Defining desertification: A review

The concept of desertification was introduced in the late forties to designate a number of ecological degradation processes in tropical Africa, in particular the progressive transformation of tropical forests in savannahs or even drier ecosystems. Since then, the word has received a number of other meanings, some of them contradictory, most of them ambiguous.This paper reviews the historical developments that lead to the introduction of the concept of desertification, summarizes some of the reasons why this issue is so controversial, and suggests specific elements that should be incorporated in the definition of the concept. The point is made that each user of the concept should probably design a definition for his or her own use, depending on the goals, among other things.The National Center for Atmospheric Research is operated by the University Corporation for Atmospheric Research and sponsored by the National Science Foundation.