HR: 14:55h
AN: B53A-06    [Abstracts]
TI: Carbon Dynamics in Mid-Atlantic Temperate Forests: Responses to Changes in Atmospheric Chemistry and Climate
AU: * Pan, Y
EM: ypan@fs.fed.us
AF: USDA Forest Service, 11 Campus Blvd, Newtown Square, PA 19073 United States
AU: Birdsey, R
EM: rbirdsey@fs.fed.us
AF: USDA Forest Service, 11 Campus Blvd, Newtown Square, PA 19073 United States
AU: Hom, J
EM: jhom@fs.fed.us
AF: USDA Forest Service, 11 Campus Blvd, Newtown Square, PA 19073 United States
AU: McCullough, K
EM: kmccullough@fs.fed.us
AF: USDA Forest Service, 11 Campus Blvd, Newtown Square, PA 19073 United States
AB: This study examines how multiple stresses -- changing climate and atmospheric composition of CO₂, O₃ and N deposition -- affect productivity, carbon storage, and sequestration of Mid-Atlantic temperate forests. We use a process-based ecosystem model, PnET-CN, that has a strong foundation of ecosystem process knowledge from experimental studies. Our results suggest that the chronic changes in atmospheric chemistry in the past decades markedly affect carbon dynamics and sequestration in Mid-Atlantic temperate forests. At the regional scale, net primary production has increased by 28% in response to the three major atmospheric chemical changes. In the last 70 years, carbon sequestered in live forest biomass increased by 20%, while the carbon increase in soil organic matter was 18%. More fundamentally, changes in atmospheric chemistry components exert impacts on ecophysiological processes and ecosystem functioning. The modeling results suggest that N deposition is a stronger force than elevated CO₂ for increasing primary production. Ozone pollution offsets about 22% of enhanced biochemical capacity for photosynthesis. Changes in interannual variability of climate during past decades add complexity to forest responses to changing atmospheric chemistry. As annual NPP increases along with increased precipitation and temperature in the region, annual NEP appears to decline, likely caused by accelerated decomposition processes. Because of the complexity of interactions among multiple stresses, and the limitations of the experimental approach, the process-based mechanistic model is shown as a powerful tool in this study to predict ecosystem-level responses and attribute causation to various climatic drivers and different environmental factors.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0400 BIOGEOSCIENCES
DE: 3309 Climatology (1616, 1620, 3305, 4215, 8408)
DE: 3322 Land/atmosphere interactions (1218, 1631, 1843)
DE: 4805 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912)
SC: Biogeosciences [B]
MN: Fall Meeting 2005