The Amazon and other tropical regions have recently witnessed large-scale environmental changes due to road construction. However, previous research on the Amazon has yet to systematically document the link between the socio-spatial processes of road construction and the geometric signature of road networks on landscapes and ecosystems. On the one hand, the ecology literature approaches the issue of roads as a purely spatial phenomenon, and emphasizes the ensuing environmental impacts of habitat fragmentation without attending to the social processes driving road construction in the first place. On the other hand, social science research has only addressed the aggregate impact of road construction on deforestation, a rather blunt measure given the important ecological implications of various spatial geometries of forest fragmentation. As a result, a gap remains between the knowledge bases of ecological and social scientists concerned with roads and environmental change. What is needed is an understanding of the socio-spatial processes driving road extensions and how they are linked to the spatial architecture of the road networks that result.

We present a theoretical framework for understanding the socio-spatial processes of road extensions and how the spatial logic of extensions leads to road networks with variable spatial architectures. The framework draws on insights from microeconomic theory, work on tenure institutions and property rights, and political ecology to understand the process of road extensions by loggers, landholders, and coalitions of interest groups who seek to amplify road networks in the Amazon. Of particular concern is the social process by which road extensions occur, involving the driving forces and motivating objectives, the mobilization of capital, and the logic of spatial decisions for the pathways of new road sections. Out of this framework we derive a set of hypotheses concerning differences in the socio-spatial process of road extensions and the resulting spatial architecture of the road network on the basis of the agents involved. Among other things, we expect loggers and landholders to extend roads -- as they respond to different driving forces -- to fulfill different objectives and with different forms of capital, and that the resulting road networks will have distinct spatial architectures and different impacts on forest fragmentation.

To study the processes and results of road extensions in the Amazon, we will focus on the community of Uruará, situated on the Transamazon highway in the Brazilian state of Pará. While the Brazilian government opened the Transamazon in the 1970s, in-migration created local interest groups who have extended settlement roads leading off the highway, thereby fragmenting the forest. The research involves interviews with loggers, landholders and other participants in road extension efforts, and focuses on the socio-spatial processes leading to construction of individual road sections, with particular emphasis on the spatial decisions and resulting spatial architecture. The co-PIs have prior experience in the area, including preliminary interviews about extensions of some local roads.

The field interviews will generate a sample of road extensions under different historical and economic circumstances along the Transamazon. We will use these data in inferential tests on the derived hypotheses. We will also use them, together with digital map data covering the study area, to link road extension processes to the spatial architecture of resulting road networks. This will enable us to address gaps in the ecological and social science literatures regarding roads and ecological change by linking the specific characteristics of socio-spatial processes of road extensions to their spatial signature and forest fragmentation.