North American Disturbance Rates Assessed from LEDAPS Satellite Analysis
Jeffrey
G
Masek, NASA GSFC, Jeffrey.G.Masek@nasa.gov
(Presenting)
Forrest
Hall, NASA GSFC / UMBC, fghall@ltpmail.gsfc.nasa.gov
Chengquan
Huang, U. Maryland, Dept. Geography, cqhuang@umd.edu
Samuel
Goward, U. Maryland, Dept. Geography, sgoward@umd.edu
Robert
Wolfe, NASA GSFC, rwolfe@pop900.gsfc.nasa.gov
Warren
Cohen, US Forest Service, PNW Station, warren.cohen@oregonstate.edu
Stand clearing disturbances (harvest, fire) are thought to play a major role in controlling land-atmosphere fluxes of carbon. Under the auspices of the North American Carbon Program, the LEDAPS (Landsat Ecosystem Disturbance Adaptive Processing System) has been analyzing the Landsat satellite record to assess rates of forest disturbance across North America. Wall-to-wall Landsat coverage for the period 1975-2000 has been converted to surface reflectance and analyzed for decadal losses (disturbance) or gains (regrowth) in biomass using a spectral “disturbance index”. Preliminary (unvalidated) results for the 1990’s indicate high rates of harvest within the southeastern US, Eastern Canada, and the Pacific Northwest, with spatially averaged (~50x50 km) turnover periods as low as 25-40 years. Lower rates of disturbance are found in the Rockies and Northeastern US. Validation of these results is occurring via visual analysis of image subsets and comparison with FIA data. This poster will give an overview of the LEDAPS processing and validation efforts, present recent results, and discuss lessons learned for large area analyses using high-resolution satellite data.