Land-atmosphere feedbacks amplifying climate change in the Sahel. Click on image for a zoom.
From Dryland Systems in Ecosystems and Human Well-Being: Current State and Trends, part of the Millennium Assessment.
Service of Climate Regulation in Drylands. The central grey box --the components of biodiversity involved in service provision-- maintenance of soil moisture (bottom left) and modulation of rainfall (top). IN bold -- the major alternative/complementary function involved in the effect of live vegetation cover on rainfall: successive multiplication of signs along each trajectory generates an increase in rainfall (+) when service is ameliorated and a decrease in rainfall (-) when land is degraded. Land degradation (grey circle) degrade the service through affecting surface temperature; when surface temperatures increase along the albedo trajectory, it decreases along the evaporation trajectory; this trend is reversed when land is not degraded.
Much more information on desertification in Africa.