Recent History of Large-Scale Ecosystem Disturbances in North America Derived from the AVHRR Satellite Record
Ecosystems (2005) 8: 808-824 DOI: 10.1007/~10021-005-0041-6 Recent History of Large-Scale Ecosystem Disturbances in North America Derived from the AVHRR Satellite Record Christopher potter,'" Pang-Ning d an,' Vipin ~umar,'Chris ~ucharik,~ Steven ~looster; Vanessa ~enovese,~Warren ohe en,^ and Sean ~eale~~ 'NASA Ames Research Center, Moffett Field, California 94035, USA;2~niversity of Minnesota, Minneapolis, Minnesota 55415, USA; 3~niversityof Wisconsin, Madison, Wisconsin 53706, USA; *~aliforniaState University Monterey Bay, Seaside 93955, California, USA; USDA Forest Service, Corvallis, Oregon 97331, USA Ecosystem structure and function are strongly af- over i9 years, areas potentially influenced by ma- fected by disturbance events, many of which in jor ecosystem disturbances (one FPAR-LO event North America are associated with seasonal tem- over the period 1982-2000) total to more than perature extremes, wildfires, and tropical storms. 766,000 km2.The periods of highest detection fre- This study was conducted to evaluate patterns in a quency were 1987-1989, 1995-1 997, and 1999. 19-year record of global satellite observations of Sub-continental regions of the Pacific Northwest, vegetation phenology from the advanced very high Alaska, and Central Canada had the highest pro- resolution radiometer (AVHRR) as a means to portion (>90%) of FPAR-LO pixels detected in characterize major ecosystem disturbance events forests, tundra shrublands, and wetland areas. The and regimes. The fraction absorbed of photosyn- Great Lakes region showed the highest proportion thetically active radiation (FPAR) by vegetation (39%) of FPAR-LO pixels detected in cropland canopies worldwide has been computed at a areas, whereas the western United States showed monthly time interval from 1982 to 2000 and the highest proportion f 16% ) of FPAR-LO pixels gridded at a spatial resolution of 8-krn globally.
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