shrubs Rhododendron maximum L. and Kalmia latifolia L. has long been observed in Southern Appalachian forests, yet the mechanisms of this process remain unresolved. We present a first-year account of suppression of oak seedlings in relation to Rhododendron and Kalmia basal area, light and resource availability, seedling performance and the rates of seedling damage (i.e., herbivory). We found no evidence of first-year seedling suppression or significant resource deficiencies beneath thickets of K. latifolia in mature mixed hardwood stands. Suppression beneath R. maximum was apparent during the first growing season. We found that seedling biomass, light availability prior to canopy closure, and seedling tissue C:N ratios were negatively correlated with R. maximum basal area. Basal area of R. maximum was positively correlated with seedling mortality rates, soil [Al], and early-growing season leaf herbivory rates. Seedling growth was positively correlated with light and tissue C:N, while negatively correlated with soil [Al]. Overall, our results support the inhibition model of shade-mediated carbon limitation beneath dense understory shrubs and indicate the potential importance of herbivory and aluminum toxicity as components of a suppression mechanism beneath R. maximum thickets. We present a causal model of first year inhibition beneath R. maximum in the context of our findings and the results of prior studies. Rosenfeld, Brian Jay. 2003. Developing a new fuel load mapping strategy using: digital photogrammetry; international classification of ecological communities; USDA Forest Service, forest inventory and analysis protocols; and disturbance history. Price, Myra Ann. 1998. Seasonal variation in runoff curve number. Tuscon, AZ: Univeristy of Arizona. 189 p. M.S. thesis. Hawkins, Richard H. 1993. Asymptotic determination of runoff curve numbers from data. Journal of Irrigation and Drainage Engineering. 119(2): 334-345. Background, general instructions, and examples are given fodirect runoff data sets. The technique matches rank-ordered (i.e., sorted) rainfall and runoffs, which preserves the return-period matching between the rainfalls and the runoffs. Usually a secondary trend

Belden, Lisa K., William E. Peterman, Stephen A. Smith, Lauren R. Brooks, E.F. Benfield, Wesley P. Black, Zhaomin Yang and Jeremy M. Wojdak. 2012. Metagonimoides oregonensis (Heterophyidae: Digenea) Infection In Pleurocerid Snails and Desmognathus quadramaculatus Salamander Larvae In Southern Appalachian Streams. Journal of Parasitology 98(4):760-767.

Abstract
Metagonimoides oregonensis (Heterophyidae) is a little-known digenetic trematode that uses raccoons and possibly mink as definitive hosts, and stream snails and amphibians as intermediate hosts. Some variation in the life cycle and adult morphology in western and eastern populations has been previously noted. In the southern Appalachians, Pleurocera snails and stream salamanders, e.g., Desmognathus spp., are used as intermediate hosts in the life cycle. We completed a series of studies in this system examining some aspects of larval trematode morphology and first and second intermediate host use. Molecular sequencing of the 28S rDNA of cercariae in our survey placed them clearly within the heterophyid family. However, light and scanning electron microscopy revealed both lateral and dorso-ventral finfolds on the cercariae in our region, whereas original descriptions of M. oregonensis cercariae from the west coast indicate only a dorso-ventral finfold, so further work on the systematics of this group may be warranted. A survey of first intermediate host, Pleurocera proxima, from 7 streams in the region identified only M. oregonensis, virgulate-type cercariae, and cotylomicrocercous-type cercariae in the streams, with M. oregonensis having the highest prevalence, and the only type present that use amphibians as second intermediate hosts. Based on clearing and staining of 6 Desmognathus quadramaculatus salamander larvae, we found that individual salamanders could have over 600 metacercariae, which form between muscle fibers throughout the body. Histological observations suggest that the metacercariae do not cause excessive tissue damage or inflammation, and likely persist through metamorphosis, thereby transmitting potentially large numbers of worms to definitive host raccoons foraging along streams.

Bell, D.M. & Clark, J.S. (2016), Seed predation and climate impacts on reproductive variation in temperate forests of the southeastern USA, Oecologia 180: 1223. doi:10.1007/s00442-015-3537-6

Abstract
Climatic effects on tree recruitment will be determined by the interactive effects of fecundity and seed predation. Evaluating how insect and vertebrate seed predators mediate tree reproductive responses to climate depends on long-term studies of seed production, development, and predation. In this study, our objectives were to (1) assess the effects of interannual climate variation on seed abortion rates, (2) assess the impact of seed density on predation rates, and (3) examine the degree to which density-dependent seed predation would amplify or dampen interannual variation in fecundity associated with seed abortion. We used a 19-year study of seed abortion and pre-dispersal predation rates by insects and vertebrates (birds and rodents) for five temperate tree species across forest plots from the North Carolina Piedmont to the Southern Appalachian Mountains in the southeastern USA. We found that rates of seed abortion and predation increased reproductive variation for oaks (Quercus species). Probability of seed abortion was greatest during years with cool, dry springs. Responses of seed predation on Quercus species to current year’s seed density varied by species, but exhibited positive density-dependence to previous year’s seed density consistent with numerical responses of seed predators. Seed abortion and predation rates for two drupe species responded little to variation in climate or seed density, respectively. Given that predation increased interannual variation in seed availability and the negative density-dependence to previous year’s seed density, our results indicate that consistent numerical responses of oak seed predators may amplify interannual variation due to climate-mediated processes like seed abortion.

Benfield, E.F. 1997. Comparison of litterfall input to streams. In Webster, J.R. and J.L. Meyer (eds.), Stream organic matter budgets. Journal of the North American Benthological Society. 16: 104-108.

Abstract
This chapter is part of a multi-site analysis of organic matter dynamics in streams. This chapter compares litterfall inputs to the streams. Climate (latitude) and vegetation type were more important than steam order in predicting litter inputs across a broad geographic range of streams, although within a river basin litterfall decreased with increasing stream order.

Benfield, E.F. and Jack R. Webster. 1985. Shredder abundance and leaf breakdown in an Appalachian Mountain stream. Freshwater Biology 15(1):113-120.

Abstract
1. Breakdown rates of dogwood (Cornus florida L.), red maple (Acer rubrum L.) and white oak (Quercus alba L.) leaves were investigated at two first-order and two second-order sites in an Appalachian Mountain stream. 2. Leaves exposed in mesh bags were sampled on eight occasions over a 207 day period and breakdown rates were compared using an exponential decay model. 3. There was a consistent ranking in leaf breakdown rate within each site, i.e. dogwood > red maple > white oak, and all species broke down faster at second- than at first-order sites. 4. Our data suggest that differences in species-specific leaf breakdown rates were largely a function of shredder abundance on the leaves.

Benfield, E.F., and J.R. Webster. 1991. Effects of forest disturbance on leaf breakdown in southern Appalachian streams. Verhandlungen Internationale Vereinlgung fur Theoretische und Angewandte Linmonogie 24: 1678-1690.

Abstract
Breakdown rates of four species of forest leaves were measured in streams at Coweeta draining logged and mature forested watersheds. Leaves were selected to range from those that breakdown rapidly (dogwood) to those that are resistant (rhododendron). Breakdown rates fit an exponential model of time and were generally faster in streams draining disturbed areas. Differences may be due to greater movement and abrasive action or to higher biological activity in the steams draining logged areas.

Benfield, E.F., J.R. Webster, J.J. Hutchens, J.L. Tank, and P.A. Turner. 2000. Organic matter dynamics along a streaorder and elevational gradient in a southern Appalachian stream. Verhandlungen International Vereinigung Limnologie. 27:1341-1345.

Abstract
Predictions of the River Continuum Concept include changes in physical factors such as geomorphology and temperature along a stream-order gradient (Vannote et al. 1980). Changes in macroinvertebrate diversity (Allan 1975), biomass (Grubaugh et al. 1996), and functional feeding group composition (Minshall et al. 1983) have been shown along such gradients. Changes in a variety of ecosystem processes along stream continua havealso been demonstrated (Minshall et al. 1983, Naiman et al. 1987). Huryn & Wallace (1987) and Grubaugh et al. (1996) found that macroinvertebrate habitat varies both longitudinally and locally and that sampling a single habitat (patch) may not be sufficient to reflect community composition throughout a stream continuum. Our objective was to investigate whether selected organic matter processes vary with patch type along a stream-order/elevational gradient.

Benfield, E.F., J.R. Webster, J.L. Tank, and J.J.Hutchens. 2001. Long-Term Patterns in Leaf Breakdown in Streams in Response to Watershed Logging. International Review of Hydrobiology. 86(4-5): 467-474.

Abstract
The watershed of Big Hurricane Branch, Coweeta Hydrologic Laboratory, North Carolina, USA, was logged in 1976. We measured breakdown rates of experimental leaf packs in this second-order stream prior to logging, during logging, soon after logging, and 3 additional times since then. Leaf breakdown was slow just after logging, apparently due to leaf burial by sediments. Thereafter, leaf breakdown rates have been consistently faster than before logging and faster than in a reference stream. These differences may be related to 3 factors. First, the post vlogging nitrate concentration has been about 3-10 times higher than pre-logging values in Big Hurricane Branch and 5 times higher than in reference stream. The high nutrient concentration may be stimulating microbial decomposition processes in leaf packs. Second, dominance of litterfall by (mediumá and (fastá processing leaves from the recovering forest coupled with relatively high sediment loads during storms may hasten breakdown through physical abrasion. Third, the interaction of high nutrients and high quality leaves may be attractive to leaf-shredding invertebrates whose feeding activities may also hasten the breakdown rates.

Benke, A., Huryn, A., Smock, L., Wallace, J. 1999. Length-mass relationships for freshwater macroinvertebrates in North America with particular reference to the southeastern United States. The North American Benthological Society, 18(3):308-343

Abstract
Estimation of invertebrate biomass is a critical step in addressing many ecological ques- tions in aquatic environments. Length-dry mass regressions are the most widely used approach for estimating benthic invertebrate biomass because they are faster and more precise than other methods. A compilation and analysis of length-mass regressions using the power model, M (mass) = a L (length)b, are presented from 30 y of data collected by the authors, primarily from the southeastern USA, along with published regressions from the rest of North America. A total of 442 new and published regressions are presented, mostly for genus or species, based on total body length or other linear measurements. The regressions include 64 families of aquatic insects and 12 families of other invertebrate groups (mostly molluscs and crustaceans). Regressions were obtained for 134 insect genera (155 species) and 153 total invertebrate genera (184 species). Regressions are provided for both body length and head width for some taxa. In some cases, regressions are provided from multiple localities for single taxa. When using body length in the equations, there were no significant differences in the mean value of the exponent b among 8 insect orders or Amphipoda. The mean value of b for insects was 2.79, ranging from only 2.69 to 2.91 among orders. The mean value of b for Decapoda (3.63), however, was significantly higher than all insects orders and amphipods. Mean values of a were not significantly different among the 8 insect orders and Amphipoda, reflecting considerable variability within orders. Reasons for potential differences in b among taxa are explained with hypothetical examples showing how b responds to changes in linear dimensions and specific gravity. When using head width as the linear dimension in the power model, the mean value of b was higher (3.11) than for body length and more variable among orders (2.8-3.3). Values of b for Ephemeroptera (3.3) were significantly higher than those for Odonata, Megaloptera, and Diptera. For those equations in which ash-free dry mass was used, % ash varied considerably among functional feeding groups (3.3-12.4%). Percent ash varied from 4.0% to 8.5% among major insect orders, but was 18.9% for snails (without shells). Family-level regressions also are presented so that they can be used when generic equations are unavailable or when organisms are only identified to the family level. It is our intention that these regressions be used by others in estimating mass from linear dimensions, but potential errors must be recognized.

Benke, A.C., and J.B. Wallace. 1980. Trophic basis of production among net-spinning caddisflies in a southern Appalachian stream. Ecology 61: 108-118.

Abstract
Life histories and annual production were determined for six species of net-spinning caddisflies in a headwater stream of the Tallulah River in north Georgia. Five species in the family Hydropsychidae were univoltine, whereas the sixth, a member of the Philopotamidae, had at least two generations per year. Seventy-five percent of the annual production was concentrated in the two largest species, Arctopsyche irrorata and Parapsyche cardis. Analysis of gut contents indicated that detritus was the most important food source. However, almost 80 percent of all caddisfly production was attributed to animal food. Net-spinning caddisfly production in this mountain stream appears to be limited by the amount of high-quality food available in the seston.

Benstead, J., Rosemond, A., Cross, W., Wallace, J., Eggert, S., Suberkropp, K., Gulis, V., Greenwood, J., Tant, C. 2009. Nutrient enrichment alters storage and fluxes of detritus in a headwater stream ecosystem. Ecology, 90(9):2556-2566

Abstract
Responses of detrital pathways to nutrients may differ fundamentally from pathways involving living plants: basal carbon resources can potentially decrease rather than increase with nutrient enrichment. Despite the potential for nutrients to accelerate heterotrophic processes and fluxes of detritus, few studies have examined detritus–nutrient dynamics at whole-ecosystem scales. We quantified organic matter (OM) budgets over three consecutive years in two detritus-based Appalachian (USA) streams. After the first year, we began enriching one stream with low-level nitrogen and phosphorus inputs. Subsequent effects of nutrients on outputs of different OM compartments were determined using randomized intervention analysis. Nutrient addition did not affect dissolved or coarse particulate OM export but had dramatic effects on fine particulate OM (FPOM) export at all discharges relative to the reference stream. After two years of enrichment, FPOM export was 340% higher in the treatment stream but had decreased by 36% in the reference stream relative to pretreatment export. Ecosystem respiration, the dominant carbon output in these systems, also increased in the treatment stream relative to the reference, but these changes were smaller in magnitude than those in FPOM export. Nutrient enrichment accelerated rates of OM processing, transformation, and export, potentially altering food-web dynamics and ecosystem stability in the long term. The results of our large-scale manipulation of a detrital ecosystem parallel those from analogous studies of soils, in which net loss of organic carbon has often been shown to result from experimental nutrient addition at the plot scale. Streams are useful model systems in which to test the effects of nutrients on ecosystem-scale detrital dynamics because they allow both the tracking of OM conversion along longitudinal continua and the integrated measurement of fluxes of transformed material through downstream sites.

Benstead, Jonathan P., and David S. Leigh, 2012, An Expanded Role for River Networks. Nature Geoscience 5:678-679.

Abstract
Estimates of stream and river area have relied on observations at coarse resolution. Consideration of the smallest and most dynamic streams could reveal a greater role for river networks in global biogeochemical cycling than previously thought.

Berdanier, A. and J.S. Clark. 2016. Multi-year drought-induced morbidity preceding tree death in Southeastern US forests. Ecological Applications 26(1):17-23. doi: 10.1890/15-0274.1

Abstract
Recent forest diebacks combined with threats of future drought focus attention on the extent to which tree death is caused by catastrophic events as opposed to chronic declines in health that accumulate over years. While recent attention has focused on large-scale diebacks, there is concern that increasing drought stress and chronic morbidity may have pervasive impacts on forest composition in many regions. Here we use long-term, whole-stand inventory data from Southeastern US forests to show that trees exposed to drought experience multi-year declines in growth prior to mortality. Following a severe, multi-year drought, 72% of trees that did not recover their pre-drought growth rates died within 10 years. This pattern was mediated by local moisture availability. As an index of morbidity prior to death, we calculated the difference in cumulative growth after drought relative to surviving conspecifics. The strength of drought-induced morbidity varied among species and was correlated with drought tolerance. These findings support the ability of trees to avoid death during drought events but indicate shifts that could occur over decades. Tree mortality following drought is predictable in these ecosystems based on growth declines, highlighting an opportunity to address multi-year drought-induced morbidity in models, experiments, and management decisions

Berdanier, A. B. and Clark, J. S. (2018), Tree water balance drives temperate forest responses to drought. Ecology, 99: 2506-2514. doi:10.1002/ecy.2499

Abstract
Intensifying drought is increasingly linked to global forest diebacks. Improved understanding of drought impacts on individual trees has provided limited insight into drought vulnerability in part because tree moisture access and depletion is difficult to quantify. In forests, moisture reservoir depletion occurs through water use by the trees themselves. Here, we show that drought impacts on tree fitness and demographic performance can be predicted by tracking the moisture reservoir available to trees as a mass balance, estimated in a hierarchical state-space framework. We apply this model to multiple seasonal droughts with tree transpiration measurements to demonstrate how species and size differences modulate moisture availability across landscapes. The depletion of individual moisture reservoirs can be tracked over the course of droughts and linked to biomass growth and reproductive output. This mass balance approach can predict individual moisture deficit, tree demographic performance, and drought vulnerability throughout forest stands based on measurements from a sample of trees.

Berdanier, A. B., and J. S. Clark. 2016. Divergent reproductive allocation trade-offs with canopy exposure across tree species in temperate forests. Ecosphere 7(6):e01313. 10.1002/ecs2.1313

Abstract
Variation in tree reproduction can alter forest community dynamics, especially if reproductive output is costly for other functions like growth. However, empirical studies reach con?icting conclusions about the constraints on reproductive allocation relative to growth and how they vary through time, across species, and between environments. Here, we test the hypothesis that a critical resource, canopy exposure to light availability, limits reproductive allocation by comparing long-term relationships between reproduction and growth for trees from 21 species in forests throughout the Southeastern United States. We found that species have divergent responses to light availability, with shade-intolerant species experiencing an alleviation of trade-offs at high light- and shade-tolerant species showing no changes in reproductive output across light environments. Correlations between temporal variation in individual growth and reproduction were weak and generally insensitive to canopy exposure, but changed when considering time lags. The diversity of responses across species indicates that reproductive allocation for trees in these forests is strongly influenced by both species’ life history and environmental heterogeneity in space and time.

Berdanier, Aaron B., Chelcy F. Miniat, and James S. Clark, (2016) Predictive models for radial sap flux variation in coniferous, diffuse-porous and ring-porous temperate trees Tree Physiol. 36 (8): 932-941 doi:10.1093/treephys/tpw027

Abstract
Accurately scaling sap flux observations to tree or stand levels requires accounting for variation in sap flux between wood types and by depth into the tree. However, existing models for radial variation in axial sap flux are rarely used because they are difficult to implement, there is uncertainty about their predictive ability and calibration measurements are often unavailable. Here we compare different models with a diverse sap flux data set to test the hypotheses that radial profiles differ by wood type and tree size. We show that radial variation in sap flux is dependent on wood type but independent of tree size for a range of temperate trees. The best-fitting model predicted out-of-sample sap flux observations and independent estimates of sapwood area with small errors, suggesting robustness in the new settings. We develop a method for predicting whole-tree water use with this model and include computer code for simple implementation in other studies.

Berglund, E.R. 1989. Forest Hydrology and Ecology at Coweeta. Water Resources Bulletin 25(2): 455-458.

Abstract
A review of the Coweeta Symposium volume.

Berish, C.W., and H.L. Ragsdale. 1984. Chronological sequence of element concentrations in wood of Carya spp. in the southern Appalachian Mountains. Canadian Journal of Forest Research. 15: 477-483.

Abstract
Tree-ring analyses of hickory (Carya spp.) from the long-term ecological research site, Coweeta Hydrologic Research Laboratory, revealed that concentrations (micrograms per gram) of lead, aluminum, and zinc are increasing, that concentrations of copper, cadmium, nickel, and manganese have remained generally constant since the 1880's, and that hickory annual radial growth increments are declining. Lead, aluminum, and zinc burdens (microgram per growth interval), unlike their respective concentrations, have remained generally constant during the 1900's. The interpretation of growth and burden data indicates that hickory trees at Coweeta are in a mature phase of their life cycle and that annual growth does not seem to be reduced by pollutants.

Berish, C.W., and H.L. Ragsdale. 1986. Metals in low-elevation, Southern Appalachian forest floor and soil. Journal of Environmental Quality 15(2): 183-187.

Abstract
Concentrations of Ca, K, Mg, Mn, Cd, Co, Cu, Pb, and Zn in southern Appalachian soils from two 90-yr-old forests were determined by three extraction methods. Total soil Ca, K, Mg, and Mn pools were two or more orders of magnitude greater than trace metal pools. Fractions of the total metal pools that were readily and potentially available generally decreased in depth. Litter and humus trace metal concentrations of two low elevation watersheds in the Coweeta Basin contain lower concentrations of Cu, Zn, and Pb than commonly reported for the northeastern USA. The largest trace metal pool in forest floor litter and humus was lead.

Bernot, M. J., D. J. Sobota, R. O. Hall, Jr, P. J. Mulholland, W. K. Dodds, J. R. Webster, J. L. Tank, L. R. Ashkenas, L. W. Cooper, C. N. Dahm, S. V. Gregory, N. B. Grimm, S. K. Hamilton, S. L. Johnson, W. H. McDowell, J. L. Meyer, B. Peterson, G. C. Poole, H. M. Valett, et al. 2010. Inter-regional comparison of land-use effects on stream metabolism. Freshwater Biology, 55: 1874-1890.

Abstract
1. Rates of whole-system metabolism (production and respiration) are fundamental indicators of ecosystem structure and function. Although first-order, proximal controls are well understood, assessments of the interactions between proximal controls and distal controls, such as land use and geographic region, are lacking. Thus, the influence of land use on stream metabolism across geographic regions is unknown. Further, there is limited understanding of how land use may alter variability in ecosystem metabolism across regions. 2. Stream metabolism was measured in nine streams in each of eight regions (n = 72) across the United States and Puerto Rico. In each region, three streams were selected from a range of three land uses: agriculturally influenced, urban-influenced, and reference streams. Stream metabolism was estimated from diel changes in dissolved oxygen concentrations in each stream reach with correction for reaeration and groundwater input. 3. Gross primary production (GPP) was highest in regions with little riparian vegetation (sagebrush steppe in Wyoming, desert shrub in Arizona /New Mexico) and lowest in forested regions (North Carolina, Oregon). In contrast, ecosystem respiration (ER) varied both within and among regions. Reference streams had significantly lower rates of GPP than urban or agriculturally influenced streams. 4. GPP was positively correlated with photosynthetically active radiation and autotrophic biomass. Multiple regression models compared using Akaike’s information criterion (AIC) indicated GPP increased with water column ammonium and the fraction of the catchment in urban and reference land-use categories. Multiple regression models also identified velocity, temperature, nitrate, ammonium, dissolved organic carbon, GPP, coarse benthic organic matter, fine benthic organic matter and the fraction of all land-use categories in the catchment as regulators of ER. 5. Structural equation modelling indicated significant distal as well as proximal control pathways including a direct effect of land-use on GPP as well as SRP, DIN, and PAR effects on GPP; GPP effects on autotrophic biomass, organic matter, and ER; and organic matter effects on ER. 6. Overall, consideration of the data separated by land-use categories showed reduced inter-regional variability in rates of metabolism, indicating that the influence of agricultural and urban land use can obscure regional differences in stream metabolism.

Biswell, H.H., and M.D. Hoover. 1945. Appalachian hardwood trees browsed by cattle. Journal of Forestry 43: 675-676.

Abstract
Cattle are selective in the tree species they browse. Percentage breakdowns by species are given for the foliage eaten by cattle on a 145-acre Appalachian watershed during 1941 and 1942. Herb utilization approached 100 percent after 1 year of grazing, and the grazing capacity of the watershed was reduced by 50 percent during 1 year of browsing.

Bjorkland, R., C.M. Pringle, and B. Newton. 2001. A stream visual assessment protocol (SVAP) for riparian landowners. Environmental Monitoring and Assessment 68: 99-125.

Abstract
A user-friendly Stream Visual Assessment Protocol (SVAP) was recently developed in a joint effort by the Natural Resources Conservation Service (NRCS) of the U.S. Department of Agriculture and the University of Georgia. SVAP was designed to be an introductory screening–level assessment method for people unfamiliar with stream assessments. It was designed for use by NRCS field staff who work with agricultural landowners. NRCS is in a key position to influence conservation practices since the organization works with private stakeholders, maintaining more than 2000 field offices throughout the U.S. with a central office in each state. The SVAP measures a maximum of 15 elements and is based on visual inspection of the physical and biological characteristics of instream and riparian environments. Each element is assigned a numerical score relative to reference conditions and an overall score for the stream reach is calculated. A qualitative description of the stream reach is made based on overall numerical score. While SVAP is not intended to replace more robust stream assessment protocols, it provides quick and reliable information for use in NRCS farm assistance programs. It is also an educational tool through which landowners can learn about conservation of aquatic resources. An abridged copy of SVAP is attached as an appendix to this article and the complete document can be found on the web at http://www.ncg.nrcs.usda.gov/tech_notes.html.

Black, P.E. 1959. Interception of rainfall by a hardwood canopy. University of Istanbul, Orman Fakultesi: Dergisi 9(2): 218-224.

Abstract
Results of studying rainfall intercepted by cove hardwoods growing on an old field are discussed, and equations for determining throughfall during fall, winter, spring, and summer are presented. Estimates of the number of throughfall gages required for interception studies in similar stands are given.

Blair, J.M. 1988. Nitrogen, sulfur and phosphorus dynamics in decomposing deciduous leaf litter in the Southern Appalachians. Soil Biology and Biochemistry 20(5): 693-701.

Abstract
The decomposition rates and N, S and P dynamics of flowering dogwood, red maple and chestnut oak litter were examined during 2 years in a mixed deciduous forest. Litter of flowering dogwood decomposed the fastest and chestnut oak the slowest. Initial mass losses (first 6 months) were most highly positively correlated with concentrations of ethanol-soluble and total soluble components. First-year annual decay rates were most highly negatively correlated with initial % lignin and lignin-to-N ratios. Second-year decay rates were significantly slower than first-year rates for flowering dogwood and red maple litter, but not for chestnut oak. Relative concentrations of N, S and P increased during the decomposition of each litter type. Nitrogen release began when C-to-N ratios decreased to between 25 and 34. Patterns of P and S fluxes varied more among litter types. Only dogwood litter appeared to release P by the end of the study. Flowering dogwood litter also had a low initial C-to-S ratio and displayed an immediate net release of S which continued throughout the study. The other litter types, which had higher initial C-to-S ratios, immobilized S throughout the study.

Blair, J.M. 1988. Nutrient release from decomposing foliar litter of three tree species with special reference to calcium, magnesium and potassium dynamics. Plant and Soil 110: 49-55.

Abstract
Calcium, magnesium and potassium dynamics in decomposing litter of three tree species were measured over a two-year period. The species studied were flowering dogwood, red maple and chestnut oak. The order of decomposition was: C. florida > A. rubrum > Q. prinus. Calcium concentrations increased following initial leaching losses. There were net releases of Ca from all three litters since mass loss exceeded increases in concentration. Net release of Ca by the end of two years was 42% of initial inputs in litterfall. Magnesium concentrations increased in the second year, following decreases due to leaching during the first year. Net release of Mg by the end of two years was 58% of initial inputs. Potassium concentrations decreased rapidly and continued to decline throughout the study. Net release of K by the end of two years was 91% of initial inputs. These and similar data on N, S and P dynamics were combined with annual litterfall data to estimate the release of nutrients from litter at the end of one and two years of decomposition. The relative mobility of all six elements in relation to mass loss after two years was K > Mg > mass > Ca > S > P > N.

Blair, J.M., and D.A. Crossley Jr. 1988. Litter decomposition, nitrogen dynamics and litter microarthropods in a Southern Appalachian hardwood forest 8 years following clearcutting. Journal of Applied Ecology 25: 683-698.

Abstract
Litter decomposition rates, nitrogen dynamics and litter microarthropods on xeric slopes of a watershed 8 years after clearcutting (WS 7) and on an adjacent reference watershed (WS 2) at Coweeta were measured using litterbags containing Cornus florida L., Acer rubrum L. and Quercus prinus L. Results from this study were compared with those for earlier studies to assess the longer-term changes induced by canopy removal. Reduced litter decomposition rates and net immobilization of nitrogen in litter substrates were associated with clearcutting. Mean annual densities of total litter microarthropods remained 28% lower on WS 7 than on WS 2, 8 years after cutting; clearcutting initially reduced mean annual densities of litter microarthropods by >50%. Relative abundances of major groups were altered. Mesostigmata and Oribatei densities averaged 50 and 54% lower, respectively, than on WS 2. Prostigmata and Collembola densities averaged 20 and 24% lower, respectively, than on WS 2. Changes in litter decomposition rates and nitrogen dynamics were consistent with lower microarthropod densities. Results of this study differ from those at northern hardwood forest sites where clearcutting caused increased decomposition rates, thus generalizations from northern hardwood forests may not apply to other regions.

Blair, J.M., D. Crossley Jr., and L.C. Callaham. 1991. A litterbasket technique for measurement of nutrient dynamics in forest floors. Agriculture, Ecosystems and Environment 34: 465-471.

Abstract
This describes a litterbasket technique for quantifying decomposition and changes in litter and forest floor nutrient pools over time. Litterbaskets are constructed of wire cloth, 10x10x10 cm. Intact cores, removed from forest floors, are separated into individual strata (litter layer, F-layer, soil) with plastic window screen. The core is reassembled in the litterbasket, which is replaced in the hole from which the core was removed. Pre-weighed aliquots of experimental substrates can replace the litter layer. The advantages of the litterbasket method include: (1) improved microclimatic exposure relative to litter enclosed in litterbags; (2) opportunity to input exogenous radioactive or stable isotopetracers; (3) quantification of changes in nutrient contents in the various layers of the forest floor over time; (4) easy extraction of invertebrates and quantification of microbial populations from individual horizons; (5) the ability to quantify the movement of radioactive or stable tracers from litter through the forest floor profile over time.

Blair, J.M., D.A. Crossley Jr., and L.C. Callaham. 1992. Effects of litter quality and microarthropods on N-dynamics and retention of exogenous N-15 in decomposing litter. Biol. Fert. Soils 12: 241-252.

Abstract
Surface additions of (15NH4)2SO4 were used to measure the immobilization an subsequent movement of exogenous N added to two litter types of contrasting quality (Cornus florida and Quercus prinus). Litterbaskets were used to measure the litter mass loss and N dynamics and to follow the movement of the 15N label through litter, F layer, and soil pools. Half of the litterbaskets of each species were treated with naphthalene to reduce microarthropod densities. The faster decomposing C. florida litter maintained a higher excess atom % 15N , and a greater relative concentration of the labeled input (+g15Ng-1) than did Q. prinus litter. In both litter types the excess atom % 15N, relative concentration (+g15Ng-1), and absolute amount of label recovered in the litter declined over time. This occurred during a period of net accumulation of total litter N, implying simultaneous release of the initial input and immobilization of N from other sources. The concentration of 15N in the soil increased over time, while the f layer apparently acted as an intermediary in the transfer of 15N from litter to soil. Naphthalene effectively reduced microarthrop numbers in all horizons of the litterbaskets and significantly reduced the decay rates of Q. prinus, but not C. florida litter. Naphthalene did not appear to affect total n dynamics in the litter. However, with all horizons taken together, the naphthalene-treated litterbaskets retained more total 15N than the control litterbaskets. Naphthalene also changed the vertical distribution o 15N within litterbaskets, so that the litter retained less of the 15N-label input and the F layer and soil horizons retained more of the labeled input than in control litterbaskets. Our major conclusions are: (1) the N pool of decomposing litter is dynamic, with simultaneous N release and immobilization activating N turnover even during the net accumulation phase; (2) litter quality is an important determinant of immobilization and retention of exogenous N inputs and, therefore, turnover of the litter N pool; and (3) microarthropod activity can significantly affect the incorporation and retention of exogenous N inputs in decomposing litter, although these changes are apparently not reflected in net N accumulation or release during the 1st year of decomposition. However, the naphthalene may have affected microbially mediated N dynamics and this possibility needs to be considered in interpreting the results.

Blair, J.M., D.A. Crossley Jr., and S. Rider. 1989. Effects of naphthalene on microbial activity and nitrogen pools in soil-litter microcosms. Soil Biology and Biochemistry 21(4): 507-510.

Abstract
Results suggest that naphthalene may directly affect microbial populations and activity and alter nitrogen dynamics and that caution should be used in interpreting results of field studies using naphthalene to exclude microarthropods. Naphthalene was applied three times during a 56 day study of microbial respiration, numbers of bacteria and fungi, and litter and soil nitrogen pools in litter-soil microcosms containing microbes but no mesofauna. Total respiration was unaffected by the first application of naphthalene, but increased upon subsequent applications. Bacteria and fungi in the litter and soil were quantified separately. Numbers of bacteria were significantly higher in both litter and soil of naphthalene-treated microcosms. Lengths of total and FDA-active fungal hyphae in the litter and soil, respectively, were significantly lower in the naphthalene treatment. Mass loss of litter was not affected. Both the final concentration and absolute amount of N in the litter were reduced by naphthalene, as was soil extractable NH4-N and NO3- + NO2-N.

Blair, J.M., R.W. Parmelee, and M.H. Beare. 1990. Decay rates, nitrogen fluxes, and decomposer communities of single- and mixed-species foliar litter. Ecology 71(5): 1976-1985.

Abstract
Decomposition rates, N fluxes, and abundances of decomposer organisms were quantified in mixed-species litterbags (containing leaves of Acer rubrum, Cornusflorida, and Quercus prinus) and in single species litterbags. Single-species litterbags were used to generate predicted decay rates, N fluxes, and abundances of decomposer organisms for mixed-species litterbags. Observed values from mixed bags were compared with predicted to determine if interaction effects occurred. Decay rates of mixed species litterbags during the 1-yr study were not significantly different than predicted from decay rates of individual component species. However, there were significant interaction effects on N fluxes and abundances of decomposer organisms. For example, estimates of ecosystem-level N fluxes, based on data from single-species litterbags, resulted in a 64% underestimate of N released by day 75 and a 183% overestimate of N accumulated in the litter by day 375. The deviation of observed N fluxes from predicted may be the result of differences in the decomposer community.

Block, C., Knoepp, J.D. and Fraterrigo, J.M. 2013. Interactive effects of disturbance and nitrogen availability on phosphorus dynamics of southern Appalachian forests. Biogeochemistry. 112:329-342. (DOI: 10.1007/s10533-012-9727-y)

Abstract
Understanding the main and interactive effects of chronically altered resource availability and disturbance on phosphorus (P) availability is increasingly important in light of the rapid pace at which human activities are altering these processes and potentially introducing P limitation. We measured P pools and fluxes in eighteen mixed forest stands at three elevations (low, mid, high) subjected to increasing atmospheric N deposition, where hemlock (Tsuga canadensis) was absent or declining due to infestation by the exotic hemlock woolly adelgid (Adelges tsugae). While total soil P was similar across the study area, phosphorus fractionation revealed distinct differences in the distribution of soil P fractions as elevation and N availability increased. Soils from high elevation plots where N availability was greatest had 139 % larger organic P pools and 55 % smaller residual and refractory P pools than soils from low elevation plots with less N availability, suggesting that increased N availability has driven the depletion of recalcitrant P pools by stimulating biotic demand and sequestration. These differences in P distribution among fractions influenced how tree mortality affected P dynamics. At high elevations, plots containing declining hemlocks had significantly greater foliar P concentrations and fluxes of P from the forest floor than reference plots at similar elevations, whereas at low and mid-elevations there were no consistent differences between plots. Across all elevation classes, hardwood foliar N:P ratios were lower in plots with declining hemlocks. Collectively, these results suggest that increased N availability enhances bioavailable P, which is sequestered in vegetation until disturbances liberate it.

Block, C., Knoepp, J.D., Elliott, K. and Fraterrigo, J.M. 2012. Impacts of Hemlock Loss on Nitrogen Retention Vary with Soil Nitrogen Availability in the Southern Appalachian Mountains. Ecosystems. 15(7):1108-1120. (DOI: 10.1007/s10021-012-9572-9)

Abstract
The impacts of exotic insects and pathogens on forest ecosystems are increasingly recognized, yet the factors influencing the magnitude of effects remain poorly understood. Eastern hemlock (Tsuga canadensis) exerts strong control on nitrogen (N) dynamics, and its loss due to infestation by the hemlock woolly adelgid (Adelges tsugae) is expected to decrease N retention in impacted stands. We evaluated the potential for site variation in N availability to influence the magnitude of effects of hemlock decline on N dynamics in mixed hardwood stands. We measured N pools and fluxes at three elevations (low,mid, high) subjected to increasing atmospheric N deposition where hemlock was declining or absent (as reference), inwestern North Carolina. Nitrogen pools and fluxes varied substantially with elevation and increasing N availability. Total forest floor and mineral soil N increased (P < 0.0001, P = 0.0017, resp.) and forest floor and soil carbon (C) to N ratio decreased with elevation (P < 0.0001, P = 0.0123, resp.), suggesting that these high elevation pools are accumulating available N. Contrary to expectations, subsurface leaching of inorganic N was minimal overall (<1 kg ha-1 9 months-1), and was not higher in stands with hemlock mortality. Mean subsurface flux was 0.16 ± 0.04 (SE) (kg N ha-1 100 days-1) in reference and 0.17 ± 0.05 (kg N ha-1 100 days-1) in declining hemlock stands. Moreover, although subsurface N flux increased with N availability in reference stands, there was no relationship between N availability and flux in stands experiencing hemlock decline. Higher foliar N and observed increases in the growth of hardwood species in high elevation stands suggest that hemlock decline has stimulated N uptake and growth by healthy vegetation within this mixed forest, and may contribute to decoupling the relationship between N deposition and ecosystem N flux.

Boll, Jan, Erin S. Brooks, Brian Crabtree, Shuhui Dun, and Tammo S. Steenhuis, 2015. Variable Source Area Hydrology Modeling with the Water Erosion Prediction Project Model. Journal of the American Water Resources Association (JAWRA) 51(2): 330-342. DOI: 10.1111/1752-1688.12294.

Abstract
In nondegraded watersheds of humid climates, subsurface flow patterns determine where the soil saturates and where surface runoff is occurring. Most models necessarily use infiltration-excess (i.e., Hortonian) runoff for predicting runoff and associated constituents because subsurface flow algorithms are not included in the model. In this article, we modify the Water Erosion Prediction Project (WEPP) model to simulate subsurface flow correctly and to predict the spatial and temporal location of saturation, the associated lateral flow and surface runoff, and the location where the water can re-infiltrate. The modified model, called WEPP-UI, correctly simulated the hillslope drainage data from the Coweeta Hydrologic Laboratory hillslope plot. We applied WEPP-UI to convex, concave, and S-shaped hillslope profiles, and found that multiple overland flow elements are needed to simulate distributed lateral flow and runoff well. Concave slopes had the greatest runoff, while convex slopes had the least. Our findings concur with observations in watersheds with saturation-excess overland flow that most surface runoff is generated on lower concave slopes, whereas on convex slopes runoff infiltrates before reaching the stream. Since the WEPP model is capable of simulating both saturation-excess and infiltration-excess runoff, we expect that this model will be a powerful tool in the future for managing water quality.

Bolstad, P. V., K. J. Elliott, and C. F. Miniat. 2018. Forests, shrubs, and terrain: top-down and bottom-up controls on forest structure. Ecosphere 9(4):e02185. 10.1002/ecs2.2185

Abstract
Overstory forest structure responds to terrain-related abiotic factors and to biotic interactions among overstory and understory plants. Unlike species abundance, tree height, biomass, and leaf area in many regions have been poorly quantified in relation to terrain-driven environmental gradients. In addition, the magnitude of understory influences on overstory structure has been poorly characterized for many forest systems. Our primary goal was to identify relationships between terrain (elevation, convexity, exposure), evergreen understory, and overstory structure (height, aboveground biomass, leaf area) in mature deciduous forests of the southern Appalachian Mountains. We used a combination of field point and plot measurements, LiDAR, and satellite image data to sample little-disturbed deciduous forest stands. Height, biomass, and gap frequency were significantly related to changes in elevation, exposure (aspect), and convexity (cove to ridge). Higher evergreen understory density was strongly correlated with decreases in forest height and biomass, with an impact observed across moisture, elevation, and exposure gradients. Canopies on ridges averaged half as tall at the highest evergreen understory densities when compared to those without evergreen shrubs (10 vs. 19 m), and overstory canopy height averaged 6 m shorter on sideslopes with high evergreen understory density compared to those with low evergreen understory density. Canopy height declined from low to high elevations, with larger relative decreases on ridges, but biomass increased from low to high elevations, due primarily to high biomass in coves at mid- to upper elevations. Biomass and canopy height declined from cove to ridge and north- to south-facing slopes. Responses in canopy height and aboveground biomass associated with changes in understory evergreen density were similar to impacts due to terrain. Gaps were more frequent on south-facing slopes. Previous studies at this site and others identify soil moisture and soil N competition as the most plausible mechanisms by which understory shrubs might influence overstory canopy structure, with low light limiting seedling recruitment as an additional mechanism. Our work suggests evergreen understory density, particularly on sideslope and ridge locations, substantially affects overstory canopy height and biomass.

Bolstad, P.V., and J.M. Vose. 2005. Forest and Pasture Carbon Pools and Soil Respiration in the Southern Appalachian Mountains. Forest Science. 51(4): 372-383.

Abstract
Our ability to estimate the changes in carbon (C) pools and fluxes due to forest conversion is hampered by a lack of comparative studies. We measured above- and belowground C pools and soil respiration flux at four forested and four pasture sites in the southern Appalachian Mountains. Above- and belowground C pools were significantly larger (P < 0.01, t-test) at forested sites relative to pasture sites. The largest differences were in aboveground live biomass, which averaged 152 Mg ha-' C at the forested sites and 1.9 Mg ha-' at the pasture sites. Coarse root and stump C and surface detritus were also substantially different, averaging 41.3 and 32.6 Mg ha-' C, respectively, at the forested sites, and less than 1 Mg ha-' at the pasture sites. Fine root C was higher and mineral soil C lower at pasture sites relative to comparable forested sites, but neither difference was statistically significant. Soil respiration at a given temperature was generally lower at pasture sites relative to forest sites. However, soil temperatures at pastures were consistently higher than at forest sites. Estimated annual soil respiration flux averaged 10.9 Mg C ha- ' at the pasture sites and 12.6 Mg C ha-' at the forested sites.

Bolstad, P.V., and T.L. Gragson. 2008. Resource abundance constraints on the early post-contact Cherokee population. Journal of Archeological Science 35:563-576.

Abstract
We present the combination of an analysis of resource demand by the early post-contact (1721) Cherokee population with spatially explicit estimates of production for five key resources: architectural land, agricultural land, firewood, hard mast, and white-tailed deer (Odocoileus virginianus). We combine a recent synthesis of village location and population, a map of recognized Cherokee territory, digital terrain data, estimates of per capita demand, and productive capacity for each resource. Average, high, and low demands were estimated for each resource and assigned based on a weighted function of terrain and distance from each village. We conclude that Cherokee demands for architectural and agricultural land, hard mast, and fuelwood were easily met within a short proximity to each town under all combinations of production and demand. These resources were likely not limiting, and were satisfied for the entire Cherokee population by less than 1% of the entire recognized Cherokee territory in 1721. These resources likely exceeded demand even when sources were restricted to the convex hull of the Cherokee territory, or to near stream, flat regions. Deer resources were likely harvested over a much larger area and to a much greater extent. Our best estimate of deer resource demand was 32% of annual sustainable production in the Cherokee territory, with from 16 to 48% of estimated sustainable production harvested for low and high demand estimates, respectively. Our estimates vary in response to uncertainties in deer production, harvest proportion, deer density, and sustainable harvest rates. Deer demand was substantially higher under all combinations of conditions than that available within the convex hull of Cherokee villages, indicating significant travel was needed to furnish deer requirements. Spatially explicit models that consider terrain- and distance-related tradeoffs suggest that Cherokee demand for deer drove harvest over areas consisting of over half the recognized Cherokee territory.

Bolstad, P.V., and W.T. Swank. 1997. Cumulative impacts of landuse on water quality in a southern Appalachian watershed. Journal of the American Water Resources Association. 33(3): 519-533.

Abstract
Water quality variables were samples over 109 weeks along Coweeta Creek, a fifth-order stream located in the Appalachian mountains of western North Carolina. The purpose of this study was to observe any changes in water quality, over a range of flow conditions, with concomitant downstream changes in the mix of landuses. Variables sampled include pH, HCO32-, conductivity, NO3-_N, NH4+_N, PO43-_P, Cl-, Na+, K+, Ca2+, Mg2+, SO42-, SiO2, turbidity, temperature, dissolved oxygen, total and fecal coliform, and fecal streptococcus. Landcover/ landuse was interpreted from 1:20,000 aerial photographs and entered in a GIS, along with information on total and paved road length, building location and density, catchment boundaries, hydrography, and slope. Linear regressions were performed to relate basin and near- stream land-scape variables to water quality. Consistent, cumulative, downstream changes in water quality variables were observed along Coweeta Creek, concomitant with downstream, human-caused changes in landuse. Furthermore, larger downstream changes in water quality variables were observed during stormflow when compared to baseflow, suggesting cumulative impacts due to landscape alteration under study conditions were much greater during storm events. Although most water quality regulations, legislation, and sampling are promulgated for baseflow conditions, this work indicates they should also consider the cumulative impacts of physical, chemical, and biological water quality during stormflow.

Bolstad, P.V., K. Mitchell, and J.M. Vose. 1999. Foliar temperature-respiration response functions for broad-leaved tree species in the southern Appalachians. Tree Physiology. 19: 871-878

Abstract
We measured leaf respiration in 18 eastern deciduous forest tree species to determine if there were differences in temperature-respiration response functions among species or among canopy positions. Leaf respiration rates were measured in situ and detached branches for Acerpensylvanicum L., A. rubrum L., Betula spp. (B. alleghaniensis Britt. and B. lenta L.), Carya glabra (Mill.) Sweet, Cornus florida L., Fraxinus spp. (primarily F. americana L.), Liriodendron tulipifera L., Magnolia fraseri Walt., Nyssa sylvatica Marsh., Oxydendrum arboreum L., Platanus occidentalis L., Quercu alba L., Q. coccinea Muenchh., Q. prinus L., Q rubra L., Rhododendron maximum L., Robinia psuedoacacia L., and Tilia americana L. in the southern Appalachian Mountains, USA.

Bolstad, P.V., L. Swift, F. Collins, and J. Regniere. 1998. Measured and predicted air temperatures at basin to regional scales in the southern Appalachian mountains. Agricultural and Forest Meteorology. 91: 161-176.

Abstract
Landscape and temporal patterns of temperature were observed for local and regional networks in the southern Appalachian Mountains of North America. Temperatures decreased with altitude at mean rates of 7+C/km and 3+C/km. Daily lapse rates depended on the method and stations used in the calculations. Average daily temperature ranges decreased as elevation increased, from 14+C at 700 m to 7+C at 1440 m, and daily temperature ranges were typically higher in spring and fall at any given station. Daily maximum temperature above the forest canopy averaged 1.4+C higher at a south-facing station relative to a comparable northwest-facing station, and above-canopy daily minimum temperatures were depressed at a valley-bottom station. Regional regression models provided a more accurate estimates of station temperature than either kriging or local lapse models when tested using 35 National Climatic Data Center (NCDC) stations in the southern Appalachians. Data-splitting tests yielded mean absolute errors (MAE) from 1.39 to 2.30+C for predictions of daily temperatures. Ten-year biases for an independent data set collected at four stations in the Coweeta Basin ranged from -2.87 to 2.91+C for daily temperatures, with regional regression performing best, on average. However tests against another independent data set indicate regional regression and local lapse models were not significantly different, with mean biases averaged from -2.78 to 2.91+C for daily predicted temperatures.

Bolstad, P.V., W. Swank, J. Vose. 1998. Predicting Southern Appalachian overstory vegetation with digital terrain data. Landscape Ecology. 13: 271-283.

Abstract
Vegetation in mountainous regions responds to small-scale variation in terrain, largely due to effects on both temperature and soil moisture. However there are few studies of quantitative, terrain-based methods for predicting vegetation composition. This study investigated relationships between forest composition, elevation, and a derived index of terrain shape, and evaluates methods for predicting forest composition. Trees were measured on 406 permanent plots within the boundaries of the Coweeta Hydrologic Lab, located in the Southern Appalachian Mountains of western North Carolina, USA. All plots were in control watersheds, without human or major natural disturbance since 1923. Plots were 0.08 ha and arrayed on transects, with approximately 380 meters between parallel transects. Breast-height diameters were measured on all trees. Elevation and terrain shape were estimated for each plot. Density and basal area were summarized by species and by forest type. Plot data were combined with digital elevation data (DEM), and a derived index of terrain shape at two sampling resolutions: 30 m and 80 m sources. Vegetation maps were produced using each of four different methods: 1) linear regression with and without log transformations against elevation and terrain variables combined with cartographic overlay, 2) kriging, 3) co-kriging, and 4) a mosaic diagram. Predicted vegetation was compared to known vegetation at each of 77 independent, withheld data points, and an error matrix was determined for each mapping method. We observed strong relationships between some species and elevation and/or terrain shape. Cove and xeric oak/pine species basal areas were positively and negatively related to concave landscape locations, respectively, while species typically found in the mixed deciduous and northern hardwood types were not. Most northern hardwood species occurred more frequently and at higher basal areas as elevation increased, while most other species did not respond to elevation. The regression and mosaic diagram mapping approaches had significantly higher mapping accuracies than kriging and co-kriging. There were significant effects of DEM resolution on map accuracy, with maps based on 30 m DEM data significantly more accurate than those based on 80 m data. Taken together, these results indicate that both the mapping method and terrain data resolution significantly affect the resultant vegetation maps, even when using relatively high resolution data. Landscape or regional models based on 100 m or lower resolution terrain data may significantly under-represent terrain-related variation in vegetation composition.

Bolstad, Paul V., James M. Vose and Steven G. McNulty. 2000. Forest Productivity, Leaf Area, and Terrain in Southern Appalachian Deciduous Forests. Forest Science 47(3):419-427.

Abstract
Leaf area index (LAI) is an important structural characteristic of forest ecosystems which has been shown to be strongly related to forest mass and energy cycles and forest productivity. LAI is more easily measured than forest productivity, and so a strong relationship between LAI and productivity would be a valuable tool in forest management. While a linear relationship has been observed between LA1 and forest productivity, most ofthese data have been collected in needle-leaved evergreen stands. The generality and consistency of the relationship between LAI and productivity has not been as well established for deciduous forests. Leaf area index (LAI) and aboveground net primary production (ANPP) were measured on 16 forest stands in the southern Appalachian Mountains. These stands span a range of elevation, slope position, temperature, and moisture regimes. LAI averaged 5.8 m2 me2 and ranged from 2.7 to 8.2. ANPP averaged 9.2 Mg ha-l yrl and ranged from 5.2 to II.8 Mg ha-l yrl. LAI and ANPP decreased significantly from cove to ridge sites, and ANPP decreases significantly from low to high elevation (P c 0.05, linear regression slope). Elevation-related differences in ANPP do not appear to be due to changes in precipitation, leaf nitrogen content, or site N mineralization rates. Linear ANPP-LAI equations fit to the data measured in this study were significant (P c 0.05). These relationships were not significantly different (P> 0.1) from linear relationships based on data reported in most other studies of ANPP and IAI in eastern deciduous forests of North America. However, the slope of a linear regression model based on North American eastern deciduous forests was significantly different (P < 0.05) from one based on data collected in temperate deciduous forests for the rest of the globe. The differences were slight over the range of observed data, however, and the difference may be due to a narrower range of data for North American deciduous forests.

Bonito, G.M., D.C. Coleman, B.L. Haines, and M.L. Cabrera. 2002. Can nitrogen budgets explain differences in soil nitrogen mineralization rates of forest stands along an elevations gradient? Forestry Ecology and Management. 176: 563-574.

Abstract
Nitrogen (N) mineralization rates in forest systems typically decrease with decreasing temperature. Temperature decreases with increasing elevation. Thus, N mineralization rates are expected to decrease with increasing elevation. However, soil N mineralization rates at the Coweeta Hydrologic Laboratory, NC, USA are higher at the highest elevation. Causes of higher mineralization rates at the higher elevation have yet to be explained. Alternative hypotheses to explain patterns of ineralization rates along this elevation gradient include (1) a mineralization promoter in decomposing herbs, leaf litter, or soil of the high elevation, (2) low pH in the low elevation soils which inhibit mineralization, (3) greater total N pools at the high elevation, (4) low moisture availability in low elevation soils, (5) differences in soil texture, and (6) differences in biological communities. Previous studies did not support our N mineralization promoter hypothesis, nor does soil pH explain mineralization rates. In this study we constructed N budgets for a high elevation northern hardwood and a low elevation oak-pine site to determine if differences in N pools and fluxes are sufficient to explain differences in N mineralization rates. Evaluating N in the upper 0- 10 cm of mineral soil, forest floor, overstory biomass, annual canopy litter fall, understory herb turnover, rainfall, canopy throughfall, and in soil solution, we found that the high elevation stand has more stored N and greater N fluxes than does the low elevation stand. The high elevation stand has many characteristics of a stand in an early stage of N saturation, while the low elevation stand characterizes an N-limited forest. Causes of greater N storages and fluxes at the high elevation northern hardwood site are not obvious.

Booth, D. B., Kraseski, K. A. and Rhett Jackson, C. (2014), Local-scale and watershed-scale determinants of summertime urban stream temperatures. Hydrol. Process., 28: 2427-2438. doi: 10.1002/hyp.9810

Abstract
The influence of urbanization on the temperature of small streams is widely recognized, but these effects are confounded by the great natural variety of their contributing watersheds. To evaluate the relative importance of local-scale and watershed-scale factors on summer temperatures in urban streams, hundreds of near-instantaneous temperature measurements throughout the central Puget Lowland, western Washington State, were collected during a single 2-h period in August in each of the years 1998–2001. Stream temperatures ranged from 8.9 to 27.5 C, averaging 15.4 C. Pairwise correlation coefficients between stream temperature and four watershed variables (total watershed area and the watershed percentages of urban development, upstream lakes, and permeable glacial outwash soils as an indicator of groundwater exchange) were uniformly very low. Akaike’s information criterion was applied to determine the best-supported sets of watershed-scale predictor variables for explaining the variability of stream temperatures. For the full four-year dataset, the only well-supported model was the global model (using all watershed variables); for the most voluminous single-year (1999) data, Akaike’s information criterion showed greatest support for per cent outwash (Akaike weight of 0.44), followed closely by per cent urban development + per cent outwash, per cent lake area only, and the global model. Upstream lakes resulted in downstream warming of up to 3 C; variability in riparian shading imposed a similar temperature range. Watershed urbanization itself is not the most important determining factor for summer temperatures in this region; even the long-recognized effects of riparian shading can be no more influential than those imposed by other local-scale and watershed-scale factors.

Boring, L., and W. Swank. 1984. The role of black locust (Robinia pseudo-acacia) in forest succession. Journal of Ecology 72: 749-766.

Abstract
Early forest regeneration in Southern Appalachian hardwood forests is dominated by the woody nitrogen-fixing legume, black locust. It is most prevalent on clear-felled areas, abandoned pastures, disturbed roadsides, and historically may have been an important colonizer of burned sites. It commonly reproduces from seed, but sprouting from stumps and roots is the most prevalent means of regeneration with rapid early growth, attaining heights up to 8 m in 3 years. Except for stands on high-nutrient sites, growth decreases after 10-20 years. In less vigorous stands, stem mortality may be high due to attacks by the locust stem borer. The high mortality of black locust is an early successional mechanism that releases codominant species such as Liriodendron, and creates canopy gaps favorable for growth of longer-lived individuals. Patterns of N accretion are similar to those for other woody nitrogen-fixing species with peak N fixation occurring in early to intermediate stages of forest succession, and declining with later successional development.

Boring, L.R., and W.T. Swank. 1984. Symbiotic nitrogen fixation in regenerating black locust (Robinia pseudo-acacia L.) stands. Forest Science 30(2): 528-537.

Abstract
Black locust is a dominant early successional tree in the Southern Appalachians that symbiotically fixes N, grows rapidly, and has a relatively short life span. Objectives of this research were to study seasonal patterns of nodule biomass and N-fixation activity in 4-year-old black locust stands over the span of one year, and to determine the importance of symbiotic N fixation as an input to a regenerating forest.

Boring, L.R., C.D. Monk, and W.T. Swank. 1981. Early regeneration of a clear-cut Southern Appalachian forest. Ecology 62: 1244-1253.

Abstract
The components of hardwood forest regeneration on a southern Appalachian watershed were assessed during the first year following clear-cutting. First-year net primary production (NPP) on the clear-cut was 22 percent of that of a nearby undisturbed hardwood forest. First-year nutrient pools in NPP for N, P, K, Mg, and Ca were estimated at 29 to 44 percent of those in the NPP of the control. The greatest NPP and nutrient pools were represented in descending order by hardwood sprouts, herbs, vines, and seedlings. The woody successional species had higher tissue concentrations of N and P than most other woody species. Herbs as a group had significantly higher foliar concentrations of K than woody species. Woody successional and herbaceous species collectively had higher biomass and elemental pools than other woody species. Following forest disturbance, these fast-growing species conserve substantial pools of nutrients in their biomass and initiate a rapid recovery of forest elemental cycling processes.

Boring, L.R., W.T. Swank, J.B. Waide, and G.S. Henderson. 1988. Sources, fates, and impacts of nitrogen inputs to terrestrial ecosystems: review and synthesis: Part 1 of 2. Biogeochemistry 6: 119-159.

Abstract
Rates of both symbiotic and nonsymbiotic nitrogen fixation appear to be greater during early successional stages of forest development and have major impacts on nitrogen dynamics and ecosystem productivity. Fates and impacts of these nitrogen inputs are important considerations that are inadequately understood. The relative importance of nitrogen inputs from atmospheric deposition and biological fixation is reviewed for non-agricultural terrestrial ecosystems. Bulk precipitation inputs of N are the same order of magnitude or larger than the inputs from nonsymbiotic fixation, especially in areas influenced by industrial activity. Bulk precipitation measurements may underestimate total atmospheric deposition by 30-40% because they generally do not include all forms of wet and dry deposition. Symbiotic fixation generally ranges from 10-160 kg N/ha/yr in ecosystems where N-fixing species are present during early successional stages. These input processes are highly variable in space and time. Specific needs for comparative information on both nitrogen deposition and fixation are suggested.

Bosch, J.M., and J.D. Hewlett. 1980. A review of catchment experiments to determine the effect of vegetation changes on water yield and evapotrasnpiration. Journal of Hydrology. 55: 3-23.

Abstract
This summary and review of 94 catchment experiments shows that accumulated information on the effect of vegetation changes on water yield can be used for practical purposes. The direction of change in water yield following forest operations can be predicted with fair accuracy since no experiments, with the exception of perhaps one, have resulted in reductions in water yield with reductions in cover, or increases in yield, with increases in cover. The approximate magnitude of changes can also be estimated. Pine and eucalypt forest types cause on average 40-mm change in water yield per 10% change in cover and deciduous hardwood and scrub ~25 and 10mm, respectively. Maximum changes of 660 mm were experienced at Coweeta, North Carolina. An assimilation of the collective experimental results shows that more careful design and expansion of experiments to certain rainfall regions would augment statistical inference.

Boullé, V., Grossman, G.D. 1991. Effects of Rosyside Dace (Clinostomus funduloides) on Microhabitat Use of Rainbow Trout (Oncorhynchus mykiss). Canadian Journal of Fisheries and Aquatic Sciences, 48(7): 1235-1243.

Abstract
We experimentally examined the effects of competition for space between rainbow trout (Oncorhynchus mykiss) and rosyside dace (Clinostomus funduloides) in an artificial stream. These species generally do not exhibit statistically significant differences in microhabitat use in Coweeta Creek, North Carolina, USA. Two competition (trout and dace) and two control (trout only) trials were conducted during spring and summer. Microhabitat use data indicated that the presence of dace did not produce microhabitat shifts in trout. Most behavioral changes could be attributed to acclimation effects or intraspecific competition. Based on field and laboratory results, it does not appear that interspecific competition with dace strongly affects the use of spatial resources in rainbow trout.

Boyer, J.S., and E.B. Knipling. 1965. Isopiestic technique for measuring leaf water potentials with a thermocouple psychrometer. Proceedings of the National Academy of Science 54(4): 1044-1051.

Abstract
This new technique for determining rate of vapor flux between thermocouple and leaf is free of error caused by leaf resistance. The method can be used to measure leaf resistance directly and gives more accurate measurements of water potential than do other methods.

Bradford, M.A., B. W. Watts, C. A. Davies. 2010. Thermal adaptation of heterotrophic soil respiration in laboratory microcosms. Global Change Biology, 16: 1576-1588.

Abstract
Respiration of heterotrophic microorganisms decomposing soil organic carbon releases carbon dioxide from soils to the atmosphere. In the short term, soil microbial respiration is strongly dependent on temperature. In the long term, the response of heterotrophic soil respiration to temperature is uncertain. However, following established evolutionary tradeoffs, mass-specific respiration (Rmass) rates of heterotrophic soil microbes should decrease in response to sustained increases in temperature (and vice-versa). Using a laboratory microcosm approach, we tested the potential for the Rmass of the microbial biomass in six different soils to adapt to three, experimentally imposed, thermal regimes (constant 10, 20 or 30 °C). To determine Rmass rates of the heterotrophic soil microbial biomass across the temperature range of the imposed thermal regimes, we periodically assayed soil subsamples using similar approaches to those used in plant, animal and microbial thermal adaptation studies. As would be expected given trade-offs between maximum catalytic rates and the stability of the binding structure of enzymes, after 77 days of incubation Rmass rates across the range of assay temperatures were greatest for the 10 °C experimentally incubated soils and lowest for the 30 1C soils, with the 20 °C incubated soils intermediate. The relative magnitude of the difference in Rmass rates between the different incubation temperature treatments was unaffected by assay temperature, suggesting that maximum activities and not Q10 were the characteristics involved in thermal adaptation. The time taken for changes in Rmass to manifest (77 days) suggests they likely resulted from population or species shifts during the experimental incubations; we discuss alternate mechanistic explanations for those results we observed. A future research priority is to evaluate the role that thermal adaptation plays in regulating heterotrophic respiration rates from field soils in response to changing temperature, whether seasonally or through climate change.

Bradford, M.A., DeVore, J.L., Maerz, J.C., McHugh, J.V., Smith, C.L., Strickland, M.S. 2009. Native, insect herbivore communities derive a significant proportion of their carbon from a widespread invader of forest understories. Biol Invasions.

Abstract
Research on natural enemies demonstrates the potential for exotic plants to be integrated into foodwebs through the activities of native herbivores. The quantitative importance of exotics as a food resource to herbivores is more difficult to ascertain. In addition, some widespread invaders appear to have minimal herbivore loads. Microstegium vimineum is one example. It is an annual, C4 grass that invades forest understories and is widespread across the eastern US. Its invasion alters the structure and composition of forests. We sampled invertebrates in a tree-canopy gap and under canopy area, and used the unique carbon isotope value of M. vimineum to estimate the quantitative importance of the invader as a food resource relative to native plants. Seven of the eight invertebrate species derived on average [35% of their biomass carbon from M. vimineum, and some individuals representing both ‘chewing’ and ‘sucking’ feeding guilds derived their biomass carbon exclusively from M. vimineum. Our results show that M. vimineum can be a significant food resource for a multi-species, multi-guild, assemblage of native, invertebrate herbivores. Future work is required to assess whether M. vimineum is acquiring herbivores in other parts of its introduced range, and if so what might be the ecological consequences.

Bradford, M.A., et al. 2009. Decreased mass specific respiration under experimental warming is robust to the microbial biomass method employed. Ecology Letters, 12: E15-E18.

Abstract
Hartley et al. question whether reduction in Rmass, under experimental warming, arises because of the biomass method. We show the method they treat as independent yields the same result. We describe why the substrate-depletion hypothesis may not solely explain observed responses, and urge caution in interpretation of the seasonal data.

Bradford, M.A., Strickland, M.S., Devore, J.L., Maerz, J.C. (2012) Root carbon flow from an invasive plant to belowground foodwebs. Plant and Soil. DOI: 10.1007/s11104-012-1210-y

Abstract
Aims Soil foodwebs are based on plant production. This production enters belowground foodwebs via numerous pathways, with root pathways likely dominating supply. Indeed, root exudation may fuel 30–50 % of belowground activity with photosynthate fixed only hours earlier. Yet we have limited knowledge of root fluxes of recent-photosynthate from invasive plants to belowground foodwebs. Methods Using stable isotopes, we quantify the proportion of recent-photosynthate transferred belowground from the invasive grass Microstegium vimineum A. Camus, a widespread invader of forest understory. Given its minimal root biomass (~8 % of individual mass), we expected exudation to contribute little to belowground foodwebs. Results Within 2 days of 13C-labeling, we recover ~15 % of photosynthate carbon in microbial biomass. Recovery in root and dissolved organic carbon pools is consistently low (<2 %), suggesting these pools operate as ‘pipelines’ for carbon transport to soil microbes. The recovery of the label in wolf spiders –forest floor predators that feed on soil animals – highlights that root inputs of recent photosynthate can propagate rapidly through belowground foodwebs. Conclusions Our results suggest that root carbonexudation,an unexplored process of invasive grass inputs to forest foodwebs, may be an important pathway through which invasive species affect the structure and function of recipient ecosystems.

Bradford, M.A., T. Gancos, and C.J. Frost. 2008. Slow-cycle effects of foliear herbivory alter the nitrogen acquistion and population size of Collembola. Soil Biology and Biochemistry 40: 1253-1258

Abstract
In terrestrial systems there is a close relationship between litter quality and the activity and abundance of decomposers. Therefore, the potential exists for aboveground, herbivore-induced changes in foliar chemistry to affect soil decomposer fauna. These herbivore-induced changes in chemistry may persist across growing seasons. While the impacts of such slow-cycle, ‘legacy’ effects of foliar herbivory have some support aboveground, such impacts have not been evaluated for soil invertebrates. Here, we investigate legacy effects on Collembola population structure and nitrogen acquisition. We collected foliar material (greenfall) from trees that had, in the preceding season, been exposed to insect herbivory by leaf-chewing Lepidoptera.

Bradford, Mark A., Ashley D. Keiser, Christian A. Davies, Calley A. Mersmann and Michael S. Strickland. 2013. Empirical evidence that soil carbon formation from plant inputs is positively related to microbial growth. Biogeochemistry 113: 271-281.

Abstract
Plant-carbon inputs to soils in the form of dissolved sugars, organic acids and amino acids fuel much of heterotrophic microbial activity belowground. Initial residence times of these compounds in the soil solution are on the order of hours, with microbial uptake a primary removal mechanism. Through microbial biosynthesis, the dissolved compounds become dominant precursors for formation of stable soil organic carbon. How the chemical class (e.g. sugar) of a dissolved compound influences stabilization in field soils is unknown and predictions from our understanding of microbial metabolism, turnover and identity are contradictory. We show that soil carbon formation, from chronic amendments of dissolved compounds to fertilized and unfertilized grasslands, is 2.4-times greater from a sugar than an amino acid. Formation rates are negatively correlated with respiration rates of the compounds, and positively correlated with their recovery in microbial biomass. These relationships suggest that the efficiency of microbial growth on a compound is positively related to formation rates of soil organic carbon. Fertilization does not alter these findings, but together nitrogen and phosphorus additions reduce soil carbon formation. Our results highlight the need to consider both nutrient enrichment and global-change induced shifts in the form of dissolved root inputs to soils to predict future soil carbon stocks and hence phenomena such as climate warming and food security to which these stock sizes are intimately tied.

Bradford, Mark A., Robert J.Warren II, Petr Baldrian, Thomas W. Crowther, Daniel S. Maynard, Emily E. Oldfield,William R.Wieder, Stephen A.Wood and Joshua R. King, 2014. Climate Fails to Predict Wood Decomposition at Regional Scales. In Nature Climate Change, Letters, advanced online publication at www.nature.com/natureclimatechange

Abstract
Decomposition of organic matter strongly influences ecosystem carbon storage. In Earth-system models, climate is a predominant control on the decomposition rates of organic matter. This assumption is based on the mean response of decomposition to climate, yet there is a growing appreciation in other areas of global change science that projections based on mean responses can be irrelevant and misleading. We test whether climate controls on the decomposition rate of dead wood—a carbon stock estimated to represent 73 _ 6 Pg carbon globally—are sensitive to the spatial scale from which they are inferred. We show that the common assumption that climate is a predominant control on decomposition is supported only when local-scale variation is aggregated into mean values. Disaggregated data instead reveal that local-scale factors explain 73% of the variation in wood decomposition, and climate only 28%. Further, the temperature sensitivity of decomposition estimated from local versus mean analyses is 1.3-times greater. Fundamental issues with mean correlations were highlighted decades ago, yet mean climate–decomposition relationships are used to generate simulations that inform management and adaptation under environmental change. Our results suggest that to predict accurately how decomposition will respond to climate change, models must account for local-scale factors that control regional dynamics.

Brannan, J.R., J.A. Reneke, and J. Waide. 1984. A diffusion model of forest succession. Mathematical Biosciences 69: 131-149.

Abstract
Based on a tree by tree replacement mechanism, a diffusion model of forest stand canopy composition is formulated and analyzed. The model is used to explore composition dichotomies by estimating coefficients from forest stand data and interpreting the results in terms of mechanisms for succession. The model yields a concrete characterization of the succession phenomenon known as the climax state.

Brantley, S. T., Miniat, C. F., Elliott, K. J., Laseter, S. H. and Vose, J. M. (2014), Changes to southern Appalachian water yield and stormflow after loss of a foundation species. Ecohydrology. Doi: 10.1002/eco.1521

Abstract
Few studies have examined how insect outbreaks affect landscape-level hydrologic processes.We report the hydrologic effects of the invasive, exotic hemlock woolly adelgid (HWA) in a headwater catchment in the southern Appalachian Mountains. The study watershed experienced complete mortality of an evergreen tree species, Tsuga canadensis (L.) Carr. (eastern hemlock), after infestation was first detected in 2003. Hemlock mortality resulted in a ~6% reduction in basal area in the watershed, and this loss was primarily concentrated in riparian zones.We used a paired-watershed approach to quantify changes inwater yield and peak stormflow using streamflow data from the infested watershed and a nearby watershed with significantly lower hemlock basal area. We hypothesized that yieldwould increase shortly after hemlock infestation but decrease over the longer-term. Wefound that annual yield did not increase significantly in any year after infestation but decreased significantly by 12·0cm (~8%) in 2010. Monthly yield also decreased after infestation, but changes were limited to the dormant season. The decline in yield is likely to persist as hemlock is replaced by specieswith higher transpiration rates. Peakflow increased significantly after infestation during the two largest flow events in the post-infestation period. Changes in stormflow during extreme events may have been temporary as another evergreen, Rhododendron maximum, may have mitigated some of the changes after hemlock loss. Thus, streams draining watersheds where eastern hemlock has been lost due to HWA infestation demonstrate permanent reductions in yield and transient increases in peakflow during large-flow events. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Brantley, S.T., Miniat, C.F. and Vose, J.M. 2013. Future species composition will affect forest water use after loss of eastern hemlock from southern Appalachian forests. Ecological Applications. 23(4):777-790. (DOI: http://dx.doi.org/10.1890/12-0616.1)

Abstract
Infestation of eastern hemlock (Tsuga canadensis (L.) Carr.) with hemlock woolly adelgid (HWA, Adelges tsugae) has caused widespread mortality of this key canopy species throughout much of the southern Appalachian Mountains in the past decade. Because eastern hemlock is heavily concentrated in riparian habitats, maintains a dense canopy, and has an evergreen leaf habit, its loss is expected to have a major impact on forest processes, including transpiration (Et). Our goal was to estimate changes in stand-level Et since HWA infestation, and predict future effects of forest regeneration on forest Et in declining eastern hemlock stands where hemlock represented 50�“60% of forest basal area. We used a combination of community surveys, sap flux measurements, and empirical models relating sap flux-scaled leaf-level transpiration (EL) to climate to estimate the change in Et after hemlock mortality and forecast how forest Et will change in the future in response to eastern hemlock loss.From 2004 to 2011, eastern hemlock mortality reduced annual forest Et by 22% and reduced winter Et by 74%. As hemlock mortality increased, growth of deciduous tree species�”especially sweet birch (Betula lenta L.), red maple (Acer rubrum L.), yellow poplar (Liriodendron tulipifera L.), and the evergreen understory shrub rosebay rhododendron (Rhododendron maximum L.)�” also increased, and these species will probably dominate post-hemlock riparian forests. All of these species have higher daytime EL rates than hemlock, and replacement of hemlock with species that have less conservative transpiration rates will result in rapid recovery of annual stand Et. Further, we predict that annual stand Et will eventually surpass Et levels observed before hemlock was infested with HWA. This long-term increase in forest Et may eventually reduce stream discharge, especially during the growing season. However, the dominance of deciduous species in the canopy will result in a permanent reduction in winter Et and possible increase in winter stream discharge. The effects of hemlock die-off and replacement with deciduous species will have a significant impact on the hydrologic flux of forest transpiration, especially in winter. These results highlight the impact that invasive species can have on landscape-level ecosystem fluxes.

Brantley, Steven T., Mayfield, Albert (Bud), Jetton, Robert M., Miniat, Chelcy F., Zietlow, David R.;, Brown, Cindi L., Rhea, Rusty (2017), Elevated light levels reduce hemlock woolly adelgid infestation and improve carbon balance of infested eastern hemlock seedlings, Forest Ecology and Management, 386:150-160, http://dx.doi.org/10.1016/j.foreco.2016.11.028

Abstract
The rapid loss of eastern hemlock (Tsuga canadensis) due to infestation with hemlock woolly adelgid (Adelges tsugae, HWA) has greatly altered structure and function of eastern forests. Numerous control strategies including local pesticide use and biocontrol with predator beetles have been implemented with considerable cost and varying success. Silviculture treatments that increase incident light on surviving hemlock trees to reduce infestation and ameliorate carbon starvation have been proposed as another possible conservation strategy, yet no controlled studies have evaluated the coupled plant-insect responses to increased light. We conducted a nursery experiment on artificially infested eastern hemlock seedlings under varying levels of ambient light, ranging from 0 to 90% shade. We measured HWA infestation (ovisac density), short- and long-term indicators of carbon balance (leaf chlorophyll fluorescence, net photosynthesis, total nonstructural carbohydrate content, and shoot growth), and nutrition (leaf N content). We hypothesized that higher light would result in reduced HWA densities, higher C assimilation rates, and improved tissue non-structural carbohydrate balance; and these effects would ameliorate the effects of infestation on C balance and lead to improved seedling growth. HWA density decreased with increasing light, and was highest in the 90% shade treatments. However, photosystem II efficiency and net assimilation were also lower under the higher light treatment. Despite tradeoffs between reduced infestation and reduced leaf function from higher light, and little variation in sugar content among treatments, both leaf and root starch content and seedling growth were higher under the higher light treatment. Increasing light levels improves long-term carbon balance for hemlock seedlings in the presence of HWA. Although hemlock typically occurs in deeply shaded forests, our results suggest that silvicultural treatments such as forest thinning that increase light exposure may reduce HWA abundance and lead to better tree C balance, and may be an effective component of large-scale conservation and restoration strategies.

Brantley, Steven T., Morgan L. Schulte, Paul V. Bolstad, and Chelcy F. Miniat. 2016. Equations for Estimating Biomass, Foliage Area, and Sapwood of Small Trees in the Southern Appalachians. Forest Science. 62(4)414-421. http://dx.doi.org/10.5849/forsci.15-041.

Abstract
Small trees and shrubs play an important role in forest diversity and regeneration and may contribute substantially to ecosystem fluxes of carbon and water; however, relatively little attention is given to quantifying the contribution of small trees to forest processes. One reason for this may be that the allometric equations developed for large trees tend to systematically underestimate structural variables such as biomass and foliage area when applied to small trees, both on an individual tree level and at the stand level. To test this hypothesis, we developed allometric equations for trees 10 cm dbh (D) for seven dependent variables (woody, foliage, and total biomass; woody, foliage, and whole-plant surface area; and sapwood area) and compared these new equations with the existing equations for large trees. We found significant differences between small tree and large tree equations for most variables and showed that equations for large trees tend to underestimate the structural characteristics of small trees. When we applied new size-specific equations to forest survey data representing a chronosequence of forest development, estimates of small tree biomass increased 30–73% and estimates of foliage area increased 72–142% compared with results using only equations for large trees. These results suggest that small trees can contribute substantially to forest structure and associated ecosystem fluxes, especially in stands with a large proportion of small trees. However, size-specific equations for small trees did not substantially change the estimates of forest biomass in these stands, and the need to develop size-specific equations may depend on the variables of interest.

Brian J. Burke, Meredith Welch-Devine, Seth Gustafson, Nik Heynen, Jennifer L. Rice, Ted L. Gragson, Sakura R. Evans & Donald R. Nelson (2015): Can Science Writing Collectives Overcome Barriers to More Democratic Communication and Collaboration? Lessons from Environmental Communication Praxis in Southern Appalachia, Environmental Communication, DOI: 10.1080/17524032.2014.999695

Abstract
Despite compelling reasons to involve nonscientists in the production of ecological knowledge, cultural and institutional factors often dis-incentivize engagement between scientists and nonscientists. This paper details our efforts to develop a biweekly newspaper column to increase communication between ecological scientists, social scientists, and the communities within which they work. Addressing communitygenerated topics and written by a collective of social and natural scientists, the column is meant to foster public dialog about socio-environmental issues and to lay the groundwork for the coproduction of environmental knowledge. Our collective approach to writing addresses some major barriers to public engagement by scientists, but the need to insert ourselves as intermediaries limits these gains. Overall, our efforts at environmental communication praxis have not generated significant public debate, but they have supported future coproduction by making scientists a more visible presence in the community and providing easy pathways for them to begin engaging the public. Finally, this research highlights an underappreciated barrier to public engagement: scientists are not merely disconnected from the public, but also connected in ways that may be functional for their research. Many field scientists, for example, seek out neutral and narrowly defined connections that permit research access but are largely incompatible with efforts to address controversial issues of environmental governance.

Britton, K., W. Pepper, D. Loftis, and D. Chellemi. 1994. Effect of timber harvest practices on populations of Cornus florida and severity of dogwood anthracnose in western North Carolina. Plant Disease 78(4): 398-402.

Abstract
Stand composition and severity of dogwood anthracnose, caused by Discula destructiva, were measured on 39 plots located at the Coweeta Hydrologic Laboratory in western North Carolina. The 0.08-ha plots were selected along transects across watersheds previously clearcut, partially harvested, or not harvested. Basal diameter, percent leaf area with dogwood anthracnose symptoms, and percent branch dieback were estimated for Cornus florida. Dogwood anthracnose was most severe on partially harvested watersheds and least severe on the clearcut watershed. Density of C. florida was greatest on the clearcut watershed, and the number of dogwood stems was inversely correlated (r=-0.31, P=0.05) with disease severity. Dogwood basal area, species importance value, and stand basal area were not significantly affected by harvest treatment and were not correlated with disease severity. In a second study, anthracnose severity was rated in 21 plots of yellow poplar near Asheville, North Carolina, that had been thinned to varying densities in the early 1960s. Among these 0.1-ha plots, thinning intensity did not affect disease severity. Disease severity was inversely related to dogwood size.

Britton, K.O. 1993. Anthracnose infection of Dogwood seedlings exposed to natural inoculum in western North Carolina. Plant Disease. 77(1): 34-37.

Abstract
Groups of 25 healthy dogwood seedlings were exposed for 2 wk to naturally occurring inoculum under mature, diseased trees at 2-wk intervals for three growing seasons. After exposure, seedlings were placed in an incubation room and supplied with trickle irrigation and fluorescent lighting for 2 wk. Following incubation, percent leaf area infected (LAI) was estimated visually. In 1989, LAI remained less than 5% until June. However, consistent rainfall throughout the summer created conditions conducive to infection of seedling groups exposed from 6 June through September, and LAI ranged from 11 to 47% during that period. In 1990 and 1991, LAI was less than 5% until early May, and heavy infection began in mid-May. Midsummer droughts reduced LAI to less than 5%. LAI increased with renewed rainfall but dropped below 10% for the remainder of the season beginning in mid-July 1990 and in September 1991. Numerous secondary infection cycles occurred in each of the 3 yr. Stepwise regression analysis showed that 34% of the variance in LAI was explained by 2-wk rainfall total and 17% was explained by the LAI of the previous seedling group. This supports the hypothesis that secondary infection cycles in southwestern North Carolina depend on consistently recurring rainfall and inoculum buildup.

Brockman, E.R., and R.L. Todd. 1974. Fruiting myxobacters as viewed with a scanning electron microscope. International Journal of Systematic Bacteriology 24: 118-124.

Abstract
Unfixed fruiting bodies of myxobacters have been viewed in great detail with a scanning electron microscope. Specimens of species of the genera Myxococcus, Chondrococcus, Archangium, Stelangium, Melittangium, Cystobacter, Polyangium, Stigmatella, and Chondromyes were examined. The desirability of using the scanning electron microscope for the study of the gross morphology of myxobacter structures has been clearly demonstrated.

Brookshire, E.N.J., H.M. Valett, S.A. Thomas, and J.R. Webster. 2005. Coupled cycling of dissolved organic nitrogen and carbon in forest streams. Ecology 86(9): 2487-2496.

Abstract
Dissolved organic nitrogen (DON) is an abundant but poorly understood pool of N in many ecosystems. We assessed DON cycling in a N-limited headwater forest stream via whole-ecosystem additions of dissolved inorganic nitrogen (DIN) and labile dissolved organic matter (DOM), hydrologic transport and biogeochemical modeling, and laboratory experiments with native sediments. We sampled surface and subsurface waters to understand how interaction among hydrologic exchange, DIN, DON, and dissolved organic carbon (DOC) influence stream N losses at summer baseflow. Added DON was taken up rapidly from the water column at rates exceeding DOC and DIN. A significant fraction of this DON was mineralized and nitrified. Combined DON and NO3-N uptake lengths resulted in spiraling lengths of ;210 m, suggesting the potential for multiple transformations of labile N loads within catchment boundaries. Simultaneous addition of DIN increased DOM uptake, but more so for C, resulting in an upward shift in the C:N ratio of uptake. Sediment incubations also showed a strong biotic influence on DOC and DON dynamics. Despite efficient uptake of added DOM, background DON and high molecular mass DOC concentrations increased downstream, resulting in higher DOM loads than could be accounted for by groundwater discharge and suggesting net release of less bioavailable forms from the channel/hyporheic zone. At the same time, subsurface DOM was characterized by very low C:N ratios and a disproportionately large DON pool despite rapid hydrologic mixing with dilute and high C:N ratio surface waters. Analysis of expected DON loads from conservative hyporheic fluxes indicated that watershed losses of DON would have been seven times greater in the absence of apparent benthic demand, suggesting tight internal cycling of subsurface DON. Our study further demonstrates the potential for significant transformation of N in headwater streams before export to downstream ecosystems.

Brookshire, J., S. Gerber, J.R. Webster, J.M. Vose, and W.T. Swank. Direct effects of temperature on forest nitrogen cycling revealed through analysis of long term watershed records. Global Change Biology

Abstract
The microbial conversion of organic nitrogen (N) to plant available forms is a critical determinant of plant growth and carbon sequestration in forests worldwide. In temperate zones, microbial activity is coupled to variations in temperature, yet at the ecosystem level, microbial N mineralization seems to play a minor role in determining patterns of N loss. Rather, N losses often appear to vary with seasonality in hydrology and plant demand, while exports over longer periods are thought to be associated with increasing rates of anthropogenic N deposition. We analyzed long-term (21–32 years) time series of climate and stream and atmospheric chemistry from two temperate deciduous forest watersheds in the southeastern USA to understand the sensitivity of internal forest N cycles to climate variation and atmospheric deposition. We evaluated the time series with a simple analytical model that incorporates key biotic constraints and mechanisms of N limitation and cycling in plant–soil systems. Through maximum likelihood analysis, we derive biologically realistic estimates of N mineralization and its temperature sensitivity (Q10).We find that seasonality and long-term trends in stream nitrate (NO3) concentrations can in large part be explained by the dynamics of internal biological cycling responding to climate rather than external forcing from atmospheric chemistry. In particular, our model analysis suggests that much of the variation in N cycling in these forests results from the response of microbial activity to temperature, causing NO3 losses to peak in the growing season and to accelerate with recent warming. Extrapolation of current trends in temperature and N deposition suggests that the upturn in temperature may increase future N export by greater than threefold more than from increasing deposition, revealing a potential direct effect of anthropogenic warming on terrestrial N cycles.

Brookshite, E.N.J, Valett, H.M., Gerber, S. 2009. Maintenance of terrestrial nutrient loss signatures during in-stream transport. The Ecological Society of America, 90(2): 293-299

Abstract
Small streams account for the majority of channel length in river basins worldwide and are the primary conveyors of terrestrial nutrients to rivers and ultimately the oceans. The controls of stream nutrient fluxes, however, are debated. Classical models emphasize that nutrient transport in streams integrates nutrient cycling in the terrestrial watershed while others argue that in-stream processes control nutrient flux. Recent studies have shown that in-stream cycling can be important in determining downstream nutrient fluxes, but results have not been reconciled with mass–balance calculations at the small watershed scale. Here we use a simple analytical framework to assess nutrient cycling in streams and show that, under most conditions, longitudinally static nutrient concentrations reflect in-stream biotic balance between uptake and regeneration and groundwater inputs. Using measures of nutrient concentrations in small streams across four biomes, we provide evidence for generality of biogeochemical steady state (inputs¼outputs) in stream ecosystems: overall, longitudinal profiles were flat for nitrogen and phosphorus and were similar in concentration to soil and ground waters. Deviation from flat longitudinal profiles was associated with seasonal or successional biomass growth and small groundwater inputs relative to in-stream sink strength. We conclude that streams tend strongly toward nutrient balance, allowing use of their chemistry as an integrated measure of terrestrial nutrient losses.

Bruce, R. 2011. COMMUNITY ASSEMBLY IN THE SALAMANDER GENUS DESMOGNATHUS. Herpetological Monographs, 25, 1-24. Retrieved from http://www.jstor.org/stable/41406828

Abstract
Abstract: In this paper, I present a model of community assembly in the salamander Desmognathus based on a survey of assemblage composition throughout the range of the genus. species of Desmognathus can be sorted into three life-history categories, namely, stream, streamside, forest, based on duration of the larval phase and a suite of other life-history and morphological traits correlated with habitat use of the several life-history stages. In most assemblages having all three life-categories, stream species are larger than streamside species, and the latter species are larger than species. An evaluation of the literature on interspecific competition and prédation (i.e., intraguild in Desmognathus indicates that these processes are important in structuring assemblages salamanders. Thus, niche assembly, as opposed to dispersal assembly (i.e., neutral model), seems to model of community assembly in Desmognathus. Only streamside species occur throughout the range genus, and these forms alone are found around the periphery of the range. One to three streamside form the base of extant assemblages of Desmognathus , with stream and forest species contributing more diverse assemblages of the southern Appalachian region. The maximum numbers are two streamside species, two or three stream species, and two forest species, although assemblages of more six species are undocumented. I suggest that the rapid evolutionary diversification in body size and life in Desmognathus that has generated the complex assemblages of this genus in the Appalachians has facilitated by a high level of life-history symmetry in these

Bruce, R. C. 2010. Proximate contributions to adult body size in two species of dusky salamanders (Plethodontidae: Desmognathus). Herpetologica, 66(4): 393-402.

Abstract
I used skeletochronological data to evaluate the contributions of propagule size, larval/juvenile growth, and age at first reproduction to differences in adult body size in two species of plethodontid salamanders of the genus Desmognathus. The traits in question were evaluated in populations of the larger D. quadramaculatus and smaller D. monticola in the southern Blue Ridge Mountains of North Carolina, USA. Gompertz and von Bertalanffy functions were fitted to the plots of standard length on skeletochronological age of each complete sample (larvae and/or juveniles, and adults) of earlier data sets; linear functions were fitted to data of immatures (larvae and/or juveniles). In order to examine the relationship of body mass and age, I conducted regressions of body mass on standard length in later samples of both species, calculated estimated body masses of the salamanders in the skeletochronological data sets, and then fitted a modified Gompertz function to each plot of body mass on age. The results showed that age at first reproduction is the principal factor contributing to differences between the species in size at first reproduction and adult size. Larger propagule sizes (i.e., hatching sizes) in D. quadramaculatus versus D. monticola may also be a factor; however, there is no evidence that a difference in larval/juvenile growth rate contributes to the adult size differential. Comparison of two populations of D. monticola suggested that small differences in adult body size result mainly from slight differences in age at first reproduction. Tradeoffs among propagule size, clutch size, growth, and age and size at first reproduction are discussed in the context of selective pressures that may have generated diversification in body size and life history in the genus.

Bruce, R.C. 1988. Life history variation in the salamander Desmognathus quadramaculatus. Herpetologica 44(2): 218-227.

Abstract
Age at metamorphosis and age at first reproduction were studied in three populations of Desmognathus quadramaculatus in the southern Blue Ridge Mountains of southwestern North Carolina. Four age classes of larvae were identified in all three populations through the analysis of size distributions. The frequency of early metamorphosis at 3 yr. or even 2 yr. varied considerably among the populations. This variation was reflected in the size distributions of both larvae and post-metamorphic juveniles. The minimum age at first reproduction was estimated to be 6 yr. in males and 7 yr. in females in all three populations. Age at metamorphosis and age at first reproduction probably vary independently in D. quadramaculatus. It appears that interspecific variation in adult body size in the genus Desmognathus is correlated positively with age at first reproduction and may not reflect variation in growth rates.

Bruce, R.C. 2013. Size-Mediated Tradeoffs in Life-History Traits in Dusky Salamanders. Copeia. (DOI: 10.1643/CE-12-120)

Abstract
Among salamanders of the genus Desmognathus, the larger species tend to be more aquatic and the smaller more terrestrial. I studied life histories in assemblages of Desmognathus in the southern Blue Ridge Mountains of North Carolina at sites in the Cowee and southern Nantahala Mountains. Traits evaluated included mortality/survival, age at first reproduction, fecundity, and body size. The first three are direct fitness traits that enter into the characteristic equation, x=aS�lxmxe2rx = 1.0. One assemblage (Wolf Creek), in the Cowee Mountains, comprises three species, from larger to smaller, D. quadramaculatus, D. monticola, and D. ocoee. A second assemblage (Coweeta Creek), in the Nantahala Mountains, also includes D. quadramaculatus, D. monticola, and D. ocoee, as well as the smaller D. aeneus and D. wrighti. I also studied three species only (D. ocoee, D. aeneus, D. wrighti) in an assemblage of six species (Nantahala River) in the Nantahala Mountains just west of Coweeta Creek. In these assemblages, age at first reproduction and fecundity are greater in the larger, more aquatic species. Instantaneous mortality rate is lower in the larger species; however, the latter have lower survival to first reproduction than the smaller species because developmental time to sexual maturation is lengthier than in the smaller species. Among species, it appears that size-mediated tradeoffs exist among age at sexual maturation, fecundity, and survival. The tradeoff relationships of life-history traits among species in both the Cowee and Nantahala assemblages may reflect fitness invariance or symmetry, perhaps stemming from design constraints in the genus Desmognathus. What remain unclear are factors contributing to the correlation between body size and the position of species along the stream-to-forest habitat gradient.

Bruce, R.C., and N.G. Hairston Sr. 1990. Life-history correlates ofbody-size differences between two populations of the salamander, Desmognathusmonticola. Journal of Herpetology 24(2): 124-134.

Abstract
Samples were compared of Desmognathus monticola taken independently at two nearby localities in southwestern North Carolina. Larger adult body sizes are attained by both sexes at Coweeta Hydrologic Laboratory in the Nantahala Mountains than at Wolf Creek in the Coweeta Mountains. The juvenile period appears to be longer in the former population, resulting in larger sizes at maturation in both males and females. The proportion of older males is greater at Coweeta than at Wolf Creek, suggesting higher male survival in the former population. Clutch sizes are lower at Coweeta than at Wolf Creek, even though Coweeta females are larger. This suggests that the population differences in body size may represent differences in age at maturation rather than differences in growth rates. The pattern of variation in life history parameters suggests that extrinsic survival probabilities differ between the sites, with Coweeta representing a safer environment for D. monticola than Wolf Creek.

Bruce, R.C., J. Castanet, and H. Francillon-Viellot. 2002. Skeletochronological analysis of variation in age structure, body size, and life history in three species of desmognathine salamanders. Herpetologica. 58(2): 181-193.

Abstract
We evaluated age structure in three species of desmognathine salamanders at Coweeta Hydrologic Laboratory, North Carolina, for comparison with the results of an earlier study of age structure in these species at a nearby locality (Wolf Creek, North Carolina). At Coweeta, both Desmognathus quadramaculatus and D. monticola attain larger adult body sizes and greater ages than their Wolf Creek counterparts. The differences appear to stem in part from greater ages at sexual maturation in both species at Coweeta versus Wolf Creek. This disparity is most pronounced in D. quadramaculatus, where the estimated ages at first reproduction are 7-8 yr. in males and 9-10 yr. in females. The Coweeta populations of D. quadramaculatus and D. monticola may also have higher survivorship and higher rates of post-maturational growth than those at Wolf Creek. In contrast, in the third and smallest species, D. ocoee, the Coweeta population did not differ in size and age attributes from that at Wolf Creek. We hypothesize that the more mesic climate of Coweeta versus Wolf Creek is a safer environment for the two larger, aquatic to semi-aquatic desmognathines, eliciting selection for later maturation and thus larger body sizes. In contrast, selection on the life history of the smaller and more terrestrial D. ocoee at both localities may derive mainly from factors other than the climatic differential.

Bruce, R.C.. 1996. Life-history perspective of adaptive radiation in desmognathine salamanders. Copeia. 1996. 4: 783-790.

Abstract
This study investigates interspecific variation in age at first reproduction, fecundity, and body size in multispecies assemblages of desmognathine salamanders. The hypotheses tested are that inter- specific differences in body size among desmognathines stem proximately from variation in age at first reproduction and that variation in the latter trait is positively correlated with variation in fecundity among species. It is shown that a correlation between age at first reproduction and fecundity, combined with a uniform rate of survival, based on available estimates of these parameters, will yield equivalent values of net reproductive rate among the species of a given assemblage. Such equivalence represents a form of life-history symmetry. Data from two assemblages are presented in support of the argument for symmetry. Such life-history symmetry may reflect uniformity in morphological specialization in desmognathines. Given the morphological adaptations to burrowing in the subfamily, the relationship between adult body size and habitat preference in Desmognathus may reflect adaptation to the size of cover objects and composition of the substratum along the aquatic-terrestrial habitat gradient. I propose that these variables, in association with predation and competition, represent the selective factors responsible for body size diversification in Desmognathus.

Bruce, Richard C. 2016. Application of the Gompertz Function in Studies of Growth in Dusky Salamanders (Plethodontidae: Desmognathus). Copeia. 104(1):94-100. DOI: 10.1643/CE-14-204.

Abstract
Gompertz growth functions were fitted to skeletochronological data sets of three species of desmognathine salamanders from an assemblage (Wolf Creek) in the Cowee Mountains of southwestern North Carolina. The results were compared to earlier evaluations of growth in desmognathines from a nearby assemblage (Coweeta) in the Nantahala Mountains. In two of the species, Desmognathus quadramaculatus and D. monticola, larger adult body sizes were attained at Coweeta than at Wolf Creek, whereas adult body sizes of the third species, D. ocoee, were similar in the two populations. Growth in both standard length (snout–vent length) and body mass were evaluated. The early phases of growth, prior to sexual maturation, were similar in the larger D. quadramaculatus and the smaller D. monticola, and higher in both species than in the even smaller D. ocoee. In all three species, growth rates tended to be higher in the Coweeta populations than in those at Wolf Creek. The inflexions of the Gompertz curves for body mass versus age, representing the maximum rates of growth, occurred at or near the age of first reproduction, which is expected, given the tendency for growth to slow at sexual maturation in desmognathines and other salamanders. The results support earlier findings that differences in adult body size between D. quadramaculatus and D. monticola are mainly effects of differences in age at sexual maturation, modulated by a difference in propagule size, as opposed to growth differences. However, the difference in adult size between these species and D. ocoee are joint effects of smaller propagule size, lower growth rate, and earlier maturation in the latter species.

Bryan Currinder, Kristen K. Cecala, Robert M. Northington & Michael E. Dorcas (2014) Response of stream salamanders to experimental drought in the southern Appalachian Mountains, USA, Journal of Freshwater Ecology, 29:4, 579-587, DOI: 10.1080/02705060.2014.938135

Abstract
Droughts act as significant disturbances to freshwater animals and their ecosystems. Given the impending threat of more frequent and persistent droughts because of global climate change, the lack of data on the responses of many aquatic animals to drought is a cause for concern. This study examined the body condition of the most commonly detected species (Desmognathus quadramaculatus) and abundance of commonly found species after two years of experimental drought in two first-order streams in the southern Appalachian Mountains. Our results indicated negative effectsof drought on the stream salamander community. The body condition of D. quadramaculatus larvae in experimental drought transects was significantly lower than larvae captured in control reaches, which may have resulted from lower macroinvertebrate production in experimental reaches. Additionally, larval D. quadramaculatus abundance declined 47% in experimental drought transects, and Eurycea wilderae larvae and D. ocoee adults were 70% less likely to be captured in experimental stream transects. Our findings contribute additional evidence that stream plethodontids have little resistance to drought. With extended droughts resulting from climate change more likely in the future, more research is necessary to determine if reduced body condition, production, and lowered abundance have effects on longterm population viability.

Bumpers PM, Rosemond AD, Maerz JC, Benstead JP. 2017. Experimental nutrient enrichment of forest streams increases energy flow to predators along greener food-web pathways. Freshw Biol. 2017;62:1794–1805. https://doi.org/10.1111/fwb.12992

Abstract
Nutrient enrichment is a key stressor of lakes and streams globally, affecting the relative availability of important basal resources such as algae and detritus. These effects are controlled by responses of autotrophic and heterotrophic microorganisms that subsequently affect primary consumers and higher level predators. Despite the potential for propagation of these bottom-up effects, few studies have examined how nutrients affect “green” (autotrophic) versus “brown” (heterotrophic) energy pathways to predators via changes in the quantity or type of prey consumed. We studied the pathways by which nutrient enrichment affected two predatory salamander species (Desmognathus quadramaculatus and Eurycea wilderae) using detailed diet analyses before and during 2-year nutrient additions to five headwater forest streams. The streams were continuously enriched with different concentrations of dissolved nitrogen (N) and phosphorus (P), creating relatively greater N or P concentrations and distinct N:P ratios (2:1, 8:1, 16:1, 32:1 and 128:1) in each stream. Nutrient addition resulted in greater prey number, size and biomass consumed by D. quadramaculatus, an effect driven more by P than by N additions. Some of these effects were greater in the second year of enrichment and were greater for larger individuals. Shifts in the prey composition of D. quadramaculatus included increases in algivores and decreases in detritivores, tracking observed treatment effects on basal resource quantity (e.g. algivore abundance in guts was related to algal biomass, which increased with enrichment, and detritivore abundance in guts was related to detrital standing stocks, which declined with enrichment). For E. wilderae diets, there was limited evidence for increased prey size and number, or for alteration of prey composition with enrichment despite evidence of increased larval growth. We hypothesise that body size differences between the two salamander species partially explain their different dietary responses to enrichment. Our results show that nutrient addition, primarily of P, affected the quantity and composition of predator diets in our nutrient-poor streams. These effects on diet were consistent with concurrent studies showing that P enrichment resulted in faster growth of salamanders and occurred partly via effects on algal biofilm or “green” food-web pathways, despite the dominance of detrital or “brown” resources in our heavily shaded forest stream sites. Thus, nutrient enrichment can promote algae- versus detritus-based energy-flow pathways in nominally light-limited stream ecosystems, with associated changes in food-web characteristics and function.

Burcher, C.L., and E.F. Benfield. 2006. Physical and biological responses of streams to suburbanization of historically agriculture watersheds. Journal of the North American Benthological Society. 25(2): 356-369.

Abstract
We investigated whether suburbanization influenced the physical and biological characteristics of ten 3rd-or 4th-order streams that drain historically agricultural watersheds in the southern Appalachians near Asheville, North Carolina. Five watersheds had areas of recent suburban development proximal to stream sites, and 5 watersheds were not currently undergoing suburban development. We estimated 5 hydrological, 10 geomorphological, 6 erosional, and 3 depositional (i.e., substrate) variables, and 13 fish and 8 macroinvertebrate metrics in the study sites. We used Student¼s t-tests and multivariate analysis of variance to compare the 45 variables between sites in agricultural and suburban watersheds. We used Detrended Correspondence Analysis (DCA) to detect subtle differences in taxonomic composition and abundance among watersheds. Stormflow total suspended solids were significantly lower and substrate inorganic matter content was significantly higher in streams influenced by suburban development. Fish taxa richness and the density of nonguarding fishes were significantly higher in sites in suburban watersheds than in sites in agricultural watersheds. No other fish or macroinvertebrate metric differed with respect to watershed land use, but ordination of sites by fish and macroinvertebrate species abundance suggested that biotic assemblages at sites in suburban watersheds were distinct from those at sites in agricultural watersheds. Therefore, some taxa may have been influenced by suburban development. Our results suggest that watershed hydrology, sediment delivery, and sediment composition might be important factors influencing biota in streams draining agricultural vs suburban watersheds. Biological assemblages in streams differed structurally with respect to watershed land use, but streams did not appear to be otherwise influenced by suburban development. We conclude that suburbanization near historically agricultural southern Appalachian streams induces subtle changes to inorganic sediment dynamics, substrate composition, and fish and macroinvertebrate assemblage structure.

Burcher, C.L., H.M. Valett, and E.F. Benfield. 2007. The land-cover cascade: Relationships coupling land and water. Ecology. 88(1): 228-242.

Abstract
We introduce the land-cover cascade (LCC) as a conceptual framework to quantify the transfer of land-cover-disturbance effects to stream biota. We hypothesize that disturbance is propagated through multivariate systems through key variables that transform a disturbance and pass a reorganized disturbance effect to the next hierarchical level where the process repeats until ultimately affecting biota. We measured 31 hydrologic, geomorphic, erosional, and substrate variables and 26 biotic responses that have been associated with land-use disturbance in third- and fourth-order streams in the Blue Ridge physiographic province in western North Carolina (USA). Regression analyses reduced this set of variables to include only those that responded to land cover and/or affected biota. From this reduced variable set, hypotheses were generated that predicted the disturbance pathways affecting each biotic response following the land-cover-cascade design. Cascade pathways began with land cover and ended with biotic responses, passing through at least one intermediate ecosystem abiotic component. Cascade models were tested for predictive ability and goodness-of-fit using path analysis. Biota were influenced by near-stream urban, agricultural, and forest land cover as propagated by hydrologic (e.g., discharge), geomorphic (e.g., stream bank height), erosional (e.g., suspended sediments), and depositional streambed (e.g., substrate size) features occurring along LCC pathways, reflecting abiotic mechanisms mediating land-cover disturbance. Our results suggest that communities are influenced by land-cover change indirectly through a hierarchy of associated abiotic components that propagate disturbance to biota. More generally, the land-cover cascade concept and experimental framework demonstrate an organized approach to the generic study of cascades and the complex relationships between landscapes and streams.

Burcher, C.L., M.E. McTammany, E.F. Benfield, and G.S. Helfman. 2008. Fish assemblages responses to forest cover.  Environmental Management. 41: 336-346.

Abstract
We investigated whether fish assemblage structure in southern Appalachian streams differed with historical and contemporary forest cover. We compared fish assemblages in 2nd–4th order streams draining watersheds that had increased forest cover between 1950 and 1993 (i.e., reforesting watersheds). We sampled fish in 50 m reaches during August 2001 and calculated catch-per-unit-effort (CPUE) by taxonomic, distributional, trophic, reproductive, and thermal metrics. We assigned streams to reforestation categories based on cluster analysis of years 1950 and 1993 near-stream forest cover. The relationship between forest cover and assemblage structure was assessed using analysis of variance to identify differences in fish CPUE in five forest cover categories.

Burke, B.J. and N. Heynen (2014) Transforming Participatory Science into Socio-Ecological Praxis: Valuing Marginalized Environmental Knowledges in the Face of the Neoliberalization of Nature and Science. Environment and Society. 5: 7-27

Abstract
Citizen science and sustainability science promise the more just and democratic production of environmental knowledge and politics. In this review, we evaluate these participatory traditions within the context of (a) our theorization of how the valuation and devaluation of nature, knowledge, and people help to produce socioecological hierarchies, the uneven distribution of harms and benefi ts, and inequitable engagement within environmental politics, and (b) our analysis of how neoliberalism is reworking science and environmental governance. We fi nd that citizen and sustainability science oft en fall short of their transformative potential because they do not directly confront the production of environmental injustice and political exclusion, including the knowledge hierarchies that shape how the environment is understood and acted upon, by whom, and for what ends. To deepen participatory practice, we propose a heterodox ethicopolitical praxis based in Gramscian, feminist, and postcolonial theory and describe how we have pursued transformative praxis in southern Appalachia through the Coweeta Listening Project.

Burke, B.J., Welch-Devine, M. and Gustafson, S. 2015. Nature Talk in an Appalachian Newspaper: What Environmental Discourse Analysis Reveals about Efforts to Address Exurbanization and Climate Change. Human Organization. 74(2):185-196.

Abstract
As the people of Southern Appalachia confront the challenges of climate change and exurban development, their foundational beliefs about the environment and human-environment relations will significantly shape the types of individual and collective action that they imagine and pursue. In this paper, we use critical discourse analysis of an influential small-town newspaper to understand how the environment is being represented publicly and consider how these representations might affect local environmental politics and efforts to mitigate or adapt to climate change and exurban sprawl. We find that the environment is generally represented as an amenity to be enjoyed rather than a subject of concern, that environmental degradation, when represented at all, is often discussed in vague or distancing terms, and that human agency is typically presented in individualizing, hyper-local terms rather than in collective, community- or national-scale ones. In conclusion, we suggest that these representational styles are likely very effective for inspiring interest in and connection to local landscapes, but they do not provide a strong basis for collective efforts to understand and address climate change and exurbanization

Burnash, R.J.C. 1988. Forest hydrology and ecology at Coweeta, Ecological Studies, Volume 66. Bulletin of the American Meteorological Society 69(11): 1357-1358.

Abstract
A review of the Coweeta Symposium volume.

Burt, T. P. and W. T. Swank. 2010. Classics in physical geography revisited: Hursh CR and Brater EF (1941) Separating storm-hydrographs from small drainage-areas into surface-and subsurface-flow. Transactions, American Geophysical Union 22: 863–871. Progress in Physical Geography, 1-8.

Burt, T., and W. Swank. 2002. Forest or floods? Geography Review. 15(5): 37-41.

Abstract
This article shows how experiments at the Coweeta Hydrologic Laboratory in North Carolina have deepened our understanding of the ways in which forested catchments respond to land use change. Drainage-basin hydrology is popular topic, often at AS. Human impact on stream discharge as a result of changes in vegetation cover is an important theme.

Burt, T.P. 1989. Forest hydrology and ecology at Coweeta. Hydrological Processes 3: 289-293.

Abstract
A review of the Coweeta Symposium volume.

Burt, T.P., and W.T. Swank. 1992. Flow frequency responses to hardwood-to-grass conversion and subsequent succession. Hydrological Processes 6(2): 179-188.

Abstract
A 8-9 ha (22 acre) catchment at the Coweeta Hydrologic Laboratory in western North Carolina was cleared of hardwood forest in 1958 and 1959 and seeded to Kentucky 31 fescue grass in 1959 and 1960. Grass production was high in years when fertilizer was applies and water was very similar to that expected from the original forest cover. As grass production declined, so water yields rose, with important increases in the magnitude of both low frequency flows and, particularly, in baseflow. In 1967 and 1968, when all vegetation was deadened in the catchment, the discharge levels in all flow frequency classes were higher. Natural vegetation was then allowed and water yields gradually declined towards the expected level, although there remained a tendency for winter flows to remain higher, and for summer flows to be lower than expected. This paper updated the earlier work of Hibbert (1969) and uses flow duration curves to extend his results

Burt, Tim & Miniat, Chelcy & H. Laseter, S & T. Swank, W. (2017). Changing patterns of daily precipitation totals at the Coweeta Hydrologic Laboratory, North Carolina, USA: COWEETA DAILY RAINFALL. International Journal of Climatology. . 10.1002/joc.5163.

Abstract
A pattern of increasing frequency and intensity of heavy rainfall over land has been documented for several temperate regions and is associated with climate change. This study examines the changing patterns of daily precipitation at the Coweeta Hydrologic Laboratory, North Carolina, USA, since 1937 for four rain gauges across a range of elevations. We analyse seasonal total rainfall, number of rain days and the frequency of heavy rainfall. We compare these with several teleconnections, including the Bermuda High Index (BHI), the West BHI, the North Atlantic Oscillation (NAO) and the El Niño-Southern Oscillation. Our data show a tendency for increased variability, including major periods of drought, with fewer rain days recently, especially in summer. Only autumn tended to have increases in rainfall frequency and magnitude; this is the season when orographic enhancement is at its strongest. The major driver of precipitation at Coweeta is the strength of the Bermuda High. The strength of the NAO is important in summer. The results are relevant to the southeast United States in general, given that the region comes under the influence of similar air masses during the year. The findings are applicable to the wider Appalachian Mountains and to other mountainous regions where there is significant orographic enhancement.

Burton, A.J. K.S. Pregitzer, R.W. Ruess, R.L. Hendrick, and M.F. Allen. 2002. Root respiration in North American forests: effects of nitrogen concentration and temperature across biomes. Oecologia (2002) 131:559-568.

Abstract
Root respiration rates have been shown to be correlated with temperature, and root N concentration in studies of individual forest types or species, but it is not known how universal these relationships are across forest species adapted to widely different climatic and edaphic conditions. In order to test for broad, cross-species relationships, we measured fine root respiration, as O2 consumption, over a range of temperatures on excised root samples from ten forested study sites across North America in 1997. Significant differences existed among study sites in root respiration rates, with patterns among sites in respiration rate at a given temperature corresponding to differences among sites in fine root N concentrations. Root respiration rates were highly correlated with root N concentrations at all measurement temperatures (r2>0.81, P<01, for 6, 18 and 24+C). Lower root respiration rates in gymnpsperms than in angiosperms were largely explained by lower fine root N .concentrations in gymnosperms, and root N concentrations and respiration rates (at a given temperature) tended to be lower at warm sites (New Mexico, Florida, and Georgia) than at cool sites with short growing seasons (Michigan and Alaska). Root respiration rates increased exponentially with temperature at all sites. The Q10 for root respiration ranged from 2.4 to 3.1, but there were no significant differences among the forest types. The average Q10^s or gymnosperms (Q10=2.7) and angiosperms (Q10=2.6) were almost identical, as were the average Q10^s for roots of ectomycorrhizal species (Q10=2.7) and arbuscular mycorrhizal species (Q10=2.6). In 1998, fine root respiration at the study sites was measured in the field as CO2 production at ambient soil temperature. Respiration rates under field conditions ere dependent on both ambient soil temperature and root N concentration. Relationships between respiration (adjusted for temperature) and root N concentration for the field measurements were similar to those observed in the 1997 laboratory experiments. For root respiration in tree species, it appears that basic relationships with temperature and nitrogen exist cross species and biomes.

Butler, S.M., A.S. White, K.J. Elliott, and R.S. Seymour. 2014. Disturbance history and stand dynamics in secondary and old growth forests of the Southern Appalachian Mountains, USA. Journal of the Torrey Botanical Society 141(4):189-204

Abstract
Understanding the patterns of past disturbance allows further insight into the complex composition, structure, and function of current and future forests, which is increasingly important in a world where disturbance characteristics are changing. Our objectives were to define disturbance causes, rates (percent disturbance per decade), magnitudes and frequency (time since last disturbance) for both secondary and old-growth mixed-oak stands, and to determine if all mixed oak stands experience similar disturbance history. The study was located in two southern Appalachian forests in western North Carolina, USA: Coweeta Hydrologic Laboratory, a 2,185 ha experimental forest with some history of harvesting, and the Joyce Kilmer Wilderness, a 6,805 ha old-growth forest with no known harvesting. We used dendroecological techniques to evaluate the disturbance histories and create chronologies of these mixed-oak forests. Average decadal disturbance rates ranged from 4.3% to 13.8%, similar to rates common in eastern temperate forests (5% to 20%). The decades of peak recruitment common to several stands were the 1840s, which coincides with the historical accounts of a hurricane; the 1900s through the 1940s, which coincide with logging and elimination of Castanea dentata (Marshall) Borkh. by chestnut blight; and the 1960s, which coincides with drought and an elm spanworm infestation. The large peaks of disturbance were often synchronous and widespread, affecting stands across both Coweeta and Joyce Kilmer. However, there were also scattered pulses of disturbance unique to single stands, suggesting that localized events also played a role in the disturbance dynamics. Periods of constant low rates of disturbance present in all stands also indicate the importance of small canopy gaps in these forests. We found that stands similar in disturbance regimes were also similar in species composition. Results from our study provide information on how past disturbances, both regional and local events, have shaped the current forest. This understanding could help inform models to better predict how forests might respond to future climate (e.g., rising temperatures and increasing precipitation variability) and disturbance patterns (e.g., more frequent and severe events).

Caldwell, P. V., Miniat, C. F., Elliott, K. J., Swank, W. T., Brantley, S. T. and Laseter, S. H. (2016), Declining water yield from forested mountain watersheds in response to climate change and forest mesophication. Glob Change Biol, 22: 2997–3012. doi:10.1111/gcb.13309

Abstract
Climate change and forest disturbances are threatening the ability of forested mountain watersheds to provide the clean, reliable, and abundant fresh water necessary to support aquatic ecosystems and a growing human population. Here, we used 76 years of water yield, climate, and field plot vegetation measurements in six unmanaged, reference watersheds in the southern Appalachian Mountains of North Carolina, USA to determine whether water yield has changed over time, and to examine and attribute the causal mechanisms of change. We found that annual water yield increased in some watersheds from 1938 to the mid-1970s by as much as 55%, but this was followed by decreases up to 22% by 2013. Changes in forest evapotranspiration were consistent with, but opposite in direction to the changes in water yield, with decreases in evapotranspiration up to 31% by the mid-1970s followed by increases up to 29% until 2013. Vegetation survey data showed commensurate reductions in forest basal area until the mid-1970s and increases since that time accompanied by a shift in dominance from xerophytic oak and hickory species to several mesophytic species (i.e., mesophication) that use relatively more water. These changes in forest structure and species composition may have decreased water yield by as much as 18% in a given year since the mid-1970s after accounting for climate. Our results suggest that changes in climate and forest structure and species composition in unmanaged forests brought about by disturbance and natural community dynamics over time can result in large changes in water supply.

Caldwell, P., Segura, C., Laird, S.G., Sun, G., McNulty, S.G., Sandercock, M., Boggs, J. and Vose, J.M. 2014. Short-term stream water temperature observations permit rapid assessment of potential climate change impacts. Hydrological Processes. (DOI: 10.1002/hyp.10358)

Abstract
Assessment of potential climate change impacts on stream water temperature (Ts) across large scales remains challenging for resource managers because energy exchange processes between the atmosphere and the stream environment are complex and uncertain, and few long-term datasets are available to evaluate changes over time. In this study, we demonstrate how simple monthly linear regression models based on short-term historical Ts observations and readily available interpolated air temperature (Ta) estimates can be used for rapid assessment of historical and future changes in Ts. Models were developed for 61 sites in the southeastern USA using =18 months of observations and were validated at sites with longer periods of record. The Ts models were then used to estimate temporal changes in Ts at each site using both historical estimates and future Ta projections. Results suggested that the linear regression models adequately explained the variability in Ts across sites, and the relationships between Ts and Ta remained consistent over 37 years. We estimated that most sites had increases in historical annual mean Ts between 1961 and 2010 (mean of +0.11°C decade^-1). All 61 sites were projected to experience increases in Ts from 2011 to 2060 under the three climate projections evaluated (mean of +0.41°C ^1). Several of the sites with the largest historical and future Ts changes were located in ecoregions home to temperature-sensitive fish species. This methodology can be used by resource managers for rapid assessment of potential climate change impacts on stream water temperature.

Caldwell, P.V., Kennen, J.G., Sun, G., Kiang, J.E., Butcher, J.B., Eddy, M.C., Hay, L.E., LaFontaine, J.H., Hain, E.F., Nelson, S.A. and McNulty, S.G. 2015. A comparison of hydrologic models for ecological flows and water availablity. Ecohydrology. (DOI: 10.1002/eco.1602)

Abstract
Robust hydrologic models are needed to help manage water resources for healthy aquatic ecosystems and reliable water supplies for people, but there is a lack of comprehensive model comparison studies that quantify differences in streamflow predictions among model applications developed to answer management questions. We assessed differences in daily streamflow predictions by four fine-scale models and two regional-scale monthly time step models by comparing model fit statistics and bias in ecologically relevant flow statistics (ERFSs) at five sites in the Southeastern USA. Models were calibrated to different extents, including uncalibrated (level A), calibrated to a downstream site (level B), calibrated specifically for the site (level C) and calibrated for the site with adjusted precipitation and temperature inputs (level D). All models generally captured the magnitude and variability of observed streamflows at the five study sites, and increasing level of model calibration generally improved performance. All models had at least 1 of 14 ERFSs falling outside a +/−30% range of hydrologic uncertainty at every site, and ERFSs related to low flows were frequently over-predicted. Our results do not indicate that any specific hydrologic model is superior to the others evaluated at all sites and for all measures of model performance. Instead, we provide evidence that (1) model performance is as likely to be related to calibration strategy as it is to model structure and (2) simple, regional-scale models have comparable performance to the more complex, fine-scale models at a monthly time step.

Camp, C., Peterman, W., Milanovich, J., Lamb, T., Maerz, J., Wake, D. 2009. A new genus and species of lungless salamander (family Plethodontidae) from the Appalachian highlands of the south-eastern United States. Journal of Zoology, 279(1): 86-94

Abstract
We describe a striking new species of the lungless salamander family Plethodontidae from the Appalachian foothills of northern Georgia, USA. This miniature species, c. 25–26mm (adult standard length), is so distinctive genetically and morphologically that we erect a new genus, the first new genus of amphibian described from the US in nearly 50 years. It is unique among plethodontids from eastern North America in displaying sexual colour dimorphism. Although certain miniaturized plethodontids exhibit a reduced number (four) of digits on the pes, this species possesses a full complement of five toes. A plethodontid phylogeny derived from mitochondrial and nuclear DNA sequences places it in the tribe Spelerpini as the sister taxon to Eurycea. Genetic divergence between the new species and Eurycea for the nuclear gene Rag-1 (4.7%) is among the higher levels observed between long-established spelerpine genera (2.6–5.3%). This new form appears to be rare and is of immediate conservation concern.

Campbell, P.K.E., Middleton, E.M., Thome, K.J., Kokaly, R.F., Huemmrich, K.F., Lagomasino, D., Novick, K.A. and Brunsell, N.A. 2013. Hyperion reflectance time series at calibration and validation sites: stability and sensitivity to seasonal dynamics. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. 6(2):276-290. (DOI: 10.1109/JSTARS.2013.2246139)

Abstract
This study evaluated Earth Observing 1 (EO-1) Hyperion reflectance time series at established calibration sites to assess the instrument stability and suitability for monitoring vegetation functional parameters. Our analysis using three pseudo-invariant calibration sites in North America indicated that the reflectance time series are devoid of apparent spectral trends and their stability consistently is within 2.5-5 percent throughout most of the spectral range spanning the 12+ year data record. Using three vegetated sites instrumented with eddy covariance towers, the Hyperion reflectance time series were evaluated for their ability to determine important variables of ecosystem function. A number of narrowband and derivative vegetation indices (VI) closely described the seasonal profiles in vegetation function and ecosystem carbon exchange (e.g., net and gross ecosystem productivity) in three very different ecosystems, including a hardwood forest and tallgrass prairie in North America, and a Miombo woodland in Africa. Our results demonstrate the potential for scaling the carbon flux tower measurements to local and regional landscape levels. The VIs with stronger relationships to the CO2 parameters were derived using continuous reflectance spectra and included wavelengths associated with chlorophyll content and/or chlorophyll fluorescence. Since these indices cannot be calculated from broadband multispectral instrument data, the opportunity to exploit these spectrometer-based VIs in the future will depend on the launch of satellites such as EnMAP and HyspIRI. This study highlights the practical utility of space-borne spectrometers for characterization of the spectral stability and uniformity of the calibration sites in support of sensor cross-comparisons, and demonstrates the potential of narrowband VIs to track and spatially extend ecosystem functional status as well as carbon processes measured at flux towers.

Carter, T., C.R. Jackson, A. Rosemond, C. Pringle, D. Radcliffe, W. Tollner, J. Maerz, D. Leigh. A. Trice. 2009. Beyond the urban gradient: barriers and opportunities for timely studies of urbanization effects on aquatic ecosystems. Journal of the North American Benthological Society, 28(4):1038-1050

Abstract
Many studies have shown that streams degrade in response to urbanization in the watershed. These studies often are based on use of biotic and abiotic variables to measure stream health across a gradient of land cover/land use. The results of these studies can be applied to other urban systems, but often fail to provide a mechanistic understanding of the urban impact, in part, because of the nature of the experimental design. We analyzed the advantages and disadvantages of using environmental gradient studies to further understanding of urban stream systems. We also evaluated alternative experimental design approaches, including best management practice monitoring, long-term watershed studies, pairedwatershed studies, and before–after control–impact studies, which could be used to complement the gradient approach. We illustrate these theoretical discussions with an urban paired-watershed case study in the Etowah watershed in northern Georgia. Our goal is to move experimental designs in a direction that will further our mechanistic understanding of the effects of existing urbanization on aquatic ecosystems and will provide opportunities to evaluate stream responses to environmentally sensitive urban land cover.

Cataneo, R. 1969.A method for estimating rainfall rate-radar reflectivity relationships. Journal of Applied Meteorology 8(5): 815-819.

Abstract
Raindrop-size distributions obtained with the drop camera have been used to determine rainfall rate-radar reflectivity relationships for nine different locations throughout the world. Since the climates sampled were quite varied, and extrapolation of the Z-R relationships to other areas of the world with similar drop-spectra climates can be performed. Two climatic parameters, the mean annual percent of rain days that are thunderstorm days, and the mean annual relative humidity at 0.5 km above ground, were found to be highly correlated with the coefficient A and exponent b in the Z-R equation, Z=ARb. Regression equations based on the two climatic parameters were determined, permitting an estimation of the Z-R relationship for any area once the parameters are obtained.

Cataneo, R., and D.L. Vercellino. 1972. Estimating rainfall rate-radar reflectivity relationships for individual storms. Journal of Applied Meteorology 2(1): 211-213.

Abstract
In order to improve the accuracy with which radar estimates rainfall rates and amounts, a method has been developed whereby the rainfall rate-radar reflectivity relationships may be estimated for approaching precipitation. The estimating equation is based on atmospheric parameters which may be obtained in advance of precipitation, from standard radiosonde data. Comparisons are made between the present model and other methods concerning their effectiveness in determining appropriate rainfall rate-radar reflectivity relationships .

Cataneo, R., and G. Stout. 1968. Raindrop-size distributions in humid continental climates, and associated rainfall rate-radar reflectivity relationships. Journal of Applied Meteorology 7(5): 901-907.

Abstract
Raindrop-size spectra obtained with the raindrop camera have been analyzed from two locations, Island Beach, N.J., and Franklin, N.C. The spectra were analyzed with respect to total number of drops per average rain rate per cubic meter of sample, geometic mean diameter, mode diameter, and the diameter of drops at which half the liquid water content lies above that diameter and half below. The results indicate that the distributions from both locations are quite similar. Rainfall rate-radar reflectivity relationships indicate that cold frontal rains, upslope rains, and tropical storm rains generally have smaller drops.

Cecala, K. K., J. C. Maerz, B. J. Halstead, J. R. Frisch, T. L. Gragson, J. Hepinstall-Cymerman, D. S. Leigh, C. R. Jackson, J. T. Peterson, and C. M. Pringle. 2018. Multiple drivers, scales, and interactions influence southern Appalachian stream salamander occupancy. Ecosphere 9(3):e02150. 10.1002/ecs2.2150

Abstract
Understanding how factors that vary in spatial scale relate to population abundance is vital to forecasting species responses to environmental change. Stream and river ecosystems are inherently hierarchical, potentially resulting in organismal responses to fine-scale changes in patch characteristics that are conditional on the watershed context. Here, we address how populations of two salamander species are affected by interactions among hierarchical processes operating at different scales within a rapidly changing landscape of the southern Appalachian Mountains. We modeled reach-level occupancy of larval and adult black-bellied salamanders (Desmognathus quadramaculatus) and larval Blue Ridge two-lined salamanders (Eurycea wilderae) as a function of 17 different terrestrial and aquatic predictor variables that varied in spatial extent. We found that salamander occurrence varied widely among streams within fully forested catchments, but also exhibited species-specific responses to changes in local conditions. While D. quadramaculatus declined predictably in relation to losses in forest cover, larval occupancy exhibited the strongest negative response to forest loss as well as decreases in elevation. Conversely, occupancy of E. wilderae was unassociated with watershed conditions, only responding negatively to higher proportions of fast-flowing stream habitat types. Evaluation of hierarchical relationships demonstrated that most fine-scale variables were closely correlated with broad watershed-scale variables, suggesting that local reach-scale factors have relatively smaller effects within the context of the larger landscape. Our results imply that effective management of southern Appalachian stream salamanders must first focus on the larger scale condition of watersheds before management of local-scale conditions should proceed. Our findings confirm the results of some studies while refuting the results of others, which may indicate that prescriptive recommendations for range-wide management of species or the application of a single management focus across large geographic areas is inappropriate.

Cecala, K. K., Lowe, W. H. and Maerz, J. C. (2014), Riparian disturbance restricts in-stream movement of salamanders. Freshwater Biology, 59: 2354-2364. doi: 10.1111/fwb.12439

Abstract
1. Long-term population persistence or population rescue require dispersal from other source populations. Barriers to movement can effectively fragment and isolate populations, reducing persistence and recolonisation. For stream organisms that depend heavily on movement within dendritic networks, research is needed to identify and estimate the effects of such barriers on connectivity. 2. We used capture–mark–recapture of displaced larval and adult salamanders to estimate return rates across gaps (length 13–85 m) in the riparian canopy and thus to assess the fragmentation of salamander populations within otherwise fully forested catchments. 3. Relative to salamanders in fully forested reaches, displaced salamanders were 86% less likely to return to their capture location when required to cross gaps in the canopy as short as 13 m, and the likelihood of return declined with increasing gap length. The effects of gaps on return rates were consistent among life stages and for up- and downstream movement. 4. Our study suggests that riparian disturbance can reduce permeability to salamanders, even in the absence of additional land-use change. Because anthropogenic features, such as roads and powerlines, frequently cross small streams, the accumulation of apparently small land-cover changes has the potential to reduce continuous populations to small fragments with limited connectivity.

Cecala, K.K. and Maerz, J.C. 2015. Context-dependent responses to light contribute to salamander responses to landscape disturbances. Canadian Journal of Zoology 94:7-13. 10.1139/cjz-2015-0111

Abstract
Behaviour often regulates population responses to environmental change, but linking behavioural responses to population patterns can be challenging because behavioural responses are often context-dependent, have an instinctive component, and yet may be modified by experience. Black-bellied salamanders (Desmognathus quadramaculatus, Holbrook 1840) occupy forested streams where dense canopies create cool, dark environments. Because riparian deforestation negatively affects salamander population connectivity yet some individuals choose to persist in these gaps, we sought to evaluate whether phototaxis could explain these patterns and whether phototactic behaviour would be influenced by experience (capture from forested or deforested areas) or context (refuge type and availability). Our results demonstrated that D. quadramaculatus larvae exhibited negative phototaxis but that larvae from forested streams exhibited stronger negative phototaxis than individuals from deforested streams. Larvae also selected habitat closer to light when refuge was available. Our results show that light alters larval D. quadramaculatus habitat use, but the magnitude of that effect depends on refuge availability and experience with well-lit conditions associated with forest removal. As human activities reduce canopy cover and refuge availability, negative phototaxis may be one explanation for behavioural barriers to movement. Ultimately, the ability of salamanders to exhibit behavioural plasticity will determine their potential for local adaptation facilitating persistence in the face of environmental change.

Chamblee, J.F., Dehring, C.A., Depken, C.A. 2008. Watershed development restrictions and land prices: Empirical evidence from southern Appalachia. Regional Science and Urban Economics. 39: 287-296

Abstract
The State of North Carolina's Water Supply Watershed Protection Act of 1989 required local governments to adopt land use measures in watersheds to protect the water supply emanating from the watersheds. We examine vacant land prices in the Ivy River watershed of Buncombe County, NC, at the time such regulation took effect. Our results suggest that costs of watershed development restrictions are borne primarily by those vacant land owners in the watershed for whom the development restrictions make land subdivision infeasible.We find benefits accruing to land owners on the public water supply or who are adjacent to creeks.

Chamblee, John F., Carolyn A. Dehring, Craig A. Depken II and Joseph R. Nicholson. 2015. Water Contamination, Land Prices, and the Statute of Repose. The Journal of Real Estate, Finance, and Economics. 51(3). (DOI: 10.1007/s11146-015-9514-3)

Abstract
We examine how water contamination risk from an inactive hazardous waste site is capitalized into surrounding vacant land prices. After public knowledge of the first instance of off-site contamination, we find that shallow groundwater contamination potential is negatively capitalized into land prices, as is proximity to a known contaminated well. Public knowledge of off-site contamination and associated land price changes occur after the North Carolina’s 10-year statute of repose. Our findings raise questions concerning such statutes when environmental contamination has a long latency period, especially given a recent Supreme Court ruling that Superfund law does not preempt state statutes of repose.

Chandler, R. & Hepinstall-Cymerman, J. (2016), Estimating the spatial scales of landscape effects on abundance, Landscape Ecol, 31:1383, doi:10.1007/s10980-016-0380-z

Abstract
Context Spatial variation in abundance is influenced by local- and landscape-level environmental variables, but modeling landscape effects is challenging because the spatial scales of the relationships are unknown. Current approaches involve buffering survey locations with polygons of various sizes and using model selection to identify the best scale. The buffering approach does not acknowledge that the influence of surrounding landscape features should diminish with distance, and it does not yield an estimate of the unknown scale parameters. Objectives The purpose of this paper is to present an approach that allows for statistical inference about the scales at which landscape variables affect abundance. Methods Our method uses smoothing kernels to average landscape variables around focal sites and uses maximum likelihood to estimate the scale parameters of the kernels and the effects of the smoothed variables on abundance. We assessed model performance using a simulation study and an avian point count dataset. Results The simulation study demonstrated that estimators are unbiased and produce correct confidence interval coverage except in the rare case in which there is little spatial autocorrelation in the landscape variable. Canada warbler abundance was more highly correlated with site-level measures of NDVI than landscape-level NDVI, but the reverse was true for elevation. Canada warbler abundance was highest when elevation in the surrounding landscape, defined by an estimated Gaussian kernel, was between 1300 and 1400 m. Conclusions Our method provides a rigorous way of formally estimating the scales at which landscape variables affect abundance, and it can be embedded within most classes of statistical models.

Chandler, Richard B., Hepinstall-Cymerman, Jeff, Merker, Samuel, Abernathy-Conners, Heather, Cooper, Robert J. (2018). Characterizing spatio-Temporal variation in survival and recruitment with integrated population models. The Auk. 135. 409-426. 10.1642/AUK-17-181.1.

Abstract
Efforts to understand population dynamics and identify high-quality habitat require information about spatial variation in demographic parameters. However, estimating demographic parameters typically requires labor-intensive capture-recapture methods that are difficult to implement over large spatial extents. Spatially explicit integrated population models (IPMs) provide a solution by accommodating spatial capture-recapture (SCR) data collected at a small number of sites with survey data that may be collected over a much larger extent. We extended the spatial IPM framework to include a spatio-Temporal point process model for recruitment, and we applied the model to 4 yr of SCR and distance-sampling data on Canada Warblers (Cardellina canadensis) near the southern extent of the species' breeding range in North Carolina, USA, where climate change is predicted to cause population declines and distributional shifts toward higher elevations. To characterize spatial variation in demographic parameters over the climate gradient in our study area, we modeled density, survival, and per capita recruitment as functions of elevation. We used a male-only model because males comprised >90% of our point-count detections. Apparent survival was low but increased with elevation, from 0.040 (95% credible interval CI: 0.0032-0.12) at 900 m to 0.29 (95% CI: 0.16-0.42) at 1,500 m. Recruitment was not strongly associated with elevation, yet density varied greatly, from <0.03 males ha?¹ below 1,000 m to >0.2 males ha?¹ above 1,400 m. Point estimates of population growth rate were <1 at all elevations, but 95% CIs included 1. Additional research is needed to assess the possibility of a long-Term decline and to examine the effects of abiotic variables and biotic interactions on the demographic parameters influencing the species' distribution. The modeling framework developed here provides a platform for addressing these issues and advancing knowledge about spatial demography and population dynamics.

Cheever, B.M., E.B. Kratzer, and J.R. Webster. 2012. Immobilization and mineralization of N and P by heterotrophic biofilms during leaf decomposition. Freshwater Science 31:133-147.

Abstract
According to theory, the rate and stoichiometry of microbial mineralization depend, in part, on nutrient availability. For microbes associated with leaves in streams, nutrients are available from both the water column and the leaf. Therefore, microbial nutrient cycling may change with nutrient availability and during leaf decomposition. We explored spatial and temporal patterns of mineralization by heterotrophic microbes by placing packs of red maple leaves at sites in 5 Appalachian streams spanning a range of N and P availability. We collected packs 4 times from each site. Leaf disks from these packs were incubated in microcosms, and uptake rates and steady-state concentrations of NH + and soluble reactive P (SRP) were used to calculate mineralization rates. N uptake peaked between 50 and 60 d, whereas P uptake peaked ,10 d later. Clear patterns were found for fungal biomass-specific uptake or mineralization fluxes of either nutrient over time or space, but the microbes grown in the site with the lowest nutrient availability had the highest fungal biomass-specific cycling. The ability of microbes to access nutrients from their substrate may prevent dissolved nutrient availability from being a strong driver of microbial nutrient cycling.

Cheever, B.M., Webster, J.R., Bilger, E. and Thomas, S.A. 2013. The relative importance of exogenous and substrate derived nitrogen for microbial growth during leaf decomposition. Ecology. 94:1614-1625. (DOI: 10.1890/12-1339.1)

Abstract
Heterotrophic microbes colonizing detritus obtain nitrogen (N) for growth by assimilating N from their substrate or immobilizing exogenous inorganic N. Microbial use of these two pools has different implications for N cycling and organic matter decomposition in the face of the global increase in biologically available N. We used sugar maple leaves labeled with 15 N to differentiate between microbial N that had been assimilated from the leaf substrate (enriched with 15 N) or immobilized from the water (natural abundance 15 N: 14 N) in five Appalachian streams ranging in ambient NO 3 -N concentrations from about 5 to 900 l gNO 3 - N/L. Ambient NO 3 concentration increased sugar maple decomposition rate but did not influence the proportion of microbial N derived from substrate or exogenous pools. Instead, these proportions were strongly influenced by the percentage of detrital ash-free dry mass (AFDM) remaining. Substrate-derived N made up a large proportion of the microbial N after the first 24 h in all streams. Detrital and microbial isotopic 15 N signatures approached that of the water as decomposition progressed in all streams, suggesting that exogenous N may be the predominant source of N for meeting microbial requirements even when exogenous N concentrations are low. Our results support predictions of more rapid decomposition of organic matter in response to increased N availability and highlight the tight coupling of processes driving microbial N cycling and organic matter decomposition.

Chellemi, D.O., and K.O. Britton. 1992. Influence of canopy microclimate on incidence and severity of dogwood anthracnose. Canadian Journal of Botany 70: 1093-1096.

Abstract
Incidence and severity of dogwood anthracnose within the interior and exterior canopies of exposed and understory dogwood trees were recorded over a 53-day period during the summer of 1990. Concurrent measurements of vapor pressure deficit, air temperature, evaporative potential, and photosynthetically active radiation within the canopies were also recorded. Disease severity was significantly different among all canopy locations, with the lowest severity in exterior canopies of exposed trees and the greatest severity in canopies of understory trees. Of the climatic variables measured, evaporative potential provided the most consistent contrast among microclimates at the various canopy locations. Disease incidence and severity were greater in canopies associated with low levels of evaporative potential.

Chellemi, D.O., K.O. Britton, and W.T. Swank. 1992. Influence of site factors on dogwood anthracnose in the Nantahala Mountain range of western North Carolina. Plant Disease 76(9): 915-918.

Abstract
Sixty-five 0.08-ha plots located within the Nantahala Mountain range of western North Carolina were surveyed for dogwood anthracnose, caused by Discula destructiva. The incidence of disease and disease severity (extent of foliar symptoms and limb dieback) within canopies of Cornus florida was determined for all trees with a diameter of 1.0 cm or greater at 1.37 m aboveground.

Chen, T.H., G.M. Hornberger, A.J. Jakeman, and W.T. Swank. 1995. The performance of different loss models in the simulation of streamflow. Environmetrics. 6: 479-484.

Abstract
The performance of a new approach to separate hydrographs and parametrize their response behavior for describing the rainfall-runoff process was examined using data from Coweeta Watershed 36 (USA) and Queanbeyan River (Australia). The model tested consists of two modules; the non-linear module represents the rainfall-loss process and the linear module converts excess rainfall to streamflow. Evaluations of three different formulations of the rainfall-loss model showed good estimation and simulation performance at Coweeta for all three cases but Case 2 was judged as superior. For Queanbeyan, Case 2 was again the best for model estimation and Case 1 provided reasonably good performance for model simulation.

Cho, S., and D.H. Newman. 2005. Spatial analysis of rural land development. Forest Policy and Economics. 7: 732-744.

Abstract
This article examines patterns of rural land development and density using spatial econometric models with the application of Geographical Information System (GIS). The cluster patterns of both development and high-density development indicate that the spatially continuous expansions of development and high-density development exist in relatively remote rural areas. The results also revealed that a closer distance to roads, a closer distance to cities, greater access to streams and rivers, higher elevations, and greater proportions of flat area are valued highly in rural land development.

Cho, S., D.H. Newman, and D.N, Wear. 2005. Community Choices and Housing Demands: A Spatial Analysis of the Southern Appalachian Highlands. Housing Studies. 20(4): 549-569.

Abstract
This paper examines housing demand using an integrated approach that combines residential decisions about choices of community in the Southern Appalachian region with the application of a Geographical Information System (GIS). The empirical model infers a distinctive heterogeneity in the characteristics of community choices. The results also indicate that socioeconomic motives strongly affect urban housing demands while environmental amenities affect those of rural housing demand.

Cho, S., D.H. Newman, and D.N. Wear. 2003. Impacts of second home development on housing prices in the southern Appalachian highlands. Review of Urban & Regional Development Studies (RURDS). 15(3): 208-225.

Abstract
This study estimates the value of socioeconomic, spatial and environmental attributes on housing prices of both urban and rural communities in the primary and second home areas of the Southern Appalachian Highlands, using the hedonic model property price model. Distance and environmental attributes are valued more heavily in the rural communities of the second home area than in the urban communities of the primary home area. The effect of second homes on housing prices is mainly evident in the rural communities. Second home development impacts a home+s value by US

Cho, S., D.H. Newman, and J.M. Bowker. 2005. Measuring rural homeowners' willingness to pay for land conservation easements. Forest Policy and Economics. 7: 757-770.

Abstract
Rapid growth of rural communities in the Blue Ridge Mountains of Macon County, North Carolina has been giving rise to concerns over declining environmental quality and increasing need for land-use policy. This paper examines willingness to pay (WTP) for hypothetical conservation easements as an alternative land-use policy for the county. Despite the fact that Macon County has struggled to adopt any land-use policy, the stated WTP for conservation easements of our study shows that homeowners potentially value the use of conservation easements. Estimated household¼s WTP to participate in an easement program ranges from 10.97 dollars to 21.79 dollars per year per household depending on modeling assumptions. Aggregate county WTP ranges from 360,772 dollars to 109,825 dollars depending on aggregation stance. This suggests a range of 53v175 acres entering the program per year, and a consequent decline in the rate of land conversion, compared to the 1987v1997 period, of 14v46%.

Chung, K., J.B. Wallace, and J.W. Grubaugh. 1993. The impact of insecticide treatment on abundance, biomass and production of litterbag fauna in a headwater stream: a study of pretreatment, treatment and recovery. Limnologica. 28(2): 93-106.

Abstract
The insecticide methoxychlor was applied seasonally for three years to a small headwater stream at Coweeta Hydrologic Laboratory. Invertebrate fauna colonizing litterbags and litter processing rates in the treatment and a reference stream were examined prior to and during treatment and for two recovery years. During treatment, leaf processing rates were less than 50% of rates in pretreatment years. Invertebrate fauna was dominated by large numbers of small collector-gatherers (primarily non-insects) and predators, whereas insect shredders were virtually eliminated. During the first recovery year, populations of non-insect taxa remained high and many insect taxa, especially those with long life cycles, remained absent or rare. Reappearance of the insect community, especially insect shredders, during the second recovery year was accompanied by restoration of leaf processing rates. The recovery process of macroinvertebrate communities in this stream appeared to result from the proximity of numerous headwater streams within the Coweeta basin, which provide stable source populations.

Chung, N., Suberkropp, K. 2008. Influence of shredder feeding and nutrients on fungal activity and community structure in headwater streams. Fundamental and Applied Limnology, 173(1): 35-46.

Abstract
In stream detrital food webs, interactions occur between aquatic hyphomycetes associated with decomposing leaves and shredders consuming those leaves. However, few studies have examined how the feeding activity of shredders affects aquatic hyphomycetes. We examined the effect of shredder feeding on aquatic hyphomycete communities associated with submerged leaves in two southern Appalachian headwater streams in Coweeta Hydrologic Laboratory, North Carolina, USA. Coarse (allowing shredder access) and fi ne (preventing shredder access) mesh litter bags containing red maple (Acer rubrum) leaves were placed in the treatment stream (C54) which was enriched with nitrogen (N) and phosphorus (P), and in the reference stream (C53) and were retrieved monthly. Both shredder feeding and nutrient enrichment enhanced breakdown rates. The breakdown rates of leaves in coarse mesh bags in the reference stream (k = 0.0275) and fi ne mesh bags in the nutrient enriched stream (k = 0.0272) were not signifi cantly different, suggesting that the higher fungal activity stimulated by nutrient enrichment could increase the relative contribution of fungi to leaf breakdown to the level similar to that of shredders in the reference stream. Macroinvertebrate abundance and biomass were higher in the litter bags submerged in the treatment stream. Fungal sporulation rates and biomass were higher in the treatment stream than in the reference stream, but neither fungal biomass nor sporulation rate was affected by shredder feeding in either stream. The enrichment with N and P altered fungal community composition more than shredder feeding. Species richness was higher in the nutrient enriched stream than in the reference stream, and fungal assemblages from fi ne and coarse mesh bag treatments within a stream were more similar to each other than the fungal assemblages from the same mesh bag treatments but from different streams.

Clapp, C.E. 1956. Regulating streamflow from small watersheds. The Forest Farmer 16(2): 18-19.

Abstract
An introduction to some principles of watershed management based on Coweeta research.

Clark, J, L. Horvath, and M. Lewis. 2001. On the estimation of spread rate for a biological population. Statistics & Probability Letters. 51: 225-234

Clark, J. S. (2016), Why species tell more about traits than traits about species: predictive analysis. Ecology, 97: 1979–1993. doi:10.1002/ecy.1453

Abstract
Trait analysis aims to understand relationships between traits, species diversity, and the environment. Current methods could beneft from a model-based probabilistic framework that accommodates covariance between traits and quantifes contributions from inherent trait syndromes, species interactions, and responses to the environment. I develop a model-based approach that separates these effects on trait diversity. Application to USDA Forest Inventory and Analysis (FIA) data in the eastern United States demonstrates an apparent paradox, that the analysis of species better explains and predicts traits than does direct analysis of the traits themselves; trait data contain less, not more, information than species on environmental responses. Whereas variation in some traits is dominated by inherent syndromes (tendency for certain traits to be associated with others within an individual and species), others are strongly controlled by variation in species diversity. There is substantial variation in environmental control on trait patterns, between traits and regionally. In terms of environmental response traits do not aggregate into defned plant functional types, as would be desirable for models.

Clark, J.S. 1998. Why Trees Migrate So Fast: Confronting Theory with Dispersal Biology and the Paleorecord. The American Naturalist. 152(2): 204-224.

Abstract
Reid's paradox describes the fact that classical models cannot account for the rapid spread of trees at the end of the Pleistocene. I use field estimates of seed dispersal with an integrodifference equation and simulation models of population growth to show that dispersal data are compatible with rapid spread. Dispersal estimates lay to rest the possibility that rapid spread occurred by diffusion. The integrodifference model predicts that, if the seed shadow has a long "fat" tail, then rapid spread is possible, despite short average dispersal distances. It further predicts that velocity is more sensitive to life history than is classical diffusion. The inference of rapid spread, together with lack of obvious life-history effects, suggests velocities may have not reached their potentials, being stalled by rates of climate change, geography, or both.

Clark, J.S. 2005. Why environmental scientists are becoming Bayesians. Ecology Letters. 8: 2-14.

Abstract
Advances in computational statistics provide a general framework for the high-dimensional models typically needed for ecological inference and prediction. Hierarchical Bayes (HB) represents a modelling structure with capacity to exploit diverse sources of information, to accommodate influences that are unknown (or unknowable), and to draw inference on large numbers of latent variables and parameters that describe complex relationships. Here I summarize the structure of HB and provide examples for common spatiotemporal problems. The flexible framework means that parameters, variables and latent variables can represent broader classes of model elements than are treated in traditional models. Inference and prediction depend on two types of stochasticity, including (1) uncertainty, which describes our knowledge of fixed quantities, it applies to all ¬unobservables¼ (latent variables and parameters), and it declines asymptotically with sample size, and (2) variability, which applies to fluctuations that are not explained by deterministic processes and does not decline asymptotically with sample size. Examples demonstrate how different sources of stochasticity impact inference and prediction and how allowance for stochastic influences can guide research.

Clark, J.S. 2012. The coherence problem with the Unified Neutral Theory of Biodiversity. Trends in Ecology and Evolution, 27:198-202.

Abstract
The Unified Neutral Theory of Biodiversity (UNTB), proposed as an alternative to niche theory, has been viewed as a theory that species coexist without niche differences, without fitness differences, or with equal probability of success. Support is claimed when models lacking species differences predict highly aggregated metrics, such as species abundance distributions (SADs) or species area distributions (SARs). Here, I summarize why UNTB generates confusion, and is not actually relevant to niche theory (i.e. an explanation for why and how many species coexist). Equal probability is not a theory, but lack of one; it does not include or exclude any process relevant to coexistence of competitors. Models lacking explicit species can make useful predictions, but this does not support neutral theory. I provide s suggestions that could help reduce confusion generated by the debate.

Clark, J.S. and M. H. Hersh. 2009. Inference when multiple pathogens affect multiple hosts: Bayesian model selection. Bayesian Analysis 4:337 - 366

Abstract
A large literature concerns the epidemiology of single pathogens on single hosts. Yet in some environmental applications, such as fungal pathogens of forest tree seedlings, the \one host-one pathogen" paradigm may not be applicable. Multiple potential pathogens are often found in a single individual and/or multiple hosts share the same pathogens. Understanding diversity requires techniques to infer how multiple pathogens might regulate multiple hosts and to predict how im- pacts might vary with the environment. Here we present a hierarchical framework for the case where there is detection information based on multiple sources (cul- tures, gene sequencing, and survival observations), and the inference problem in- cludes not only parameters that describe environmental in°uences on pathogen in- cidence, infection, and host survival, but also on latent states themselves{pathogen incidence at a site and infection statuses of hosts. Due to the large size of the model space, we develop a reversible jump Markov chain Monte Carlo approach to select models, estimate posterior distributions, and predict environmental in°uences on host survival. We demonstrate with application to a data set involving fungal pathogens on tree hosts, where data include host survival and fungal detection using cultures and DNA sequencing.

Clark, J.S., and Y. Ji. 1995. Fecundity and dispersal in plant populations: implications for structure and diversity. The American Naturalist. 146(1): 72-111.

Abstract
Demographic models of tree populations assume that seed availability does not depend on the populations themselves. We develop models to assess the consequences of fecundity and dispersal for populations structure and diversity. Results show that population structure and reproductive success are importantly affected by seed production and dispersal for realistic parameterization of time scales describing thinning, disturbance, maturation, and longevity. Maturation age affects mean and variance in seed rain. Populations with well-dispersed seed have a structure that is most sensitive to maturation age when disturbance is frequent. With restricted dispersal, delayed maturation means increased variability in seed rain, maximized when half of all patches support reproductive individuals. Density-dependent thinning compensates for the initial variability conferred by limited dispersal but not enough to permit the neglect of fecundity and dispersal at the disturbance frequencies and thinning rates typical in many forests. Longevity matters most when it is short and disturbance rare. To assess the effects of dispersal on reproductive success, we partition the contributions of seed-rain mean and variance. Fecundity and population structure affect both the mean and the variance in seed rain, albeit in different ways. Dispersal affects only the variance. The partitioned contribution of mean and variance are used to consider two cases: how dispersal consequences for reproductive success depend on life-history schedules and disturbance regime, and boundary growth rates of a globally dispersed population invading a resident population with restricted dispersal. In both cases, restricted dispersal has important consequences on the scales observed in many real forests. Most models of forest tree dynamics assume a globally dispersed seed pool that is disconnected from the populations that should produce that seed. This assumption leads to two opposing (offsetting?) consequences for species diversity: artificially high diversity due to continuous seed supply and artificially low diversity due to lack of sites where good competitors with restricted dispersal should be absent.

Clark, J.S., B. Beckage, P. Camill, B. Cleveland,J. Hille Ris Lambers, J. Lichter, J. McLachlan, J. Mohan, and P. Wyckoff. 1999. Interpreting Recruitment Limitation In Forests. American Journal of Botany. 86(1): 1-16.

Abstract
Studies of tree recruitment are many, but they provide few general insights into the role of recruitment imitation for population dynamics. That role depends on the vital rates (transitions) from seed production to sapling stages and on overall population growth. To determine the state of our understanding of recruitment limitation we examined how well we can estimate parameters corresponding to these vital rates. Our two-part analysis consists of (1) a survey of published literature to determine the spatial and temporal scale of sampling that is basis for parameter estimates, and (2) an analysis of extensive data sets to evaluate sampling intensity found in the literature. We find that published studies focus on fine spatial scales, emphasizing large numbers of small samples within a single stand, and tend not to sample multiple stands or variability across landscapes. Where multiple stands are sampled, sampling is often inconsistent. Sampling of seed rain, seed banks, and seedlings typically span <1 yr and rarely last 5 yr. Most studies of seeding establishment and growth consider effects of a single variable and a single life history stage. By examining how parameter estimates are affected by the spatial and temporal extent of sampling we find that few published studies are sufficiently extensive to capture the variability in recruitment stages. Early recruitment stages are especially variable and require samples across multiple years and multiple stands. Ironically, the longest duration data sets are used to estimate mortality rates, which are less variable (in time) than are early life history stages. Because variables that affect recruitment rates interact, studies of these interactions are needed to assess their full impacts. We conclude that greater attention to spatially extensive and longer duration sampling for early life history stages is needed to assess the role of recruitment limitation in forests.

Clark, J.S., B.D. Soltoff, A.S. Powell, and Q.D. Read. 2012. Evidence from individual inference for high-dimensional coexistence: long term experiments on recruitment response. PLoS One, 7 e30050. doi:10.1371/journal.pone.0030050.

Abstract
Background For competing species to coexist, individuals must compete more with others of the same species than with those of other species. Ecologists search for tradeoffs in how species might partition the environment. The negative correlations among competing species that would be indicative of tradeoffs are rarely observed. A recent analysis showed that evidence for partitioning the environment is available when responses are disaggregated to the individual scale, in terms of the covariance structure of responses to environmental variation. That study did not relate that variation to the variables to which individuals were responding. To understand how this pattern of variation is related to niche variables, we analyzed responses to canopy gaps, long viewed as a key variable responsible for species coexistence. Methodology/Principal Findings A longitudinal intervention analysis of individual responses to experimental canopy gaps with 12 yr of pre-treatment and 8 yr post-treatment responses showed that species-level responses are positively correlated – species that grow fast on average in the understory also grow fast on average in response to gap formation. In other words, there is no tradeoff. However, the joint distribution of individual responses to understory and gap showed a negative correlation – species having individuals that respond most to gaps when previously growing slowly also have individuals that respond least to gaps when previously growing rapidly (e.g., Morus rubra), and vice versa (e.g., Quercus prinus). Conclusions/Significance Because competition occurs at the individual scale, not the species scale, aggregated species-level parameters and correlations hide the species-level differences needed for coexistence. By disaggregating models to the scale at which the interaction occurs we show that individual variation provides insight for species differences.

Clark, J.S., B.J. Stocks., and P.J.H. Richard. 1996. Climate implications of biomass burning since the 19th century in eastern North America. Global Change Biology 2: 433-442.

Abstract
Recent predictions that tropospheric aerosols have counterbalanced greenhouse warming assume aerosol emissions were low before AD1850 and then increased dramatically with industrialization of the Northern Hemisphere and biomass burning in the Tropics. We assembled the lake sediment record of emissions across northeastern North America, where temperatures are predicted to have been substantially affected by industrial aerosols. Sediment evidence suggests a systematic shift in source and an overall decline in emissions since the 19th century. The geographical shift results from high presettlement emissions from wildfires in the Midwest that collapsed with tillage and fire suppression. Meanwhile, emissions were increasing in the North-east with European settlement. These regional changes produced a shift from the continental interior to the North-east. An overall decline results because decreases in the Midwest more than compensate for increases in the North-east. Results suggest the Central Plains as an important source of emissions in the recent past, consistent with pioneer accounts of dense smoke clouds emanating from prairie in the 19th century. Contrary to recent models that suggest increased 20th century combustion emissions could have offset warming effects of rising greenhouse gases, our data suggest that aerosols could have actually decreased over this interval. Although we cannot directly quantify aerosols from our methods, the emissions of large particles suggest assumptions of 20th century aerosol declines should be reconsidered.

Clark, J.S., C. Fastie, G. Hurtt, S.T. Jackson, C. Johnson, G.A. King, M. Lewis, J. Lynch, S. Pacala, C. Prentics, E.W. Schupp, T. Webb III, and P. Wyckoff. 1998. Reid's paradox of rapid plant migration: dispersal theory and interpretation of paleoecological records. Bioscience 48(1): 13-24.

Abstract
Biologists have long regarded the natural dispersal of large seeds as an impediment to plant range expansion after glacial periods. Global maps predicting biome distributions under future climate change scenarios are now prompting ecologists to think about the dispersal problem: If rapid climate change or habitat destruction remove sizable portions of a plant's range, will seed dispersal allow colonization of distant areas that may become favorable? Dispersal and population spread is a continuing theme of paleoecological research, and it has demonstrated empirical migration rates that are three orders of magnitude faster than Clement Reid's estimate.

Clark, J.S., D. Bell, C. Chu, B. Courbaud, M. Dietze, M. Hersh, J. HilleRisLambers, I. Ibanez, S. L. LaDeau, S. M. McMahon, C.J.E. Metcalf, J. Mohan, E. Moran, L. Pangle, S. Pearson, C. Salk, Z. Shen, D. Valle, and P. Wyckoff. 2010. High dimensional coexistence based on individual variation: a synthesis of evidence. Ecological Monographs, 80:569-608

Abstract
High biodiversity of forests is not predicted by traditional models, and evidence for tradeoffs those models require is limited. High dimensional regulation (e.g., N factors to regulate N species) has long been recognized as a possible alternative explanation, but it has not be been seriously pursued, because only a few limiting resources are evident for trees, and analysis of multiple interactions is challenging. We develop a hierarchical model that allows us to synthesize data from long-term, experimental data sets with processes that control growth, maturation, fecundity, and survival. We allow for uncertainty at all stages and variation among 26,000 individuals and over time, including 268,000 tree years, for dozens of tree species. We estimate population level parameters that apply at the species level and the interactions among latent states, i.e., the demographic rates for each individual, every year. The former show that the traditional tradeoffs used to explain diversity are not present. Demographic rates overlap among species, and they do not show trends consistent with maintenance of diversity by simple mechanisms (negative correlations and limiting similarity). However, estimates of latent states at the level of individuals and years demonstrate that species partition environmental variation. Correlations between responses to variation in time are high for individuals of the same species, but not for individuals of different species. We demonstrate that these relationships are pervasive, providing strong evidence that high dimensional regulation is critical for biodiversity regulation.

Clark, J.S., D. M Bell, M. Kwit, A. Powell, And K. Zhu. 2013. Dynamic inverse prediction and sensitivity analysis with high-dimensional responses: application to climate-change vulnerability of biodiversity. Journal of Biological, Environmental, and Agricultural Statistics, 18:376-404.

Abstract
Sensitivity analysis (SA) of environmental models is inefficient when there are large numbers of inputs and outputs and interactions cannot be directly linked to input variables. Traditional SA is based on coefficients relating the importance of an input to an output response, generating as many as one coefficient for each combination of model input and output. In many environmental models multiple outputs are part of an integrated response that should be considered synthetically, rather than by separate coefficients for each output. For example, there may be interactions between output variables that cannot be defined by standard interaction terms for input variables. We describe dynamic inverse prediction (DIP), a synthetic approach to SA that quantifies how inputs affect the combined (multivariate) output. We distinguish input interactions (specified as a traditional product of input variables) from output interactions (relationships between outputs not directly linked to inputs). Both contribute to traditional SA coefficients and DIP in ways that permit interpretation of unexpected model results. An application of broad and timely interest, anticipating effects of climate change on biodiversity, illustrates how DIP helps to quantify the important input variables and the role of interactions. Climate affects individual trees in competition with neighboring trees, but interest lies at the scale of species and landscapes. Responses of individuals to climate and competition for resources involve a number of output variables, such as birth rates, growth, and mortality. They are all components of ‘individual health’, and they interact in ways that cannot be linked to observed inputs, through allocation constraints.We show how prior dependence is introduced to aid interpretation of inputs in the context of ecological resource modeling. We further demonstrate that a new approach to multiplicity (multiple-testing) correction can be implemented in such models to filter through the large number of input combinations. DIP provides a synthetic index of important inputs, including climate vulnerability in the context of competition for light and soil moisture, based on the full (multivariate) response. By aggregating in specific ways (over individuals, years, and other input variables) we provide ways to summarize and rank species in terms of their vulnerability to climate change. This article has supplementary material online.

Clark, J.S., D. M. Bell, M. Kwit, A. Powell, R. Roper, A. Stine, B. Vierra, and K. Zhu. 2012. Individual-scale inference to anticipate climate-change vulnerability of biodiversity. Philosophical Transactions of the Royal Society B, 367, 236-246.

Abstract
Anticipating how biodiversity will respond to climate change is challenged by the fact that climate variables affect individuals in competition with others, but interest lies at the scale of species and landscapes. By omitting the individual scale, models cannot accommodate the processes that determine future biodiversity. We demonstrate how individual-scale inference can be applied to the problem of anticipating vulnerability of species to climate. The approach places climate vulnerability in the context of competition for light and soil moisture. Sensitivities to climate and competition interactions aggregated from the individual tree scale provide estimates of which species are vulnerable to which variables in different habitats. Vulnerability is explored in terms of specific demographic responses (growth, fecundity and survival) and in terms of the synthetic response (the combination of demographic rates), termed climate tracking. These indices quantify risks for individuals in the context of their competitive environments. However, by aggregating in specific ways (over individuals, years, and other input variables), we provide ways to summarize and rank species in terms of their risks from climate change.

Clark, J.S., D.M. Bell, M.C. Kwit, and K. Zhu. 2014. Competition-interaction landscapes for the joint response of forests to climate change. Global Change Biology, 20, 1979-1991.

Abstract
The recent global increase in forest mortality episodes could not have been predicted from current vegetation models that are calibrated to regional climate data. Physiological studies show that mortality results from interactions between climate and competition at the individual scale. Models of forest response to climate do not include interactions because they are hard to estimate and require long-term observations on individual trees obtained at frequent (annual) intervals. Interactions involve multiple tree responses that can only be quantified if these responses are estimated as a joint distribution. A new approach provides estimates of climate–competition interactions in two critical ways, (i) among individuals, as a joint distribution of responses to combinations of inputs, such as resources and climate, and (ii) within individuals, due to allocation requirements that control outputs, such as demographic rates. Application to 20 years of data from climate and competition gradients shows that interactions control forest responses, and their omission from models leads to inaccurate predictions. Species most vulnerable to increasing aridity are not those that show the largest growth response to precipitation, but rather depend on interactions with the local resource environment. This first assessment of regional species vulnerability that is based on the scale at which climate operates, individual trees competing for carbon and water, supports predictions of potential savannification in the southeastern US.

Clark, J.S., D.M. Bell, M.H. Hersh, and L. Nichols. 2011. Climate change vulnerability of forest biodiversity: climate and resource tracking of demographic rates. Global Change Biology, 17, 1834-1849.

Abstract
Forest responses to climate change will depend on demographic impacts in the context of competition. Current models used to predict species responses, termed climate envelope models (CEMs), are controversial, because (i) calibration and prediction are based on correlations in space (CIS) between species abundance and climate, rather than responses to climate change over time (COT), and (ii) they omit competition. To determine the relative importance of COT, CIS, and competition for light, we applied a longitudinal analysis of 27 000 individual trees over 6–18 years subjected to experimental and natural variation in risk factors. Sensitivities and climate and resource tracking identify which species are vulnerable to these risk factors and in what ways. Results show that responses to COT differ from those predicted based on CIS. The most important impact is the effect of spring temperature on fecundity, rather than any input variable on growth or survival. Of secondary importance is growing season moisture. Species in the genera Pinus, Ulmus, Magnolia, and Fagus are particularly vulnerable to climate variation. However, the effect of competition on growth and mortality risk exceeds the effects of climate variation in space or time for most species. Because sensitivities to COT and competition are larger than CIS, current models miss the most important effects. By directly comparing sensitivity to climate in time and space, together with competition, the approach identifies which species are sensitive to climate change and why, including the heretofore overlooked impact on fecundity.

Clark, J.S., D.M. Bell, M.H. Hersh, M. Kwit, E. Moran, C. Salk, A. Stine, D. Valle, and K. Zhu. 2011. Individual-scale variation, species-scale differences: inference needed to understand diversity. Ecology Letters 14, 1273-1287.

Abstract
As ecological data are usually analysed at a scale different from the one at which the process of interest operates, interpretations can be confusing and controversial. For example, hypothesised differences between species do not operate at the species level, but concern individuals responding to environmental variation, including competition with neighbours. Aggregated data from many individuals subject to spatio-temporal variation are used to produce species-level averages, which marginalise away the relevant (process-level) scale. Paradoxically, the higher the dimensionality, the more ways there are to differ, yet the more species appear the same. The aggregate becomes increasingly irrelevant and misleading. Standard analyses can make species look the same, reverse species rankings along niche axes, make the surprising prediction that a species decreases in abundance when a competitor is removed from a model, or simply preclude parameter estimation. Aggregation explains why niche differences hidden at the species level become apparent upon disaggregation to the individual level, why models suggest that individual-level variation has a minor impact on diversity when disaggregation shows it to be important, and why literature-based synthesis can be unfruitful. We show how to identify when aggregation is the problem, where it has caused controversy, and propose three ways to address it.

Clark, J.S., E. Macklin, and L. Wood. 1998. Stages and spatial scales of recruitment limitation in Southern Appalachian forests. Ecological Monographs. 68(2): 213-235.

Abstract
Recruitment limitation of tree population dynamics is poorly understood, because fecundity and dispersal are difficult to characterize in closed stands. We present an approach that estimates seed production and dispersal under closed canopies and four limitations on recruitment: tree density and location, fencundity, seed dispersal, and establishment. Consistent estimates are obtained for 14 canopy species using 5 yr. of census data from 100 seed traps and several thousand mapped trees and seedlings from five southern Appalachian forest stands that span gradients in elevation and moisture. Fecundity ranged over four orders of magnitude, from 10+ cm2 basal area/yr to > 103 cm2/yr. Mean dispersal distance ranged from <5 m to >20 m and was positively correlated with fecundity. Species also differ in the degree of seed clumping at find (1 m2) spatial scales. Dispersal patterns can be classed in two groups based on dispersal vector: wind-dispersed taxa with high fecundities, long-distance dispersal, and low clumping vs. animal-dispersal taxa with low fecundities, short-distance dispersal, and a high degree of clumping. Colonization limitations caused by sizes and locations of parent trees, fecundity, and dispersal were quantified as the fraction of sites receiving seed relative to that expected under null models that assume dispersal is nonlocal and not clumped. Difference among species in colonization levels ranged from those capable of saturating the forest floor with seed in most stands to ones that leave much of the forest floor without seed, despite presence of adults. Seedling establishment is one of the strongest filters on recruitment in our study area. Taken together, our results indicate (1) that fecundity and dispersal can be resolved, even under a closed canopy, and (2) that recruitment of many species is limited by the density and location of source, dispersal patterns, or both.

Clark, J.S., J. Mohan, M. Dietze, I. Ibanez. 2003. Coexistence: How to identify trophic trade-offs. Ecology. 84(1): 17-31.

Abstract
Analyses of growth response to resource availability are the basis for interpreting whether trophic trade-offs contributes to diversity. If different species respond most to resources that are limiting at different times, then those differences may trade off with other trophic or life-history traits that, together, help to maintain diversity. The statistical models used to infer trophic differences do not accommodate uncertainty in resources and variability in how individuals use resources. We provide hierarchical models for resource-growth responses that accommodate stochasticity in parameters and in data, despite the fact causes are typically unknown. A complex joint posterior distribution taken over >102 parameters is redily integrated to provide a comprehensive accounting of uncertainty in the growth response, together with a small number of hyperparameters that summarize the population response. An application involving seedling growth response to light availability shows that large trophic differences among species suggested by traditional models can be an artifact of the assumption that all individuals respond identically. The hierarchical analysis indicates broad trophic overlap, with the implication that slow dynamics play a more important role in preserving diversity than is widely believed.

Clark, J.S., M. Dietze, S. Chakraborty, P.K. Agarwal, I. Ibanez, S. LaDeau, and M. Wolosin. 2007. Resolving the biodiversity paradox. Ecology. 10: 647-662.

Abstract
The paradox of biodiversity involves three elements, (i) mathematical models predict that species must differ in specific ways in order to coexist as stable ecological communities, (ii) such differences are difficult to identify, yet (iii) there is widespread evidence of stability in natural communities. Debate has centred on two views. The first explanation involves tradeoffs along a small number of axes, including 'colonization-competition', resource competition (light, water, nitrogen for plants, including the 'successional niche'), and life history (e.g. high-light growth vs. low-light survival and few large vs. many small seeds). The second view is neutrality, which assumes that species differences do not contribute to dynamics. Clark et. al. (2004) presented a third explanation, that coexistence is inherently high dimensional, but still depends on species differences. We demonstrate that neither traditional low-dimensional tradeoffs nor neutrality can resolve the biodiversity paradox, in part by showing that they do not properly interpret stochasticity in statistical and in theoretical models.

Clark, J.S., M. Lewis, and L. Horvath. 2001. Invasion by extremes: Population spread with variation in dispersal and reproduction. The American Naturalist. 157(5): 537-554.

Abstract
For populations having dispersal described by fat-tailed kernels (kernels with tails that are not exponentially bounded), asymptotic population spread rates cannot be estimated by traditional models because these models predict continually accelerating (asymptotically infinite) invasion. The impossible predictions come from the fact that the fat-tailed kernels fitted to dispersal data have a quality (nondiscrete individuals and, thus, no moment-generating function) that never applies to data. Real organisms produce finite (and random) numbers of offspring; thus, an empirical moment-generating function can always be determined. Using an alternative method to estimate spread rates in terms ofextreme dispersal events, we show that finite estimates can be derived for fat-tailed kernels, and we demonstrate how variable reproduction modifies these rates. Whereas the traditional models define spread rate as the speed of anindividuals, our alternative definition for spread rate is the expected velocity for the location of the furthest-forward individual in the population. The asymptotic wave speed for a constant net reproductive rate R-0 is approximated as (1/T)(pi uR(0)/2)1/2 m yr-1, where T is generation time, and u is a distance parameter (m2) of Clark et al. s 2Dt model having shape parameter. From fitted dispersal kernels with fat tails p = 1 and infinite variance, we derive finite rates of spread and a simple method for numerical estimation. Fitted kernels, with infinite variance, yield distributions of rates of spread that are asymptotically normal and, thus, have finite moments. Variable reproduction can profoundly affect rates of spread. By incorporating the variance in reproduction that results from variable life span, we estimate much lower rates than predicted by the standard approach, which assumes a constant net reproductive rate. Using basic life-history data for trees, we show these estimated rates to be lower than expected from previous analytical models and as interpreted from paleorecords of forest spread at the end of the Pleistocene. Our results suggest reexamination of past rates of spread and the potential for future response to climate change.

Clark, J.S., M. Silman, R. Kern, E. Macklin, and J. Hille Ris Lambers. 1999. Seed Dispersal Near And Far: Patterns Across Temperate And Tropical Forests. Ecology. 80(5): 1475-1494.

Abstract
Dispersal affects community dynamics and vegetation response to global change. Understanding these effects requires descriptions of dispersal at local and regional scales and statistical models that permit estimation. Classical models of dispersal describe local or long-distance dispersal, but not both. The lack of statistical methods means that models have rarely been fitted to seed dispersal in closed forests. We present a mixture model of dispersal that assumes a range of dispersal patterns, both local and long distance. The bivariate Student's t or "2Dt" follows from an assumption that the distance parameter in a Gaussian model varies randomly, thus having a density of its own. We use an inverse approach to "compete" our mixture model against classical alternatives; using seed rain databases from temperate broadleaf, temperate mixed-conifer, and tropical floodplain forests. For most species, the 2Dt model fits dispersal data better than do classical models. The superior fit results from the potential for a convex shape near the source tree and a "fat tail." Our parameter estimates have implications for community dynamics at local scales, for vegetation responses to global change at regional scales, and for differences in seed dispersal among biomes. The 2Dt modelpredicts that less seed travels beyond the immediate crown influence (<5m) than is predicted under a Gaussian model, but that more seed travels longer distances (>30 m). Although Gaussian and exponential models predict slow population spread in the face of environmental change, our dispersal estimates suggest rapid spread. The preponderance of animal-dispersed and rare seed types in tropical forests results in noisier patterns of dispersal than occur in temperate hardwood and conifer stands.

Clark, J.S., M. Wolosin, M. Dietze, I. Ibanez, S. LaDeau, M. Welsh, and B. Kloeppel. 2007. Tree growth inference and prediction from diameter censuses and ring widths. Ecological Applications 17(7): 1942-1953.

Abstract
Estimation of tree growth is based on sparse observations of tree diameter, ring widths, or increments read from a dendrometer. From annual measurements on a few trees (e.g., increment cores) or sporadic measurements from many trees (e.g., diameter censuses on mapped plots), relationships with resources, tree size, and climate are extrapolated to whole stands. There has been no way to formally integrate different types of data and problems of estimation that result from (1) multiple sources of observation error, which frequently result in impossible estimates of negative growth, (2) the fact that data are typically sparse (a few trees or a few years), whereas inference is needed broadly (many trees over many years), (3) the fact that some unknown fraction of the variance is shared across the population, and (4) the fact that growth rates of trees within competing stands are not independent. We develop a hierarchical Bayes state space model for tree growth that addresses all of these challenges, allowing for formal inference that is consistent with the available data and the assumption that growth is nonnegative. Prediction follows directly, incorporating the full uncertainty from inference with scenarios for ‘‘filling the gaps’’ for past growth rates and for future conditions affecting growth. An example involving multiple species and multiple stands with tree-ring data and up to 14 years of tree census data illustrates how different levels of information at the tree and stand level contribute to inference and prediction.

Clark, J.S., P. Agarwal , D.M. Bell , P. Flikkema , A. Gelfand , X. Nguyen , E. Ward , and J. Yang. 2011. Inferential ecosystem models, from network data to prediction. Ecological Applications, 21,1523-1536.

Abstract
Recent developments suggest that predictive modeling could begin to play a larger role not only for data analysis, but also for data collection. We address the example of efficient wireless sensor networks, where inferential ecosystem models can be used to weigh the value of an observation against the cost of data collection. Transmission costs make observations “expensive”; networks will typically be deployed in remote locations without access to infrastructure (e.g., power). The capacity to sample intensively makes sensor networks valuable, but high-frequency data are informative only at specific times and locations. Sampling intervals will range from meters and seconds to landscapes and years, depending on the process, the current states of the system, the uncertainty about those states, and the perceived potential for rapid change. Given that intensive sampling is sometimes critical, but more often wasteful, how do we develop tools to control the measurement and transmission processes? We address the potential of data collection controlled and/or supplemented by inferential ecosystem models. In a given model, the value of an observation can be evaluated in terms of its contribution to estimates of state variables and important parameters. There will be more than one model applied to network data that will include as state variables water, carbon, energy balance, biogeochemistry, tree ecophysiology, and forest demographic processes. The value of an observation will depend on the application. Inference is needed to weigh the contributions against transmission cost. Network control must be dynamic and driven by models capable of learning about both the environment and the network. We discuss application of Bayesian inference to model data from a developing sensor network as a basis for controlling the measurement and transmission processes. Our examples involve soil moisture and sap flux, but we discuss broader application of the approach, including its implications for network design.

Clark, J.S., S. LaDeau, and I. Ibanez. 2004. Fecundity of trees and the colonization-competition hypothesis. Ecological Monographs. 74(3): 415-442.

Abstract
Colonizationvcompetition trade-offs represent a stabilizing mechanism that is thought to maintain diversity of forest trees. If so, then early-successional species should benefit from high capacity to colonize new sites, and late-successional species should be good competitors. Tests of this hypothesis in forests have been precluded by an inability to estimate the many factors that contribute to seed production and dispersal, particularly the many types of stochasticity that contribute to fecundity data. We develop a hierarchical Bayes modeling structure, and we use it to estimate fecundity schedules from the two types of data that ecologists typically collect, including seed-trap counts and observations of tree status. The posterior density is obtained using Markov-chain Monte Carlo techniques. The flexible structure yields estimates of size and covariate effects on seed production, variability associated with population heterogeneity, and interannual stochasticity (variability and serial autocorrelation), sex ratio, and dispersal. It admits the errors in data associated with the ability to accurately recognize tree status and process misspecification. We estimate year-by-year seed-production rates for all individuals in each of nine sample stands from two regions and up to 11 yeaces among species and relationships among individuals allows evaluation of a number of hypotheses related to masting, effective population sizes, and location and covariate effects. It demonstrates large bias in previous methods. We focus on implications for colonizationvcompetition and a related hypothesis, the successional niche+trade-offs in the capacity to exploit high resource availability in early successional environments vs. the capacity to survive low resource conditions late in succession. Contrary to predictions of trade-off hypotheses, we find no relationship between successional status and fecundity, dispersal, or expected arrivals at distant sites. Results suggest a mechanism for maintenance of diversity that may be more general than colonizationv competition and successional niches. High variability and strong individual effects (variability within populations) generate massive stochasticity in recruitment that, when combined with ¬¬storage,¼¼ may provide a stabilizing mechanism. The storage effect stabilizes diversity when species differences ensure that responses estimation.

Clark, J.S., S.R. Carpenter, M. Barber, S. Collins, A. Dobson, J.A. Foley, D.M. Lodge, M. Pascual, R. Pielke Jr., W. Pizer, C. Pringle, and W. Reid. 2001. Ecological Forecasts: An Emerging Imperative. Science. 293: 657-660.

Abstract
Planning and decision-making can be improved by access to reliable forecasts of ecosystem state, ecosystem services, and natural capital. Availability of new data sets, together with progress in computation and statistics, will increase our ability to forecast ecosystem change. An agenda that would lead toward a capacity to produce, evaluate, and communicate forecasts of critical ecosystem services requires a process that engages scientists and decision-makers. Interdisciplinary linkages are necessary because of the climate and societal controls on ecosystems, the feedbacks involving social change, and the decision-making relevance of forecasts.

Clark, James S. 2010. Individuals and the Variation Needed for High Species Diversity in Forest Trees. Science, 327: 1129-1132.

Abstract
In the past, explanations for high species diversity have been sought at the species level. Theory shows that coexistence requires substantial differences between species, but species-level data rarely provide evidence for such differences. Using data from forests in the southeastern United States, I show here that variation evident at the individual level provides for coexistence of large numbers of competitors. Variation among individuals within populations allows species to differ in their distributions of responses to the environment, despite the fact that the populations to which they belong do not differ, on average. Results are consistent with theory predicting that coexistence depends on competition being stronger within than between species, shown here by analysis of individual-level responses to environmental fluctuation.

Clark, James S., David M. Bell, Matthew Kwit, A., Anne Stine, Ben Vierra, and Kai Zhu. 2012. Individual scale inference to anticipate climate change vulnerability of biodiversity. Philosophical Transactions of the Royal Society B 367:236-246.

Abstract
Anticipating how biodiversity will respond to climate change is challenged by the fact that climate variables affect individuals in competition with others, but interest lies at the scale of species and landscapes. By omitting the individual scale, models cannot accommodate the processes that determine future biodiversity. We demonstrate how individual-scale inference can be applied to the problem of anticipating vulnerability of species to climate. The approach places climate vulnerability in the context of competition for light and soil moisture. Sensitivities to climate and competition interactions aggregated from the individual tree scale provide estimates of which species are vulnerable to which variables in different habitats. Vulnerability is explored in terms of specific demographic responses (growth, fecundity and survival) and in terms of the synthetic response (the combination of demographic rates), termed climate tracking. These indices quantify risks for individuals in the context of their competitive environments. However, by aggregating in specific ways (over individuals, years, and other input variables), we provide ways to summarize and rank species in terms of their risks from climate change.

Clinton B, Maier C, Ford C, Mitchell R. 2011. Transient changes in transpiration, and stem and soil CO2 efflux in longleaf pine (Pinus palustris Mill.) following fire-induced leaf area reduction. Trees - Structure and Function1-11. doi:10.1007/s00468-011-0574-6

Abstract
In 20-year-old longleaf pine, we examined short-term effects of reduced live leaf area (AL) via canopy scorching on sap flow (Q; kg H2O h-1), transpiration per unit leaf area (EL; mm day-1), stem CO2 efflux (Rstem; lmol m-2 s-1) and soil CO2 efflux (Rsoil; lmol m-2 s-1) over a 2-week period during early summer. Rstem and Q were measured at two positions (1.3-m or BH, and base of live crown—BLC), and Rsoil was measured using 15 opensystem chambers on each plot. EL before and after treatment was estimated using Q measured at BLC with estimates of AL before and after scorching. We expected Q to decrease in scorched trees compared with controls resulting from reduced AL. We expected Rstem at BLC and BH and Rsoil to decrease following scorching due to reduced leaf area, which would decrease carbon supply to the stem and roots. Scorching reduced AL by 77%. Prior to scorching, Q at BH was similar between scorch and control trees. Following scorching, Q was not different between control and scorch trees; however, EL increased immediately following scorching by 3.5-fold compared to control trees. Changes in EL in scorched trees corresponded well with changes in VPD (D), whereas control trees appeared more decoupled

Clinton, B. D., J. M. Vose, J. D. Knoepp, K. J. Elliott, B. C. Reynolds, and S. J. Zarnoch. 2010. Can structural and functional characteristics be used to identify riparian zone width in southern Appalachian headwater catchments?. Canadian Journal of Forest Research, 40: 235-353.

Abstract
We characterized structural and functional attributes along hillslope gradients in headwater catchments. We endeavored to identify parameters that described significant transitions along the hillslope. On each of four catchments, we installed eight 50 m transects perpendicular to the stream. Structural attributes included woody and herbaceous vegetation; woody debris and forest floor mass, nitrogen (N) and carbon (C); total soil C and N; litterfall amount and quality by species; and microclimatic conditions. Functional attributes included litter decomposition, soil microarthropods, soil CO2 evolution, soil solution chemistry, and soil extractable N. Forest floor mass, N and C, and soil depth increased with distance from the stream and transitioned between 10 and 20 m. In contrast, litterfall N rate (kilograms of nitrogen per hectare per day), downed woody debris, soil A-horizon C and N, and soil solution NO3 concentration all decreased with distance, and exhibited significant transitions. Certain overstory species were more adundant in the uplands than near the stream. Herbaceous diversity and richness were similar across the hillslope, but species distributions varied in response to hillslope moisture content. Taken together, these results suggest that at 10-20 m from the stream, transitions occur that separate riparian from upland conditions and may provide valuable insight into riparian zone definition.

Clinton, B., J.J. Vose, and W.T. Swank. 1993. Site preparation burning to improve southern Appalachian pine-hardwood stands: vegetation composition and diversity of 13-year-old stands. Canadian Jounal of Forest Research 23: 2271-2277.

Abstract
Stand conversion through cutting and burning, and planting of Pinus strobus L., in low quality , mixed pine/hardwood ecosystems containing a Kalmia latifolia L. dominated understory, is a common prescription on xeric southern Appalachian forest sites. Four 13-year-old stands were examined for the effects of this treatment on early vegetation composition and diversity. Two of these stands were mechanically released at age 6. Density and basal area were estimated for understory and overstory components and density and % cover for their herb component. Species diversity (Shannon-Wiener Index) was estimated, and comparisons were made between layers, sites, and treatments (release vs. non- release). Diversity estimates were 3.19, 1.74, and 2.45 for the herb, shrub, and overstory layers, respectively, across all site treatments. For perspective, comparisons were made with a reference stand typical of stands receiving site preparation burning in the southern Appalachians. Overstory and herb diversity estimates were significantly lower for the reference stand compared to the same layers in the 13-year-old stands.

Clinton, B., L.R. Boring. 1993. Characteristics of canopy gaps and drought influences in oak forests of the Coweeta Basin. Ecology 74(5): 1551-1558.

Abstract
Canopy gaps in southern Appalachian mixed-Quercus forests were characterized to assess the impact of the 1985-88 record drought on patterns of tree mortality. Among 1-5 year old gaps, the most comon gap type as the 1-yr-old single tree snag, accounting for 49% of all gaps sampled; 65% of all gaps occurred within 2 yr of the drought peak. Gap area ranged from 40 to 850 m^2, averaged 239 m^2, with a median of 152 m^2. Rates of gap formation were 0.8 gaps/ha^-1/yr^-1 affecting 2.0% of the area in the Quercus forest type in 1988. The most frequent gap-forming species were red oak. Evidence suggests that moisture stress brought on by severe drought increases the susceptibility of Quercus species to the shoe- string fungus Armillaria mellea.

Clinton, B.D, J.M. Vose, J.D. Knoepp, K.J. Elliott, and B. Reynolds. 2010. Riparian area structure and function in the southern Appalachian headwater streams. Canadian Journal of Forest Research 40(2): 235-253.

Abstract
We characterized structural and functional attributes along hillslope gradients in headwater catchments. We endeavored to identify parameters that described significant transitions along the hillslope. On each of four catchments, we installed eight 50 m transects perpendicular to the stream. Structural attributes included woody and herbaceous vegetation; woody debris and forest floor mass, nitrogen (N) and carbon (C); total soil C and N; litterfall amount and quality by speciesl and microclimate conditions. Functional attributes included litter decomposition, soil microarthropods, soil CO2 evolution, soil solution chemistry, and soil extractable N. Forest floor mass, N and C, and soil depth increased with distance from the stream and transitioned between 10 and 20 m. In contrast, litterfall N rate (kilograms of nitrogen per hectare per day), downed woody debris, soil A-horizon C and N, and soil solution N03 concentration all decreased with distance, and exhibited significant transactions. Certain overstory species were more abundant in the uplands than near the stream. Herbaceous diversity and richness were similar across the hillslope, but species distributions varied in response to hillslope moisture content. Taken together, these results suggest that at 10-20 m from the stream, transitions occur that separate riparian from upland conditions and may provide valuable insight into riparian zone definition.

Clinton, B.D, K.J. Elliott, and W.T. Swank. 1997. Response of planted eastern white pine (Pinus strobus L.) to mechanical release, competition, and drought in the Southern Appalachians. Southern Journal of Applied Forestry. 21(1): 19-23.

Abstract
Conversion of low-quality, natural mixed pine/hardwood ecosystems, containing a mountain laurel dominated understory, to more productive eastern white pine/mixed hardwood systems is a common prescription on relatively xeric southern Appalachian forest sites. We examined the effects of mechanical release, interspecific competition, and annual precipitation on growth of planted white pine in four 14-yr-old stands in the southern Appalachians. Two stands were mechanically released at age 6. No significant differences in biomass, basal area, or diameter were found between treatments for all species combined. Radial increment was significantly less during a drought year for both treatments. Height increment was less sensitive to severe moisture limitation than radial increment. Height and radial increment were compared to distance-dependent and distance-independent measures of competition for the nonreleased stands. Indices based on height and height/distance explained the greatest amount of variation in both radial and height increment. The influence of post-release severe drought may have delayed or diminished the response to release. The competitive influence of understory dominant mountain laurel at stand age 14 appears to be slight compared to the influence of other competing hardwood vegetation.

Clinton, B.D. 2003. Light, temperature, and soil moisture responses to elevation, evergreen understory, and small canopy gaps in the southern Appalachians. Forest Ecology and Management. 186(1-3): 243-255.

Abstract
Small canopy openings often alter understory microclimate, leading to changes in forest structure and composition. It is generally accepted that physical changes in the understory (i.e., microclimatic) due to canopy removal drive changes in basic forest processes, particularly seedling recruitment which is intrinsically linked to soil moisture availability, light and, to a lesser extent, temperature. We examined the impact of small canopy gaps of the type (snags) and size (~300 m2) most frequently observed in the southern Appalachians on the understory microclimate. We created artificial canopy gaps at two elevations (a.m.s.l.) by girdling trees in areas with and without a Rhododendron maximum L. (rosebay rhododendron) understory. Soil and air temperature (+C), photosynthetically active radiation (PAR; +mol m-2 s-1), and volumetric soil water content (%WC) in the upper 15 cm of soil were measured along transects generally running north to south through each gap. Overall, PAR was substantially less in rhododendron gaps than in non-rhododendron gaps. We found a slight increase in PAR in non-rhododendron gaps during spring and summer compared to controls. Very little seasonal variation in PAR was observed in rhododendron gaps compared with non-rhododendron gaps. In general, %WC in rhododendron gaps was lower than in non-rhododendron gaps and less variable. We also found a gap response in incident PAR during the spring and summer seasons. There was no significant effect of gap creation on %WC, nor were there site (elevation) differences or effects due to the presence of rhododendron. Further, there was no significant gap effect on mean, maximum, or minimum soil and air temperature; however, there were significant effects from the presence of rhododendron and between sites for PAR and soil and air temperature during certain seasons of the year. Although there is some certainty about measurable responses in key microclimatic variables in rhododendron and non-rhododendron gaps found in this study, we could not be certain if responses represent a significant enough departure from values in undisturbed conditions to elicit a tree recruitment response. Our results indicate that for openings of the size examined here, topography and evergreen understory are the primary determinants of spatial and temporal heterogeneity in understory microclimate. Published by Elsevier B.V.

Clinton, B.D., and C.R. Baker. 2000. Catastrophic windthrow in the southern Appalachians: characteristics of pits and mounds and initial vegetation responses. Elsevier: Forest Ecology and Management. 126: 51-60.

Abstract
We characterized pit and mound (PM) topography resulting from catastrophic wind in the Coweeta Basin, and located 48 PMs across a variety of forest types. Our measurements included pit length, width, and depth: and mound height, thickness, and width. Species of fallen trees were identified, and DBH (diameter at breast height 1.37 m) was measured for biomass determination. We identified five distinct microsites at each PM: mound face, mound top, pit bottom, pit-wall, and intact forest floor. On each microsite, we measured photosynthetically active radiation (PAR), soil temperature, and soil moisture, and took soil samples from four microsites (intact forest floor, pit wall, pit bottom, mound top) to determine carbon and nitrogen concentrations. Treefall direction was marginally non-random. Three PM dimensions were significantly related to fallen tree biomass; mound width; mound height; and pit width. Other relationships failed because (1) rooting depth of the fallen tree was not necessarily proportional to tree size; and (2) trees that fell striking other trees often slid back into the pit, altering its dimensions. PAR was highest at mound top (250 +mol mˉ+ s ˉ+) and lowest in pit bottom (70 +mol mˉ+s ˉ+). Mean soil temperature varied ≈3+C across mircosites, and soil moisture ranged from 24% on the mound top and mound face to 34% in the pit bottom. Nitrogen and carbon concentrations were significantly higher on the forest floor ([N] =0.23%; [C] = 4.73%) than on the other three mircosites ([N] = 0.08-0.10%; [C] = 1.4-2.2%). Overtime, soil nutrition and microsite instability, due to erosion and settling, may be the most influential factors determining rates of vegetative establishment in PMs. We characterized initial vegetative recovery in 27 blowdown sites. Trees were placed in one of two damage classes; direct wind damage (direct); and damage due to the fall of another tree (indirect). Basal and/or bole sprouting, and live or dead crowns were noted. Blowdown areas ranged from 181 to 4043 m+ and averaged 1175 m+. Mean diameter of indirectly damaged trees was 50% of the mean for trees directly damaged, but both had similar minimum diameters. Overall, the biomass of indirectly damaged trees accounted for <10% of total biomass but 33% of the total number of stems. Of the indirectly damaged trees, 38% were topped, 82% exhibited basal or bole sprouting, and 21% had live crowns. By contrast, of the directly damaged trees, only 5% were topped, <50% were sprouting, and only 11% had live crowns.

Clinton, B.D., and J.M. Vose. 1996. Effects of Rhododendron maximum L. on Acer rubrum L. seedling establishment. Castanea. 61(1): 38-45.

Abstract
Rhododendron maximum L. restricts regeneration of overstory species; however, the mechanisms are poorly understood. Three treatments were used to examine the effects of R. maximum germination success and survival of Acer rubrum L. under a closed overstory canopy: (1) R. maximum understory, (2) open understory, and (3) open understory with shadecloth. Shadecloth treatments mimicked the low light conditions beneath R. maximum while controlling for R. maximum forest floor influences. Soil moisture was significantly lower under R. maximum than under open or shadecloth treatments. Initially, Acer rubrum survival was similar for open understory and shadecloth treatments, while germination and survival in R. maximum plots were low. After approximately 20 d, mortality in the shadecloth treatment increased and survival rates were less than 5% by the end of the sampling period. Survival in the open understory treatment stabilized at >2X that observed under shadecloth, while percent germination and survival in R. maximum plots were lower than in either of the other treatments throughout the sampling period. These results suggest that in addition to the light limitation associated with R. maximum, edaphic effects such as low soil moisture or allelopathic compounds may inhibit Acer rubrum success.

Clinton, B.D., and J.M. Vose. 1999. Fine root respiration in mature eastern white pine (Pinus strobus) in situ: the importance of CO2 in controlled environments. Tree Physiology. 19: 475-479.

Abstract
We measured seasonal fine root respiration rate in situ while controlling chamber temperature and [CO2]. Atmospheric [CO2] ([CO2]a) and measured soil [CO2] ([CO2]s) were alternately delivered to a cuvette containing intact fine roots of eastern white pine (Pinus strobus L.). Respiration rates were consistently higher in [CO2]a than in [CO2]s and were almost three times higher during midsummer. Respiration rates were immediately reversed after returning to the alternate [CO2] (i.e., [CO2]a a [CO2]s a [CO2]a, and vice versa) suggesting a direct effect of elevated [CO2] on apparent respiration. Soil [CO2]-based respiration rates decreased with increasing [CO2] on a dry mass and tissue [N] basis. We conclude that estimates of soil CO2 flux and soil carbon budgets may be improved by more completely accounting for the rhizosphere microclimate (i.e., soil temperature and [CO2]s) during measurement of fine root respiration.

Clinton, B.D., and J.M. Vose. 2003. Differences in Surface Water Quality Draining Four Road Surface Types in the Southern Appalachians. Southern Journal of Applied Forestry. 27(2): 100-106.

Abstract
Improved and unimproved roads can be the primary source of stream sediment in forested watersheds. We assessed differences in production of total suspended solids (TSS; ppm) from four road surface conditions in a Southern Appalachian watershed: (1) a 2-yr-oldpaved surface (P), (2) an improved gravel surface with controlled drainage and routine maintenance (RG), (3) an improved gravel surface with erosion and sediment control structures installed and routine maintenance (IG), and (4) an unimproved poorly maintained gravel surface (UG). Variation was high among and within road surface types. The P surface generated the least amount of TSS, which was comparable to control sites, while the UG surface generated the most. The P surface produced significantly less TSS than the UG surface, but not less than the IG andRG surfaces. Variation among road surface types was related to TSS travel distance below the road, precipitation amount, time of year, and the existence of functioning erosion and sediment control structures. TSS decreased with travel distance (P=-81 % over 38.5 m, IG =-30% over 30.5 m, RG=-89% over 39.4 m, and UG=-22% over 28.1 m). Also in this study we assessed the delivery of total petroleum hydrocarbons (TPH; ppm) from the P surface and found concentrations of< 0.5 ppm, which are well below published USEPA andNCDENR TPH standards for sediment. Paving is an attractive option for reducing maintenance costs and sediment production and transport; however, levels of TPH from freshly applied asphalt are unknown. South. J. Appl. For. 27(2): 100-106.

Clinton, B.D., and J.M. Vose. 2006. Variation in stream water quality in an urban headwater stream in the southern Appalachians. Water, Air, and Soil Pollution. 169: 331-353.

Abstract
We examined the influence of a forested landscape on the quality of water in a stream originating on an urban landscape and flowing through National Forest lands. Sample sites included an urban stream (URB), a site on the same stream but within a National Forest (FOR) and 2 km downstream from the URB site, and a small, undisturbed, forested reference tributary of the main stream (REF). We monitored stream water quality from March 2002 through June 2003. Average base flows for the three stream sites were URB = 184 L s?1, FOR = 420 L s?1, and REF = 17 L s?1. We analyzed weekly stream water samples for NO?3 , NH+4 , PO+4 , Cl?, K, Ca, Mg, SO4, SiO2, pH, conductivity, total suspended solids (TSS), and bacteria on a monthly basis. Most solutes were higher in concentration at the URB site, as were conductivity, TSS, and bacteria counts. Reductions in NO?3 , NH+4 , and PO+4 concentrations between the URB and FOR sites were inferred from changes in nutrient: chloride ratios. Bacteria populations were greater and more responsive to stream temperature at the URB site. Water quality responses to changes in stream discharge varied among sites but were greater at the URB site. By all measures, water quality was consistently higher at the FOR site than at the URB site.

Clinton, B.D., and L.R. Boring. 1993. Canopy gap characteristics and drought influences in oak forests of the Coweeta basin. Ecology. 74(5): 1551-1558.

Abstract
Canopy gaps in southern Appalachian mixed-Quercus forests were characterized to assess the impact of the 1985-1988 record drought on patterns of tree mortality in relation to topographic variables and changes in overstory composition. Using permanent transects, we sampled 68 canopy gaps within the Coweeta Basin. Among 1-5 yr old gaps, the most common gap type was the 1-yr-old single-tree snag, accounting for 49% of all gaps sampled; 65% of all gaps occurred within 2 yr of the drought peak. Gap area ranged from 40 to 850 m2, averaged 239 m2, with a median of 152 m2. Analysis of 1988 color infrared (IR) aerial imagery yielded a gap formation rate of 0.8 gaps-ha~' -yr~' in mixed-Quercus stands affecting 2.0% of the area in this forest type in 1988. The most frequent gap-forming species were Quercus coccinea, Q. rubra, and Q. velutina, respectively. Evidence suggests that moisture stress brought on by severe drought increases the susceptibility of Quercus species to the shoe-string fungus Armillaria mellea, which may result in significant shifts in canopy composition in these forests.

Clinton, B.D., J.A. Yeakley, and D.K. Apsley. 2003. Tree growth and mortality in a southern Appalachian deciduous forest following extended wet and dry periods. Castanea: 68(3): 189-200.

Abstract
We inventoried two 1-ha plots on opposing watersheds (WS2-WS-S, WS18-WS-N) three times (1983, 1989, 1998) over a 16-year period to contrast how differing precipitation (P) regimes affect tree mortality. From 1983 to 1989, annual precipitation averaged 16.5% less than the 64-year mean; from 1989 to 1998, it averaged 12.2% above the mean. In 1989 and 1998, standing crop biomass, above ground net primary productivity, mortality rates and species composition were determined. In 1989, following the dry period, the highest mortality for canopy tree species was in Carya spp. And Quercus velutina in both watersheds. Following the wet period in 1998, mortality was highest in Cornus florida in both watersheds, presumably due to the Anthracnose fungus; however, net change in stem density due to ingrowth was positive for this species in the WS-S watershed (+34%) and negative in the WS-N watershed (-18%). Estimated ANPP for WS-S was 10 and 1,076 kg ha-1yr-1for the periods 1983-89 and 1989-98, respectively. In contrast, ANPP on WS-N was 679 and 93 kg ha-1yr-1 for the same periods. Differences in ANPP are due to higher rates of mortality on WS-N compared with WS-S. In this study, species specific rates of mortality varied by watershed, and were likely due to microclimate-related increased susceptibility at the species level to certain proximal causes.

Clinton, B.D., J.M. Vose, and W.T. Swank. 1996. Shifts in aboveground and forest floor carbon and nitrogen pools after felling and burning in the Southern Appalachians. Forest Science. 42(4): 431-441.

Abstract
Changes in aboveground and forest floor mass, carbon (C), and nitrogen (N) pools were quantified on three sites in the southern Appalachians 2 yr after felling and burning. Before felling and burning, stands were characterized by sparse overstories and dense Kalmia latifolia L. understories. Two years after burning, foliar C and N pools had reached 25% and 29% of pretreatment levels, respectively. Foliar N concentrations were not different from pretreatment values. Standing wood C and N pools were 1% and 2%, respectively, of pretreatment values. Wood N concentrations were significantly higher on two sites, likely related to differences in fire intensity. Forest floor N content 2 yr after burning was 90% of pretreatment levels, most contained in unconsumed large woody material. Forest floor mass was significantly lower in the Oi layer and unchanged in the Oe + Oa layers. Forest floor N concentrations were generally lower after treatment. The site with the least intense fire and the lowest mass loss from the forest floor had the highest forest floor, foliage, and wood N concentrations 2 yr after burning. Site recovery after felling and burning was a function of fire severity and the capacity for site-nutrient retention through plant uptake.

Clinton, B.D., J.M. Vose, D.A. Vroblesky, and G.J. Harvey. 2004. Determination of the relative uptake of ground vs. surface water by Populus deltoids during phytoremediation. International Journal of Phytoremediation. 6(3): 239-252.

Abstract
Use of plants to remediate polluted groundwater is becoming an attractive alternative to more expensive traditional techniques. In order to adequately assess the effectiveness of the phytoremediation treatment; a clear understanding of water-use habits by the selected plant species is essential. We examined the relative uptake of surface water (i.e., precipitation) vs. groundwater by mature Populus deltoids by applying irrigation water at a rate equivalent to a 5-cm rain event. We used stable isotopes by hydrogen (D) and oxygen (18O) to identify groundwater and surface water (irrigation water) in the xylem sap water. Pretreatment isotopic ratios of both deuterium and 18O, ranked from heaviest to lightest, were irrigation water > groundwater > xylem sap. The discrepancy in preirrigation isotopic signatures between groundwater and xylem sap suggests that in the absence of a surface source of water (i.e., between rain events) there is an unknown amount of water being extracted from sources other than groundwater (i.e., soil surface water). We examined changes in volumetric soil water content (%), total hourly sapflux rates, and trichlororthene (TCE) concentrations. Following the irrigation treatment, volumetric soil water increased by 86% and sapflux increased by as much as 61%. Isotopic signatures of the xylem sap became substantially heavier following irrigation, suggesting that the applied irrigation water was quickly taken up by the plants. TCE concentrations in the xylem sap were diluted by an average of 21% following irrigation; however, dilution was low relative to the increase in sapflux. Our results show that water use by Populus deltoids is variable. Hence, studies addressing phytoremediation effectiveness must account for the relative proportion of surface vs. groundwater uptake.

Clinton, B.D., L.R. Boring, and W.T. Swank. 1994. Regeneration patterns in canopy gaps of mixed-oak forests of the southern Appalachians: influences of topographic position and evergreen understory. American Midland Naturalist 132: 308-319.

Abstract
Canopy gaps in southern Appalachian forests were assessed for the effects of topographic, gap, and stand variables on density of woody seedlings. Density was significantly correlated with percent slope and gap age (1-5 yr), varied substantially among topographic positions, and increased with gap size. Species richness decreased over time and increased with gap size. Regeneration was dominated by Acer rubrum L. Other species included Quercus coccinea Muench., Q. rubra L., Q. velutina Lamarck, Liriodendron tulipifera L., and Cornus florida L. Effects of the evergreen understory (Rhododendron maximum L. and Kalmia latifolia L.) were examined. Gaps containing over 50% cover of R. maximum had significantly lower densities than all other gaps, including gaps with >50% K. latifolia cover. Height distributions of regenerating species were skewed away from small (<15 cm) height classes. Species establishment was a function of gap area, gap age, topographic position, and cover of R. maximum. In addition, species of varying degrees of tolerance of understory conditions are capable of establishment in small to medium size canopy openings in the absence of evergreen shrub understory.

Clinton, Barton D.; Vose, James M.; Fowler, Dick L. 2010. Flat Branch monitoring project: stream water temperature and sediment responses to forest cutting in the riparian zone. Res. Pap. SRS–51. Asheville, NC: U.S. Department of Agriculture Forest Service, Southern Research Station. 8 p.

Abstract
Stream water protection during timber-harvesting activities is of primary interest to forest managers. In this study, we examine the potential impacts of riparian zone tree cutting on water temperature and total suspended solids. We monitored stream water temperature and total suspended solids before and after timber harvesting along a second-order tributary of the Coleman River in northeastern Georgia, where logging with rubber-tired skidders was conducted in the riparian area along alternating 60-m stream reaches on the east side of the stream. We monitored temperature above the management unit (reference), at a location within the cut area (within cut), and at a third site 150 m below the cut area (below cut). We measured total suspended solids during base flow and storm flow, taking weekly stream water grab samples above the site and above and below each riparian area, for a total of six sampling locations. We found that stream water temperature following harvest increased within the cut area relative to the reference but decreased at the below sample site back to reference conditions. Overall, total suspended solids responses were minimal or nonexistent during base and storm flows within the cut relative to the reference site, and temperature responses were minimal. Unusually warm and dry weather existed for most of the logging period, which may have minimized the potential for runoff, erosion, and sediment; however, low flows may have contributed to the small increases in water temperature. Hence, we observed only marginal effects of riparian zone cutting on water temperature and total suspended solids in this study.

Cofer, T. M., K. J. Elliott, J. K. Bush, and C. F. Miniat. 2018. Rhododendron maximum impacts seed bank composition and richness following Tsuga canadensis loss in riparian forests. Ecosphere 9(4):e02204. 10.1002/ecs2.2204

Abstract
Southern Appalachian riparian forests have undergone changes in composition and function from invasive pathogens and pests. Castanea dentata mortality in the 1930s from chestnut blight (Cryphonectria parasitica) and Tsuga canadensis mortality in the 2000s from the hemlock woolly adelgid (Adelges tsugae) have led to the expansion and increased growth of Rhododendron maximum, an evergreen subcanopy shrub. A better understanding of seed bank characteristics and the various abiotic and biotic factors that affect the seed bank may be useful in determining the restoration potential of forest communities following invasion-related disturbances. We compared the seed bank of two deciduous forest types: hardwood forests with a dense R. maximum subcanopy (hereafter, RR) and hardwood forests without R. maximum (hereafter, HWD). We evaluated numerous microenvironmental variables through principal component analysis (PCA) and correlated the derived PCA axes scores to seed bank density and richness across forest types. We found that seed bank density was comparable between the forests types; however, seed bank richness was much lower in RR than HWD and the species composition was dissimilar between forest types. Twenty-eight of 64 (44%) species in the seed bank of HWD were not found in the seed bank of RR. Species that were represented in both forest types were often found in contrasting densities. Most notably, seed bank densities of several woody species were considerably higher in RR (85%) than HWD (45%), while herbaceous seed bank density was lower in RR (11%) than HWD (50%). Mineral soil pH, soil nutrient availability, and soil moisture were lower, and organic soil (Oi + Oe + Oa) depth and mass were greater in the RR than HWD forest type. PCA correlations revealed that PCA4 (represented by understory density and Oe + Oa phosphorus and carbon/nitrogen ratio) was negatively correlated with total seed bank density. PCA1 (represented by Oe + Oa cations and phosphorus, understory richness, ground-layer cover, and mineral soil pH) and PCA4 were positively correlated with total seed bank richness. These results suggest that the soil seed bank will not be the primary mode of recruitment to establish a diverse and herbaceous-rich community if a RR is present.

Cohen, Emily B, Scott M. Pearson and Frank R. Moore. 2014. Effects of landscape composition and configuration on migrating songbirds: inference from an individual-based model. Ecological Applications 24(1):169-180.

Abstract
The behavior of long-distance migrants during stopover is constrained by the need to quickly and safely replenish energetic reserves. Replenishing fuel stores at stopover sites requires adjusting to unfamiliar landscapes with little to no information about the distribution of resources. Despite their critical importance to the success of songbird migration, the effects of landscape composition and configuration on fuel deposition rates (FDR [g/d]), the currency of migration, has not been tested empirically. Our objectives were to understand the effects of heterogeneous landscapes on FDR of forest-dwelling songbirds during spring migration. The results of field experiments were used to parameterize a spatially explicit, individual-based model of forest songbird movement and resulting FDR. Further field experiments were used to validate the results from the individual-based model. In simulation experiments, we altered a Gulf South landscape in a factorial design to predict the effects of future patterns under different scenarios of land use change in which the abundance of high-quality hardwood habitat and the spatial aggregation of habitat varied. Simulated FDR decreased as the amount of hardwood in the landscape decreased from 41% to 22% to 12%. Further, migrants that arrived in higher-quality habitat types gained more mass. Counter to our expectations, FDR was higher with lower spatial aggregation of habitat. Differences in refueling rates may be most influenced by whether or not an individual experiences an initial searching cost after landing in poor-quality habitat. Therefore, quickly locating habitat with sufficient food resources at each stopover may be the most important factor determining a successful migration. Our findings provide empirical evidence for the argument that hardwood forest cover is a primary determinant of the quality of a stopover site in this region. This study represents the first effort to empirically quantify FDRs based on the configuration of landscapes.

Colchero, F., R. A. Medellin, J. S. Clark, R. Lee, and G. G. Katul. 2009. Predicting population survival under future climate change: density dependence, drought and extraction in an insular bighorn sheep. Journal of Animal Ecology, 78:666-673.

Abstract
1. Our understanding of the interplay between density dependence, climatic perturbations, and conservation practices on the dynamics of small populations is still limited. This can result in uninformed strategies that put endangered populations at risk. Moreover, the data available for a large number of populations in such circumstances are sparse and mined with missing data. Under the current climate change scenarios, it is essential to develop appropriate inferential methods that can make use of such data sets. 2. We studied a population of desert bighorn sheep introduced to Tiburon Island, Mexico in 1975 and subjected to irregular extractions for the last 10 years. The unique attributes of this population are absence of predation and disease, thereby permitting us to explore the combined effect of density dependence, environmental variability and extraction in a ‘controlled setting.’ Using a combination of nonlinear discrete models with long-term field data, we constructed three basic Bayesian state space models with increasing density dependence (DD), and the same three models with the addition of summer drought effects. 3. We subsequently used Monte Carlo simulations to evaluate the combined effect of drought, DD, and increasing extractions on the probability of population survival under two climate change scenarios (based on the Intergovernmental Panel on Climate Change predictions): (i) increase in drought variability; and (ii) increase in mean drought severity. 4. The population grew from 16 individuals introduced in 1975 to close to 700 by 1993. Our results show that the population’s growth was dominated by DD, with drought having a secondary but still relevant effect on its dynamics. 5. Our predictions suggest that under climate change scenario (i), extraction dominates the fate of the population, while for scenario (ii), an increase in mean drought affects the population’s probability of survival in an equivalent magnitude as extractions. Thus, for the long-term survival of the population, our results stress that a more variable environment is less threatening than one in which the mean conditions become harsher. Current climate change scenarios and their underlying uncertainty make studies such as this one crucial for understanding the dynamics of ungulate populations and their conservation.

Coleman, D.C. 1999. Book review of Major Biological Issues Resulting from Anthropogenic Disturbance of the Nitrogen Cycle. Soil Biology and Biochemistry 31 (1999): 1599-1601.

Abstract
Coleman reviews the book, Major Biological Issues Resulting from Anthropogenic Disturbance of the Nitrogen Cycle (edited by Mansfield, Goulding, and Sheppard). He writes that dogmas are being broken, ranging from how plants respond to NHX, how ozone acts in cells, effects of visible symptoms related to growth effects and finally, a plea for more consideration of wild plants, expanding out from a few well-studied species of crop plants. In all cases, much remains to be learned, and the reader of this well-edited and summarised volume will be the richer for carefully reading and studying it.

Coleman, D.C. 2008. From peds to paradoxes: Linkages between soil biota and their influences on ecological processes. Soil Biology & Biochemistry. 40: 271-289.

Abstract
Soils and their biota have been studied by a variety of observational and experimental methods that have allowed biologists to infer their structural and functional interactions. Viewing progress made over the last 10 years, it is apparent that an increasing diversity of analytical and chemical methods are providing much more detailed information about feeding preferences and niche overlaps of speciose groups such as oribatid mites. Other topics in which considerable progress has been made include new advances in knowledge of root and mycorrhiza production and turnover and their impacts on soil ecosystems; soil biota, exudations and secretions and soil aggregation phenomena; the biology of invasive species in soils;soil biodiversity, legacies and linkages to soil processes; and soil biodiversity and ecosystem functional responses. Throughout the review, the author suggests ways for new progress to be made in future research.

Coleman, D.C., and W.B. Whitman. 2005. Linking species richness, biodiversity and ecosystem function in soil systems. Pedobiologia. 49: 479-497.

Abstract
Soils are the central organizing entities in terrestrial ecosystems and possess extremely diverse prokaryotic and eukaryotic biota. They are physically and chemically complex, with micro- and macro-aggregates embedded within a solid, liquid and gaseous matrix that is continually changing in response to natural and human-induced perturbations. Recent advances in molecular techniques in systematics have provided opportunities for the study of biodiversity and biocomplexity of soil biota. A symposium and workshop on soil biogeochemistry and biodiversity International Symposium on Impacts of Soil Biodiversity on Biogeochemical Processes in Ecosystems, Taiwan Forestry Research Institute, Taipei, Taiwan April 18-24, 2004. Convened an international array of participants working in biomes on virtually every continent on the planet (ranging from polar to tropical regions). This special issue reports on the theoretical bases and applications of molecular methods for the measurement of soil biodiversity. Themes addressed include a melding of classical taxonomic investigations with biochemical fingerprinting and molecular probing of organism identities. Several papers highlight new advances in identifications of prokaryotic and eukaryotic organisms. Examples include new developments in ¬¬fingerprinting¼¼ of microbes active in ¬¬mycorrhizospheres¼¼ using immunocapture and other innovative techniques. Developments in the study of impacts of invasive plant and animal species on ecosystem function and subsequent microbial community composition and function have been very great in the last 2-3 years. Soils are major repositories of legacies, including fine and coarse woody debris and other organic products, which have feedbacks on soil diversity. The ways in which species diversity and function of microbial and faunal communities interact and their importance to ecosystem function are examined in biological and biochemical detail.

Coleman, D.C., E.P. Odum, and D.A. Crossley Jr. 1992. Soil biology, soil ecology, and global change. Biology and Fertility of Soils 14: 104-111.

Abstract
This overview paper addesses aspects of scaling in space and time, and scaling in relation to micro- and macrohabitats.

Coleman, D.C., M.D. Hunter, J. Hutton, S. Pomeroy, and L. Swift Jr. 2002. Soil respiration from four aggrading forested watersheds measured over a quarter century. Forest Ecology and Management. 157: 247-253.

Abstract
Soil respiration was measured in four aggrading, forested second-growth watersheds in the southern Appalachians using an identical method (alkali absorption) at intervals 23 and 24 years apart. Seasonal trends were similar, with mid-summer maxima and winter minima. Amounts of carbon dioxide evolved were higher in the recent measurements (1995) compared to the earlier ones (1971-1972), despite similar soil water and temperature regimes. The overall trend across all four watersheds may reflect changes in organic matter levels and subsequent root growth.

Conor Keitzer, S. and Goforth, R. R. (2013), Salamander diversity alters stream macroinvertebrate community structure. Freshw Biol, 58: 2114–2125. doi:10.1111/fwb.12195

Abstract
1. Salamanders are abundant consumers in many fishless stream ecosystems, but few studies have explicitly examined their ecological role. Stream-dwelling salamander larvae are generalist predators of aquatic macroinvertebrates and may play an important role in structuring macroinvertebrate communities. The potential for emergent effects of multiple predator species suggests that changes in salamander diversity could alter their effects on macroinvertebrate communities, but this has not been tested. 2. We used in-stream enclosures to manipulate the presence and diversity of the two most abundant salamanders, Eurycea wilderae (EWIL) and Desmognathus quadramaculatus (DQUA), in a southern Appalachian Mountain headwater stream to examine the impacts of salamander predation on macroinvertebrate communities. We were particularly interested in testing for potential diversity effects by comparing the effects of each species in monoculture to polycultures of both species (BOTH). 3. Salamanders reduced macroinvertebrate abundance compared to the control treatment (CONTROL), but only when both species were present together. The general pattern of macroinvertebrate abundance among treatments was: CONTROL = EWIL = DQUA > BOTH, although no treatment significantly reduced the abundance of epibenthic taxa. The BOTH treatment also significantly altered macroinvertebrate community structure and reduced taxon richness by c. 57%. The effects of salamanders were particularly pronounced for chironomids (Diptera: Chironomidae), which comprised the majority of macroinvertebrate total abundance. 4. Increased salamander diversity substantially altered macroinvertebrate communities, suggesting that niche complementarity or facilitation occurred despite the apparent functional similarity of these two species. Therefore, changes in salamander diversity may alter the effects of salamander communities on macroinvertebrates, which may cascade through food webs to affect stream ecosystem function.

Cook, D., DeCrescenzo, E., Upchurch, R., Peterson, J. 2007. Isolation of Polymer-Degrading Bacteria and Characterization of the Hindgut Bacterial Community from the Detritus-Feeding Larvae of Tipula abdominalis (Diptera: Tipulidae). Applied and Environmen

Abstract
The Tipula abdominalis larval hindgut microbial community presumably facilitates digestion of the lignocellulosic diet. The microbial community was investigated through characterization of bacterial isolates and analysis of 16S rRNA gene clone libraries. This initial study revealed novel bacteria and provides a framework for future studies of this symbiosis.

Coombs, S., and G.D. Grossman. 2006. Mechanosensory based orienting behaviors in fluvial and lacustrine populations of mottled sculpin (Cottus bairdi). Marine and Freshwater Behaviour and Physiology. 39(2): 113-130.

Abstract
We compared prey-orienting and rheotactic behaviors in a fluvial (Coweeta Creek) and lacustrine (Lake Michigan) population of mottled sculpin. Blinded sculpin from both populations exhibited unconditioned, mechanosensory based rheotaxis to low velocity flows. Whereas Lake Michigan sculpin generally showed increasing levels of positive rheotaxis to increasing velocities, Coweeta Creek sculpin show varying levels of positive rheotaxis at low to intermediate velocities and often reduced positive rheotaxis or even negative rheotaxis at the highest velocities (12 cm s-1). Blinded Lake Michigan, but not Coweeta Creek mottled sculpin exhibited an orienting response to a small (3mm diameter) artificial prey (50 Hz vibrating sphere). In conclusion, the two populations differed in the strength and polarity of the rheotactic response at higher velocities and in their responsiveness to mechanosensory cues from epibenthic prey sources. These behavioral differences have most likely arisen from different learning experiences in different habitats and from the greater importance of visual cues to the Coweeta Creek mottled sculpin and mechanosensory cues to Lake Michigan mottled sculpin in the sensory guidance of orienting behaviors.

Cornaby, B.W., and J.B. Waide. 1973. Nitrogen fixation in decaying chestnut logs. Plant and Soil 39: 445-448.

Abstract
Nitrogen fixation is shown to occur in decaying logs of American chestnut, Castanea dentata (Marsh.) Borkh., by acetylene reduction techniques, and its significance is considered in relation to log decomposition in forest ecosystems.

Costa, J.T. III, and D.A. Crossley Jr. 1991. Diel patterns of canopy arthropods associated with three tree species. Environmental Entomology 20: 1542-1548.

Abstract
Canopy arthropods on dogwood, red maple, and yellow poplar were bag-sampled during the day and night on six dates from July through September on Coweeta ws7. Numbers of canopy arthropods taxa were similar both between and within tree species, as was relative taxon abundance. However, there were substantial differences in faunal composition and weighted arthropod numbers between daytime and nighttime canopies. These data suggest that canopy foliage may support greater densities and kinds of arthropods than those priviously reported based on daytime sampling only. Experimental designs that include diel sampling would provide a more complete assessment of the srtucture and composition on canopy communities.

Coughlan, Michael R. 2013. Errakina: Pastoral Fire Use and Landscape Memory in the Basque Region of the French Western Pyrenees. Journal of Ethnobiology 33(1): 86-104.

Abstract
People in the French Western Pyrenees have used fire for millennia in order to shape and manage landscapes. This history has left cultural and ecological legacies that both reflect and ensure the relative persistence of landscape patterns and processes. In this paper I draw on ethnographic research, ethnohistorical evidence, and Bayesian spatial analyses of historical fire use locations and land use maps to shed some light on human-firelandscape dynamics in the Pyrenees for the years 1830 to 2011. I show how cultural and ecological legacies reflect a self-organized fire management regime that emerges from fire use driven by the production goals of individual households. I frame the self-organizing dynamic inherent in Pyrenean pastoral fire use as ‘‘landscape memory.’’ This conclusion has implications for the future direction of fire-related conservation policy for the Pyrenees and for analogous systems characterized by self-organized land management regimes.

Coughlan, Michael R. 2013. Farmers, flames, and forests: Historical ecology of pastoral fire use and landscape change in the French Western Pyrenees, 1830-2011. Forest Ecology and Management.

Abstract
The human use of fire is a major disturbance factor shaping the long term composition and patterning of temperate forest landscapes. Yet, knowledge of the role of human agency in the historical dynamics of fire in temperate forests remains vague. This paper presents a cross-scale Bayesian Weights of Evidence analysis of change in the spatial patterns of fire use over the last 180 years for a village territory in the Basque portion of the French Pyrenees. Research investigated the historical relationships between social institutions that control land use, the spatial patterning of fire use, and landscape change. Analysis considered the spatial contexts within which humans use and manage land: the household institution and the parcel unit of land management. Bayesian methods established statistically significant associations between social and ecological factors driving fire use and landscape change. These associations suggest that social institutions differentially affected fire use patterns through inherited constraints. The resulting socioecological legacies helped to explain the spatial patterns of landscape change. Uncertainty highlighted in the modeling process suggests that we need a better understanding of the historical ecological dynamics of household institutions and land use change in order to better explain relationships between variability in land use intensity and the fire regime.

Coughlan, Michael R. 2013. Unauthorized Firesetting as Socioecological Disturbance: A Spatiotemporal Analysis of Incendiary Wildfires in Georgia, USA, 1987-2010. Fire Ecology 9(3): 45-63.

Abstract
I analyzed the spatiotemporal patterning of intentional, unauthorized landscape fires in the state of Georgia, USA, for the years 1987 through 2010 with the aim of delineating socioecological constraints on and firesetter preferences for the timing and placement of ignitions. Unauthorized fires represent complex phenomena through which actors compete over social and ecological outcomes that transcend the spatiotemporal confines of individual fires themselves. Current classificatory systems define unauthorized firesetting behavior as irrational, destructive, and malicious. Because landscape fires cause both positive and negative consequences for biological diversity and ecosystems services, perceived costs and benefits of fires are contestable and relative to point of view. The locational and temporal patterns of unauthorized landscape fires examined in this study do not show firesetter preferences for maximizing damage to landscapes. Instead, unauthorized fires in Georgia potentially contribute to the maintenance of landscapes adapted to frequent, dormant- and early growing-season fire regimes.

Coughlan, Michael R. and T.L. Gragson. 2016. An Event History Analysis of Parcel Extensification and Household Abandonment in Pays Basque, French Pyrenees, 1830–1958 AD. Human Ecology. DOI:10.1007/s10745-016-9808-y.

Abstract
This paper examines local processes of agricultural abandonment, socioeconomic changes, and associated landscape transition in a Pyrenean mountain village. We analyze the effects of socioeconomic and demographic factors contributing to changes in parcel level land use and ownership from 1830 to 1958. We use an event-history analysis to examine how individual etxe (Basque households) influenced the pace and character of landscape transition through their internal composition and their mediation of market pressures. Contrary to conventional narratives of agricultural transitions, our analysis suggests that more rapid "abandonment" of the landscape was prevented by etxe that were able to both engage in markets and maintain higher fertility rates. We conclude that the capacity of agropastoral landscapes to absorb broadscale change is directly tied to local institutions, such as the etxe, which ultimately mediate socioeconomic drivers of change.

Coughlan, Michael. R. 2016. Wildland Arson as Clandestine Resource Management: A Space-Time Permutation Analysis and Classification of Informal Fire Management Regimes in Georgia, USA. Environmental Management. DOI:10.1007/s00267-016-0669-3.

Abstract
Forest managers are increasingly recognizing the value of disturbance-based land management techniques such as prescribed burning. Unauthorized, ‘‘arson’’ fires are common in the southeastern United States where a legacy of agrarian cultural heritage persists amidst an increasingly forest-dominated landscape. This paper reexamines unauthorized fire-setting in the state of Georgia, USA from a historical ecology perspective that aims to contribute to historically informed, disturbance-based land management. A space–time permutation analysis is employed to discriminate systematic, management-oriented unauthorized fires from more arbitrary or socially deviant fire-setting behaviors. This paper argues that statistically significant space–time clusters of unauthorized fire occurrence represent informal management regimes linked to the legacy of traditional land management practices. Recent scholarship has pointed out that traditional management has actively promoted sustainable resource use and, in some cases, enhanced biodiversity often through the use of fire. Despite broad-scale displacement of traditional management during the 20th century, informal management practices may locally circumvent more formal and regionally dominant management regimes. Space–time permutation analysis identified 29 statistically significant fire regimes for the state of Georgia. The identified regimes are classified by region and land cover type and their implications for historically informed disturbance-based resource management are discussed.

Coulson, R.N., D.A. Crossley Jr., and C.S. Gist. 1971. Patterns of Coleoptera species diversity in contrasting white pine and coppice canopy communities. American Midland Naturalist 86: 145-151.

Abstract
The information-theory index H(s) and the index D were used to measure the pattern of diversity of Coleoptera species in coppice hardwoods and white pine canopy communities. The distribution of individuals within species was measured by using redundancy and evenness indices. Diversity in the coppice was greater than in the white pine. The coppice canopy community followed a seasonal trend in diversity, evenness, and redundancy. Diversity in the white pine community did not follow an apparent seasonal trend. Considerably fewer species and individuals occurred in the white pine, which tended to magnify the importance of the appearance and disappearance of dominant species and thereby to obliterate any seasonal trend in diversity, redundancy, and evenness.

Coulson, R.N., R.T. Franklin, and D.A. Crossley Jr. 1970. A self-maintaining window trap for collecting flying insects. Entomological News 81: 164.

Abstract
An automatic drain system and the use of a preservative that is lighter than water are discussed as modifications of window flight traps.

Coulston, P.J., and O.E. Maughan. 1983. Effects of removal of instream bebris on trout populations. The Journal of the Elisha Mitchell Scientific Society. 99(3): 78-85.

Abstract
In Poplar Creek and South Fork Mills River, North Carolina, the occurrence of debris as cover for brown trout (Salmo truttd) and rainbow trout (Salmo gairdneri) was directly correlated with fish numbers and biomass. Cover was the limiting factor for larger fish. The limiting factor for small fish was a variable associated with flow or substrate size. The decision on whether to remove debris should be based on the identification of limiting factors and a clear formulation of the intended outcome. If the management objective is to maintain the number of large fish, debris removal should be discouraged.

Courtney, G.W. 1994. Biosystematics of the Nymphomyiidae (Insecta:Diptera): life history, morphology, and phylogenetic relationships: Smithsonian contributions to zoology. no. 550. Smithsonian Institution Press, Washington, DC.

Abstract
The family Nymphomyiidae was redescribed using additional larval, pupal and adult characteristics. The revised family includes seven species, two of which are new. Nymphomyia dolichopeza is widespread and locally abundant in streams of the southern Blue Ridge Mountains, primarily in North Carolina and Georgia. World species of Nymphomyia are divided into two groups: (1) alba group (alba, levanidovae, and rohdendorfi; and (2) walkeri group (walkeri, dolichopeza, brundini, and holoptica). Keys to each life stage are provided.

Courtney, G.W. 1998. A method for rearing pupae of net-winged midges (Diptera: Blephariceridae) and other torrenticolous flies. In Proceedings of the Entomological Society of Washington. 100(4): 742-745.

Abstract
A method for obtaining reared adults of net-winged midges (Diptera: Blephariceridae) is presented. Rocks with attached pupae are removed from the stream and placed in a container maintained at high humidity. Survival and emergence rates exceeding 60% were recorded for several species of Nearctic Blepharicera. This method is ideal for associating pupae and adults of blepharicerids and other torrenticolous flies.

Craig, M.E. and Fraterrigo, J.M. 2017. Plant–microbial competition for nitrogen increases microbial activities and carbon loss in invaded soils. Oecologia. doi:10.1007/s00442-017-3861-0

Abstract
Many invasive plant species show high rates of nutrient acquisition relative to their competitors. Yet the mechanisms underlying this phenomenon, and its implications for ecosystem functioning, are poorly understood, particularly in nutrient-limited systems. Here, we test the hypothesis that an invasive plant species (Microstegium vimineum) enhances its rate of nitrogen (N) acquisition by outcompeting soil organic matter-degrading microbes for N, which in turn accelerates soil N and carbon (C) cycling. We estimated plant cover as an indicator of plant N acquisition rate and quantified plant tissue N, soil C and N content and transformations, and extracellular enzyme activities in invaded and uninvaded plots. Under low ambient N availability, invaded plots had 77% higher plant cover and lower tissue C:N ratios, suggesting that invasion increased rates of plant N acquisition. Concurrent with this pattern, we observed significantly higher mass-specific enzyme activities in invaded plots as well as 71% higher long-term N availability, 21% lower short-term N availability, and 16% lower particulate organic matter N. A structural equation model showed that these changes were interrelated and associated with 27% lower particulate organic matter C in invaded areas. Our findings suggest that acquisition of N by this plant species enhances microbial N demand, leading to an increased flux of N from organic to inorganic forms and a loss of soil C. We conclude that high N acquisition rates by invasive plants can drive changes in soil N cycling that are linked to effects on soil C.

Craig, Metthew E.,Scott M. Pearson, Jennifer M. Fraterrigo, 2015. Grass invasion effects on forest soil carbon depend on landscape-level land use patterns. Ecology 96:2265-2279. doi: 10.1890/14-1770.1

Abstract
Plant invasions can alter the quality and quantity of detrital and root-derived inputs entering a system, thereby influencing the activities of microbial decomposers and affecting the soil carbon cycle. The effect of these inputs on soil carbon storage is often conflicting, suggesting strong context dependency in the plant–decomposer relationship. Whether there is a generalizable pattern that explains this dependency remains relatively unexplored. Here, we (1) examine how invasion by the exotic grass Microstegium vimineum affects carbon cycling across a land use gradient, and (2) evaluate the importance of inorganic nitrogen availability and other environmental variables for explaining patterns in soil carbon. Using paired invaded and uninvaded plots, we quantified invasion effects on belowground carbon pools, extracellular enzyme activities, and native leaf litter decomposition in forests embedded in an urban, agricultural, or forested landscape matrix. Compared to the urban matrix, invasion-associated declines in total soil organic carbon in the forested and agricultural landscapes were 3.5 and 2.5 times greater, respectively. Inorganic nitrogen availability and M. vimineum biomass interacted to explain these patterns: when both nitrogen availability and M. vimineum biomass were high, invaded soils exhibited higher total organic carbon, unchanged particulate organic matter carbon, and higher mineral-associated organic matter carbon compared to adjacent uninvaded soils. Consistent with these patterns, activities of carbon-mineralizing enzymes were lower in invaded than in uninvaded soils when both nitrogen availability and M. vimineum biomass were high. By contrast, decomposition of native leaf litter was faster when inorganic nitrogen availability and M. vimineum biomass were high. Our findings suggest that, although this invader may accelerate carbon cycling in forest soils, its effects on soil carbon storage largely depend on nitrogen availability and invader biomass, which can be altered by landscape-level patterns of land use. Additional research is needed to determine whether land use or other broad-scale processes such as atmospheric nitrogen deposition can explain context dependence in plant invasion effects on other ecosystem processes.

Creed, I.F., Spargo, A.T., Jones, J.A., Buttle, J.M., Adams, M.B., Beall, F.D., Booth, E., Campbell, J., Clow, D., Elder, K., Green, M.B., Grimm, N.B., Miniat, C., Ramlal, P., Saha, A., Sebestyen, S., Spittlehouse, D., Sterling, S., Williams, M.W., Winkler, R., and Yao, H. 2014. Changing forest water yields in response to climate warming: Results from long-term experimental watershed sites across North America. Global Change Biology. 20(10): 3191-3208. DOI: 10.1111/gcb.12615

Abstract
Climate warming is projected to affect forest water yields bu t the effects are expected to vary. We investigated how forest type and age affect water yield resilience to climate warming. To answer this quest ion, we examined the variability in his- torical water yields at long-term exper imental catchments across Canada and the United States over 5-year cool and warm periods. Using the theoretical framework of the Budyko curve, we calculated the effects of climate warming on the annual partitioning of precipitation ( P ) into evapotranspiration (ET) and water yield. Deviation ( d ) was defined as a catch- ment’s change in actual ET divided by P [AET/ P ; evaporative index (EI)] coincident with a shift from a cool to a warm period – a positive d indicates an upward shift in EI and smaller than expected water yields, and a negative d indicates a downward shift in EI and larger than expected water yields. Elasticity was defined as the ratio of interannual variation in potential ET divided by P (PET/ P ; dryness index) to interannual variation in the EI – high elasticity indicates low d despite large range in drying index (i.e., resili ent water yields), low elasticity indicates high d despite small range in dry- ing index (i.e., nonresilient water yields). Although the data needed to fully evaluate ecosystems based on these metrics arelimited,wewereabletoidentifysomecharacteristicsofre sponse among forest types. Alpine sites showed the greatest sensitivity to climate warming with any warming leading to in creased water yields. Conifer forests included catchments with lowest elasticity and stabl e to larger water yields. Deciduous forests inclu ded catchments with intermediate elasticity and stable to smaller water yields. Mixed coniferous/decidu ous forests included catchmen ts with highest elasticity and stable water yields. Forest type appeared to influence the re silience of catchment water yi elds to climate warming, with conifer and deciduous catchments more susceptible to clim ate warming than the more diverse mixed forest catchments

Crenshaw, C.L., H.M. Valett, and J.R. Webster. 2002. Effects of augmentation of coarse particulate organic matter on metabolism and nutrient retention in hyporheic sediments. Freshwater Biology. 47: 1820-1831.

Abstract
1. Metabolic and biogeochemical processes in hyporheic zones may depend on inputs of coarse particulate organic matter. Our research focused on how differing quantity and quality of organic matter affects metabolism and nutrient retention in the hyporheic zone of a first-order Appalachian stream. 2. Sixteen plots were established on a tributary of Hugh White Creek, NC, U.S.A. Sediment was extracted and treated with leaves, wood, plastic strips or remained unamended. Following treatment, sediment was returned to the stream and, approximately 3 months later, samples were removed from each plot. 3. Aerobic and anaerobic metabolism were measured as the change in O2 and CO2 in recirculating microcosms. At the same time, we monitored other possible terminal electron accepting processes and changes in nutrient concentrations. Aerobic metabolism was low in all treatments and respiratory quotients calculated for all treatments indicated that metabolism was dominated by anaerobic processes. 4. Rates of anaerobic respiration and total (combined aerobic and anaerobic) respiration were significantly greater (P < 0.05) in plots treated with leaf organic matter compared to controls. 5. Addition of leaves, which had a low C: N ratio, stimulated respiration in hyporheic sediments. Anaerobic processes dominated metabolism in both control and amended sediments. Enhanced metabolic rates increased retention of many solutes, indicating that energy flow and nutrient dynamics in the subsurface of streams may depend upon the quantity and quality of imported carbon.

Cressie, N., C. A. Calder, J. S. Clark, J. M. Ver Hoef, and C. K. Wikle. 2009. Accounting for uncertainty in ecological analysis: the strengths and limitations of hierarchical statistical modeling. Ecological Applications, 19:553-570.

Abstract
Analyses of ecological data should account for the uncertainty in the process(es) that generated the data. However, accounting for these uncertainties is a difficult task, since ecology is known for its complexity. Measurement and/or process errors are often the only sources of uncertainty modeled when addressing complex ecological problems, yet analyses should also account for uncertainty in sampling design, in model specification, in parameters governing the specified model, and in initial and boundary conditions. Only then can we be confident in the scientific inferences and forecasts made from an analysis. Probability and statistics provide a framework that accounts for multiple sources of uncertainty. Given the complexities of ecological studies, the hierarchical statistical model is an invaluable tool. This approach is not new in ecology, and there are many examples (both Bayesian and non-Bayesian) in the literature illustrating the benefits of this approach. In this article, we provide a baseline for concepts, notation, and methods, from which discussion on hierarchical statistical modeling in ecology can proceed. We have also planted some seeds for discussion and tried to show where the practical difficulties lie. Our thesis is that hierarchical statistical modeling is a powerful way of approaching ecological analysis in the presence of inevitable but quantifiable uncertainties, even if practical issues sometimes require pragmatic compromises.

Crocker, M.T., and J.L. Meyer. 1987. Interstitial dissolved organic carbon in sediments of a Southern Appalachian headwater stream. Journal of the North American Benthological Society 6(3): 159-167.

Abstract
Objectives were to compare seasonal and spatial patterns of dissolved organic carbon (DOC) and interstitial DOC (IDOC) concentrations at a headwater spring seep, and to explore interactions between sediment organic matter content, benthic bacterial biomass, water column DOC concentration, and sediment IDOC concentration and composition. Sediment organic matter content, IDOC concentration, water column DOC concentration, and benthic bacterial biomass were measured in a spring seep at Coweeta for two years. Organic matter content was increased or decreased in experimental sediments, and variables measured within three weeks of sediment manipulation and again after five and a half months. Benthic bacterial production was measured one week after sediment manipulation. Benthic organic matter is a source of IDOC, the concentration of which depends on sediment organic matter content, the relative proportion of high and low molecular weight IDOC compounds, and the exchange of interstitial and water column DOC.

Crocker, T.L., R.L. Hendrick, R.W. Ruess, K.S. Pregitzer, A.J. Burton, M.F. Allen, J. Shan, and L.A. Morris. 2003. . Applied Soil Ecology. 23: 127-135.

Abstract
Minirhizotrons provide a unique way to repeatedly measure the production and fate of individual root segments, while minimizing soil disturbance and the confounding of spatialvtemporal variation. However, the time associated with processing videotaped minirhizotron images limits the amount of data that can be extracted in a reasonable amount of time. We found that this limitation can be minimized using a more easily measured variable r (i.e. root numbers) as a substitute of root length. Linear regression models were fitted between root length versus root number for production and mortality of seven sample datasets of varying tree species and treatments. The resulting r2 values ranged from 0.79 to 0.99, suggesting that changes in root numbers can be used to predict root length dynamics reliably. Slope values, representing the mean root segment length (MRSL), ranged from 2.34 to 8.38mm per root segment for both production and mortality. Most treatments did not alter MRSL substantially, the exceptions being CO2 treatments and a girdling treatment that altered plant community composition and, consequently, root morphology. The high r2 values demonstrated a robust relationship between variables irrespective of species or treatments. Once the quantitative relationship between root lengths and numbers has been established for a particular speciesvtreatment combination, quantifying changes in root number through time should substantially decrease the time required to quantify root dynamics.

Croft, A.R., and M.D. Hoover. 1951. The relation of forests to our water supply. Journal of Forestry 49: 245-249.

Abstract
The authors use research findings to show how forest management practices affect the quality, quantity, and timing of water yield and discuss practical implications of forest management on the solution of water problems.

Cromack, K. Jr., P. Sollins, W. Graustein, K. Speidel, A. Todd, G. Spycher, C. Li, and R. Todd. 1979. Calcium oxalate accumulation and soil weathering in mats of hypogeous fungus Hysterangium crassum. Soil Biology and Biochemistry 11: 463- 468.

Abstract
Fungal mats of Hysterangium crassum Fischer occupied a mean of 9.6 percent of the upper 10 cm of soil developed under a 40- to 65-year-old stand of Douglas-fir in Oregon. This hypogeous basidiomycete exudes large amounts of oxalic acid, some of which precipitates with Ca in microscopic crystals of calcium oxalate. Soil oxalate concentration was significantly greater within fungal mats, and soil pH was significantly lower than in soil adjacent to mats. The quantity of Ca present as CaC2O4 is 0.5 the amount of exchangeable Ca in the soil and exceeds the mass of Ca lost annually in runoff.

Cromack, K., R.L. Todd, and C.D. Monk. 1975. Patterns of basidiomycete nutrient accumulation in conifer and deciduous forest litter. Soil Biology and Biochemistry 7: 265-268.

Abstract
Nutrient data were obtained for basidiomycete sporocarps, rhizomorphs and forest floor leaf litter samples collected from a white pine (Pinus strobus L.) watershed and from a mixed hardwood watershed. Basidiocarps taken from the surface litter of both watersheds were fleshy representatives of Agaricacae, Cantharellaceae or Clavariaceae. Forest floor basidiocarp samples (cap + stalk) from both watersheds had significantly greater concentrations of Cu, K, Na, P and Zn than the leaf litter from which they were removed. Bulked rhizomorph samples from both watersheds contained significantly more Ca, K, Na and Sr than forest floor leaf litter. Polyporaceae growing on hardwood branches concentrated Al, Mo, P and Zn.

Cross, W., Benstead, J., Rosemond, A., Wallace, J. 2003. Consumer-resource stoichiometry in detritus-based streams. Ecology Letters, 6:721-732

Abstract
Stoichiometric relationships between consumers and resources in detritus-based ecosystems have received little attention, despite the importance of detritus in most food webs. We analysed carbon ©, nitrogen (N), and phosphorus (P) content of invertebrate consumers, and basal food resources in two forested headwater streams (one reference and the other nutrient-enriched). We found large elemental imbalances between consumers and food resources compared with living plant-based systems, particularly in regard to P content, which were reduced with enrichment. Enrichment significantly increased nutrient content of food resources (consistent with uptake of N and P by detritus-associated microbes). P content of some invertebrates also increased in the enriched vs. reference stream, suggesting deviation from strict homeostasis. Nutrient content varied significantly among invertebrate functional feeding groups, orders and, to some extent, size classes. Future application of stoichiometric theory to detritus-based systems should consider the potential for relatively large consumer-resource elemental imbalances and P storage by insect consumers.

Cross, W., Wallace, J., Rosemond, A. 2007. Nutrient enrichment reduces constraints on material flows in a detritus-based food web. Ecology, 88(10): 2563-2575

Abstract
Most aquatic and terrestrial ecosystems are experiencing increased nutrient availability, which is affecting their structure and function. By altering community composition and productivity of consumers, enrichment can indirectly cause changes in the pathways and magnitude of material flows in food webs. These changes, in turn, have major consequences for material storage and cycling in the ecosystem. Understanding mechanisms and predicting consequences of nutrient-induced changes in material flows requires a quantitative food web approach that combines information on consumer energetics and consumer–resource stoichiometry. We examined effects of a whole-system experimental nutrient enrichment on the trophic basis of production and the magnitude and pathways of carbon ©, nitrogen (N), and phosphorus (P) flows in a detritus-based stream food web. We compared the response of the treated stream to an adjacent reference stream throughout the study. Dietary composition and elemental flows varied considerably among invertebrate functional feeding groups. During nutrient enrichment, increased flows of leaf litter and amorphous detritus to shredders and gatherers accounted for most of the altered flows of C from basal resources to consumers. Nutrient enrichment had little effect on patterns of material flows but had large positive effects on the magnitude of C, N, and P flows to consumers (mean increase of 97% for all elements). Nutrient-specific food webs revealed similar flows of N and P to multiple functional groups despite an order of magnitude difference among groups in consumption of C. Secondary production was more strongly related to consumption of nutrients than C, and increased material flows were positively related to the degree of consumer–resource C:P and C:N imbalances. Nutrient enrichment resulted in an increased proportion of detrital C inputs consumed by primary consumers (from ;15% to 35%) and a decreased proportion of invertebrate prey consumed by predators (from ;80% to 55%). Our results demonstrate that nutrient enrichment of detritus-based systems may reduce stoichiometric constraints on material flows, increase the contribution of consumers to C, N, and P cycling, alter the proportion of C inputs metabolized by consumers, and potentially lead to reduced ecosystem-level storage of C.

Cross, W.F., B.R. Johnson, J.B. Wallace, and A.D. Rosemond. 2005. Contrasting response of stream detritivores to long-term nutrient enrichment. Limnology and Oceanography. 50(6): 1730-1739.

Abstract
We examined growth and production responses of two dominant stream detritivores (chironomids and Tallaperla spp. stoneflies) at opposite ends of the ¬¬slow-fast¼¼ life-history continuum and with distinct feeding characteristics (i.e., consumption of fine particulate organic matter vs. leaf litter) to a 2-yr experimental nutrient enrichment of a headwater stream. Enrichment had large positive effects (~50% increase) on chironomid growth rates but no effects on those of Tallaperla spp. On an areal basis, enrichment had a large positive effect on chironomid production (~183% increase) but no detectable effect on the production of Tallaperla spp. When production data were examined on a per gram food basis, enrichment had an apparent positive effect on the production of both chironomids and Tallaperla spp. Together, these results suggest that nutrient-induced changes to organic matter quality had consistent and substantial positive effects on short lived chironomids, but effects were limited for longer-lived stoneflies. The lack of a system-wide effect on Tallaperla spp. may have been due to nutrient-induced reductions in leaf litter quantity, despite increases in litter quality. Our results indicate that species specific characteristics such as life span and dominant food type may be important in determining population- and community-level responses of consumers to nutrient enrichment of detritus-based aquatic ecosystems.

Cross, W.F., J.B. Wallace, A.D. Rosemond, and S.L. Eggert. 2006. Whole-system nutrient enrichment increases secondary production in a detritus-based ecosystem. Ecology. 87(6): 1556-1565.

Abstract
Although the effects of nutrient enrichment on consumervresource dynamics are relatively well studied in ecosystems based on living plants, little is known about the manner in which enrichment influences the dynamics and productivity of consumers and resources in detritus-based ecosystems. Because nutrients can stimulate loss of carbon at the base of detrital food webs, effects on higher consumers may be fundamentally different than what is expected for living-plant-based food webs in which nutrients typically increase basal carbon. We experimentally enriched a detritus-based headwater stream for two years to examine the effects of nutrient-induced changes at the base of the food web on higher metazoan (predominantly invertebrate) consumers. Our paired catchment design was aimed at quantifying organic matter and invertebrate dynamics in the enriched stream and an adjacent reference stream for two years prior to enrichment and two years during enrichment. Enrichment had a strong negative effect on standing crop of leaf litter, but no apparent effect on that of fine benthic organic matter. Despite large nutrient-induced reductions in the quantity of leaf litter, invertebrate secondary production during the enrichment was the highest ever reported for headwater streams at this Long Term Ecological Research site and was 1.2v3.3 times higher than predicted based on 15 years of data from these streams. Abundance, biomass, and secondary production of invertebrate consumers increased significantly in response to enrichment, and the response was greater among taxa with larval life spans _1 yr than among those with larval life spans .1 yr. Production of invertebrate predators closely tracked the increased production of their prey. The response of invertebrates was largely habitat-specific with little effect of enrichment on food webs inhabiting bedrock outcrops. Our results demonstrate that positive nutrient-induced changes to food quality likely override negative changes to food quantity for consumers during the initial years of enrichment of detritus-based stream ecosystems. Longer-term enrichment may impact consumers through eventual reductions in the quantity of detritus.

Cross, W.F., J.B. Wallace, and A.D. Rosemond. 2007. Nutrient enrichment reduces constraints on material flows in a detrius-based food web. Ecology. 88(10): 2563-2575.

Abstract
Most aquatic and terrestrial ecosystems are experiencing increased nutrient availability, which is affecting their structure and function. By altering community composition and productivity of consumers, enrichment can indirectly cause changes in the pathways and magnitude of material flows in food webs. These changes, in turn, have major consequences for material storage and cycling in the ecosystem. Understanding mechanisms and predicting consequences of nutrient-induced changes in material flows requires a quantitative food web approach that combines information on consumer energetics and consumer–resource stoichiometry. We examined effects of a whole-system experimental nutrient enrichment on the trophic basis of production and the magnitude and pathways of carbon (C), nitrogen (N), and phosphorus (P) flows in a detritus-based stream food web.

Cross, W.F., J.P. Benstead, A.D. Rosemond, and J.B. Wallace. 2003. Consumer-resource stoichiomentry in detritus-based streams. Ecology Letters. 6: 721-732.

Abstract
Stoichiometric relationships between consumers and resources in detritus-based ecosystems have received little attention, despite the importance of detritus in most food webs. We analysed carbon (C), nitrogen (N), and phosphorus (P) content of invertebrate consumers, and basal food resources in two forested headwater streams (one reference and the other nutrient-enriched). We found large elemental imbalances between consumers and food resources compared with living plant-based systems, particularly in regard to P content, which were reduced with enrichment. Enrichment significantly increased nutrient content of food resources (consistent with uptake of N and P by detritus-associated microbes). P content of some invertebrates also increased in the enriched vs. reference stream, suggesting deviation from strict homeostasis. Nutrient content varied significantly among invertebrate functional feeding groups, orders and, to some extent, size classes. Future application of stoichiometric theory to detritus-based systems should consider the potential for relatively large consumer-resource elemental imbalances and P storage by insect consumers.

Crossley, D. A. Jr., J.T. Callahan, C.S. Gist, J.R. Maudsley, and J.B. Waide. 1976. Compartmentalization of arthropod communities in forest canopies at Coweeta. Journal of the Georgia Entomological Society 11: 44-49.

Abstract
A compartment model is described for arraying arthropod biomasses of forest canopies into functional groups. Model inputs and outputs represent linkages to other processes within the watershed ecosystem. The compartment model is evaluated for its ability to contain standing crop and biomass information, using data obtained from sampling hardwood forest canopies in watersheds at Coweeta Hydrologic Laboratory.

Crossley, D.A. Jr., and J. Blair. 1991. A high-efficiency, low- technology Tullgren-type extractor for soil microarthropods. Agric., Ecos. and Environ. 34: 187-192.

Abstract
None

Crossley, D.A. Jr., and W.W. Hargrove. 1988. Ecology of Forest Insects. Quart. Rev. Biol. 63: 228.

Abstract
None

Crossley, D.A. Jr., R.N. Coulson, and C.S. Gist. 1973. Trophic level effects on species diversity in arthropod communities of forest canopies. Environmental Entomology 2: 1097-1100.

Abstract
Species diversity for arthropod communities inhabiting white pine and coppice canopies was measured using the Shannon Wiener information theory index, H(s), the Margalef index, D, and the Pielou evenness index, J . The two insect orders Coleoptera and Hymenoptera were investigated. The general index H(s) was significantly higher for the more diverse coppice stand than for the white pine monoculture, and was significantly higher for Hymenoptera than for Coleoptera. The other two indices demonstrated that differences in diversity between watersheds were due to greater species richness in the coppice, while differences between insect orders were due to greater evenness of individuals in the Hymenoptera. Since the Coleoptera were principally herbivores and the Hymenoptera predator-parasites, results can be interpreted in a trophic level context. It is suggested that, in a plant monoculture, low diversity is not propagated along food chains but rather - is recovered at higher trophic levels.

Cuffney, T.F., and J.B. Wallace. 1988. Particulate organic matter export from three headwater streams: discrete versus continuous measurements. Canadian Journal of Fisheries and Aquatic Science 45: 2010-2016.

Abstract
Particulate organic matter (POM) export from three small headwater streams was estimated using continuous and grab measurement methods for 2 yrs. Total annual POM export estimated from continuous mesurements was always greater than estimates made from grab samples. Continuous export samples were collected using a weir and gaging flume connected to a Coshocton proportional sampler designed to deliver 0.6% of discharge into a series of three settling barrels. The settling barrels removed a consistent proportion of POM (85-87%). The inability of the discrete method to adequately sample storm and bedload transport underestimates total annual export.

Cuffney, T.F., and J.B. Wallace. 1989. Discharge-export relationshipsin headwater streams: the influence of invertebrate manipulations and drought. Journal of the North American Benthological Society 8(4): 331-341.

Abstract
The roles of streamflow discharge and macroinvertebrate communities export of coarse and fine particulate organic matter (FPOM) were studied in three headwater streams. Two years of continuous discharge measurements were compared with export by two week intervals. The role of macroinvertebrates was examined by treating one of the three streams with an insecticide during Year 2 to reduce populations and alter community structure. Maximum discharge was the only discharge parameter which adequately predicted FPOM export. Regressions were unique for each stream and were constant between years despite a record drought.CPOM export was very sensitive to timing of CPOM inputs and storms. Treating with methoxychlor resulted in massive invertebrate drift and drastically reduced populations of macroinvertebrates, practically eliminating shredders and collector-filterers. Maximum discharge continued to be a good predictor of FPOM export. Relationships between export and discharge observed in this study are stronger than those reported elsewhere.

Cuffney, T.F., J.B. Wallace, and G.J. Lugthart. 1990. Experimental evidence quantifying the role of benthic invertebrates in organic matter dynamics of headwater streams. Freshwater Biology 23: 281-299.

Abstract
Insecticide methoxychlor was applied to a small stream. Initial application caused massive invertebrate drift and resulted in a community with few shredders and reduced abundances of most insect taxa. Bacterial densities and microbial respiration rates were not affected by treatment. Disruption of the invertebrate community caused significant reductions in leaf litter processing rates and fine particulate organic matter (FPOM) export. Declines were detectable within 1 week of treatment. Annual FPOM export was reduced to 33% of pretreatment levels. Course particulate organic matter export was not significantly influenced by treatment but was influenced by hydrologic differences among years.

Cuffney, T.F., J.B. Wallace, and J.R. Webster. 1984. Pesticide manipulation of a headwater stream: invertebrate responses and their significance for ecosystem processes. Freshwater Invertebrate Biology 3(4): 153-171.

Abstract
The influence of macroinvertebrates on detrital processing was evaluated by excluding them from one of two small Southern Appalachian streams by periodic applications of the insecticide methoxychlor. This caused massive invertebrate drift during the initial treatment and reduced aquatic insect densities and biomass to <10% of the levels within the adjacent untreated reference stream. Community structure in the treated stream shifted from a system dominated by small numbers of large shredding insects with comparatively low reproductive rates, to one dominated by large numbers of small collector-gatherers and predators with high reproductive rates. Non-insect invertebrate biomass and density became significantly higher in the treated stream than in the reference stream.

Cuffney, T.F., J.B. Wallace, and J.R. Webster. 1985. Influence of invertabrates on detrital processing in southern Appalachian streams: A manipulative approach. Freshwater Invertabrate Biology 3: 153-171.

Abstract
None

Cumming, G., Norwood, C., 2012. The Community Voice Method: Using participatory research and filmmaking to foster dialog about changing landscapes. Landscape and Urban Planning, Vol. 105:4, April 2012, p. 434-444

Abstract
The Community Voice Method is a stakeholder engagement approach designed to foster more inclusive, informed, and ongoing civic dialog in communities without a history of successful planning initiatives. The method begins with an iterative participatory research process, resulting in the creation of an original documentary film compiled from ethnographic interviews with a wide range of stakeholders. The film, which presents a research-based distillation of local civic discourse around the topic of interest, is used in combination with quantitative data presentations to stimulate deliberation during subsequent deliberative public meetings. Using findings from a Community Voice project in Macon County, North Carolina (USA), we argue that, by preceding public meetings with participatory research, the Community Voice Method was able to promote inclusive civic dialog; provide meeting participants with accessible, trustworthy information; and help build ongoing community capacity to address local land use issues.

Cushing, C.E., C.D. McIntire, J.R. Sedell, K.W. Cummins, G.W. Marshall, R.C. Peterson, and R.L. Vannote. 1980. Comparative study of physical-chemical variables of streams using multivariate analysis. Archiv fuer Hydrobiologie 89: 343-352.

Abstract
As a step toward the development of a system to categorize streams, 15 physical-chemical variables from 34 stream stations in North America and Europe were subjected to cluster and discriminant analyses to determine if discrete groupings were present, and, if so, which variables were most closely related to the among group variability. The log-transformed data provided five meaningful clusters of stream sites, but it was not possible to construct a simple and universally useful classification of running waters which includes physical, chemical, and biological aspects. Inclusion of biological variables is necessary to further assess the usefulness of the approach described here; work on this is in progress.

D'Angelo, D.J., and J.R. Webster. 1991. Phosphorus retention in streams draining pine and hardwoodcatchments in the southern Appalachian Mountains. Freshwater Biology. 26: 335-345.

Abstract
1. This study was designed to determine how catchment use affects stream phosphorus retention by comparing retention in streams draining three mixed hardwood catchments and three catchments that were planted in white pine in the 1950s. 2. Catchments of similar area and stream discharge were chosen and phosphorus uptake was measured monthly in each catchment along with temperature, discharge, velocity, coarse paniculate organic matter (CPOM), fine paniculate organic matter (FPOM), and microbial respiration associated with FPOM. 3. On an annual basis, average phosphorus retention was not different between streams draining pine and hardwood catchments nor were there significant differences between physical (temperature, velocity and discharge) or biological (CPOM, FPOM and respiration) parameters based on catchment type. However, discharge was more variable in streams draining pine catchments. 4. Because phosphorus uptake was correlated with discharge, phosphorus retention was also more variable in streams draining pine catchments. Storms caused a greater increase in discharge and loss of phosphorus in pine streams than in mixed hardwood streams, but discharge returned to baseline more quickly in pine streams. 5. We^ suggest that discharge regimes and phosphorus dynamics of streams draining pine catchments are less resistant to change but more resilient than streams draining mixed hardwood forests.

D'Angelo, D.J., and J.R. Webster. 1992. Natural and constrainment-induced factors influencing the breakdown of dogwood and oak leaves. Hydrobiologia. 237: 39-46.

Abstract
Breakdown rates and microbial colonization patterns of dogwood and oak leaves were measured between November and June of 1987-88 and 1988-89. Leaves were placed in artificial streams loose (unconstrained), in bags, or in packs. Discharge was maintained at approximately 0.25 I s " 1 , and no shredders were present in the streams. Average microbial biomass as ATP, for all species and treatments, increased from near 0 mg g~ ' AFDW in November to over 8 mg g~ l AFDW in June. Microbial respiration increased from about 0.01 ^g glucose respired hr-g~ ' AFDW in November to about 0.03 ^g hrg~ ' AFDW in June. Microbial biomass and activity were significantly greater on dogwood leaves than on oak leaves. Dogwood and oak leaf breakdown rates were fastest when unconstrained. -034 and -027 degree-day"' respectively. Breakdown rates of dogwood leaves were faster in bags (-025 degree-day"') than in packs (-015 degree-day"') while rates of oak leaves were not significantly different between bags and packs (-014 and -018 degree-day"' respectively). Breakdown rates of dogwood and oak leaves obtained in this study were much slower than those obtained by other investigators either in the presence or absence of shredders. A comparison of results from this study with results from other studies revealed that dogwood leaves may be affected more by turbulence, while oak leaves may be influenced more by shredder activity.

D'Angelo, D.J., J.R. Webster, and E.F. Benfield. 1991. Mechanisms of stream phosphorus retention: an experimental study. Journal of the North American Benthological Society. 10(3): 225-237.

Abstract
Using the spiralling concept, this study assessed the relative importance of temperature, current velocity, leaf biomass, fine particulate organic matter, and leaf type in determining phosphorus retention in woodland streams. To accomplish this objective, streamside artificial streams and two contrasting leaf types were used. A labile leaf type (dogwood), typical of successional forest vegetation, and a more refractory leaf type (oak) characteristic of mature forest species were chosen. Leaves were picked just before abscission and air dried. Dogwood leaves were added to three streams and oak leaves to three other streams. Phosphorus uptake experiments were conducted in the streams during November 1987-June 1988 and November 1988-June 1989. All streams were least retentive of phosphorus in December, the coldest month of the year, and more retentive in the warmer spring and summer months. Phosphorus uptake was not correlated with microbial biomass or activity on leaves or with leaf biomass. However, streams with oak leaves were more retentive than streams with dogwood leaves. Measurements of penetrance (i.e., weight required to push a metal rod through the leaf) revealed that dogwood leaves were softer than oak leaves. The soft dogwood leaves were less effective at retarding water flow and therefore velocity was typically faster in dogwood streams (p < 0.05; Pearson's correlation). This higher velocity apparently contributed to lower retention. These results suggest that phosphorus retention under conditions of this experiment was governed primarily by temperature and water velocity. Coarse and fine particulate organic matter biomass and composition did influence retention, but their impact was secondary to the effects of temperature and velocity.

D'Angelo, D.J., J.R. Webster, S.V. Gregory, and J.L. Meyer. 1993. Transient storage in Appalachian and Cascade mountain streams as related to hydraulic characteristics. Journal of the North American Benthological Society. 12(3): 223-235.

Abstract
Hydraulic characteristics were measured in artificial streams and in 1st- to 5th-order streams in the Appalachian and Cascade mountains. Appalachian Mountain stream sites at Coweeta Hydrologic Laboratory, North Carolina, were on six Ist-order streams and a 1st- through 4th-order gradient of Ball Creek-Coweeta Creek. Cascade Mountain sites were located on constrained and unconstrained reaches of Lookout Creek, a 5th-order stream in H. J. Andrews Experimental Forest, Oregon. At each site, a tracer solution (chloride or rhodamine WT) was released for 30-180 min and then discontinued. At the downstream end of the release site, the resulting rise and fall of the tracer concentration was measured. These data, along with upstream concentration and measured widths and depths, were used in a computer model to estimate several hydraulic parameters including transient storage and lateral inflow. Estimated transient storage zone size (A,) ranged from near zero in artificial streams to 2.0 m2 in 5th-order streams. A, was largest relative to surface crosssectional area (A) at Ist-drder sites where it averaged 1.2 x A, compared with 0.6 x A and 0.1 x A in unconstrained and constrained 5th-order sites, respectively. Where measured, lateral discharge inputs per metre of stream length ranged from 1.9% of instream discharge in Ist-order streams to 0.05% of instream discharge at 5th-order sites. Our results show that surface water exchange with storage zones is rapid and extensive in steep headwater streams and less extensive but still significant at 3rd- through 5th-order sites. An understanding of relationships between stream morphology, storage zone size, and extent of interactions between surface and subsurface waters will assist comparisons of solute dynamics in physically diverse streams.

D'Angelo, D.J., S.V. Gregory, and L.R. Ashkeans. 1997. Physical and biological linkages within a stream geomorphic hierarchy: a modeling approach. Journal of the North American Benthological Society. 16(3): 480-502.

Abstract
Geology and precipitation interact to determine the geomorphology of a stream basin. We propose that stream geomorphology in turn interacts with sunlight, air temperature, precipitation, and geology to produce a distribution of environmental drivers (incident radiation, discharge, water temperature, nutrients) that is largely responsible for determining the distribution of organisms in streams. GEOMOD, a physically explicit stream ecosystem model, was designed to examine this proposal. The model has a geomorphically based hierarchical structure with basin, reach, and channel-unit levels of resolution. We used GEOMOD: 1) to simulate annual cycles of the biota in 3rd- and 5th-order stream sections at the basin level of resolution and 2) to predict organism distributions at the reach and channel-unit level of resolution. Stream physical structure and the 4 environmental drivers were the only factors that differed among the sites. Data from two 150-m sections of 3rd-order Mack Creek (one in old-growth and the other in clear-cut forest) and from a 1.5-km section of 5th-order Lookout Creek in the Cascade mountains of Oregon were used to parameterize the physical structure and initial standing crops and calibrate the drivers. Uniform parameters were determined by curve-fitting. GEOMOD simulated annual magnitudes and cycles for abiotic (e.g., channel dimensions, fine particulate organic matter) and biotic (e.g., algae, invertebrates, fish) variables in Mack and Lookout creeks. With explicit parameterization of reach and channel-unit sequences, GEOMOD also predicted the distribution of organisms among channel units and reaches. Fish distributions were accurately predicted at the reach scale, while algal-invertebrate interactions and scouring effects became clear only when examined at the channel-unit level. These results demonstrate that organism distributions and interactions in highly structured streams such as those in the Pacific Northwest region of the USA can be effectively simulated with a physically explicit model. Although more complicated to design and parameterize than a uniform physical representation, a physical explicit model can be tailored to represent a wide variety of stream types.

Daly, C., Slater, M. E., Roberti, J. A., Laseter, S. H. and Swift, L. W. (2017), High-resolution precipitation mapping in a mountainous watershed: ground truth for evaluating uncertainty in a national precipitation dataset. Int. J. Climatol, 37: 124–137. doi:10.1002/joc.4986

Abstract
A 69-station, densely spaced rain gauge network was maintained over the period 1951–1958 in the Coweeta Hydrologic Laboratory, located in the southern Appalachians in western North Carolina, USA. This unique dataset was used to develop the first digital seasonal and annual precipitation maps for the Coweeta basin, using elevation regression functions and residual interpolation. It was found that a 10-m elevation grid filtered to an approximately 7-km effective wavelength explained the most variance in precipitation (R2 =0.82–0.95). A ‘dump zone’ of locally high precipitation a short distance downwind from the mountain crest marking the southern border of the basin was the main feature that was not explained well by the precipitation–elevation relationship. These data and maps provided a rare ‘ground-truth’ for estimating uncertainty in the national-scale Parameter-elevation Relationships on Independent SlopesModel (PRISM) precipitation grids for this location and time period. Differences between PRISM and ground-truthwere comparedwith uncertainty estimates produced by the PRISMmodel and cross-validation errors. Potential sources of uncertainty in the national PRISM grids were evaluated, including the effects of coarse grid resolution, limited station data, and imprecise station locations. The PRISM national grids matched closely (within 5%) with the Coweeta dataset. The PRISM regression prediction interval, which includes the influence of stations in an area of tens of kilometres around a given location, overestimated the local error at Coweeta (12–20%). Offsetting biases and generally low error rates made it difficult to isolate major sources of uncertainty in the PRISM grids, but station density and selection, and mislocation of stations were identified as likely sources of error. The methods used in this study can be repeated in other areas where high-density data exist to gain a more comprehensive picture of the uncertainties in national-level datasets, and can be used in network optimization exercises.

Darke, A.K., and M.R. Walbridge. 2000. Al and Fe Biogeochemistry in a floodplain forest: Implications for P retention. Biogeochemistry. 51: 1-32.

Abstract
We examined spatial and temporal variations in soil chemistry in a floodplain forest landscape to determine the effects of flooding on aluminum (Al) and iron (Fe) oxide biogeochemistry and inorganic phosphorus (Pi) sorption capacity. When previously sorbed (Pi) sorption capacity. When previously sorbed Pi was considered, the sorption capacities of floodplain and adjacent upland soils were comparable, suggesting that floodplain soils represent a second line of defense protecting downstream aquatic ecosystems from agricultural run-off. Pi sorption capacity was highly correlated with oxalate-extractable Al (Alo)(rs= 0.78); Alo and percent organic matter (OM) were also highly correlated (rs=0.72), suggesting the importance of OM-Al complexes in these soils. The correlation of oxalate-extractable Fe (Feo) with OM (rs = 0.64) was improved (rs= 0.80) by removing lower elevation (swale) soils, suggesting that flooding inhibits the association of Feo with OM. Fe oxide crystallinity decreased during seasonal flooding, but total extractable Fe did not change significantly. Fe solubilized during flooding was either replaced by sediment deposition (252 + 3 mmol kg ˉ+ yr ˉ+), and/or reprecipitated locally. Al oxide crystallinity also decreased during flooding due to a significant decline in NaOH-extractable Al (AlN). AlN concentrations subsequently returned to pre-flooding levels, but sediment Al inputs (57 + 3 mmol kg ־+ yr ˉ+), were insufficient to account for this recovery. Observed Fe transformations suggest the importance of flooding-induced declines in soil redox potential to Fe biogeochemistry; observed Al transformations suggest the importance of complexation reactions with soil OM to Al biogeochemistry in this floodplain forest.

Davidson, E.A., and W.T. Swank. 1986. Environmental parameters regulating gaseous nitrogen losses from two forested ecosystems via nitrification and denitrification. Applied and Environmental Microbiology 52(6): 1287-1292.

Abstract
Gaseous N losses from disturbed and forested watersheds at Coweeta were studied by in situ N2O diffusion measurements and laboratory incubations. Soil temperature, percent base saturation, and water-filled pore space accounted for 43% of the variation of in situ N2O diffusion measurements. Nitrifying activity, ambient NO3, and nitrification N2O were positively correlated with percent base saturation. Differences between watersheds in soil N substrate caused by leguminous black locust in the disturbed watershed were confounded with differences in soil acidity. Gaseous N losses from well-drained midslope and toeslope landscape positions were minor relative to other N transformations. Favorable conditions for denitrification occurred at a poorly drained site near the stream.

Davidson, E.A., and W.T. Swank. 1987. Factors limiting denitrification in soils from mature and disturbed southeastern hardwood forests. Forest Science 33(1): 135-144.

Abstract
The relative importance of O2, NO3, organic carbon and acidity on denitrification was studied in a full 26 factorial experiment. Soils were collected from two forested watersheds and at two slope positions. Combinations of four incubation treatments were applied. An ANOVA of N2O production during 24-hr aerobic incubations under 10 kPa acetylene revealed that all main effects were significant. Flooding with H2O increased N2O production by three orders of magnitude in disturbed soils exhibiting high ambient NO3. Both flooding and NO3 amendment were necessary to increase N2O production in reference soils exhibiting low ambient NO3. Glucose amendment increased N2O production in the mineral soil sampled at 6-15 cm depth more than in the 0-6 cm sample. Carbon limitation is probably unimportant for denitrification in surface horizons at Coweeta, but C-limitation occurs with increasing soil depth. Although acid treatment had a minor inhibitory effect on denitrification rates, acid forest soils apparently support denitrifier populations capable of appreciable NO3 reduction.

Davidson, E.A., and W.T. Swank. 1990. Nitrous oxide dissolved in soil solution: an insignificant pathway of nitrogen loss from a southeastern hardwood forest. Water Resources Research 26(7): 1687-1690.

Abstract
Nitrous oxide is soluble and can accumulate in soil solution when gaseous diffusion is restricted. The importance of N losses via degassing of N2O from groundwater entering surface streams is unknown. Measurements of N2O in soil solution revealed patterns of seasonal and spatial variation that were consistent with ecosystem regulation of denitrification. The highest concentrations were observed in the riparian zone in May, when soil NO3, temperature, and moisture were conducive for denitrification. At each of the other sample dates and sites, at least one of these factors appeared to prevent significant N2O accumulationin soil solution. Extrapolation of the highest observed N2O concentrations toan annual basis corresponded to a loss of only 56 g N/ha/yr. Denitrification in the riparian zone may be an important fate of N in this hardwood forest, but N2O in soil solution does not appear to be a significant pathway of N loss. Extrapolation of the highest calculated losses from soil solution to the global area occupied by hardwood forest indicates that this source of N2O is insignificant for global atmospheric budgets.

Davidson, E.A., L.F. Galloway, and M.K. Strand. 1987. Assessing available carbon: comparison of techniques across selected forest soils. Communication In Soil Science Plant Analogy 18(1): 45-64.

Abstract
Several techniques for assessing available C have been described in the literature, but none has become standard. Four methods, (1) mineralizable C, (2) cold water soluble C, (3) boiling water extractable C, and (4) total C, were compared to each other and to a denitrification potential bioassay of C availability. These comparisons were made across selected forest soils which exhibited wide ranges of textural composition and organic C content and which ranged in acidity from pH 3.1 to 5.4. None of the procedures studied provides an unequivocal measure of available C. Nevertheless, mineralizable C appears promising as a standard procedure because: (1) it measured C presumably mineralized by microorganisms, (2) it proved effective in predicting denitrification potential under incubation conditions that were mostly C limited, and (3) it was the simplest of the procedures examined.

Davidson, E.A., M.K. Strand, and L.F. Galloway. 1985. Evaluation of the Most Probable Number Method for Enumerating Denitrifying Bacteria. Soil Science Society of America Journal. 49(3): 642-645.

Abstract
Most probable number (MPN) enumerations of denitrifying bacteria were conducted on an agricultural soil (pH 6.6) and a forest soil (pH 5.6), in both neutral (pH 6.8) and acid (pH 5.6) media. The neutral medium yielded higher enumerations for both soils and, therefore, appears to be optimal, even for denitrifiers present in acid soils. Enzyme activity assays and MPN enumerations of seven soil samples were weakly correlated (r = 0.71; p = 0.07). One soil exhibited a high MPN enumeration, but had no detectable denitrifying enzyme activity. While the enzyme assay indexes denitrification potential of soils under the environmental conditions at the time of sampling, the MPN enumeration indexes the denitrifying capability of the populations inhabiting soils. A population's denitrifying capability is related to its size, but other factors which might also influence MPN enumerations are discussed. Precise incubation time was critical in the MPN procedure. Delays of 2h affected the scoring results. Populations in some of the incubation tubes appeared to be in a dynamic growth phase at the end of the 14-d incubation period. Inconsistencies in incubation duration could confound comparisons among soils. Despite inherent flaws and disadvantages, the MPN procedure may be appropriate for certain research objectives as an index of a population's denitrifying capacity. Recommendations and cautions are offered.

Davidson, E.A., W.T. Swank, and T.O. Perry. 1986. Distinguishing between nitrification and denitrification as sources of gaseous nitrogen production in soil. Applied and Environmental Microbology 52(6): 1280-1286.

Abstract
Denitrification and nitrification can occur simultaneously in the same soil aggregate. A technique which exploits the differential sensitivity of these processes to C2H2 inhibition is proposed for distinguishing among gaseous N losses from soils. Denitrification N2O was estimated from laboratory incubations where nitrification was inhibited by 10-Pa C2H2. Nitrification N2O was estimated from the difference between NS production under no C2H2 and that determined for denitrification. Denitrification N2 was estimated from the difference between N2O production under 10-kPa C2H2 and that under 10 Pa. Laboratory estimates were significantly correlated with in situ N2O measurements made during a 10-month period in two forested watersheds. Nitrous oxide production by nitrification was most important on well-drained sites of a disturbed watershed where ambient NO3 was high. In contrast, denitrification N2O was most important on poorly drained sites near the stream.

Davis J. M., Rosemond, A.D., Small, G.E., 2011. Increasing donor ecosystem productivity decreases terrestrial consumer reliance on a stream resource subsidy. Oecologia 167:3, Nov. 2011, p. 821-834 DOI 10.1007/s00442-011-2026-9

Abstract
Because nutrient enrichment can increase ecosystem productivity, it may enhance resource flows to adjacent ecosystems as organisms cross ecosystem boundaries and subsidize predators in recipient ecosystems. Here, we quantified the biomass and abundance of aquatic emergence and terrestrial spiders in a reference and treatment stream that had been continuously enriched with nitrogen and phosphorus for 5 years. Because we previously showed that enrichment increased secondary production of stream consumers, we predicted that aquatic emergence flux would be higher in the treatment stream, subsequently increasing the biomass and abundance of terrestrial spiders. Those increases were predicted to be greatest for spiders specializing on aquatic emergence subsidies (e.g., Tetragnathidae). By adding a 15Nstable isotope tracer to both streams, we also quantified nitrogen flow from the stream into the riparian community. Emergence biomass, but not abundance, was higher in the treatment stream. The average body size of emerging adult insects and the relative dominance of Trichoptera adults were also greater in the treatment stream. However, spider biomass did not differ between streams. Spiders also exhibited substantially lower reliance on aquatic emergence nitrogen in the treatment stream. This reduced reliance likely resulted from shifts in the body size distributions and community composition of insect emergence that may have altered predator consumption efficiency in the treatment stream. Despite nutrient enrichment approximately doubling stream productivity and associated cross ecosystem resource flows, the response of terrestrial predators depended more on the resource subsidy’s characteristics that affected the predator’s ability to capitalize on such increases.

Davis, Andrew K., Cecala, K. (2010) Intraerythrocytic rickettsial inclusions in Ocoee salamanders (Desmognathus ocoee): prevalence, morphology, and comparisons with inclusions of Plethodon cinereus. Parasitol Research, 107:363-367. DOI 10.1007/s00436-010-1869-z

Abstract
Reports of an unusual intraerythrocytic pathogen in amphibian blood have been made for decades; these pathogens appear as membrane-bound vacuoles within erythrocytes. It is now understood that the pathogen is a Rickettsia bacteria, which are obligate intracellular parasites, and most are transmitted by arthropod vectors. In an effort to further understand the host range and characteristics of this pathogen, we examined 20 Ocoee salamanders (Desmognathus ocoee) from a site in southwest North Carolina for the presence of rickettsial inclusions and report the general characteristics of infections. Seven individuals (35%) were infected, and this level of prevalence was consistent with all other members of this genus examined to date. In contrast, infections within the genus Plethodon tend to occur in less than 10% of individuals, based on review of the literature. The difference could be related to the semi-aquatic nature of Desmognathus salamanders versus the completely terrestrial Plethodon. It is also possible that both groups are hosts to different types of rickettsial bacteria, since the inclusions found here only vaguely resembled those found recently in red-backed salamanders (Plethodon cinereus). Inclusions in Ocoee salamanders measured 4 microm in diameter on average, and most cells (88%) only had one inclusion. Of all infected individuals, inclusions occurred in approximately 3% of erythrocytes. Similar to that found in red-backed salamanders, infected hosts were significantly larger than non-infected. Future investigations into the nature of this unusual parasite of amphibians would help to further our understanding of its life cycle and transmission.

Davis, J. M., A. D. Rosemond, S. L. Eggert, W. F. Cross, and J. B. Wallace. 2010. Nutrient enrichment differentially affects body sizes of primary consumers and predators in a detritus-based stream. Limnology and Oceangraphy, 55(6): 2305-2316.

Abstract
We assessed how a 5-yr nutrient enrichment affected the responses of different size classes of primary consumers and predators in a detritus-based headwater stream. We hypothesized that alterations in detritus availability because of enrichment would decrease the abundance and biomass of large-bodied consumers. In contrast, we found that 2 yr of enrichment increased the biomass and abundance of all consumers regardless of body size. Furthermore, during the fourth and fifth year of enrichment, the abundance and biomass of largebodied primary consumers continued to increase, while small-bodied primary consumers returned to pretreatment levels. The size structure of a dominant primary consumer (Pycnopsyche spp.) also shifted during the 5-yr enrichment: its average and maximum individual body size increased in the treatment stream compared with the reference stream. Positive enrichment effects also occurred on small-bodied predators, but not on large-bodied predators. Thus, enrichment increased prey body size, but these positive effects on large prey did not propagate up to higher trophic levels to affect large predators. Because consumer body size can be an important species-specific trait determining population dynamics and ecosystem processes, these observed shifts in consumer size distributions suggest a potentially important pathway for global increases in nutrient enrichment to alter stream structure and function.

Davis, J.M., Rosemond, A.D., Eggert, S.L., Crossa, W.F., Wallace, J.B. 2009. Long-term nutrient enrichment decouples predator and prey production. PNAS. 107(1): 121-126

Abstract
Increased nutrient mobilization by human activities represents one of the greatest threats to global ecosystems, but its effects on ecosystemproductivity can differ depending onfoodwebstructure. When this structure facilitates efficient energy transfers to higher trophic levels, evidence from previous large-scale enrichments suggests that nutrients can stimulate the production of multiple trophic levels. Here we report results from a 5-year continuous nutrient enrichment of a forested stream that increased primary consumer production, but not predator production. Because of strong positive correlations between predator and prey production (evidence of highly efficient trophic transfers) under reference conditions, we originally predicted that nutrient enrichment would stimulate energy flow to higher trophic levels. However, enrichment decoupled this strong positive correlation and produced a nonlinear relationship between predator and prey production. By increasing the dominance of large-bodied predator-resistant prey, nutrient enrichment truncated energy flow to predators and reduced food web efficiency. This unexpected decline in food web efficiency indicates that nutrient enrichment, a ubiquitous threat to aquatic ecosystems, may have unforeseen and unpredictable effects on ecosystem structure and productivity.

Davis, J.P., B. Haines, D. Coleman, and R. Hendrick. 2004. Fine root dynamics along an elevational gradient in the southern Appalachian mountains, USA. Forest Ecology and Management. 187: 19-34.

Abstract
Attributes of fine roots (<2.0 mm diameter) were quantified in five southern Appalachian plant communities along an elevation gradient. These Attributes include the seasonal dynamics of fine root mass and length, the depth distribution of fine roots, fine root width and, most importantly, the annual appearance and disappearance of fine roots. The principal objectives of this study were two-fold: (1) to compare these attributes of fine roots between plant communities and (2) to compare the results of the two methods used to quantify the attributes: (1) harvesting roots from forest soil with soil cores and (2) photographing roots growing against the windows of minirhizotron boxes. The plant communities that were sampled are characteristic of the region and are designated as follows from lowest elevation (782 m) to highest elevation (1347 m): (1) xeric ridge, (2) hardwoods, (3) low elevation mixed oak, (4) high elevation mixed oak, and (5) northern hardwoods. Fine root mass varies seasonally in this temperate region with lowest and highest mass in the spring and autumn, respectively, Fine root mass and fine root mass appearance were lowest in the cove hardwood community and highest in the low elevation mixed oak community. The total length of fine roots was highest in the xeric ridge community and lowest in the low elevation mixed oak community. The high total root length in the xeric ridge community was due to the presence of an exceptionally dense mat of very fine roots found there. The width of these roots was significantly less than that of roots on all other plots. Subsequent regression illustrates tow strong patterns in the data. First, fine root mass, fine root mass appearance and leaf production were positively correlated. Second, fine root length and soil moisture were negatively correlated. The accumulation of root mass in these communities was linked to overall site productivity and the development of root length in response to moisture stress. Only the timing of root growth initiation was related to elevation and the associate parameter of soil temperature. The best estimates of fine root appearance and disappearance were generated by harvesting roots rather than photographing them. Some methodological problems with root photography implemented in this study are addressed.

Davis, R J., D.C. Guynn Jr., and B.D. Hyder. 1994. Feasibility of using tribromoethanol to recapture wild turkeys. Wildlife Society Bulletin 22(3): 496-500.

Abstract
TBE (tribromoethanol), a drug added to shelled corn bait, was used to capture wild turkeys for measurement and attachment of tracking radio transmitters. Response to TBE was noted for forty birds previously captured using TBE. Eighteen birds returned to bait sites, but only 4 took the treated bait and only in the year after initial capture. Experienced birds were less likely to take the bait and were observed warning other birds after sampling the treated bait. Six mortalities occurred due to overdosing when part of the flock refused the bait. TBE is not recommended for retrapping of wild turkey .

Day, F.P., and C.D. Monk. 1974. Vegetation patterns on a southern Appalachian watershed. Ecology 55: 1064-1074.

Abstract
The vegetation on a relatively undisturbed hardwood forest watershed at Coweeta was sampled, and estimates of density, basal area, and above-ground biomass were computed. These vegetational parameters and five topographic variables were used to analyze site-species relationships on the watershed. The primary analytical techniques used were correlation analysis and principal components ordination. Major changes in the vegetation since the introduction of chestnut blight were also examined. Significant correlations were found between 13 major species and one or more of the topographic variables. Distance from the stream, distance from the water divide and elevation, were the important topographic factors determining species distribution at Coweeta.

Day, F.P., and C.D. Monk. 1977. Net primary production and phenology on a Southern Appalachian watershed. American Journal of Botany 64: 1117-1125.

Abstract
The major objective of the study was to measure above-ground net primary production (NPP) seasonally and relate it to phenological activity in a hardwood forest at Coweeta. NPP was estimated as the increase in biomass, estimated from regression equations on diameter. Diameter increases were measured by vernier tree bands. Phenological observations were made on bud break, leaf emergence, flowering, mature fruit, leaf senescence, and leaf fall. The species studied intensively were Acer rubrum, Quercus prinus, Carya glabra, Cornus florida, and Liriodendron tulipifera.

Day, F.P., and C.D. Monk. 1977. Seasonal nutrient dynamics in the vegetation on a Southern Appalachian watershed. American Journal of Botany 64: 1126-1139.

Abstract
Nutrient dynamics in vegetation play an important role in determining the circulation and storage of nutrients in an ecosystem. The major objectives of this study were to estimate the plant nutrient pools on a hardwood forest watershed at Coweeta, on a seasonal basis and to relate any observed trends to seasonal productivity and phenology. Major conclusions of the study were (1) individual species and different plant components have nutrient storage-pool turnover times ranging from one year to several hundred years. Canopy species are important in long- and short-term nutrient cycles. (2) Even though most of the annual nutrient uptake is recycled the same season, the total accumulation of nutrients is considerable in a mature forest stand.

DeHaven, J.E., Stouder, D.J., Ratajczak, R., Welch, T.J., Grossman, G.D. 1992. Reproductive timing in three southern Appalachian stream fishes. Ecology of Freshwater Fish, 1: 104-111

Abstract
We quantified the reproductive biology of mottled sculpin (Cottus bairdi), rosyside dace (Clinostomus funduloides) and longnose dace (Rhinichthus cataractae) in Coweeta Creek, North Carolina, USA, a fifth order stream. These species are abundant in coldwater streams through out the southern Appalachian mountains, the southernmost limit of their range. We collected fishes from Coweeta Creek every second month (between July 1984 and January 1986) and quantified the seasonal reproductive cycles of females, using both histological techniques and the relative gonadal index (RGI). Both techniques indicated that I) C. bairdi reproduced between March and May, 2) CI. funduloides spawned between May and August and 3) R. cataractae were reproductively active between June and July. These conclusions were supported by the following: 1) the presence of reproductive coloration, 2) gravid females, 3) courtship displays, 4) the presence of nest-guarding C. bairdi males and 5) the timing of young-of-the-year recruitment. The reproductive characteristics of these 3 species were correlated with different environmental variables. The mean monthly RGI values for both C. bairdi and R. cataractae were inversely correlated with both maximum and minimum daily water temperatures. The mean RGI values for C. bairdi also were negatively correlated with photoperiod, whereas the values for R. cataractae and CI. funduloides were positively correlated with the change in daily photo period.

Dehring, C. A., C. A. Depken II. 2010. Sharing the Burden of Water Supply Protection. Regulation: 36-40.

Abstract
A sufficient supply of freshwater is critical to human survivability and biodiversity. Much of the recent decline in freshwater biodiversity and overall freshwater ecosystem health is attributable to land use change. Land use practices that influence freshwater include agriculture, forestry, mining, industrialization, and urbanization. While agriculture has historically been viewed as the land use practice most likely to adversely affect water quality, urban development is now seen as the greatest threat to freshwater ecosystems in certain parts of the United States.

Dehring, C.A., Chamblee, J.F., Colwell, P.F., Dehring, C. and Depken, C. 2011. The Effect of Conservation Activity on Surrounding Land Prices. Land Economics. 87(3):452-472.

Abstract
This paper presents an empirical analysis of the structure of land prices both before and after land conservation occurs. Using data describing 12 years of vacant land transactions in Buncombe County, North Carolina, we find that fee simple conservations, as opposed to conservation easements, occur in higher-priced areas, but that lower-valued parcels within these areas are selected for conservation. We find positive price effects from land conservation of 46%. This premium declines with distance from the conserved parcel but does so to a lesser extent with easements, perhaps suggesting the market�s perception that conservation easements are more permanent than parcels conserved in fee. (JEL H23, Q51)

Demi, L.M., J.P. Benstead, A.D. Rosemond, and J.C. Maerz. 2018. Litter P content drives consumer production in detritus-based streams spanning an experimental N:P gradient. Ecology. 99:347-359. 10.1002/ecy.2118

Abstract
Ecological stoichiometry theory (EST) is a key framework for predicting how variation in N:P supply ratios influences biological processes, at molecular to ecosystem scales, by altering the availability of C, N, and P relative to organismal requirements. We tested EST predictions by fertilizing five forest streams at different dissolved molar N:P ratios (2, 8, 16, 32, 128) for two years and tracking responses of macroinvertebrate consumers to the resulting steep experimental gradient in basal resource stoichiometry (leaf litter %N, %P, and N:P). Nitrogen and P content of leaf litter, the dominant basal resource, increased in all five streams following enrichment, with steepest responses in litter %P and N:P ratio. Additionally, increases in primary consumer biomass and production occurred in all five streams following N and P enrichment (averages across all streams: biomass by 1.2×, production by 1.6×). Patterns of both biomass and production were best predicted by leaf litter N:P and %P and were unrelated to leaf litter %N. Primary consumer production increased most in streams where decreases in leaf litter N:P were largest. Macroinvertebrate predator biomass and production were also strongly positively related to litter %P, providing robust experimental evidence for the primacy of P limitation at multiple trophic levels in these ecosystems. However, production of predatory macroinvertebrates was not related directly to primary consumer production, suggesting the importance of additional controls for macroinvertebrates at upper trophic positions. Our results reveal potential drivers of animal production in detritus-based ecosystems, including the relative importance of resource quality vs. quantity. Our study also sheds light on the more general impacts of variation in N:P supply ratio on nutrient-poor ecosystems, providing strong empirical support for predictions that nutrient enrichment increases food web productivity whenever large elemental imbalances between basal resources and consumer demand are reduced.

Deshefy, G.S. 1979. Predator escape behavior by fall cankerworm larvae, Alsophila pometaria (Lepidoptera: Geometridae). Entomological News 90: 145-146.

Abstract
Silk emission and dropping behavior in larvae of the fall cankerworm, Alsophila pometaria, enable the species to escape predation and ultimately reestablish contact with its tree host.

Dharmadi, Sandra N., Elliott, Katherine J., Miniat, Chelcy F. (2019) Lack of forest tree seedling recruitment and enhanced tree and shrub growth characterizes post-Tsuga canadensis mortality forests in the southern Appalachians, Forest Ecology and Management. Forest Ecology and Management, 440:122-130, https://doi.org/10.1016/j.foreco.2019.03.024

Abstract
The loss of Tsuga canadensis from invasion by hemlock woolly adelgid (Adelges tsugae, HWA) has altered ecosystem structure and function in forests across the eastern United States. In southern Appalachian forests, T. canadensis co-occurred with hardwood species and an evergreen Rhododendron maximum shrub layer in riparian and cove positions. In this region, HWA infestation was detected in 2003, with mortality reaching 97% by 2014. In this study we examined responses of light, soil moisture, tree seedling density, and overstory and understory vegetation growth from 2004 to 2014 following HWA infestation and mortality of T. canadensis. We hypothesized that seedling recruitment and vegetation growth would continue to increase over time as observed with initial trends reported through 2009, and that species that associate with ectomycorrhizal (ECM) fungi may benefit more than those that do not due to the pulse of organic material in these stands from dead T. canadensis trees. Light transmission measured at 1m above the ground increased from 2006 to 2009, but gradually decreased from 2015 to 2017. Basal area of overstory non-Tsuga trees increased only marginally, and there was no recruitment of tree seedlings to the overstory size class, even though seedling density of deciduous species increased initially. Increased basal area and stem density of R. maximum may explain the light and seedling responses, as this species can inhibit tree seedling recruitment by limiting light and nutrients. Overstory species with the highest basal area increment (BAI) in the post-T. canadensis stands were Pinus rigida, Betula lenta and Quercus coccinea, which all associate with ECM fungi. However, not all ECM tree species grew significantly more following T. canadensis mortality compared to pre-mortality growth rates—only those ECM species that had high growth rates prior to mortality did. After a decade, growth of both overstory trees and R. maximum has not compensated for the loss of T. canadensis. Active management of R. maximum, which may involve the removal of the evergreen shrub and soil organic layer, may be required to allow for diverse tree seedling recruitment; and subsequently, restore riparian forest structure, diversity, and function.

Diamond, S.J., R.H. Giles Jr., R.L. Kirkpatrick, and G.J. Griffin. 2000. Hard Mast Production Before and After the Chestnut Blight. Southern Journal of Applied Forestry. 24(4): 196-201.

Abstract
We estimated hard mast production of a Southern Appalachian forest for two 10 year intervals: one before and one, 35 years after, the chestnut blight fungus (Cryphonectria parasitica) (Murr.) Barr, had killed all mature chestnut trees. The basal area of hard mast-producing trees in the postblight forest was 28% less than in the preblight forest. The estimate of hard mast output was 34% less after the chestnut blight. Postblight production was less than preblight production for 8 of 10 years. During 5 of these years, postblight production was only 5-27% of preblight production. Annual preblight mast production was relatively stable, whereas annual postblight production fluctuated substantially. Our findings suggest that the loss of mature chestnuts (Castanea dentata) markedly reduced the Southern Appalachian forest's carrying capacity for certain wildlife species.

Dietze, M. and J. S. Clark. 2007. Rethinking gap dynamics: the impact of damaged trees and sprouts. Ecological Monographs 78:331-347.

Abstract
Understanding the manner in which changes in disturbance regimes will affect forest biodiversity is an important goal of global change research. Prevailing theories of recruitment after disturbance center on the role of pioneer species; predictions of forest biodiversity focus almost exclusively on dispersal and shade tolerance while vegetative reproduction is virtually omitted from models and serious discussions of the topic. However, the persistence of live damaged trees increases understory shade, generates fine-scale environmental heterogeneity, and moderates ecosystem responses to damage, while the sprouting of damaged trees offers a shortcut to reestablishment of the canopy. While a number of studies document snapshots of post-disturbance vegetative reproduction, we lack an understanding of the underlying demographic processes needed in order to both comprehend and predict observed patterns. In this study we quantify the abundance, competitive ability, and interspecific variability of vegetative reproduction in 18 replicated experimental gaps in the southern Appalachians and Carolina Piedmont, USA, in order to assess the potential role of sprouting in driving gap dynamics.

Dietze, M.C., Clark, J.S. 2008. Changing the Gap Dynamics Paradigm: Vegetative Regeneration Control on Forest Response to Disturbance. Ecological Monographs 78(3) 331-347.

Abstract
Understanding the manner in which changes in disturbance regimes will affect forest biodiversity is an important goal of global change research. Prevailing theories of recruitment after disturbance center on the role of pioneer species; predictions of forest biodiversity focus almost exclusively on dispersal and shade tolerance while vegetative reproduction is virtually omitted from models and serious discussions of the topic. However, the persistence of live damaged trees increases understory shade, generates fine-scale environmental heterogeneity, and moderates ecosystem responses to damage, while the sprouting of damaged trees offers a shortcut to reestablishment of the canopy. While a number of studies document snapshots of post-disturbance vegetative reproduction, we lack an understanding of the underlying demographic processes needed in order to both comprehend and predict observed patterns. In this study we quantify the abundance, competitive ability, and interspecific variability of vegetative reproduction in 18 replicated experimental gaps in the southern Appalachians and Carolina Piedmont, USA, in order to assess the potential role of sprouting in driving gap dynamics. Annual rates of damaged adult survival, sprout initiation, growth, and mortality were monitored over four years and compared to the performance of gap-regenerating saplings. Recruitment from sprouts was found to constitute 26–87% of early gap regeneration and forms the dominant pathway of regeneration for some species. Sprouts from recently damaged trees also grow significantly faster than the saplings with which they compete. For all measured demographic rates (damaged tree survival, sprout initiation, number, growth, and survival) differences among species are large and consistent across sites, suggesting that vegetative reproduction is an important and non-neutral process in shaping community composition. Sprouting ability does not correlate strongly with other life-history trade-offs, thus sprouting potentially provides an alternate trait axis in promoting diversity.

Dietze, M.C., Wolosin, M.S., Clark, J.S. 2008. Capturing diversity and interspecific variability in allometries: A hierarchical approach. Forest Ecology and Management 256: 1939-1948

Abstract
There is growing recognition of the role of mechanistic scaling laws in shaping ecological pattern and process. While such theoretical relationships explain much of the variation across large scales, at any particular scale there is important residual variation that is left unexplained among species, among individuals within a species, and within individuals themselves. Key questions remain on what explains this variability and how we can apply this information in practice, in particular to produce estimates in high-diversity systems with many rare and under-sampled species. We apply hierarchical Bayes statistical techniques to data on crown geometry from diverse temperate forests in order to simultaneously model the differences within and among species. We find that tree height, canopy depth, and canopy radius are affected by both successional stage and wood mechanical strength, while tree height conforms to the predicted 2/3 power relationship. Furthermore, we show that hierarchical modeling allows us to constrain the allometries of rare species much more than traditional methods. Finally, crown radius was shown to vary substantially more within individuals than among individuals or species, suggesting that the capacity for local light foraging and crown plasticity exerts the dominant control on tree crowns.

Diez, J.M. 2007. Hierarchical patterns of symbiotic orchid germination linked to adult proximity and environmental gradients. Journal of Ecology. 95: 159-170.

Abstract
(1) The recruitment stage can be critical in determining plant population dynamics, as juveniles encounter a range of abiotic and biotic stressors in the environments where they land after dispersal, and often experience high mortality rates. Although both abiotic and biotic constraints on recruitment are often assumed to operate at multiple scales, these relationships are rarely quantified in ways that enable prediction of recruitment dynamics across environmental gradients. (2) In plants such as orchids, an important bottleneck on recruitment may arise from an obligate dependence on mycorrhizal fungi in order to reach photosynthetic stage. Very little is known, however, about the factors controlling the distribution of the fungi or how fungal distributions may constrain orchid recruitment and distributions. (3) In this study, seed introduction experiments were used to test for relationships between symbiotic germination success of an orchid, Goodyera pubescens, and both proximity to adult orchids and soil abiotic conditions. Experiments were linked to ongoing demographic monitoring across a large environmental gradient to place patterns of germination better in the context of longer-term demographic patterns. (4) A hierarchical Bayesian statistical framework was used to evaluate explicitly how recruitment varies across scales and how this variation is explained by key abiotic variables. This framework was further utilized to link hypothesis testing to model building, and thereby improve our ability to make predictions across a range of environmental conditions. (5) At a microsite scale (< 4 m2) strong evidence was found for decreasing germination success further from adult plants. At distances greater than 1 m from adults, increased germination success was associated with higher soil moisture, higher organic content and lower pH, although the strength of these relationships varied regionally. Patterns of symbiotic germination success were also highly correlated with observed recruitment patterns at the population level. (6) Explicitly linking plant recruitment to underlying abiotic gradients and key biotic interactions using a hierarchical, predictive modelling framework is essential for understanding basic plant population processes and building capacity to make predictions of how species and communities may respond to environmental changes.

Diez, J.M., and H.R. Pulliam. 2007. Hierarchical analysis of species distributions and abundance across environmental gradients. Ecology 88(12): 3144-3152.

Abstract
Abiotic and biotic processes operate at multiple spatial and temporal scales to shape many ecological processes, including species distributions and demography. Current debate about the relative roles of niche-based and stochastic processes in shaping species distributions and community composition reflects, in part, the challenge of understanding how these processes interact across scales. Traditional statistical models that ignore autocorrelation and spatial hierarchies can result in misidentification of important ecological covariates. Here, we demonstrate the utility of a hierarchical modeling framework for testing hypotheses about the importance of abiotic factors at different spatial scales and local spatial autocorrelation for shaping species distributions and abundances. For the two orchid species studied, understory light availability and soil moisture helped to explain patterns of presence and abundance at a microsite scale (<4 m2), while soil organic content was important at a population scale (<400 m2). The inclusion of spatial autocorrelation is shown to alter the magnitude and certainty of estimated relationships between abundance and abiotic variables, and we suggest that such analysis be used more often to explore the relationships between species life histories and distributions. The hierarchical modeling framework is shown to have great potential for elucidating ecological relationships involving abiotic and biotic processes simultaneously at multiple scales.

Diez, Jeffrey M., Itamar Giladi, Robert Warren and H. Ronald Pulliam 2014. Probabilistic and Spatially Variable Niches Inferred from Demography. In Journal of Ecology, pp. 1-6, online publication.

Abstract
1. Mismatches between species distributions and habitat suitability are predicted by niche theory and have important implications for forecasting how species may respond to environmental changes. Quantifying these mismatches is challenging, however, due to the high dimensionality of species niches and the large spatial and temporal variability in population dynamics. 2. Here, we explore how probabilistic assessments of habitat suitability based on demographic models may be used to better bridge niche theory and population dynamics. We use integral projection models (IPMs) to predict population growth rates for a terrestrial orchid in response to environmental variables. By parameterizing these IPMs with hierarchical models, we develop a spatially variable measure of a species’ demographic niche, which can then be compared against its distribution to test ideas about what factors control a species’ distribution. 3. We found that demographic suitability of sites was not well correlated with the orchid’s distribution at local scales, with many absences from microsites of high predicted suitability and occurrences in sites with low predicted suitability. However, at the population scale, abundance was positively correlated with demographic suitability of the sites. These results are consistent with dispersal limitation and source–sink dynamics at small scales but stronger distribution-suitability matching at larger landscape scales. 4. Synthesis. The relationships between species distributions and demographic performance underlie basic niche theory and have important implications for predicting responses to a changing environment. The complexities of these relationships will require approaches that can encapsulate what we know in probabilistic terms and allow for spatially varying niche relationships.

Dighton, J., and D.C. Coleman. 1992. Phosphorus relations of roots and mycorrhizas of Rhododendron maximum L. in the southern Appalachians, North Carolina. Mycorrhiza. 1:175-184.

Abstract
The mycorrhizal associations of Rhododendron maximum in the southern Appalachian mountains were studied in relation to the supply and demand of phosphate at three altitudes. A variety of mycorrhizal associations are described together with the ability of the differing mycorrhizal types to produce phosphatase enzyme, which was inversely related to the availability of inorganic phosphate determined by a root bioassay, as Ectomycorrhizal associations were shown to have a higher phosphatase production potential than other mycorrhizas. The availability of inorganic phosphate at different altitudes is related to turnover of organic matter and fixation capacity of the mineral soil. It is speculated that the ability of R. maximum to associate with a range of mycorrhizal associates is likely to improve species' fitness and enhance its competitive ability.

Dissmeyer, G.E., and W.T. Swank. 1976. Municipal watershed management survey. Journal of American Water Works Association 68(2): 97-100.

Abstract
Based on survey data, this report provides a general summary of the nature and extent of land uses, management problems, and informational needs for municipal watersheds in the southeastern United States. Emphasis is placed on small and heavily forested watersheds and related forestry activities.

DiStefano, R.J., R.J. Neeves, L.A. Helfrich, and M.C. Lewis. 1991. Response of the crayfish Cambarus bartonii bartonii to acid exposure in southern Appalachian streams. Canadian Journal of Zoology 69: 1585-1591.

Abstract
Intermolt adult and juvenile Cambarus bartonii bartonii (Fabricius) from southern Appalachian Mountains streams tolerated considerable acidity when acutely exposed to greatly reduced pH levels in laboratory bioassays. Tolerance increased with increasing size or age of crayfish. Ninety- six-hour exposures yielded LC50 values of Ph 2.43, 2.56, and 2.85 for adults, advanced juveniles, and early juveniles, respectively. Lowering the water temperature increased the acid tolerance and survival time of intermolt adults during severe acidification (temperatures ranged from 20.2 to 13.3 C). Acid exposure of intermolt adults in soft water up to 96 h caused a linear decrease in hemolymph [Na}. Hemolymph [Ca] increased through 48 h and then returned to near pre-exposure levels. An initial increase in [k] was followed by a decrease to slightly below pre-exposure levels. Hemolymph [Mg] remained unchanged. No Ca was lost from carapaces. These observations indicate that occasional episodes of intermolt adult and juvenile C. b. bartonii. Nevertheless, gradually increasing acidity and loss of watershed buffering capacity could produce sublethal effects such as altered reproductive activity, or changes in early life history stages and more sensitive molt cycle stages, that could damage these populations.

Dixon, P.M., and J.H.K. Pechmann. 2005. A statistical test to show negligible trend. Ecology. 86(7): 1751-1756.

Abstract
The usual statistical tests of trend are inappropriate for demonstrating the absence of trend. This is because failure to reject the null hypothesis of no trend does not prove that null hypothesis. The appropriate statistical method is based on an equivalence test. The null hypothesis is that the trend is not zero, i.e., outside an a priori specified equivalence region defining trends that are considered to be negligible. This null hypothesis can be tested with two one-sided tests. A proposed equivalence region for trends in population size is a log-linear regression slope of (?0.0346, 0.0346). This corresponds to a half-life or doubling time of 20 years for population size. A less conservative region is (?0.0693, 0.0693), which corresponds to a halving or doubling time of 10 years. The approach is illustrated with data on four amphibian populations; one provides significant evidence of no trend.

Dodds, W.K., A.J. Lopez, W.B. Bowden, S. Gregory, N.B. Grimm, S.K. Hamilton, A.E. Hershey, E. Marti, W.H. McDowell, J.L. Meyer, D. Morrall, P.J. Mulholland, B.J. Peterson, J.L. Tank, H.M. Valett, J.R. Webster, and W. Wollheim. 2002. N uptake as a function of concentration in streams. Journal of the North American Benthological Society 21(2): 206-220.

Abstract
Detailed studies of stream N uptake were conducted in a prairie reach and gallery forest reach of Kings Creek on the Konza Prairie Biological Station. Nutrient uptake rates were measured with multiple short-term enrichments of NO3+ and NH4+ at constant addition rates in the spring and summer of 1998. NH4+ uptake was also measured with 15N+NH4++ tracer additions and short-term unlabeled NH4+ additions at 12 stream sites across North America. Concurrent addition of a conservative tracer was used to account for dilution in all experiments NH4+ uptake rate per unit area (U1) was positively correlated to nutrient concentration across all sites (r2= 0.41, log-log relationship). Relationships between concentration and U1were used to determine whether the uptake was nonlinear (i.e., kinetic uptake primarily limited by the biotic capacity of microorganisms to accumulate nutrients) or linear (e.g., limited by mass transport into stream biofilms). In all systems, U1 was lower at ambient concentrations than at elevated concentrations. Extrapolation from uptake measured from a series of increasing enrichments could be used to estimate ambient U1. Linear extrapolation of U1 assuming the relationship passes through the origin and rates measured at 1 elevated nutrient concentration underestimated ambient U1 by ~3-fold. Uptake rates were saturated under some but not all conditions of enrichment; in some cases there was no saturation up to 50 +mol/L. The absolute concentration at which U1 was saturated in Kings Creek varied among reaches and nutrients. Uptake rates of NH4+ at ambient concentrations in all streams were higher than would be expected, assuming U1 does not saturate with increasing concentrations. At ambient nutrient concentrations in unpolluted streams, U1 is probably limited to some degree by the kinetic uptake capacity of stream biota. Mass transfer velocity from the water column is generally greater than would be expected given typical diffusion rates, underscoring the importance of advective transport. the short-term spikes in nutrient concentrations that can occur in streams (e.g., in response to storm events), U1 may not saturate, even a high concentrations.

Dodds, W.K., Collins, S., Hamilton, S.K., Tank, J.L., Johnson, S.L., Webster, J., Whiles, M.R., Rantala, M., McDowell, W.H., Peterson, S., Riis, T., Crenshaw, C.L., Thomas, C., Cheever, B.M., Flecker, A., Griffiths, N., Crowl, T., Rosi-Marshall, E.J., El-Sabaawi, R. and Marti, E. 2014. You are not always what we think you eat: selective assimilation across multiple whole-stream isotopic tracer studies. Ecology. 95:2757-2767.

Abstract
Analyses of 21 15N stable isotope tracer experiments, designed to examine food web dynamics in streams around the world, indicated that the isotopic composition of food resources assimilated by primary consumers (mostly invertebrates) poorly reflected the presumed food sources. Modeling indicated that consumers assimilated only 33–50% of the N available in sampled food sources such as decomposing leaves, epilithon, and fine particulate detritus over feeding periods of weeks or more. Thus, common methods of sampling food sources consumed by animals in streams do not sufficiently reflect the pool of N they assimilate. Isotope tracer studies, combined with modeling and food separation techniques, can improve estimation of N pools in food sources that are assimilated by consumers. Food web studies that use putative food samples composed of actively cycling (more readily assimilable) and refractory (less assimilable) N fractions may draw erroneous conclusions about diets, N turnover, and trophic linkages of consumers. By extension, food web studies using stoichiometric or natural abundance approaches that rely on an accurate description of food-source composition could result in errors when an actively cycling pool that is only a fraction of the N pool in sampled food resources is not accounted for.

Dodds, W.K., E. Marti, J.L. Tank, J. Pontius, S.K. Hamilton, N.B. Grimm, W.B. Bowden, W.H. McDowell, B.J. Peterson, H.M. Valett, J.R. Webster, and S. Gregory. 2004. Carbon and nitrogen stoichiometry and nitrogen cycling rates in streams. Oecologia. 140: 458-467.

Abstract
Stoichiometric analyses can be used to investigate the linkages between N and C cycles and how these linkages influence biogeochemistry at many scales, from components of individual ecosystems up to the biosphere. N-specific NH4 + uptake rates were measured in eight streams using short-term 15N tracer additions, and C to N ratios (C:N) were determined from living and non-living organic matter collected from ten streams. These data were also compared to previously published data compiled from studies of lakes, ponds, wetlands, forests, and tundra. There was a significant negative relationship between C:N and N-specific uptake rate; C:N could account for 41% of the variance in N-specific uptake rate across all streams, and the relationship held in five of eight streams. Most of the variation in N-specific uptake rate was contributed by detrital and primary producer compartments with large values of C:N and small values for N-specific uptake rate. In streams, particulate materials are not as likely to move downstream as dissolved N, so if N is cycling in a particulate compartment, N retention is likely to be greater. Together, these data suggest that N retention may depend in part on C:N of living and non-living organic matter in streams. Factors that alter C:N of stream ecosystem compartments, such as removal of riparian vegetation or N fertilization, may influence the amount of retention attributed to these ecosystem compartments by causing shifts in stoichiometry. Our analysis suggests that C:N of ecosystem compartments can be used to link N-cycling models across streams.

Dodds, W.K., Webster, J., Crenshaw, C.L., Helton, A.M., O'Brien, J.M., Marti, E., Hershey, A.E., Tank, J.L., Burgin, A.J., Grimm, N.B., Hamilton, S.K., Sobata, D.J., Poole, G.C., Beaulieu, J.J., Johnson, L.T., Ashkenas, L.R., Hall, R.O., Johnson, S.L., Wollheim, W.M. and Bowden, W.B. 2014. The Lotic Intersite Nitrogen Experiments: an example of successful ecological research collaboration. Freshwater Science. 33(700-710).

Abstract
Collaboration is an essential skill for modern ecologists because it brings together diverse expertise, viewpoints, and study systems. The Lotic Intersite Nitrogen eXperiments (LINX I and II), a 17-y research endeavor involving scores of early- to late-career stream ecologists, is an example of the benefits, challenges, and approaches of successful collaborative research in ecology. The scientific success of LINX reflected tangible attributes including clear scientific goals (hypothesis-driven research), coordinated research methods, a team of cooperative scientists, excellent leadership, extensive communication, and a philosophy of respect for input from all collaborators. Intangible aspects of the collaboration included camaraderie and strong team chemistry. LINX further benefited from being part of a discipline in which collaboration is a tradition, clear data-sharing and authorship guidelines, an approach that melded field experiments and modeling, and a shared collaborative goal in the form of a universal commitment to see the project and resulting data products through to completion.

Dornelas M, Antão LH, Moyes F, et al. BioTIME: A database of biodiversity time series for the Anthropocene. Global Ecol Biogeogr. 2018; 00:1 - 26. https://doi.org/10.1111/geb.12729

Abstract
The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene. The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record. BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2). BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year. BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates.

Dougherty, P., D. Whitehead, and J. Vose. 1994. Environmental influences on the phenology of pine. Ecological Bulletins (Copenhagen) 43: 64-75.

Abstract
The phenology of six major timber producing species of pines is discussed. Phenophases that represent large sinks for carbohydrates are emphasized: height, bole diameter, branch and foliage development, and root growth. The role of environmental factors in altering initiation, cessation and growth activity of each phenophase is discussed.

Douglass, J E., and D.H. Van Lear. 1983. Prescribed burning and water quality at ephemeral streams in the Piedmont of South Carolina. Forest Science 29(1): 181-189.

Abstract
Soil and nutrient export were monitored before and after two prescribed burns 18 months apart on four pairs of treatment and control watersheds.

Douglass, J.E. 1960. Soil Moisture Distribution Between Trees in A Thinned Loblolly Pine Plantation. Journal of Forestry, 58(3).

Abstract
To obtain distribution information, soil moisture was observed in a 16-year-old loblolly pine plantation near Union, SC. Soil moisture samples were collected at the end of the first and second growing seasons following thinning when soil moisture had been largely depleted and when antecedent rainfall amounted to less than 0.7 inch for the preceding 4 weeks. Observations from this experiment illustrates a limitation of the use of random sampling methods for determining soil moisture. Random samples are valid for stands in which the amount of moisture does not differ significantly from place to place. However, during some seasons the amount of moisture under thinned stands may vary significantly at different distances from the tree and random sampling will give a biased moisture estimate. In such stands other sampling techniques, such as stratified sampling, can be employed to obtain unbiased moisture estimates and should be considered for use.

Douglass, J.E. 1967. Man, water, and the forest. Forest Farmer. 26(5): 6-20.

Abstract
This article describes what we are learning from forest hydrology research at Coweeta Laboratory in the heart of the Southern Appalachians where, for more than three decades, the inter-relationships between man's activities, the forest and water have been under study.

Douglass, J.E. 1974. Watershed values important in land use planning on southern forests. Journal of Forestry 72: 617-621.

Abstract
Forests cover 20 to 65 percent of the land in the major water resource regions of the South, and forest management practices regulate the volume and timing of streamflow from these lands. Although water quality is emerging as the major water problem, quantity and timing of streamflow are also imiportant watershed values which should be considered in land use planning. Protection or improvement of hydrologic performance of forest soils will continue to be an important consideration in planning.

Douglass, J.E. 1983. The potential for water yield augmentation from forest management in the Eastern United States. Water Resource Bulletin 19(3): 351-358.

Abstract
High rainfall and extensive forests in the East combine to produce excellent potential for managing forest for increased water yield. Models are presented that allow prediction of streamflow increase from hardwood and pine forests and are being routinely applied in land management planning on National Forests in the Southeast. However, because of the diverse land ownership patterns and the economic objectives of owners, realizing the potential will be difficult at best. The opportunity for realizing the full potential appears greatest where the land is publicly owned.

Dowd, J.F., and A G. Williams. 1989. Calibration and use of pressure transducers in soil hydrology. Hydrologic Processes 3: 43-49.

Abstract
None

Drooz, A.T., G.F. Fedde, and J.A. Copony. 1976. Egg parasite of the elm spanworm is not Telenomus alsophilae. Environmental Entomology 5(3): 492-494.

Abstract
These observations, field and laboratory tests, and re-examination of specimens submitted for specific determination indicate that T. alsophilae attacks eggs of the fall cankerworm and T. n. sp. parasitizes eggs of the elm spanworm.

Duan, K., Sun, G., McNulty, S. G., Caldwell, P. V., Cohen, E. C., Sun, S., Aldridge, H. D., Zhou, D., Zhang, L., and Zhang, Y.: Future shift of the relative roles of precipitation and temperature in controlling annual runoff in the conterminous United States, Hydrol. Earth Syst. Sci., 21, 5517-5529, https://doi.org/10.5194/hess-21-5517-2017, 2017

Abstract
This study examines the relative roles of climatic variables in altering annual runoff in the conterminous United States (CONUS) in the 21st century, using a monthly ecohydrological model (the Water Supply Stress Index model, WaSSI) driven with historical records and future scenarios constructed from 20 Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models. The results suggest that precipitation has been the primary control of runoff variation during the latest decades, but the role of temperature will outweigh that of precipitation in most regions if future climate change follows the projections of climate models instead of the historical tendencies. Besides these two key factors, increasing air humidity is projected to partially offset the additional evaporative demand caused by warming and consequently enhance runoff. Overall, the projections from 20 climate models suggest a high degree of consistency on the increasing trends in temperature, precipitation, and humidity, which will be the major climatic driving factors accounting for 43–50, 20–24, and 16–23 % of the runoff change, respectively. Spatially, while temperature rise is recognized as the largest contributor that suppresses runoff in most areas, precipitation is expected to be the dominant factor driving runoff to increase across the Pacific coast and the southwest. The combined effects of increasing humidity and precipitation may also surpass the detrimental effects of warming and result in a hydrologically wetter future in the east. However, severe runoff depletion is more likely to occur in the central CONUS as temperature effect prevails.

Dunford, E.G., and P.W. Fletcher. 1947. Effect of removal of stream-bank vegetation upon water yield. Transactions, American Geophysical Union 28: 105-110.

Abstract
This is a preliminary report on the results of removing stream-bank vegetation from Watershed 6 at the Coweeta Hydrologic Laboratory. Diurnal fluctuations in the streamflow were virtually eliminated. Cutting of riparian growth also resulted in an increase in yield of sufficient magnitude to be significant in water resource management.

Dyer, J.M. 2009. Assessing topographic patterns in moisture use and stress using a water balance approach. Landscape Ecol 24:391-403.

Abstract
Through its control on soil moisture patterns, topography's role in influencing forest composition is widely recognized. This study addresses shortcomings in traditional moisture indices by employing a water balance approach, incorporating topographic and edaphic variability to assess fine-scale moisture demand and moisture availability. Using GIS and readily available data, evapotranspiration and moisture stress are modeled at a fine spatial scale at two study areas in the US (Ohio and North Carolina). Model results are compared to field-based soil moisture measurements throughout the growing season. A strong topographic pattern of moisture utilization and demand is uncovered, with highest rates of evapotranspiration found on south-facing slopes, followed by ridges, valleys, and north-facing slopes. Southfacing slopes and ridges also experience highest moisture deficit. Overall higher rates of evapotranspiration are observed at the Ohio site, though deficit is slightly lower. Based on a comparison between modeled and measured soil moisture, utilization and recharge trends were captured well in terms of both magnitude and timing. Topographically controlled drainage patterns appear to have little influence on soil moisture patterns during the growing season. In addition to its ability to accurately capture patterns of soil moisture in both high-relief and moderate-relief environments, a water balance approach offers numerous advantages over traditional moisture indices. It assesses moisture availability and utilization in absolute terms, using readily available data and widely used GIS software. Results are directly comparable across sites, and although output is created at a fine-scale, the method is applicable for larger geographic areas. Since it incorporates topography, available water capacity, and climatic variables, the model is able to directly assess the potential response of vegetation to climate change.

Dymond, Salli F., Aust, W. Michael, Prisley, Stephen P., Eisenbies, Mark H., Vose, James M. (2014) Application of a Distributed Process-Based Hydrologic Model to Estimate the Effects of Forest Road Density on Stormflows in the Southern Appalachians, Forest Science, 60:6 1213-1223, doi:10.5849/forsci.13-60

Abstract
Managed forests have historically been linked to watershed protection and flood mitigation. Research indicates that forests can potentially minimize peak flows during storm events, yet the relationship between forests and flooding is complex. Forest roads, usually found in managed systems, can potentially magnify the effects of forest harvesting on water yields. The distributed hydrology-soil-vegetation model was successfully calibrated at an hourly time step for a 760-ha watershed in the Blue Ridge Mountains of North Carolina. The impacts of forest road density were modeled using uniform input parameters but changing road densities. Road densities tested were 0.5, 1.0, 3.0, 4.3, 6.0, and 12.0 km km2. Results indicate that increases in road density increased average stormflow volume by as much as 17.5% when road densities increased from 0.5 to 4.3 km km2 (P  0.05). Overall, model simulations suggest that minimizing road density necessitated by the land use and appropriate forest road best management practices can be used to minimize impacts on stormflow.

Earl, S.R., H.M. Valett, and J.R. Webster. 2006. Nitrogen saturation in stream ecosystems. Ecology. 87(12): 3140-3151.

Abstract
The concept of nitrogen (N) saturation has organized the assessment of N loading in terrestrial ecosystems. Here we extended the concept to lotic ecosystems by coupling Michaelis-Menten kinetics and nutrient spiraling. We propose a series of saturation response types, which may be used to characterize the proximity of streams to N saturation. We conducted a series of short-term N releases using a tracer (15 NO3-N) to measure uptake. Experiments were conducted in streams spanning a gradient of background N concentration. Uptake increased in four of six streams as NO3-N was incrementally elevated, indicating that these streams were not saturated. Uptake generally corresponded to Michaelis-Menton kinetics but deviated from the model in two streams where some other growth-critical factor may have been limiting. Proximity to saturation was correlated to background N concentration but was better predicted by the ratio of dissolved inorganic N (DIN) to soluble reactive phosphorus (SRP), suggesting phosphorus limitation in several high-N streams. Uptake velocity, a reflection of uptake efficiency, declined nonlinearly with increasing N amendment in all streams. At the time, uptake velocity was highest in the low vN streams. Our conceptual model of N transport, uptake, and uptake efficiency suggests that, while streams may be active sites of N uptake on the landscape, N saturation contributes to nonlinear changes in stream N dynamics that correspond to decreased uptake efficiency.

Edwards, L. 1979. The greening of a clearcut. Research Reporter 12(3): 6-8.

Abstract
An article discussing research on clearcut regrowth, focusing on nutrient conservation and distribution.

Effects of water quality on Appalachian Elktoe mussels in the Little Tennessee River. 2011. Geological Society of America (GSA) : Boulder, CO, United States.

Abstract
Alasmidonta raveneliana, the Appalachian Elktoe, is a freshwater mussel currently listed as critically endangered. An effort to restore their populations began in the mid-1990s, when only two populations were known to exist. After hurricanes Ivan and Francis in 2004 both populations were reduced to critical numbers and have steadily declined; by 2006 populations in the Little Tennessee River decreased by 80%. A hypothesized reason for this decline is a reduction in sediment and/or water quality associated with a combination of sedimentation from land use changes, agricultural runoff, mining, and industrial discharges. Alterations in sediment and water quality, and their potential impact on biota, have been tested by examination of dissolved and particulate trace metal concentrations and water quality parameters indicating the suitability of habitat available for sufficient aquatic health. Over the 2010 water year, hydro labs were deployed at three monitoring sites along the Little Tennessee River to evaluate the aquatic habitat. Collection and analysis of water samples for total, particulate, and dissolved concentrations of selected trace metals through ion chromatography and ICP-MS analysis was accomplished and variations in total suspended and dissolved sediment loads were determined along with flood events from sediment sampling and water grab samples collected across the hydrograph. Mussel shell material collected between 1990-2010 was analyzed to determine threats and bioaccumulation during the time of population decline. Findings show levels of trace metals in the sediment well above probable effect thresholds, backed by diluted uptake in the shells, but with limited copper or ammonia currently found through pore-water investigations at bio-available levels. Sediment analysis coupled with cores taken from an impoundment along the water-course show trends suggesting an increasing source of sulfitic rich minerals. The deposition of newly eroded sediment exposed across the basin by recent development is believed to be contributing to the exposure of this aquatic environment to fresh sulfitic oxides compared with the highly eroded sulfides normally present in a naturally eroding environment.

Eggert, S., Wallace, J. 2003. Reduced detrital resources limit Pycnopsyche gentilis (Trichoptera: Limnephilidae) production and growth. The North American Benthological Society, 22(3):388-400

Abstract
Leaf inputs in temperate forest streams may limit caddisfly production because leaf detritus serves both as a food and case-material resource. We estimated Pycnopsyche gentilis production in a stream experimentally decoupled from its riparian habitat and a reference stream for 8 y in the southern Appalachians. We also examined laboratory survivorship, growth, and case-building activ- ities of P gentilis in substrate containing various quantities of leaf material. Pycnopsyche gentilis pro- duction declined to 0 within 3 y of the start of litter exclusion. Abundance, biomass, and production of P gentilis were positively related to leaf litter standing crops. Maximum individual length of P gentilis was reduced when annual leaf standing crops fell below 25 to 50 g AFDM/m2. Observations of case construction for instars removed from their original leaf cases and kept in substrate with low leaf standing crop, showed that P gentilis was capable of rebuilding a case of available substrate and surviving for 3 to 4 wk before dying of starvation. Survivorship and growth were significantly greater for larvae reared at high and intermediate leaf standing crops, than at low leaf standing crop. Older instars had higher survivorship rates but lower growth rates than younger instars in the low litter substrates. Survivorship and growth rates were lower for some individuals forced to rebuild new cases, indicating an energetic cost associated with case-building activities. Our results demonstrate that the linkage between terrestrially derived organic matter and production of a caddisfly shredder was a consequence of food availability.

Eggert, S.L., and J.B. Wallace. 2001. Reduced detrital resources limit Pycnopsyche gentiles (Trichoptera: Limnephilidae) production and growth. North American Benthological Society: 22(3): 388-400.

Abstract
Leaf inputs in temperate forest streams may limit caddisfly production because leaf detritus serves both as a food and case-material resource. We estimated Pycnopsyche gentilis production in a stream experimentally decoupled from its riparian habitat and a reference stream for 8 y in the southern Appalachians. We also examined laboratory survivorship, growth, and case-building activities of P gentilis in substrate containing various quantities of leaf material. Pycnopsyche gentilis production declined to 0 within 3 y of the start of litter exclusion. Abundance, biomass, and production of R gentilis were positively related to leaf litter standing crops. Maximum individual length of P gentilis was reduced when annual leaf standing crops fell below 25 to 50 g AFDM/m(2). Observations of case construction for instars removed from their original leaf cases and kept in substrate with low leaf standing crop, showed that P gentilis was capable of rebuilding a case of available substrate and surviving for 3 to 4 wk before dying of starvation. Survivorship and growth were significantly greater for larvae reared at high and intermediate leaf standing crops, than at low leaf standing crop. Older instars had higher survivorship rates but lower growth rates than younger instars in the low litter substrates. Survivorship and growth rates were lower for some individuals forced to rebuild new cases, indicating an energetic cost associated with case-building activities. Our results demonstrate that the linkage between terrestrially derived organic matter and production of a caddisfly shredder was a consequence of food availability.

Eggert, S.L., and J.B. Wallace. 2003. Litter breakdown and invertebrate detritivores in a resource-depleted Appalachian stream. Archiv fur Hydrobiologie: 156(3): 315-338.

Abstract
We measured breakdown rates of leaves and small wood for the first three years in a stream in which detrital inputs were excluded for 7 years and in a reference stream located in the Appalachian Mountains of North Carolina, USA. Leaf and wood inputs were excluded using a gill-net canopy constructed over a 170-m section of stream. We hypothesized that red maple (Acer rubrum) and rhododendron (Rhododendron maxima) leaf breakdown rates would decline in the litter exclusion stream as shredder production decreased with each year of litter exclusion. In contrast, we expected faster wood breakdown rates in the litter exclusion stream as microbes and invertebrates shifted from leaves to wood as their primary organic matter resource. Consistent with our predictions, wood breakdown rates were significantly faster in the litter exclusion stream. We also found significantly slower processing rates of maple leaves in the litter exclusion stream compared to the reference stream during years 2 and 3. Slower breakdown rates for red maple leaves in the litter exclusion stream were associated with lower shredder production and estimated consumption rates in years 2 and 3. Shredder production and consumption rate estimates were also lower in the exclusion stream for rhododendron leaves, but leaf breakdown rates were not affected. We also found that shredder production in litterbags was 3-4 x greater than in benthic substrates in the litter exclusion stream. In contrast, shredder production in litterbags was similar to that in benthic substrates in the reference stream. These differences were probably due to the relatively low availability of organic matter in benthic substrates in the litter exclusion stream. Our data show shredders track high quality organic matter resources (leaves) and contribute to their loss rate, illustrating the interdependence of stream organisms and terrestrial organic matter input.

Eggert, S.L., Wallace, J.B. 2007. Wood biofilm as a food resource for stream detritivores. Limnology and Oceanography, 52(3): 1239-1245.

Abstract
Published assimilation efficiencies indicate that leaf detritus is a more nutritious food for stream invertebrates than wood. Some studies, however, suggest that wood and wood biofilms (epixylon) may be an important but overlooked resource. We measured assimilation efficiencies of three detritivores for leaves and epixylon and compared attributes of grazed versus ungrazed wood epixylon to assess its use by detritivores. Pycnopsyche gentilis (Trichoptera), Tipula abdominalis (Diptera), and Tallaperla spp. (Plecoptera) assimilated epixylon more efficiently (26–36%) than leaf detritus (9–17%). Epixylon assimilation efficiencies were T. abdominalis . Tallaperla spp. . P. gentilis. Grazed wood had significantly lower microbial respiration rates, bacteria densities and biomass, fungal and chlorophyll a biomass, and biofilm ash-free dry mass than ungrazed wood, indicating that detritivores fed on epixylon. Detritivores ingested leaves at a higher rate (0.09–0.47 g g21 d21) than epixylon (0.04–0.07 g g21 d21). Assimilation rates, which incorporate both assimilation efficiency and ingestion rate, however, indicated that Tallaperla spp. And T. abdominalis were better able to use epixylon than leaves, whereas P. gentilis was more efficient at using leaves. Wood biofilm is readily ingested and assimilated by some stream detritivores and may serve as an important but overlooked food resource in stream food webs.

Eggert, S.L., Wallace, J.B., Meyer, J.L. and Webster, J. 2012. Storage and export of organic matter in a headwater stream: responses to long-term detrital manipulations. Ecosphere. 3:75. (DOI: doi.org/10.1890/ES12-00061.1)

Abstract
Riparian habitats provide organic matter inputs that influence stream biota and ecosystem processes in forested watersheds. Over a 13-yr period, we examined the effects of litter exclusion, small- and large-wood removal, and the addition of leaf species of varying detrital quality on organic matter standing crop and export of organic and inorganic particles in a high-gradient headwater stream. Using eight pretreatment years of export data and two pretreatment years of particulate organic matter (POM) standing crop data, we report on 21 and 15 years of continuous export and POM standing crop results, respectively. Litter exclusion resulted in the elimination of leaf standing crop by the end of year three. Wood and fine benthic organic matter (FBOM) standing crops declined significantly during the exclusion and wood removal periods, but never completely disappeared. Following the introduction of artificial wood structures for retention, the addition of fast, slow, and mixed breakdown leaves in the treatment stream resulted in significantly increased mean annual leaf standing crops. After five years of leaf addition, FBOM standing crop and fine particulate organic matter (FPOM) export remained below pre-treatment levels. The reduction in leaf standing crop in the treatment stream resulted in significant increases in FPOM (2×), fine inorganic particulate (3×), and gravel export (10×). After small wood removal we observed significant increases in export of fine inorganic particulates (2×) and gravel (7×) from the treatment stream. A greater proportion of coarse and FBOM standing crop was exported from the treatment stream during the litter exclusion and small wood removal periods than from the reference stream. Following the addition of slow and mixed leaves this trend was reversed, demonstrating the importance of leaf standing crop in the retention of POM. Our long-term experiment demonstrates that the quantity and type of riparian inputs to forested headwater streams will affect POM standing crop and export of POM and sediments to downstream ecosystems, and that small wood is more critical to retaining sediments and POM in small streams than previously recognized.

Elliott, K J., and A.S. White. 1994. Effects of Light, Nitrogen, and Phosphorus on Red Pine Seedling Growth and Nutrient Use Efficiency. Forest Science 40(1): 47-58.

Abstract
Growth and nutrient use efficiency were determined for red pine (Pinus resinosa Ait.) seedlings grown at various levels of light, nitrogen, and phosphorus. Nutrient use efficiency was estimated for nitrogen (NUE) and phosphorus (PUE) and was calculated as biomass production divided by total nutrient content. Seedlings grown in high light had four to five times more biomass than those in the low light treatment. Nitrogen supply had a significant effect on total biomass as well as other biomass components. Phosphorus supply did not have a significant effect on any of the biomass components. NUE and PUE decreased with increased supply of N and P, respectively. The results of this study suggest that red pine seedlings can adjust their nutrient use efficiency, particularly for N, when light and nutrient availability are varied. NUE was highest with high light and low N-high P supply in nutrient solutions.

Elliott, K. J., J. M. Vose, and R. L. Hendrick. 2009. Long-term effects of high intensity prescribed fire on vegetation dynamics in the wine spring creek watershed, Western North Carolina, USA. Fire Ecology, 5(2): 66-85.

Abstract
We examined the long-term effects of a prescribed fire in a southern Appalachian watershed in Nantahala National Forest, western North Carolina, USA. Fire was prescribed in 1995 on this site by forest managers to restore a degraded pine (Pinus spp.)-hardwood community, specifically to stimulate forage production, promote pine and oak (Quercus spp.) regeneration, and increase plant diversity. Before and after the prescribed fire, permanent plots were sampled across a south-facing hillslope, which corresponded to three community types: mesic, near-stream cove (riparian); dry, mixed-oak (mid-slope); and xeric, pine-hardwood (ridge). In an earlier paper, we reported the first two years of post-burn vegetation response from this prescribed burn. In our current study, we compared the pre-burn (1994) forest condition with 10 years post-burn (2005) vegetation measurements to determine the effects of fire on the mortality and regeneration of overstory trees, understory shrubs, and herbaceous-layer species. Overstory mortality was high immediately after the burn at the ridge location and ten years after the fire. Mortality of pitch pine (Pinus rigida Miller) (91.8 %) and hickory (Carya spp.) (77.5 %) reduced overstory basal area from 26.97 m2 ha-1 pre-burn to 18.86 m2 ha-1 post-burn in 1995 and to 9.13 m2 ha-1 in 2005. At the mid-slope and riparian locations, no significant overstory mortality occurred over time. Understory density was significantly higher 10 years after the burn (2005) than pre-burn, and basal area had returned to pre-burn levels. Density of mountain laurel (Kalmia latifolia L.), black huckleberry (Gaylussacia baccata [Wang.] K. Koch), and blueberry (Vaccinium spp.) had increased due to prolific sprouting. The prescribed fire had varying effects on diversity across the hillslope gradient over time. On the ridge, overstory diversity declined following the fire (H’basal area = 1.14 in 1994, H’basal area = 0.75 in 1995, and H’basal area = 0.80 in 2005). Diversity significantly increased in the herbaceous layer and remained higher than pre-burn conditions through 2005 (H’cover = 1.02 in 1994, H’cover = 1.97 in 1995, and H’cover = 2.25 in 2005). For the mid-slope and riparian positions, no change in diversity was observed in the overstory, understory or herbaceous layer.

Elliott, K. J., J. M. Vose. 2010. The contribution of the Coweeta Hydrologic Laboratory to developing an understanding of long-term (1934-2008) changes in managed and unmanaged forests. Forest Ecology and Management.

Abstract
Long-term records from USDA Forest Service Experimental Forests and Ranges (EF&Rs) are exceptionally valuable scientific resources and common ground for research in natural resource management. Coweeta Hydrologic Laboratory, Southern Appalachian Mountains in western North Carolina, is one of 82 EF&Rs located throughout the United States and Puerto Rico. Since its establishment in 1934, the wealth and breadth of scientific knowledge gained from Coweeta Hydrologic Laboratory research has provided both public and private land managers information on forest land management and has added to the knowledge base of natural resource science. We described the early watershed research at Coweeta and used long-term measurements and inventories (from 1934 to 2008) to: (1) explore the influences of large-scale disturbances and vegetation responses on ecosystem processes and (2) assess the long-term and short-term impacts of an exotic, invasive species on a southern Appalachian deciduous forest. We focused on changes in vegetation patterns influenced by natural and managed disturbances and then described the linkages between long-term vegetation measurements and water yield and quality responses. For natural disturbances, we used a network of over 900 permanent vegetation plots established in reference watersheds and unmanaged areas; first measured in 1934 and a subset re-measured in 1969–1972, 1988–1993, and 2003–2008. For the managed disturbances, clearcuts and species conversion experiments, vegetation was measured in permanent plots within treated watersheds before and after treatment. By the time of the 1934 survey, the forest had only 10 years to recover from logging before chestnut blight (Cryphonectria parasitica) induced mortality of virtually all remaining Castanea dentata trees. With the loss of C. dentata as the dominant species, Acer rubrum and Quercus montana became the dominant species and Liriodendron tulipifera and Tsuga canadensis increased in coves and along riparian corridors. T. canadensis is currently threatened by another invasive species, hemlock woolly adelgid (HWA, Adelges tsugae), with 33% tree mortality between 2003 and 2008. Smaller-scale disturbances, such as drought and windthrow, have created canopy gaps and the disturbance agent, gap size, and species-specific demography (dispersal, survival, growth, and mortality) affected colonization and recruitment. In general, the composition of species recruiting into canopy gapswasa reflection of the vegetation already in place at the time of disturbance, because regeneration occurred primarily through saplings or sprouts. In managed forests, where gaps were much larger (9–59 ha), early successional species recruit and become established and the long-term vegetation patterns are different than in unmanaged forests. The vegetation data provide a description of changes in forest structure and composition through time and space, and they have been used to develop process-based models to scale-up to the catchment level. Long-term climatic, hydrologic, biogeochemical, and vegetation databases coupled with process-based ecohydrology and ecophysiology models are essential to understanding broader- and more complex environmental issues such as climate change, carbon cycling, atmospheric deposition, and water supply and quality.

Elliott, K. J., Miniat, C. F., Pederson, N. and Laseter, S. H. (2015), Forest tree growth response to hydroclimate variability in the southern Appalachians. Glob Change Biol, 21: 4627-4641. doi:10.1111/gcb.13045

Abstract
Climate change will affect tree species growth and distribution; however, under the same climatic conditions species may differ in their response according to site conditions. We evaluated the climate-driven patterns of growth for six dominant deciduous tree species in the southern Appalachians. We categorized species into two functional groups based on their stomatal regulation and xylem architecture: isohydric, diffuse porous and anisohydric, ring porous. We hypothesized that within the same climatic regime: (i) species-specific differences in growth will be conditional on topographically mediated soil moisture availability; (ii) in extreme drought years, functional groups will have markedly different growth responses; and (iii) multiple hydroclimate variables will have direct and indirect effects on growth for each functional group. We used standardized tree-ring chronologies to examine growth of diffuse-porous (Acer, Liriodendron, and Betula) and ring-porous (Quercus) species vs. on-site climatic data from 1935 to 2003. Quercus species growing on upslope sites had higher basal area increment (BAI) than Quercus species growing on mesic, cove sites; whereas, Acer and Liriodendron had lower BAI on upslope compared to cove sites. Diffuse-porous species were more sensitive to climate than ring porous, especially during extreme drought years. Across functional groups, radial growth was more sensitive to precipitation distribution, such as small storms and dry spell length (DSL), rather than the total amount of precipitation. Based on structural equation modeling, diffuse-porous species on upslope sites were the most sensitive to multiple hydroclimate variables (r2 = 0.46), while ring-porous species on upslope sites were the least sensitive (r2 = 0.32). Spring precipitation, vapor pressure deficit, and summer storms had direct effects on summer AET/P, and summer AET/P, growing season small storms and DSL partially explained growth. Decreasing numbers of small storms and extending the days between rainfall events will result in significant growth reduction, even in regions with relatively high total annual rainfall.

Elliott, K. J., Vose, J. M. 2010. Short-term effects of prescribed fire on mixed oak forests in the southern Appalachians: vegetation response. Journal of the Torrey Botanical Society, 137(1): 49-66.

Abstract
We examined vegetation responses to prescribed fire on three mixed-oak sites located in the Blue Ridge Physiographic province of the southern Appalachian Mountains: Alarka Laurel Branch (AL), Robin Branch (RB), and Roach Mill Branch (RM). Each of the study sites was within a sub-watershed that drained a first order stream. Our objectives were to: 1) evaluate overstory mortality following prescribed fire treatments; and 2) assess changes in composition, abundance, and diversity of overstory (stems = cm dbh), understory (stems , < cm dbh, = 0.5 m height), and herbaceous layer (woody stems < 0.5 m height and all herbaceous plants) vegetation in mixed-oak ecosystems. Each site included a burned and unburned area (control). Before the prescribed fire treatments were applied, we established permanent plots (10 x 20 m) in the prescribed burn areas (12 plots in AL, 12 plots in RB, and 10 plots in RM) and adjacent unburned areas (5 plots in AL, 6 plots in RB, and 4 plots in RM), for a total of 49 plots. Within the plots, we sampled vegetation before and after the prescribed burns. All of the prescribed fires were low to moderate intensity; i.e., they had moderate flame temperatures and low flame heights. After the prescribed fires, overstory mortality was low for all sites, and there were no significant differences between mortality in burned areas and that in unburned areas. Understory density was lower on the burned than the unburned plots the first (t = -5.26, P < 0.0001) and second (t = -3.85, P = 0.0020) growing seasons after burning. There was either an increase (AL, RB) or no change (RM) in herbaceous layer cover depending on the site and no significant change in species diversity after burning for any site. Thus, we found no negative effects of prescribed fire on herbaceous flora.

Elliott, K., and W. Swank. 1994.Impacts of drought on tree mortality and growth in a mixed hardwood forest. Journal of Vegetation Science 5: 229-236.

Abstract
The tree and shrub species on a 16-ha watershed in the Coweeta Basin were sampled in 1984 and again in 1991 to determine the effects of drought on tree species composition and basal area growth. Mortality and radial growth were determined for tree species within three community types that represent a moisture gradient from moist to dry: cove-hardwoods>mixed-oak>oak-pine. Tree mortality from 1984 to 1991 was 20% and 23% in the cove-hardwoods and mixed-oak communities, respectively, compared to only 12% in the oak-pine type. With the exception of Oxydendrum arboreum and Robinia pseudoacacia, the oaks had higher percentage mortality than any other genus. Mortality occurred mostly in the small-size class individuals (<10 cm in diameter) for all species, suggesting that thinning was still an important process contributing to mortality 29 yr after clearcutting. Although growth of Liriodendron tulipifera was much higher than growth of either Quercus prinus or Quercus coccinea, growth in Liriodendron was significantly reduced by the 1985-88 drought and no growth reduction was observed for these two dominant Quercus species during the same time.

Elliott, K..J., J.M. Vose, W.T. Swank, and P.V. Bolstad.1999. Long-term patterns in vegetation-site relationships in a southern Appalachian Forest. Journal of the Torrey Botanical Society. 126(4): 320-334.

Abstract
We used permanent plot inventories from 1969-1973 and 1988-1993 to describe forest species distribution patterns of the Coweeta Hydrologic Laboratory, a 2,185 ha basin in western North Carolina, USA. We used canonical correspondence analysis to explore the vegetation-site patterns for the 1970s and 1990s inventories combined. Site variables were determined by direct measurements or calculated by digital geographical information system mapping methods. Site variables were percent slope, elevation, terrain shape, precipitation, modified azimuth, soil organic matter content, soil depth, soil clay content, depth of A-horizon, potential solar radiation, and mean temperature during the growing season. For example, Acer rubrum, Quercus prinus, Oxydendrum arboreum, and Nyssa sylvatica were located in the center of the ordination space (i.e., their occurrence was not related to any of the site variables), which suggests that these species are habitat generalists.

Elliott, K.J. & Miniat, Chelcy. (2018). Herbaceous-layer diversity and tree seedling recruitment are enhanced following Rhododendron maximum shrub removal. Forest Ecology and Management. 430. 403-412. 10.1016/j.foreco.2018.08.016.

Abstract
Forest ecosystems dominated by Tsuga canadensis are undergoing fundamental changes in function and composition from infestations by hemlock woolly adelgid (Adelges tsugae). We proposed that the first step to restoring southern Appalachian riparian forests following T. canadensis mortality would be eliminating the evergreen shrub, Rhododendron maximum. We hypothesized that removing R. maximum would increase light transmittance, soil moisture and temperature; and subsequently, enhance herbaceous-layer diversity and promote tree seedling recruitment and survival. We tested these hypotheses at two locations, (CWT, Coweeta Hydrologic Laboratory; WOC, White Oak Creek) in the Nantahala Mountain Range of western North Carolina, both with heavy T. canadensis mortality and a dense R. maximum subcanopy. The treatments were designed to remove only soil Ohorizon (FF), remove only R. maximum (CR), remove R. maximum and soil O-horizon (CFFR), and untreated, reference (REF). We installed permanent plots across treatments and locations and measured light transmittance (Qi/Qo), soil water content (?), herbaceous-layer cover and diversity (Shannon’s index (H'cover) and species richness), and tree seedling recruitment. As expected, cutting the R. maximum subcanopy (CR and CFFR) immediately increased Qi/Qo in the spring months across locations, and it was sustained through the first growing season. ? was generally high across plots, averaging 26% during the growing season, and didn’t vary over time. By the second growing season (2017) after treatments, herbaceous-layer cover and diversity increased on CR and CFFR. Herbaceous-layer cover was significantly related to Qi/Qo (r2=0.22, p < 0.001) and ? (r2=0.13, p=0.009), while diversity was only related to Qi/Qo (H'cover, r2=0.14, p < 0.001; species richness, r2=0.21, p < 0.001). Tree seedling density was related to Qi/Qo (r2=0.10, p=0.001) and ? (r2=0.26, p < 0.001). Tree seedling density was low before treatment (1.4 ± 0.3 seedlings m-2) and increased by 10-fold in CR and CFFR two growing seasons after treatment. In CR, species with the highest density ranked Betula spp. > Acer rubrum > Quercus coccinea > Liriodendron tulipifera > Q. rubra. In CFFR, tree seedling recruitment ranked Betula spp. > A. rubrum > L. tulipifera. These vegetation responses have important implications for potential recovery of riparian forests following T. canadensis mortality.

Elliott, K.J. 1993. Vegetation diversity after logging in the Southern Appalachians. Conservation Biology. 7(2): 220-221.

Abstract
Elliot and Loftis review an article by Duffy and Meier, and express concerns with methods and interpretations presented in the article: 1) Decisions regarding the choice of both the size and number of sample plots are critical to any analysis of vegetation diversity, and there is no discussion regarding the rationale used by Duffy and Meier. 2) Reporting species richness on a per-plot basis can result in even further misinterpretation of the data if species are not randomly distributed. 3) Not sampling the entire community will bias the sample. 4) Floristic comparisons need to be made in other seasons as well. 5) The age gap of 84 years (secondary sites) to 200 years (primary sites) invalidates the statement in the conclusion that "the data presented here strongly suggest that recovery requires at least several centuries."

Elliott, K.J., and D. Hewitt. 1997. Forest species diversity in upper elevation hardwood forests in the southern Appalachian mountains. Castanes 62: 32-42.

Abstract
Overstory, shrub-layer, and herb-layer flora composition and abundance patterns in eleven forest sites were studied to evaluate species diversity and richness before implementing three types of harvest treatments. The sites were within the Wine Spring Creek Watershed and were classified as high elevation, dry, Quercus rubra-Rhododendron calendulaceum based on McNab and Browning's Landscape Ecosystem Classification system. Evaluation of species diversity was determined by Shannon-Weiner's index of diversity (H') and Pielou's species evenness index (J'). Overstory H' based on tree density ranged from 1.62 to 2.50 and H' based on tree basal area ranged from 0.94 to 2.22. The importance values for woody species, showed four species that occurred on all sites (Acer rubrum, Quercus rubra, Amelanchier arborea, and Castanea dentata) accounted for 32 to 84% of Overstory abundance. Shrub-layer H'Density ranged from 0.64 to 2.33 and H'BA ranged from 0.40 to 2.26. Rhododendron calendulaceum and Castanea dentata were the only species present on all sites and accounted for 28.5 to 92.3% of the shrub-layer abundance. Herb-layer H'Density ranged from 1.72 to 3.02 and J'Density was low, between 0.5 and 0.6 on most sites. Herb-layer diversity was determined by a few dominant species. Although species richness ranged from 51 to 73, seven genera of understory herbs [Prenanthes trifoliata, Thelypteris noveboracensis, Viola hastata, Medeola virginiana, Solidago (curtisii and arguta), and Carex spp., and Aster spp.] occurred on all sites and accounted for 50 to 91% of the total density and 27 to 75% of the total cover. Early successional species were well represented at all sites. Seedling survivorship, germination, and overstory contribution of seeds, caused varied site representation of species. This study provides base line data for observing variation in species richness and diversity that will result from experimental harvest methods.

Elliott, K.J., and J.D. Knoepp. 2005. The effects of three regeneration harvest methods on plant diversity and soil characteristics in the southern Appalachians. Forest Ecology and Management. 211: 296-317.

Abstract
We evaluated the effects of three regeneration harvest methods on plant diversity and soil resource availability in mixed hardwood ecosystems. The study area is in the Wine Spring Creek watershed on the Nantahala National Forest of the Southern Appalachian Mountains in western North Carolina. The regeneration treatments were: an irregular, two-aged shelterwood cut (2A), with 5.0 m2/ha residual basal area; a shelterwood cut (SW), with 9.0 m2/ha residual basal area; a group selection cut (GS), with 0.10v0.20 ha openings and 25% overstory removal on area basis at first entry; fourth, the control, consisted of two uncut sites (UC). Each harvest treatment was replicated three times across the landscape in similar plant community types. Within each treatment area, permanent plots were marked and inventoried for overstory, midstory, and herbaceous layer plants. In each permanent plot, we collected soil samples in winter (DecembervMarch) to reduce temporal variation due to vegetation phenological stage and rainfall events. We analyzed soil samples for extractable calcium (Ca), magnesium (Mg), potassium (K), cation exchange capacity (CEC), pH, bulk density, A-horizon depth, total carbon (C), and nitrogen (N). Species diversity of overstory, understory, and herbaceous layer species was evaluated using species richness (S), ShannonvWiener¼s index of diversity (H0), and Pielou¼s evenness index (E).We used direct gradient analysis (non-metric multidimensional scaling, NMS) to explore the changes in vegetationvsite relationships among herbaceous layer abundance, and soil characteristics and overstory basal area between pre-harvest (1994) and post-harvest (2000). Twelve minor overstory species were cut from the 2A treatments and nine species were cut from the SW treatments. Thus, it is not surprising that S and H0 were reduced in the overstory on the heavily cut sites. However, most of these species sprouted from cut stumps and were substantially more abundant in the midstory layer after harvest than before. For the midstory, we found higher S and H0 on the harvested treatments than the control; however, H0 did not differ significantly among the harvest treatments. We measured an increase in herbaceous layer H0 on the more heavily cut treatments (2A and SW) after harvest. We found an increase in average distance in the NMS ordination among sites in 2000 compared to 1994, which suggests greater herbaceous species diversity after harvest. However, we did not see a clear separation among harvest treatments in the NMS ordination.

Elliott, K.J., and J.M. Vose. 1993. Site preparation burning ot improve southern Appalachian pine-hardwood stands: photosynthesis, water relations, and growth of planted Pinus strobus L. during establishment. Journal of Forest Research 23: 2278-2285.

Abstract
We examined the physiological performance and growth of Pinustrobus L. seedlings the first growing season after planting on two clearcut and burned sites in the southern Appalachians. Growth of the seedlings was related to physiological measurements (net photosynthesis(P_N_), transpiration, leaf conductance, and xylem water potential), soil water, foliar N, seedling temperature, and light environment using regression analysis. Diameter growth increased with increasing foliar N concentration and decreased as competitorbiomass increased. Competition reduced growth by lowering foliar N, shading seedlings, and possibly reducing photosynthetic capacity. Increased temperature and lower available soil water may obscure these relationships on a harsh site.

Elliott, K.J., and J.M. Vose. 1994. Photosynthesis, water relations, and growth of planted Pinus strobus L. on burned sites in the southern Appalachians. Tree Physiology 14: 439-454.

Abstract
Physiology and growth of Pinus strobus L. seedlings were measured two years after planting on two clearcut and burned sites in the Southern Appalachians. Multiple regression analysis was used to relate seedling net photosynthesis to vapor pressure deficit, seedling crown temperature, photosynthetically active radiation (PAR), needle N, xylem water potential, and soil water. Analysis also related seedling size and growth to average net photosynthesis, leaf conductance, cumulative xylem water potential, soil water, needle N, seedling temperature, and PAR. Seedling net photosynthesis was significantly related to vapor pressure deficit, midday water potential, crown temperature, and PAR early in the growing season with vapor pressure deficit alone explaining 42 percent of the variation. As neighboring vegetation developed, light became more limiting and significantly reduced seedling net photosynthesis later in the growing season. Final seedling diameter was significantly related to competitor biomass, average photosynthetic rate, and needle N.

Elliott, K.J., and J.M. Vose. 1995. Evaluation of the competitive environment for white pine (Pinus strobus L.) seedlings planted on prescribed burn sites in the southern Appalachians. Forest Science 41(3): 513-530.

Abstract
We evaluated the competitive environment around planted white pine (Pinus strobus L.) seedlings and monitored the response of seedling growth to competition from naturally regenerating herbaceous and woody species for 2 yr after prescribed burning. We evaluated the ability of distance-independent and distance-dependent competition indices to predict resource availability, determined if white pine seedlings responded to resource reduction by competitors, and identified species-specific contributions to the competitive environment through canonical correspondence analysis (CCA). Distance-independent measures of competition were not as well correlated with pine seedling growth as were distance-dependent measures. In 1991, competition was less important in 1991 than in 1992, and ordinating the species with CCA failed to improve the predictability of the competitive environment. By 1992, competition became more important, and individual species had differing effects on pine growth; we found that light was the most important resource limiting diameter growth and that the tall tree species were responsible for reduced light availability to pine seedlings.

Elliott, K.J., and J.M. Vose. 2005. Effects of understory prescribed burning on shortleaf pine (Pinus echinata Mill.)/mixed-hardwood forests. Journal of the Torrey Botanical Society. 132(2): 236-251.

Abstract
We examined the effects of a single dormant season fire on overstory and understory species diversity and composition and tree seedling regeneration patterns the first and second years following a prescribed burn in the Conasauga River Watershed of southeastern Tennessee and northern Georgia. We asked: Can a single dormant season fire initiate a trajectory of overstory and understory species change consistent with restoring Pinus echinata/mixed-oak/bluestem (Andropogon gyrans and Schizachyrium scoparium)-grass community types? Six sub-watersheds (similar in vegetation, soil type, stream size, and disturbance history) were located within the Conasauga River Watershed; four of the sites were burned in March 2001, and two sites were designated as controls. Within each site, vegetation was measured in layers: the overstory layer (trees ?5.0-cm DBH), the midstory layer (woody stems < 5.0-cm DBH and ? 0.5 m height), and the ground flora layer (woody stems < 0.5-m height and all herbaceous species). All plots were sampled before the prescribed burn (Sept. 2000) and after the burn in July of 2001 and 2002. Consistent with the goals of the land managers, all the prescribed fires resulted in low-to-moderate intensity and low severity fires. However, we found no significant change in overstory, midstory, or ground flora species diversity after burning. We found no regeneration of P. echinata seedlings after the prescribed fire. Although fire reduced basal area of woody species in the midstory, prolific sprouting from hardwoods resulted in higher density of fire-sensitive hardwoods such as Acer rubrum, Oxydendrum arboretum, and Nyssa sylvatica. Density of Pinus strobus, an undesirable species, was reduced by 20% and its basal area was reduced by 50% after the burn. Overstory mortality occurred in small size class hardwoods as a result of the fi P. echinata and P. virginiana Miller due to infestation with pine bark beetles. The prescribed fires were not of sufficient intensity to: reduce overstory basal area, prepare a seedbed for successful pine germination, affect diversity of any of the vegetation layers, or promote A. gyrans and S. scoparium recruitment. Thus, additional fire treatments or a combination of fire and thinning treatments will be necessary to restore these ecosystems to P. echinata/mixed-oak/bluestem grass community types.

Elliott, K.J., and J.M. Vose. 2005. Initial effects of prescribed fire on quality of soil solution and streamwater in the southern Appalachian mountains. Southern Journal of Applied Forestry. 29(1): 5-15.

Abstract
Prescribed burning is being used in the Conasauga River Watershed in southeastern Tennessee and northern Georgia by National Forest managers to restore degraded pine/oak communities. The purpose of these burns is to restore shortleaf pine (Pinus echinata Miller) (mixed-oak forests with more diverse understories, which include native bluestem grasses (Andropogon gyrans Ashe and Schizachyrium scoparium (Michx.) Nash). Although burning might be an effective tool for restoring these stands to a shortleaf pine/mixed-oak/bluestem grass community type, it is not know whether these restoration burns will have a negative impact on water quality. Six sub watersheds (similar in vegetation, soil type, stream size and location, and disturbance history) were located within the Conasauga River Watershed. Four of the sites were burned in Mar. 2001, and two sites were designated as controls. To evaluate initial effects of prescribed burning on water quality, we measured soil solution and streamwater nutrient concentrations and streamwater sediment concentrations (TSS; total suspended solids) weekly over a 10-month period. Consistent with goals of the land managers, all the prescribed fires resulted in low- to moderate-intensity and low-severity fires. Soil solution and streamwater NO3-N and NH4+-N did not increase after burning on any of the sites. We found no differences in TSS between burn and control streams in any of the sample periods. In addition, we found no detectable differences between control and burned sites for concentrations of PO43-, SO42-, Ca2+, Mg2+, K+, or pH in soil solution or streamwater. Thus, these prescribed restoration fires did not have a significant effect on soil solution and stream chemistry or stream sediment (TSS) concentrations. Our results suggest that low-intensity, low severity fires, such as those in this study, could be used as a tool to restore vegetation structure and composition in these mixed pine-hardwood ecosystems without negatively impacting water quality.

Elliott, K.J., and W.T. Swank. 1994. Changes in tree species diversity after successive clearcuts in the Southern Appalachians. Vegetation 115: 11-18.

Abstract
A 16 ha watershed in the Coweeta Basin was clearcut in 1939 and 1962. Vegetation was inventoried in 1934 and at about 7-year intervals to 1991. After the first clearcut, tree diversity remained high until after the second cut. Diversity based on density and basal area decreased significantly 14 years after the second clearcut and remained low through 1991. Diversity was highest in the early establishment stage of stand development, then declined at the intermediate stage with canopy closure. Evenness based on basal area declined more than evenness based on density because basal area of Liriodendron tulipifera increased substantially from 1977 to 1991. Trends in diversity were due to changes in evenness rather than changes in species richness.

Elliott, K.J., and W.T. Swank. 2008. Long-term changes in forest composition and diversity following early logging (1919-1923) and the decline of American chestnut (Castanea dentate). Plant Ecology. 197: 155-172.

Abstract
Chestnut blight fungus (Endothia parasitica [Murr.] P.J. And. & H.W. And.)) is a classic example of an invasive species, which severely damaged populations of its host, Castanea dentata, and had widespread and long-term impacts on eastern North American forests. Concurrently, forests were further disturbed by lumbering, which was common across the region from the mid 1800s to the early 1900s. In 1926, local infestations of chestnut blight were reported in the Coweeta Basin, Southern Appalachian Mountains of North Carolina. We used permanent plot inventories of the Basin (first sampled in 1934 and twice afterward in 1969–72 and 1988–93) to describe the distribution of species along a complex environmental gradient. Specifically, we asked: How does vegetation change over approximately 60 years following logging and the demise of C. dentata? Does the association between vegetation and environment determine the pattern of species distributions through time? Which species replaced C. dentate across this complex environmental gradient? We used nonmetric multidimensional scaling ordination and multiresponse permutation procedure for the analyses of the inventory periods. In 1934, C. dentata was the most important species in the Coweeta Basin. It was present in 98% of the plots and contributed 22% of the total density and 36% of the total basal area. Diversity increased significantly over time and was attributed to an increase in evenness of species distribution. The canopy dominant, C. dentata, was replaced by more than one species across the environmental gradient. Importance values of Quercus prinus, Acer rubrum, Cornus florida, Tsuga canadensis, and Oxydendrum arboreum increased by 2–5% across the basin following the decline of C. dentata. Tsuga canadensis increased in abundance and distribution, especially near streams across elevations. Liriodendron tulipifera replaced C. dentate in moist coves, which have low terrain shape and high organic matter content. In contrast, Q. prinus and A. rubrum were ubiquitous, much like C. dentate before the chestnut blight becoming dominant or co-dominant species across all environmental conditions.

Elliott, K.J., J.M. Vose, and B.D. Clinton. 2002. Growth of Eastern White Pine (Pinus strobus L.) Related to Forest Floor Consumption by Prescribed Fire in the Southern Appalachians. Southern Journal of Applied Forestry. 26(1): 18-25.

Abstract
Chainsaw felling, burning, and planting of eastern white pine (Pinus strobus L.) have been prescribed on degraded pine/hardwoods stands in the Southern Appalachians to improve overstory composition and productivity. He desired future condition of the overstory is a productive pine/hardwood mixture, with white pine, which is resistant to southern pine beetle (Dendroctonus frontalis), as the dominant pine. We evaluated the growth of white pine planted after fell-and burn treatments through eight growing seasons after planting on three sites that differed in their fire characteristics and carbon and nitrogen losses. The three sites (JE, JW, and DD) differed in heat penetration and forest floor consumption. Although very little consumption of the Oe+Oa humus layer occurred during burning, consumption of the Oi litter layer was 94%, 94%, and 63% at JE, JW, and DD, respectively. Corresponding to the forest floor layer consumption (Oi and Oe+Oa combined), 46% of forest floor N was lost at JE, 45% of forest Floor N was lost at JW, and less than 0.1% of the forest floor N was lost at DD. Biomass and density of woody competitor species were not significantly related to white pine size or growth. By the eighth growing season, no differences in white pine size or growth were detected between JE and JW, but DD had significantly smaller white pine trees. The size difference between DD and the other two sites was attributed to the replanting of seedlings at DD in 1992. However, relative growth rate (RGR) was significantly higher on DD in 1998 than the other two sites. Eight growing seasons after planting, white pine growth was negatively related to percent Oi layer consumed on the JE and JW sites. We also found significant relationships between white pine RGR and percent Oi consumed using data from all three sites. Although fire severity had a long-term effect on pine growth, fire severity was considered low overall on these sites because there were limited losses from the forest floor Oe+Oa layer. However, white pine increment and RGR were significantly related to percent forest floor Oi mass and N loss. This loss of site N capital could have a significant negative effect on growth of planted white pine over the long term

Elliott, K.J., J.M. Vose, and D. Rankin (2014). Herbaceous-layer species composition and richness of mesophytic cove forests in the southern Appalachians: Synthesis and Knowledge Gaps. Journal of the Torrey Botanical Society. 141 (1), 39-71

Abstract
We synthesized the current information on mesophytic cove forests in the southern Appalachians, assessed the range of variation in herb species composition and diversity in stands with different disturbance histories and environmental conditions, identified key knowledge gaps, and suggested approaches to fill these knowledge gaps. The purpose of this synthesis was to provide information to forest managers to help make decisions about conservation assessments and strategies for rich cove forests in the southern Appalachians. An important finding is that no single study or data set can provide conclusive evidence or clear management strategies. However, an overriding conclusion is that the magnitude of impact and the management actions necessary to restore herbaceous communities are directly proportional to the severity of disturbance, current condition (e.g., presence of Rhododendron), site heterogeneity, and historical land use (e.g., agricultural activity). These factors plus a host of other stressors (e.g., climate variability, air pollution, invasives) are likely to have a strong influence on the highly variable patterns observed when comparing herbaceous diversity of ‘old-growth’ or uncut forests to human disturbed forests (e.g., cutting, air pollution, conversion, invasive plants or insects). Results from this review reinforce our premise that factors controlling herbaceous species presence and abundance are highly complex, thus broad generalizations about the impacts of a single factor such as logging should be interpreted with caution. Of the stressors known to affect forest trees (e.g., pests and pathogens, acidic deposition, air pollution, drought, and wind), little to no information exists on how these same stressors will affect herbaceous plants. A limited number of studies have examined the demography or physiology of forest herbs, particularly across all life stages. While the demography of a few genera have been studied (e.g., Hexastylis, Asarum, Trillium, Arisaema, Goodyera, Hepatica), little to no information exists for the majority of woodland herbs. Species identity is important when considering management of rich cove forests. Diversity may increase following canopy disturbances that favor recruitment of early-seral herbaceous species; therefore, simple indices of diversity (H', S, and E) are not the best measure of recovery in mesophytic rich coves, particularly where shade-adapted ‘rich-cove indicator’ species have been replaced by these species. Species-specific life histories and the influence of prevailing site conditions are important lines of research for understanding recovery and sustainability of mesophytic rich cove forests.

Elliott, K.J., J.M. Vose, J.D. Knoepp, B.D. Clinton. 2012. Restoring shortleaf pine (Pinus echinata)-hardwood ecosystems severely impacted by the southern pine beetle (Dendroctonus frontalis Zimmerman). Forest Ecology and Management 274:181-200.

Abstract
In the Southern Appalachian Mountains of eastern USA, pine-hardwoodecosystems have been severelyimpacted by the interactions of past land use, fire exclusion, drought, and southernpinebeetle (SPB, Dendroctonusfrontalis). We examined the effects of restoration treatments: burn only (BURN); cut + burn on dry sites (DC + B); cut + burn on sub-mesic sites (MC + B); and reference sites (REF; no cutting or burning) on shortleafpine-hardwood forests. We also evaluated the effectiveness of seeding native bluestem grasses. Structural (down wood, live and dead standing trees, shrubs, herbaceous layer) and functional (forest floor mass, C, and N; soil C, N, P, and cations; and soil solution N and P) attributes were measured before and the first and second growing seasons after treatment. We used path analysis to test our conceptual model that restoration treatments will have direct and indirect effects on these ecosystems. Total aboveground mass loss ranged from 24.33 Mg ha-1 on the BURN to 74.44 Mg ha-1 on the DC + B treatment; whereas, REF gained 13.68 Mg ha-1 between pre-burn and post-burn. Only DC + B sites had increased soil NO3–N, NH4–N Ca, Mg, and PO4–P and soil solution NO3–N, NH4–N, O–PO4 for several months. We found a significant increase in the density of oak species (Quercus alba, Q. coccinea, Q. montana, Q. rubra, and Q. velutina) on all burn treatments. However, oaks accounted for a smaller proportion of the total stem density than red maple, other tree species, and shrubs. The high densities of woody species other than oaks, coupled with the fast growth rates of some of these species, suggests that oaks will continue to be at a competitive disadvantage in these pine-hardwood communities through time, without further intervention. Pine regeneration was not improved on any of our burned sites with little to no recruitment of pines into the understory after two years and the pine saplings that were present before the burns were killed by fire on all sites. We found an increase in herbaceous layer cover and richness on all fire treatments. DC + B had higher bluestem grass cover than the other treatments, and it was the only treatment with increased bluestem grass cover between the first (2.96%, SE = 0.29) and second (6.88%, SE = 0.70) growing seasons. Our path model showed that fire severity explained a large proportion of the variation in overstory response; and fire severity and overstory response partially explained soil NO3–N. These variables, directly and indirectly, explained 64% of the variation in soil solution NO3–N at 30 cm soil depth (within the rooting zone for most plants). We found a good-fit path model for herbaceous layer response in the second growing season, where fire severity had direct effects on overstory and herbaceous layer responses and indirect effects on herbaceous layer response mediated through overstory response. Our path model explained 46% and 42% of the variation in herbaceous layer cover and species richness, respectively.

Elliott, K.J., J.M. Vose, J.D. Knoepp,D.W. Johnson, W.t. Swank,and W. Jackson. 2008. Simulated effects of sulfur deposition on nutrient cycling in class I wilderness areas. Journal of Environmental Quality. 37: 1419-1431.

Abstract
We predicted the effects of sulfate (SO4) deposition on wilderness areas designated as Class I air quality areas in western North Carolina using a nutrient cycling model (NuCM). We used three S deposition simulations: current, 50% decrease, and 100% increase. We measured vegetation, forest floor, and root biomass and collected soil, soil solution, and stream water samples for chemical analyses. We used the closest climate stations and atmospheric deposition stations to parameterize NuCM. The areas were: Joyce Kilmer (JK), Shining Rock (SR), and Linville Gorge (LG)

Elliott, K.J., J.M. Vose. 2012. Age and distribution of an evergreen clonal shrub in the Coweeta Basin: Rhododendron maximum L. Journal of Torrey Botanical Society 139(2):149-166.

Abstract
Rhododendron maximum L. is an evergreen, clonal shrub that forms a dominant sub-canopy layer and is a key species in southern Appalachian forests. We investigated the age and distribution of R. maximum across the Coweeta Basin, a 1626 ha watershed in western North Carolina. We selected 16 perennial, second-order streams and used a Global Positioning System to establish site boundaries and map the coverage of R. maximum across the hillslopes from stream to ridge. In each site, three transects from stream edge to the ridge were used to measure diameters of overstory trees (= 2.5 cm dbh), tree saplings (< 2.5 cm dbh) and shrubs including R. maximum stems. Along each transect, we cut cross-sections of R. maximum ramets and extracted increment cores from nearest neighbor trees to determine ages. The 16 sites ranged in size from 0.3 to 1.9 ha depending on the distance from stream to ridge. Rhododendron maximum cover ranged from 25 to 100% and ages ranged from 6 to 120 years. Rhododendron maximum establishment year showed a skewed unimodal distribution with the peak establishment occurring between 1928 and 1940. Although the R. maximum age and distance-from-stream relationship was statistically significant, the relationship was not meaningful as distance-from-stream only explained 2.6% of the variation in R. maximum age (r2 = 0.026, P = 0.0003, n = 487). Distance from stream only explained 4.2% of the variation in overstory tree age (r2 = 0.042, P = 0.0015, n=237). It appears that R. maximum has not expanded upslope over the last 100 years; rather the ranges in sizes and ages suggest that ramets are recruiting under established R. maximum canopies particularly in the wetter, near stream locations. - See more at: http://www.srs.fs.usda.gov/pubs/41289#sthash.TXXDCA5s.dpuf

Elliott, K.J., L.R. Boring, and W.T. Swank. 1998. Changes in Vegetation Structure and Diversity After Grass-to Forest Succession in a Southern Appalachian Watershed. American Midland Naturalist. 140: 219-232.

Abstract
To document how species richness and diversity (H') recover from severe large-scale disturbance, we report temporal patterns of species composition and diversity following grass-to-forest succession from a long-term experiment in the Coweeta Basin, western North Carolina. The original experiment+clear-cutting, 5 yr of grass cover followed by a herbicide treatment, and abandonment in a Southern Appalachian mixed deciduous forest+represents the most severe human disturbance in the Coweeta Basin. For several years after cessation of management, Robinia pseudoacada quickly sprouted from roots and exceeded the growth rates of other species. Liriodendran tulipifera increased in density and basal area because of its prolific seedling establishment and rapid growth rate. Regeneration of large seeded species was mixed+sparse for Quercus rubra and Q. coccinea and nonexistent for Q. prinus and Q vehitina. In the overstory, density-based H' increased from 1958, before grass conversion, to 15 yr and 28 yr following disturbance. In contrast, basal area-based H' had significantly declined at 15 yr, then increased at 28 yr. The initial decline in basal area-based H' was attributed to a decline in evennness of species distribution ([') rather than to a change in species richness. The severe disturbance increased the abundance of early suc-cessional woody species and of herbaceous genera that tolerate open habitats, such as Eri-cktites, Phytolacca, and Erigeron. Shade-tolerant understory ferns and herbs such as Polysti-chum acrostichoides, Dennstaedtia punctilobula, Galium lalifolium and Viola cu-cullata gradually became more abundant. The 28-yr-old forest of WS6 had much lower species richness than the adjacent reference watersheds, but more than threefold higher density.

Elliott, K.J., L.R. Boring, and W.T. Swank. 2002. Aboveground biomass and nutrient accumulation 20 years after clear-cutting a southern Appalachian watershed. Canadian Journal of Forest Research. 32: 667-683.

Abstract
In 1975, we initiated a long-term interdisciplinary study of forest watershed ecosystem response to clear-cutting and cable logging in watershed 7 at the Coweeta Hydrologic Laboratory in the southern Appalachian Mountains of North Carolina. This paper describes f+20 years of change in species composition, aboveground biomass, leaf area index (LAI), and nutrient pools in the 59-ha mixed hardwood forest of watershed 7 following commercial clear-cutting in winter 1977. We measured woody species in 24 permanently marked plots before cutting in 1974 and during subsequent years (1977-1997). By 1997 (f+20 years after cutting), aboveground biomass was 81.7, 96.9 and 85.4 Mg∙ha-1 in the cove hardwood; mesic, mixed-oak; and dry, mixed-oak communities, respectively. Leaf biomass and LAI accumulated relatively faster than total aboveground biomass in ll three communities. By 1984, only 7-8 years after cutting, leaf biomass and LAI were nearly equal to the amount estimated for the precut forest. In 1997, nitrogen accumulation was 36, 44, and 61% and phosphorus accumulation was 48, 66, and 59% in the cove-hardwoods; mesic, mixed-oak; and dry, mixed-oak communities of the corresponding precut communities, respectively. Potassium, calcium, and magnesium accumulations were less than either nitrogen or phosphorus accumulation.

Elliott, K.J., L.R. Boring, W.T. Swank, and B.R. Haines. 1997. Successional changes in plant species diversity and composition after clearcutting a southern Appalachian watershed. Forest Ecology and Management 92: 67-85.

Abstract
Watershed 7, a southwest-facing watershed in the Coweeta Basin, western North Carolina, USA, was clearcut in 1977. Twenty-four permanent plots were inventoried in 1974 before cutting and in 1977, 1979, 1984, and 1993 after clearcutting. This study evaluates changes in species diversity during early succession after clearcutting and differences in overstory tree and ground flora response to disturbance by clearcutting and their interaction with previous disturbances and subsequent stand development. To quantify species diversity, we computed Shannon-Weaver's index of diversity (#') and Pielou's evenness index (/'). Woody species diversity remained relatively stable; however, woody species richness increased in the cove-hardwoods and hardwood-pines, but remained relatively constant in the mixed-oak hardwoods. Although revegetation was rapid, forest composition has changed through succession. Opportunistic species, such as Liriodendron tulipifera, Robinia pseudoacacia, and Acer rubrum, increased in abundance, whereas Quercus velutina, Carya spp., and Q. rubra decreased. Ground flora diversity declined in the cove-hardwoods and mixed-oak hardwoods communities, but the decrease in the hardwood-pines was not significant. The abundance (g biomass m~2) of ground flora was much lower in 1993 than in 1984; 79% less in the cove-hardwoods, 90% less in the mixed-oak hardwoods, and 79% less in the hardwood-pines. Watershed 7 is apparently in a transition state between early and late Successional species abundance. Early successional, shade-intolerant species, such as Erechtites, Solidago, Eupatorium, Panicum, and Aster, have declined, whereas late successional, shade-tolerant species, such as Viola, Galium, Sanguinaria, Uvularia, and Veratrum are not yet well established.

Elliott, K.J., L.R. Boring, W.T. Swank, and B.R. Haines. 1998. Changes in vegetation structure and diversity after grass-to-forest succession in a southern Appalachian watershed. American Midland Naturalist 140: 219-232.

Abstract
To document how species richness and diversity (H') recover from severe large-scale disturbance, we report temporal patterns of species composition and diversity following grass-to-forest succession from a long-term experiment in the Coweeta Basin, western North Carolina. The original experiment-clear-cutting, 5 yr of grass cover followed by a herbicide treatment, and abandonment in a Southern Appalachian mixed deciduous forest-represents the most severe human disturbance in the Coweeta Basin. For several years after cessation of management, Robinia pseudoacacia quickly sprouted from roots and exceeded the growth rates of other species. Liriodendron tulipifera increased in density and basal area because of its prolific seedling establishment and rapid growth rate. Regeneration of large seeded species was mixed-sparse for Quercus rubra and Q. coccinea and nonexistent for Q. prinus and Q. velutina. In the overstory, density-based H' increased from 1958, before grass conversion, to 15 yr and 28 yr following disturbance. In contrast, basal area-based H' had significantly declined at 15 yr, then increased at 28 yr. The initial decline in basal area-based H' was attributed to a decline in evennness of species distribution (J') rather than to a change in species richness. The severe disturbance increased the abundance of early suc-cessional woody species and of herbaceous genera that tolerate open habitats, such as Erichtites, Phytolacca, and Erigeron. Shade-tolerant understory ferns and herbs such as Polystichum acrostichoides, Dennstaedtia punctilobula, Galium latifolium and Viola cucullata gradually became more abundant. The 28-yr-old forest of WS6 had much lower species richness than the adjacent reference watersheds, but more than threefold higher density.

Elliott, K.J., R.L. Hendrick, A.E. Major, J.M. Vose, and W.T. Swank. 1999. Vegetation dynamics after a prescribed fire in the southern Appalachians. Forest Ecology and Management. 114: 199-213.

Abstract
In April 1995, the USDA Forest Service conducted a prescribed burn along with a south-facing slope of southern Appalachian watershed, Nantahala National Forest, western NC. Fire had been excluded for over 70 years and the purpose of the burn was to create a mosaic of fire intensities to restore a degraded pine/hardwood community and to stimulate forage production and promote oak regeneration along a hillslope gradient. Permanent plots were sampled at three locations along a gradient from 1500 to 1700 m. Plot locations corresponded to three community types: mesic, near-riparian cove (low slope); dry, mixed-oak (mid slope); and xeric, pine/hardwood (ridge). Before burning (1994-1995) and post-burn (summer, 1995 and summer, 1996) vegetation measurements were used to determine the effects of fire on the mortality and regeneration of overstory trees, understory shrubs, and herbaceous species. After the burn, mortality was highest (31%) at the ridge location, substantially reducing overstory (from 26.84 pre-burn to 19.05 m2ha-1 post-burn) and understory shrub (from 6.52 pre-burn to 0.37 m2ha-1 post-burn) basal area. At the mid-slope position, mortality was only 3%, and no mortality occurred at the low slope. Not surprisingly, percent mortality corresponded to the level of fire intensity. Basal area of Kalmia latifolia, Gaylussacia baccata, and Vaccinium spp. were substantially reduced after the fire, but density increased due to prolific sprouting. The prescribed fire had varying effects on species richness and diversity across the hillslope gradient. On the ridge, diversity was significantly increased in the understory and herb-layer, but decreased in the overstory. On the mid slope, no change was observed in the overstory, but diversity significantly decreased in the understory. On the low slope, no change was observed in the overstory or understory.

Elliott, K.J., S.L. Hitchcock, and L. Krueger. 2002. Vegetation response to large scale disturbance in a southern Appalachian forest: Hurricane Opal and salvage logging. Journal of the Torrey Botanical Society. 129(1): 48-59.

Abstract
Disturbance such as catastrophic windthrow can play a major role in the structure and composition of southern Appalachian forests. We report effects of Hurricane Opal followed by salvage logging on vegetation dynamics (regeneration, composition, and diversity) the first three years after disturbance at the Coweeta Hydrologic Laboratory in western North Carolina. The objective of this study was to compare species composition and diversity of understory and groundlayer species was much higher in the H+S forest than in the undisturbed forest, and abundance increased over time. Percent cover, density, and species richness were significantly higher in the H+S forest than in the undisturbed forest. In addition, percent cover increased by approximately 85% between 1997 and 1999 in the H + S plots. Shannon+s index of diversity (H+) based on percent cover was significantly higher in the H+S forest than the undisturbed forest by the third year after disturbance. However, there was no significant difference in H+ based on density between H+S forest and undisturbed forest in either year. In the undisturbed forest, 59 species and 50 genera represented 30 families. The Asteraceae and Lilaceae had the highest number of species in both sampled forests, with more species of Liliaceae in the H+S plots. Micro-relief created fro pit and mound topography from uprooting of windthrown trees, shade from the slash-debris left on site from the salvage logging, and shade from the remaining overstory trees created a mosaic of environmental conditions. This environmental heterogeneity could be responsible for the mix of early (shade intolerant) and late (shade tolerant) successional herbaceous species, and a higher species richness and diversity than the undisturbed forest.

Elliott, K.J., Vose, J.M., Knoepp, J.D., Clinton, B.D. and Kloeppel, B.D. 2015. Functional role of the herbaceous layer in eastern deciduous forest ecosystems. Ecosystems. 18:221-236. (DOI: 10.1007/s10021-014-9825-x)

Abstract
The importance of the herbaceous layer in regulating ecosystem processes in deciduous forests is generally unknown. We use a manipulative study in a rich, mesophytic cove forest in the southern Appalachians to test the following hypotheses: (i) the herbaceous functional group (HFG) in mesophytic coves accelerates carbon and nutrient cycling, (ii) high litter quality input and rapid nutrient turnover associated with HFG will have a positive effect on overstory tree growth, and (iii) the HFG regulates tree regeneration with negative effects on seedling establishment due to competition for resources. We established treatment plots in a mesic, cove-hardwoods forest and removed the herbaceous flora (HR, removed twice per year) or added herbaceous organic material (OMA, once per year) for comparison to a no removal (NR) reference for a total of 14 years. The OMA treatment stimulated soil N-mineralization and increased litterfall mass and N content. OMA N-mineralization rates were more than two times greater than both the NR and HR treatments; however, we did not detect significant differences in soil CO2 efflux among treatments. Higher overstory litterfall mass and N in the OMA treatment plots indicated that overstory trees were benefiting from the enhanced soil N-mineralization. Higher overstory leaf mass and N suggests an important linkage between HR and aboveground net primary production even though this did not translate into greater tree basal area increment. We found an increase in regeneration of all tree species with HFG removal, and the response was particularly evident for Acer rubrum seedlings.

Elliott, Katherine J., Jennifer D. Knoepp, James M. Vose, and William A. Jackson. Interacting effects of wildfire severity and liming on nutrient cycling in a southern Appalachian wilderness area. 2013. Plant and Soil 366:165-183.

Abstract
Aims Wilderness and other natural areas are threatened by large-scale disturbances (e.g., wildfire), air pollution, climate change, exotic diseases or pests, and a combination of these stress factors (i.e., stress complexes). Linville Gorge Wilderness (LGW) is one example of a high elevation wilderness in the southern Appalachian region that has been subject to stress complexes including chronic acidic deposition and several wildfires, varying in intensity and extent. Soils in LGW are inherently acidic with low base cation concentrations and decades of acidic deposition have contributed to low pH, based saturation, and Ca:Al ratio. We hypothesized that wildfires that occurred in LGW followed by liming burned areas would accelerate the restoration of acidic, nutrient depleted soils. Because soils at LGW had extremely low concentrations of exchangeable Ca2+ and Mg2+ dolomitic lime was applied to further boost these cations. We evaluated the effectiveness of dolomitic lime application in restoring exchangeable Ca2+ and Mg2+ and subsequently increasing pH and Ca:Al ratio of soils and making Ca and Mg available to recovering vegetation.

Elliott, Katherine J.; Caldwell, Peter V.; Brantley, Steven T.; Miniat, Chelcy F.; Vose, James M.; Swank, Wayne T. 2017. Water yield following forest-grass-forest transitions. Hydrology and Earth System Sciences, Vol. 21(2): 17 pages.: 981-997. DOI:10.5194/hess-21-981-2017

Abstract
Many currently forested areas in the southern Appalachians were harvested in the early 1900s and cleared for agriculture or pasture, but have since been abandoned and reverted to forest (old-field succession). Land-use and land-cover changes such as these may have altered the timing and quantity of water yield (Q). We examined 80 years of streamflow and vegetation data in an experimental watershed that underwent forest–grass–forest conversion (i.e., old-field succession treatment). We hypothesized that changes in forest species composition and water use would largely explain long-term changes in Q. Aboveground biomass was comparable among watersheds before the treatment (208.3?Mgha-1), and again after 45 years of forest regeneration (217.9?Mgha-1). However, management practices in the treatment watershed altered resulting species composition compared to the reference watershed. Evapotranspiration (ET) and Q in the treatment watershed recovered to pretreatment levels after 9 years of abandonment, then Q became less (averaging 5.4% less) and ET more (averaging 4.5% more) than expected after the 10th year up to the present day. We demonstrate that the decline in Q and corresponding increase in ET could be explained by the shift in major forest species from predominantly Quercus and Carya before treatment to predominantly Liriodendron and Acer through old-field succession. The annual change in Q can be attributed to changes in seasonal Q. The greatest management effect on monthly Q occurred during the wettest (i.e., above median Q) growing-season months, when Q was significantly lower than expected. In the dormant season, monthly Q was higher than expected during the wettest months.

Ellison, A.M., M.S. Bank, B.D. Clinton, E.A. Colburn, K. Elliott, C.R. Ford, D.R. Foster, B.D. Kloeppel, J.D. Knoepp, G.M. Lovett, J. Mohan, D.A. Orwig, N.L. Rodenhouse, W.V. Sobczak, K.A. Stinson, J.K. Stone, C.M. Swan, J. Thompson, and B. Von. 2005. Loss of foundation species: consequences for the structure and dynamics of forested ecosystems. Frontiers in Ecology and the Environment 3(9): 479-486.

Abstract
In many forested ecosystems, the architecture and functional ecology of certain tree species define forest structure and their species-specific traits control ecosystem dynamics. Such foundation tree species are declining throughout the world due to introductions and outbreaks of pests and pathogens, selective removal of individual taxa, and over-harvesting. Through a series of case studies, we show that the loss of foundation tree species changes the local environment on which a variety of other species depend; how this disrupts fundamental ecosystem processes, including rates of decomposition, nutrient fluxes, carbon sequestration, and energy flow; and dramatically alters the dynamics of associated aquatic ecosystems. Forests in which dynamics are controlled by one or a few foundation species appear to be dominated by a small number of strong interactions and may be highly susceptible to alternating between stable states following even small perturbations. The ongoing decline of many foundation species provides a set of important, albeit unfortunate, opportunities to develop the research tools, models, and metrics needed to identify foundation species, anticipate the cascade of immediate, short- and long-term changes in ecosystem structure and function that will follow from their loss, and provide options for remedial conservation and management.

Ely, D. T. and J. B. Wallace. 2010. Long-term functional group recovery of lotic macroinvertebrates from logging disturbance. Canadian Journal of Fisheries and Aquatic Sciences, 67: 1126-1134.

Abstract
Clear-cut logging rapidly affects stream macroinvertebrates through substantial alteration of terrestrial-aquatic resource linkages; however, lesser known are the long-term influences of forest succession on benthic macroinvertebrate assemblages, which play key roles in stream ecosystem function. We compared secondary production and standing crops of detritus in two mountain headwater streams within Coweeta Hydrologic Laboratory, North Carolina, USA, as part of a long-term, paired-watershed investigation of macroinvertebrate recovery from whole-carchment logging.

Entrekin, S.A., J.B. Wallace, and S.L. Eggert. 2007. The response of Chironomidae (Diptera) to a long-term exclusion of terrestrial organic matter. Hydrobiologia. 575: 401-413.

Abstract
We examined the effects of a seven-year detrital exclusion on chironomid assemblages in an Appalachian headwater stream. We hypothesized that litter exclusion would lead to a reduction in all chironomids at both the subfamily and generic levels because organic matter serves as both food and habitat in these headwater streams. Tanytarsini total abundance and biomass significantly declined after litter exclusion. Before litter exclusion, Tanytarsini average abundance was 4271 + 1135 S.E. m-2 and 625 + 98 after litter exclusion. Biomass was 3.57 + 0.96 mg AFDM m-2 before litter exclusion and 1.03 + 0.9 after exclusion. In contrast, Orthocladiinae abundance and biomass did not change because a psammanophilic chironomid, Lopescladius sp., and other Orthocladiinae genera did not decline significantly. Overall chironomid taxa richness and diversity did not change as a result of litter exclusion. However, Canonical Correspondence Analysis (CCA) of genus-level biomass did show a clear separation between the litter exclusion stream and a reference stream. Separation of taxa between the two streams was due to differences in fine (r2 = 0.39) and coarse (r2 = 0.36) organic matter standing stocks and the proportion of small inorganic substrates (r2 = 0.39) present within a sample. As organic matter declined in the litter exclusion stream, overall chironomid biomass declined and the chironomid community assemblage changed. Tanytarsini were replaced by Orthocladiinae in the litter exclusion stream because they were better able to live and feed on biofilm associated with inorganic substrates.

Eppard, H. R., J.L. Horton, E.T. Nilsen, P. Galusky, and B.D. Clinton. 2005. Investigating the allelopathic potential of Kalmia latifolia L. (Ericaceae). Southeastern Naturalist. 4(3): 383-392.

Abstract
Evergreen, understory shrubs, often members of the Ericaceae, have been implicated in the suppression of tree recruitment in many ecosystems. One possible mechanism of this suppression could be an allelopathic interaction between shrubs and seedlings. We tested the allelopathic potential of Kalmia latifolia L., an important component of southern Appalachian forest understories. Aqueous extracts of soil, humus, K. latifolia litter, mixed forest floor litter, and green leaves from K. latifolia did not inhibit germination or initial root elongation of our test species Lactuca sativa L. (lettuce). Root, shoot, and total biomass were reduced in P. rigida seedlings grown in forest floor substrate collected beneath K. latifolia compared to those grown in forest substrate without K. latifolia. While these differences were not significant, they could be exacerbated in the field when seedlings are exposed to multiple stressors (reduced light, water, and nutrient availability). Our findings suggest that allelopathy is not a strong mechanism in the inhibition of canopy tree recruitment by K. latifolia.

Evans, J.O., and J.H. Patric. 1983. Harvest trees, reap water. Journal of Soil and Water Conservation 38: 390-392.

Abstract
The relationship of timber harvesting to water yield is discussed by the authors. They trace the development of current knowledge that clearcutting increases water yield from the earlier idea that an intact forest maximizes water yield. Experimental results from eastern and western watersheds are presented, along with implications for timber management as a tool for manipulating water yield.

Evans, Sakura R., Jensen-Ryan, Danielle. 2017. Exurbanization and Its Impact on Water Resources: Stream Management among Newcomer and Generational Landowners in Southern Appalachia Appalachian Journal 44(1-2)

Abstract
Referred to as exurbanization, amenity migration, counter-urbanization, rural sprawl, or neo-rural migration, the influx of urban migrants into rural communities has been increasingly studied over the last 50 years, both domestically and internationally. Exurbanization, a term Spectorsky coined in 1955, represents a “rural restructuring” as rural communities, environments, and economies shift from agricultural, or productivist, to other post-productivist or neo-productivist landscapes. While the concept of exurbanization conforms to the general idea of “sprawl,” Cadieux explains that the characterizing feature of exurbanization that differentiates it from unplanned residential development on the urban periphery is the amount of land. She argues that exurban development is desirable specifically because it involves lowpopulation density and large parcel sizes, and it is the “material and ideological benefits of sprawling nature [that] attract amenity migrants to exurban landscapes.” Exurbanization is also the fastest growing manner of land acquisition in the United States and a primary driver of economies transitioning from natural resource extraction to the service industry. 5 Scholars have expressed growing concern over the impacts of exurbanization on environmental resources,particularly its impacts on water as increased population density applies pressure on the regional water supply due to increased water consumption. Furthermore, as residential and commercial development increase within a region to accommodate growing populations of retirees and amenity migrants, increased impervious surfaces, stream sedimentation, and erosion have resulted in impaired stream health and water quality. Yet, one of the most serious threats to stream health and water quality from exurbanization is the impact of land use decision-making at the parcel level. As more rural land becomes fragmented and sold, more landowners own smaller parcels, thus intensifying land management on regional resources. In particular, stream management by private landowners, specifically the management of riparian zones, or the area between land and rivers or streams, has been highlighted as a critical area for research and restoration. Southern Appalachia is a water-rich region with an extensive network of streams and rivers that effectively function as a water tower for the Southeastern United States. The region is also undergoing rapid exurban development, providing an excellent opportunity to determine if, and how, exurbanization is having an impact on the regional environment. When viewed as a watershed, parcel level decision-making can directly impact stream health and water quality. Therefore, we chose to examine intra-community patterns of stream management among two populations of landowners in the same community by surveying values about property and water rights, preference for stream appearance, perceptions of stream health, and stream management practices.

F. Thigpen, T & J. Humphries, W & Maerz, John. (2010). Effectiveness of using artificial shelters to sample arboreal green salamander populations in the Blue Ridge Mountains of Georgia and North Carolina. Herpetological Review. 41. 159-162.

Facey, D.E., Grossman, G.D. 1990. The Metabolic Cost of Maintaining Position for Four North American Stream Fishes: Effects of Season and Velocity. Physiological Zoology, 63(4): 757-776.

Abstract
We used a swimming respirometer to measure oxygen consumption (i.e. metabolic cost) of four species of stream fishes while they held position at different velocities. We tested naturally acclimatized indivduals during during spring, summer, fall, and winter at seasonal temperatures and photoperiods. Rosyside dace (Clinostomus funduloides) longnose dace (Rhinichtys cataractae) cottled sculpin (Cottus bairdi) and juvenile rainbow trout (Oncorhynchus mykiss) all showed seasonal changes in oxygen consumption. Seasonal changes in standard metabolic rates seemed to be influenced by changes in reproductive condition as well as ambient temperature. The metabolic cost of maintaining position for rainbow trout and rosyside dace generally increased with velocity. At velocities below eight body lenghts per second, longnose dace did not exhibit a significant change in oxygen consumption, because they held position without swimming. At higher velocities, however, longnose dace swam to maintain their position and oxygen consumption increased rapidly. Mottled sculpin held position without swimming and therefore showed little or no change in enegy use with charging current velocity.

Facey, D.E., Grossman, G.D. 1992. The relationship between water velocity, energetic costs, and microhabitat use in four North American stream fishes. Hydrobiologia, 239: 1-6

Abstract
We employed field and laboratory data to test the hypothesis that microhabitat use by rainbow trout (Oncorhynchus mykiss), rosyside dace (Clinostomus funduloides), longnose dace (Rhinichthys cataractae) and mottled sculpin (Cottus bairdi) was affected by energetic constraints. Both rainbow trout and rosyside dace occupied water-column microhabitats in Coweeta Creek, North Carolina, U.S.A. These species were over-represented at velocities requiring lower rates of oxygen consumption, as predicted by an energetic cost hypothesis. Morphological and behavioral adaptations of the two benthic species (mottled sculpin and longnose dace) enabled them to hold position over a wide range of velocities without significant changes in oxygen consumption. Focal point velocities of longnose dace were not significantly different from those available, suggesting a lack of velocity preference. Mottled sculpin, however, consistently were over-represented at low velocities, even though oxygen consumption data showed that energetic costs were not decreased by occupying these microhabitats. Our results indicate that microhabitat use by rainbow trout and rosyside dace is consistent with predictions of an energetic cost hypothesis, whereas the morphological adaptations of longnose dace and mottled sculpin minimize the constraints of energetic costs in microhabitat selection.

Fahey, T. J. 1988. Forest hydrology and ecology at Coweeta. The Quarterly Review of Biology 63: 478-479.

Abstract
A review of the Coweeta Symposium volume.

Fang, Y., Sun, G., Caldwell, P., McNulty, S.G., Noormets, A., Domec, J.-C., King, J., Zhang, Z., Zhang, X., Lin, G., Zhou, G., Xiao, J. and Chen, J. 2015. Monthly land cover-specific evapotranspiration models derived from global eddy flux measurements and remote sensing data. Ecohydrology. (DOI: 10.1002/eco.1629)

Abstract
Evapotranspiration (ET) is arguably the most uncertain ecohydrologic variable for quantifying watershed water budgets. Although numerous ET and hydrological models exist, accurately predicting the effects of global change on water use and availability remains challenging because of model deficiency and/or a lack of input parameters. The objective of this study was to create a new set of monthly ET models that can better quantify landscape-level ET with readily available meteorological and biophysical information. We integrated eddy covariance flux measurements from over 200 sites, multiple year remote sensing products from the Moderate Resolution Imaging Spectroradiometer (MODIS), and statistical modelling. Through examining the key biophysical controls on ET by land cover type (i.e. shrubland, cropland, deciduous forest, evergreen forest, mixed forest, grassland, and savannas), we created unique ET regression models for each land cover type using different combinations of biophysical independent factors. Leaf area index and net radiation explained most of the variability of observed ET for shrubland, cropland, grassland, savannas, and evergreen forest ecosystems. In contrast, potential ET (PET) as estimated by the temperature-based Hamon method was most useful for estimating monthly ET for deciduous and mixed forests. The more data-demanding PET method, FAO reference ET model, had similar power as the simpler Hamon PET method for estimating actual ET. We developed three sets of monthly ET models by land cover type for different practical applications with different data availability. Our models may be used to improve water balance estimates for large basins or regions with mixed land cover types.

Farmers Federation News. 1951.The Coweeta story. Farmers Federation News 31(12): 9, 44-45, 48.

Abstract
Reasons for establishment of the Coweeta Hydrologic Laboratory are given, the research area is described, and studies concerning the effects of mountain farming, woodland grazing, and cutting of vegetation on streamflow are discussed.

Farrell, K.J., A.D. Rosemond, J.S. Kominoski, S.M. Bonjour, J. Rüegg, L.E. Koenig, C.L. Baker, M.T. Trentman, T.K. Harms, W.H. McDowell. 2018. Variation in detrital resource stoichiometry signals differential carbon to nutrient limitation for stream consumers across biomes. Ecosystems. 21: 1676-1691.

Abstract
Stoichiometric ratios of resources and consumers have been used to predict nutrient limitation across diverse terrestrial and aquatic ecosystems. In forested headwater streams, coarse and fine benthic organic matter (CBOM, FBOM) are primary basal resources for the food web, and the distribution and quality of these organic matter resources may therefore influence patterns of secondary production and nutrient cycling within stream networks or among biomes. We measured carbon (C), nitrogen (N), and phosphorus (P) content of CBOM and FBOM and calculated their stoichiometric ratios (C/N, C/P, N/P) from first- to fourth-order streams from tropical montane, temperate deciduous, and boreal forests, and tallgrass prairie, to compare the magnitude and variability of these resource types among biomes. We then used the ratios to predict nutritional limitations for consumers of each resource type. Across biomes, CBOM had consistently higher %C and %N, and higher and more variable C/N and C/P than FBOM, suggesting that microbial processing results in more tightly constrained elemental composition in FBOM than in CBOM. Biome-specific differences were observed in %P and N/P between the two resource pools; CBOM was lower in %P but higher in N/P than FBOM in the tropical montane and temperate deciduous forest biomes, while CBOM was higher in %P but similar in N/P than FBOM in the grassland and boreal forest biomes. Stable 13C isotopes suggest that FBOM likely derives from CBOM in tropical and temperate deciduous forest, but that additional non-detrital components may contribute to FBOM in boreal forests and grasslands. Comparisons of stoichiometric ratios of CBOM and FBOM to estimated needs of aquatic detritivores suggest that shredders feeding on CBOM are more likely to experience nutrient (N and/or P) than C limitation, whereas collector–gatherers consuming FBOM are more likely to experience C than N and/or P limitation. Our results suggest that differences in basal resource elemental content and stoichiometric ratios have the potential to affect consumer production and ecosystem rates of C, N, and P cycling in relatively consistent ways across diverse biomes.

Fausch, K.D., Taniguchi, Y., Nakano, S. Grossman, G.D. Townsend, C.R. 2001.Flood Disturbance Regimes Influence Rainbow Trout Invasion Success Among Five Holarctic Regions. Ecological Applications, 11(5): 1438-1455

Abstract
There is growing awareness that predicting biological invasions will require the development of conceptual models for specific taxa at appropriate scales. Salmonids are ideal taxa for testing factors that influence invasions, because large numbers have been introduced worldwide for long periods and their ecology is well known. We evaluated the hypothesis that, among regions with suitable water temperatures, environmental resistance from flood disturbances that wash away trout fry strongly influence invasion success of rainbow trout (Oncorhynchus mykiss), the most widely introduced fish species.We predicted that flow regimes in regions where rainbow trout invasions are successful would match those in their native range and would differ from those in regions where invasions are moderately successful or failed. We tested six specific predictions about how timing, predictability, frequency, duration, and annual variability of floods, as well as timing of low flows, will differ relative to timing of rainbow trout fry emergence among five Holarctic regions. Analysis of hydrologic regimes for eight rivers each in the native range (Pacific Coast) and four regions where rainbow trout invasions varied from highly successful (Southern Appalachians) to moderate (Colorado, USA, and Hokkaido Island, Japan) or failed (Honshu Island) showed that winter flooding and summer low flows in Pacific Coast rivers that favor spring emergence of rainbow trout were closely matched by Southern Appalachian flow regimes. In contrast, the other three regions had spring or summer flooding that hampered rainbow trout recruitment to different degrees, and winter low flows. Rainbow trout invasion success was best explained by a match between timing of fry emergence and months of low flood probability. Alternatively, cold water temperatures, which hamper reproduction, and biotic interactions with brown trout (Salmo trutta) and whirling disease parasites may account for low invasion success in European regions. However, differences in genetic makeup of donor stocks and propagule pressure are unlikely mechanisms to explain invasions. Understanding how abiotic disturbances interact with timing of critical life history events to limit nonnative species will help ecologists develop more robust theories to predict invasion success.

Fausch, K.D., Y. Taniguchi, S. Nakano, G.D.Grossman, and C.R. Townsend. 2001. Flood Disturbance Regimes Influence Ranibow Trout Invasion Success Among Five Holarctic Regions. Ecological Applications. 11(5): 1438-1455.

Abstract
There is growing awareness that predicting biological invasions will require the development of conceptual models for specific taxa at appropriate scales. Salmonids are ideal taxa for testing factors that influence invasions, because large numbers have been introduced worldwide for long periods and their ecology is well known. We evaluated the hypothesis that, among regions with suitable water temperatures, environmental resistance from flood disturbances that wash away trout fry strongly influence invasion success of rainbow trout (Oncorhynchus mykiss), the most widely introduced fish species. We predicted that flow regimes in regions where rainbow trout invasions are successful would match those in their native range and would differ from those in regions where invasions are moderately successful or failed. We tested six specific predictions about how timing, predictability, frequency, duration, and annual variability of floods, as well as timing of low flows, will differ relative to timing of rainbow trout fry emergence among five Holarctic regions. Analysis of hydrologic regimes for eight rivers each in the native range (Pacific Coast) and four regions where rainbow trout invasions varied from highly successful (Southern Appalachians) to moderate (Colorado, USA, and Hokkaido Island, Japan) or failed (Honshu Island) showed that winter flooding and summer low flows in Pacific Coast rivers that favor spring emergence of rainbow trout were closely matched by Southern Appalachian flow regimes. In contrast, the other three regions had spring or summer flooding that hampered rainbow trout recruitment to different degrees, and winter low flows. Rainbow trout invasion success was best explained by a match between timing of fry emergence and months of low flood probability. Alternatively, cold-water temperatures, which hamper reproduction, and biotic interactions with brown trout (Salmo trutta) and whirling disease parasites may account for low invasion success in European regions. However, differences in genetic makeup of donor stocks and propagule pressure are unlikely mechanisms to explain invasions. Understanding how abiotic disturbances interact with timing of critical life history events to limit nonnative species will help ecologists develop more robust theories to predict invasion success.

Fenn, M.E., Poth, M.A., Aber, J.D., Baron, J.S., Bormann, B.T., Johnson, D.W., Lemly, A.D., McNulty, S.G., ; Ryan, D.F., Stottlemyer, R., 1998. Nitrogen Excess in North American Ecosystems: Predisposing Factors, Ecosystem Responses, and Management Strategies. Ecological Applications, Vol 8:3, Aug. 1998, p. 706-733, Ecological Society of America

Abstract
Most forests in North America remain nitrogen limited, although recent studies have identified forested areas that exhibit symptoms of N excess, analogous to overfertilization of arable land. Nitrogen excess in watersheds is detrimental because of disruptions in plant/soil nutrient relations, increased soil acidification and aluminum mobility, increased emissions of nitrogenous greenhouse gases from soil, reduced methane consumption in soil, decreased water quality, toxic effects on freshwater biota, and eutrophication of coastal marine waters. Elevated nitrate (NO]) loss to groundwater or surface waters is the primary symptom of N excess. Additional symptoms include increasing N concentrations and higher N:nutrient ratios in foliage (i.e., N:Mg, N:P), foliar accumulation of amino acids or NO], and low soil C:N ratios. Recent nitrogen-fertilization studies in New England and Europe provide preliminary evidence that some forests receiving chronic N inputs may decline in productivity and experience greater mortality. Long-term fertilization at Mount Ascutney, Vermont, suggests that declining and slow N-cycling coniferous stands may be replaced by fast-growing and fast N-cycling deciduous forests. Symptoms of N saturation are particularly severe in high-elevation, nonaggrading spruce-fir ecosystems in the Appalachian Mountains and in eastern hardwood watersheds at the Fernow Experimental Forest near Parsons, West Virginia. In the Los Angeles Air Basin, mixed conifer forests and chaparral watersheds with high smog exposure are N saturated and exhibit the highest streamwater NO] concentrations for wildlands in North America. High-elevation alpine watersheds in the Colorado Front Range and a deciduous forest in Ontario, Canada, are N saturated, although N deposition is moderate (~8 kg•ha-!•yr!). In contrast, the Harvard Forest hardwood stand in Massachusetts has absorbed >900 kg Nlha during 8 yr of N amendment studies without significant NO] leaching, illustrating that ecosystems vary widely in the capacity to retain N inputs. Overly mature forests with high N deposition, high soil N stores, and low soil C:N ratios are prone to N saturation and NO] leaching. Additional characteristics favoring low N retention capacity include a short growing season (reduced plant N demand) and reduced contact time between drainage water and soil (i.e., porous coarse-textured soils, exposed bedrock or talus). Temporal patterns of hydrologic fluxes interact with biotic uptake and internal cycling patterns in determining ecosystem N retention. Soils are the largest storage pool for N inputs, although vegetation uptake is also important. Recent studies indicate that nitrification may be widespread in undisturbed ecosystems, and that microbial assimilation of NO] may be a significant N retention mechanism, contrary to previous assumptions. Further studies are needed to elucidate the sites, forms, and mechanisms ofN retention and incorporation into soil organic matter, and to test potential management options for mitigating N losses from forests. Implementation of intensive management practices in N-saturated ecosystems may only be feasible in high-priority areas and on a limited scale. Reduction of N emissions would be a preferable solution, although major reductions in the near future are unlikely in many areas due to economic, energy-use, policy, and demographic considerations.

Ferguson, P. F.B., Conroy, M. J. and Hepinstall-Cymerman, J. (2017), Assessing conservation lands for forest birds in an exurban landscape. Jour. Wild. Mgmt., 81: 1308–1321. doi:10.1002/jwmg.21295

Abstract
Exurban development is the fastest growing type of land use in the United States and is prominent in the southern Appalachian region. A potential consequence of exurban development is the loss and fragmentation of wildlife habitat. We used a Bayesian model that accounts for false positive and false negative detections to make inferences about how the occupancy of 6 forest-dwelling, Neotropical migrant birds is related to multi-scale attributes of exurban development on land managed under 3 different conservation frameworks: national forest, land trust, or unprotected property in Macon County, North Carolina, USA during 2 breeding seasons. We performed Bayesian model selection and model averaging with a Bayesian Information Criterion weights approximation, and we evaluated models’ predictive ability. We compared results from our occupancy model to those from a traditional model assuming data had no false positives. Results indicated that landscape- and local-scale covariates were more strongly related to posterior occupancy probabilities than site-scale covariates and that landscape composition and elevation were more strongly associated with occupancy probabilities than configuration. In particular, occupancy had a positive relationship with elevation and percent forest and a negative relationship with percent development. The black-throated blue warbler (Setophaga caerulescens) and wood thrush (Hylocichla mustelina) had the lowest posterior occupancy probabilities of the focal species, suggesting that these species may need particular conservation attention. National forest sites had high occupancy, but land trust sites exhibited patterns similar to unprotected sites. Our findings can provide guidance to county land use planners and land trusts as they respond to exurban development. Also, our study demonstrates the application of an improved occupancy model that can generate more accurate inference by accounting for both types of imperfect detection while describing heterogeneity across sites and survey occasions.

Ferguson, P.F., Conroy, M. and Hepinstall-Cymerman, J. 2015. Occupancy models for data with false positive and false negative errors and heterogeneity across sites and surveys. Methods in Ecology and Evolution. (DOI: 10.1111/2041-210X.12442)

Abstract
1. False positive detections, such as species misidentifications, occur in ecological data, although many models do not account for them. Consequently, these models are expected to generate biased inference. 2. The main challenge in an analysis of data with false positives is to distinguish false positive and false negative processes while modelling realistic levels of heterogeneity in occupancy and detection probabilities without restrictive assumptions about parameter spaces. 3. Building on previous attempts to account for false positive and false negative detections in occupancy models, we present hierarchical Bayesian models that utilize a subset of data with either confirmed detections of a species’ presence (CP model) or both confirmed presences and confirmed absences (CACP model). We demonstrate that our models overcome the challenges associated with false positive data by evaluating model performance in Monte Carlo simulations of a variety of scenarios. Our models also have the ability to improve inference by incorporating previous knowledge through informative priors.4. We describe an example application of the CP model to quantify the relationship between songbird occupancy and residential development, plus we provide instructions for ecologists to use the CACP and CP models in their own research.5. Monte Carlo simulation results indicated that, when data contained false positive detections, the CACP and CP models generated more accurate and precise posterior probability distributions than a model that assumed data did not have false positive errors. For the scenarios we expect to be most generally applicable, those with heterogeneity in occupancy and detection, the CACP and CP models generated essentially unbiased posterior occupancy probabilities. The CACP model with vague priors generated unbiased posterior distributions for covariate coefficients. The CP model generated unbiased posterior distributions for covariate coefficients with vague or informative priors, depending on the function relating covariates to occupancy probabilities. We conclude that the CACP and CP models generate accurate inference in situations with false positive data for which previous models were not suitable.

Ferguson, P.F., Conroy, M., Chamblee, J.F. and Hepinstall-Cymerman, J. 2015. Using structured decision making with landowners to address privateforest management and parcelization: balancing multiple objectives andincorporating uncertainty. Ecology and Society. 20 (4):27

Abstract
Parcelization and forest fragmentation are of concern for ecological, economic, and social reasons. Efforts to keep large, private forests intact may be supported by a decision-making process that incorporates landowners’ objectives and uncertainty. We used structured decision making (SDM) with owners of large, private forests in Macon County, North Carolina. Macon County has little land use regulation and a history of discordant, ineffective attempts to address land use and development. We worked with landowners to define their objectives, identify decision options for forest management, build a Bayesian decision network to predict the outcomes of decisions, and determine the optimal and least-desirable decision options. The optimal forest management options for an average, large, forested property (30 ha property with 22 ha of forest) in Macon County was crown-thinning timber harvest under the Present-Use Value program, in which enrolled property is taxed at the present-use value (growing timber for commercial harvest) rather than full market value. The least-desirable forest management actions were selling 1 ha and personal use of the forest (e.g., trails, firewood) with or without a conservation easement. Landowners reported that they enjoyed participating in the project (85%) and would reconsider what they are currently doing to manage their forest (69%). The decision that landowners initially thought would best meet their objectives did not match results from the decision network. This highlights the usefulness of SDM, which typically has been applied to decision problems involving public resources.

Findlay, S., and J.L. Meyer. 1984. Significance of bacterial biomass and production as an organic carbon source in lotic detrital systems. Bulletin of Marine Science 35(3): 318-325.

Abstract
Bacteria are an organic carbon source for secondary consumers in detritus-based ecosystems, but few measurements of bacterial production are available. The use of tritiated thymidine has made possible measurement of bacterial production. We have found bacterial production in sediments and on particulate detritus of two lotic ecosystems to range from 0.01-10.0 mg C/m2/d. These rates are only a small proportion of carbon entering these systems. Also, bacterial carbon production is small relative to total carbon mineralization, indicating either that other organisms are responsible for the bulk of catabolic activity or that bacterial utilization of detritus in these systems is very inefficient in the sense that the majority of carbon assimilated is respired rather than allocated to new growth.

Findlay, S., J.L. Meyer, and P.J. Smith. 1986. Incorporation of microbial biomass by Peltoperla sp. (Plecoptera) and Tipula sp. (Diptera). Journal of North American Benthological Society 5(4): 306-310.

Abstract
The quantitative contribution of microbial carbon to the nutrition of aquatic detritivores previously has not been measured. Using radiotracers to specifically label bacteria and fungi on leaf litter, we determined the rate of incorporation of bacteria and a hyphomycete by larvae of stonefly and incorporation of bacteria by larvae of cranefly. Incorporation of bacterial carbon accounted for less than 1% of the carbon respired by either insect. Incorporation of fungal carbon was greater but still only 25% of the carbon respired by the stonefly larva.

Fitzgerald, J.W., and M.B. Watwood. 1988. Isolation and turnover of organic matter covalently labeled with 35 Smethionine. Soil Biol. Biochem. 20: 833-838.

Abstract
None

Fitzgerald, J.W., and M.E. Watwood. 1988. Amino-acid metabolism in forestsoil - isolation and turnover of organic matter covalently labelled with35S-methionine. Soil Biology and Biochemistry 20(6): 833-838.

Abstract
Interconversions between sulfate and organic S will influence the mobility ofinorganic sulfate, a major anionic component of acidic precipitation. Organic matter was extracted from the O2 horizon of a hardwood forest and exposed to 35S-methionine for 18 h to allow incorporation of the amino-acid into the extract. This material was chemically recalcitrant, requiring treatment for 6 hat 121+C with 6 M NaOH for complete release of the incorporated methionine. Aand B horizon soils from several forests were exposed to labelled material following dialysis to remove unlabelled components and a minor 35S-labelled component. Samples began to release 35S-methionine after 48 h. Further metabolism of this amino-acid included mineralization and conversion to cysteine. A portion of the sulfate-S from mineralization was incorporated into organic matter and recovered only by acid and alkali extraction. 35S-labelled methionine and cysteine were also found in these latter fractions, indicating that these amino-acids had been directly incorporated into organic material during exposure.

Fitzgerald, J.W., and T.C. Strickland. 1987. Mineralization of organic sulphur in the O2 horizon of a hardwood forest: involvement of sulphatase enzymes. Soil Biology and Biochemistry 19(6): 779-781.

Abstract
Sulphate-S is accumulated in organic matter in soil of deciduous forests. Once organic-S is formed, it can become mineralized by one of two mechanisms: oxidation of the carbon skeleton to yield energy and carbon for biosynthesis with SO4 being released as a by-product, or directly after hydrolysis of ester-sulphate linkages comprising the organic-S. In order to obtain direct evidence for the involvement of enzymes, S mineralization occurring in organic matter extracts was assayed in the presence and absence of PO4 and sodium azide. The latter compound inhibits microbial growth but not sulphatase activity. Because SO4 was released in the presence of azide, enzymes must have been present in the extract before incubation. Further, microbial growth was not required to sustain enzyme activity, suggesting that S mineralization is mediated by preformed, possibly extracellular, enzymes.

Fitzgerald, J.W., and T.L. Andrew. 1984. Mineralization of methionine sulfur in soils and forest floor layers. Soil Biology and Biochemistry 16(6): 565-570.

Abstract
A1-horizon soils and O1, O2 forest floor layers from a mixed mature hardwood forest rapidly converted methionine-S to readily-available (salt-extractable) and less readily-available (acid- and base-extractable) inorganic sulphate. This latter conversion represents the incorporation into organic matter of a portion of the SO4 released by mineralization. On a dry weight basis, the O2 layer of the forest floor was the most active with respect to both conversions. Moreover, capacities for mineralization and SO4 incorporation decreased with increasing sample depth within the mineral horizon. Both conversions were dependent upon temperature and duration of incubation.

Fitzgerald, J.W., and T.L. Andrew. 1985. Metabolism of methionine in forest floor layers and soil: influence of sterilization and antibiotics. Soil Biology and Biochemistry 17(6): 881-883.

Abstract
Antibiotics were added to forest soils to separate and define incorporation and mineralization processes involving the amino acid L-methionine. Data presented reveal that both processes are microbially mediated.

Fitzgerald, J.W., D.D. Hale, and W.T. Swank. 1988. Sulphur-containing amino acid metabolism in surface horizons of a hardwood forest. Soil Biology and Biochemistry 20(6): 825-831.

Abstract
The O1, O2 and A1 horizons of a hardwood forest mineralized and incorporated into organic matter 35S-labelled cysteine and methionine. Based upon seasonal assays, mineralization was the dominant process for cysteine. With methionine, the reverse was true except in the A1 horizon. Analysis for existing amounts of organic S revealed that carbon-bonded S was a major component throughout the year in all horizons. This S pool consisted of sulphonate S and amino acid S. Sulphonate represented 59, 44 and 28% of total S in the O1, O2 and A1 horizons, respectively. Amino acid S comprised 22, 24 and 15% of the total S in these horizons. In samples, decreases in existing amounts of amino acid S coincided with increases in cysteine mineralization suggesting that cysteine is an important component of the S pool in the A1 horizon.

Fitzgerald, J.W., J.T. Ash, T.C. Strickland, and W.T. Swank. 1983. Formation of organic sulfur in forest soils: a biologically mediated process. Canadian Journal of Forest Research 13: 1077-1082.

Abstract
The ability of forest soils to incorporate sulfur from added inorganic sulfate into salt-extractable and non salt-extractable forms was investigated. At least 65 percent of the added sulfate was adsorbed while 8 to 27 percent of the sulfate added was recovered only after treatment of salt-extracted samples with acid and base. The incorporation of sulfur into this latter fraction was incubation time, temperature and depth dependent, and exhibited both spatial as well as seasonal variation in samples taken along a transect of one of the watersheds. Sulfur incorporation was inhibited by sodium azide, erythromycin and candicidin, suggesting that the incorporation of sulfur into the non salt-extractable fraction is mediated by bacteria and fungi.

Fitzgerald, J.W., M.E. Watwood, and F.A. Rose. 1985. Forest floor and soil arylsulphatase: hydrolysis of tyrosine sulphate, an environmentally relevant substrate for the enzyme. Soil Biology and Biochemistry 17(6): 885-887.

Abstract
Arylsulphatase is an enzyme widespread in nature that catalyzes the release of SO4 from sulfate esters of simple phenols. Although this enzyme is found extensively in soil, its activity has not been successfully correlated with S mineralization rates. A typical assay substance is not found in nature. Various tests show that microbial growth was necessary to sustain enzyme production and activity while fungal growth was not.

Fitzgerald, J.W., T C. Strickland, and W.T. Swank. 1982. Metabolic fate of inorganic sulfate in soil samples from undisturbed and managed forest ecosystems. Soil Biology and Biochemistry 14: 529-536.

Abstract
Surface soils from four watersheds located at the Coweeta Hydrologic Laboratory were found to rapidly convert exogenous 35SO42- into nonextractable ester sulphate and carbon bonded-sulphur. A substantial proportion of the added 35SO42- remained adsorbed in all samples but was completely released after sequential leaching with 1M Na2SO4, NaH2PO4 and LiCl. This extraction procedure also released a number of 35S-labeled metabolites and some of these have been identified on the basis of co-electrophoresis and co-chromatography with authentic standards. Recoveries of 35S suggest that all samples were capable of volatilizing some of the added SO42- but only after prolonged incubation. The results support the possibility that S accumulation in these watersheds is related to SO42- adsorption. However, the results also indicate that incorporation of S into non-extractable organic forms is a possibility which must be addressed in future attempts to fully explain this phenomenon.

Fitzgerald, J.W., T.C. Strickland, and J.T. Ash. 1985. Isolation and partial characterization of forest floor and soil organic sulfur. Biogeochemistry 1: 155-167.

Abstract
The formation of organic sulfur from inorganic sulfate was investigated in hardwood forest floor and mineral horizons. All samples converted sulfate-sulfur into a non-salt extractable form which was recoverable only under conditions which release organic matter. This conversion was inhibited by azide, by erythromycin, candicidin, chloramphenicol and tetracycline. The form of sulfur generated in the O2 forest floor layer and in A1-horizon soil was characterized as having an average C:N:S ratio of 103:6:1. The ester sulfate content of the O2 extract was about 60%. Reduction yielded lower estimates of ester sulfate for two of the three soil extracts analyzed. The electrophoretic heterogeneity of all extracts suggests that some may contain stable ester linkages that hydrolyze only after prolonged treatment and that the standard procedure for hydriodic acid reduction may provide conditions of temperature and contact time with the acid which are insufficient for the release of sulfate from these esters.

Fitzgerald, J.W., T.L. Andrew, and W.T. Swank. 1984. Availability of carbon-bonded sulfur for mineralization in forest soils. Canadian Journal of Forest Research 14: 839-843.

Abstract
The capacities of soil from hardwood, clear-cut, and pine forests to mineralize, adsorb, and incorporate into organic matter carbon-bonded sulfur in the form of L-methionine was investigated. These soils adsorbed and incorporated between 40 and 66% of this amino acid within a 0.5-h incubation period, but much of the immobilized sulfur was mineralized after 48 h incubation. On the forested watershed, the O2 layer exhibited the highest levels of activity. Incorporation of methionine into organic matter was complete within about 12 h of incubation and was inhibited by pretreatment of the samples with sodium azide; a general inhibitor of cell respiration. The capacities for methionine incorporation, determined by laboratory assays, complement observations of the high levels of carbon bonded sulfur found in situ in forest litter and soil.

Fiumera, A.C., B.A. Porter, G.D. Grossman, and J.C. Avise. 2002. Intensive genetic assessment of the mating system and reproductive success in a semi-closed population of the mottled sculpin, Cottus bairdi. Molecular Ecology. 11: 2367-2377.

Abstract
Most genetic surveys of parentage in nature sample only a small fraction of the breeding population. Here we apply microsatellite markers to deduce the genetic mating system and assess the reproductive success of females and males in an extensively collected, semiclosed stream population of the mottled sculpin fish, Cottus bairdi. In this species, males guard nest rocks where females deposit the eggs for fertilization. The potential exists for both males and females to mate with multiple partners and for males to provide parental care to genetically unrelated offspring. Four hundred and fifty-five adults and subadults, as well as 1259 offspring from 23 nests, were genotyped at five polymorphic microsatellite loci. Multilocus maternal genotypes, deduced via genetic analyses of embryos, were reconstructed for more than 90% of the analysed nests, thus allowing both male and female reproductive success to be estimated accurately. There was no genetic evidence for cuckoldry, but one nest probably represents a takeover event. Successful males spawned with a mean of 2.8 partners, whereas each female apparently deposited her entire clutch of eggs in a single nest (mean fecundity = 66 eggs/female). On average, genetically deduced sires and dams were captured 1.6 and 9.3 meters from their respective nests, indicating little movement by breeders during the spawning season. Based on a 'genetic mark-recapture' estimate, the total number of potentially breeding adults (c. 570) was an order-of-magnitude larger than genetically based estimates of the effective number of breeders (c. 54). In addition, significantly fewer eggs per female were deposited in single than in multidam nests. Not only were perceived high-quality males spawning with multiple partners, but they were receiving more eggs from each female.

Flebbe, P.A. 1999. Trout use of woody debris and habitat in Wine Spring Creek, North Carolina. Forest Ecology and Management. 114: 367-376.

Abstract
Wine Spring Creek basin, in the mountains of North Carolina's Nantahala National Forest, is an ecosystem management demonstration site, in which ecological concepts for management and restoration are tested. Large woody debris (LWD) is an important link between streams and the adjacent riparian forest, but evidence for the connection between LWD and trout in southern Appalachian streams is limited. Woody debris loadings, trout habitat, and brook trout (Salvelinus fontinalis) and rainbow trout (Oncorhynchus mykiss) were inventoried for the entire 9.8 km that trout occupy in Wine Spring Creek. Compared to two reference streams in North Carolina old-growth forests, Wine Spring Creek had less LWD, evidence of conditions associated with mid-successional riparian forests. More units in Wine Spring Creek lacked LWD altogether and accumulations of two or more pieces of LWD were less common than was the case in the reference watersheds. On average, about 71% of pools and riffles in Wine Spring Creek were occupied by trout, compared to about 90% in reference streams. Trout nearly always occupied pools with at least two pieces of LWD, but rates of occupancy for pools with one or no LWD pieces and riffles were unusually low compared to reference streams. Habitats on the lower and middle reaches on the mainstem of Wine Spring Creek had highest trout numbers and were nearly always occupied by trout. In these reaches, riparian ages were older and stream habitat had abundant LWD or boulder substrate. Upper reaches of Wine Spring Creek and its tributaries, however, were characterized by less mature riparian forest, less LWD and little boulder substrate, low rates of trout occupancy, and lower trout numbers. These conditions are the basis for an LWD addition experiment in headwater reaches.

Follstad Shah, J., J. Kominoski, M. Ardon, W. Dodds, M. Gessner, N. Griffiths, C. Hawkins, A. Lecerf, C. LeRoy, D. Manning, S. Johnson, A. Rosemond, R. Sinsabaugh, C. Swan, J. Webster, and L. Zeglin. (2017), Global synthesis of the temperature sensitivity of leaf litter breakdown in streams and rivers. Global Change Biology doi: 10.1111/gcb.13609.

Abstract
Streams and rivers are important conduits of terrestrially derived carbon (C) to atmospheric and marine reservoirs. Leaf litter breakdown rates are expected to increase as water temperatures rise in response to climate change. The magnitude of increase in breakdown rates is uncertain, given differences in litter quality and microbial and detritivore community responses to temperature, factors that can influence the apparent temperature sensitivity of breakdown and the relative proportion of C lost to the atmosphere vs. stored or transported downstream. Here, we synthesized 1025 records of litter breakdown in streams and rivers to quantify its temperature sensitivity, as measured by the activation energy (Ea, in eV). Temperature sensitivity of litter breakdown varied among twelve plant genera for which Ea could be calculated. Higher values of Ea were correlated with lower-quality litter, but these correlations were influenced by a single, N-fixing genus (Alnus). Ea values converged when genera were classified into three breakdown rate categories, potentially due to continual water availability in streams and rivers modulating the influence of leaf chemistry on breakdown. Across all data representing 85 plant genera, the Ea was 0.34 ± 0.04 eV, or approximately half the value (0.65 eV) predicted by metabolic theory. Our results indicate that average breakdown rates may increase by 5–21% with a 1–4 °C rise in water temperature, rather than a 10–45% increase expected, according to metabolic theory. Differential warming of tropical and temperate biomes could result in a similar proportional increase in breakdown rates, despite variation in Ea values for these regions (0.75 ± 0.13 eV and 0.27 ± 0.05 eV, respectively). The relative proportions of gaseous C loss and organic matter transport downstream should not change with rising temperature given that Ea values for breakdown mediated by microbes alone and microbes plus detritivores were similar at the global scale.

Ford, C. R., E. S. Minor, G. A. Fox. 2010. Long-term effects of fire and fire-return interval on population structure and growth of longleaf pine (Pinus palustris). Canadian Journal of Forest Research, 40:1410-1420.

Abstract
We investigated the effect of fire and fire frequency on stand structure and longleaf pine (Pinus palustris P. Mill.) growth and population demography in an experimental research area in a southwest Florida sandhill community. Data were collected from replicated plots that had prescribed fire-return intervals of 1, 2, 5, or 7 years or were left unburned. Experimental treatment burns have been ongoing since 1976. Plots were sampled to estimate species distribution, stand structure, and longleaf pine density in four developmental stage classes: grass, bolting, small tree, and large tree. Tree-ring growth measurements in combination with burn history were used to evaluate the effects of fire and fire-return interval on basal area increment growth. Fire-return interval impacted stand structure and longleaf pine population structure. Our results suggest that recruitment from the bolting stage to later stages may become adversely affected with very frequent fires (e.g., every 1 or 2 years). Although adult tree productivity was negatively impacted during fire years, tree growth during years between fire events was resilient such that growth did not differ significantly among fire-return intervals. Our study shows that the longleaf pine population as a whole is strongly regulated by fire and fire-return interval plays a key role in structuring this population.

Ford, C.R., and J.M. Vose. 2007. Tsuga Canadensis (L.) Carr. mortality will impact hydrologic processes in southern Appalachian forest ecosystems. Ecological Applications. 17(4): 1156-1167.

Abstract
(1) Eastern hemlock (Tsuga canadensis (L.) Carr.) is one of the principal riparian and cove canopy species in the southern Appalachian Mountains. Throughout its range, eastern hemlock is facing potential widespread mortality from the hemlock woolly adelgid (HWA). If HWA-induced eastern hemlock mortality alters hydrologic function, land managers will be challenged to develop management strategies that restore function or mitigate impacts. To estimate the impact that the loss of this forest species will have on the hydrologic budget, we quantified and modeled transpiration over a range of tree sizes and environmental conditions. We used heat dissipation probes, leaf-level gas-exchange measurements, allometric scaling, and time series modeling techniques to quantify wholetree and leaf-level transpiration (EL) of eastern hemlock. We monitored trees ranging from 9.5 to 67.5 cm in diameter along a riparian corridor in western North Carolina, USA during 2004 and 2005. (2) Maximum rates of daily tree water use varied by diameter and height, with large trees transpiring a maximum of 178v186 kg H2O*tree-1*d-1. Values of EL could be predicted from current and lagged environmental variables. We forecasted eastern hemlock EL for inventoried stands and estimated a mean annual transpiration rate of 63.3 mm/yr for the hemlock component, with 50% being transpired in the winter and spring. In typical southern Appalachian stands, eastern hemlock mortality would thus reduce annual stand-level transpiration by ~10% and reduce winter and spring stand-level transpiration by ~30%. (3) Eastern hemlock in the southern Appalachians has two distinct ecohydrological roles: an evergreen tree that maintains year-round transpiration rates and a riparian tree that has high transpiration rates in the spring. No other native evergreen in the southern Appalachians will likely fill the ecohydrological role of eastern hemlock if widespread mortality occurs. With the loss of this species, we predict persistent increases in discharge, decreases in the diurnal amplitude of streamflow, and increases in the width of the variable source area.

Ford, C.R., Elliott, K.J., Clinton, B.D., Kloeppel, B.D., Vose, J.M., 2012. Forest dynamics following eastern hemlock mortality in the southern Appalachians. Oikos 121:4, April 2012, p. 523-536, doi: 10.1111/j.1600-0706.2011.19622.x, Nordic Society Oikos

Abstract
Understanding changes in community composition caused by invasive species is critical for predicting effects on ecosystem function, particularly when the invasive threatens a foundation species. Here we focus on dynamics of forest structure, composition and microclimate, and how these interact in southern Appalachian riparian forests following invasion by hemlock woolly adelgid, HWA, Adelges tsugae. We measured and quantified changes in microclimate; canopy mortality; canopy and shrub growth; understory species composition; and the cover and diversity in riparian forests dominated by eastern hemlock Tsuga canadensis over a period of seven years. Treatments manipulated hemlock mortality either through invasion (HWA infested stands) or girdling (GDL) hemlock trees. Mortality was rapid, with 50% hemlock tree mortality occurring after six years of invasion, in contrast to more than 50% mortality in two years following girdling. Although 50% of hemlock trees were still alive five years after infestation, leaf area lost was similar to that of girdled trees. As such, overall responses over time (changes in light transmittance, growth, soil moisture) were identical to girdled stands with 100% mortality. Our results showed different growth responses of the canopy species, shrubs and ground layer, with the latter being substantially influenced by presence of the evergreen shrub, rhododendron Rhododendron maximum. Although ground layer richness in the infested and girdled stands increased by threefold, they did not approach levels recorded in hardwood forests without rhododendron. Increased growth of co-occurring canopy trees occurred in the first few years following hemlock decline, with similar responses in both treatments. In contrast, growth of rhododendron continued to increase over time. By the end of the study it had a 2.6-fold higher growth rate than expected, likely taking advantage of increased light available during leaf-off periods of the deciduous species. Increased growth and dominance of rhododendron may be a major determinant of future responses in southern Appalachian ecosystems; however, our results suggest hemlock will be replaced by a mix of Acer, Betula, Fagus and Quercus canopy genera where establishment is not limited by rhododendron.

Ford, C.R., Hubbard, R. M., and Vose, J.M. 2011. Quantifying structural and physiological controls on canopy transpiration of planted pine and hardwood stands in the southern Appalachians. Ecohydrology 4(2):183-195.

Abstract
Recent studies have shown that planted pine stands exhibit higher evapotranspiration (ET) and are more sensitive to climatic conditions compared with hardwood stands. Whether this is due to management and stand effects, biological effects or their interaction is poorly understood. We estimated growing season canopy- and sap flux scaled leaf-level transpiration (Ec and EL) in five major overstory species over 3 years. Four hardwood species, Liriodendron tulipifera, Carya spp., Quercus rubra and Quercus prinus, were measured in an unmanaged watershed. Pinus strobus was measured in an adjacent planted pine watershed. We hypothesized that (1) species would differ in EL and stomatal conductance (GS), and their relationship with vapour pressure deficit (D); and (2) differences in growing season ET between the stands would result primarily from the differences in interception (Ei). Growing season ET in the planted pine stand exceeded hardwood ET by twofold during all 3 years. Transpiration and Ei contributed similarly to the ET difference, suggesting that physiological differences were equally as important as structural factors to the overall difference in ET. Among species, mean EL and GS differed significantly, as did their relationship with D. EL and GS of oaks and hickories were least responsive to changing D, while L. tulipifera and P. strobus were most responsive. This species-level understanding of variation in EL and GS and their interactions with climatic driving variables has important implications for predicting watershed-level responses to stand management, species invasion and loss, and climate variability.

Ford, C.R., J.M. Vose, M. Daley, and N. Phillips. 2007. Use of water by eastern hemlock: implications for systemic insecticide application. Arboriculture & Urban Forestry. 33(6): 421-427.

Abstract
The hemlock woolly adelgid (HWA; Adelges tsugae Annand) is causing widespread decline and mortality of eastern hemlock (Tsuga canadensis (L.) Carr.) throughout most of the range of eastern hemlock. Stem injection of insecticide is widely used as a chemical control measure, but the effectiveness of this method depends on the hydraulic characteristics of individual trees. We present data quantifying the distribution of water flux within the stems and the seasonal variability of daily water use of eastern hemlock trees growing in New England, U.S. and the southern Appalachians.

Ford, C.R., N. Wurzburger, R.L. Hendrick, and R.O. Teskey. 2007. Soil DIC uptake and fixation in Pinus taeda seedlings and its C contribution to plant tissue and ectomycorrhizal fungi. Tree Physiology. 27: 375-383.

Abstract
Plants can acquire carbon from sources other than atmospheric carbon dioxide (CO2), including soil-dissolved inorganic carbon (DIC). Although the net flux of CO2 is out of the root, soil DIC can be taken up by the root, transported within the plant, and fixed either photosynthetically or anaplerotically by plant tissues. We tested the ability of Pinus taeda L. seedlings exposed to 13C-labeled soil DIC and two NH+4 availability regimes to take up and fix soil DIC. We also measured the concentration and distribution of the fixed soil DIC within the plant and mycrorrhizal tissues, and quantified the contribution of soil DIC to whole-plant carbon (C) gain. Seedlings exposed to labeled DIC were significantly enriched in 13C compared with seedlings exposed to unlabeled DIC (6.7 versus -31.7%). Fixed soil DIC was almost evenly distributed between above- and belowground biomass (55 and 45%, respectively), but was unevenly distributed among tissues. Aboveground stem tissue contained 65% of the fixed soil DIC but represented only 27% of the aboveground biomass, suggesting either corticular photosynthesis or preferential stem allocation. Belowground, soil DIC had the greatest effect (measured as 13C enrichment) on the C pool of rapidly growing nonmycorrhizal roots. Soil DIC contributed ~0.8% to whole-plant C gain, and ~1.6% to belowground C gain. We observed a slight but nonsignificant increase in both relative C gain and the contribution of soil DIC to C gain in NH+4-fertilized seedlings. Increased NH+4 availability significantly altered the distribution of fixed soil DIC among tissue types and increased the amount of fixed soil DIC in ectomycorrhizal roots by 130% compared with unfertilized seedlings. Increased NH+4 availability did not increase fixation of soil DIC in nonmycorrhizal roots, suggesting the NH+4 assimilation may be concentrated in ectomycorrhizal fungal tissues, reflecting greater anaplerotic demands. Soil DIC is likely to contribute only a small amount of C to forest trees, but it may be important in C fixation processes of specific tissues, such as newly formed stems and fine roots, and ectomycorrhizal roots assimilating NH+4.

Ford, C.R., R.J. Mitchell, and R.O. Teskey. 2008. Water table depth affects productivity, water use, and the reponse to nitrogen addition in a savanna system. Canadian Journal of Forest Research. 38: 2118-2127.

Abstract
We investigated annual aboveground net primary productivity (ANPP) and transpiration (E) of the dominant plant life forms, longleaf pine (Pinus palustris Mill.) trees and wiregrass (Aristida stricta Michx.), in a fire-maintained savanna. Experimental plots spanned a natural hydrologic gradient (xeric and mesic site types) mediated by soil moisture () and water table depth (WTD), and received additions of either 0 or 100 kg Nha–1year–1.

Ford, C.R., R.M. Hubbard, B.D. Kloeppel, and J.M. Vose. 2007. A comparison of sap flux-based evapotranspiration estimates with catchment-scale water balance. Agricultural and Forest Meteorology. 145: 176-185.

Abstract
Many researchers are using sap flux to estimate tree-level transpiration, and to scale to stand- and catchment-level transpiration; yet studies evaluating the comparability of sap flux-based estimates of transpiration (Et) with alternative methods for estimating Et at this spatial scale are rare. Our ability to accurately scale from the probe to the tree to the watershed has not yet been demonstrated, nor do we know the relative impact of the main sources of variability on our scaled estimates. Accounting for the variability in the radial distribution of sap flux within the sapwood, the variability of transpiration among trees and between plots within the catchment, and the variability in stand density, sapwood area, and leaf area are critical for making landscape inferences about transpiration. During 2004 and 2005, we continuously monitored 40 trees in three plots within a 13.5-ha gauged watershed comprising a 50-year-old eastern white pine plantation within the Coweeta Basin in western North Carolina, USA. We scaled sap flux-based estimates of stand transpiration (Et) and surface area-based estimates of stand interception (Ei) to the catchment and compared these with water balance estimates of evapotranspiration (E, precipitation minus runoff, P Ro). For both years, the sum of sap flux scaled Et and Ei were 14 and 7% lower that evapotranspiration estimated from P Ro. Our results show that a considerable amount of variation exists at each scaling step encountered; however, a simple scaling exercise revealed that omitting among plot variation affected the sap flux scaled Et estimate by 48%. Thus, the largest source of variability in scaling to the landscape was landscape variation in stand density and sapwood area.

Ford, Chelcy R., Stephanie H. Laseter, Wayne T. Swank, and James M. Vose. 2011. Can forest management be used to sustain water-based ecosystem services in the face of climate change? Ecological Applications 21:2049-2067.

Abstract
Forested watersheds, an important provider of ecosystems services related to water supply, can have their structure, function, and resulting streamflow substantially altered by land use and land cover. Using a retrospective analysis and synthesis of long-term climate and streamflow data (75 years) from six watersheds differing in management histories we explored whether streamflow responded differently to variation in annual temperature and extreme precipitation than unmanaged watersheds. We show significant increases in temperature and the frequency of extreme wet and dry years since the 1980s. Response models explained almost all streamflow variability (adjusted R2 > 0.99). In all cases, changing land use altered streamflow. Observed watershed responses differed significantly in wet and dry extreme years in all but a stand managed as a coppice forest. Converting deciduous stands to pine altered the streamflow response to extreme annual precipitation the most; the apparent frequency of observed extreme wet years decreased on average by sevenfold. This increased soil water storage may reduce flood risk in wet years, but create conditions that could exacerbate drought. Forest management can potentially mitigate extreme annual precipitation associated with climate change; however, offsetting effects suggest the need for spatially explicit analyses of risk and vulnerability.

Ford, W.M., M.A. Menzel, D.W. McGill, J. Laerm, and T.S. McCay. 1999. Effects of a community restoration fire on small mammals and herpetofauna in the southern Appalachians. Forest Ecology and Management. 114: 233-243.

Abstract
As part of the Wine Spring Creek ecosystem management project on the Nantahala National forest, North Carolina, we assessed effects of a community restoration fire on small mammals and herpetofauna in the upper slope pitch pine (Pinus rigida) stands, neighboring midslope oak (Quercus spp.) stands and rhododendron (Rhododendron maximum) dominated riparian areas during 1995 and 1996. Using drift-fence arrays with pitfalls and snap-trapping, we collected these small mammals: masked shrew (Sorex cinereus), smoky shrew (5. fumeus), water shrew (S. palustris), pygmy shrew (S. hoyi), northern short-tailed shrew (Blarina brevicaudd), deer mouse (Peromyscus maniculatus), white-footed mouse (P. leucopus), golden mouse (Ochrotomys nuttalli), southern red-backed vole (Clethrionomys gapperi), pine vole (Microtus pinetorum) and woodland jumping mouse (Napaeozapus insignis). Herpetofauna collected from drift-fence arrays and time-constrained searches included: eastern newt (Notophtalmus viridescens), seepage salamander (Desmognathus aeneus), mountain dusky salamander (D. ochrophaeus), Blue Ridge two-lined salamander (Eurycea wilderae), spring salamander (Gyrinophilus porphyriticus), Jordan's salamander (Plethodon jordani), wood frog (Rana sylvatica), five-lined skink (Eumeces fasciatus), eastern garter snake (Thamnophis sirtalis), and northern ringneck snake (Diadophis punctatus). Prior to the prescribed community restoration fire in the spring of 1995, there were no significant differences in small mammal or herpetofauna collections between burned and control areas. Post-treatment in 1995 and 1996, showed no significant differences among collections of most species between burned and control areas. Slope position accounted for more variation among the species of greatest abundance than did burning. Concern for the effects of prescribed fire as a management tool on small mammals and herpetofauna in the southern Appalachians seems unwarranted.

Ford, W.M., M.A. Menzel, T.S. McCay, and J. Laerm. 2001. Contiguous Allopatry Of The Masked Shrew And Southeastern Shrew In The Southern Appalachians: Segregations Along An Elevational And Habitat Gradient. The Journal of the Elisha Mitchell Scientific So

Abstract
Southeastern shrew (Sorex longirostris) and masked shrew (Sorex cinereus) distributions converge in the southern Appalachians. A 306,454-pitfall-trapnight survey in Alabama, Georgia, North Carloina, and South Carolina documented the presence of southeastern shrews in the Cumberland Plateau Ridge and Valley, Upper Piedmonts, and Blue Ridge physiographic provinces. Southeastern shrews occur at low elevations (mean = 524.9 m), primarily in xeric upland hardwood, mixed pine (Pinus spp.)-hardwood, and pine forests. Masked shrews only occur in the Blue Ridge at high elevations (mean = 1,069.6 m), primarily in mesic cove hardwood, northern hardwood, and montane streamside forests. Upper elevation limits of southeastern shrew and lower elevational limits of masked shrew show an inverse relation with latitude relative to shrew collections from farther north along the Appalachians. Southeastern shrews and masked shrews are allopatric in the southern Appalachians except in the Blue Ridge where the species exhibit contiguous allopatry, based on elevation and habitat associations.

Fraterrigo, J. M. and J. A. Rusak. 2008. Disturbance-driven changes in the variability of ecological patterns and processes. Ecology Letters 11:756-770

Abstract
Understanding how disturbance shapes the dynamics of ecological systems is of fundamental importance in ecology. One emerging approach to revealing and appreciating disturbance effects involves examining disturbance-driven changes in the variability of ecological responses. Variability is rarely employed as a response variable to assess the influence of disturbance, but recent studies indicate that it can be an extremely sensitive metric, capturing differences obscured by averaging and conveying important ecological information about underlying causal processes. In this paper, we present a conceptual model to understand and predict the effects of disturbance on variability. The model estimates qualitative changes in variability by considering disturbance extent, frequency and intensity, as well as ecosystem recovery, and thereby captures not only the immediate effects of disturbance but also those that arise over time due to the biotic response to an event. We evaluate how well the model performs by comparing predictions with empirical results from studies examining a wide variety of disturbances and ecosystems, and discuss factors that may modify or even confound predictions. We include a concise guide to characterizing and detecting changes in variability, highlighting the most common and easily applied methods and conclude by describing several future directions for research. By considering variability as a response to disturbance, we gain another metric of fundamental system behaviour, an improved ability to identify organizing features of ecosystems and a better understanding of the predictability of disturbance-driven change – all critical aspects of assessing ecosystem response to disturbance.

Fraterrigo, J. M., Ream, K., & Knoepp, J. D. (2018). Tree mortality from insect infestation enhances carbon stabilization in southern Appalachian forest soils. Journal of Geophysical Research: Biogeosciences, 123, 2121–2134. https://doi.org/10.1029/2018JG004431

Abstract
Forest insect and pathogen outbreaks may exacerbate anthropogenic climate change if they accelerate soil carbon loss to the atmosphere. We quantified soil respiration and carbon content for nearly a decade after girdling or natural infestation of hemlock (Tsuga canadensis L. Carr., a codominant species in southern Appalachian forests) by hemlock woolly adelgid (Adelges tsugae) to improve understanding of soil carbon response to disturbance from forest insect and pathogens. From 2005 to 2013, net soil respiration was similar among hemlock mortality (~50% basal area reduction) and reference hardwood plots, but both girdled and hemlock woolly adelgid-infested plots showed greater activities of ß-glucosidase (a cellulose-hydrolyzing extracellular enzyme), decreased O-horizon, and decreased fine root biomass. During this period, mineral soil carbon accumulated at a higher rate in hemlock mortality plots than in reference plots in both surface (0–10 cm) and subsurface (10–30 cm) soils, driven by increases in the mineral-associated fraction of the soil organic matter. In contrast, particulate organic matter (POM) carbon accrued slowly in surface soils and declined in the subsurface of girdled plots. d13C values of the POM fraction demonstrate increased microbial processing of surface soil organic matter over time, suggesting enhanced decomposition of organic matter in this pool. These findings indicate that hemlock mortality in this system has led to enhanced soil carbon stabilization through the transformation and translocation of carbon from detrital and POM pools to the mineral-associated organic matter pool. Accelerated responses in the girdled versus naturally infested treatments highlight limitations associated with using girdling to simulate natural mortality.

Fraterrigo, J.M., M.G. Turner, and S.M. Pearson. 2006. Interactions between past land use, life-history traits and understory spatial heterogeneity. In Landscape Ecology. 21: 777-790.

Abstract
Past land use has contributed to variability in the distribution of herbaceous species by reducing plant abundance and altering species¼ chances of recolonizing suitable habitat. Land use may also influence plant heterogeneity by changing environmental conditions within stands. We compared the variability of understory herb abundance in southern Appalachian forests with different land-use histories to examine how past land use influenced plant heterogeneity. The cover of eleven focal species or genera was estimated and mineral soil concentrations were determined during 2001 and 2002 in eight stands that were farmed, logged, or had no disturbance history (reference) in western North Carolina. Analysis of the coefficients of variation revealed that the abundance of understory plants was more heterogeneous in disturbed stands compared with reference stands. However, when nutrient availability differences were accounted for by detrending the plant cover data, understory variability within stands declined, and no differences between disturbed and reference stands could be distinguished. This finding suggests that nutrient availability has important effects on plant heterogeneity, which depend on past land use. Species dispersal, seed size, and phenology also explained variability in the spatial heterogeneity of plants, but generally only before soil nutrient differences were statistically controlled. In addition to demonstrating that past land use has longterm effects on plant heterogeneity, these results indicate that soil nutrients may play different roles in determining vegetation patterns in historically altered and unaltered forests.

Fraterrigo, J.M., M.G. Turner, and S.M. Pearson. 2006. Previous land use alters plant allocation and growth in forest herbs. Journal of Ecology. 94: 548-557.

Abstract
(1) Former human practices can persistently influence forest ecosystems, particularly by altering the distribution and abundance of vegetation. Previous research has focused on the role of colonization success in governing plant community patterns in abandoned forests, but few studies have explored how changes in the performance of adult plants may contribute to changes in plant populations. (2) We examined patterns of biomass allocation and growth of 12 herbaceous plant species in southern Appalachian forest stands that have developed after agricultural abandonment or logging at least 55 years ago, to determine whether plant performance varied with land-use history. Soil nutrient availability and canopy closure were also investigated. (3) Adult plant biomass allocation varied appreciably among stands with different histories. Herbs in farmed stands generally allocated the most to leaves and the least to stems, while reference stands showed the opposite pattern. Plants in previously farmed sites had the highest rate of growth, although we observed considerable interspecific variation in plant performance. Stem allocation and relative growth rate were positively correlated in reference stands, but not in farmed or logged stands. Similarly, the growth of plants was clearly associated with soil nutrient concentration in reference stands but not in farmed or logged stands. (4) Differences in understorey density and soil nutrient availability may account for the observed patterns. Total herbaceous cover was appreciably lower in farmed and logged stands (58% and 51%) than in reference stands (78%), and soil phosphorus was higher in farmed stands than in logged and reference stands. Thus, competition for light and nutrients may be lower in farmed and logged stands than in reference stands, despite there being no difference in canopy closure with land-use history. (5) Overall, these results suggest that land-use history may influence environmental variables in ways that can enhance the performance of some herbaceous species. However, not all species may respond similarly to these changes.

Fraterrigo, J.M., M.G. Turner, S.M. Pearson, and P. Dixon. 2005. Effects of past land use on spatial heterogeneity of soil nutrients in southern Appalachian forests. Ecological Monographs. 75(2): 215-230.

Abstract
We examined patterns of nutrient heterogeneity in the mineral soil (0v15 cm depth) of 13 southern Appalachian forest stands in western North Carolina .60 yr after abandonment from pasture or timber harvest to investigate the long-term effects of land use on the spatial distribution and supply of soil resources. We measured soil carbon (C), nitrogen (N), acid-extractable phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) concentrations and pools, and potential net N mineralization and nitrification rates to evaluate differences in mean values, variance at multiple scales, and fine-scale spatial structure. While comparisons of averaged values rarely indicated that historical land use had an enduring effect on mineral soil or N cycling, differences in variance and spatial structure suggested that former activities continue to influence nutrient distributions by altering their spatial heterogeneity. Patterns differed by element, but generally variance of soil C, N, and Ca decreased and variance of soil P, K, and Mg increased with intensive past land use. Changes in variance were most conspicuous and consistent locally (,28 m), but C, Ca, P, and Mg also exhibited appreciable differences in variance at coarser scales (.150 m). High variability in soil compaction resulted in some changes in scale-dependent patterns of nutrient pool variance compared with nutrient concentration variance. It also affected the variance of N cycling rates, such that mass-based rates varied less and area-based rates varied more in intensively used areas than in reference stands. Geostatistical analysis suggested that past land use homogenized the spatial structure of soil C, K, and P in former pastures. In contrast, logged stands had highly variable spatial patterning for Ca.These results suggest that land use has persistent, multi-decadal effects on the spatial heterogeneity of soil resources, which may not be detectable when values are averaged across sites. By interacting with patterns of variability in the plant and heterotrophic biota, differences in nutrient distribution and supply could alter the composition and diversity of forest ecosystems. Scale-dependent changes in nutrient heterogeneity could also complicate efforts to determine biogeochemical budgets and cycling rates.

Fraterrigo, J.M., Pearson, S.M., Turner, M.G. 2009. Joint effects of habitat configuration and temporal stochasticity on population dynamics. Landscape Ecology 24(7): 863-877.

Abstract
Habitat configuration and temporal stochasticity in the environment are recognized as important drivers of population structure, yet few studies have examined the combined influence of these factors. We developed a spatially explicit simulation model to investigate how stochasticity in survival and reproduction influenced population dynamics on landscapes that differed in habitat configuration. Landscapes ranged from completely contiguous to highly fragmented, and simulated populations varied in mean survival probability (0.2, 0.4, 0.8) and dispersal capacity (1, 3, or 5 cells). Overall, habitat configuration had a large effect on populations, accounting for [80% of the variation in population size when mean survival and dispersal capacity were held constant. Stochasticity in survival and reproduction were much less influential, accounting for\1–14% of the variation in population size, but exacerbated the negative effects of habitat fragmentation by increasing the number of local extinctions in isolated patches. Stochasticity interacted strongly with both mean survival probability and habitat configuration. For example, survival stochasticity reduced population size when survival probability was high and habitat was fragmented, but had little effect on population size under other conditions. Reproductive stochasticity reduced population size irrespective of mean survival and habitat configuration, but had the largest effect when survival probability was intermediate and habitat was well connected. Stochasticity also enhanced the variability of population size in most cases. Contrary to expectations, increasing dispersal capacity did not increase population persistence, because the probability of finding suitable habitat within the dispersal neighborhood declined more for the same level of dispersal capacity when fragmentation was high compared to when it was low. These findings suggest that greater environmental variability, as might arise due to climate change, is likely to compound population losses due to habitat fragmentation and may directly reduce population size if reproductive output is compromised. It may also increase variability in population size.

Fraterrigo, J.M., Pearson, S.M., Turner, M.G. 2009. The response of understory herbaceous plants to nitrogen fertilization in forests of different land-use history. Forest Ecology and Management, 257: 2182-2188.

Abstract
Forests growing on former agricultural land often have reduced frequencies of many native forest herbs compared with forests that were never cleared for agriculture. A leading explanation for this pattern is thatmany forest herbs are dispersal limited, but environmental conditionsmay also hinder colonization. We examined the response of six forest herb taxa (Arisaema triphyllum, Cimicifuga racemosa, Disporum lanuginosum, Osmorhiza spp., Polygonatum spp., and Prenanthes altissima) to nitrogen (N) fertilization in forests with and without an agricultural history to investigate how N availability affects plant performance. The study was conducted in the southern Appalachian Mountains in western North Carolina, USA. There was a significant interaction between land-use history and N treatment for several species. In A. triphyllum and Osmorhiza spp., N fertilization increased aboveground biomass or leaf area more in the post-agriculture site than in the reference site. However, in the reference site, N fertilization depressed aboveground biomass or leaf area in the same taxa, as well as in C. racemosa. The foliar N concentration of these three taxa was elevated in fertilized plots regardless of land-use history, and there was no indication that the light environment differed among plots. These results suggest that some plants growing in post-agricultural stands may be N limited, whereas undisturbed stands in this region appear to be approaching N saturation. Thus, environmental conditions, and particularly N availability, may be an obstacle to the restoration of forest herb communities.

Fraterrigo, J.M., T.C. Balser, and M.G. Turner. 2006. Microbial community variation and its relationship with nitrogen mineralization in historically altered forests. Ecology. 87(3): 570-579.

Abstract
Past land use can impart soil legacies that have important implications for ecosystem function. Although these legacies have been linked with microbially mediated processes, little is know about the long-term influence of land use on soil microbial communities themselves. We examined whether historical land use affected soil microbial community composition (lipid profiles) and whether community composition was related to potential net nitrogen (N) mineralization rates in southern Appalachian (USA) forest stands abandoned from agriculture or logging and reforested > 50 yr ago. Microbial community composition was determined by a hybrid procedure of phospholipid fatty acid (PLFA) and fatty acid methyl ester (FAME) analysis. We found that community composition varied significantly with past land use. Communities in formerly farmed stands had a higher relative abundance of markers for gram-negative bacteria and a lower abundance of markers for fungi compared with previously logged and reference (i.e., no disturbance history) stands. Potential net N mineralization rates were negatively correlated with fungal and gram-negative bacterial markers in both farmed and reference stands, and fungal abundance and soil bulk density effectively predicted mineralization rates in all stands. Our results indicate that the alteration of microbial communities by historical land use may influence the ecosystem processes they mediate. This is in contrast to typical expectations about microbial community resilience to change. Here, the decrease in fungal abundance observed from disturbance appeared to result in decreased nitrogen mineralization over the long term.

Fraterrigo, J.M., Wagner, S. and Warren, R.J. II. 2014. Local-scale biotic interactions embedded in macroscale climate drivers suggest Eltonian noise hypothesis distribution patterns for an invasive grass. Ecology Letters. 17:1447-1454.

Abstract
A hierarchical view of niche relations reconciles the scale-dependent effects of abiotic and biotic processes on species distribution patterns and underlies most current approaches to distribution modeling. A key prediction of this framework is that the effects of biotic interactions will be averaged out at macroscales – an idea termed the Eltonian noise hypothesis (ENH). We test this prediction by quantifying regional variation in local abiotic and biotic niche relations and assess the role of macroclimate in structuring biotic interactions, using a non-native invasive grass, Microstegium vimineum, in its introduced range. Consistent with hierarchical niche relations and the ENH, macroclimate structures local biotic interactions, while local abiotic relations are regionally conserved. Biotic interactions suppress M. vimineum in drier climates but have little effect in wetter climates. A similar approach could be used to identify the macroclimatic conditions under which biotic interactions affect the accuracy of local predictions of species distributions.

Fraterrigo, Jennifer M., Michael S. Strickland, Ashley D. Keiser, Mark A. Bradford. 2011. Nitrogen uptake and preference in a forest understory following invasion by an exotic grass. Oecologia. DOI:10.1007/s00442-011-2030-0

Abstract
Plant–soil interactions have been proposed as a causative mechanism explaining how invasive plant species impact ecosystem processes. We evaluate whether an invasive plant influences plant and soil-microbe acquisition of nitrogen to elucidate the mechanistic pathways by which invaders might alter N availability. Using a 15N tracer, we quantify diVerences in nitrogen uptake and allocation in communities with and without Microstegium vimineum, a shade-tolerant, C4 grass that is rapidly invading the understories of eastern US deciduous forests. We further investigate if plants or the microbial biomass exhibit preferences for certain nitrogen forms (glycine, nitrate, and ammonium) to gain insight into nitrogen partitioning in invaded communities. Understory native plants and M. vimineum took up similar amounts of added nitrogen but allocated it diVerently, with native plants allocating primarily to roots and M. vimineum allocating most nitrogen to shoots. Plant nitrogen uptake was higher in invaded communities due primarily to the increase in understory biomass when M. vimineum was present, but for the microbial biomass, nitrogen uptake did not vary with invasion status. This translated to a signiWcant reduction (P < 0.001) in the ratio of microbial biomass to plant biomass nitrogen uptake, which suggests that, although the demand for nitrogen has intensiWed, microbes continue to be eVective nitrogen competitors. The microbial biomass exhibited a strong preference for ammonium over glycine and nitrate, regardless of invasion status. By comparison, native plants showed no nitrogen preferences and M. vimineum preferred inorganic nitrogen species. We interpret our Wndings as evidence that invasion by M. vimineum leads to changes in the partitioning of nitrogen above and belowground in forest understories, and to decreases in the microbial biomass, but it does not aVect the outcome of plant–microbe–nitrogen interactions, possibly due to functional shifts in the microbial community as a result of invasion.

Freeman, M.C., and D.J. Stouder. 1989. Intraspecific interactions influence size specific depth distribution in Cottus bairdi. Environmental Biology of Fishes 24(3): 231-236.

Abstract
Depth selection by different sizes of mottled sculpin, Cottus bairdi, was tested in a southern Appalachian stream. Field observations indicated that, during one hour periods, both small and large individuals move within an area less than 0.50 m2. Individuals of both sizes, placed in field enclosures, preferred deep microhabitat. When large fish were placed in cages with small fish, small fish initially spent more time in slope and shallow microhabitats. Average interfish distances were not correlated with their absolute size differences, suggesting C. bairdi interactions may involve both predation and competition. In streams, size-related differences in microhabitat depth may result more from intraspecific interactions than from size-specific depth preferences.

Freeman, M.C., and G.D. Grossman. 1993. Effects of habitat availability on dispersion of a stream cyprinid. Environmental Biology of Fishes. 37: 121-130.

Abstract
We analyzed temporal changes in the dispersion of the rosyside dace, Clinostomus funduloides, (family Cyprinidae) in a headwater stream, to assess the role of habitat availability in promoting fish aggregation. The dace foraged alone and in groups of up to about 25 individuals, and dispersion varied significantly among monthly censuses conducted from May through December. In two of three study pools, dace aggregated during July, October and/or December, but spread out during other months, especially during September when dispersion did not differ significantly from random. Dispersion was not significantly correlated with the total amount of suitable habitat available to foraging dace, but during summer, corresponded to the availability of depositional areas adjacent to rapid currents. Foragers aggregated in eddies or depositional areas during high stream discharge in July, and shifted out of depositional areas when current velocities declined from July to September. During late autumn, however, aggregations formed independently of changes in habitat conditions, and dace dispersion did not vary significantly among months in a third pool. The study suggests that dace dispersion cannot be predicted from the overall availability of suitable habitat as estimated from point measurements of depth and velocity; both the occurrence of a specific habitat feature (i.e., eddies adjacent to high velocity currents) and seasonal differences in behavior more strongly influenced the spatial distribution of foragers.

Freeman, M.C., and G.D.Grossman. 1992. Group foraging by a stream minnow: sho als or aggregations? Animal Behaviour. 44: 393-403.

Abstract
The importance of social attraction in the formation of foraging groups was examined for a stream-dwelling cyprinid, the rosyside dace, Clinostomus funduloides. Dace arrivals and departures at natural foraging sites were monitored and tested for (1) tendency of dace to travel in groups, and (2) dependency of arrival and departure rates on group size. Dace usually entered and departed foraging sites independently of each other. Group size usually affected neither arrival rate nor departure probability. Thus, attraction among dace appeared weak; foraging groups most often resulted from dace aggregating in preferred foraging sites. The strongest evidence of social attraction was during autumn, when dace departure probability often decreased with increasing group size, possibly in response to increased threat of predation by a seasonally occurring predator. Dacealso rarely avoided conspecifics, except when an aggressive individual defended a foraging site. Otherwise, there was litle evidence of exploitative competition among dace for drifting prey or of foraging benefits in groups, because group size usually did not affect individual feeding rates. These results suggest that the benefits of group foraging demonstrated under laboratory conditions in other studies may not always apply to field conditions.

Freeman, M.C., G.D. Grossman. 1992. A field test for competitive interactions among foraging stream fishes. Copeia 3: 898-902.

Abstract
We tested for competitive interactions among midwater stream fishes inhabiting small southern Appalachian streams. We directly observed fish foraging activity by snorkeling, and tested for significant differences in arrival, departure and feeding rates for the rosyside dace Clinostomus funduloides foraging in single-species groups compared to multi-species groups with the same numbers of dace. Observations lasted for 25-40 min and were made from August through November, 1988 and 1989, and in April and May 1989. Dace departure rates were significantly higher and feeding rates were significantly lower in foraging groups when a rainbow trout Oncorhynchus mkiss was present (9 observations); dace arrival rates to foraging groups were not affected by presence of a trout. In contrast, presence of other species of cyprinids (Luxilus coccogenis, Semotilus atromaculatus, Notropis leuciodus) did not significantly affect dace arrival or departure rates to foraging groups (6 observations). We observed only infrequent aggressive interactions between dace and trout or between dace and other cyprinids. Our results suggested that trout, but not co-occurring cyprinids, lowered the value of a foraging site for dace, most likely by exploitative competition for drifting prey. The approach of examining foraging group dynamics in relation to species composition provided a method of directly testing for significant interspecific interactions in the field.

Freeman, M.C., M.K. Crawford, J.C. Barrett, D.E. Facey, M.G. Flood, J. Hill, D.J. Stouder, and G.D. Grossman. 1988. Fish assemblage stability in a Southern Appalachian stream. Canadian Journal of Fisheries and Aquatic Sciences 45: 1949-1958.

Abstract
Fish populations were monitored at three sites in a southern Appalachian stream for 40 months. At two sites relative species abundances and production were persistent due to low variation in abundance of the two numerically dominant fishes, mottled sculpins (Cottus bairdi) and longnose dace (Rhinichthys cataractae). Less abundant residents, rosyside dace (Clinostomus funduloides), rainbow trout (Salmo gairdneri), and greenside darters (Etheostoma blennioides), displayed lower levels of persistence. Pronounced annual vairation in either young-of-the-year recruitment and/or subsequent year-class strength of four resident species possibly resulted from a severe drought during the third year of study. The three-species assemblage at a third site also was persistent as a result of relatively stable sculpin and longnose dace populations, whereas the rainbow trout population fluctuated among years. Significant intersite differences in relative year-class strength and in population structures of sculpins and longnose dace suggests that spatial variation in habitat characteristics affected assemblage dynamics and responses to environmental fluctuations.

Freeman, M.C., Pringle, C.M., Jackson, C.R. 2007. Hydrologic Connectivity and the Contribution of Stream Headwaters to Ecological integrity at Regional Scales. Journal of the American Water Resources Association 43(1): 5-14.

Abstract
Cumulatively, headwater streams contribute to maintaining hydrologic connectivity and ecosystem integrity at regional scales. Hydrologic connectivity is the water-mediated transport of matter, energy and organisms within or between elements of the hydrologic cycle. Headwater streams compose over two-thirds of total stream length in a typical river drainage and directly connect the upland and riparian landscape to the rest of the stream ecosystem. Altering headwater streams, e.g., by channelization, diversion through pipes, impoundment and burial, modifies fluxes between uplands and downstream river segments and eliminates distinctive habitats. The large-scale ecological effects of altering headwaters are amplified by land uses that alter runoff and nutrient loads to streams, and by widespread dam construction on larger rivers (which frequently leaves free-flowing upstream portions of river systems essential to sustaining aquatic biodiversity). We discuss three examples of large-scale consequences of cumulative headwater alteration. Downstream eutrophication and coastal hypoxia result, in part, from agricultural practices that alter headwaters and wetlands while increasing nutrient runoff. Extensive headwater alteration is also expected to lower secondary productivity of river systems by reducing stream-system length and trophic subsidies to downstream river segments, affecting aquatic communities and terrestrial wildlife that utilize aquatic resources. Reduced viability of freshwater biota may occur with cumulative headwater alteration, including for species that occupy a range of stream sizes but for which headwater streams diversify the network of interconnected populations or enhance survival for particular life stages. Developing a more predictive understanding of ecological patterns that may emerge on regional scales as a result of headwater alterations will require studies focused on components and pathways that connect headwaters to river, coastal and terrestrial ecosystems. Linkages between headwaters and downstream ecosystems cannot be discounted when addressing large-scale issues such as hypoxia in the Gulf of Mexico and global losses of biodiversity.

Frisch, John R., Peterson, James T., Cecala, Kristen K., Maerz, John C., Jackson, C. Rhett, Gragson, Ted L., and Pringle, Catherine M. 2016. Patch occupancy of stream fauna across a land cover gradient in the southern Appalachians, USA. Hydrobiologia. 773:163-175. doi:10.1007/s10750-016-2695-9.

Abstract
We modeled patch occupancy to examine factors that best predicted the prevalence of four functionally important focal stream consumers (Tallaperla spp., Cambarus spp., Pleurocera proxima, and Cottus bairdi) among 37 reaches within the Little Tennessee River basin of the southern Appalachian Mountains, USA. We compared 34 models of patch occupancy to examine the association of catchment and reach scale factors that varied as a result of converting forest to agricultural or urban land use. Occupancy of our taxa was linked to parameters reflecting both catchment and reach extent characteristics. At the catchment level, forest cover or its conversion to agriculture was a major determinant of occupancy for all four taxa. Patch occupancies of Tallaperla, Cambarus, and C. bairdi were positively, and Pleurocera negatively, correlated with forest cover. Secondarily at the reach level, local availability of large woody debris was important for Cambarus, availability of large cobble substrate was important for C. bairdi, and stream calcium concentration was important for P. proxima. Our results show the abundance of stream organisms was determined by the taxon-dependent interplay between catchment- and reach-level factors.

Frost, C. J., and M.D. Hunter. 2008. Herbivore-induced shifts in carbon and nitrogen allocation in red oak seedlings. New Phytologist. 178(4): 835-845.

Abstract
A dual-isotope, microcosm experiment was conducted with Quercus rubra (red oak) seedlings to test the hypothesis that foliar herbivory would increase belowground carbon allocation (BCA), carbon (C) rhizodeposition and nitrogen (N) uptake. Plant BCA links soil ecosystems to aboveground processes and can be affected by insect herbivores, though the extent of herbivore influences on BCA is not well understood in woody plants.

Frost, C.J., and M.D. Hunter. 2004. Insect canopy herbivory and frass deposition affect soil nutrient dynamics and export in oak mesocosms. Ecology. 85(12): 3335-3347.

Abstract
Increased nitrogen (N) mobilization and export from terrestrial forest ecosystems following canopy herbivory have been well documented, though the mechanism behind the loss is not clear. Because carbon + and N dynamics are closely linked, herbivore activity may also affect C distribution. We initiated a replicated mini-ecosystem experiment to test the hypothesis that insect frass (feces) influences soil C and N dynamics following insect defoliation. One hundred and sixty red oak (Quercus rubra) saplings were transplanted to seven-gallon (26.5-L) pots with soil and litter from the Coweeta Hydrologic Laboratory (CWT) (Otto, North Carolina, USA) and overwintered in experimental pot stands. During the 2002 growing season, trees were subjected to a 3 x 2 factorial experimental design with three damage groups (herbivore, mechanical, ¬¬undamaged¼¼) and two frass depositions (frass, no frass). Frass deposition increased soil total C, total N, and the soil NH4+ pool. Leachate NO3? export also increased following frass additions. We suggest that herbivore frass mobilizes sufficient C and N to affect soil pools and N export, though abiotic factors may influence the ultimate fate of the nutrients in frass. In addition, herbivory increased soil respiration and decreased total soil N relative to ¬¬undamaged¼¼ controls independent of frass deposition. While we discuss four possible mechanisms for this observation, we hypothesize that the increased soil respiration results from enhanced root-exudate C and subsequent microbial oxidation. This mechanism has implications for C sequestration and N retention in forest soils. In addition, the effects of mechanical damage consistently did not match those of real herbivory, suggesting that differential responses of Q. rubra to damage types also may affect soil nutrient dynamics. Our results demonstrate that the feeding activity of insect herbivores can have direct and indirect effects on the cycling of C and N within the season of defoliation.

Fry, B. 1991. Stable isotope diagrams of freshwater food webs. Ecology. 72(6): 2293-2297.

Abstract
Stable carbon and nitrogen isotopes are valuable tracers in ecological research (Rundel et al. 1988). One use of isotope measurements is to rapidly survey how organic matter is cycled in different ecosystems. For example, a few measurements of isotopic compositions of dissolved nutrients, aquatic plants, and animals establish a chemical outline of food web structure (Fry and Sherr 1984, Minagawa and Wada 1984). These racer results can be used to check conventional ideas about trophic structure in well-studied systems, and to test how food web structure varies in other systems where conventional visual studies of trophic relations are difficult or lacking (Rau 1980). A dual-isotope approach is often useful in these studies, for example, with nitrogen isotope measurements functioning as trophic level indicators, and carbon isotope measurements indicating which plants are important sources of nutrition for consumers (Peterson and Fry 1987).

Gao, X., O.A. Olapade, and L.G. Leff. 2005. Comparison of benthic bacterial community composition in nine streams. Aquatic Microbial Ecology. 40: 51-60.

Abstract
In this study, the abundance of major bacterial taxa (based on fluorescent in situ hybridization, FISH) and the structure of the bacterial community (based on denaturing gradient gel electrophoresis, DGGE) were determined in the benthos of 9 streams in the southeastern and midwestern United States and related to differences in environmental conditions. Taxa examined via FISH were Domain Bacteria, Domain Archaea, ?-, ?-, and ?-Proteobacteria, a portion of the Bacteroidetes (formerly Cytophaga-Flavobacterium-Bacteroides), and Gram-positive bacteria with high (actinobacteria) and low percent guanine+cytosine (GC) content. Of these taxa, generally the most abundant were the ?- and ?-Proteobacteria, which constituted on average 19.5 and 17.0% of the Domain Bacteria, respectively. Abundance of most taxa was significantly different among streams and sites within a stream. Based on canonical correspondence and correlation analyses, ?- and ?-Proteobacteria tended to be most abundant at sites with high dissolved organic carbon (DOC) and nitrate/nitrite concentrations and high benthic organic matter content. In contrast, ?-Proteobacteria were more abundant in environments with low DOC and nitrate/nitrite concentrations and low sediment organic carbon content. The other taxa did not exhibit clear correlations with the environmental variables measured. DGGE results revealed that the structure of the bacterial community differed among the streams examined, with limited differences in a given stream and much larger differences among streams. Overall, there were clear differences in community composition that in some cases correlated with differences in environmental conditions.

Gao, X., O.A. Olapade, M.W. Kershner, and L.G. Leff. 2004. Algal-bacterial co-variation in streams: A cross-stream comparison. Archiv fur Hydrobiologie. 159(2): 253-261.

Abstract
Algal-bacterial co-variation has been frequently observed in lentic and marine environments, but the existence of such relationships in lotic ecosystems is not well established. To examine possible co-variation, bacterial number and chlorophyll-a concentration in water and sediments of nine streams from different regions in the USA were examined. In the water, a strong relationship was found between chlorophyll concentration and bacterial abundance. There was not a significant linear relationship between the abundance of sediment bacteria and sediment or water chlorophyll concentration. The linear regression results obtained between bacterial numbers and chlorophyll concentration in water were generally similar to those reported in other studies on lentic and marine systems suggesting that factors that cause this co-variation may be similar.

Gardiner, N., Sutherland, A. B., Bixby, R. J., Scott, M. C., Meyer, J. L, Helfman, G. S., Benfield, E. F., Pringle, C. M., Bolstad, C. M., and D. N. Wear. 2008. Linking stream and landscape trajectories in the southern Appalachians. Environmental Monitoring and Assessment. 156(1-4):17-36.

Abstract
A proactive sampling strategy was designed and implemented in 2000 to document changes in streams whose catchment land uses were predicted to change over the next two decades due to increased building density. Diatoms, macroinvertebrates, fishes, suspended sediment, dissolved solids, and bed composition were measured at two reference sites and six sites where a socioeconomic model suggested new building construction would influence stream ecosystems in the future; we label these “hazard sites.” The six hazard sites were located in catchments with forested and agricultural land use histories. Diatoms were species-poor at reference sites, where riparian forest cover was significantly higher than all other sites. Cluster analysis, ishart’s distance function, non-metric multidimensional scaling, indicator species analysis, and t-tests show that macroinvertebrate assemblages, fish assemblages, in situ physical measures, and catchment land use and land cover were different between streams whose catchments were mostly forested, relative to those with agricultural land use histories and varying levels of current and predicted development.

Gaskin, J.W., J.F. Dowd, W.L. Nutter, and W.T. Swank. 1989. Vertical and lateral components of soil nutrient flux in a hillslope. Journal of Environmental Quality 18: 403-410.

Abstract
The vertical and lateral components of chemical flux during storm events were investigated in a Typic Hapludult to assess their importance in understanding the effects of atmospheric deposition on hillslope sites. Throughfall, stemflow, forest floor leachate, and soil solution from the BA, Bt, and BC horizons were sampled and analyzed for SO4,NO3-N, Cl, HCO3, H, K, Ca, Mg, and Na. Total lateral flow as a ratio of total vertical flow averaged 0.23 and 0.30 in the A and BA horizons, respectively, indicating lateral fluxes were an important path of nutrient movement in the surface horizons. Fluxes of all ions except HCO3, NO3-N, and H peaked in the forest floor leachate and the BA soil solution, then decreased with depth. Decreases of SO4 flux between the BA and BC horizons could not be explained by the lag of solute movement or by lateral solute losses, demonstrating the system was an effective S04 sink.

Gentry, J.B., E.P. Odum, M. Mason, V. Nabholz, S. Marshall, and J.T. McGinnis. 1968. Effect of altitude and forest manipulation on relative abundance of small mammals. Journal of Mammalogy 49(3): 539-541.

Abstract
Twenty-seven trapping lines were run over a 2,500-foot altitude gradient on disturbed and undisturbed watersheds at Coweeta to test the hypothesis that the frequency of small mammals increases with increasing altitude. The results confirmed the hypothesis. There were no significant differences between disturbed and undisturbed watersheds, but differences in the varieties of species were noted.

Georgian, T., and J.B. Wallace. 1983. Seasonal production dynamics in a guild of periphyton-grazing insects in a Southern Appalachian stream. Ecology 64(5): 1236-1248.

Abstract
Temporal partitioning has been found to be a predominant mode of ecological segregation among groups of systematically related stream insects. This concept was extended to a functionally similar but systematically diverse group of species. The life cycles and secondary production of six species of periphyton-grazing insects (scrapers) were studied in a fourth-order unshaded stream reach in the southern Appalachian Mountains. The production peaks of the six species occurred at separate points in the year, with very little overlap between species and were significantly more regularly spaced than would be expected by chance alone. The patterns of temporal organization observed in this group of species were linked with specialized life histories.

Georgian, T.J., and J.B. Wallace. 1981. A model of seston capture by net-spinning caddisflies. Oikos 36: 147-157.

Abstract
Six species of net-spinning caddisflies (Trichoptera) coexist in the headwater region of the Tallulah River, feeding on suspended organic matter (seston) captured by their nets. Data on net mesh sizes, microhabitat preferences, etc., were incorporated into a model of seston capture. Results indicate that these coexisting caddisflies do not reduce competition by partitioning available food by particle size. The model predicts annual seston capture far exceeding (1000 X) annual production by the six species. It is suggested that availability of high-quality food items (primarily drifting animals) is limiting to these filter-feeders, rather than overall seston supply.

Georgian, T.J., Jr. and J.B. Wallace. 1984. Seasonal production dynamics of six species of periphyton-grazing insects. BioScience. 34: 42-43.

Abstract
A condensation of Seasonal production dynamics in a guild of periphyton-grazing insects in a southern Appalachian stream.

Ghosh, S., A.E. Gelfand, K. Zhu, and J.S. Clark. 2012. The k-ZIG: flexible modeling for zero-inflated counts. Biometrics, on-line edition.

Abstract
Many applications involve count data from a process that yields an excess number of zeros. Zero-inflated count models, in particular, zero-inflated Poisson (ZIP) and zero-inflated negative binomial (ZINB) models, along with Poisson hurdle models, are commonly used to address this problem. However, these models struggle to explain extreme incidence of zeros (say more than 80%), especially to find important covariates. In fact, the ZIP may struggle even when the proportion is not extreme. To redress this problem we propose the class of k-ZIG models. These models allow more flexible modeling of both the zero-inflation and the nonzero counts, allowing interplay between these two components. We develop the properties of this new class of models, including reparameterization to a natural link function. The models are straightforwardly fitted within a Bayesian framework. The methodology is illustrated with simulated data examples as well as a forest seedling dataset obtained from the USDA Forest Service’s Forest Inventory and Analysis program.

Ghosh, S., Gelfand, A. and Clark, J.S. 2012. Inference for size demography from point pattern data using integral projection models. Journal of Agricultural, Biological and Environmental Statistics. (DOI: 10.1007/s13253-012-0121-y)

Abstract
Population dynamics with regard to evolution of traits has typically been studied using matrix projection models (MPMs). Recently, to work with continuous traits, in- tegral projection models (IPMs) have been proposed. Imitating the path with MPMs, IPMs are handled first with a fitting stage, then with a projection stage. Fitting these models has so far been done only with individual-level transition data. These data are used to estimate the demographic functions (survival, growth, fecundity) that comprise the kernel of the IPM specification. Then, the estimated kernel is iterated from an initial trait distribution to project steady state population behavior under this kernel. When trait distributions are observed over time, such an approach does not align projected distributions with these observed temporal benchmarks. The contribution here, focusing on size distributions, is to address this issue. Our concern is that the above approach introduces an inherent mismatch in scales. The re- distribution kernel in the IPM proposes a mechanistic description of population level redistribution. A kernel of the same functional form, fitted to data at the individual level, would provide a mechanistic model for individual-level processes. Resulting parameter estimates and the associated estimated kernel are at the wrong scale and do not allow population-level interpretation. Our approach views the observed size distribution at a given time as a point pattern over a bounded interval. We build a three-stage hierarchical model to infer about the dynamic intensities used to explain the observed point patterns. This model is driven by a latent deterministic IPM and we introduce uncertainty by having the operating IPM vary around this deterministic specification. Further uncertainty arises in the realiza- tion of the point pattern given the operating IPM. Fitted within a Bayesian framework, such modeling enables full inference about all features of the model. Such dynamic modeling, optimized by fitting to data observed over time, is better suited to projection. Exact Bayesian model fitting is very computationally challenging; we offer approx- imate strategies to facilitate computation. We illustrate with simulated data examples as well as well as a set of annual tree growth data from Duke Forest in North Carolina. A further example shows the benefit of our approach, in terms of projection, compared with the foregoing individual level fitting.

Gibson, C.A., R.E. Ratajczak Jr., and G.D. Grossman. 2004. Patch based predation in a southern Appalachian stream. Oikos. 106(1): 158-166.

Abstract
Streams are characterized by high degrees of patchiness that could influence the role of predators in these systems. Here we assess the impact of predatory benthic fishes on benthic macroinvertebrate density, biomass, and community structure at the patch scale in a fourth order stream in the southern Appalachians. We tested the role of predation in two different patch types: patches inhabited by adult mottled sculpin (Cottus bairdi) and random patches. We placed 30 basket pairs (one open to fish predation, and one from which fish predators were excluded) in the streambed at each patch type. We also tested for potential basket effects by setting up a basket control area. Although there was some evidence of basket artifacts on macroinvertebrate density in sculpin patches, these artifacts were not consistent and we do not feel that they affected our results because predators did not affect macroinvertebrate density. In random patches, predation did not significantly affect macroinvertebrate density or biomass. Predators significantly reduced macroinvertebrate biomass in sculpin patches but did not affect prey density. When the data-set was size-limited to exclude macroinvertebrates too large for consumption by sculpin, macroinvertebrate biomass did not differ significantly between exclusion and open baskets. This suggests that sculpin can reduce macroinvertebrate biomass through a combination of consumption and by predator-induced emigration of large macroinvertebrates into areas that are protected from sculpin. In addition, invertebrate predator biomass was higher in predator exclusion baskets in sculpin patches indicating that predation pressure Remained high in the exclusion baskets despite fish exclusion. These results illustrate the heterogeneity of streams and the effect of small-scale differences (e.g. location of predators+ territories) on local processes. Experiments that utilize these differences can provide insights into these stream processes.

Giladi, I. 2006. Choosing benefits or partners: a review of the evidence for the evolution of myroecochory. Oikos. 112: 481-492.

Abstract
Myrmecochory, or seed dispersal by ants, is a dispersal syndrome found among several thousand plant species occupying different ecosystems and geographical regions. Typically, ants benefit from consuming a lipid-rich appendage on the seed and in return provide seed dispersal service to the plant. Several hypotheses have been proposed to explain the selective advantage for plants resulting from myrmecochory, including directed dispersal, dispersal for distance and escape from seed predators. I contrast the evidence available in the literature for these hypotheses and distinguish the studies on the basis of ecosystem and plant growth forms. The predator-avoidance and the distance dispersal hypotheses were supported in most studies that addressed them, and the directed dispersal hypothesis was supported in about half of the studies that tested it. Multiple hypotheses were supported in most studies that tested more than one hypothesis, suggesting that the various selective advantages conferred from myrmecochory are seldom exclusive. I also review evidence for the hypothesis that plants have evolved adaptations both for selecting seed dispersers and for manipulating the behavior of those dispersers. Based on this evidence, I argue that focusing future research on the evolution of partner choice by myrmecochores and its effects on the overall plant fitness will be more fruitful than putting an emphasis on classifying the selective advantage to plants into distinct categories and test for their existence separately.

Gillespie, A.R., H.L. Allen, and J.M. Vose. 1994. Amount and vertical distribution of foliage of young loblolly pine trees as affected by canopy position and silvicultural treatment. Canadian Journal of Forest Research 24(7): 1337-1344.

Abstract
The objectives of this research were to quantify the effects of tree size and silvicultural treatment on the vertical distribution of foliage of individual trees of loblolly pine (Pinus taeda L.) and to estimate foliage quantity and distribution using easily measured tree data. Nonlinear and linear regression models were developed to test the effects of silvicultural treatment on individual branch foliage biomass and whole tree foliage biomass. Vertical distributions of foliage and branches were modelled using a Weibull probability density function. Analyses indicated that individual branch foliage biomass was positively related to branch size but negatively related to distance from the top of the tree. Fertilization with nitrogen and phosphorus, or thinning, increased the foliage biomass carried by a given sized branch. Silvicultural tretment effects on individual branches translated into whole-tree foliage biomass with thinning and fertilization increasing the crown size of individual trees. Though treatment affected crown size, the distribution of foliage (and branches) remained unaffected.

Gist, C.S., and D.A. Crossley Jr. 1975. Feeding rates of some cryptozoa as determined by isotopic half-life studies. Environmental Entomology 4: 625-631.

Abstract
Rates of ingestion were measured for nine groups of invertebrate cryptozoans, utilizing radioactive tracer turnover rate measurements. These groups were Diplopoda, Cryptostigmata, Pulmonata, Mesostigmata, Collembola, Orthoptera, Coleoptera, and two groups of Araneida. The radioisotopes 51344Cs and 5854Sr were considered as the metabolic analogs of potassium and calcium, respectively. Feeding rates were calculated as the ingestion necessary to maintain body pools of these elements. Values obtained were somewhat lower than results reported by others, possibly due to inflated estimates of assimilation for the radioisotopes.

Gist, C.S., and D.A. Crossley Jr. 1975. The litter arthropod community in a Southern Appalachian hardwood forest: numbers, biomass and mineral element content. American Midland Naturalist 93: 107-122.

Abstract
The biomass, numbers of individuals and mineral content of the arthropod fauna in the litter of a mixed hardwood forest were examined. The biomass values of the litter arthropods were generally higher than in other forests. Possible reasons for higher biomass values are discussed. Potassium and calcium standing crops are compared to those of a Liriodendron forest in Tennessee. With few exceptions the potassium values are comparable. However, there appear to be great differences in the calcium values.

Gist, C.S., and W.T. Swank. 1974. An optical planimeter for leaf area determination. American Midland Naturalist 92: 213-217.

Abstract
An optical planimeter for determining leaf area is presented. The system proposed is simple and easily used, compact and somewhat portable, accurate and species-independent with respect to estimates of leaf area. Calibration and tests have shown the system exhibits a linear response to changes in leaf area.

Golladay, S.W. 1997. Suspended articulate organic matter concentration and export in streams. In Webster, J.R. and J.L. Meyer (eds.), Stream organic matter budgets. Journal of the North American Benthological Society. 16: 122-131.

Abstract
This chapter is part of a multi-site analysis of organic matter dynamics in streams. Terrestrial and riparian vegetation was found to play an important role in regulating POM concentration and export, with higher values observed in forested streams and in lower gradient streams with extensive floodplains.

Golladay, S.W., and J.R. Webster. 1988. Effects of clear-cut logging on wood breakdown in Appalachian Mountain streams. The American Midland Naturalist 119(1): 143-155.

Abstract
Red oak sticks, approximately 10-cm long and in three size classes were placed in two second-order streams at Coweeta. Big Hurricane Branch drains a watershed logged in 1976 (WS7), while Hugh White Creek drains an uncut reference watershed (WS14). Sticks were collected at 6-month to 1-year intervals from September 1981 through November 1985. Breakdown rates were significantly different among size classes on both watersheds; smaller sticks lost mass faster than larger sticks. Breakdown rates of similar size sticks were significantly faster in the disturbed stream than in Hugh White Creek. Faster rates of wood breakdown in Big Hurricane Branch may be associated with higher stream NO3-N levels, greater stream channel instability and greater invertebrate abundance on sticks.

Golladay, S.W., J.R. Webster, and E.F. Benfield. 1983. Factors affecting food utilization by a leaf shredding aquatic insect: leaf species and conditioning time. Holarctic Ecology 6: 157-162.

Abstract
Gravimetric feeding studies were used to examine the feeding strategy of Pteronarcys proteus (Plecoptera) using unconditioned, 1-month conditioned, and 2-month conditioned deciduous leaves of four species. Assimilation efficiencies of Pteronarcys nymphs feeding on unconditioned and conditioned leaf material ranged from 13.4 to 21.9 percent AFDW of leaf material, indicating that Pteronarcys was able to digest and assimilate leaf material. Assimilation efficiences did not change as leaf material conditioned, which suggests that assimilation efficiency does not accurately reflect changes in detrital food quality. However, as leaves conditioned, the ingestion rate of Pteronarcys nymphs accelerated. Assimilation rates of Pteronarcys nymphs varied in a pattern similar to ingestion rates. This reflects the importance of ingestion rate in the feeding response of Pteronarcys.

Golladay, S.W., J.R. Webster, and E.F. Benfield. 1987. Changes in stream morphology and storm transport of seston following watershed disturbance. Journal of North American Benthological Society 6(1): 1-11.

Abstract
Particulate organic matter (seston) was sampled during baseflows and stormflows in streams draining an 8-year-old clearcut, a 25-year-old clearcut, and two reference watersheds. There were fewer debris dams and organic matter accumulations in disturbed streams. Baseflow seston concentrations varied seasonally, increasing during summer, but did not differ consistently between streams. In all streams, seston concentration increased with increasing discharge during storms, decreased during peak flows, and gradually declined as discharge returned to baseflow. Average seston concentrations during storms were generally highest in streams draining disturbed watersheds. Storm transport varied with season, storm intensity, and storm duration. Results show that baseflow seston concentrations in streams draining disturbed areas may return to normal levels within a few years following disturbances; however, concentrations during storms may remain elevated for many years.

Golladay, S.W., J.R. Webster, and E.F. Benfield. 1989. Changes in stream benthic organic matter following watershed disturbance. Holarctic Ecology 12: 96-105.

Abstract
Comparisons of organic matter inputs with standing stocks indicated that disturbed streams receive less material and process it faster than reference streams. Benthic organic matter was collected quarterly from streams draining a 9-yr-old clearcut, an 18-yr-old old-field, a 25-yr-old successional forest, and two reference watersheds at Coweeta. Samples were separated into large benthic organic matter (LBOM >1 mm) and fine benthic organic matter (FBOM <1 mm) and large (>5 cm diam.) and small (1-5 cm diam.) wood. Standing stocks of LBOM were significantly higher in streams draining reference watersheds and the successional forest than in either the recent clearcut or old-field. Reference sites exhibited LBOM peaks in late autumn and spring. No seasonal patterns were observed in disturbed streams. The stream draining the successional forest had significantly higher FBOM levels than the other sites. Standing stocks of large wood were significantly higher in the reference streams than in streams draining the old-field or successional forest. Small wood was significantly lower in the stream draining the old-field than at the other sites.

Golladay, S.W., J.R. Webster, E.F. Benfield, and W.T. Swank. 1992. Changes in stream stability following forest clearing as indicated by storm nutrient budgets: part 1 of 2. Archiv fur Hydrobiologie 90: 1-33.

Abstract
This study examined changes in stream stability following forest disturbance. The index of stability used was input/output nutrient budgets, constructed for disturbed and reference streams during storms. Thus, a frequently occurring natural phenomenon (storms) was used to evaluate the effects of a large scale disturbance (forest clearing). Nutrient budgets indicated that disturbed streams were less retentive of nitrogen and phosphorus than reference sites. Nitrogen loss averaged 57 mg/m2 streambed/storm from disturbed and 16 mg/m2 streambed/storm from reference sites. Phosphorus losses were 34 and 9 mg/m2 streambed/storm from disturbed and reference streams respectively. Nitrogen and phosphorus loss was largely accounted for by export of nutrients associated with organic particles. There were no differences in input/output budgets for calcium and potassium than reference sites. Changes in stream stability following forest clearing were attributable to changes in the linkage between streams and forest vegetation. Forest recovery is an autogenic process, determined by the rate of forest regrowth. Stream recovery is largely allogenic, dependent on the return of predisturbance patterns of organic inputs and processing rates which decreased the abundance of retention structures in streams. The net effect was a decrease in the ability of streams to resist the downstream transport of nutrients during storms.

Grace III, J.M., Clinton, B.D. 2007. Protecting Soil and Water in Forest Road Management. American Society of Agricultural and Biological Engineers, 50(5): 1579-1584

Abstract
The National Forest road system is the network that supports public recreation, which has become the primary use of the public lands. The pattern of use of National Forest roads for recreation has increased dramatically since the late 1940s and is expected to continue to increase beyond the rates observed today. However, research over the past 60 years clearly presents forest roads as a major source of sediment and soil erosion from forest watersheds. Threats to healthy forests have received increased attention in the past decade. In particular, roads, road management, and travel management will likely be critical to addressing the four threats to the health of the nation's forests and grasslands that were identified by USDA Forest Service. Road management is an important component in preserving and maintaining healthy forests throughout the nation. Sediment export from the existing forest road network is an issue of great concern in forest management. The objective of this article is to provide an overview of issues involved in managing the nation's public forest roads for the protection of soil and water. This article explores the benefit and efficacy of erosion mitigation, sediment control, and road BMPs in protecting soil and water. This article also suggests areas requiring additional research and development to satisfy the goals of protecting forest soil and water.

Gragson, T.L., and P.V. Bolstad. 2006. Land use legacies and the future of southern Appalachia. Society and Natural Resources. 19: 175-190.

Abstract
Southern Appalachian forests have apparently recovered from extractive land use practices during the 19th and 20th centuries, yet the legacy of this use endures in terrestrial and aquatic systems of the region. The focus on shallow time or the telling of stories about the past circumscribes the ability to anticipate the most likely outcomes of the trajectory of change forecast for the Southeast as the ¬¬Old South¼¼ continues its transformation into the ¬¬New South.¼¼ We review land use research of the Coweeta Long Term Ecological Research (LTER) project that addresses the nature and extent of past and present human land use, how land use has affected the structure and function of terrestrial and aquatic communities, and the forces guiding the anticipated trajectory of change. Unlike development in the western or northeastern regions of the United States, the southeastern region has few practical, political, or geographical boundaries to the urban sprawl that is now developing.

Gragson, T.L., Bolstad, P.V. 2007. A Local Analysis of Early-Eighteenth-Century Cherokee Settlement. Social Science History 31(3): 435-468

Abstract
Results of an original analysis of Cherokee town placement and population c. 1721 are presented. Period and contemporary information were analyzed using local statistics to produce multivalued, mappable characterizations of the intensity of the processes of town placement and population. The analysis focuses on the scale and the space in which these processes took place among the Cherokee in order to open the way for examining the legacy of human-induced environmental change in southern Appalachia.

Gragson, Ted L., and M. Grove. 2006. Social science in the context of the long term ecological research program. Society and Natural Resources. 19: 93-100.

Abstract
This special issue of Society and Natural Resources brings the results of long-term ecological research with an explicit social dimension to the attention of the social scientific research community. Contributions are from the Baltimore Ecosystem Study LTER, the Central Arizona-Phoenix LTER, the Coweeta LTER and the Northern Temperate Lakes LTER. The range of practice represented at these four sites serves to identify commonalities and differences in the results as well as the experience of integrative research. The objective of this special issue is to extend a call to social scientists of all kinds to engage with the LTER program in long-term research and synthesis to help answer the urgent and intriguing questions of our day.

Grantham, J.H., and M.A. Velbel. 1988. The influence of climate and topography on rock-fragment abundance in modern fluvial sands of the southern Blue Ridge Mountains, North Carolina. Journal of Sedimentary Petrology 58(2): 219-227.

Abstract
Chemical weathering influences the detrital composition of sand-size sediment derived from source areas subject to different amounts of precipitation in the Coweeta Basin. Of the grain types studied, rock fragments are most sensitive to chemical degradation; therefore, their abundance is the best indicator of cumulative weathering effects. In the Coweeta Basin, the intensity of chemical weathering is directly related to the climate via effective precipitation, whereas the duration of chemical weathering is inversely related to the topographic slope of the watershed. Therefore, soils in watersheds with low-relief and high discharge per unit area experience the most extensive chemical weathering, and sediments derived from these watersheds contain the lowest percentage of rock fragments.

Graves, R. A., S. M. Pearson, and M. G. Turner. (2017). Landscape dynamics of floral resources affect the supply of a biodiversity-dependent cultural ecosystem service. Landscape Ecology 32:415-428.

Abstract
Context Cultural ecosystem services, many of which depend on biodiversity, are recognized as important but seldom quantified biophysically across landscapes. Furthermore, many ecosystem service models are static, and the supply of cultural ecosystem services may be misrepresented if seasonal shifts in biotic communities are ignored. Objectives We modeled landscape dynamics of wildflower blooms in a temperate montane landscape to determine (1) how floral resources (wildflower species richness, abundance, timing, and presence of charismatic species) changed over the growing season, (2) how projected wildflower viewing hotspots varied over space and time, and (3) how spatial shifts in floral resources affected potential public access to wildflower viewing. Methods Data were collected at 63 sites across a rural-to-urban gradient in the Southern Appalachian Mountains (USA). Generalized linear models were used to identify factors affecting floral resources at two temporal scales. Floral resources were projected across the landscape and hotspots of wildflower viewing were quantified using overlay analysis. Results Floral resources were affected by topoedaphic conditions, climate, and surrounding building density and changed seasonally. Seasonal models revealed locational shifts in ecosystem service hotspots, which changed the proportion of hotspots accessible to the public and identified wildflower-viewing opportunities unnoticed by static models. Conclusion Relationships between landscape gradients, biodiversity, and ecosystem service supply varied seasonally, and our models identified cultural ecosystem service hotspots otherwise obscured by simple proxies. Landscape models of biodiversity-based cultural ecosystem services should include seasonal dynamics of biotic communities to avoid under- or over-emphasizing the importance of particular locations in ecosystem service assessments.

Graves, R. A., S. M. Pearson, and M. G. Turner. 2016. Landscape patterns of bioenergy in a changing climate: implications for crop allocation and land-use competition. Ecological Applications 26:515-529. (http://dx.doi.org/10.1890/15-0545.1)

Abstract
Rural landscapes face changing climate, shifting development pressure, and loss of agricultural land. Perennial bioenergy crops grown on existing agricultural land may provide an opportunity to conserve rural landscapes while addressing increased demand for biofuels. However, increased bioenergy production and changing land use raise concerns for tradeoffs within the food-energy-environment trilemma. Heterogeneity of climate, soils, and land use complicate assessment of bioenergy potential in complex landscapes creating challenges to evaluating future tradeoffs. The hypothesis addressed herein is that perennial bioenergy production can provide an opportunity to avoid agricultural land conversion to development. Using a process-based crop model, we assessed potential bioenergy crop growth through 2100 in a southern Appalachian Mountain region and asked: (1) how mean annual yield differed among three crops (switchgrass, giant miscanthus, and hybrid poplar) under current climate and climate change scenarios resulting from moderate and very-high greenhouse gas emissions; (2) how maximum landscape yield, spatial allocation of crops, and bioenergy hotspots (areas with highest potential yield) varied among climate scenarios; and (3) how bioenergy hotspots overlapped with current crop production or lands with high development pressure. Under both climate change scenarios, mean annual yield of perennial grasses decreased (-4% to -39%), but yield of hybrid poplar increased (+8% to +20%) which suggests that a switch to woody crops would maximize bioenergy crop production. In total, maximum landscape yield increased by up to 90,000 Mg yr-1 (6%) in the 21st Century due to increased poplar production. Bioenergy hotspots (>18 Mg ha-1yr-1) consistently overlapped with high suburban/exurban development likelihood and existing row crop production. If bioenergy production is constrained to marginal (non-crop) lands, landscape yield decreased by 27%. The removal of lands with high development probability from crop production resulted in losses of up to 670,000 Mg yr-1 (40%). This study demonstrated that tradeoffs among bioenergy production, crop production, and exurban expansion in a mountainous changing rural landscape vary spatially with climate change over time. If markets develop, bioenergy crops could potentially counter losses of agricultural land to development.

Graves, R.A., Pearson, S.M. & Turner, M.G. (2017), Landscape dynamics of floral resources affect the supply of a biodiversity-dependent cultural ecosystem service, Landscape Ecol 32: 415. doi:10.1007/s10980-016-0452-0

Abstract
Context - Cultural ecosystem services, many of which depend on biodiversity, are recognized as important but seldom quantified biophysically across landscapes. Furthermore, many ecosystem service models are static, and the supply of cultural ecosystem services may be misrepresented if seasonal shifts in biotic communities are ignored. Objectives - We modeled landscape dynamics of wildflower blooms in a temperate montane landscape to determine (1) how floral resources (wildflower species richness, abundance, timing, and presence of charismatic species) changed over the growing season, (2) how projectedwildflower viewing hotspots varied over space and time, and (3) how spatial shifts in floral resources affected potential public access to wildflower viewing. Methods - Data were collected at 63 sites across a rural-to-urban gradient in the Southern Appalachian Mountains (USA). Generalized linear models were used to identify factors affecting floral resources at two temporal scales. Floral resources were projected across the landscape and hotspots of wildflower viewing were quantified using overlay analysis. Results - Floral resources were affected by topoedaphic conditions, climate, and surrounding building density and changed seasonally. Seasonal models revealed locational shifts in ecosystem service hotspots, which changed the proportion of hotspots accessible to the public and identified wildflowerviewing opportunities unnoticed by static models. Conclusion - Relationships between landscape gradients, biodiversity, and ecosystem service supply varied seasonally, and our models identified cultural ecosystem service hotspots otherwise obscured by simple proxies. Landscape models of biodiversity based cultural ecosystem services should include seasonal dynamics of biotic communities to avoid under- or over-emphasizing the importance of particular locations in ecosystem service assessments.

Graves, R.A., S.M. Pearson, and M.G. Turner. 2017. Species richness alone does not predict cultural ecosystem service value. Proceedings of the National Academy of Sciences of the United States of America. (DOI:10.1073/pnas.1701370114)

Abstract
Sustaining biodiversity and ecosystem services are common conservation goals. However, understanding relationships between biodiversity and cultural ecosystem services (CES) and determining the best indicators to represent CES remain crucial challenges. We combined ecological and social data to compare CES value of wildflower communities based on observed species richness versus revealed social preferences. Using a discrete-choice experiment with images of wildflower communities, we analyzed which aspects of biodiversity were associated with the aesthetic preferences of forest visitors. Although commonly used to indicate biodiversity-based CES, species richness did not predict aesthetic preference. This study suggests that successful management of CES requires understanding stakeholders’ preferences to determine conservation priorities.

Greene, G.E. 1950. Land use and trout streams. Journal of Soil and Water Conservation 5: 125-126.

Abstract
Maximum stream temperatures rose appreciably when a forested watershed at Coweeta was converted to a mountain farm. Because absence of shade can increase stream temperatures, riparian vegetation should be carefully manipulated to maintain optimum temperatures for growth and development of trout and aquatic organisms.

Greenland, D., and L.W. Swift Jr. 1991. Climate variability and ecosystem response: opportunities for the LTER network. Bulletin of the Ecological Society of America 72(2): 118-126.

Abstract
Unusual ecosystem responses are frequently driven by meteorological events. The frequency and magnitude of these events and responses can be characterized through Long-Term Ecological Research (LTER). The LTER Climate Committee identifies four issues to be considered in future investigations: (1) the need to clarify terms and definitions used in discussing climate variability, (2) the importance of recognizing the various time and space scales of climate variability and ecosystem response, (3) the need to expand data beyond dependence on traditional summaries of temperature and precipitation, and (4) the value of insights gained from examining similarities and dissimilarities among climate episodes and ecosystem responses across LTER sites.

Greenwood, J.L., Rosemond, A.D. 2005. Periphyton response to long-term nutrient enrichment in a shaded headwater stream. Canadian Journal of Fish and Aquatic Science, 62:2033-2045.

Abstract
We maintained elevated but moderate concentrations of nitrogen and phosphorus continuously for 2 years in a heavily shaded headwater stream and compared effects on stream periphyton with a reference stream. Both streams were sampled for 1 year before treatment. Some measures of periphyton biomass (ash-free dry mass and chlorophyll a) responded positively to enrichment. Increased chlorophyll a was likely a result of higher chlorophyll per cell, as total algal biovolume did not change with enrichment. These differences were greatest during high-light months (November– May), when cellular growth rates (a proxy for production) were also highest with enrichment. Algal assemblages were dominated by diatoms and remained similar between the treatment and reference streams throughout the enrichment period. Although nutrients stimulated algal growth rates, the long-term effects of nutrient addition on periphyton biomass were small in magnitude compared with other published values and were potentially suppressed by light availability and invertebrate consumption. These and other factors may have also been important in limiting the algal species pool and thus a taxonomic response to enrichment. Our results indicate that in headwater streams with intact tree canopies, chronic nutrient enrichment at moderate concentrations may have little detectable effect on benthic algal composition or periphyton biomass. Although nutrients stimulated algal growth rates, the long-term effects of nutrient addition on periphyton biomass were small in magnitude compared with other published values and were potentially suppressed by light availability and invertebrate consumption. These and other factors may have also been important in limiting the algal species pool and thus a taxonomic response to enrichment. Our results indicate that in headwater streams with intact tree canopies, chronic nutrient enrichment at moderate concentrations may have little detectable effect on benthic algal composition or periphyton biomass.

Greenwood, J.L., Rosemond, A.D., Wallace, J.B., Cross, W.F., Weyers, H.S. 2007. Nutrients stimulate leaf breakdown rates and detritivore biomass: bottom-up effects via heterotrophic pathways. Oecologia, 151:637-649.

Abstract
Most nutrient enrichment studies in aquatic systems have focused on autotrophic food webs in systems where primary producers dominate the resource base. We tested the heterotrophic response to longterm nutrient enrichment in a forested, headwater stream. Our study design consisted of 2 years of pretreatment data in a reference and treatment stream and 2 years of continuous nitrogen (N) + phosphorus addition to the treatment stream. Studies were conducted with two leaf species that diVered in initial C:N, Rhododendron maximum (rhododendron) and Acer rubrum (red maple). We determined the eVects of nutrient addition on detrital resources (leaf breakdown rates, litter C:N and microbial activity) and tested whether nutrient enrichment aVected macroinvertebrate consumers via increased biomass. Leaf breakdown rates were ca. 1.5 and 3£ faster during the Wrst and second years of enrichment, respectively, in the treatment stream for both leaf types. Microbial respiration rates of both leaf types were 3£ higher with enrichment, and macroinvertebrate biomass associated with leaves increased ca. 2–3£ with enrichment. The mass of N in macroinvertebrate biomass relative to leaves tended to increase with enrichment up to 6£ for red maple and up to 44£ for rhododendron leaves. Lower quality (higher C:N) rhododendron leaves exhibited greater changes in leaf nutrient content and macroinvertebrate response to nutrient enrichment than red maple leaves, suggesting a unique response by diVerent leaf species to nutrient enrichment. Nutrient concentrations used in this study were moderate and equivalent to those in streams draining watersheds with altered land use. Thus, our results suggest that similarly moderate levels of enrichment may aVect detrital resource quality and subsequently lead to altered energy and nutrient Xow in detrital food webs.

Grossman, G. D., Sundin, G. and Ratajczak, R. E. 2016. Long-term persistence, density dependence and effects of climate change on rosyside dace (Cyprinidae). Freshwater Biology, 61:832–847. doi:10.1111/fwb.12741.

Abstract
1. We used long-term population data for rosyside dace (Clinostomus funduloides), a numerically dominant member of a stochastically organised fish assemblage, to evaluate the relative importance of density-dependent and density-independent processes to population persistence. 2. We also evaluated the potential impacts of global climate change (GCC) on this species and predicted how directional environmental changes will affect dace. 3. We sampled two 30 m permanent sites in spring and autumn in the Coweeta catchment for rosyside dace density using three-pass electrofishing between 1984 and 1995, and a single 100 m site from 1991 to 2003. 4. Habitat availability and flow variation data for this 20-year period demonstrated that two droughts (1985–1988 and 1999–2002) produced smaller wetted areas, lower mean, maximum and minimum flows, fewer high flow events and greater amounts of depositional substrata in the sites. 5. Droughts produced significant increases in abundance, and significant decreases in standard length and mass of rosyside dace. Increases in abundance were mainly due to increased survival/ immigration of young-of-the-year (YOY). 6. Model selection analysis using multiple single and multivariable models indicated that density dependence in various forms possessed substantial explanatory power with respect to long-term variation in the per-capita rate of increase (r) in all sites and seasons. Density-dependent effects on r were stronger in autumn than spring, whereas negative density-independent models (flow variation) had the greatest explanatory power in spring. 7. Results for growth data were similar to those for rosyside dace density and confirm density dependence likely through intraspecific competition for food or foraging sites leading to reduced growth at higher densities. 8. These data support the hypothesis that species may persist in stochastic animal assemblages via strong intraspecific density dependence. Greater flow variability or increased high flows produced by GCC may destabilise this population leading to reduced compensation and possibly eventual extinction.

Grossman, G.D. 1998. Notes from the Blackboard: Choosing the right graduate school and getting the job you've always wanted. Fisheries. 23(9): 16-17.

Abstract
The author gives advice for graduate students in the field of fisheries.

Grossman, G.D., and M.C. Freeman. 1987. Microhabitat use in a stream fish assemblage. The Journal of the Zoological Society of London 212: 151-176.

Abstract
We examined microhabitat use among fishes in a 37-m section of Coweeta Creek. Numerical abundances of species changed substantially during the 17-month study period. Microhabitat availability, however, did not change markedly. Analyses of microhabitat availability and fish microhabitat use show two main patterns of non-random microhabitat use. Clinostomus funduloides, Notropis coccogenis and Semotilus atromaculatus were significantly over-represented in deep areas with low velocities and depositional substrata. Campostoma oligolepis, Cottus bairdi, Etheostoma blennoides, Rhinichthys cataractae and Salmo gairdneri all occurred in intermediate to deep microhabitats with moderate to high velocities and erosional substrata. Five of seven species exhibited seasonal variation in microhabitat utilization, whereas six species displayed size-related variation in use. Species could be assigned to either a benthic or a water column guild. Species within a guild generally could not be differentiated statistically, whereas members of different guilds were readily separable. These patterns persisted despite changes in numerical abundances. There was no evidence of either exploitation or interference competition for microhabitat, consequently it is unlikely that spatial resources were limiting.

Grossman, G.D., and R.E. Ratajczak Jr. 1998. Long-term patterns of microhabitat use by fish in a southern Appalachian stream from 1983 to 1992: effects of hydrologic period, season and fish length. Ecology of Freshwater Fish. 7: 108-131.

Abstract
We quantified microhabitat use by members of a southern Appalachian stream fish assemblage over a ten-year period that included both floods and droughts. Our study site encompassed riffle, run and pool habitats. Previous research indicated that species belonged to either benthic or water-column microhabitat guilds. Most species exhibited non-random microhabitat use in all seasons, and benthic and water column species generally were over-represented in the deeper portions of the site. In addition, water column species generally were over represented in microhabitats with lover average velocities. The majority of seasonal shifts in microhabitat use were passive, whereas, most shifts associated with hydrologic periods appeared to be active responses to changing environmental conditions. Most species exhibited length-related shifts in microhabitat use, which were strongly affected by hydrologic period for four of ten species. Microhabitat use patterns of assemblage members appeared to be a consequence of species-specific responses to changing environmental conditions. The highly flexible patterns of microhabitat use exhibited by these species necessitate that decisions regarding their management be based on data covering a range of environmental conditions.

Grossman, G.D., Freeman, M.C., Moyle, P.B., Whitaker, J.O. 1985. Stochasticity and Assemblage Organization in an Indiana Stream Fish Assemblage.The American Naturalist, 126(3): 275-285.

Abstract
In 1982, Grossman et al. purported to demonstate that a stream fish assemblage was probably affected by unpredictable environmental disturbances than by interactive processes such as competition. The main purpose of that paper was to interest ecologists in the possibility that stream fish and invertebrate assemlages may be organized through processes fundamentally different from those addressed by the bulk of ecological theory. Grossman et al. (1982) provoked a series of critical rebuttals (Herbold 1984; Rahel et al. 1984; Yant et al. 1984), and our purpose here is to clarify some of the issues raised by these critiques.

Grossman, G.D., Hill, J.H. 1993. An Energetic Model of Microhabitat Use for Rainbow Trout and Rosyside Dace. Ecology, 74(3): 685-698.

Abstract
We constructed an energetic model to determine the optimal focal point current velocity (i.e., microhabitat) for rainbow trout (Oncorhynchus mykiss) and rosyside dace (Clinostomus funduloides) in Coweeta Creek, a fifth-order stream in North Carolina, USA. Energetic costs were evaluated by quantifying the metabolic expenditure associated with swimming at a given velocity. We estimated benefits by measuring potential energetic gains of feeding at a given velocity. This included estimates of the ability of the fish to capture prey at different current velocities as well as estimates of the frequency and the energy content of drifting prey at various velocities. We derived separate models for small (53-70 mm SL [standard length]) and medium (71-125 mm SL) trout, and medium (47- 52 mm SL) and large (53-70 mm SL) dace for all seasons, deriving net energy gain as a function of current velocity. We predicted fishes would occupy velocities at which net energy gain was maximized. Predicted velocities were compared with those utilized by fishes inhabiting Coweeta Creek. Optimal velocities predicted by energetic models ranged from 7.7 to 22.1 cm/s, and closely matched actual velocity use (average deviation = 2.6 cm/s). Prey capture success appeared to be the most important component in the models. Consequently, we constructed models based solely upon aspects of capture success; the average deviation from velocity use with these models was only 1.8 cm/s. Thus, the ability of dace and trout to capture prey at varying velocities appears to be the dominant factor affecting microhabitat selection in these species.

Grossman, G.D., J.F. Dowd, and M. Crawford. 1990. Assemblage stability in stream fishes: a review. Environmental Management 14(5): 661-671.

Abstract
The stability of nine stream fish assemblages are represented by coefficients of variation of population size. High coefficients of variation (over 96%) indicate that most assemblages were quite variable. Coefficient of variation estimates were not significantly affected by: (1) years of study, (2) mean abundance, (3)familial classification, or (4) mean interval between collections. The high variability of many stream fish assemblages suggests that it may be difficult to detect the effects of anthropogenic disturbances using population data alone. Long-term studies of the ecological characteristics of undisturbed stream fish assemblages are needed to provide benchmarks to compare to disturbed systems.

Grossman, G.D., K. McDaniel, and R.E. Ratajczak Jr. 2002. Demographic characteristics of female mottled sculpin, Cottus bairdi, in the Coweeta Creek drainage, North Carolina. Environmental Biology of Fishes 63: 299-308.

Abstract
We quantified: (1) growth rate, (2) length-mass relationships, (3) size- and age-specific fecundity, (4) egg sizefrequencies, and (5) size- and age-specific egg diameter relationships for reproductively active female C. bairdi from one of the southern-most extant populations of this species (Coweeta Creek drainage, North Carolina). Gravid females were collected during February and March in 1993v1995, and 1998. Cottus bairdi reached an age of 7+and 79mm standard length. The youngest and smallest gravid female collected was a 41mm 1+ individual. Mature 1+ females were not uncommon and we collected 21 during our study. All females older than age 2 were mature. Mean fecundity for C. bairdi at Coweeta was 71 eggs (range 9v166 eggs). We found significant positive relationships between fecundity and female length, weight and age. Female length and weight also significantly affected mean egg diameter, although the relationship was not linear. Neither female size or age significantly affected mean maximum egg diameters. Female C. bairdi from the Coweeta Creek drainage possess a unique suite of reproductive characteristics that may represent adaptations to the local selective regime or ecophenotypic variation.

Grossman, G.D., Nickerson, D.M., Freeman, M.C. 1991. Principal Component Analyses of Assemblage Structure Data: Utility of Tests Based on Eigenvalues. Ecology, 72(1): 341-347.

Abstract
We examined the ability of eigenvalue tests to distinguish field-collected from random, assemblage structure data sets. Eight published time series of species abun- dances were used in the analysis, including data sets for: fishes, birds, mammals, stream benthos, and crabs. To test the efficacy of eigenvalue tests, we constructed 1000 randomly generated data sets for each real data set, whose means and variances were identical to the means and variances of the original data matrices. The data sets were then subjected to a principal components analysis (PCA) and eigenvalue tests used to identify significant ei- genvalues for both correlation and covariance matrix solutions. We also examined the effects of: (1) number of species (= number of variables), (2) number of samples (= rep- lication), and (3) variance structure, on the performance of the test. Using PCA's based on the correlation matrix and with sample sizes typically encountered in the field, the eigenvalue tests generally performed at the .05 level when a = .01. Slightly poorer results were obtained with the covariance matrix. Increasing the number of samples to at least three times the number of species generally gave a level coverage for an a level test (i.e., a = .05, .01). Increasing variance in the data set only affected test outcomes at levels of replication less than twice the number of species. We conclude that the eigenvalue tests can be used to detect patterns in PCA's of assemblage structure data, if the number of samples is at least three times the number of species and either a covariance or correlation matrix solution is used. It is assumed that these patterns represent ecologically meaningful patterns of variation.

Grossman, G.D., P.A. Rincon, M.D. Farr, and R.E. Ratajczak Jr. 2002. A new optimal foraging model predicts habitat use by drift-feeding stream minnows. Ecology of Freshwater Fish. 11: 2-10.

Abstract
There is substantial need for models that accurately predict habitat selection by fishes for purposes ranging from the elaboration of ecological theory to the preservation of biodiversity. We have developed a new and highly tractable optimal foraging model for drift-feeding fishes that is based on the profitably of occupying varying focal-point velocities in a stream. The basic model can be written as: Ix=(Ex*Px) = {(D*A*V)*[1/(1 + e (b + cV))]} vSX, where: (1) IX is the net energy intake at velocity x; (2) E is prey encounter rate; (3) P is prey capture success rate which can be modeled as 1/(1 + e (b + cV)) where b and c are fitting constants from the prey capture success curve; (4) D is the energy content of prey (J/m3) in the drift; (5) A is the visual reactive area of the fish; (6) V is velocity (cm/s); and (7) S is the cost of maintaining position (J/s). Given that D, A and S can be considered constant over the range of velocities occupied by these fishes, the model reduces to e (b + cV) = 1/(cV-1) which we solved iteratively to yield an optimal focal-point velocity for species in each sample. We tested the model by comparing its predictions to the mean focal-point velocities (i.e. microhabitats) occupied by four species of drift-feeding minnows in two sites in a stream in North Carolina, USA. The model successfully predicted focal-poitvelocities occupied by these species (11 out of 14 cases) in three seasonal samples collected over 2 years at two sites. The unsuccessful predictions still were within 2 cm/s of the 95% confidence intervals of mean velocities occupied by fishes, whereas, the overall mean deviation between optimal velocities and mean fish velocities was small (range = 0.9 and 3.3 cm/s for the war paint shiner and the Tennessee shiner, respectively). Available focal point velocities ranged from 0-76to 0-128 cm/s depending on site and season. Our findings represent one of the more rigorous field tests of an optimal foraging/habitat selection model for aquatic organisms because they encompass multiple species and years, and for one species, multiple sites. Because of the case of parameterization of our model, it should be readily testable in a range of lotic habitats. If validated in other systems, the model should provide critical habitat information that will aid in the management of riverine systems and improve the performance of a variety of currently used management models (e.g. instream flow incremental methodology (IFIM) and total maximum daily load calculations(TMDL).

Grossman, G.D., R.E. Ratajczak Jr., and M.K. Crawford. 1995. Do rock bass (Ambloplites rupestris) induce microhabitat shifts in mottled sculpin (Cottus bairdi)? Copeia. 2: 343-353.

Abstract
In Coweeta Creek, North Carolina , mottled sculpin (Cottus bairdi) co-occurred seasonally with a potential predator, rock bass (Ambloplites rupestris). We conducted experiments to determine whether rock bass affected microhabitat use by sculpin in an artificial stream. The general behavior and microhabitat use of both species in the artificial stream resembled those observed in Coweeta Creek. When all microhabitat observations were pooled, there was little evidence of predator-induced shifts by sculpin. However, at night in trials without predators, sculpin generally occurred farther from shelter, over greater amounts of gravel and lower quantities of erosional substrata. When we added predators, however, this response was obviated. Nonetheless, the lack of strong responses by sculpin to rock bass, coupled with their co-occurence only during seasons of low metabolic activity, lead us to suspect that rock bass do not produce strong shifts in microhabitat use by most sculpin in the Coweeta drainage.

Grossman, G.D., R.E. Ratajczak Jr., J.T. Petty, M.D. Hunter, J.T. Peterson, and G. Grenouillet. 2006. Population dynamics of mottled sculpin (pisces) in variable environment: information theoretic approaches. Ecological Monographs. 76(2): 217-234.

Abstract
We used strong inference with Akaike¼s Information Criterion (AIC) to assess the processes capable of explaining long-term (1984v1995) variation in the per capita rate of change of mottled sculpin (Cottus bairdi) populations in the Coweeta Creek drainage (USA). We sampled two fourth- and one fifth-order sites (BCA [uppermost], BCB, and CC [lowermost]) along a downstream gradient, and the study encompassed extensive flow variation. Physical habitat availability varied significantly both within and among the sites. Sculpin densities in all sites were highly stable (coefficients of variation 5 0.23 0.41) and sampling variability was low (coefficients of variation 5 0.11v0.15). Population stability was positively associated with habitat stability, and the only significant correlations of population parameters among sites involved juveniles. Sculpin densities were significantly higher in BCB than in CC. The data suggest that, despite their proximity, the dynamics of populations within the sites are being determined by small scale (i.e., 30v50 m) rather than broad-scale spatial processes. Both AIC and Dennis and Taper analyses indicated that simple density dependence had the greatest ability to explain variation in r for all life-history classes in all sites (AIC, seven of nine cases; Dennis and Taper, nine of nine cases). Multiprocess models had little explanatory power. When adults were removed from two sites, juvenile sculpin shifted into microhabitats formerly occupied by adults. No shifts occurred in control sites. Consequently, it is likely that the patterns of density dependence observed in all three sites were a consequence of intraspecific competition for space. Our findings argue for a multitiered approach to the study of population variation, one that encompasses long-term monitoring, spatial variation, and experimental testing of potential mechanisms.

Grossman, G.D., R.E. Ratajczak Jr., M.K. Crawford, and M.C. Freeman. 1998. Assemblage of organization in stream fishes: effects of environmental variation and interspecific interactions. Ecological Monographs. 68(3): 395-420.

Abstract
We assessed the relative importance of environmental variation, interspecific competition for space, and predator abundance on assemblage structure and microhabitat use in a stream fish assemblage inhabiting Coweeta Creek, North Carolina, USA. Our study encompassed a 10-yr time span (1983-1992) and included some of the highest and lowest flows in the last 58 years. We collected 16 seasonal samples which included data on: (1) habitat availability (total and microhabitat) and microhabitat diversity, (2) assemblage structure, and (3) microhabitat use and overlap. We classified habitat availability data on the basis of year, season, and hydrologic period. Hydrologic period (i.e., pre-drought [PR], drought [D], and post-drought [PO]) represented the temporal location of a sample with respect to a four-year drought that occurred during the study. Hydrologic period explained a greater amount of variance in habitat availability data than either season or year. Total habitat availability was significantly greater during PO than in PR or D, although microhabitat diversity did not differ among either seasons or hydrologic periods. There were significantly fewer high-flow events (i.e., + 2.1 m3/s) during D than in either PR or PO periods. We observed a total of 16 species during our investigation, and the total number of species was significantly higher in D than in PR samples. Correlation analyses between the number of species present (total and abundant species) and environmental data yielded limited results, although the total number of species was inversely correlated with total habitat availability. A cluster analysis grouped assemblage structure samples by hydrologic period rather than season or year, supporting the contention that variation in annual flow had a strong impact on this assemblage. The drought had little effect on the numerical abundance of benthic species in this assemblage; however, a majority of water-column species increased in abundance. The increased abundances of water-column species may have been related to the decrease in high-flow events observed during the drought. Such high-flow events are known to cause mortality in stream fishes. Microhabitat use data showed that species belonged to one of three microhabitat guilds: benthic, lower water column, and mid water column. In general, species within the same guild did not exhibit statistically distinguishable patterns of microhabitat use, and most significant differences occurred between members of different guilds. However, lower water-column guild species frequently were not separable from all members of either benthic or mid-water-column species. Variations in the abundance of potential competitors or predators did not produce strong shifts in microhabitat use by assemblage members. Predators were present in the site in only 9 of 16 seasonal samples and never were abundant. In conclusion, our results demonstrate that variability in both mean and peak flows had a much stronger effect on the structure and use of spatial resources within this assemblage then either interspecific competition for space or predation. Consequently, we suspect that the patterns in both assemblage structure and resource use displayed by fishes in Coweeta Creek arose from the interaction between environmental variation and species-specific evolutionary constraints on behavior, morphology, and physiology.

Grossman, Gary D., Robert E. Ratajczak, C. Michael Wagner and J. Todd Petty. 2010. Dynamics and Regulation of the southern brook trout (Salvelinus fontinalis) population in an Appalachian stream. Freshwater Biology 55:1494-1508.

Abstract
1. We used information theoretic statistics [Akaike’s Information Criterion (AIC)] and regression analysis in a multiple hypothesis testing approach to assess the processes capable of explaining long-term demographic variation in a lightly exploited brook trout population in Ball Creek, NC. We sampled a 100-m-long second-order site during both spring and autumn 1991–2004, using three-pass electrofishing. 2. Principle component analysis indicated that the site had lower average velocity, greater amounts of depositional substrata and lower amount of erosional substrata during the 1999–2002 drought than in non-drought years. In addition, drought years had lower flows, and lower variation in flows, than non-drought years. 3. Both young-of-the-year (YOY) and adult densities varied by an order of magnitude during the study. AIC analysis conducted on regressions of per capita rate of increase versus various population and habitat parameters for the population, adults and YOY, for both spring and autumn data sets, indicated that simple density dependence almost always was the only interpretable model with Akaike weights (wi) ranging from 0.262 to 0.836. 4. Growth analyses yielded more variable results, with simple density dependence being the only interpretable model for both adult spring data (wi = 0.999) and YOY autumn data (wi = 0.905), and positive density dependence (wi = 0.636) and simple density independence (wi = 0.241) representing interpretable models for spring YOY data. 5. We detected a significant stock–recruitment relationship between both spring and autumn densities of adults in year t and autumn YOY density in year t + 1. Finally, spring YOY density was positively correlated with both autumn YOY density and spring mean YOY standard length (SL), suggesting that processes affecting recruitment show residual effects at least in the first year of life. This population appears to be regulated primarily by density-dependent processes, although high flows also negatively affected mean SLs of YOY.

Grubaugh, J.W., J.B. Wallace, and E.S. Houston. 1996. Longtitudinal changes of macroinvertebrate communities along an Appalachian stream continuum. Canadian Journal of Fisheries and Aquatic Sciences 53: 896-909.

Abstract
Richness and mean annual abundance and biomass of benthic taxa were measured in prevalent habitats along a first-through seventh-order stream continuum in the southern Appalachian Mountains (United States). Richness was greatest in midorder reaches, and benthic densities were highest in cobble habitat, followed by bedrock, pebble-gravel, and depositional areas. Abundance-based estimates of function feeding-group composition were dominated by collector-gatherers and changed little with habitat. In contrast, biomass-based estimates differed greatly among habitats: collector-filterers generally dominated cobble and bedrock areas; collector-gatherers, in pebble-gravel; and shredders and collector-gatherers, in depositional habitats. When functional-group biomass estimates were weighted for relative habitat availability along the continuum, patterns of benthic community composition generally matched predictions of the river continuum concept (RCC), although localized changes in stream geomorphology also influenced community structure. Habitat-weighted abundance estimates did not produce similar trends. Because RCC predictions are based on benthic biomass, caution and qualification must be exercised when using abundance data to test RCC predictions.

Grubaugh, J.W., J.B. Wallace, and E.S. Houston. 1997. Production of benthic macroinvertebrate communities along a southern Appalachian river continuum. Freshwater Biology 37: 581-596.

Abstract
1. Annual production was estimated for macroinvertebrate communities of principle habitats along a first- to seventh-order river continuum in the southern Appalachian Mountains (U.S.A.). Annual production was relatively low in depositional habitats, pebble/gravel substrata, and on cobble devoid of plant biomass (Mosses and hydrophytes). Production was greater in bedrock habitats and greatest on hydrophyte-covered cobble, with estimates reaching 364 g AFDM (ash-free dry mass) m-2yr-1 in a sixth-order river reach. Annual production in depositional habitats was correlated to standing crops of benthic organic material (BOM) in low-order stream reaches but not in high-order reaches, indicating differences in BOM availability with stream size. In cobble, pebble/gravel and bedrock habitats production was significantly correlated to standing crops of aquatic plants, which can stabilize strata and enhance access of collector-filtering invertebrates to entrained food resources.2. By accounting for proportional availability of habitats along the continuum, estimates of total production ranged from 5 to 154 g AFDM m-2 yr-1, and increased significantly with stream size. Annual production estimated for sixth- and seventh-order reaches of the continuum were amongst the highest reported thus far for lotic systems. Organization of the benthic community along the continuum, based on production estimates for individual functional feeding-groups, generally supported predictions of the River Continuum Concept (RCC): shredder contributions were greatest in low-order reaches and declined downstream; scraper percentages were greatest in the middle of the continuum; collector-filterer contributions increased with the increased stream size. Longitudinal trends for collector-gatherers and predators did not support RCC predictions; these groups appeared to be influenced by localized changes in habitat availability and occurrence of vertebrate predators along the continuum.

Grzenda, A.R., H.P. Nicholson, J.I. Teasley, and J.H. Patric. 1964. DDT residues in mountain stream water as influenced by treatment practices. Journal of Economic Entomology 57: 615-618.

Abstract
DDT residues in Coweeta streams after spraying for elm spanworm by airplane in 1961 and by helicopter in 1962 are compared. DDT contamination of Coweeta Creek was negligible after precise application by helicopter in upslope and ridge areas.

Gulis, V., A.D. Rosemond, K. Suberkropp, H.S. Weyers, and J.P. Benstead. 2004. Effects of nutrient enrichment on the decomposition of wood and associated microbial activity in streams. Freshwater Biology. 49: 1437-1447.

Abstract
(1) We determined the effects of nutrient enrichment on wood decomposition rates and microbial activity during a 3-year study in two headwater streams at Coweeta Hydrologic Laboratory, NC, U.S.A. After a 1-year pretreatment period, one of the streams was continuously enriched with inorganic nutrients (nitrogen and phosphorus) for 2 years while the other stream served as a reference. We determined the effects of enrichment on both wood veneers and sticks, which have similar carbon quality but differ in physical characteristics (e.g. surface area to volume ratios, presence of bark) that potentially affect microbial colonization and activity. (2) Oak wood veneers (0.5 mm thick) were placed in streams monthly and allowed to decompose for approximately 90 days. Nutrient addition stimulated ash-free dry mass loss and increased mean nitrogen content, fungal biomass and microbial respiration on veneers in the treatment stream compared with the reference. The magnitude of the response to enrichment was great, with mass loss 6.1 times, percent N, fungal biomass and microbial respiration approximately four times greater in the treatment versus reference stream. (3) Decomposition rate and nitrogen content of maple sticks (ca. 1-2 cm diameter) also increased; however, the effect was less pronounced than for veneers. Wood response overall was greater than that determined for leaves in a comparable study, supporting the hypothesis that response to enrichment may be greater for lower quality organic matter (high C : N) than for higher quality (low C : N) substrates. (4) Our results show that moderate nutrient enrichment can profoundly affect decomposition rate and microbial activity on wood in streams. Thus, the timing and availability of wood that provides retention, structure, attachment sites, and food in stream ecosystems may be affected by nutrient concentrations raised by human activities.

Gulis, V., and K. Suberkropp. 2003. Effect of inorganic nutrients on relative contributions of fungi and bacteria to carbon flow from submerged decomposing leaf litter. Microbial Ecology. 45: 11-19.

Abstract
The relative contributions of fungi and bacteria to carbon flow from submerged decaying plant litter at different levels of inorganic nutrients (N and P) were studied. We estimated leaf mass loss, fungal and bacterial biomass and production, and microbial respiration and constructed partial carbon budgets for red maple leaf disks precolonized in a stream and then incubated in laboratory microcosms at two levels of nutrients. Patterns of carbon flow for leaf disks colonized with the full microbial assemblage were compared with those colonized by bacteria but in which fungi were greatly reduced by placing leaf disks in colonization chambers sealed with membrane filters to exclude aquatic hyphomycete conidia but not bacterial cells. On leaves colonized by the full microbial assemblage, elevated nutrient concentrations stimulated fungi and bacteria to a similar degree. Peak fungal and bacterial biomass increased by factors of 3.9 and 4.0; cumulative production was 3.9 and 5.1 times higher in the high nutrient in comparison with the low nutrient treatment, respectively. Fungi dominated the total microbial biomass (98.4 to 99.8%) and cumulative production (97.3 and 96.5%), and the fungal yield coefficient exceeded that of bacteria by a factor of 36 and 27 in low- and high-nutrient treatments, respectively. Consequently, the dominant role of fungi in leaf decomposition did not change as a result of nutrient manipulation. Carbon budgets indicated that 8% of leaf carbon loss in the low-nutrient treatment and 17% in the high-nutrient treatment were channeled to microbial (essentially fungal) production. Nutrient enrichment had a positive effect on rate of leaf decomposition only in microcosms with full microbial assemblages. In treatments where fungal colonization was reduced, cumulative bacterial production did not change significantly at either nutrient level and leaf decomposition rate was negatively affected (high nutrients), suggesting that bacterial participation in carbon flow from decaying leaf litter is low regardless of the presence of fungi and nutrient availability. Moreover, 1.5 and 2.3 times higher yield coefficients of bacteria in the reduced fungal treatments at low and high nutrients, respectively (percentage of leaf carbon loss channeled to bacterial production), suggest that bacteria are subjected to strong competition with fungi for resources available in leaf litter.

Gulis, V., and K. Suberkropp. 2003. Interactions between stream fungi and bacteria associated with decomposing leaf litter at different levels of nutrient availability. Aquatic Microbial Ecology. 30: 149-157.

Abstract
We examined the potential for interactions between aquatic hyphomycetes and bacteria isolated from leaves decaying in a headwater stream. In agar plate assays, culture filtrates of each of 28 aquatic hyphomycete isolates tested (5 species) inhibited bacterial growth (16 Gram-negative bacterial isolates belonging to 6 colony morphotypes were tested). Inhibition of bacterial growth occurred in 20% of the combinations. To determine whether such interactions could occur on decomposing leaves, Articulospora tetracladia (isolate 24-4) and bacterial isolate B2NPM3-1 (tentatively placed in Comamonadaceae) were grown in axenic and dual cultures on leaf litter in microcosms. Performance of both microorganisms was estimated by measuring leaf mass loss, fungal and bacterial biomass, conidia production, respiration and calculating carbon flow through different microbial compartments in 2 treatments that differed with respect to inorganic nutrient (N and P) concentrations. High fungal antagonistic activity demonstrated in plate assays was not corroborated in microcosms. Cumulative Articulospora tetracladia production decreased 21 to 24% in 2-membered microcosms regardless of nutrient level, whereas the bacterial isolate exhibited a differential response (1.7 times lower cumulative production in the low nutrient and 52% increase in the high nutrient treatment in 2-membered cultures compared with axenic cultures), suggesting that nutrient availability may modify microbial interactions. Fungal performance (yield coefficient and production efficiency) was not affected in 2-membered microcosms, whereas the bacterial yield coefficient was 1.7 to 2.2 times lower when grown with the fungus in comparison to axenic cultures. We observed only antagonistic or competitive interactions and no signs of synergistic relationships causing faster leaf litter decomposition or resulting in enhanced microbial production. Overall, the interactions were relatively mild and did not affect fungal dominance in the transformation of leaf organic matter.

Gulis, V., and K. Suberkropp. 2003. Leaf litter decomposition and microbial activity in nutrient-enriched and unaltered reaches of a headwater stream. Freshwater Biology. 48:123-134.

Abstract
1. Decomposition of red maple (Acer rubrum) and rhododendron (Rhododendron maximum) leaves and activity of associated microorganisms were compared in two reaches of a headwater stream in Coweeta Hydrologic Laboratory, NC, U.S.A. The downstream reach was enriched with ammonium, nitrate, and phosphate whereas the upstream reach was not altered. 2. Decomposition rate, microbial respiration, fungal and bacterial biomass, and the sporulation rate of aquatic hyphomycetes associated with decomposing leaf material were significantly higher for both leaf types in the nutrient-enriched reach. Species richness and community structure of aquatic hyphomycetes also exhibited considerable changes with an ncrease in the number of fungal codominants in the nutrient-enriched reach. 3. Fungal biomass was one to two orders of magnitude greater than bacterial biomass in both reaches. Changes in microbial respiration rate corresponded to those in fungal biomass and sporulation, suggesting a primary role of fungi in leaf decomposition. 4. Nutrient enrichment increased icrobial activity, the proportion of leaf carbon channelled through the microbial compartment and the decomposition rate of leaf litter.

Gulis, V., and K. Suberkropp. 2004. Effects of whole-stream nutrient enrichment on the concentration and abundance of aquatic hyphomycete conidia in transport. Mycologia. 96(1): 57-65.

Abstract
The concentrations and relative abundances of aquatic hyphomycete conidia in water were followed during a three-year study in two headwater streams at Coweeta Hydrologic Laboratory, North Carolina, using the membrane-filtration technique. After a one-year pretreatment period, one of the streams was enriched continuously with inorganic nutrients (N+P) for two years while the other stream served as the reference. This ecosystem-level nutrient manipulation resulted in concentrations of aquatic hyphomycete conidia in the water of the treated stream that were 4.5-6.9 times higher than the concentrations observed during the pretreatment period and in the reference stream. Nutrient enrichment led to an increase in the number of fungal species detected on each sampling date. Changes in dominance patterns and relative abundances of individual species also were detected after treatment. Nutrient addition stimulates the reproductive activity of aquatic hyphomycetes, their colonization success, and fungal-mediated leaf-litter decomposition. Such changes in the activity of the fungal community might affect higher trophic levels in lotic ecosystems.

Gulis, V., K.A. Kuehn, L.N. Schoettle, D. Leach, J.P. Benstead, and A.D. Rosemond. 2017. Changes in nutrient stoichiometry, elemental homeostasis and growth rate of aquatic litter-associated fungi in response to inorganic nutrient supply. ISME Journal (Multidisciplinary Journal of Microbial Ecology) 10.1038/ismej.2017.123

Abstract
Aquatic fungi mediate important energy and nutrient transfers in freshwater ecosystems, a role potentially altered by widespread eutrophication. We studied the effects of dissolved nitrogen (N) and phosphorus (P) concentrations and ratios on fungal stoichiometry, elemental homeostasis, nutrient uptake and growth rate in two experiments that used (1) liquid media and a relatively recalcitrant carbon (C) source and (2) fungi grown on leaf litter in microcosms. Two monospecific fungal cultures and a multi-species assemblage were assessed in each experiment. Combining a radioactive tracer to estimate fungal production (C accrual) with N and P uptake measurements provided an ecologically relevant estimate of mean fungal C:N:P of 107:9:1 in litter-associated fungi, similar to the 92:9:1 obtained from liquid cultures. Aquatic fungi were found to be relatively homeostatic with respect to their C:N ratio (~11:1), but non-homeostatic with respect to C:P and N:P. Dissolved N greatly affected fungal growth rate and production, with little effect on C:nutrient stoichiometry. Conversely, dissolved P did not affect fungal growth and production but controlled biomass C:P and N:P, probably via luxury P uptake and storage. The ability of fungi to immobilize and store excess P may alter nutrient flow through aquatic food webs and affect ecosystem functioning.

Gulis, V., Suberkropp, K., Rosemond, A. 2008. Comparison of Fungal Activities on Wood and Leaf Litter in Unaltered and Nutrient-Enriched Headwater Streams. Applied and Environmental Microbiology. 74(4):1094-1101

Abstract
Fungi are the dominant organisms decomposing leaf litter in streams and mediating energy transfer to other trophic levels. However, less is known about their role in decomposing submerged wood. This study provides the first estimates of fungal production on wood and compares the importance of fungi in the decomposition of submerged wood versus that of leaves at the ecosystem scale. We determined fungal biomass (ergosterol) and activity associated with randomly collected small wood (<40 mm diameter) and leaves in two southern Appalachian streams (reference and nutrient enriched) over an annual cycle. Fungal production (from rates of radiolabeled acetate incorporation into ergosterol) and microbial respiration on wood (per gram of detrital C) were about an order of magnitude lower than those on leaves. Microbial activity (per gram of C) was significantly higher in the nutrient-enriched stream. Despite a standing crop of wood two to three times higher than that of leaves in both streams, fungal production on an areal basis was lower on wood than on leaves (4.3 and 15.8 g C m 2 year 1 in the reference stream; 5.5 and 33.1 g C m 2 year 1 in the enriched stream). However, since the annual input of wood was five times lower than that of leaves, the proportion of organic matter input directly assimilated by fungi was comparable for these substrates (15.4 [wood] and 11.3% [leaves] in the reference stream; 20.0 [wood] and 20.2% [leaves] in the enriched stream). Despite a significantly lower fungal activity on wood than on leaves (per gram of detrital C), fungi can be equally important in processing both leaves and wood in streams.

Gurtz, M.E., and J.B. Wallace. 1984. Substrate-mediated response of stream invertebrates to disturbance. Ecology 65(5): 1556-1569.

Abstract
The response of aquatic invertebrates to a major watershed disturbance, clear-cutting, was examined in a second-order stream. For 21 mo after the start of logging, invertebrates were sampled in four substrate types: rock face, cobble riffles, pebble riffles, and sand. More taxa increased in density (compared with a nearby reference stream) in moss-covered rock face than in any other substrate; cobble riffles were next, followed by pebble riffles and sand. Conversely, the number of taxa with significant reductions in density was highest for sand substrates. Among functional groups of insects, collector-gatherers and scrapers increased, while the dominant shredder declined. The differential response of invertebrates among substrates suggests that biological stability is closely coupled with physical stability; however, moss associated with larger particles may be a factor in enhancing the biological stability.

Gurtz, M.E., and J.B. Wallace. 1986. Substratum-production relationships in net-spinning caddisflies (Trichoptera) in disturbed and undisturbed hardwood catchments. Journal of North American Benthological Society 5(3): 230-236.

Abstract
The effect of substratum on production of two species of net-spinning Trichoptera was examined in two second-order Southern Appalachian streams: Hugh White Creek, a reference stream draining an undisturbed hardwood catchment, and Big Hurricane Branch, which drains a catchment that was clear cut during the first six months of the study. Surber samples were collected monthly for 21 months in four common substrata in each stream: moss-covered rock face, cobble riffle, pebble riffle, and sandy reach. Both species showed distinct substratum preferences. Abundances and production were significantly higher in rock face > cobble riffle > pebble riffle > sandy reach in both streams. Differences in production between streams may be related more to geomorphic differences between streams than to effects of logging on these two species.

Gurtz, M.E., J.R. Webster, and J.B. Wallace. 1980. Seston dynamics in southern Appalachian streams: effects of clear-cutting. Canadian Journal of Fisheries and Aquatic Sciences 37: 624-631.

Abstract
Suspended particulate matter was studied from July 1977 to July 1978 in two second-order streams in the southern Appalachian Mountains. In the first stream, which drains an undisturbed hardwood forest watershed, seston concentrations fluctuated with season and with storm flows. Most organic and inorganic particles were smaller than 105 um diameter. The second stream drains a watershed that was clear-cut in early 1977. Increased levels of both organic and inorganic seston were found in the latter stream, especially beginning 1 year after clear-cutting. Particles larger than 234 um in diameter accounted for most of the increases in inorganic seston. We hypothesize that eventual recovery of the stream will be limited by the rate of recovery of the surrounding terrestrial ecosystem.

Gustafson, S., Heynen, N., Rice, J.L., Gragson, T., Shepherd, J.M., and Strother, C. (2014). Megapolitan political ecology and urban metabolism in southern Appalachia. The Professional Geographer. (DOI:10.1080/00330124.2014.905158)

Abstract
Drawing on megapolitan geographies, urban political ecology, and urban metabolism as theoretical frameworks, this paper theoretically and empirically explores ‘megapolitan political ecology.’ First, we elucidate a theoretical framework in the context of southern Appalachia and, in particular, the Piedmont megapolitan region. We argue that the megapolitan region is a useful scale through which to understand urban metabolic connections that constitute this rapidly urbanizing area. We also push the environmental history and geography literature of the US South and southern Appalachia to consider the central role urban metabolic connections play in the region’s pressing social and environmental crises. Secondly, we empirically illuminate these human and non-human urban metabolisms across the Piedmont megapolitan region using data from the Coweeta Long-Term Ecological Research program. We especially highlight here a growing ‘Ring of Asphalt’ that epitomizes several developing changes to patterns of metabolism. We conclude by suggesting that these Coweeta LTER data show that changing urban metabolism, ranging from flows of people to flows of water, poses a complicated problem for regional governance and vitality in the future.

Haefner, J.D., and J.B. Wallace. 1981. Production and potential seston utilization by Parapsyche cardis and Diplectrona modesta (Trichoptera. Hydropsychidae) in two streams draining contrasting southern Appalachian watersheds. Environmental Entomology 10(4):433-441

Abstract
Production of Parapsyche cardis Ross and Diplectrona modesta Banks was estimated in two first-order southern Appalachian streams. One stream drains a natural undisturbed hardwood watershed and the other a watershed subjected to several disturbances. Since 1968 the latter has been allowed to undergo natural succession. Both hydropsychid species were univoltine in each stream. Production estimates were higher for both species in the stream draining the disturbed watershed, attributable to: (1) more suitable habitat, (2) higher densities of prey species, and (3) potentially enhanced food quality resulting from a 200-fold greater NO3-N concentration. Estimates of animal tissue consumption are several times higher than the invertebrate drift from each watershed, suggesting that the major impact of these net spinners is on the animal fraction of the seston.

Haefner, J.D., and J.B. Wallace. 1981. Shifts in aquatic insect populations in a first-order southern Appalachian stream following a decade of old field succession. Canadian Journal of Fisheries and Aquatic Science 38: 353-359.

Abstract
Aquatic insect populations were sampled on two first-order southern Appalachian streams. Grady Branch, the control stream, drains an undisturbed hardwood watershed. Sawmill Branch has undergone natural succession since 1968, from artificially maintained grassland to hardwood coppice dominated by black locust. Aquatic insect densities on Sawmill Branch were about twice those on Grady Branch, a reversal of results obtained by a similar study in 1968. It is suggested that changes in watershed vegetation influence long-term changes in aquatic insect populations, including a shift toward an allochthonous energy base.

Hagen, E.M., J.R. Webster, and E.F. Benfield. 2006. Are leaf breakdown rates a useful measure of stream integrity along an agricultural landuse gradient? Journal of the North American Benthological Society. 25(2): 330-343.

Abstract
Biological indicators often are used to assess and manage water quality in anthropogenically altered stream systems. Leaf breakdown has the potential to be a good indicator of stream integrity because it integrates a variety of biological, chemical, and physical conditions. Red maple (Acer rubrum L.) leaf breakdown rates were measured along a gradient of agricultural land use in southern Appalachian streams to assess the use of leaf breakdown rates as a measure of stream integrity. Landuse categories included forested, light agriculture, moderate agriculture, and heavy agriculture. Leaf breakdown rates were related to landuse category but did not differ significantly among landuse categories. Nutrient concentration, temperature, and sedimentation increased, and dissolved O2 decreased along the landuse gradient from forest to heavy agriculture. Macroinvertebrate richness, macroinvertebrate density, and shredder density were the only significant predictors of leaf breakdown rates. We conclude that leaf breakdown rates may not be a useful indicator of stream integrity because of the confounding effects that agricultural land use has on breakdown rates.

Hagen, Elizabeth M. Matthew E. McTammany, Jackson R. Webster, Ernest F. Benfield. 2010. Shifts in allochthonous input and autochthonous production in streams along an agricultural land-use gradient. Hydrobiologia. 655(1):61-77.

Abstract
Relative contributions of allochthonous inputs and autochthonous production vary depending on terrestrial land use and biome. Terrestrially derived organic matter and in-stream primary production were measured in 12 headwater streams along an agricultural land-use gradient. Streams were examined to see how carbon (C) supply shifts from forested streams receiving primarily terrestrially derived C to agricultural streams, which may rely primarily on C derived from algal productivity. We measured allochthonous input, chlorophyll a concentration, and periphyton biomass in each stream, and whole-stream metabolism in six streams. Our results suggest a threshold between moderate- and heavy-agriculture land uses in which terrestrially derived C is replaced by in-stream algal productivity as the primary C source for aquatic consumers. A shift from allochthonous to autochthonous production was not evident in all heavy-agriculture streams, and only occurred in heavy-agriculture streams not impacted by livestock grazing. We then compared our findings to rates of allochthonous input and GPP in streams with minimal human influences in multiple biomes to assess how land-use practices influence C sources to stream ecosystems. The proportion of C derived from allochthonous versus autochthonous sources to heavyagriculture streams was most similar to grassland and desert streams, while C sources to forested, light-, and moderate-agriculture streams were more similar to deciduous and montane coniferous forest streams. We show that C source to streams is dependent on land use, terrestrial biome, and degradation of in-stream conditions. Further, we suggest that within a biome there seems to be a compensation such that total C input is nearly equal whether it is from allochthonous or autochthonous sources.

Hain EF, Kennen JG, Caldwell PV, Nelson SAC, Sun G, McNulty SG. Using regional scale flow–ecology modeling to identify catchments where fish assemblages are most vulnerable to changes in water availability. Freshwater Biol. 2017;00:1–18. https://doi.org/10.1111/fwb.1304

Abstract
1. Streamflow is essential for maintaining healthy aquatic ecosystems and for supporting human water supply needs. Changes in climate, land use and water use practices may alter water availability. Understanding the potential effect of these changes on aquatic ecosystems is critical for long-term water management to maintain a balance between water for human consumption and ecosystem needs. 2. Fish species data and streamflow estimates from a rainfall-runoff and flow routing model were used to develop boosted regression tree models to predict the relationship between streamflow and fish species richness (FSR) under plausible scenarios of (1) water withdrawal, (2) climate change and (3) increases in impervious surfaces in the Piedmont ecoregion of North Carolina, U.S.A. Maximum monthly flow, the fraction of total flow originating from impervious surface runoff, coefficient of monthly streamflow variability, and the specific river basin accounted for 50% of the variability in FSR. This model was used to predict FSR values for all twelve-digit Hydrological Unit Code catchments (HUC-12s) in the North Carolina Piedmont under current flow conditions and under water withdrawal, climate change and impervious surface scenarios. 3. Flow–ecology modeling results indicate that predicted FSR declined significantly with increased water withdrawals. However, the magnitude of decline varied geographically. A “hot-spot” analysis was conducted based on predicted changes in FSR under each scenario to understand which HUC-12s were most likely to be affected by changes in water withdrawals, climate and impervious surfaces. Under the 20% withdrawal increase scenario, 413 of 886 (47%) HUC-12s in the study area were predicted to lose one or more species. HUC-12s in the Broad, Catawba, Yadkin and Cape Fear river basins were most susceptible to species loss. 4. These findings may help decision making efforts by identifying catchments most vulnerable to changing water availability. Additionally, FSR-discharge modeling results can assist resource agencies, water managers and stakeholders in assessing the effect of water withdrawals in catchments to better support the protection and long-term conservation of species.

Haines, B. 1983. Forest ecosystems SO4-S input-output discrepancies and acid rain: Are they related? Oikos 41: 139-143.

Abstract
The SO4-S inputs exceed SO4-S outputs in rain forests at San Carlos de Rio Negro, Amazonas, Venezuela and at La Selva, Costa Rica. Hypothesis to explain excess of inputs over outputs include (1) accumulation of S in biomass, (2) accumulation of S in soil, (3) conversion of SO4-S to organic S compounds which leave the system in drainage water, (4) conversion of SO4-S to volatile S compounds which leave as gases, and (5) estimation errors. Acid rain occurs at both sites. If the S were volatilized out of the forests, oxidized in the atmosphere to SO4, (4 above) then washed out of the atmosphere by rain, the resulting quantity of H2SO4 would be sufficient to account for the rainfall acidity observed in the field in Costa Rica.

Haines, B., J. Chapman, and C.D. Monk. 1985. Rates of mineral element leaching from leaves of nine plant species from a Southern Appalachian forest succession subjected to simulated acid rain. Bulletin of the Torrey Botanical Club 112(3): 258-264.

Abstract
Rates of mineral element leaching from plants subjected to simulated acid rain were determined for a forest succession including early successional herbs and a shrub-tree and six successional tree species. Simulated rain consisted of pH values of 5.5, 4.5, 3.5 and 2.5. Solutions were applied through a raindrop simulator at 0.9 cm/hr for 10 periods of 1 hr. each. Leachate from the leaves was analyzed for NH4-N, NO3-N, K, Ca, Mg, and P Rates of leaching ranged from 06 to 11.3 mg of element/10 dm2/hr. There were highly significant differences in leaching rates among species but no significant differences among pH treatments. Highest leaching rates occurred in the herbs. The absence of a pH effect on leaching rates is consistent with the absence of evidence of acid rain damage to the leaves of the plants tested.

Haines, B., M. Stefani, and F. Hendrix. 1980. Acid rain: threshold of leaf damage in eight plant species from a southern Appalachian forest succession. Water, Air and Soil Pollution 14: 403-407.

Abstract
Eight plant species were subjected to artificial acid rains of pH 2.5, 2.0, 1.5, 1.0, and 0.5 in order to determine the threshold for and symptoms of damage. The plants were Erechtites, Robinia, Pinus, Quercus, Carya, Liriodendron, Acer and Cornus from the Coweeta Hydrologic Laboratory. Droplets of pH 2.0 produced brown/necrotic spots on all species except Pinus, while droplets of pH 1.0 produced necroses on leaves of all species examined. The size of necrotic spots increased with increasing acidity. Results of this study suggest that a tenfold increase in acidity from pH 3.2 to 2.2 in a single spring or summer storm could bring damage or death to mature leaves of dominant flowering plants in the Southern Appalachians.

Haines, B.L. 1991. Identification and quantification of sulfur gases emitted from soils,leaf litter and live plant parts. Agriculture, Ecosystems and Environment 34: 473-477.

Abstract
Sulfur gas emission potentials can be quantified by incubating soil, leaf litter or plant parts in polypropylene centrifuge bottles, followed by analysis of accumulated head space gases with a gas chromatograph having a sulfur-specific flame photometric detector. Biological sulfur gas emissions can make a small contribution to atmospheric sulfur and to sulfuric acid rain. Sulfur gas emissions by plants are potentially significant as defenses against root rot fungi, nematodes and insects. Sulfur gas emissions which inhibit nitrification may function to conserve NH4 in the upper soil profile.

Haines, B.L., and G.R. Best. 1976. Glomus mosseae, endomycorrhizal with Liquidambar styraciflua L. seedlings retard NO3 and NH4 nitrogen loss from a temperate forest soil. Plant and Soil 45: 257-261.

Abstract
The influence of mycorrhizal fungus on downward movement of NH4, NO2, and NO3 nitrogen in forest soil was determined by establishing combinations of soil, fungus and seedlings in plastic pipes and monitoring the nitrogen content of water percolating to two depths. Compared with controls of soil alone and of soil + seedling alone, treatments containing the mycorrhizae showed a significant reduction of NH4-N loss from 5- and 25-cm depths and significant reduction of NO3-N loss from the 5-cm depth. No significant effect was observed on nitrite loss.

Haines, B.L., J.A. Jernstedt, and H.S. Neufeld. 1986. Direct foliar effects of simulated acid rain. II. Leaf surface characteristics. New Phytologist 99: 407-416.

Abstract
Surface characteristic and wettability of the leaves of six plant species have been examined in relation to their susceptibility to damage from simulated acid rain. The species examined differed in the type and extent of epicuticular wax deposits, surface topography of the cuticle, trichome type and distribution, and epidermal cell shape. Leaf wettability, as measured by either water-holding capacity on droplet contact angle, was significantly different among species, and is highly correlated with previous reports of damage from simulated acid rain. The leaves of Platanus occidetalis L. were the most wettable of the species examined and are reported to be damaged the most by repeated application of simulated acid rain. Mature leaves of Liriodendron tulipifera L., with high contact angles and very low water-holding capacity, are the least damaged according to published reports. Leaf water-holding capacity and surface- droplet contact angle may be useful first indicators of resistance to acid rain, and should be included in future studies of foliar effects of acid rain.

Haines, B.L., J.B. Waide, and R.L. Todd. 1982. Soil solution nutrient concentrations sampled with tension and zero-tension lysimeters: report of discrepancies. Soil Science Society of America Journal 46: 658-661.

Abstract
Four lysimeters were installed at each of 16 randomly designated locations. At each location, first at the litter-soil interface and again 30 cm beneath the litter-soil interface, one tension and one zero-tension lysimeter were installed side by side. Samples for 13 time intervals over a 15-month period were analyzed for water volume, H+, NH+4, K+, Na+, Ca2-, Mg2+, and NO-3, Cl-, SO2-4, H2PO4, and dissolved silica. Estimates of soil solution composition and water flow differed according to lysimeter type and sampling depth. A testable hypothesis is advanced to account for these observed discrepancies.

Hairston, N. G., Wiley, R. H., Smith, C. K. and Kneidel, K. A. (1992), THE DYNAMICS OF TWO HYBRID ZONES IN APPALACHIAN SALAMANDERS OF THE GENUS PLETHODON. Evolution, 46: 930-938. doi:10.1111/j.1558-5646.1992.tb00610.x

Abstract
Two zones of intergradation between populations of Plethodon have been studied for 18 and 20 years, respectively. The data consist of systematic scores of colors, made at least twice annually. Near Heintooga Overlook in the Balsam Mountains (Great Smoky Mountains National Park), the salamanders' cheeks are gray. Proceeding north toward the Smokies, there is increasing frequency and intensity of red color at two, four, and six miles. There has been no change in the scores at any location. The width of the zone and our failure to detect any change can be explained by assuming neutrality of the character and random diffusion during the probable time since contact between the two intergrading forms, which most likely took place after the Hypsithermal Interval, 8,000-5,000 BP. At Coweeta Hydrologic Laboratory in the Nantahala Mountains, Plethodon jordani and P. glutinosus hybridize at intermediate elevations. The lateral white spots of glutinosus decrease and the red on the legs of jordani increases with elevation from 685 m to 1,052 m. At the higher elevation, the proportion of animals scored as "pure" jordani declined significantly from 1974 to 1990, an indication that the hybrid zone is spreading upward. The rate of spread is too great to be explained by random diffusion, so selection for glutinosus characters is the best explanation. The rate of spread of the hybrid zone indicates that hybridization began 60-65 years ago, at the end of the time of intense timbering. Such human disturbances have caused hybridization in other organisms.

Hairston, N.G. 1973. Ecology, selection and systematics. Museum of Comparative Zoology, Cambridge, MA.

Abstract
Three different kinds of ecological relationships between newly separated species are examined, with the aim of establishing their expected effects on the systematic differences between the species involved. In cases of slight difference between the habitats of two products of recent speciation, selection can be expected to favor specific competitive mechanisms, but taxonomic differences would be expected to be slight, and examples of hybrid superiority would be common. Where the habitats of the two species are markedly different, as along a steep ecological gradient, adaptation to the different places will result in species that become broadly overlapping in habitat, and taxonomically different in many clearly adaptive characters. Although this latter process leads to species with somewhat different food habits, it would not lead to food specialization.

Hairston, N.G. 1980. Species packing in the salamander genus Desmognathus: what are the interspecific interactions involved? The American Naturalist 115(3): 354-366.

Abstract
The present paper presents evidence that questions previous interpretations and indicates that predation in and near streams has been more important than competition as the significant force in determining the evolution of the genus and the present structure of the community. The evidence consists of the size relationships, which are the reverse of what would be expected if competition had required increasing efficiency, the relative abundance of salamander predators in aquatic and terrestrial environments, and the failure of a majority of predictions about habitat shifts and size relationships when the predictions are based on the assumption of interspecific competition.

Hairston, N.G. Sr. 1986. Species packing in Desmognathus salamanders: experimental demonstration of predation and competition. The American Naturalist 127(3): 266-291.

Abstract
Salamanders have provided excellent material for ecological experiments. Long-lived animals with unusually stable populations, they conform to the implied assumptions embedded in theories of community organization and of evolution under the influence of interspecific interactions. Many species are abundant enough to provide ample material for experiments, and in some areas, expecially the southern Appalachians, multispecies associations among the family Plethodontidae are available for testing hypotheses about the organization of communities and the coevolution of their constituent species.

Hairston, N.G. Sr. 1993. On the validity of the name teyahalee as applied to a member of the Plethodon glutinosus complex (Caudata: Plethodontidae): a new name. Brimleyana. 18: 65-69.

Abstract
The name Plethodon teyahalee (Hairston) cannot be applied to the member of the P. glutinosus complex as designated by Highton (1983). Biochemical data show that the population from which the type of teyahelee was taken consists of hybrids between local populations representing the P. jordani and P. glutinosus complexes, and thus cannot be applied to a member of either of those two species under Article 23(h) of the International Code of Zoological Nomenclature (1985). A new name, Plethodon oconaluftee, is proposed, and a new type is designated.

Hairston, N.G. Sr., and R.H. Wiley. 1993. No decline in salamander (Amphibia: Caudata) populations: A twenty-year study in the Southern Appalachians. Brimleyana 18: 59-64.

Abstract
Identical observations, conducted 1-4 times per year for 15-20 years at two locations in the southern Appalachians, have yielded quantitative data on populations of six species of salamanders. Although the numbers have fluctuated for various reasons, there has been no trend in the numbers of any of the species. The world-wide decline of amphibian populations has not occurred in the two localities studied.

Hairston, N.G., R.H. Wiley, C.K. Smith, and K.A. Kneidel. 1992. The Dynamics of two hybrid zones in Appalachian salamanders of the genus Plethodon. Evolution. 46(4): 930-938.

Abstract
Two zones of intergradation between populations of Plethodon have been studied for 18 and 20 years, respectively. The data consist of systematic scores of colors, made at least twice annually. Near Heintooga Overlook in the Balsam Mountains (Great Smoky Mountains National Park), the salamanders' cheeks are gray. Proceeding north toward the Smokies, there is increasing frequency and intensity of red color at two, four, and six miles. There has been no change in the scores at any location. The width of the zone and our failure to detect any change can be explained by assuming neutrality of the character and random diffusion during the probable time since contact between the two intergrading forms, which most likely took place after the Hypsithermal Interval, 8,000-5,000 BP. At Coweeta Hydrologic Laboratory in the Nantahala Mountains, Plethodon jordani and P. glutinosus hybridize at intermediate elevations. The lateral white spots of glutinosus decrease and the red on the legs ofjordani increases with elevation from 685 m to 1,052 m. At the higher elevation, the proportion of animals scored as "pure" jordani declined significantly from 1974 to 1990, an indication that the hybrid zone is spreading upward. The rate of spread is too great to be explained by random diffusion, so selection for glutinosus characters is the best explanation. The rate of spread of the hybrid zone indicates that hybridization began 60-65 years ago, at the end of the time of intense timbering. Such human disturbances have caused hybridization in other organisms.

Hale, D.D., and J.W. Fitzgerald. 1990. Generation of sulphate from cysteine inforest soil and litter. Soil Biology and Biochemistry 22(3): 427-429.

Abstract
We have investigated cysteine transformation in forest floor layers and soil and have determined the effects of pH, substrate concentration and antimicrobial agents on the mineralization and immobilization of this amino acid.

Hales, T. C., and Miniat, C. F. (2017) Soil moisture causes dynamic adjustments to root reinforcement that reduce slope stability. Earth Surf. Process. Landforms, 42: 803–813. doi: 10.1002/esp.4039.

Abstract
In steep soil-mantled landscapes, the initiation of shallow landslides is strongly controlled by the distribution of vegetation, whose roots reinforce the soil. The magnitude of root reinforcement depends on the number, diameter distribution, orientation and the mechanical properties of roots that cross potential failure planes. Understanding how these properties vary in space and time in forests remains a significant challenge. Here we test the hypothesis that spatio-temporal variations in root reinforcement along a hillslope occur as a function of topographic soil moisture gradients. To test this hypothesis we compared root reinforcement measurements from relatively dry, divergent noses to relatively wet, convergent hollows in the southern Appalachian Mountains, North Carolina, USA. Our initial results showed that root reinforcement decreased in areas of higher soil moisture because the tensile strength of roots decreased. A post hoc laboratory experiment further demonstrated that root tensile strength decreased as root moisture content increased. This effect is consistent with other experiments on stem woods showing that increased water content in the cell wall decreases tensile strength. Our experimental data demonstrated that roots can adjust to changes in the external root moisture conditions within hours, suggesting that root moisture content will change over the timescale of large storm events (hours–days). We assessed the effects of the dynamic changes in root tensile strength to the magnitude of apparent cohesion within the infinite slope stability model. Slopes can be considerably less stable when precipitation-driven increases in saturated soil depth both increase pore pressures and decrease root reinforcement.

Hales, T., Ford, C., Hwang, T., Vose, J., Band, L. Topographic and ecologic controls on root reinforcement. Journal of Geophysical Research, 114: F03013

Abstract
Shallow landslides are a significant hazard in steep, soil-mantled landscapes. During intense rainfall events, the distribution of shallow landslides is controlled by variations in landscape gradient, the frictional and cohesive properties of soil and roots, and the subsurface hydrologic response. While gradients can be estimated from digital elevation models, information on soil and root properties remains sparse. We investigated whether geomorphically controlled variations in ecology affect the spatial distribution of root cohesion by measuring the distribution and tensile strength of roots from soil pits dug downslope of 15 native trees in the southern Appalachian Mountains, North Carolina, United States. Root tensile strengths from different hardwood tree species were similar and consistently higher than the only native shrub species measured (Rhododendron maximum). Roots were stronger in trees found on noses (areas of divergent topography) relative to those in hollows (unchanneled, convergent topography) coincident with the variability in cellulose content. This cellulose variability is likely related to topographic differences in soil water potential. For all species, roots were concentrated close to the soil surface, with roots in hollows being more evenly distributed in the soil column than those on noses. Trees located on noses had higher mean root cohesion than those in hollows because of a higher root tensile force. R. maximum had the shallowest, weakest roots suggesting that recent expansion of this species due to fire suppression has likely lowered the root cohesion of some hollows. Quantification of this feedback between physiologic controls on root growth and slope hydrology has allowed us to create a curvature-based model of root cohesion that is a significant improvement on current models that assume a spatially averaged value.

Hales, T.C., Scharer, K.M., Wooten, R.M., 2012. Southern Appalachian hillslope erosion rates measured by soil and detrital radiocarbon in hollows. Geomorphology 138:1, February 2012, p. 121–129, Elsevier

Abstract
Understanding the dynamics of sediment generation and transport on hillslopes provides important constraints on the rate of sediment output from orogenic systems. Hillslope sediment fluxes are recorded by organic material found in the deposits infilling unchanneled convergent topographic features called hollows. This study describes the first hollow infilling rates measured in the southern Appalachian Mountains. Infilling rates (and bedrock erosion rates) were calculated from the vertical distribution of radiocarbon ages at two sites in the Coweeta drainage basin, western North Carolina. At each site we dated paired charcoal and silt soil organic matter samples from five different horizons. Paired radiocarbon samples were used to bracket the age of the soil material in order to capture the range of complex soil forming processes and deposition within the hollows. These dates constrain hillslope erosion rates of between 0.051 and 0.111 mm yr-1. These rates are up to 4 times higher than spatially-averaged rates for the Southern Appalachian Mountains making creep processes one of the most efficient erosional mechanisms in this mountain range. Our hillslope erosion rates are consistent with those of forested mountain ranges in the western United States, suggesting that the mechanisms (dominantly tree throw) driving creep erosion in both the western United States and the Southern Appalachian Mountains are equally effective.

Hall, R.O. Jr. 1995. Use of stable carbon addition to trace bacterial carbon through a stream food web. Journal of The North American Benthological Society. 14(2): 269-277.

Abstract
The use of bacterial carbon by stream invertebrates was assessed by dripping 13C as sodium acetate into a headwater spring at Coweeta Hydrologic Laboratory for three weeks during August 1992. The addition raised the d13C value of dissolved organic carbon from approximately -26% to approximately 100%. Coarse particulate organic matter, fine particulate organic matter (FPOM), and 14 taxa of animals were analyzed by mass spectrometer before and after the 13C addition. Pre-addition sample d13C ranged from -36% to -22%, post-addition samples ranged from -35% to 129%. Predators contained less 13C label than collectors, shredders, and scrapers. Shredders were not uniformly labeled, suggesting low use of bacterial carbon. Stenonema (Heptageniidae), a biofilm scraper, was the most highly labeled taxon (up to 128%), even though biofilm d13C was -16%. Chironmomids and copepods were clearly labeled and had a higher d13C than the FPOM, suggesting preferential assimilation of bacterial carbon relative to FPOM. Although adults and larvae of Optioservus (Elmidae) are believed to be scrapers, the adults were more labeled than the larvae, indicating greater dependence on bacterial carbon. Gut analyses of Optioservus corroborated the stable isotope results: adult guts contained mostly detritus whereas larval guts contained a high proportion of diatoms. This technique is useful for determining the relative differences in bactivory by an assemblage of stream animals.

Hall, R.O. Jr., and J.L. Meyer. 1998. The trophic significance of bacteria in a detritus-based stream food web. Ecology. 79(6): 1995-2012.

Abstract
We compared relative use of streamwater dissolved organic carbon (DOC) by bacteria and the trophic significance of bacteria to invertebrates in tow headwater streams at Coweeta Hydrologic Laboratory in North Carolina: a stream with all leaf litter inputs excluded for 1 yr, and a reference stream. Leaf litter standing crop in the treatment stream was <1% that of the reference stream, and fine benthic organic matter (FBOM) was 50% lower than the reference. We used a whole-stream tracer addition of 13C-1 sodium acetate for 3 wk to label bacteria and hence their consumers during both July and December. Bacterial d13C was measured by collecting respired bacterial carbon. We estimated the contribution of bacterial carbon to consumers using a mixing model for invertebrates and bacteria. The acetate label declined exponentially downstream with a 10-m uptake length in each stream and season. FBOM and biofilm were the only detrital samples to show a strong label; both were more labeled in the litter-excluded stream. Bacteria in the litter excluded stream had 7-10 times more label than those in the reference stream during both seasons, showing their higher relative use of streamwater DOC. The percentage of invertebrate carbon derived from bacteria was >20% for many taxa. This was significantly related to the percentage of amorphous detritus in invertebrate guts, suggesting that bacterial carbon supporting higher trophic levels was asociated with amorphous detrital particles. Predatory invertebrates were labeled, showing that bacterial carbon was important for higher trophic levels. Some invertebrates were more highly labeled than the bacteria. Stenonema in the treatment stream contained eight times more label than measured bacteria. This suggests that they were using an unmeasured bacterial source such as bacteria in exposed epilithic biofilms, which had higher d13C than all other detrital components. Invertebrates in the treatment stream did not appear to use more bacterial carbon than in the reference stream despite a lower standing crop of detritus. Tallaperla, a shredding stonefly, derived 20-40% of its carbon from bacteria in both streams, even though it was more labeled in the treatment stream. Our estimates of the percentage of invertebrate carbon derived from bacteria were higher than those found in laboratory-based studies. To investigate reasons for this difference, we examined the possibility that bacterial carbon was principally found in exopolymers, as our labeling method would have labeled exopolymers. We found 6 g/m2 of colloidal carbohydrates in the reference stream, which was five times greater than bacterial biomass; thus the high use of bacterial carbon by invertebrates may be a consequence of the availability of these polymers.

Hall, R.O. Jr., B.J. Peterson, and J.L Meyer. 1998. Testing a nitrogen-cycling model of a forest stream by using a nitrogen-15 tracer addition. Ecosystems. 1: 283-298.

Abstract
Cycling of nitrogen (N) is commonly studied in aquatic ecosystems; however, most studies examine only parts of the N cycle, such as budgets, N uptake lengths, or oxidative transformations. To integrate conceptually and experimentally several aspects of the N cycle in a stream, we combined a N-cycling model and a tracer addition of nitrogen 15 (15N) to Hugh White Creek, a second-order forested mountain stream in North Carolina (USA). We calibrated a steady-state box model for N cycling in a 5-m stream segments that included dissolved, detrital, and biotic compartments. This model was parameterized based on prior studies and used to predict the expected distribution of tracer 15N in all compartments through both time and distance downstream of the addition site. We tested the model results with a 23-day continuous addition of 15N-NH4+ to the stream. Deviations of field data from model predictions suggested areas in which we lacked understanding of the N cycle. Downstream distribution of 15N in epilithon and moss matched model predictions, indicating that our prior estimations of N uptake rates were correct. Leaves and fine detritus contained less label than predicted by the model, yet their consumers had both higher d15N than predicted and higher d15N than the detritus itself, suggesting selective assimilation of microbial N from ingested detritus. Splitting fine benthic organic N (FBON) into a microbial and recalcitrant pool gave better predictions of FBON and seston d15N values relative to field data, yet overestimated invertebrate consumer d15N possibly because our estimates of the fraction of invertebrate N derived from microbes were too high. We predicted that much of the labeled N would move downstream via FBON suspension and transport. We found that most of the 15N remained near the addition site 33 days after the addition was stopped, suggesting that the stream is highly retentive of particulate N.

Hall, R.O. Jr., C.L. Peredney, and J.L. Meyer. 1996. The effect of invertebrate consumption on bacterial transport in a mountain stream. Limnology and Oceanography. 41(6): 1180-1187.

Abstract
Although laboratory studies have shown that filter-feeding invertebrates consume bacteria from stream water, no study has measured bacterial consumption in the field or determined system-level removal rates of sestonic bacteria. To examine bacterial removal rates and consumption by invertebrates, we released fluorescently labeled bacteria (FLB) in to a second-order stream at Coweeta Hydrologic Laboratory, North Carolina. We performed two 1-h releases during summer over bedrock habitat that supports many filter-feeders. We calculated uptake length and counted FLB in the guts of seven insect taxa. Uptake length was 78 and 83 m for the two releases, which corresponded to uptake rates of 4.03 and 3.69 X 107 cells m-2 min-1. Simulium, a filter-feeding blackfly larva, ingested FLB at a rate of 1.4 X 104 cells mg-1 min-1, 10 times the rate of other taxa. Diplectrona and Parapsyche, hydropsychid caddisfly filter-feeders, had ingestion rates between Simulium and other taxa. Epeorus, a scraping mayfly, and Tallaperla, a shredding stonefly, also ingested FLB, presumably from cells that adhered to the substrate. Invertebrate ingestion per square meter of stream bottom was 7% of total stream uptake, with Simulium responsible for 91% of the total invertebrate ingestion. Adhesion of FLB to the substrate from the water column seemed to be more important than invertebrate consumption in this stream, and one taxon, Simulium, was responsible for most invertebrate consumption of bacteria.

Hall, R.O. Jr., J.B. Wallace, and S.L. Eggert. 2000. Organic Matter Flow In Stream Food Webs With Reduced Detrital Resource Base. Ecology. 81(12): 3445-3463.

Abstract
Food webs based on flows of organic matter were developed for two small streams to examine food web response to a large reduction in detrital inputs. At the study site, Coweeta Hydrologic Laboratory in the southern Appalachians, leaf litter inputs and associated microbial assemblages are the main energy source for food webs in headwater streams. We eliminated leaf litter inputs to one stream using a net placed over the first 180 m of stream from its origin. Food webs based on flow of organic matter were developed for a referenced stream and the litter-excluded stream for two months, July and December of year 1 of the litter exclusion, to examine effects of leaf litter exclusion on the trophic base of the food web, size distribution of flows, predator-prey interactions and trophic structure. Flows (mg AFDM+m-2+d-1; AFDM = ash-free dry mass) were estimated using gut content analyses for detritus and prey items, coupled with secondary production estimates. We used a whole-stream 13C tracer method to estimate assimilation of bacteria by invertebrates. The food webs encompassed most (84-91%) of invertebrate secondary production, but <30% of the estimated total links. The primary sources of organic matter for the food web in the reference stream were leaf tissue, bacterial carbon, and animal prey, with ~25-30% of total secondary production derived from each. In-stream primary production led to <1% of invertebrate secondary production. A higher fraction of food web production in the litter-excluded stream was derived from wood. Magnitudes of detrital flows were lower in the litter-excluded stream, and some taxa were missing compared to the reference stream. The fraction of predator ingestion approached 100% of total secondary production of both streams, but this predation was distributed diffusely among several taxa. Flows to predators were fewer and smaller in the litter-excluded stream, yet these flows had higher per-biomass consumption coefficients, suggesting stronger interactions among the remaining common taxa. These food webs enabled us to examine interactions among taxa in the streams; hence, we found responses of the stream ecosystem ecosystem to litter-exclusion that we would not have considered had we only measured changes in invertebrate population sizes or system-level changes in organic matter flow.

Hall, R.O., et all. 2009. Nitrate removal in stream ecosystems measured by 15N addition experiments: Total uptake. Limnol. Oceanogr. 54(3): 653-665.

Abstract
We measured uptake length of 15NO{3 in 72 streams in eight regions across the United States and Puerto Rico to develop quantitative predictive models on controls of NO{3 uptake length. As part of the Lotic Intersite Nitrogen eXperiment II project, we chose nine streams in each region corresponding to natural (reference), suburban–urban, and agricultural land uses. Study streams spanned a range of human land use to maximize variation in NO{3 concentration, geomorphology, and metabolism. We tested a causal model predicting controls on NO{3 uptake length using structural equation modeling. The model included concomitant measurements of ecosystem metabolism, hydraulic parameters, and nitrogen concentration. We compared this structural equation model to multiple regression models which included additional biotic, catchment, and riparian variables. The structural equation model explained 79% of the variation in log uptake length (SWtot). Uptake length increased with specific discharge (Q/w) and increasing NO{3 concentrations, showing a loss in removal efficiency in streams with high NO{3 concentration. Uptake lengths shortened with increasing gross primary production, suggesting autotrophic assimilation dominated NO{3 removal. The fraction of catchment area as agriculture and suburban– urban land use weakly predicted NO{3 uptake in bivariate regression, and did improve prediction in a set of multiple regression models. Adding land use to the structural equation model showed that land use indirectly affected NO{3 uptake lengths via directly increasing both gross primary production and NO{3 concentration. Gross primary production shortened SWtot, while increasing NO{3 lengthened SWtot resulting in no net effect of land use on NO{3 removal.

Hannah, P.R. 1993. Composition and development of two Appalachian hardwood stands in North Carolina. The Journal of the Elisha Mitchell Scientific Society. 109(2): 87-98.

Abstract
Many events have shaped Appalachian forest structure and composition since the arrival of European settlers in the 1700s. Initially the forest was cleared for farming and adjacent woodlands burned annually for grazing. Mountain farms were ultimately abandoned and the invaded by forest. Extensive harvesting of remaining original and second growth forests began before 1900. Chestnut blight during the early 1900s caused further major changes. Harvesting and other land uses continue to shape the forest landscape today. Forests still dominate the more rugged sections of the region, and a few old and little-disturbed stands remain. Stand tally and stem analysis in Appalachian hardwood forests studied species composition, age structure, and height growth of existing trees. In a mature stand at Bent Creek the oldest trees, northern red oak and white oak, predate the 1870 land clearing. However, most trees became established between 1902 and 1915 after agricultural abandonment. In the early 1930s chestnut mortality opened the canopy for red maple, black birch, sourwood, black gum, and flowering dogwood. Present mortality is primarily black locust and black oak in the main canopy and flowering dogwood in the understory. Density of tree seedlings less than 2 m tall is low. The oldest trees are over 30 m tall but some established 60 years later are of equal height. At Coweeta, most trees became established after a heavy cut about 1920. Other trees entered the stand following the chestnut blight. Occasional large residual red oaks are dying, creating large gaps for a third age class. While considerable oak is in the main canopy, there is little oak regeneration. Composition may ultimately be dominated by sugar maple, white ash, yellow birch, and yellow buckeye. As these stands mature, gaps are likely to occur as a result of mortality of single trees or groups of trees. Stands will become more diverse in their age structure.

Hansen, R. A., and D.C. Coleman. 1998. Litter complexity and composition are determinants of the diversity and species composition of oribatid mites (Acari: Oribatida) in litterbags. Applied Soil Ecology. 9: 17-23.

Abstract
To investigate the relationship between litter complexity and composition and the diversity and composition of the oribatid mite fauna inhabiting it, an experiment was carried out at a single forested site in the mountains of North Carolina, USA. Natural litterfall was excluded from a series of 1 m2 plots and replaced with treatment litters that varied in composition and complexity. Plots of pure birch, maple and oak litter comprised the simple litter treatments. Two complex litters were made of a mixture of these three litter species and a mixture of seven litter species. Treatment litters were applied to the plots in the autumn of 1993 and again in 1994. The oribatid mites extracted from litterbags of the treatment litters from both years are reported on here. Mixed litters had a significantly greater variety of microhabitats, as defined by substrate type and fungal growth form, than did the simple litters. Likewise, the oribatid mite species richness in litterbags of mixed liter was significantly higher than that in the simple litters. The fauna within replicates of each litter-type were more similar to each other than to those of other treatments. A third of the mite species tested showed a differential response among the simple litter-types. These results indicate a link between heterogeneity and diversity of mites active in a particular horizon of litter and some influence of litter-type upon species composition. Such patterns in habitat use by adult mites are strong, though not conclusive evidence of the ultimate role of heterogeneity in maintaining the diversity of oribatid mites.

Hansen, R.A. 1999. Red oak litter promotes a microarthropod functional group that accelerates its decomposition. Plant and Soil. 209: 37-45.

Abstract
The contribution of microarthropod activity to litter decomposition varies widely but can be substantial. Oribatid mites are the most diverse and abundant of the microarthropod groups in forest litter. This experiment was designed to examine the effect of litter type and complexity on the diversity and species composition of oribatid mites, and to test whether alterations in species composition due to litter type affected litter decomposition. In an array of plots on a mixed-hardwood site in the mountains of North Carolina, I exposed microarthropod assemblages to a range of litter types: yellow birch, sugar maple, red oak and two mixed litters. Over several years, the litter types selected oribatid mite assemblage of different species composition. By comparing the decomposition of consecutive cohorts of litter, it was possible to detect differences in decomposition accompanying the shifts in the assemblage. A comparison of the mass loss rates between the two litter cohorts over eighteen months reveals similar trajectories for four litter types. In the oak litter, however, the second cohort disappeared significantly faster than the first. In both years, the litters came from the same trees and were nearly identical in initial carbon and nitrogen contents. Since the response was specific to oak litter, it is unlikely that differences in environmental factors are responsible for the faster mass loss of oak. A significant increase of endophagous oribatid mites, those that burrow into plant material, in the second cohort of oak may account for its accelerated decomposition. The woody petioles and thick leaf-planes of oak leaves provide microhabitats for burrowing mites. Endophage activity can accelerate the litter decomposition both through direct comminution of leaf material and by facilitating microbial growth. Because of their low population growth rates, oribatid populations that are reduced by disturbance are slow to recover and by disrupting these non-resilient populations, disturbance may have long-term repercussions for decomposition.

Hansen, R.A. 2000. Effects Of Habitat Complexity And Composition On A Diverse Litter Microarthropod Assemblage. Ecology. 81(4): 1120-1132.

Abstract
Oribatid mites (Acari: Oribatida) are the most diverse arthropod group in forest litter and soil, and they make significant contributions to decomposition as microbial grazers and saprophages. As is true for all the hyperdiverse soil taxa, the determinants of their diversity and species composition are virtually unexplored. The experiment tests whether heterogeneity of the litter habitat is a determinant of their local diversity, and whether litter composition is a determinant of their species composition. At a single site of temperate deciduous forest at the Coweeta Hydrological Laboratory in the mountains of North Carolina, USA, natural litterfall was excluded from a series of 42 1-m+ plots and, for three consecutive years, replaced with treatment litters that varied in their composition and complexity. Plots of pure yellow birch (Betula alleghaniensis), sugar maple (Acer saccharum), and red oak (Quercus rubra) litter comprised the monotypic or simple litter treatments. Two complex litters included a mixture of these three litter species and a mixture of seven litter species with pieces of small woody debris.Monotypic litters developed profiles of reduced thickness that contained lower numbers of invading roots and less humic and arthropod fecal material. Over 3 yr, oribatid abundance and , though the dominant species, Oppiella nova, was unaffected by litter simplification. Similarity of species composition increased markedly among replicates within each litter treatment for two sectors of the assemblage: the large, litter-dwelling species and the endophagous and wood-associated species. Species composition among small litter-dwellers was unresponsive to litter type. Several characteristics of monotypic-litter habitats potentially contributed to the erosion of the oribatid assemblage. Loss of structure in monotypic litter likely led to reduced and less hospitable physical living space. It appeared to reduce recruitment of roots and retention of humic and fecal material in the litter layer. Each monotypic litter contained only a subset of the structural microhabitats that serve as refugia for eggs and juveniles. Finally, the synchronized decomposition of uniform substrates could have led to a boom-bust economy in microbial resources that was unfavorable to oribatid mites and their conservative life histories.

Harding, J.S., E.F. Benfield, P.V. Bolstad, G.S. Helfman, and E.B.D Jones III. 1998. Stream biodiversity: The ghost of land use past. Proceedings of the National Academy of Sciences of the United States of America. 95: 14843-14847.

Abstract
The influence of past land use on the present-day diversity of stream invertebrates and fish was investigated by comparing watersheds with different land-use history. Whole watershed land use in the 1950s was the best predictor of present-day diversity, whereas riparian land use and watershed land use in the 1990s were comparatively poor indicators. Our findings indicate that past land-use activity, particularly agriculture, may result in long-term modifications to and reductions in aquatic diversity, regardless of reforestation of riparian zones. Preservation of habitat fragments may not be sufficient to maintain natural diversity in streams, and maintenance of such biodiversity may require conservation of much or all of the watershed.

Hardt, R.A., and W.T. Swank. 1997. A comparison of structural and compositional characteristics of Southern Appalachian young second-growth, maturing second-growth, and old-growth stands. Natural Areas Journal. 17(1): 42-52.

Abstract
Forest stand structural and compositional characteristics were studied in two stands each of Southern Appalachian old growth, maturing second growth (previously selectively logged), and young second growth (previously clearcut) to determine differences among these stands. Mature second growth and young second growth represent common stand conditions in this region. Tree species diversity was highest in maturing second-growth, intermediate in old-growth, and lowest in young second-growth stands. Old-growth stands had an overstory tree composition of a mix of shade-intolerant and intermediate species; maturing second-growth overstories were dominated by intermediate species; young second-growth overstories were dominated by shade-intolerant species. Densities of large live trees, trees with cavities, and snags were highest in old-growth stands and lowest in young second-growth stands. Log accumulations were highest in one young second-growth stand and lowest in another young second-growth stand that had been clearcut twice. Log accumulations in old-growth stands were higher than in maturing second-growth stands. Maturing second-growth stands were more similar in structural characteristics to the old-growth stands than to the young second-growth stands. Stand history appears to have highly influenced many structural and compositional characteristics. Although the sample size was small, the old-growth stands have several characteristics that developed as a result of their undisturbed history; these characteristics should be considered during planning for future old growth on Southern Appalachian national forests.

Hargrove, W.W. 1986. An annotated species list of insect herbivores commonly associated with Black Locust, Robinia pseudo-acacia, in the Southern Appalachians. Entomological News 97(1): 36-40.

Abstract
An annotated species list is presented as an aid to identification of phytophagous insects found on black locust, Robinia pseudo-acacia, in the Southern Appalachians. The list, containing 75 species, is annotated regarding host preference, presence in Southern Appalachians, abundance, and host specificity.

Hargrove, W.W. 1987. A video digitizer for the rapid measurement of leaf area removed by herbivorous insects. Technological tools section, Bull. Ecol. Soc. Amer. 68(2): 185.

Abstract
None

Hargrove, W.W. 1988. A photographic technique for tracking herbivory on individual leaves through time. Ecological Entomology 13: 359-363.

Abstract
Accurate measurement of leaf area removed (LAR) by chewing insect herbivores is used to evaluate progress in insect control, plant breeding, and genetic screening and engineering programs, and to assess impacts of herbivores on ecosystem function. End-of-season estimates of LAR may underestimate herbivory because of hole growth with leaf expansion and consumption of entire leaves. This report describes a method using photographic proof paper for following herbivory through time, yielding more accurate estimates and indicating the seasonal dynamics of herbivory.

Hargrove, W.W., and D.A. Crossley Jr. 1988. Video digitizer for the rapid measurement of leaf area lost to herbivorous insects. Annals of the Entomological Society of America 81(4): 593-598.

Abstract
An IBM PC or compatible microcomputer equipped with a Tekmatic Systems Video Van Gogh digitizer card can be interfaced with a standard video camera for rapidly measuring the percentage of leaf area lost (LAL) to herbivorous insects. This capability can be added to an existing color PC for about 600. The system digitizes a video image of a reconstructed leaf and displays the amount of LAL in about 20 s. The video digitizer simultaneously measures area removed from, and area remaining in, the leaf without tracing of these areas by the operator, greatly increasing the number of leaves that can be measured. Digitized measurements are saved to a sequential ASCII data file compatible with database, spreadsheet, and word processor programs. The video digitizer software allows two video camera work stations to be supported by a single computer. Software for the video digitizer is in the public domain and can be obtained from the authors.

Hargrove, W.W., and J.R. O'Hop Jr. 1988. A Computer Algorithm to Estimate Leaf Area Removal (LAR) by Insects. Laboratory Microcomputer. 7(1): 36-40.

Abstract
A computer algorithm is described which can be used with a magnetic planimeter board to produce a rapid and accurate digital planimeter. A version for the measurement of percentage of leaf area removal (LAR) by chewing phytophagous insects is given using the Hewlett-Packard* HP 9825A computer system as an example, although the algorithm has wide ecological applicability and is compatible with many small computer systems. An area algorithm using polar rather than rectangular coordinates economizes on the storage of intermediate points, allowing measurement of closed areas of any size or shape. Sensitive areas are set up on the digitizer surface to allow the user to concentrate on measurements instead of switching attention between digitizer and keyboard. Correction routines allow for removal of errors and preservation of statistical intermediates. Data collection, transformation, storage and initial statistical analysis are performed during the measurement step. Estimation error is less than 1.2% when measuring actual areas of 25 cm or less.

Hargrove, W.W., D.A. Crossley Jr., and T.R. Seastedt. 1984. Shifts in insect herbivory in the canopy of black locust, Robinia pseudo-acacia, after fertilization. Oikos 43: 322-328.

Abstract
Black locust trees fertilized with N, P, and K initially incurred higher losses to chewing insects, but subsequently gained some protection from herbivory. This protection consisted of two distinct tactics: (1) a tolerance response, in which greater photosynthetic area was produced, and (2) a resistance response, in which insect preference shifted to foliage of non-fertilized trees. Consumption damage accrued in the foliage of control trees in a linear fashion throughout the season. Relative concentrations of five major macronutrients were statistically the same or greater in foliage of fertilized trees than in controls from mid-June through August. A small secondary leaf flush was observed exclusively in fertilized trees.

Harper, C.A, and D.C. Guynn Jr. 1999. Factors affecting salamander density and distribution within four forest types in the Southern Appalachian Mountains. Forest Ecology and Management. 114: 245-252.

Abstract
We used a terrestrial vacuum to sample known area plots in order to obtain density estimates of salamanders and their primary prey, invertebrates of the forest floor. We sampled leaf litter and measured various vegetative and topographic parameters within four forest types (oak-pine, oak-hickory, mixed mesophytic and northern hardwoods) and three age classes (0-12, 13-39, and + 40-years) over two field seasons within the Wine Spring Creek Ecosystem Management area in western North Carolina.

Harper, C.A., and D.C. Guynn Jr. 1998. A terrestrial vacuum sampler for macroinvertebrates. Wildlife Society Bulletin. 26(2): 302-306.

Abstract
Macoinvertebrate abundance and biomass is an important consideration when managing upland game birds. Although several techniques have been employed sampling macroinvertebrate communities, the advantages of sampling with a vacuum sampler are discussed. Instructions are given on modifying a blower/vac into a vacuum sampler for macroinvertebrates. Cost efficiency, ease of use and increased mobility make this vacuum sampler more attractive than the D-vac sampler. Potential value as a sampling tool for other ecological data, such as salamander density and mast abundance, make this sampler a useful tool for a variety of sampling situations.

Harper, V.L. 1953. Watershed Management: Forest and Range Aspects in the United States. Unasylva. 7(3): 105-114.

Abstract
The importance of water management in the economy of the United States is being recognized to an increasing degree. Very large investments in engineering works to control and utilize water have been made, and even larger works are being planned. However, the effects of vegetative cover and soil-mantle conditions on watersheds and thereby on stream regimen have also been recognized in a long series of laws relating to forest, range, and open lands, and substantial accomplishments in the protection and improvement of watershed lands have already been made through measures adopted primarily for other purposes. In large areas, however, these measures have still not been adequate to give the needed projection and improvement. Specialized research on watershed management problems, particularly those relating to the effects of land use practices on water yields, has been underway but, so far, on a very modest scale. A considerable body of technical knowledge has been developed and more will be forthcoming as greater public awareness of the need for such knowledge continues to develop. Several outstanding examples of successful rehabilitation of badly-damaged watersheds are now at hand. These, however, are only a scratch on the surface of a very large task that remains to be done.

Harshbarger, T.J. 1979. Scraping improves silver nitrate brands on trout. Progressive Fish-Culturist 41: 209.

Abstract
A device for scraping mucosal material and scales from fish prior to branding with silver nitrate is described. Improved brands are obtained using this technique.

Harshbarger, T.J. 1984. Living trout mean living water. Katuah 4: 3, 22.

Abstract
This nontechnical survey of the impacts of land use upon mountain trout waters was published in newspaper format.

Harshbarger, T.J., and P.E. Porter. 1979. Survival of brown trout eggs: two planting techniques compared. Progressive Fish-Culturist 41: 206-209.

Abstract
This paper compares survival of eggs, embryos, and swim-up fry of brown trout (Salmo trutta) in direct intragravel plants and in Vibert boxes. Egg mortality increased disproportionately in Vibert boxes after 4 weeks until time of hatching. Direct intragravel plants yielded the highest survival to the swim-up stage.

Harshbarger, T.J., and P.E. Porter. 1982. Embryo survival and fry emergence from artificially planted trout eggs: two techniques compared. North American Journal of Fisheries Management 2: 84-89.

Abstract
Survival of larval trout through the swim-up stage was determined for eyed eggs of brown trout (Salmo trutta) planted both in the streambed and in Whitlock Vibert boxes. Direct plants produced 2 times more sac fry than box plants and 3.5 times more swim-up fry. Sediment deposition was approximately 100 percent greater in first- and second-order streams than in third-order streams, and sediments accumulated disproportionately in box plants. This seemed to account for survival differences between planting techniques and among stream orders.

Harshbarger, T.J., C.J. Perkins, and R.E. Martin. 1975. Legume response unrelated to fuel moisture at time of burning. Journal of Range Management 28: 70-71.

Abstract
The response of sensitive partridgepea and other legumes was unrelated to moisture content of fuels at the time a slash pine stand was burned.

Hartman, M.D., Baron, J.S., Ewing, H.A. and Weathers, K.C. 2014. Combined global change effects on ecosystem processes in nine U.S. topographically complex areas. Biogeochemistry. (DOI: 10.1007/s10533-014-9950-9.)

Abstract
Concurrent changes in climate, atmospheric nitrogen (N) deposition, and increasing levels of atmospheric carbon dioxide (CO2) affect ecosystems in complex ways. The DayCent-Chem model was used to investigate the combined effects of these human-caused drivers of change over the period 1980–2075 at seven forested montane and two alpine watersheds in the United States. Net ecosystem production (NEP) increased linearly with increasing N deposition for six out of seven forested watersheds; warming directly increased NEP at only two of these sites. Warming reduced soil organic carbon storage at all sites by increasing heterotrophic respiration. At most sites, warming together with high N deposition increased nitrous oxide (N2O) emissions enough to negate the greenhouse benefit of soil carbon sequestration alone, though there was a net greenhouse gas sink across nearly all sites mainly due to the effect of CO2 fertilization and associated sequestration by plants. Over the simulation period, an increase in atmospheric CO2 from 350 to 600 ppm was the main driver of change in net ecosystem greenhouse gas sequestration at all forested sites and one of two alpine sites, but an additional increase in CO2 from 600 to 760 ppm produced smaller effects. Warming either increased or decreased net greenhouse gas sequestration, depending on the site. The N contribution to net ecosystem greenhouse gas sequestration averaged across forest sites was only 5–7 % and was negligible for the alpine. Stream nitrate (NO3 −) fluxes increased sharply with N-loading, primarily at three watersheds where initial N deposition values were high relative to terrestrial N uptake capacity. The simulated results displayed fewer synergistic responses to warming, N-loading, and CO2 fertilization than expected. Overall, simulations with DayCent-Chem suggest individual site characteristics and historical patterns of N deposition are important determinants of forest or alpine ecosystem responses to global change.

Hatcher, R.D. Jr. 1979. The Coweeta Group and Coweeta syncline: major features of the North Carolina - Georgia Blue Ridge. Southeastern Geology 21(1): 17-29.

Abstract
The name Coweeta Group is proposed for a group of metasedimentary and possible metaigneous rocks which occur in the east-central Blue Ridge of North Carolina and Georgia and overlie the rocks of the Tallulah Falls Formation. The group is composed of three formations. The oldest is the Persimmon Creek Gneiss. This is overlain by the Coleman River Formation, then the Ridgepole Mountain Formation. The age of the Coweeta Group is uncertain. The Coweeta syncline results from a history of polyphase deformation. It appears to be overturned toward the east, and the west limb is cut off by the Shope Fork fault.

Hawman, R. B. 2007. Crustal thickness variations across the Blue Ridge Mountains, southern Appalachians: An alternative procedure for migrating wide-angle reflection data. Bulletin of the Seismological Society of America. 98(1): 469-475.

Abstract
Migration of wide-angle reflections generated by quarry blasts suggests that crustal thickness increases from 38 km beneath the Carolina Terrane to 47-51 km along the southeastern flank of the Blue Ridge. The migration algorithm, developed for generating single-fold images from explosions and earthquakes recorded with isolated, short-aperture arrays, uses the localized slant stack as an intermediate data set. In contrast with other methods, it includes an interpretive step that is based on the assumption that all coherent P-wave energy consists of reflections from planar interfaces. Each sample in the slant stack is mapped into a planar, dipping segment with a length that is determined by the recording aperture. Migrated sections from within the Blue Ridge show increases in reflectivity at depths of 20 and 40 km. High apparent reflectivity from 40 to 50-55 km suggests a layered zone in the lower crust which is similar to models proposed for the Cumberland Plateau in Tennessee and the Adirondacks. The migration results are consistent with regional gravity data and with the occurrence of crustal roots beneath the Urals, another Paleozoic orogen.

Hawthorne S, Miniat CF. Topography may mitigate drought effects on vegetation along a hillslope gradient. Ecohydrology. 2017;e1825. https://doi.org/10.1002/eco.1825

Abstract
Topography may mitigate drought effects on vegetation along a hillslope gradient through redistribution of soil moisture. We examined the interaction of topography, climate, soil moisture, and transpiration in a low-elevation, mixed-hardwood forest in the southern Appalachian Mountains. The effects of meteorological variation (wet and dry years) and topographic position (upslope and cove) were tested on daily soil moisture amplitude and recession and plot and species-specific transpiration. Trees in the cove plot were 17% taller and had 45% greater sapwood area than those in the upslope plot. Lower rates of soil moisture recession following rainfall events were observed at the cove plot compared to the upper plot. Greater daily soil moisture amplitude and plot transpiration, even in dry years, suggest that lower slope positions may have been buffered against moderate drought. We also observed similar transpiration in Quercus spp., Carya spp., and Liriodendron tulipifera in the cove plot between dry and wet years. Plot transpiration was reduced by 51% in the dry year in the upslope plot only, and transpiration by individual species in the plot reflected this pattern, suggesting water stress in dry years may be exacerbated by topography. With drought predicted to increase for these systems, the different drought responses of species, in addition to topographic effects, may lead to complex shifts in species composition.

Hazelton, P.D., Grossman, G.D. 2009. The effects of turbidity and an invasive species on foraging success of rosyside dace (Clinostomus funduloides). Freshwater Biology, 54: 1977-1989

Abstract
1. Habitat degradation and biological invasions are important threats to fish diversity worldwide. We experimentally examined the effects of turbidity, velocity and intra- and interspecific competition on prey capture location, reactive distance and prey capture success of native rosyside dace (Clinostomus funduloides) and invasive yellowfin shiners (Notropis lutipinnis) in Coweeta Creek, North Carolina, U.S.A. 2. Increased turbidity and velocity produced significant decreases in the number of prey captured forward of the fish’s location. It is possible that this represents an increase in the amount of energy expended per prey captured. 3. We used Akaike’s Information Criterion (AIC) to evaluate competing explanatory models for reactive distance (10 generalised linear models, GLM) and prey capture success (9 generalised linear mixed models, GLMM). 4. Reactive distance decreased by 12% with an increase from 2 to 4 conspecifics, whereas a 10 NTU increase in turbidity reduced reactive distance by 9%. Capture success was affected by velocity, dominance and competition, and varied among species. A 6 cm s)1 increase in velocity produced a 28% decline in capture probability; however, dominant fish were 3.2 times more likely to capture a prey item than non-dominant fish. Yellowfin shiners only were 0.62 times as likely to capture a prey item as rosyside dace. Both intraand interspecific competition reduced capture probability, and fish in high density intraspecific or interspecific trials were 0.46 times and 0.44 times as likely to capture prey, respectively, as fish in two fish intraspecific trials. 5. These results suggest behavioural variables are as important as physical factors in determining reactive distance and capture probability by these minnows.

Hazelton, P.D., Grossman, G.D. 2009. Turbidity, velocity and interspecific interactions affect foraging behaviour of rosyside dace (Clinostomus funduloides) and yellowfin shiners (Notropis lutippinis). Ecology of Freshwater Fish, 18:427-436

Abstract
Fish diversity is strongly affected by habitat degradation (e.g., increased turbidity) and invasive species. We examined the effects of turbidity, velocity, length, dominance and intra- and interspecific competition on focal point depth, movement rate, dominance and aggression rate in native rosyside dace (Clinostomus funduloides) and invasive yellowfin shiners (Notropis lutipinnis) in a southern Appalachian stream (NC, USA). We compared results for intra- and interspecific groups of fishes at two densities (two and four fishes), three turbidity levels (10, 20 and 30 nephelometric turbidity units), and two velocities (12, 18 cms-1). Dominance was significantly correlated with length in intraspecific groups of both species, and dominant fish held more profitable foraging positions about 75% of the time. Yellowfin shiners were dominant more often than rosyside dace in interspecific trials. Akaike’s Information Criterion indicated that models containing turbidity, velocity, species and intraspecific competition, explained the greatest amount of information in focal point depth data. By contrast, movement and aggression rates were best explained by models based on dominance and velocity. Finally, aggression rate was best explained by models containing fish length and turbidity. These results indicate that habitat degradation, intra- and interspecific interactions influence the foraging behaviour and future success of these species in the Little Tennessee River drainage.

Hedman, C.W., and D.H. Van Lear. 1995. Vegetative structure and composition of Southern Appalachian riparian forest. Bulletin of the Torrey Botanical Club 122(2): 134-144.

Abstract
Vegetative characteristics of twelve Southern Appalachian riparian forests were sampled as part of a larger study which examined functional attributes of riparian zones. Riparian forests were representative of the mixed mesophytic forest, eastern hemlock forest, and transitions between these types. Early- and mid-successional stages were generally dominated by shade-tolerant species and had an even-aged structure. The diameter distribution of these relatively young stands of mixed species was typically inverse J-shaped. Late-successional and old-growth stages were dominated by an overstory of pioneering shade-intolerant or moderately tolerant overstory species and were uneven-aged. Diameter distribution in these older stands approximated a rotated sigmoid curve. Rhododendron (Rhododendron maximum L.) was the dominant understory species and controlled understory and midstory composition. Characterization of riparian forests in different stages of succession will help understanding of vegetative processes and forms the basis of subsequent ecological studies of riparian functional dynamics.

Hedman, C.W., D.H. Van Lear, and W.T. Swank. 1996. In-stream large woody debris loading and riparian forest seral stage associations in the southern Appalachian Mountains. Canadian Journal of Forest Research 26: 1218-1227.

Abstract
Large woody debris (LWD) is an important ecological component of mountain streams. However, the relation of LWD loading and riparian forest composition is poorly understood in the southern Appalachians. In this study, 500-m reaches of 11 riparian forest-stream systems representing a 300-year sere were inventoried and measured to obtain quantitative estimates and descriptions of in-stream LWD. Loading volumes ranged from 7.1 to 31.2 m3/100 m of stream, or between 3.6 and 13.2 kg/m2. LWD loadings were highly variable during midseral stages of plant community succession, primarily because of the wide range in loading of American chestnut. Loadings increased linearly in late-successional through old-growth systems over a 165-year interval. Eastern hemlock and American chestnut were the most dominant carry-over LWD species in midsuccessional stream systems. Loading of eastern hemlock LWD increased from midsuccessional through old-growth stages as the species became dominant in the riparian forest. Without carry-over debris, LWD loadings would be extremely low in midsuccessional stream systems. American chestnut was a major component of LWD in midsuccessional stream systems, despite the fact that it has been unavailable for recruitment for decades.

Helton, A.M., G.C. Poole, J.L. Meyer, W.L. Wollheim, B.J. Peterson, P.J. Mulholland, E.S. B ernhardt, J.A. Stanford, C. Arango, L.R. Ashkenas, L.W. Cooper, W.K. Dodds, S.V. Gregory, R.O. Hall, S.K. Hamilton, S.L. Johnson, W.H. McDowell, J.D. Potter, J.L. Tank, S.M. Thomas, H.M. Valett, J.R. Webster, and L. Zeglin. 2010. Thinking outside the channel: Nitrogen cycling in networked river ecosystems. Frontiers in Ecology and the Environment 9(4):229-238.

Abstract
Agricultural and urban development alters nitrogen and other biogeochemical cycles in rivers worldwide. Because such biogeochemical processes cannot be measured empirically across whole river networks, simula- tion models are critical tools for understanding river-network biogeochemistry. However, limitations inherent in current models restrict our ability to simulate biogeochemical dynamics among diverse river networks. We illustrate these limitations using a river-network model to scale up in situ measures of nitrogen cycling in eight catchments spanning various geophysical and land-use conditions. Our model results provide evidence that catchment characteristics typically excluded from models may control river-network biogeochemistry. Based on our findings, we identify important components of a revised strategy for simulating biogeochemical dynamics in river networks, including approaches to modeling terrestrial–aquatic linkages, hydrologic exchanges between the channel, floodplain/riparian complex, and subsurface waters, and interactions between coupled biogeochemical cycles.

Helvey, J D. 1967. Interception by eastern white pine. Water Resources Research 3: 723-729.

Abstract
Measurements taken in a 10-, a 35-, and a 60-year-old stand of eastern white pine in the southern Appalachians of western North Carolina were used to derive regression equations for estimating throughfall, stemflow, and the sum of throughfall and stemflow from measurements of gross rainfall. Equations for total interception loss were derived and used to predict total seasonal interception loss (I) from measurements of total seasonal rainfall ( P) and number of storms (N). For the 10-year-old stand, I = 0.05(N) + 0.08( P); for the 35-year-old stand, I = 0.05(N) + 0.12 ( P); and for the 60-year-old stand, I = 0.06(N) + 0.18( P). Total interception loss in white pine increased with stand age, and total loss from all pine stands studied exceeded losses calculated for mature hardwoods.

Helvey, J.D., and J.D. Hewlett. 1962. The annual range of soil moisture under high rainfall in the Southern Appalachians. Journal of Forestry 60: 485-486.

Abstract
Observations of soil moisture at Coweeta suggest that forest vegetation at this Laboratory rarely, if ever, suffers true drought. Seasonal changes in soil moisture were strongly correlated with changes in streamflow.

Helvey, J.D., and J.H. Patric. 1965. Canopy and litter interception of rainfall by hardwoods of eastern United States. Water Resources Research 1: 193-206.

Abstract
Results from all available studies of rainfall interception by hardwoods of the Eastern United States vary over a small range. Data from past studies were used to develop regression equations describing the relation between gross rainfall, throughfall, and stemflow for eastern hardwood forests during the growing and dormant seasons.

Henderson, G.S., W.T. Swank, J.B. Waide, and C.C. Grier. 1978. Nutrient budgets of Appalachian and Cascade region watersheds: a comparison. Forest Science 24: 385-397.

Abstract
Precipitation inputs and streamflow outputs of nitrogen, calcium, potassium, magnesium, and sodium were compared for two deciduous forest watersheds and a coniferous forest watershed. While nitrogen inputs varied by nearly tenfold among the watersheds, ammonium and nitrate discharge in streamflow was uniformly small resulting in net accumulation within all three ecosystems. In contrast, cation discharge was more variable among the watersheds than cation input and was strongly related to the bedrock of each watershed. The internal distribution and cycling of nitrogen, potassium, and calcium within each of the three watershed ecosystems were also compared. There were interpretable differences between nutrient cycling patterns in the coniferous and deciduous forests. Overall, however, all three ecosystems were effectively retaining and recycling these nutrients.

Hendrixson, B.E., and J.E. Bond. 2005. Testing species boundaries in the Antrodiaetus unicolor complex (Araneae: Mygalomorphae: Antrodiaetidae): (Paraphyly and cryptic diversity. Molecular Phylogenetics and Evolution. 35: 405-416.

Abstract
The inability to correctly identify species has far reaching implications in nearly all areas of biology, yet few studies investigate methods for delineating species boundaries. Moreover, once these boundaries have been hypothesized, little thought has been given to how these constructs can be further evaluated. We employ a molecular phylogenetic approach using nuclear 28S rRNA and mitochondrial cytochrome c oxidase subunit I genes to test the general eYcacy of species boundaries in the Antrodiaetus unicolor spider species complex. Our analyses provide evidence that An. unicolor is (paraphyletic  with respect to An. microunicolor, indicating that morphological criteria used to delineate species boundaries undersplits actual species-level diversity in this group of spiders. These analyses also demonstrate that individuals from geographically proximate populations sometimes exhibit considerable molecular divergence, strongly suggesting that An. unicolor is a cryptic species complex. Finally, this molecular approach has provided the phylogenetic framework that is necessary to begin interpreting the vast amount of morphological variation observed in these spiders based upon Wndings from previous studies. Our approach using multiple genes appears to be a rigorous method to critically examine species boundaries originally based on traditional morphological approaches to spider taxonomy.

Hendrixson, B.E., and J.E. Bond. 2005. Two sympatric species of Antrodiaetus from southwestern North Carolina (Araneae, Mygalomorphae, Antrodiaetidae). Zootaxa. 872: 1-19.

Abstract
Two sympatric species of Antrodiaetus (Araneae, Mygalomorphae, Antrodiaetidae) are recorded from southwestern North Carolina: A. unicolor (Hentz 1841) and A. microunicolor new species. A neotype for A. unicolor is designated from DeSoto State Park in Alabama and a description is provided. A new species of Antrodiaetus is described from the Coweeta Long Term Ecological Research station in southwestern North Carolina. This new species is sympatric (putatively syntopic) with the closely related A. unicolor and can be differentiated from that species on the basis of size, setal characters, coloration, selected morphometric ratios, and non-overlapping breeding seasons. A brief account on the natural history for both species at Coweeta is presented.

Heneghan, L., A. Salmore, D.A. Crossley Jr. 2004. Recovery of decomposition and soil microarthropod communities in an Appalachian watershed two decades after a clearcut. Forest Ecology and Management. 189: 353-362.

Abstract
We examined decomposition rates of three substrates (Quercus prinus L., Acer rubrum L., and Cornus florida L.) in a watershed 21 years after it had been clearcut, and compared them to an adjacent control watershed. Previous investigations at these sites had shown that microarthropod populations, important components of the decomposer community, were considerably less dense in the clearcut watershed and that decomposition rates were reduced. Twenty-one years after clearcut decomposition rates in the clearcut watershed had reconverged with the control, and in the case of one substrate (C. florida) now exceeded the control. Microarthropods maintained denser populations in the clearcut watershed, and oribatid assemblages, the most abundant taxonomic group, were more diverse in that watershed. A contrast of the decomposition of the substrates 8 and 21 years after cable-logging revealed that decomposition was slower in the control watershed in the more recent observations, though this may reflect lower precipitation that year. These results seem to confirm that microarthropod recovery may be indicative of a restored decomposer community functioning, and that this may be reflective of reconverged abiotic conditions at the site.

Heneghan, L., D.C. Coleman, D.A. Crossley Jr., and Z. Xiaoming. 1999. Nitrogen dynamics in decomposing chestnut oak (Quercus prinus L.) in mesic temperate and tropical forest. Applied Soil Ecology. 13: 169-175.

Abstract
This study examined nitrogen dynamics in decomposing Quercus prinus L. litter, confined in litterbags, in two tropical forests (La Selva Biological Station, Costa Rica and Luquillo Experimental Forest. Puerto Rico) and on temperate forest site (Coweeta Hydrologic Laboratory, NC). Using regressions of %N in the decomposing litter against litter mass remaining. We demonstrated similar concentrations of N at all sites when the amount of litter lost was 50%. By using naphthalene, an arthropod repellent, we examined the effect of microarthropod on the N fluxes in the litterbags. Microarthropod had little effect on the %N remaining. At La Selva, the presence of fauna resulted in a marginally significant increase in litter nitrogen concentrations (p<0.06). At both tropical sites, there was a significant net immobilization of N followed by N mineralization after four months. Although there was a net immobilization of N at Coweeta, this lasted for a longer period and the litterbags had not begun to mineralize N after 10 months. We suggest that the rapid accumulation of N in decomposing litter at the tropical sites during the first few months after leaf fall can result in the retention of mobile nitrogen ions in soils. The subsequent mineralization in later decomposition stages, can make N available to trees during leaf flush.

Heneghan, L., D.C. Coleman, X. Zou, D.A. Crossley Jr., and B.L. Haines. 1998. Soil microarthropod community structure and litter decomposition dynamics: a study of tropical and temperate sites. Applied Soil Ecology. 9: 33-38.

Abstract
The influence of climate, substrate quality and microarthropods on decomposition was studied by comparing the mass loss of litter at three forested sites: two tropical and one temperate. At each site, litterbags containing a dominant local litter were placed in the field in replicated plots. Half the bags were treated with naphthalene to reduce microarthropod abundance. The pattern of mass loss was markedly seasonal at the temperate site. The amount of mass remaining after 250 days were strongly related to the initial %N of the three litter types (r2=0.997). The faunated litterbags lost more mass at all sites and for all litters studied than the litterbags with reduced microarthropod populations. The effect was minimal at the temperate site where the fauna tended to increase the decomposition rate only towards the end of the year. In contrast, the effect of the fauna at the tropical sites was marked within months of the start of the experiment. Species richness of microarthropods in samples of 300 cm2 of leaf litter was similar at the three sites. However, diversity was greatest at the tropical sites.

Heneghan, L., D.C. Coleman, X. Zou, D.A. Crossley Jr., and B.L. Haines. 1999. Soil microarthropod cintribution to decomposition dynamics: tropical-temperate comparisons of a single substrate. Ecology. 80(6): 1873-1882.

Abstract
This study examined the effect of soil microarthropods on the decomposition of a single substrate (Quercus prinus L.) at two humid tropical forests (La Selva, Costa Rica [LAS], and Luquillo Experimental Forest, Puerto Rico [LUQ]) and one temperate forest (Coweeta Hydrologic Station, North Carolina, USA [CWT]). In this litterbag experiment, naphthalene was applied to reduce the microarthropod population density from half of three replicate plots established at each site. This enabled us to quantify the mass loss contributed by the fauna (MLCF) at each site and permitted an analysis of the influence of site-specific differences in the composition of the microarthropod assemblages on decomposition rates. We hypothesized that microarthropod regulation of the microbial populations involved in leaf litter decomposition would be stronger in humid tropical forests, which experience conditions of low climatic variability. In these conditions, there can be an enhanced degree of biotic interactions between microarthropods and their microbial food sources. The elevated extent of these interactions should be expressed as a greater influence of microarthropods at the tropical sites and could result in a site-specific effect of faunal assemblages on decomposition. Decomposition of the oak litter proceeded faster in Puerto Rican and Costa Rican forests than in a temperate forest in North Carolina, USA. Microarthropods had little effect on decomposition in the temperate forest, whereas their influence was pronounced at tropical sites. Mass loss of litter from plots with reduced microarthropod populations was similar at the tropical sites. When plots with intact faunal communities were compared, differences in the tropical sites were apparent, suggesting that there was a site-specific faunal contribution to decomposition at these sites. Oribatid mites constituted a dominant component (41-64%) at each of the sites. Species richness of oribatids and Fisher's alpha diversity were similar in each of the three sites. The Shannon index revealed a lower diversity at LUQ. Abundance of microarthropods was lowest at LAS. Species accumulation curves for each site, though similar in form, were distinctive, as were diversity accumulation patterns in samples of increasing size. There was a positive relationship between species richness and the contribution of the fauna to litter mass loss within each site. Thus, species diversity of decomposer fauna may have important ecosystem consequences, particularly in warm moist tropical forests.

Henning, J.G., and P.J. Radtke. 2006. Ground-based Laser Imaging for Assessing Three-dimensional Forest Canopy Structure. Photogrammetric Engineering and Remote Sensing: 1349-58.

Abstract
Improved understanding of the role of forests in carbon, nutrient, and water cycling can be facilitated with improved assessments of canopy structue, better linking leaf-level processes to canopy structure and forest growth. We examined the use of high-resolution, ground-based laser imaging for the spatially explicit assessment of forest canopies. Multiple range images were obtained and aligned during both leaf-off and leaf-on conditions on a 20m x 40m plot. The plot location was within a mixed broadleaved deciduous forest in western North Carolina. Digital terrain and canopy height models were created for a 0.25m square grid. Horizontal, vertical, and three-dimensional distributions of plant area index, created using gap-fraction based estimation, had 0.5m resolution for a cubic lattice. Individual tree measurements, including tree positions and diameter at breast height, were made from the scanner data with positions, on average, within 0.43m and diameters within 5cm of independent measurements, respectively. Our methods and results confirm that applications of ground-based laser scanning provide high-resolution, spatially-explicit measures of plot-level forest canopy structure.

Henriques Antão, L., Connolly, S. R., Magurran, A. E., Soares, A. and Dornelas, M. (2016), Prevalence of multimodal species abundance distributions is linked to spatial and taxonomic breadth. Global Ecol. Biogeogr.. doi:10.1111/geb.12532

Abstract
Species abundance distributions (SADs) are a synthetic measure of biodiversity and community structure. Although typically described by unimodal logseries or lognormal distributions, empirical SADs can also exhibit multiple modes. However, we do not know how prevalent multimodality is, nor do we have an understanding of the factors leading to this pattern. Here we quantify the prevalence of multimodality in SADs across a wide range of taxa, habitats and spatial extents.

Henry, B.E., Grossman, G.D. 2008. Microhabitat use by blackbanded (Percina nigrofasciata), turquoise (Etheostoma inscriptum), and tessellated (E. olmstedi) darters during drought in a Georgia piedmont stream. Environ Biol Fish. 83: 171-182

Abstract
We used underwater observations to quantify microhabitat use for blackbanded, Percina nigrofaciata, turquoise, Etheostoma inscriptum, and tessellated, E.olmsteadi, darters in a 116 m reach of a Piedmont stream during 2001–2002. The sampling period and the previous 12 months were the first and second driest years on record, respectively. Spring 2002 had the greatest amount of available habitat, and principal component analysis indicated that only one of three species pairs displayed significant differences in microhabitat use during this season. Conversely, in fall 2001 (intermediate microhabitat availability), all three species used significantly different microhabitats. In general, turquoise darters used areas with greater amounts of erosional substrata, tessellated darters occurred over more depositional substrata, and blackbanded darters utilized intermediate microhabitats. During fall 2001, large blackbanded darters (?55 mm SL) occupied faster microhabitats with more erosional substrata, and used a greater variety of depths than smaller conspecifics (40–55 mm). In fall 2001, large turquoise darters (?40 mm) used deeper microhabitats with higher velocities and more erosional substrata than smaller individuals, whereas the opposite was true (?50 mm in faster, more erosional, than >50 mm) in fall 2002. In general, darters did not occur in microhabitats with significantly higher invertebrate abundances, however both blackbanded and tessellated darters occupied microhabitats with higher percentages of Diptera in a single season. The inconsistent responses of darters to microhabitat prey abundance may have been influenced by extreme drought conditions.

Hermann, H.R., M.Mullen, and J.B. Wallace. 1975. Suction disc in Blepharia separata Alexander. Journal of the Georgia Entomological Society 10: 145-150.

Abstract
Suction discs on blepharocerid larvae occur on six segments of the head, thorax and abdomen. All of the structures associated with each disc are below the ventral longitudinal muscle of the body and hence belong to the sternal region. Each disc can be broken down into a zone of membranous cushion, a zone of inverted filaments, a zone of tactile setae and a zone of support. Each zone has a specific function and every zone is important in the suction mechanism. A sternal gland secretes a substance that flows into the zone of inverted filaments. Strong dilator muscle groups are responsible for indefinite suction and release mechanisms.

Hersh, M.H., J.S. Clark, and R. Vilgalys. 2012. Evaluating the impacts of fungal seedling pathogens on temperate forest seedling survival. Ecology, 93: 511-520.

Abstract
Host-specific mortality driven by natural enemies is a widely discussed mechanism for explaining plant diversity. In principle, populations of plant species can be regulated by distinct host-specific natural enemies that have weak or nonexistent effects on heterospecific competitors, preventing any single species from becoming dominant and thus promoting diversity. Two of the first steps in exploring the role of natural enemies in diversity regulation are to (1) identify potential enemies and (2) evaluate their levels of host specificity by determining if interactions between any one host and its enemy have equivalent survival impacts on co-occurring host species. We developed a bioinformatics framework to evaluate impacts of potential pathogens on seedling survival, for both single and multiple infections. Importantly, we consider scenarios not only if there are specialist pathogens for each plant, but also when generalist pathogens have differential effects on multiple host species, and when co-infection has species-specific effects. We then applied this analytical framework to a field experiment using molecular techniques to detect potential fungal pathogens on co-occurring tree seedling hosts. Combinatorial complexity created by 160 plant–fungus interactions was reduced to eight combinations that affect seedling survival. Potential fungal pathogens had broad host ranges, but seedling species were each regulated by different combinations of fungi or by generalist fungi that had differential effects on multiple plant species. Soil moisture can have the potential to shift the nature of the interactions in some plant–fungal combinations from neutral to detrimental. Reassessing the assumption of single-enemy–single-host interactions broadens the mechanisms through which natural enemies can influence plant diversity.

Hertzler, R.A. 1938. Determination of a formula for the 120` V-notch weir. Civil Engineering 8: 756-757.

Abstract
Design of a 120` V-notch sharp-crested weir for accurate measurement of flows up to 26 second-feet is described.

Hewlett, J.D. 1958. Pine and hardwood forest yield. Journal of Soil and Water Conservation 13: 106-109.

Abstract
This paper discusses the theoretical concepts and experimental results which indicate that conifers use more water than hardwoods. Two catchment studies of the effect on water yield of converting hardwoods to white pine are described.

Hewlett, J.D. 1964. Letter to editor on article Groundwater: Definition by H. E. Thomas and L. B. Leopold. Science 144(3625): 1407-1408.

Abstract
This letter questions the definition of groundwater used in the article.

Hewlett, J.D. 1964. Water or forest - can we have all we need of both? Frontiers of Plant Science 17: 2-3.

Abstract
The author outlines an experiment with a transpiration inhibitor and cites benefits possible if this or related tests succeed.

Hewlett, J.D. 1969. In Defense of Experimental Watersheds. Water Resources Research. 5(1): 306-316.

Abstract
Recent criticisms discount the contribution of experimental watersheds to the science of hydrology' and to watershed management. The critics cite as disadvantages the cost of experimental watersheds, their unrepresentativeness, leakiness, difficulty in applying results to other areas, and the lack of progress in basic knowledge about hydrologic processes. Some critics propose mathematical synthesis, statistical analysis, plot studies, soil moisture studies, meteorological methods, and the study of individual hydrologic processes as alternatives to experimental watersheds. The criticisms lack weight, because published results of catchment experiments were not carefully reviewed. The alternatives are obviously aids rather than substitutes for experiments on watersheds. By reference to recent and older results, the authors argue that the experimental watershed method has produced much of our present knowledge about the land phase of the hydrologic cycle and man's influence on it, that the method is sound, and that its future in &iy comprehensive research program is secure.

Hewlett, J.D. 1971. Comments on the catchment experiment to determine vegetal effects on water yield. Water Resources Bulletin. 7(2): 376-381.

Abstract
So far most applicable knowledge about forests and water yield has come from catchment experiments. Perhaps even more practical information might have been secured during the past twenty years if more and better designed catchment experiments had been undertaken. At the very least, the old question of the main effects of vegetation on total basin water yield should now be settled, and we should be in a position to write management prescriptions containing reliable estimates of differing water yields under crop, pasture, brush and forest lands. As things are, managers and policy makers are being forced to decide what combinations of vegetal cover and land use best favor water yield before the scientific community has fully agreed on some of the salient aspects of the problem. This has led to considerable confusion in the minds of land managers in many regions of the world and may continue to do so for some time. The catchment experiment remains the surest way to furnish each region with practical knowledge of local vegetation-water-yield relations.

Hewlett, J.D., and A.R. Hibbert. 1961. Increases in water yield after several types of forest cutting. International Association Scientific Hydrology Bulletin 6(3): 5-17.

Abstract
Effects of timber and brush removal on water yields from small watersheds are examined in the light of 25 years of hydrologic research at Coweeta.

Hewlett, J.D., and A.R. Hibbert. 1963. Moisture and energy conditions within a sloping soil mass during drainage. Journal of Geophysical Research 68: 1081-1087.

Abstract
A model of a sloping soil profile is used to show that slow, unsaturated flow of soil moisture above the water table furnishes much of the sustained streamflow between storms in mountain land.

Hewlett, J.D., and J.D. Helvey. 1970. Effects of forest clear-felling on the storm hydrograph. Water Resoures Research 6: 768-782.

Abstract
A statistical analysis of all major storm hydrographs before and after clear-felling a mature hardwood forest on a 108-acre calibrated catchment revealed that, after felling, stormflow volume was significantly (01 level) increased 11 percent overall, or 0.23 inch at the mean stormflow volume of 2.1 inches. Peak discharge increased slightly after felling (about 6 c.f.s.m. or 7 percent at the mean peak flow of 92 c.f.s.m.). Time to peak, recession time, and duration of stormflow were tested to an accuracy within 10 percent of their respective mean values (0.05 level), but no treatment effect was detected. Increases in stormflow as a result of felling ranged from 0 in small floods to 1.9 inches during a record 7-day flood sequence.

Hewlett, J.D., and J.E. Douglass. 1961. A method for calculating error of soil moisture volumes in gravimetric sampling. Forest Science 7: 265-272.

Abstract
A method for calculating error of soil moisture volumes in gravimetric sampling is presented. Limitations in sampling soil density and percentage of moisture to determine inches of water render the gravimetric method a poor tool for hydrologic research.

Hewlett, J.D., and L.J. Metz. 1960. Watershed management research in the Southeast. Journal of Forestry 58: 269-271.

Abstract
This article is a review of research on watershed management at the Coweeta Hydrologic Laboratory and Union Research Center.

Hewlett, J.D., G.B. Cunningham, and C.A. Troendle. 1977. Predicting stormflow and peakflow from small basins in humid areas by the R-index method. Water Resources Research 13: 231-253.

Abstract
A nonlinear equation was fitted to 468 stormflows on 11 forested basins from New Hampshire to South Carolina, providing an equation for use on forest and wild lands in humid regions. Stormflow (Q) is a function of R, P and I, where R, the average storage capacity index, is the mean value of Q/P. P is storm rainfall, and I is the initial flow rate. S.E. is 0.3 inch of stormflow. Peakflow was similarly estimated (S.E. 26 ft3/sec/mi2). The R-index method is proposed as a practical tool in wild land management. When tested against the runoff curve method on four independent basins, predictions by the R-index method were considerably more accurate.

Hewlett, J.D., J.C. Fortson, and G.B. Cunningham. 1977. The effect of rainfall intensity on storm flow and peak discharge from forest land. Water Resources Research 13: 259-265.

Abstract
Analysis of a 30-year record of rainfall and storm flow (545 events) from a forested watershed in the southern Appalachians was made to determine whether rainfall intensity influences storm flow volume or peak discharge. For all practical purposes, rainfall intensities during storms had no effect on storm flow volumes. Storm rainfall, antecedent flow, season, and duration of the rainstorm accounted for 86.4 percent of total variation in the log of storm flow. Addition of maximum 60-, 30-, 15-, and 5-minute intensities raised this to 86.7 percent. Only 4.7 percent of the total variation in the log of peak flow was attributable to intensity.

Hewlett, J.D., J.C. Fortson, and G.B. Cunningham. 1984. Additional tests on the effect of rainfall intensity on storm flow and peak flow from wild-land basins. Water Resources Research 20: 985-989.

Abstract
Further evidence that hourly rainfall intensity has no appreciable effect on storm flows, and only a small effect on peak flows, was adduced from statistical analysis of 4094 storm events on 15 drainage basins ranging from 13 to 760 ha in area. The basins range from humid to semiarid climates and from flat to steep topography and contain various covers (forest, brush, grass, and swamp). The marginal coefficient of determination accounted for by maximum hourly rain intensity averaged about 1% for storm flows and about 10% for peak flows. The dependence of storm flows on rain intensity did not increase in larger storms or on more responsive basins, but rather the opposite.

Hewlett, J.D., J.E. Douglass, and J.L. Clutter. 1964. Instrumental and soil moisture variance using the neutron-scattering method. Soil Science 97: 19-24.

Abstract
The variance in estimates of soil moisture as determined by the neutron-scattering method is examined and related to field data from two research areas. Instrument and timing errors are shown to contribute insignificantly to the standard error of estimate. Furthermore, their contribution to estimates of moisture change with time is negligible as long as the timing interval used at each observation exceeds 30 seconds.

Hibbert, A.R. 1969. Water yield changes after converting a forested catchment to grass. Water Resources Research 5: 634-640.

Abstract
After a forested catchment was converted to grass, the amount of evapotranspiration was closely related to the amount of grass produced. During years when grass production was high, water yield from the catchment was about the same as or less than the expected yield from the original forest. As grass productivity declined, water yield gradually increased until it exceeded the predicted yield from the forest by over 5 inches annually. The grass appeared to evaporate more water early in the spring and less water late in the summer than the original forest cover.

Hibbert, A.R., Troendle, C.A., 1988. Streamflow Generation by Variable Source Area. In Ecological Studies: analysis and synthesis, Vol. 66. In the series analytic: Forest hydrology and ecology at Coweeta. W.T. Swank and D.A. Crossley, Jr., eds. 1988 Springer-Verlag New York, Inc.

Abstract
For many years, hydrologists and engineers alike have attempted to describe and model the processes that generate streamflow from rainfall. Modern understanding of runoff processes expanded rapidly in the twentieth century. Horton (1933) proposed that the soil surface partitions rainfall into overland flow and ground water. Simply stated, when rainfall rate exceeds the infiltration capacity of the soil, the excess water flows over the surface to become the primary source of storm flow. Base flow, that which maintains streams between rains, issues from ground water aquifers sloping gently to the channels. During the 1930s and 1940s, Horton and his coworkers firmly established the idea that infiltration was dominant in the runoff process. The central criticism of the Hortonian concept is that too much emphasis was placed on rain that fails to infiltrate the soil, and not enough on that which does infiltrate. The Hortonian concept of storm flow generation prevailed for many years, and is still valid when applied to land surfaces that do not accept water readily. Much of the western rangelands fall in this category. By the mid 1930s, however, foresters in the eastern United States were becoming increasingly aware that overland flow was not being generated on forest slopes in sufficient quantity to account for storm flows from first- and second-order streams (Lowdermilk 1933; Hursh 1936; Hursh and Brater 1941). Horton (1943) recognized that some soils were capable of absorbing all the water that fell on them. With reference to the Little Tallahatchie drainage basin in Mississippi, he observed that "owing to somewhat unusual conditions, surface runoff rarely occurs from soil well protected by forest cover."

Hicks, N.G., and S.M. Pearson. 2003. Salamander diversity and abundance in forests with alternative land use histories in the Southern Blue Ridge Mountains. Forest Ecology and Management. 177: 117-130.

Abstract
The diversity and abundance of terrestrial salamanders were compared at 12 forest stands having three different land use histories: (a) success ional forest established on abandoned farmland; (b) second/third growth forests that had experienced timber harvest; (c) stands having few to no alterations due to land use. Populations were estimated using pitfall trapping conducted during July 1997 1997-June 1998 in the Southern Blue Ridge Province of the Southern Appalachian Mountains. Salamander diversity did not differ among land use categories; however, abundances were greater in the older, least-altered stands. Abundances were positively correlated with late successional qualities of forest, such as increased domination by mesophytic tree species and increased availability of wood debris. However, we did not find large differences between stands that had experienced previous agricultural uses and those that had not been farmed, only logged. At our sites, enough time had passed since agricultural use that any differences between agricultural and forestry uses had diminished. These results show both the sensitivity of salamanders to past habitat alterations and the resiliency of these populations in their ability to recover in these ecosystems given sufficient time.

Hicks, N.G., M.A. Menzel, and J. Laerm. 1998. Bias in the determination of temporal activity patterns of syntopic peromyscus in the Southern Appalachians. Journal of Mammalogy. 79(3): 1016-1020.

Abstract
We compared inferred activity patterns of two syntopic rodents, Peromyscus leucopus and P. maniculatus, in western North Carolina. Activity patterns were derived from capture-frequency data obtained from Sherman live-traps equipped with digital timers following different trapping protocols. We tested the hypothesis that no differences would be observed in frequency distribution of captures from trapping grids monitored only in the morning (control) compared with grids where captured animals were released during the night and in the morning (treatment). Distributions of frequencies of captures on control and treatment grids were significantly different. On control grids, capture frequencies (based on 3-h intervals) of both species were higher in the first 3 h after sunset and decreased thereafter throughout the night, but frequencies of captures of both species were uniform throughout the night on treatment grids. Photographic records from automated cameras suggested increasing levels of activity throughout the night. Activity patterns derived from camera data were different from those derived from the control and treatment grids. Inferences regarding activity patterns are sensitive to method and trapping-protocol bias.

Hill, J., and G.D. Grossman. 1987. Effects of subcutaneous marking on stream fishes. Copeia(2): 492-495.

Abstract
A long-term marking technique for fishes must permit a large number of unique marks, be long lasting, not increase mortality, diminish growth, or alter behavior, and be inexpensive and usable in the field. Subcutaneous injections with acrylic paints generally satisfy these criteria. In previous studies, fish were marked in one position or with a single color; hence, the effects of mark position or color on recapture frequency are unknown. Herein, we evaluate the effects of mark position and color on growth, survivorship, longevity, and recapture success for several Southeastern stream fishes.

Hill, J., and G.D. Grossman. 1987. Home range estimates for three North American stream fishes. Copeia(2): 376-380.

Abstract
Home ranges of three fish species inhabiting a fourth order stream in the Blue Ridge Mountains of North Carolina were estimated. Cottus bairdi, Rhinichthys cataractae and Clinostomus funduloides moved an average of 12.9, 13.4, and 19.3 respectively, between captures. Mean time interval between captures was 128 d; 86% of recaptures were in the stream section of previous capture. Individuals may not have moved throughout the entire section length (mean length = 10.4 m); thus, these values likely overestimate actual movements.

Hille Ris Lambers, J., and J.S. Clark. 2003. Effects of dispersal, shrubs, and density-dependent mortality on seed and seedling distributions in temperate forests. Canadian Journal Forestry Research. 33: 783-795.

Abstract
Processes limiting recruitment of trees may have large impacts on forest dynamics. In this paper, we determined the effects of dispersal, shrubs (Rhododendron maximum), and density-dependent mortality on seed and seedling distributions of Southern Appalachian trees. We quantified the spatial distribution of seed rain, seed bank densities, first-year seedlings, and older than first-year seedlings in five vegetation plots. We fit models to these data assuming effects of limited dispersal, R. maximum (an understory shrub), and (or) density-dependent mortality (as well as a null model with none of these effects) and used best-fitting models to indicate which processes affected a particular species. We found that all factors examined limit species distributions, and thus, affect seedling dynamics. Seedling densities are higher near parent trees long after dispersal occurs. This pattern is less frequently observed for animal-dispersed species than for wind-dispersed species, presumably due to secondary dispersal of seeds by animals. Seedling densities of five species are decreased beneath R. maximum. Shade tolerance does not explain which species are affected, suggesting that factors other than low light are responsible for increased seedling mortality under this shrub. Our results suggest that density-dependent mortality affects four species, decreasing seedling densities close to parent trees. Dispersal, density-dependent mortality, and R. maximum all act in ways that may promote or limit diversity, illustrating that multiple factors are likely to control species diversity.

Hille Ris Lambers, J., and J.S. Clark. 2005. The benefits of seed banking for red maple (Acer rubrum): maximizing seedling recruitment. Canadian Journal Forestry Research. 35: 806-813.

Abstract
Seed banking is assumed to be unimportant for temperate trees, because their seeds are short-lived in soils. However, even short-term seed banking could increase recruitment and affect population dynamics of seed-banking trees. To investigate this possibility, we examined early life-history stages of red maple (Acer rubrum L.), an abundant seed-banking tree in eastern forests. We found that seed banking benefits red maple by increasing germination when seedling survival is likely. Most red maple seeds germinate soon after spring dispersal, when seedling survival is high, or postpone germination to the following growing season, once seedling survival becomes less likely late in the summer. This occurs because seed dormancy increases during the growing season, matching a concurrent decrease in seedling survival. Our results and those of other studies suggest seed dormancy is increased by the same environmental factors (low light and low moisture) that also decrease seedling survival. We speculate that early life-history traits, including seed banking, may have contributed to this species¼ increased abundance in eastern deciduous forests in the last century.

Hille Ris Lambers, J., J.S. Clark, and B. Beckage. 2002. Density-dependent mortality and the latitudinal gradient in species diversity. Nature. 417: 732-735.

Abstract
Ecologists have long postulated that density-dependent mortality maintains high tree diversity in the tropics1-6. If species experience greater mortality when abundant, then more rare species can persist 1,2,7-9.+ Agents of density-dependent mortaliy (such as host-specific predators, and pathogens) may be more prevalent or have stronger effects in tropical forests, because they are not limited by climatic factors 1-5. If so, decreasing density-dependent mortality with increasing latitude could partially explain the observed latitudinal gradient in tree diversity4-6. This hypothesis has never been tested with latitudinal data. Here we show that several temperate tree species experience density-dependent mortality between seed dispersal and seedling establishment. The proportion of species affected is equivalent to that in tropical forests6, 10-16, failing to support the hypothesis that this mechanism is more prevalent at tropical latitudes. We further show that density-dependent mortality is misinterpreted in previous studies. Our results and evidence from other studies suggest that density-dependent mortality is important in many forests. Thus, unless the strength of density-dependent mortality varies with latitude, this mechanism is not likely to explain the high diversity of tropical forests.

Hille Ris Lambers, J., J.S. Clark, and M. Lavine. 2005. Implications of seed banking for recruitment of southern Appalachian woody species. Ecology. 86(1): 85-95.

Abstract
Seed dormancy is assumed to be unimportant for population dynamics of temperate woody species, because seeds occur at low densities are short lived in forest soils. However, low soil seed densities may result form low seed production, and even modest seed longevity can buffer against fluctuating seed production, potentially limiting density-dependent mortality and ensuring that seeds are available for germination when recruitment success is likely. To investigate whether seed banking affects woody seedling dynamics in the southern Appalachians, we monitored seed rain, seed bank, and seedling densities to (1) determine the prevalence of seed banking among southern Appalachian woody species, (2) quantify annual seed mortality rates for three seed-banking species using a Bayesian statistical approach, and (3) assess whether or not the ability to seed bank affects recruitment rates. We found that the seeds of eight woody taxa (Acer rubrum, Betula spp., Liriodendron tulipifera, Nyssa sylvatica, Robinia pseudoaccacia, Rubus spp., Sassafras albidum, and Vitis sp.) remain viable in the soil for more than one year. Seeds of six taxa (Amelanchier spp., Acer pennsylvanicum, Carya spp., Quercus prinus, Quercus Rubra and Tsuga canadensis) were never found in the soil seed bank, despite high seed production and germination. For three species, a substantial proportion of seeds available for germination came from dispersal events two or more years in the past (Acer rubrum 12-37%, Betula spp. 59-73%, Liriodendron tulipifera 40-76%), even though annual seed mortality was high ( Acer rubrum 70-98%, Betula spp. 21-81%, Liriodendron tulipifera 12-59%). In years when no seeds fall in local microsites (approximately one in five years), seed banks are the only source of seedling recruitment for these species. Comparing our results to those of previous studies led to valuable insights: first, the seeds of Acer rubrum and Betula spp. Suffer high mortality while being incorporated into the seed bank; and second, that seed decay varies greatly over relatively small spatial scales (i.e. within a watershed). Taken together, these results demonstrate that seed banking may play a critical role during woody seedling recruitment in temperate forests.

Hille Ris Lambers,J, JS Clark, and B Beckage. 2002. Density dependent mortality and the latitudinal gradient in species diversity. Nature 417:732-735.

Abstract
Ecologists have long postulated that density-dependent mortality maintains high tree diversity in the tropics1, 2, 3, 4, 5, 6. If species experience greater mortality when abundant, then more rare species can persist1, 2, 7, 8, 9. Agents of density-dependent mortality (such as host-specific predators, and pathogens) may be more prevalent or have stronger effects in tropical forests, because they are not limited by climatic factors1, 2, 3, 4, 5. If so, decreasing density-dependent mortality with increasing latitude could partially explain the observed latitudinal gradient in tree diversity4, 5, 6. This hypothesis has never been tested with latitudinal data. Here we show that several temperate tree species experience density-dependent mortality between seed dispersal and seedling establishment. The proportion of species affected is equivalent to that in tropical forests6, 10, 11, 12, 13, 14, 15, 16, failing to support the hypothesis that this mechanism is more prevalent at tropical latitudes. We further show that density-dependent mortality is misinterpreted in previous studies. Our results and evidence from other studies suggest that density-dependent mortality is important in many forests. Thus, unless the strength of density-dependent mortality varies with latitude, this mechanism is not likely to explain the high diversity of tropical forests.

Hoffman, Ava (2012). Estimating Tree Transpiration Accurately Depends on Wood Type and Species: A Study of Four Southern Appalachian Tree Species. The Oculus: The Virginia Journal of Undergraduate Research 11:30-34. University of Virginia.

Abstract
The measurement of sap movement in trees is a valuable way to estimate forest evapotranspiration, or the return of water vapor to the atmosphere. The accuracy of these measurements is essential to determining forest evapotranspiration. Importantly, forest evapotranspiration is a major component of water budget, and subsequent water lost through this process affects other fluxes such as streamflow and surface water supply. Using a dual thermal dissipation probe system inserted into sapwood, the difference in temperature (AT) between the two probes can be related to sap flux density using an empirically derived equation. The universality of the power function coefficients proposed by Granier in this empirical equation has recently come into question regarding different tree species. Notably, Granier's coefficients may not be universal among different wood types and among trees with varying sapwood to heartwood ratios. It has been suggested that each specie* should be validated before using the universal coefficients. Using four tree species indigenous to the southern Appalachians (Betula lenta, Liriodendron tulipifera, Nyssa sylvatica, Rhododendron maximum), this study estimates sap flux through excised woody stems using two independent methods: gravimetric and thermal dissipation. This study evaluates whether the species differ significantly among each other by comparing aforementioned gravimetric measurements. Replicates of excised stems were selected from trees growing in the Coweeta basin. Our results indicated that three of the four species require coefficients that differ from Granier's (Betula, Nyssa, Rhododendron). Furthermore, there are significant differences between all but two of the species (Liriodendron and Rhododendron). Future studies will focus on testing other major tree species in the southern Appalachians to improve the accuracy of stand-level transpiration measurements.

Hogg, D.C. 1968. Millimeter-wave communication through the atmosphere. Science 159(3810): 39-46.

Abstract
Millimeter-length radio wave bands are not utilized for communication because water vapor in the atmosphere absorbs energy at these frequencies and limits distance of transmission. Rain is one of several causes of radio wave attenuation discussed in this review. Data collected for the Illinois State water survey by a raindrop camera at Coweeta Hydrologic Laboratory are used with data from other sites to estimate the degree of radio interference and develop design guidelines for communications systems.

Hogue, C.L., and T. Georgian. 1986. Recent discoveries in the Blepharicera tenuipes group, including descriptions of two new species from Appalachia (Diptera: Blephariceridae). Contributions in Science 377: 1- 20.

Abstract
Two new species of Blepharicera (B. appalachiae and coweetae) are described in the Blepharicera tenuipes group. Both occur in the southern half of the Appalachian Mountains in eastern North America, the former of wide distribution, the latter restricted to a small portion of the upper Little Tennessee drainage. A key to all the known stages in the B. tenuipes group is provided along with new information on ecology, distribution, and phylogeny (for which the sister Blepharicera micheneri group is newly recognized).

Hoover, M.D. 1945. Careless skidding reduces benefits of forest cover for watershed protection. Journal of Forestry 43: 765-766.

Abstract
Careless skidding creates channels which concentrate runoff from road surfaces and cause erosion which is unnecessary if roads are carefully located and constructed. Techniques which minimize erosion from skid roads are presented.

Hoover, M.D. 1952. Water and timber management. Journal of Soil and Water Conservation 7: 75-78.

Abstract
As demand for water increases, management of forested head-waters assumes greater importance. Compatibility of objectives in the management of timber and water is demonstrated, and management practices which protect the values of each resource are stressed.

Hornbeck, J.W., and W.T. Swank. 1992. Watershed ecosystems analysis as a basis for multiple-use management of eastern forests. Ecological Applications 2(3): 238-247.

Abstract
There is ever-increasing competition for the many uses and natural resources of forests in the eastern United States. Multiple-use management has long been a stated goal for the forests, but application has been problematic and seldom satisfactory to all users. There is a need to incorporate more science into management decisions for Eastern forests, and thereby convincingly demonstrate to forest managers and the public why certain combinations of uses may or may not be compatible. One proven approach for doing this is to use watershed ecosystem analysis. Small watersheds, usually <100 ha in area, serve as a convenient ecosystem for studying how forests function in terms of cycling energy, nutrients, and water. Results of these studies allow assessments of forest health and productivity, and evaluations of impacts of both natural and human-related disturbances. This paper provides illustrations of how watershed ecosystem analysis can be used to study the effects of current harvesting practices, acidic deposition, and past land use. The paper also shows how recommendations for land use are derived from watershed ecosystem analysis, and how they are put into practice.

Hornick, L E., J.R. Webster, and E.F. Benfield. 1981. Periphyton production in an Appalachian mountain trout stream. American Midland Naturalist 106: 22-36.

Abstract
Periphyton primary production was investigated in a second-order Appalachian Mountain stream and two of its tributaries. Using 14C fixation in recirculating chambers, estimates averaged 2.27 mg C m-2 h-1 in the mainstream and 1.65 and 1.37 mg C m-2 h-1 in the two tributaries. Abiotic factors most influential on primary production rates were light, streamflow and inorganic carbon. Based on annual budgets, the estimated stream energy input attributable to autochthonous primary production was about 3 percent of allochthonous inputs. However, because of high nutritive value and timing, autochthony may be more important than indicated by annual budgets.

Horton, J. L., Barton D. Clinton, John F. Walker, Colin M. Beier, and Erik T. Nilsen 2009. Variation in Soil and Forest Floor Characteristics Along Gradients of Ericaceous, Evergreen Shrub Cover in the Southern Appalachians. Castanea 74(4): 340-252.

Abstract
Ericaceous shrubs can influence soil properties in many ecosystems. In this astudy, we examined how soil and forest floor properties vary among sites with different aericaceous evergreen shrub basal area in the southern Appalachian mountains. We randomly alocated plots along transects that included open understories and understories with varying aamounts of Rhododendron maximum (rosebay rhododendron) and Kalmia latifolia (mountain alaurel) at three sites. The three sites were a mid-elevation ridge, a low-elevation cove, and a ahigh-elevation southwest-facing slope. Basal area of R. maximum was more correlated with soil aproperties of the forest floor than was K. latifolia. Increasing R. maximum basal area was acorrelated with increasing mass of lower quality litter and humus as indicated by higher C:N aratios. Moreover, this correlation supports our prediction that understory evergreen shrubs may ahave considerable effect on forest floor resource heterogeneity in mature stands.

Hu, S., D.C. Coleman, C.R. Carroll, P.F. Hendrix, and M.H. Beare. 1997. Labile soil carbon pools in subtropical forest and agricultural ecosystems as influenced by management practices and vegetation types. Agriculture, Ecosystems and Environment. 65(1): 69-78

Abstract
Carbon storage in agricultural and forest soils has attracted at tention recently due to its potential as a substantial carbon sink. Labile soil C pools are especially important because they are more vulnerable to climatic c hange and disturbance and play vital roles in nutrient cycling. Southern Appala chian forest soils and those from conventional tillage (CT), no-tillage (NT) and fescue sods at three sites in the Georgia piedmont were analyzed for total C, t otal N, carbohydrates, and microbial biomass C. The sizes of soil labile C pool s and their contributions to the total soil C pool differed significantly among ecosystems. The highest carbohydrate contents and microbial biomass C were foun d in forest soils, but agricultural soils had a significantly higher proportion of the soil organic matter present as carbohydrates and as microbial biomass. T his difference probably reflects the quality of soil organic matter. Soil microb ial biomass C was more sensitive to changes in management regimes than soil carb ohydrates. Management practices significantly affected organic C, carbohydrate c ontents, microbial biomass C and organic C turnover rates in agricultural soils, whereas differences in the quality of organic input due to different vegetation types substantially influenced soil labile C pools in forest soils. High manno se-to-xylose ratios in highly sandy agricultural soils indicate that plant-deriv ed materials are rapidly metabolized by microorganisms and that organic C protec tion in sandy soils is largely dependent on reducing microbial access through ef fective residue management such as surface placement.

Hubbard, R.M., J.M. Vose, B.D. Clinton, K.J. Elliott, and J.D. Knoepp. 2004. Stand restoration burning in oak-pine forests in the southern Appalachians: effects on aboveground biomass and carbon and nitrogen cycling. Forest Ecology and Management. 190: 31

Abstract
Understory prescribed burning is being suggested as a viable management tool for restoring degraded oakvpine forest communities in the southern Appalachians yet information is lacking on how this will affect ecosystem processes. Our objectives in this study were to evaluate the watershed scale effects of understory burning on total aboveground biomass, and the carbon and nitrogen pools in coarse woody debris (CWD), forest floor and soils. We also evaluated the effects of burning on three key biogeochemical fluxes; litterfall, soil CO2 flux and soil net nitrogen mineralization. We found burning significantly reduced understory biomass as well as the carbon and nitrogen pools in CWD, small wood and litter. There was no significant loss of carbon and nitrogen from the fermentation, humus and soil layer probably as the result of low fire intensity. Burning resulted in a total net loss of 55 kg ha1 nitrogen from the wood and litter layers, which should be easily replaced by future atmospheric deposition. We found a small reduction in soil CO2 flux immediately following the burn but litterfall and net nitrogen mineralization were not significantly different from controls throughout the growing season following the burn. Overall, the effects of burning on the ecosystem processes we measured were small, suggesting that prescribed burning may be an effective management tool for restoring oakvpine ecosystems in the southern Appalachians.

Hunter, M.D. 2001. Insect population dynamics meets ecosystem ecology: effects of herbivory on soil nutrient dynamics. Agricultural and Forest Entomology. 3: 77-84.

Abstract
In reality, the idea that insect herbivores may regulate nutrient availability and primary production has no fundamental link with theories of mutualism or plant fitness. Plant productivity is measured in different units (carbon per m2 per year) and at a different level of organization (the community) than is fitness (proportional representation in the next generation measured at the level of individual plants). Theories of herbivore-mediated changes in nutrient cycling need not be found guilty by association with controversial views of herbivores as mutualists. Given the recent interest in the role of species in ecosystems (Jones & Lawton, 1995) and publications by Schowalter (2000) and Belovsky & Slade (2000), it is worth re-examining potential effects of insect herbivores on ecosystem function. The discussion that follows is limited to the effects of foliar-feeding herbivores on soil nutrient dynamics and subsequent productivity. Effects of wood-boring insects on nutrient dynamics are well documented (e.g. Dale et al., 1990) and, although root feeding insects can influence nutrients in soils (Maron & Connors, 1996; Maron & Jefferies, 1999; Hunter 2001), the effects of below-ground fauna on nutrient dynamics are a whole other can of worms, so to speak. In addition, although the focus of this article will be insect folivores, I beg your indulgence if a few four-legged and eight-legged herbivores make brief appearances to illustrate an occasional ecological principle.

Hunter, M.D., and R. E. Forkner. 1999. Hurricane damage influences foliar polyphenolics and subsequent herbivory on surviving trees. Ecology. 80(8): 2676-2682

Abstract
Hurricane damage results in tree mortality and variation in both light and nutrient availability for the individuals that remain. In turn, resource availability influences the interactions between plants and insect herbivores. We report effects of Hurricane Opal on the phenolic chemistry and levels of defoliation on surviving trees at the Coweeta Hydrologic Laboratory in North Carolina. We measured foliar astringency, hydrolysable tannins, and condensed tannins in the foliage of red maple and red oak saplings in hurricane-damaged and undamaged sites. We estimated inorganic nitrogen and phosphorus availability in the soil, and the accumulated leaf area removed by insect herbivores.

Hunter, M.D., C.R. Linnen, and B.C. Reynolds. 2003. Effects of endemic densities of canopy herbivores on nutrient dynamics along a gradient in elevation in the southern Appalachians. Pedobiologia. 47: 231-244.

Abstract
In southern Appalachian forests, outbreaks of insect herbivores have been shown repeatedly to increase the availability of nutrients in soil and the export of nitrate in forest streams. The mechanisms underlying herbivore-induced changes in nutrient dynamics include inputs of insect frass (feces) and modification of precipitation as it passes through the forest canopy (throughfall). Here, we consider the effects of endemic (non-outbreak) populations of insect herbivores on soil processes in the southern Appalachians. We measured inputs of frass and throughfall at three elevations at the Coweeta Hydrological Laboratory, North Carolina. We also measured soil nutrient availability and soil respiration. Inputs of total frass, frass nitrogen and frass carbon exhibited early-and late-season peaks, with those peaks occurring earlier at low elevation where leaf flush begins first. The C: N ration generally increased over time at all elevations, presumably reflecting seasonal declines in foliar nitrogen. Nitrate in throughfall generally increased over time, whereas throughfall phosphate declined and throughfall ammonium remained relatively constant. Relationships among frass deposition and throughfall nutrients varied with elevation. At low elevation, frass nitrogen was strongly correlated with throughfall nitrate, but this relationship was absent at mid and high elevation. The relationships between frass deposition and throughfall ammonium were inconsistent among elevations. The availabilities of nitrate and ammonium in soil were both related to frass deposition. For example, frass deposition in May explained about 62% of the variance in soil nitrate availability. Soil respiration exhibited summer maxima at all elevations and was related primarily to soil temperature. There was also a weak positive relationship between the C: N ratio of frass and soil respiration. Overall, we suggest that endemic densities of canopy herbivores can influence forest soil processes, but that the relationships exhibit pronounce spatial and temporal variability.

Hunter, M.D., S. Adl, C.M. Pringle, and D.C. Coleman. 2003.Relative effects of macroinvertebrates and habit on the chemistry of litter during decomposition. Pedobiologia. 47: 101-115.

Abstract
During the decomposition of terrestrial leaf litter, the concentrations of lignin, tannin, cellulose, hemicellulose, nitrogen, and carbon are known to change. These chemical changes have been associated with subsequent colonization and activity of decomposer flora and fauna. Here, we report that chemical changes in litter during the first twelve months of decomposition are affected by macroinvertebrate activity. Moreover, chemical changes are associated most closely with the activities of invertebrate predators. Using litter bags that either excluded (fine mesh) or allowed access by (coarse mesh) macroinvertebrates, we followed the concentrations of lignin, tannin, cellulose, hemicellulose, nitrogen, and carbon in the litter of Liriodendron tulipifera, Quercus prinusi and Rhododendron maximum in a North Carolina forest ecosystem. We also compared chemical changes in these litters at a riparian site and an upland site within the forest. The exclusion of macroinvertebrates decreased concentrations of nitrogen and total phenolics in the litter of L. tulipifera, increased concentrations of cellulose and condensed tannin in Q. prinus litter, and increased the concentrations of condensed tannin in R. maximum litter in the riparian zone. Although fine mesh bags excluded most macroinvertebrates, the greatest effects of exclusion were upon ants and spiders, not macroinvertebrate decomposers. Our data therefore suggest that predator-mediated changes in the decomposer communities were responsible for observed shifts in litter chemistry. Predator effects on litter chemistry were likely mediated by their interactions with fungivorous and bacterivorous fauna. For example, Collembola populations were 34% higher in litter bags from which macroinvertebrates were excluded. Litter chemistries also differed between the riparian and upland sites. For both L. tulipifra and R. maximum, effects of habitat were limited to higher concentrations of condensed tannin in the upland site. In contrast, habitat effects upon the litter chemisiry of Q. prinus were pervasive. Specifically, Q. prinus litter in the upland habitat exhibited slower increases in lignin, more stable concentrations of cellulose, slower increases in hemicellulose, higher concentrations of total phenolics, and higher concentrations of hydrolysable tannins than did litter in the riparian habitat. Overall, our data provide the first evidence that predators in the litter of deciduous forests can influence the chemistry of litter during the decomposition process.

Hursh, C.R. 1928. Litter keeps forest soil productive. Southern Lumberman 133(1734): 219-221.

Abstract
Forest soils are, for the most part, self-fertilized by organic material derived from litter. Litter has a beneficial effect on the ability of soil to absorb and retain moisture, on chemical characteristics, and on biological activity. The effects of fire and aspect on litter production are discussed.

Hursh, C.R. 1931. Abandoned mountain farms an erosion menace but a forestry opportunity. Farmers Federation News 11(12): 3-5.

Abstract
The author describes agricultural practices which leave mountain soils exposed to erosion and recommends that slopes unsuitable for agriculture not be cleared and that abandoned land be converted to pasture or forest cover to prevent erosion.

Hursh, C.R. 1942. Naturalized roadbanks. Better Roads 12(6, 7): 13-15, 24-25, 17-20.

Abstract
Naturalization and stabilization of roadbanks by vegetation are discussed as part of road construction. Experiments begun in 1934 at the Appalachian Forest Experiment Station indicate that seeding, planting, fertilizing, and mulching are practical methods of stabilizing banks.

Hursh, C.R. 1942. The naturalization of roadbanks. Roads and Bridges (Can.) 80(7): 22-26, 131-134.

Abstract
Naturalization and stabilization of roadbanks by vegetation are discussed as part of road construction. Experiments begun in 1934 at the Appalachian Forest Experiment Station indicate that seeding, planting, fertilizing, and mulching are methods of stabilizing banks.

Hursh, C.R. 1945. Plants, shrubs, trees in slope stabilization. Contractors and Engineers Monthly 42(6): 26-27.

Abstract
Natural vegetation is the most efficient and esthetically pleasing means of roadbank stabilization. Deep-rooted legumes such as perennial lespedeza and Scotch broom together with native woody shrubs are advised. In the Eastern States, rainfall and site conditions favor a plant succession toward a forest cover, but the possibility of trees being uprooted or interfering with viewing distance shoud be taken into account.

Hursh, C.R. 1946. The Eastern Forester and His Watersheds. Journal of Forestry. 44(12): 1037-1040.

Abstract
As foresters, we profess to be the guardians of water resources. The author asks how well is the average forester able to live up to this responsibility. Some helpful reference points and concepts regarding water resources are presented. The author writes that a progressive forester should be as well informed on water as on any other forest resource. This may call for some special effort for many of us. As water comes more into the picture, we who teach and we who practice will be expected to master the subject as we have mastered other new problems that have arisen in the past.

Hursh, C.R. 1946. Where little waters write big stories. American Forests 52: 574-577, 603.

Abstract
The author describes watershed experiments underway at the Coweeta Hydrologic Laboratory and discusses what has been learned about water yield and erosion from studies of complete removal of forests, of clearing and cultivating steep forest lands, and of woodland grazing.

Hursh, C.R. 1947. Water resource management. North Carolina Engineer 3(2): 9-12, 40.

Abstract
This article is a general summary on the research facilities, program, and findings at the Coweeta Hydrologic Laboratory .

Hursh, C.R. 1947. Watershed experiments conducted in giant outdoor laboratory. Timber Topics 10(4): 2-4, 9.

Abstract
The author reviews the objective of watershed research at the Coweeta Hydrologic Laboratory and discusses the effects on water yield of clearing and cultivating steep forest lands, of complete removal of forest trees, of woodland grazing, and of logging and burning watersheds.

Hursh, C.R. 1949. Climatic factors controlling roadside design and development. National Research Council Magazine.

Abstract
Factors which influence the revegetation of roadbanks--drying by wind, soil temperatures, frost action, mulching, and road design--are discussed.

Hursh, C.R. 1951. Research in forest-streamflow relations. UNASYLVA 5: 2-9.

Abstract
The objectives of the research program at the Coweeta Hydrologic Laboratory are defined, and current watershed studies are described. The practical significance of research findings in the management of watershed resources is discussed.

Hursh, C.R. 1951. Watershed Aspects of the New York Water Supply Problems. Journal of Forestry. 49(9): 442-444.

Abstract
We are interested in New York's watersheds, not only because they belong to one of the greatest surface water supply systems in the world but also because they furnish examples of all the varied watershed problems that are encountered in the eastern United States. On every drainage area there is to be found both private and public land. The land use ranges from highly improved dairy farms to state park and forest preserves, and these occur over a wide variety of topography and geology. Forest conservation measures carried out in the past have definitely contributed to the development and protection of the New York watersheds. However, additional measures are needed at present because of new problems that are constantly arising.

Hursh, C.R. 1952. Now is the time. Farmers Federation News 32(7): 12.

Abstract
Owners of idle land are urged to initiate conservation measures. The value of trees for protection against erosion, stream sedimentation, and local floods is emphasized.

Hursh, C.R. 1952. Water from the family spring. Living Wilderness 16(39): 11-12.

Abstract
The part a spring plays in rural family life is described.

Hursh, C.R., and C.A. Connaughton. 1938. Effects of forests upon local climate. Journal of Forestry 36: 864-866.

Abstract
Early studies of the effects of forests on climate as authorized in the United States under the McSweeney-McNary Forest Research Act of 1928 are described. Indications are that forests exert little influence on climate of large areas but have a marked effect on local or environmental climate. Observations were made at Copper Basin, a 7,000-acre area completely denuded by smelter fumes, and in the adjacent hardwood forest. The information obtained on microclimate has application in studies of fire, shelter-belts, forest management, and watershed management.

Hursh, C.R., and F.W. Haasis. 1931. Effects of 1925 summer drought on Southern Appalachian hardwoods. Ecology 12: 380-386.

Abstract
Total rainfall recorded at Asheville, N.C., from May to August 1925 was 5.11 inches, whereas the normal is 15.97 inches. Trees on ridges and upper slopes between 2,100 and 2,600 feet elevation became wholly or partially brown during August and September, and some species (chiefly oaks and shortleaf and pitch pines) experienced premature leaf fall. Leaf browning and early fall were more pronounced on younger trees and were particularly severe on dogwood, sourwood, and chestnut. Chestnut oaks and pine survived on areas where black oaks were completely killed.

Hursh, C.R., and G.W. Craddock. 1949. Review on book Hydrology by C. O. Wisler and E. F. Brater. Journal of Forestry 47: 844- 845.

Abstract
As the citation indicates.

Hursh, C.R., and H.C. Pereira. 1953. Field moisture balance in the Shimba Hills, Kenya. East Africa Agricultural Journal 18(4): 1-7.

Abstract
This article draws on limited observations and field measurements to reconstruct and compare the moisture balance of the grass-covered and depleted Shimba Hills of Kenya with that under a natural forest. The natural forest, which once occupied the Shimba Hills, is a more desirable cover than grass for maximum-sustained water yield because water additions from mist and dew are greater from the forest.

Hurtzler, R.A. 1939. Engineering Aspects of the Influence of Forests on Mountain Streams. Civil Engineering. A39: 487-489.

Abstract
In progress at the Appalachian Forest Experiment Station, near Asheville, NC, is a comprehensive investigation of the influence of forests on mountain streams. The objectives and methods of these studies, and some of the results to date, are outlined in the accompanying article. Of particular interest are the descriptions of the special stream-gaging devices, the data on the degree of stream control afforded by forest cover, and the conclusions in regard to infiltration capacity of forest soils.

Huryn, A D. 1985. A new species of Hydroptila (Trichoptera: Hydroptilidae) from North Carolina. Proceedings of the Entomology Society of Washington 87: 444-447.

Abstract
Adult specimens of a previously unknown member of the tineodes species group of Hydroptila, were reared from pupae collected from a high elevation catchment. The male, female and terminal instar larva of Hydroptila coweetensis n. sp. are described and available biological information is given.

Huryn, A.D. 1990. Growth and boltinism of lotic midge larvae: patterns across an Appalachian Mountain landscape. Limnology and Oceanography 35: 334-351.

Abstract
The influence of thermal regime upon community-level growth rates and voltinism was estimated for larval Chironomidae inhabiting litter accumulations in four streams located in an Appalachian Mountain basin.

Huryn, A.D., and J.B. Wallace. 1985. Life history and production of Goerita semata Ross (Trichoptera: Limnephilidae) in the southern Appalachian Mountains. Canadian Journal of Zoology 63: 2604-2611.

Abstract
Populations of Goerita semata are restricted to moss- or liverwort-covered rock faces located in small, heavily shaded high-elevation streams. The larval developmental period was completed in about 655 days with two distinct cohorts being present at any time. Growth was slow, averaging only 0.71% ash-free dry mass per day. In spite of low growth rates, relatively high production was maintained by high larval densities. Production in the rock-face habitat was 237.66 mg ash-free dry mass x m2 x year. Most growth occurred during the spring and was correlated with increases in water temperature and in diatom consumption by the larvae. During the spring, diatoms composed about 64% of the foregut contents. In contrast, amorphous detritus constituted about 91, 65, and 86% of the gut contents during the fall, winter, and summer, respectively. Diatom consumption was estimated to be responsible for 58% of the annual production.

Huryn, A.D., and J.B. Wallace. 1986. A method for obtaining in situ growth rates of larval Chironomidae (Diptera) and its application to studies of secondary production. Limnology Oceanography 31(1): 216-222.

Abstract
Methods and growth chambers are described which permit in situ estimates of the growth rates of chironomid larvae inhabiting litter accumulations in lotic habitats. Instantaneous growth rates (IGRs) for larvae of different sizes ranged from 0.01 to 0.24 mg/mg ash-free dry mass/d at stream temperatures of 2.9 - 15.1C. IGRs were significantly and linearly related to temperature. Regression equations relating IGRs and temperature, combined with field-derived data for chironomid standing stock and stream temperature, enabled calculation of the production of chironomids inhabiting litter accumulations in a temperate mountain stream. The annual production per litter bag was about 224 mg AFDM/yr and the annual P:B was 42, indicating rapid turnover of chironomid biomass. The annual production of chironomids exceeded the mean standing crop biomass of all macroinvertebrates by 4.6 x.

Huryn, A.D., and J.B. Wallace. 1987. Local geomorphology as a determinant of macrofaunal production in a mountain stream. Ecology 68(6): 1932-1942.

Abstract
Local geomorphology determined the diversity and spatial distribution of bedrock-outcrops, riffles, and pools in an Appalachian mountain stream. In turn, the functional structure of the macrofauna was the result of the relative contributions of each habitat type. By replicated monthly sampling, substrate particle size distributions, current velocity, standing crops of benthic organic matter, and production of macrofauna were measured in each of three principal habitats. The bedrock-outcrop habitat was characterized by high material entrainment and export as indicated by significantly higher current velocities and lower standing crops of detritus compared to the riffle and pool habitats. Pools were sites of low entrainment and high retention of organic matter as demonstrated by significantly lower current velocities and higher accumulations of detritus than other habitats. The riffle habitat was intermediate to the bedrock-outcrop and pool habitats in all parameters measured.

Huryn, A.D., and J.B. Wallace. 1987. Production and litter processing by crayfish in an Appalachian Mountain stream. Freshwater Biology 18: 277-286.

Abstract
Mean annual density and biomass of Cambarus bartonii in a mountain stream was 12 individuals/m2 and 1669 mg/m2. While C. bartonii constituted 61% of the total macroinvertebrate biomass, it contributed only 13% of annual community secondary production. Litter processing was positively related to temperature and crayfish size. We speculate that during summer, crayfish play an important role in temperate woodland streams by converting slowly processed leaf litter species (e.g. Rhododendron) to fine particles which are then available to collector-gatherers.

Huryn, A.D., and J.B. Wallace. 1987. The Exopterygote insect community of a mountain stream in North Carolina, USA: Life histories, production, and functional structure. Aquatic Insects 9(4): 229-251.

Abstract
Life histories and production of the Exopterygota inhabiting a first to second order mountain stream were studied by replicated monthly sampling of three different habitats. Production was distributed evenly among four functional groups with collector-gatherers, shredders, scrapers, and engulfing- predators contributing 21%, 33%, 23%, and 23%, respectively. Annual production by the Exopterygota was greatest in the boulder-outcrop habitat. Sixty-five percent of production was based on a collector-gatherer, but this group constituted only 2% and 8% of pool and riffle production. Comparison of the functional structure of the exopterygote communities of headwaters with higher order streams indicated a shift from a dominance of detritivory to predation.

Huryn, A.D., and J.B. Wallace. 1988. Community structure of Tricoptera in a mountain stream: spatial patterns of production and functional organization. Freshwater Biology 20: 141-155.

Abstract
Annual production was estimated for Trichoptera occurring in three stream habitats of WS 27. Production was greatest on bedrock-outcrops, followed by riffles and pools. Annual production in bedrock-outcrops and pools was dominated by single functional groups, collector-filterers and shredders respectively. Production in riffles was due to a combination of shredders and collector-filterers. Habitat-weighted production was distributed among functional groups: collector-filterers (41%), shredders (29%), engulfing-predators (15%), scrapers (13%), and collector-gatherers (2%). The distinct taxonomic and functional structures of trichopteran sub-communities were shaped by the physical characteristics of their principal habitats.

Huryn, A.D., and J.B. Wallace. 2000. Life History And Production Of Stream Insects. Annual Reviews Entomology. 45: 83-110.

Abstract
Studies of the production of stream insects are now numerous, and general factors controlling the secondary production of stream communities are becoming evident. In this review we focus on how life-history attributes influence the production dynamics of stream insects and other macroinvertebrates. Annual production of macroinvertebrates communities in streams world-wide ranges from approximately 10+ to 103 g dry mass m -2. High levels are reported for communities dominated by filter feeders in temperate streams. Filter feeding enables the accrual and support of high biomass, which drives the very highest production. Frequently disturbed communities in warm-temperate streams are also highly productive. Biomass accrual by macroinvertebrates is limited in these streams, and production is driven by rapid growth rates rather than high biomass. The lowest production, reported for macroinvertebrate communities of cool-temperate and arctic streams, is due to the constraints of low seasonal temperatures and nutrient or food limitation. Geographical bias, paucity of community-wide studies, and limited knowledge of the effects of biotic interactions limit current understanding of mechanisms controlling stream productivity.

Hutchens, J.J. Jr., and E.F. Benfield. 2000. Effects of Forest Defoliation by the Gypsy Moth on Detritus Processing in Southern Appalachian Streams. The American Midland Naturalist. 143: 397-404.

Abstract
We investigated whether changes in chestnut oak (Quercus prinus L.) leaf quality caused by gypsy moth (Lymantria dispar L.) defoliation affected leaf breakdown rates in southern Appalachian streams of differing disturbance history. Breakdown rats of secondflush leaves produced after defoliation were compared to those of natural spring-flush leaves shed in autumn. Second-flush leaves broke down significantly faster than spring-flush leaves in three of the six streams tested. Initial fiber content and the ratio of fiber to protein were significantly higher in spring-flush leaves than in second-flush leaves, showing that initial differences in internal leaf constituents could explain the faster breakdown rates of secondflush leaves. Using changes in leaf toughness through time as a measure of microbial conditioning we found that the faster-decaying second-flush leaves also softened at a faster rate than the spring-flush leaves. In addition, both types of leaves incubated in three streams draining a recovering 14-y-old clear-cut catchment broke down significantly faster than leaves incubated in three streams draining a reference catchment. We attributed this increase in leaf breakdown to significantly higher abundance and density of leaf-shredding insects and greater microbial conditioning in leaf packs in the streams of the recovering clear-cut catchment. Overall, our results show that insect defoliation accelerates detritus processing in southern Appalachian streams and that this acceleration may be especially important in previously disturbed streams in which leaves are already processed faster.

Hutchens, J.J. Jr., and J.B. Wallace. 2002. Ecosystem Linkages between Southern Appalachian Headwater Streams and Their Banks: Leaf Litter Breakdown and Invertebrate Assemblages. Ecosystems. 5: 80-91.

Abstract

We examined red maple (Acer rubrum L.) leaf litter breakdown in streams and riparian zones at two sites in the southern Appalachian Mountains to understand how differences in abiotic and biotic factors influence leaf breakdown rates. Litterbags were placed in three riparian habitats differing in litter layer moisture: stream > bank > upland. Invertebrates colonizing litterbags at one site were also examined to determine how variations in community and functional structure affect breakdown rates. Leaves broke down fastest in streams and slowest in upland habitats, whereas bank habitats were intermediate and characterized by high variability. Faster leaf breakdown rates in streams appeared to be a function of greater moisture availability, a more stable thermal regime, and a higher biomass of leaf-shredding invertebrates, especially the stonefly Tallaperia. In addition, patterns of leaf breakdown and invertebrate community structure provided evidence for a stronger than expected ecological connection between the stream and the bank. Overall, detritus processing within this narrow riparian ecosystem varied considerably depending on the availability of moisture. Results from this study show that stream channel-flood-plain interactions in riparian ecosystems of steep forested mountains are analogous to ones in larger downstream or low-gradient systems. Riparian zones throughout a river network display a remarkable heterogeneity in their ability to process organic matter, which is ultimately driven by changes in hydrological conditions.

Hutchens, J.J. Jr., E.F. Benfield, and J.R. Webster. 1997. Diet and growth of a leaf-shredding caddisfly in southern Appalachian streams of contrasting disturbance history. Hydrobiologia. 346: 193- 201.

Abstract
Diet and growth of leaf-shredding caddisfly larvae, Pycnopsyche spp., were examined in streams draining a reference catchment and a 16-year- old clear-cut (disturbed) catchment at Coweeta Hydrologic Laboratory in southwestern North Carolina, USA. The objective was to explain why shredder production is higher in the disturbed streams despite the larvae having less food available. We predicted larvae would grow faster on fast-decaying leaf material representative of the disturbed streams. Larvae consumed mostly leaf detritus in three streams drain- ing each catchment over three seasons, which showed larvae did not consume higher quality foods in disturbed streams. When fed 2-month- old conditioned black birch and white oak leaves in the laboratory, larvae grew significantly faster on the birch leaves. However, when larvae were fed the same leaf types after 3-months conditioning, larvae grew significantly faster on oak leaves. A field growth experiment conducted for 42 d using mixed-species leaf diets repre- sentative of each catchment and initially conditioned for 2 months found that Pycnopsyche grew significantly better on the diet repre- sentative of the reference catchment. The reference diet contained more oak leaves which apparently became a more acceptable food as the experiment proceeded. High shredder production in the disturbed streams could not be explained by high Pycnopsyche growth rates on fast-decaying leaves. Instead, larvae grew better on leaves that were apparently conditioned optimally regardless of conditioning rate.

Hutchens, J.J. Jr., J.B. Wallace, and E.D. Romaniszyn. 2005. Role of Podostemum ceratophyllum Michx. in structuring benthic macroinvertebrate assemblages in a southern Appalachian river. Journal of the North American Benthological Society. 23(4): 713-727.

Abstract
Podostemum ceratophyllum Michx. has been associated with extremely high secondary production of benthic macroinvertebrates in open-canopy rapids. We conducted an experiment in the 7th-order Little Tennessee River, North Carolina, to test whether varying amounts of Podostemum influenced macroinvertebrate abundance, biomass, community composition, and functional feeding group structure. The experiment consisted of 3 treatments in which P. ceratophyllum was completely, partially, or not removed from portions of 4 bedrock outcrops at 2 sites. Macroinvertebrates were sampled at 0, 3, and 6 wk post treatment. Complete removal of P. ceratophyllum greatly reduced overall macroinvertebrate abundance and biomass and altered assemblage structure, but had relatively little effect on functional structure. The lack of change in functional feeding group structure was probably a result of the importance of P. ceratophyllum as a substrate for epiphytic algae, and the availability of nearby colonists in undisturbed habitats. We found a strong positive relationship between surface area of Podostemum and total macroinvertebrate abundance and biomass. We estimated that P. ceratophyllum increased surface area by 3 to 4 times over bare bedrock. Podostemum ceratophyllum in the Little Tennessee River serves as an important habitat supporting high abundance and biomass of macroinvertebrates.

Hutchens, J.J. Jr., K. Chung, and J.B. Wallace. 1998. Temporal variability of stream macroinvertebrate abundance and biomass following pesticide disturbance. Journal of the North American Benthological Society. 17(4): 518-534.

Abstract
We determined the extent of macroinvertebrate recovery in a former pesticide-treated stream (FTS) relative to a reference stream (RS) by examining macroinvertebrates colonizing red maple (Acer rubrum L.) litter bags between 5 to 10 y following pesticide treatment. Mean abundance and biomass, variability in abundance and biomass (using the coefficient of variation [CV]), and assemblage structure were compared both within and among years to assess recovery. The 5 y of study included 3 drought years followed by 2 wet years. Mean total abundance and biomass of macroinvertebrates, and that of most functional feeding groups (FFG) did not significantly differ between streams during this study, nor did within-year variability of these means, indicating macroinvertebrates in FTS had recovered relative to RS. Some exceptions to the above patterns resulted from the dynamics of a single taxon in each group. Macroinvertebrate assemblage structure in litter bags was similar between streams throughout the study as shown by their similar ordination scores; hence, assemblage structure had also recovered. In each stream, mean annual abundance and biomass of total macroinvertebrates and of each FFG, aside from shredder abundance, differed significantly among years. However, assemblage structure was generally similar among years. Among-year CVs were usually lower than within-year CVs because macroinvertebrate abundance and biomass fluctuated more during a year than it did from year to year, and different processes apparently contributed to the variation observed at these 2 time scales. For example, juvenile development time influenced within-year CVs, indicating that life-history characteristics affected temporal variability of macroinvertebrate abundance and biomass. Examination of both the means and their variances was useful for determining the extent of recovery and how macroinvertebrates responded to natural environmental variability. The detailed analysis of temporal dynamics at different time scales afforded by the CV supported our contention that FTS had recovered from the pesticide application relative to RS.

Hutchins, Matthew. 2007. Effects of a prescribed burn on soil microarthropod populations at Nancytown, GA. UNCA Journal of undergraduate research. 74-80.

Abstract
In this study, the effects of a low-intensity prescribed burn were assessed on soil microarthropods by examining Collembola, Oribatid, Mesostigmata, and Prostigmata populations. Sampling was done for three consecutive years, including one year pre-burn. Mean microarthropod populations of all groups fluctuated over the three years, but further analysis indicated significant differences by date with population increases in 2006 for only Collembola and Oribatid populations.

Hwang, T., Band, L., Hales, T. Ecosystem processes at the watershed scale: Extending optimality theory from plot to catchment. Water Resources Research, 45: W11425.

Abstract
The adjustment of local vegetation conditions to limiting soil water by either maximizing productivity or minimizing water stress has been an area of central interest in ecohydrology since Eagleson’s classic study. This work has typically been limited to consider one-dimensional exchange and cycling within patches and has not incorporated the effects of lateral redistribution of soil moisture, coupled ecosystem carbon and nitrogen cycling, and vegetation allocation processes along topographic gradients. We extend this theory to the hillslope and catchment scale, with in situ and downslope feedbacks between water, carbon and nutrient cycling within a fully transient, distributed model. We explore whether ecosystem patches linked along hydrologic flow paths as a catena evolve to form an emergent pattern optimized to local climate and topographic conditions. Lateral hydrologic connectivity of a small catchment is calibrated with streamflow data and further tested with measured soil moisture patterns. Then, the spatial gradient of vegetation density within a small catchment estimated with fine-resolution satellite imagery and field measurements is evaluated with simulated vegetation growth patterns from different root depth and allocation strategies as a function of hillslope position. This is also supported by the correspondence of modeled and field measured spatial patterns of root depths and catchmentlevel aboveground vegetation productivity.We test whether the simulated spatial pattern of vegetation corresponds to measured canopy patterns and an optimal state relative to a set of ecosystem processes, defined as maximizing ecosystem productivity and water use efficiency at the catchment scale. Optimal carbon uptake ranges show effective compromises between multiple resources (water, light, and nutrients), modulated by vegetation allocation dynamics along hillslope gradient.

Hwang, T., Band, L.E., Hales, T.C., Miniat, C.F., Vose, J.M., Bolstad, P.V., Miles, B. and Price, K. 2015. Simulating vegetation controls on hurricane-induced shallow landslides with a distributed ecohydrological model. Journal of Geophysical Research: Biosciences. 120(2):361-378. (DOI: 10.1002/2014JG002824)

Abstract
The spatial distribution of shallow landslides in steep forested mountains is strongly controlled by aboveground and belowground biomass, including the distribution of root cohesion. While remote sensing of aboveground canopy properties is relatively advanced, estimating the spatial distribution of root cohesion at the forest landscape scale remains challenging. We utilize canopy height information estimated using lidar (light detecting and ranging) technology as a tool to produce a spatially distributed root cohesion model for landslide hazard prediction. We characterize spatial patterns of total belowground biomass based on the empirically derived allometric relationship developed from soil pit measurements in the Coweeta Hydrologic Laboratory, North Carolina. The vertical distribution of roots and tensile strength were sampled at soil pits allowing us to directly relate canopy height to root cohesion and use this model within a distributed ecohydrological modeling framework, providing transient estimates of runoff, subsurface flow, soil moisture, and pore pressures. We tested our model in mountainous southern Appalachian catchments that experienced a number of landslides during the 2004 hurricane season. Slope stability estimates under the assumption of spatially uniform root cohesion significantly underpredicted both the total number of landslides and the number of “false positives,” unfailed areas of the landscape that were predicted to fail. When we incorporate spatially distributed root cohesion, the accuracy of the slope stability forecast improves dramatically. With the growing availability of lidar data that can be used to infer belowground information, these methods may provide a wider utility for improving landslide hazard prediction and forecasting.

Hwang, T., Band, L.E., Miniat, C.F., Song, C., Bolstad, P.V., Vose, J.M. and Love, J.P. 2014. Divergent phenological response to hydroclimate variability in forested mountain watersheds. Global Change Biology. 20:2580-2595. (DOI:10.1111/gcb.12556)

Abstract
Mountain watersheds are primary sources of freshwater, carbon sequestration, and other ecosystem services. There is significant interest in the effects of climate change and variability on these processes over short to long time scales. Much of the impact of hydroclimate variability in forest ecosystems is manifested in vegetation dynamics in space and time. In steep terrain, leaf phenology responds to topoclimate in complex ways, and can produce specific and measurable shifts in landscape forest patterns. The onset of spring is usually delayed at a specific rate with increasing elevation (often called Hopkins' Law; Hopkins, 1918), reflecting the dominant controls of temperature on greenup timing. Contrary with greenup, leaf senescence shows inconsistent trends along elevation gradients. Here, we present mechanisms and an explanation for this variability and its significance for ecosystem patterns and services in response to climate. We use moderate-resolution imaging spectro-radiometer (MODIS) Normalized Difference Vegetation Index (NDVI) data to derive landscape-induced phenological patterns over topoclimate gradients in a humid temperate broadleaf forest in southern Appalachians. These phenological patterns are validated with different sets of field observations. Our data demonstrate that divergent behavior of leaf senescence with elevation is closely related to late growing season hydroclimate variability in temperature and water balance patterns. Specifically, a drier late growing season is associated with earlier leaf senescence at low elevation than at middle elevation. The effect of drought stress on vegetation senescence timing also leads to tighter coupling between growing season length and ecosystem water use estimated from observed precipitation and runoff generation. This study indicates increased late growing season drought may be leading to divergent ecosystem response between high and low elevation forests. Landscape-induced phenological patterns are easily observed over wide areas and may be used as a unique diagnostic for sources of ecosystem vulnerability and sensitivity to hydroclimate change.

Hwang, T., Band, L.E., Vose, J.M. and Tague, C. 2012. Ecosystem processes at the watershed scale: Hydrologic vegetation gradient as an indicator for lateral hydrologic connectivity of headwater catchments. Water Resources Research. 48. W06514. (DOI: 10.1029/2011WR011301)

Abstract
Lateral water flow in catchments can produce important patterns in water and nutrient fluxes and stores and also influences the long-term spatial development of forest ecosystems. Specifically, patterns of vegetation type and density along hydrologic flow paths can represent a signal of the redistribution of water and nitrogen mediated by lateral hydrologic flow. This study explores the use of emergent vegetation patterns to infer ecohydrologic processes and feedbacks in forested headwater catchments. We suggest a hydrologic gradient of vegetation density as an indicator of lateral connectivity within headwater catchments. We define the hydrologic vegetation gradient (HVG) as the increase of normalized difference vegetation index per unit increase of the topographic wetness index. HVG are estimated in different headwater catchments in the Coweeta Hydrologic Laboratory using summer IKONOS imagery. We use recession slope analysis with gauge data and a distributed ecohydrological model to characterize the patterns of seasonal flow regimes within the catchments. Correlations between HVG, catchment runoff, early recession parameters, and model parameters show the interactive role of vegetation and lateral hydrologic connectivity of systems in addition to climatic and geomorphic controls. This suggests that HVG effectively represents the level of partitioning between localized water use and lateral water flow along hydrologic flow paths, especially during the growing season. It also presents the potential to use simple remotely sensed hydrologic vegetation gradients as an indicator of lateral hydrologic connectivity to extrapolate recession behavior and key model parameters of distributed hydrological models for ungauged headwater catchments.

Hwang, T., C. Song, J.M. Vose, and L.E. Band. 2011. Topography-mediated controls on local vegetation phenology estimated from MODIS vegetation index. Landscape Ecology. DOI: 10.1007/s10980-011-9580-8.

Abstract
Forest canopy phenology is an important constraint on annual water and carbon budgets, and responds to regional interannual climate variation. In steep terrain, there are complex spatial variations in phenology due to topographic influences on microclimate, community composition, and available soil moisture. In this study, we investigate spatial patterns of phenology in humid temperate forest as a function of topography. Moderate-resolution imaging spectroradiometer (MODIS) vegetation indices are used to derive local patterns of topography-mediated vegetation phenology using a simple post-processing analysis and a non-linear model fitting. Elevation has the most explanatory power for all phenological variables with a strong linear relationship with mid-day of greenup period, following temperatures lapse rates. However, all other phenological variables show quadratic associations with elevation, reflecting an interaction between topoclimatic patterns of temperature and water availability. Radiation proxies also have significant explanatory power for all phenological variables. Though hillslope position cannot be adequately resolved at the MODIS spatial resolution (250 m) to discern impacts of local drainage conditions, extended periods of greenup/senescence are found to occur in wet years. These findings are strongly supported by previous field measurements at different topographic positions within the study area. The capability of detecting topography-mediated local phenology offers the potential to detect vegetation responses to climate change in mountainous terrain. In addition, the large, local variability of meteorological and edaphic conditions in steep terrain provides a unique opportunity to develop an understanding of canopy response to the interaction of climate and landscape conditions.

Hwang, Taehee, Conghe Song, Paul V. Bolstad, Lawrence E. Band. 2011. Downscaling real-time vegetation dynamics by fusing multi-temporal MODIS and Landsat NDVI in topographically complex terrain. Remote Sensing of Environment 115(10): 2499-2512. (DOI:10.1016/j.rse.2011.05.010)

Abstract
Canopy phenology is an important factor driving seasonal patterns of water and carbon exchange between land surface and atmosphere. Recent developments of real-time global satellite products (e.g., MODIS) provide the potential to assimilate dynamic canopy measurements with spatially distributed process-based ecohydrological models. However, global satellite products usually are provided with relatively coarse spatial resolutions, averaging out important spatial heterogeneity of both terrain and vegetation. Therefore, bias can result from lumped representation of ecological and hydrological processes especially in topographically complex terrain. Successful downscaling of canopy phenology to high spatial resolution would be indispensable for catchment-scale distributed ecohydrological modeling, aiming at understanding complex patterns of water, carbon and nutrient cycling in mountainous watersheds. Two downscaling approaches are developed in this study to overcome this issue by fusing multi-temporal MODIS and Landsat TM data in conjunction with topographic information to estimate high spatio-temporal resolution biophysical parameters over complex terrain. MODIS FPAR (fraction of absorbed photosynthetically active radiation) is used to provide medium spatial resolution phenology, while the variability of vegetation within a MODIS pixel is characterized by Landsat NDVI. The algorithms depend on the scale-invariant linear relationship between FPAR and NDVI, which is verified in this study. Downscaled vegetation dynamics are successfully validated both temporally and spatially with ground-based continuous FPAR and leaf area index measurements. Topographic correction during the downscaling process has a limited effect on downscaled FPAR products except for the period around the winter solstice in the study area.

Ibanez, I., Clark, J.S., Dietze, M.C. 2008. Evaluating the Sources of Potential Migrant Species: Implications Under Climate Change. Ecological Applications, 18(7): 1664-1678.

Abstract
As changes in climate become more apparent, ecologists face the challenge of predicting species responses to the new conditions. Most forecasts are based on climate envelopes (CE), correlative approaches that project future distributions on the basis of the current climate often assuming some dispersal lag. One major caveat with this approach is that it ignores the complexity of factors other than climate that contribute to a species’ distributional range. To overcome this limitation and to complement predictions based on CE modeling we carried out a transplant experiment of resident and potential-migrant species. Tree seedlings of 18 species were planted side by side from 2001 to 2004 at several locations in the Southern Appalachians and in the North Carolina Piedmont (USA). Growing seedlings under a large array of environmental conditions, including those forecasted for the next decades, allowed us to model seedling survival as a function of variables characteristic of each site, and from here we were able to make predictions on future seedling recruitment. In general, almost all species showed decreased survival in plots and years with lower soil moisture, including both residents and potential migrants, and in both locations, the Southern Appalachians and the Piedmont. The detrimental effects that anticipated arid conditions could have on seedling recruitment contradict some of the projections made by CE modeling, where many of the species tested are expected to increase in abundance or to expand their ranges. These results point out the importance of evaluating the potential sources of migrant species when modeling vegetation response to climate change, and considering that species adapted to the new climate and the local conditions may not be available in the surrounding regions.

Ibanez, I., Clark, J.S., Dietze, M.C. 2009. Estimating colonization potential of migrant tree species. Global Change Biology. 15: 1173-1188

Abstract
Plant populations migrating in response to climate change will have to colonize established communities. Even if a population disperses to a new region with a favorable climate, interactions with other species may prevent its establishment and further spread. The potential of these species to grow along with residents will be a critical factor controlling their response to climate change. To determine the capacity of migrating species to colonize established communities we conducted extensive long-term transplant experiments where potential tree migrant species, i.e. species within ‘migration range,’ were planted side by side with resident ones. Potential immigrants were selected to be representative species of their native communities. For both groups, residents and potential migrants (17 species), we compared their growth response along gradients in soil moisture and light availability. Rather than manipulate climate directly, we exploited natural microclimatic gradients and the fluctuations in climate that occurred during the 5-year experiment. Experimental results were used to estimate growth in the context of novel climate and relevant establishment factors. Results suggest that potential immigrant species had similar growth rates in the new environment than those from resident species ensuring their ability to establish in the area. However, contrary to our expectations, the soil moisture requirements for the immigrant group were similar to those of the resident species. These results could have major implications for vegetation changes under the predicted drier climate for the region. If it is the case that neither resident species nor potential migrants are able to maintain stable populations, the region may experience a decline in local biodiversity.

Ibanez, I., J.S. Clark, S. LaDeau, and J. Hille Ris Lambers. 2007. Exploiting temporal variability to understand tree recruitment response to climate change. Ecological Monographs. 77(2): 163-177.

Abstract
 Predicting vegetation shifts under climate change is a challenging endeavor, given the complex interactions between biotic and abiotic variables that influence demographic rates. To determine how current trends and variation in climate change affect seedling establishment, we analyzed demographic responses to spatiotemporal variation to temperature and soil moisture in the southern Appalachian Mountains. We monitored seedling establishment for 10 years in five plots located along an elevational gradient of five dominant tree species: Acer rubrum, Betula spp., Liriodendron tulipifera, Nyssa sylvatica, and Quercus rubra. A hierarchical Bayes model allowed us to incorporate different sources of information, observation errors, and the inherent variability of the establishment process. From our analysis, spring temperatures and heterogeneity in soil moisture emerge as key drivers, and they act through nonlinear population demographic processes.

Ives, A.R., M.G. Turner, and S.M. Pearson. 1998. Local explanations of landscape patterns: can analytical approaches approximate simulation models of spatial processes? Ecosystems. 1: 35-51.

Abstract
Research over the last 100 years has demonstrated the importance of space for ecological processes. Given this importance, it may seem natural to start investigations into broad-scale ecological processes with a comprehensive, broad-scale spatial map. Here we argue that it may sometimes be possible to answer important questions about spatial processes using crude spatial information obtained when a comprehensive map is not available. To present our argument, we first develop a simple simulation model for a perennial plant reproducing and dying on a landscape with different arrangements of suitable and unsuitable sites. We them develop a simple, analytical approximation to predict the fraction of suitable sites that are occupied by the simulated plants. The analytical approximation summarizes the spatial map by using a single parameter that gives the probability that a site adjacent to a suitable site is suitable. Comparing the predictions of both approaches highlights three points: (a) The role of the spatial environment in ecological processes may play out at the local scale. Therefore, studying the local-scale processes may provide insights into landscape patterns. (b) The predictions from the analytical approximation fail noticeably when suitable sites are rare and are distributed randomly (rather than clumped) on the map. In these situations, patches of interconnected suitable sites are very small, and populations within small patches may go extinct via demographic stochasticity. This illustrates how analytical approximations can be used to identify cases when local-scale spatial processes are not sufficient to understand the ecological consequences of space. (c) For many natural systems, constructing the appropriate environmental map needed to study ecological processes is difficult or impossible. However, summary characteristics such as those employed by the analytical approximation may be estimated directly in nature. Therefore, even in the absence of an explicitly spatial broad-scale map, it may be possible to study spatial processes by understanding which local-scale characteristics of space are important.

J. Bruce Wallace, Susan L. Eggert, Judy L. Meyer, and Jackson R. Webster 2015. Stream invertebrate productivity linked to forest subsidies: 37 stream-years of reference and experimental data. Ecology 96:1213-1228. http://dx.doi.org/10.1890/14-1589.1

Abstract
Riparian habitats provide detrital subsidies of varying quantities and qualities to recipient ecosystems. We used long-term data from three reference streams (covering 24 stream-years) and 13-year whole-stream organic matter manipulations to investigate the influence of terrestrial detrital quantity and quality on benthic invertebrate community structure, abundance, biomass, and secondary production in rockface (RF) and mixed substrates (MS) of forested headwater streams. Using a mesh canopy covering the entire treatment stream, we examined effects of litter exclusion, small- and large-wood removal, and addition of artificial wood (PVC) and leaves of varying quality on organic matter standing crops and invertebrate community structure and function. We assessed differences in functional feeding group distribution between substrate types as influenced by organic matter manipulations and long-term patterns of predator and prey production in manipulated vs. reference years. Particulate organic matter standing crops in MS of the treatment stream declined drastically with each successive year of litter exclusion, approaching zero after three years. Monthly invertebrate biomass and annual secondary production was positively related to benthic organic matter in the MS habitats. Rockface habitats exhibited fewer changes than MS habitats across all organic matter manipulations. With leaf addition, the patterns of functional group distribution among MS and RF habitats returned to patterns seen in reference streams. Secondary production per unit organic matter standing crop was greatest for the leaf addition period, followed by the reference streams, and significantly less for the litter exclusion and wood removal periods. These data indicate that the limited organic matter remaining in the stream following litter exclusion and wood removal was more refractory than that in the reference streams, whereas the added leaf material was more labile and readily converted into invertebrate production. Predator production and total production were tightly coupled in reference and treatment streams, indicating strong relationships between predators and their prey. Results from the artificial wood addition demonstrate that physical structure alone will not restore invertebrate productivity without detrital resources from the riparian forest. Our long-term studies conducted over three decades at the ecosystem scale unequivocally show the necessity of maintaining and restoring aquatic–terrestrial linkages in forested headwater streams.

J.S. Norman, J.E. Barrett. 2013. Substrate and nutrient limitation of ammonia-oxidizing bacteria and archaea in temperate forest soil. Soil Biology & Biochemistry 69:141-146.

Abstract
Ammonia-oxidizing microbes control the rate-limiting step of nitrification, a critical ecosystem process, which affects retention and mobility of nitrogen in soil ecosystems. This study investigated substrate (NH4þ) and nutrient (K and P) limitation of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in temperate forest soils at Coweeta Hydrologic Laboratory, a long-term ecological research site in western North Carolina, USA. We investigated substrate and nutrient limitation by amending soils with either ammonium or a nutrient solution containing P and K, then assessing the growth of these organisms during in situ soil incubations. We found substantial growth of both AOA and AOB during all incubations including unamended control incubations. Our results demonstrate that substrate availability limits nitrification by AOB and that high levels of substrate addition inhibit the growth of AOA in these soils. We found no evidence for nutrient limitation of AOB, though nutrient addition indirectly stimulated nitrification by AOB through increased nitrogen mineralization. Our data did suggest nutrient limitation by AOA, though it is unclear whether AOA significantly contribute to ammonia oxidation in this system. Furthermore, we show that AOB are responsible for the majority of ammonia oxidation in high substrate, high nutrient conditions.

Jackson CR, Webster JR, Knoepp JD, et al. Unexpected ecological advances made possible by long-term data: A Coweeta example. WIREs Water. 2018;e1273. https://doi.org/10.1002/wat2.1273

Abstract
In the 1970s, Forest Service and academic researchers clearcut the forest in Watershed 7 in the Coweeta Basin to observe how far the perturbation would move the ecosystem and how quickly the ecosystem would return to its predisturbance state. Our long-term observations demonstrated that this view of resistance and resilience was too simplistic. Forest disturbance triggered a chain of ecological dynamics that are still evolving after 40?years. Short-term pulses in dissolved inorganic nitrogen (DIN) (3?years) and streamflows (4?years) were followed by several years in which the system appeared to be returning to predisturbance conditions. Then however, changes in forest composition triggered a regime change in DIN dynamics from biological to hydrological control as well as persistent high stream DIN levels mediated by climatic conditions. These forest composition changes also led to later reductions in streamflow. These long-term observations of streamflows, stream DIN concentrations, stream DIN exports, and stand composition have substantially advanced our understanding of forest ecosystem dynamics; and they demonstrate the value of long-term observational data in revealing ecosystem complexities and surprises, generating new hypotheses, and motivating mechanistic research. Shorter observational records from this experiment would have produced incomplete or erroneous inference.

Jackson, C. R. and C. M. Pringle. Ecological Benefits of Reduced Hydrologic Connectivity in Intensively Developed Landscapes. BioScience, 60(1): 37-46

Abstract
A broad perspective on hydrologic connectivity is necessary when managing stream ecosystems and establishing conservation priorities. Hydrologic connectivity refers to the water-mediated transport of matter, energy, or organisms within or between elements of the hydrologic cycle. The potential negative consequences of enhancing hydrologic connectivity warrant careful consideration in human-modified landscapes that are increasingly characterized by hydrologic alteration, exotic species, high levels of nutrients and toxins, and disturbed sediment regimes. While connectivity is integral to the structure and function of aquatic ecosystems, it can also promote the distribution of undesirable components. Here we provide examples illustrating how reduced hydrologic connectivity can provide greater ecological benefits than enhanced connectivity does in highly developed, human-modified ecosystems; for example, in urban landscapes, “restoration” efforts can sometimes create population sinks for endangered biota.We conclude by emphasizing the importance of adaptivemanagement and balancing trade-offs associated with further alterations of hydrologic connectivity in human-modified landscapes.

Jackson, C. R., Leigh, D. S., Scarbrough, S. L., and Chamblee, J. F. 2015. Herbaceous Versus Forested Riparian Vegetation: Narrow and Simple Versus Wide, Woody and Diverse Stream Habitat. River Res. Applic., 31: 847-857. doi: 10.1002/rra.2783.

Abstract
We investigated interactions of riparian vegetative conditions upon a suite of channel morphological variables: active channel width, variability of width within a reach, large wood frequency, mesoscale habitat distributions, mesoscale habitat diversity, median particle size and per cent fines. We surveyed 49 wadeable streams, 45 with low levels of development, throughout the Upper Little Tennessee River Basin in the Southern Appalachians. Conversion of riparian forest to grass has reduced aquatic habitat area (quantified by active channel width), channel width variability, wood frequency, mesoscale habitat diversity and obstruction habitat (wood and rock jams), and such conversion has increased the fraction of run and glide habitat. Channels with grassy riparian zones were only one-third to three-fifths of the width of channels with forested riparian zones, and channels with grassy or narrow forested riparian zones were nearly devoid of wood. Particle size metrics were strongly affected by stream power and agricultural cover in the basin, but the data suggest that elimination of riparian forest reduces median bed particle size. Results indicate that even modest increases in the extent and width of forested riparian buffers would improve stream habitat conditions.

Jackson, C. Rhett, Robert A. Bahn, and Jackson R. Webster, 2017. Water Quality Signals from Rural Land Use and Exurbanization in a Mountain Landscape: What’s Clear and What’s Confounded? Journal of the American Water Resources Association (JAWRA) 53(5):1212-1228. https://doi.org/10.1111/1752-1688.12567

Abstract
The overall influence of urbanization on how flows of different frequency might change over time, while important in hydrologic design, remains imprecisely known. In this study, we investigate the effects of urbanization on flow duration curves (FDCs) and flow variability through a case study of eight watersheds that underwent different amounts of growth, in the Puget Sound region in Western Washington State, United States. We computed annual FDCs from flow records spanning 1960-2010 and, after accounting for the effects of precipitation, we conducted statistical trend analyses on flow metrics to quantify how key FDC percentiles changed with time in response to urbanization. In the urban watersheds, the entire FDC tended to increase in magnitude of flow, especially the 95th-99th percentile of the daily mean flow series, which increased by an average of 43%. Stream flashiness in urban watersheds was found to increase by an average of 70%. The increases in FDC magnitude and flashiness in urbanizing watersheds are most likely a result of increasing watershed imperviousness and altered hydrologic routing. Rural watersheds were found to have decreasing FDC magnitude over the same time period, which is possibly due to anthropogenic extractions of groundwater, and increasing stream flashiness, which is likely a result of reductions in base flow and increasing precipitation intensity and variability.

Jackson, C.R., Bitew, M. and Du, E. 2014. When interflow also percolates: Downslope travel distances and hillslope process zones. Hydrological Processes. 28:3195-3200. (DOI: 10.1002/hyp.10158)

Jackson, C.R., W.T. Swank, and R. Olszeewski. 2005. John D. Hewlett (1992-2004). Transaction AGU. 8612: 124.

Abstract
John D. Hewlett, a pioneer in forest and hillslope hydrology, passed away on 19 July 2004 in Athens, Georgia, where he had retired after a distinguished career with the University of Georgia and the United States Forest Service. Hewlett helped transform our views of catchment hydrology through his development of the variable source area model of streamflow generation from forested catchments and the interflow model of base flow sustenance in mountainous environments. Hewlett was born on 29 March 1922 in Philadelphia, Pennsylvania, and was reared in the Shenandoah Valley of Virginia. He entered military service in 1942 and served in the European Theater of World War II until the end of the war. He earned his bachelor¼s degree in forestry from New York State College of Forestry in Syracuse in 1949 and a master of science degree in forest ecology from Syracuse University in 1956. In 1960, he obtained a doctorate degree from Duke University, Durham North Carolina, with an emphasis on plant water physiology.

Jackson, M.M., Pearson, S.M. and Turner, M.G. 2013. Performance and population dynamics of a native understory herb differ between young and old forest stands in the Southern Appalachians. Forest Ecology and Management. 304:444-454. (DOI: 10.1016/j.foreco.2013.05.049)

Abstract
Anthropogenic disturbances (e.g., logging) can strongly affect the composition and structure of forest understory herb communities, with land-use legacies often persisting for decades or even centuries. Many studies of forest plant response to land-use history have focused on species distributions and abundances, and argued broadly for either dispersal or establishment limitation as biological mechanisms for slow recolonization. We asked how performance and population dynamics of the temperate forest herb Prosartes lanuginosa differed between recently logged (20�“40 years ago) and old (>90 years) logged forests in the Southern Appalachians, USA. All stands were well developed with canopy closure ranging from 59�“90%. Performance of individual plants (N = 859) was monitored over three years across 19 forest stands (N = 9 recent and 10 old). We also conducted a seed sowing experiment to determine whether germination and establishment differed with stand age. Stage-based matrix models and life table response experiments (LTREs) were used to quantify the contributions of each life-history transition to observed differences in population growth rates (λ) across stands and between years. Field measurements revealed that population growth rates were higher in older logged stands (λ = 0.78�“0.84) than in more recently logged stands (λ = 0.68�“0.74), primarily because of reduced fecundity and reduced recruitment from vegetative to flowering life stages. Seed germination and seedling survival did not differ between old and young logged forests. Across stands, population growth rates were higher during the first annual transition than the second, which followed a drought spring. However, the mechanisms for these differences in λ varied with stand age; populations in old forests responded to drought conditions by lowering fecundity, whereas populations in young forests responded with lower recruitment from vegetative to flowering stages. Our results showed that logging history affects plant performance beyond the establishment phase and interacts with environmental conditions to influence population dynamics. Our results also emphasize the need for multiple performance measures to assess the effects of land-use history on forest plants.

Jackson, M.M., Turner, M.G. and Pearson, S.M. 2014. Logging legacies affect insect pollinator communities in southern Appalachian forests. Southeastern Naturalist. 13(2):317-336. (DOI: http://dx.doi.org/10.1656/058.013.0213)

Jackson, M.M., Turner, M.G., Pearson, S.M. and Ives, A.R. 2012. Seeing the forest and the trees: multilevel models reveal both species and community patterns. Ecosphere. 3(9). (DOI: http://dx.doi.org/10.1890/ES12-00116.1)

Abstract
Studies designed to understand species distributions and community assemblages typically use separate analytical approaches (e.g., logistic regression and ordination) to model the distribution of individual species and to relate community composition to environmental variation. Multilevel models (MLMs) offer a promising strategy for integrating species and community-level analyses. Here, we demonstrate how MLMs can be used to analyze differences in species composition of communities across environmental gradients. We first use simulated data to show that MLMs can outperform three standard methods that researchers use to identify environmental drivers of the species composition of communities, redundancy analysis (RDA), canonical correspondence analysis (CCA), and nonmetric multidimensional scaling (NMDS). In particular, MLMs can separate the effects of collinearity among environmental drivers and factor out the effect of changes in overall species abundances or occurrences that do not involve changes in composition. We then apply MLMs to presence/absence data for 14 species of understory herbs and topographic, biotic, and edaphic variables measured in 54 forested plots in the Southern Appalachian Mountains. In addition to providing information about community composition, MLMs simultaneously identify the responses of individual species to the environmental variables. Thus, MLMs not only have potentially superior statistical properties in analyses of community composition compared to standard methods, but they simultaneously provide detailed information about species-specific responses underlying the changes in community composition.

Jaffe, R., McKnight, D., Maie, N., Cory, R., McDowell, W., Campbell, J. 2008. Spatial and temporal variations in DOM composition in ecosystems: The importance of long-term monitoring of optical properties. Journal of Geophysical Research, 113(G4):G04032

Abstract
Source, transformation, and preservation mechanisms of dissolved organic matter (DOM) remain elemental questions in contemporary marine and aquatic sciences and represent a missing link in models of global elemental cycles. Although the chemical character of DOM is central to its fate in the global carbon cycle, DOM characterizations in long-term ecological research programs are rarely performed. We analyzed the variability in the quality of 134 DOM samples collected from 12 Long Term Ecological Research stations by quantification of organic carbon and nitrogen concentration in addition to analysis of UV-visible absorbance and fluorescence spectra. The fluorescence spectra were further characterized by parallel factor analysis. There was a large range in both concentration and quality of the DOM, with the dissolved organic carbon (DOC) concentration ranging from less than 1 mgC/L to over 30 mgC/L. The ranges of specific UV absorbance and fluorescence parameters suggested significant variations in DOM composition within a specific study area, on both spatial and temporal scales. There was no correlation between DOC concentration and any DOM quality parameter, illustrating that comparing across biomes, large variations in DOM quality are not necessarily associated with corresponding large ranges in DOC concentrations. The data presented here emphasize that optical properties of DOM can be highly variable and controlled by different physical (e.g., hydrology), chemical (e.g., photoreactivity/redox conditions), and biological (e.g., primary productivity) processes, and as such can have important ecological consequences. This study demonstrates that relatively simple DOM absorbance and/or fluorescence measurements can be incorporated into long-term ecological research and monitoring programs, resulting in advanced understanding of organic matter dynamics in aquatic ecosystems.

Jakeman, A.J., and G.M. Hornberger. 1993. How much complexity is warranted in a rainfall-runoff model? Water Resources Research. 29(8): 2637-2649.

Abstract
Development of mathematical models relating the precipitation incident upon a catchment to the streamflow emanating from the catchment has been a major focus of surface water hydrology for decades. Generally, values for parameters in such models must be selected so that runoff calculated from the model (matchesá recorded runoff from some historical period. Despite the fact that the physics governing the path of a drop of water through a catchment to the stream involves complex relationships, evidence indicates that the information content in a rainfall-runoff record is sufficient to support models of only very limited complexity. This begs the question of what limits the observed data place on the allowable complexity of rainfall-runoff models. Time series techniques are applied for estimating transfer functions to determine how many parameters are appropriate to describe the relationship between precipitation and streamflow in the case where data on only precipitation, air temperature and streamflow are available. Statistics from an (information matrixá provide the clues necessary for determining allowable model complexity. Time series models are developed for seven catchments with widely varying physical characteristics in different temperate climatic regimes to demonstrate the method. It is found that after modulating the measured rainfall using a nonlinear loss function, the rainfall-runoff response of all catchments is well represented using a linear model. Also, for all catchments a two-component linear model with four parameters is the model of choice. The Two compontes can be interpreted as defining a (quick flowá and (slow flowá response of the given catchment. The method therefore provides a statistically rigorous way to separate hydrographs and parameterize their response behavior. The ability to construct reliable transfer function models for describing the rainfall-runoff process offers a new approach to investigate empirically the controls of physical catchment descriptors, land use change, climate change, etc., on the dynamic response of catchments through the extensive analysis of historical data sets.

James S. Clark, Alan E. Gelfand, Christopher W. Woodall, and Kai Zhu 2014. More than the sum of the parts: forest climate response from joint species distribution models. Ecological Applications 24:990 - 999. http://dx.doi.org/10.1890/13-1015.1

Abstract
The perceived threat of climate change is often evaluated from species distribution models that are fitted to many species independently and then added together. This approach ignores the fact that species are jointly distributed and limit one another. Species respond to the same underlying climatic variables, and the abundance of any one species can be constrained by competition; a large increase in one is inevitably linked to declines of others. Omitting this basic relationship explains why responses modeled independently do not agree with the species richness or basal areas of actual forests. We introduce a joint species distribution modeling approach (JSDM), which is unique in three ways, and apply it to forests of eastern North America. First, it accommodates the joint distribution of species. Second, this joint distribution includes both abundance and presence– absence data. We solve the common issue of large numbers of zeros in abundance data by accommodating zeros in both stem counts and basal area data, i.e., a new approach to zero inflation. Finally, inverse prediction can be applied to the joint distribution of predictions to integrate the role of climate risks across all species and identify geographic areas where communities will change most (in terms of changes in abundance) with climate change. Application to forests in the eastern United States shows that climate can have greatest impact in the Northeast, due to temperature, and in the Upper Midwest, due to temperature and precipitation. Thus, these are the regions experiencing the fastest warming and are also identified as most responsive at this scale.

James S. Clark. 2009. Beyond Neutral Science. Trends in Ecology and Evolution, 24 (1): 8-15

Abstract
Biodiversity science is unusual in that an emerging paradigm is not based on a specific process, but rather depends largely on stochastic elements, perceived as neutral forces. Here I suggest that these forces, which have been justified, in part, by the concepts of symmetry and equalizing mechanisms, have application to the understanding of stochastic models but do not constitute forces that operate in nature. Another process now regularly classified as a neutral force, limited dispersal, represents a fundamental demographic process that is not neutral with respect to species differences, but rather differs among species in important ways. Finally, I suggest that the dramatic shift in ecological research to focus on neutrality could have a cost in terms of scientific understanding and relevance to real biodiversity threats.

Jensen, C. K., et al. (2014). Scales and arrangements of large wood in first- through fifth-order streams of the Blue Ridge Mountains. Physical Geography 35(6): 532-560.

Abstract
Large wood frequency and volume were examined as a function of landscape characteristics at different spatial and temporal scales in 50 reaches of the Upper Little Tennessee River basin with drainage areas ranging from 0.3 to 30.1 km2. Riparian forest cover was described laterally at the reach scale and longitudinally 1 km upstream in all tributaries. Riparian cover was analyzed with geomorphic and additional landscape variables to isolate factors that most influence wood in streams. Forested area immediately surrounding the reach was the strongest predictor of wood frequency and volume, although upstream riparian cover can explain additional variation in wood distributions. An optimal forested buffer width around the stream for large wood was not evident. The relationship between the riparian forest and wood weakens in bigger channels, as fluvial transport of pieces increases. Resurveys demonstrate that large wood is most dynamic in wide, forested reaches and changes function during floods to store sediment and organic matter.

John S. Kominoski, Amy D. Rosemond, Jonathan P. Benstead, Vladislav Gulis, John C. Maerz, and David W. P. Manning 2015. Low-to-moderate nitrogen and phosphorus concentrations accelerate microbially driven litter breakdown rates. Ecological Applications 25:856-865. http://dx.doi.org/10.1890/14-1113.1

Abstract
Particulate organic matter (POM) processing is an important driver of aquatic ecosystem productivity that is sensitive to nutrient enrichment and drives ecosystem carbon (C) loss. Although studies of single concentrations of nitrogen (N) or phosphorus (P) have shown effects at relatively low concentrations, responses of litter breakdown rates along gradients of low-to-moderate N and P concentrations are needed to establish likely interdependent effects of dual N and P enrichment on baseline activity in stream ecosystems. We established 25 combinations of dissolved inorganic N (DIN; 55–545 lg/L) and soluble reactive P (SRP; 4–86 lg/L) concentrations with corresponding N:P molar ratios of 2–127 in experimental stream channels. We excluded macroinvertebrates, focusing on microbially driven breakdown of maple (Acer rubrum L.) and rhododendron (Rhododendron maximum L.) leaf litter. Breakdown rates, k, per day (d1) and per degree-day (dd1), increased by up to 63for maple and 123for rhododendron over our N and P enrichment gradient compared to rates at low ambient N and P concentrations. The best models of k (d1 and dd1) included litter species identity and N and P concentrations; there was evidence for both additive and interactive effects of N and P. Models explaining variation in k dd1 were supported by N and P for both maple and rhododendron (R2 adj ¼0.67 and 0.33, respectively). Residuals in the relationship between k dd1 and N concentration were la