The term “desertification” was first used in the early twentieth century. Its use spread quickly throughout colonial Africa, rein forced by the powerful image of the encroaching desert. From the outset, the causes of desertification have been linked to climate aridification (“desiccation”) and environmental degra dation, particularly that related to vegetation cover (deforest ation, savannization, etc.) and soil (wind erosion, run-off, loss of fertility, etc.).