HR: 16:30h
AN: B12G-03    [PDF]
TI: Disturbance-Driven Ecosystem Productivity Estimates From the Integration of a Biogeochemistry Model and Landsat Remote Sensing
AU: * Masek, J G
EM: Jeffrey.G.Masek@nasa.gov
AF: Biospheric Sciences, NASA GSFC, Code 923 NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Collatz, G J
EM: jcollatz@biome2.gsfc.nasa.gov
AF: Biospheric Sciences, NASA GSFC, Code 923 NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AB: Accurately modeling carbon fluxes between the land biosphere and atmosphere requires knowing the age structure and disturbance regime of forests. Recent eddy flux experiments within forest chronosequences have supported the theory that net ecosystem productivity (NEP) increases during the first decades after a stand-clearing disturbance, and then drops toward equilibrium. While the magnitude of this trajectory depends on stand type, it is possible that changes in disturbance rates could help explain both decadal and year-to-year variability in atmospheric carbon dioxide concentrations. However, testing this hypothesis requires forest disturbance and recovery histories at regional to continental scales. We are exploring approaches to derive disturbance history from Landsat surface reflectance data, and integrate this information with the CASA biogeochemistry model to make geographically explicit predictions of NEP and its variability. Using a test area in Central Virginia, we have mapped the extent of forest harvest and regrowth since 1973. We have modified the CASA model to account for the effects of disturbance and recovery on NPP and carbon pools. Inventory data from the USDA Forest Service have been used to calibrate CASA to predict NEP as a function of age for planted pine and mixed pine-hardwood forest types. This presentation will describe interannual changes in NEP resulting from disturbance and recovery dynamics, and compare the magnitude of these changes to those expected from a model driven by climate variability alone. The possible extension of this approach to the continental scale in support of the North American Carbon Program will also be discussed.
DE: 0315 Biosphere/atmosphere interactions
DE: 0400 Biogeosciences
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting