Agricultural land-use change in Brazilian Amazonia between 1980 and 1995: Evidence from integrated satellite and census data

摘要

As cropland and pasture have replaced forest and cerrado in Brazilian Amazonia, concern has mounted over the effects of changing the biogeochemical and hydrological properties of one of the world's great storehouses of biomass and biodiversity. Although much recent effort has focused on the location, effects, and causes of deforestation and cerrado conversion, much less is known about the basin-wide spatial distribution and density of the land use following conversion for crops or pasture. In this paper, we use census and satellite records to develop maps of the distribution and abundance of major agricultural land uses across 4.5×10{sup}8 ha of Brazilian Amazonia in 1980 and 1995. Results indicate an overall expansion of 7.0× 10{sup}6 ha in total agricultural area in Brazilian Amazonia between 1980 and 1995. The net change during this period is estimated for three different land-use types: croplands (an increase of 0.8×10{sup}6 ha), natural pastures (a decrease of 8.4×10{sup}6 ha), and planted pastures (an increase of 14.7×10{sup}6 ha). These estimates, the first spatially explicit quantifications of agricultural land-use activities in 1980 and 1995 across Brazilian Amazonia, are shown to be consistent with the results of applying a land use change and secondary regrowth model to published deforestation rates for the period. The resulting time slices, presented for each land-use category at 5-min ( 9 km) spatial resolution, allow for the quantification of land-use changes in this region for biogeochemical, demographic and economic models. Several foci of agricultural change existed within Brazilian Amazonia during this period: in the state of Para, cropland was lost and planted pasture increased markedly; in Mato Grosso, both cropland and planted pasture increased; in Rondonia, planted pasture replacing forest was the primary route to agricultural expansion.