Patterns and causes of deforestation in the Colombian Amazon

Ecosystem information on the Colombian Amazonia is poor in comparison with that on the Brazilian Amazon. We examined patterns of ecosystem diversity, deforestation and fragmentation and provided an estimate on their possible causes through a temporal and spatial analysis of biotic and abiotic data using remote sensing and geographical information systems in six pilot areas covering a total of 4,200,000 ha. Ecological, demographic and socio-economic data were analysed to establish the local conditions. We used a landscape ecology approach to calculate indicators of ecosystem diversity, cover and forest fragmentation such as number of patches, mean patch size, mean shape index and mean nearest neighbour distance. Patterns of deforestation did not run parallel to access roads; instead the typical pattern of unplanned colonization follows the only transportation network existing in many areas in the Colombian Amazonia: rivers. In addition, we have used indicators of human influence such as demographic pressure, quality of life and economic activity indicators. Results show that the extent and rate of change varies between areas depending on population density. Annual deforestation rates were 3.73 and 0.97% in the high population density growth areas of Alto Putumayo and Macarena respectively, and 0.31, 0.23, and 0.01% in the relatively unpopulated areas of indigenous population. These changes are related to land use history as well as to environmental and historical socio-economic factors such as oil extraction, deforestation, cattle ranching or illegal cropping. The current situation in the region suggests that tropical deforestation rates in the Colombian Amazon are substantially higher than those found in previous studies in the rest of the Amazon.