Modeling the Spatial Transition Probabilities of Landscape Dynamics in an Amazonian Colonization Frontier

Many researchers concerned about the enormous ecological impact of deforestation in the Amazon have turned their attention to this rich biome, which is the largest tropical forest in the world. Indeed, the Amazon is among the highest priorities for biodiversity protection (Myers 1988). Research agencies have carried out several mapping projects aimed at assessing and monitoring the extent and rates of deforestation (e.g., Skole and Tucker 1993, INPE and FUNCATE 1996, INPE 1999). Their results show that not only has deforestation already widely and deeply affected the Amazon, but it even accelerated in the late 1990s (MCT 1998, INPE 1999). Still new threats are posed to this important ecological region as the Brazilian government launches its “Avança Brasil” (Advance Brazil) development plan for the Amazon, which involves over US$45 billion in investments for road paving, river channeling, and energy production (Carvalho et al. 2001a, Laurance et al. 2001). Despite high deforestation rates, large tracts of previously cultivated land are being abandoned, allowing a regeneration process that produces secondary forest. The Amazonian landscape that evolves comprises a mosaic of pasture patches—the most dominant land use in the Amazon—among fragments of impoverished forest remnants and myriad regrowth patches occupied by secondary vegetation in several stages of succession (Fearnside 1986, 1996, Uhl 1987, Uhl et al. 1988a, 1988b, Nepstad et al. 1991, Moran et al. 1994, Skole et al. 1994, Fearnside and Guimarães 1996, Steininger 1996, Kimes et al. 1998, Nelson et al. 2000). Thus, the study of Amazonian landscape dynamics requires an understanding of the processes that rule land-use conversion, agricultural land abandonment, and forest recovery. To gain that understanding, researchers need accurate measurements of changes; they must also attempt to determine the spatial trends of changes, and by that means evaluate the possible paths of the Amazon's evolution and its ecological implications.