Ecosystem carbon stocks in Pinus palustris forests

Longleaf pine (Pinus palustris Mill.) restoration in the southeastern United States offers opportunities for carbon (C) sequestration. Ecosystem C stocks are not well understood in longleaf pine forests, which are typically of low density and maintained by prescribed fire. The objectives of this research were to develop allometric equations for aboveand below-ground biomass and quantify ecosystem C stocks in five longleaf pine forests ranging in age from 5 to 87 years and in basal area from 0.4 to 22.6m2·ha−1. Live aboveground C (woody plant + ground cover) and live root C (longleaf pine below stump + plot level coarse roots + plot level fine roots) ranged from 1.4 and 2.9 Mg C·ha−1, respectively, in the 5-year-old stand to 78.4 and 19.2 Mg C·ha−1, respectively, in the 87-year-old stand. Total ecosystem C (live plant + dead organic matter + mineral soil) values were 71.6, 110.1, 124.6, 141.4, and 185.4 Mg C·ha−1 in the 5-, 12-, 21-, 64-, and 87-year-old stands, respectively, and dominated by tree C and soil C. In the 5-year-old stand, ground cover C and residual taproot C were significant C stocks. This unique, in-depth assessment of aboveand below-groundC across a series of longleaf pine standswill improve estimates of C in longleaf pine ecosystems and contribute to development of general biomass models that account for variation in climate, site, and management history in an important but understudied ecosystem.