Humanizing Savanna Biogeography: Linking Human Practices with Ecological Patterns in a Frequently Burned Savanna of Southern Mali

Abstract

The savanna biome is defined by the codominance of grasses and trees, the precise ratio of which is a function of numerous variables, both natural and anthropogenic. Fire is a critical determinant of the tree-to-grass ratio because it can suppress tree establishment and growth. Despite the fact that nearly all fires have human causes, most savanna fire ecology models are based solely on ecological variables and fail to integrate human land and fire use patterns. To understand how human burning practices, land cover patterns, and fire regimes are linked I combined the results of an image-based burn scar analysis and land cover maps generated from a Landsat database covering thirty years with interview and survey results. I documented the spatially explicit fire regime for an area of Sudan savanna in southern Mali and linked it to human practices and land cover patterns. The study concludes that burning creates a seasonal mosaic in which some patches regularly burn early and others late, whereas some areas rarely if ever burn. Ecologists attribute mosaic fire regimes to natural factors such as plant succession, but this research demonstrates that the regime is a function of the combined effects of edaphic conditions, vegetation patterns, land use, and widespread burning practices. The anthropogenic burning regime documented here differs from the one based on ecological theory in that its spatiotemporal pattern is relatively consistent from year to year. The findings demonstrate the need to “humanize” savanna models by breaking nature–society dichotomies and synthesizing natural and social science explanations.