Turner, David P.; Koerper, Greg J.; Harmon, Mark E.; Lee, Jeffrey J. 1995. A carbon budget for forests of the conterminous United States. Ecological Applications. 5(2): 421-436.
The potential need for national-level comparisons of greenhouse gas emis-sions, and the desirability of understanding terrestrial sources and sinks of carbon, hasprompted interest in quantifying national forest carbon budgets. In this study, we link aforest inventory database, a set of stand-level carbon budgets, and information on harvestlevels in order to estimate the current pools and flux of carbon in forests of the conterminousUnited States. The forest inventory specifies the region, forest type, age class, productivityclass, management intensity, and ownership of all timberland. The stand-level carbon bud-gets are based on growth and yield tables, in combination with additional information oncarbon in soils, the forest floor, woody debris, and the understory. Total carbon in forestsof the conterminous U.S. is estimated at 36.7 Pg, with half of that in the soil compartment.Tree carbon represents 33% of the total, followed by woody debris (10%), the forest floor(6%), and the understory (1%). The carbon uptake associated with net annual growth is331 Tg, however, much of that is balanced by harvest-related mortality (266 Tg) anddecomposition of woody debris. The forest land base at the national level is accumulating79 Tg/yr, with the largest carbon gain in the Northeast region. The similarity in the mag-nitude of the biologically driven flux and the harvest-related flux indicates the importanceof employing an age-class-based inventory, and of including effects associated with forestharvest and harvest residue, when modeling national carbon budgets in the temperate zone.
Key words: age-class distribution; carbon pools and flux; carbon sources and sinks; forest carbonbudget; forest inventory; net ecosystem productivity; regional carbon storage; soil carbon; tree harvest;United States; woody debris.