ASSESSMENT OF GLOBAL FOREST CHANGE BETWEEN 1986 AND 1993 USING SATELLITE-DERIVED TERRESTRIAL NET PRIMARY PRODUCTIVITY

Although forest removal has been well documented at a global level, kn owledge of how major forest processes such as photosynthesis have been affected remains poor. Global forest change between 1986 and 1993 was assessed using the NOAA/AVHRR satellite data converted to terrestrial net primary productivity (NPP). Forest loss was a dominant feature in tropical regions, with the most severe destruction in Latin America f ollowed by southeast Asia and Africa. Loss of high-productivity forest s over wide areas was observed for countries such as Brazil and Bolivi a. Further analysis showed that approximately 12% (9 100 999 km(2)) an d 19% (2 600 000 km(2)) of the low-NPP regions (< 500 g m(-2) yr(-1), e.g., deserts, tundra) and the high-NPP regions (> 2000 g m(-2)yr(-1), e.g., tropical rain forests), respectively, were transformed to inter mediate-NPP regions (500-1500 g m(-2) yr(-1), e.g., savanna, grassland , or cultivated land), between 1986 and 1993. The extent of global for est degradation or fragmentation may be more severe than the deforesta tion itself Low-latitude ecosystems were more prone to decline in NPP than mid- and high-latitude ecosystems. The NPP method offers insight into global forest change in a timely, practical and consistent manner .