Human populations in the Amazon have grown from about 2.5 million in the 1960's to more than 20 million today. The dramatic influx of settlers has been encouraged by government activities designed to accelerate economic development in the region and to attract private capital.
The Amazon basin sustains nearly 60% of the world's remaining tropical rainforest and plays a vital role in maintaining biodiversity, regional hydrology and climate and terrestrial carbon storage. It also has the world's highest absolute rate of deforestation. In Brazilian Amazonia, which represents about 70% of the basin, deforestation rates since 1995 have averaged the equivalent of seven football fields per minute (nearly 2 million ha per year).
In this analysis of forest cover data from 1999 National Oceanic and Atmospheric Administration imagery, soil fertility and waterlogging had little value as predictors of deforestation. Soil depth was only marginally significant. Distance to the nearest river, or the nearest road, were far less significant than distance to the nearest highway.
According to Laurance, "our findings predict that current policy initiatives designed to increase immigration and dramatically expand highway and infrastructure networks in the Brazilian Amazon will have important impacts on deforestation activity. Deforestation will be greatest in relatively seasonal, south-easterly areas of the basin, which are most accessible to major population centers and where large-scale cattle ranching an
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Contact: William F. Laurance
laurancew@tivoli.si.edu
Smithsonian Tropical Research Institute
5-Jul-2002