Physical and social access to land: spatio-temporal patterns of agricultural expansion in Madagascar

The expansion of agriculture is posited as one of the main dynamics of land cover change globally, and the robust modeling of these processes is important for policy as well as academic concerns. Madagascar's farmers stand accused as the "proximate agents" of land conversion in one of the world's "hottest" biodiversity hotspots, and numerous studies have been conducted to describe and model the processes by which the country's forests are giving way to agriculture. This paper concerns a relatively small area on the island's eastern escarpment where considerable national and international attention has been paid to slow the expansion of agriculture into the remaining natural forests. The approach adopted here is to begin by examining the degree to which patterns of agricultural conversion can be attributed to a set of factors that have been identified as significant at broader scales in Madagascar and elsewhere, namely topography and prior human settlement and land use patterns. A regression model is constructed, and its predictions compared to the observed land conversion over a 43-year period. The study then examines in detail the spatial patterns highlighted by the failure of the model (the residuals of the regression), breaking the study area into smaller zones, or landscapes. The spatio-temporal trajectories of these zones are then contrasted, with particular attention to the institutional arrangements governing access to land resources. The study finds that while overall land change patterns in the region are largely explained by elevation and village proximity, more specific, sub-regional, trajectories reflect the signatures of institutions governing access to land.