Tuesday, August 3, 2010
Exhibit Hall A, David L Lawrence Convention Center
Daolan Zheng1, Linda S. Heath2, Mark J. Ducey1 and James E. Smith3, (1)Natural Resources and the Environment, The University of New Hampshire, Durham, NH, (2)USDA Forest Service, Northern Research Station, Durham, NH, (3)US Forest Service, Northern Research Station, Durham, NH
Background/Question/Methods Both climate and human disturbances affect forest carbon dynamics but human-introduced disturbances may have greater impact than climate does over shorter time scales (e.g., years, decades). Thus, an integrated analysis including all major components of human-introduced disturbances on forest carbon dynamics are necessary. This study illustrates how forest growth, land-use/cover change (LUCC), harvesting and use of harvested wood products, and fires affect nonsoil forest carbon dynamics in the 31 states of eastern U.S. based on 30-m national Retrofit Change Product (1992 to 2001) derived from remote sensing observations and ground inventory data from various sources. We use gross forest land change statuses (i.e., afforestation, deforestation, forestland remaining forestland), rather than net land-cover transition data, to improve carbon estimation because their effects on carbon dynamics differ substantially: while afforestation causes a gradual carbon accumulation for many decades, deforestation causes a much more rapid loss in carbon stocks.
Results/Conclusions
The region as a whole experienced 4% (or 123000 km2) LUCC between 1992 and 2001, 33% higher than 3% for the nation on average (excluding Alaska and Hawaii). Within the 4% change, 77.9% (or 95800 km2) was forest related with a net change of regional forest area loss of 39000 km2. Regional forests sequestered 1577 Tg C during the 9-year period before explicitly considering harvest and fire disturbances. While harvest activities and deforestation rates were well correlated at the state level across the region; the former had much more impact on forest C dynamics (104% higher) than that resulting from deforestation, with a net C emission of 938 Tg for harvesting versus 455 Tg for deforestation. Wildfire showed little impact (10 Tg C) on regional carbon dynamics. After incorporating harvest and fire effects, the region sequestered 629 Tg C during the period, which is an average annual rate of 70 Tg C. Carbon dynamics within the region varied substantially at the state level ranging from a C sink of 97 Tg in PA to a C source of 54 Tg in GA during the 9-year period. Forest dynamics of growth, LUCC, and harvesting were much more dramatic in the southern region than those in the northern region between 1992 and 2001. Consequently, the northern forests functioned as a strong C sink at 71 Tg/yr while the southern forests turned to be a small C source at 1 Tg/yr.
