Sahara Desert in West Africa as forests in the region were gradually cleared (Aubreville, 1949). Literally, desertification means the making of a desert, but although the word has been in use for more than 50 years, a universally agreed definition of the term has only recently been arrived at. A survey of the literature on the subject has revealed more than a hundred different definitions (Glantz and Orlovsky, 1983) and most of these suggest that the extent of deserts is increasing, usually into desert-marginal lands. The idea of a loss of an area’s resource potential, through the depletion of soil cover, vegetation cover or certain useful plant species, for example, is included in many definitions. Some suggest that such losses are irreversible over the timescale of a human lifetime.