Forest and Pasture Carbon Pools and Soil Respiration in the Southern Appalachian Mountains

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 aboveand belowground C pools and soil respiration flux at four forested and four pasture sites in the southern Appalachian Mountains. Aboveand 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. FOR. SCI. 51(4):372-383.