Thursday, August 6, 2009
Exhibit Hall NE & SE, Albuquerque Convention Center
William B. Whitaker1, Lisa J. Samuelson2, Tom A. Stokes2 and John S. Kush3, (1)Center for Longleaf Pine Ecosystems, Auburn University, Auburn, AL, (2)Center for Longleaf Pine Ecosystems, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL, (3)Longleaf Pine Stand Dynamics Laboratory, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL
Background/Question/Methods Global climate change and the accumulation of the greenhouse gas carbon dioxide (CO2) in the atmosphere can be mitigated by the proper management of soils and forests through carbon sequestration. Particularly, longleaf pine (Pinus palustris Mill.) forests, which historically dominated the upper and lower Coastal Plain in the southeastern United States, have the potential to sequester large quantities of carbon through long rotations and temperate climatic conditions. Soils compose the largest carbon sinks on earth and thus have potential to be the largest contributors of CO2 to total ecosystem respiration. More knowledge on the effects of stand and community structure on soil respiration rates is needed to understand how forest management influences carbon cycling. The objective of this study was to examine how forest structure influences the rate of soil respiration to better understand forest management effects on carbon pools. Soil respiration was examined over a 10 month period on the Escambia Experimental Forest near Brewton, AL in response to basal area, root biomass, woody debris in the soil, soil charcoal mass, litter depth, litter mass, downed woody debris, aboveground woody biomass, percent ground cover, and environmental conditions. Results/Conclusions
Basal areas ranged from 7 to 36 m2 ha-1 and percent ground cover, litter mass, litter depth, soil woody debris, and downed woody debris varied with basal area but soil temperature did not. Mean monthly soil respiration rates ranged from 1.4 µmol m-2 s-1 in February to 7.0 µmol m-2 s-1 in July. Soil respiration increased exponentially with soil temperature and temperature explained 96% of the variation in soil respiration. Litter mass, percent ground cover, litter depth, basal area, and soil moisture were weakly related to soil respiration (0.4 – 2.8 %). These results indicate that soil carbon efflux can be modeled using soil temperatures and that forest management practices that influence soil temperature rather than forest structure per se will influence soil carbon efflux.
