| Although a large literature now exists on the drivers of tropical deforestation, less is known about its spatial manifestation. This is a critical shortcoming in our knowledge base, since the spatial pattern of land cover change, and forest fragmentation in particular, strongly affect biodiversity. The purpose of this dissertation is to consider emergent patterns of road networks, the initial proximate cause of fragmentation in tropical forest frontiers. Specifically, I address the road building processes of loggers, who are very active in the Amazonian landscape. To this end, I develop an explanation of road expansions combining a theoretical model of economic behavior with geographic information system (GIS) software in order to mimic the spatial decisions of road builders. I simulate three types of road extensions commonly found in the Amazon basin. The first two types are roads that spur off the initial infrastructure constructed by the government in official settlement areas such as the Transamazon and are related to the fishbone pattern of fragmentation. The third type of roads are the skid trail networks, built to access individual trees. I developed several raster based GIS algorithms to model each type of road. Although my simulation results are only partially successful, they call the attention to the role of multiple agents in the landscape, the importance of legal and institutional constraints on economic behavior, and the power of GIS as a research tool. |
