Spatial and Temporal Drivers of Fire Dynamics in the Amazon/Tocantins Basin

This study examines factors and processes explaining the current spatial and temporal distribution of fires in the Amazon/Tocantins basin. It combines mid-1990's observations of agricultural land-use and fires derived from the GOES-8 satellite with natural burned areas simulated using climatic and fuel load limitations. The spatial distributions of observed fires in 1995 and 1997 are generally similar, 1995 having significantly more fires (+10%). In several subregions, we find a significant correlation between spatial distributions of observed fires and land-use. Nevertheless, when considering the entire basin this relationship is not as pronounced due to land-use data set biases, as in Amazonas, or to inadequate spatial and temporal resolution needed to detect all fires, as in Tocantins and along the Andes. When comparing the spatial distributions of fires in 1995 to the different land-use types maps, planted pasture shows the best agreement with fire occurrence; cropland is often not a significant predictor, and natural pasture has an intermediate behavior. The main features of the 1997 minus 1995 differences of fire distribution can be explained by climatic anomalies. The strong 1997 El Niño event has a significant impact on the numbers and patterns of fire, especially in Bolivia and around Manaus where the associated precipitation changes are large. The 1997 minus 1995 differences in fire dynamics in regions with small changes in climate are probably the result of some anthropogenic factors. Interannual differences in climate factors, coupled with maps of land use, provide a strong basis for understanding and potentially predicting fire dynamics in this rapidly changing region.