CWT-LTER Data Set Summary

Accession: 1035 CWT Research Theme: Disturbance and Land Use
Contributor: Barton D. Clinton
Title: Gap PAR (Photosynthetic Active Radiation) at the Coweeta Hydrologic Laboratory from 1993 to 1997
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 (degrees C), photosynthetically active radiation (PAR; mmol m-2s-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.
Key Words: biweekly, canopy gaps, Coweeta Hydrologic Laboratory, Coweeta LTER, CWT, forest structure and function, light, LTER, microclimate, North Carolina, Otto, PAR, photosynthetic active radiation, plant ecology, soil moisture, temperature, understory, USDA Forest Service
LTER Core Area: Disturbance Patterns
CWT Themes: Disturbance and Land Use, Climate & Climate Change
Study Type: Coweeta Terrestrial Study
Study Period: 01-Apr-1993 to 30-Apr-1997
Site References:
WS18 -- Watershed 18, North Carolina, USA
WS27 -- Watershed 27, North Carolina, USA
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Data Table: 1035 (Main data table for data set 1035, 3180)

Access: Public (released 22-Jun-2003)

Metadata: Text (ESA FLED), Basic EML, Complete EML

Data Formats: Spreadsheet CSV Text Format, EML-described Text Format, Tab-delimited Text Report with Statistical Summary, GCE Data Toolbox Format, Standard MATLAB Variables Format

Column List:

Column Name Units Type Description (hide)
1 Site none integer Site ID where measure was taken.
2 Year YYYY integer Year when measure was made
3 Julian_day none integer Julian day of measure
4 Plot none integer Plot ID within Site.
5 Location none integer Location within plot
6 PAR mmol/m^2/s floating-point Photosynthetic Active Radiation; millimoles of photons per meter squared per second (millimol m-2 s-1)
7 PAR_full_sun mmol/m^2/s floating-point PAR reading taken in the open away from tree canopies ; millimoles of photons per meter squared per second (millimol m-2 s-1)