Desertification and drylands development: what can be done?

By analysing the concept of desertification and the evolution of its definitions, five main themes were selected. The perception of the causes of desertification has shifted from blaming colonization to climate change and finally to the traditional land-use systems. In the 1960s in Africa, the trend was to attribute land degradation to sectorial development during colonization. During the 1970s, essentially because of UNEP efforts, middle-term climate changes and short-term droughts were considered as causes of desertification, while distinguishing meteorological, hydrological, edaphic and agricultural droughts. The consensus view of the last decades now is that desertification is primarily human induced: among them the effects of traditional indigenous land management and of imported exogenous land management can be distinguished. To separate climate-induced, short-term environmental changes from land degradation induced by human activities is impossible. What can be achieved in drylands? It is obviously erroneous to propose dry ecosystem development on the model of highly mechanized developed countries. Drylands development requires much more input, leading to accelerated waste production. It cannot follow the same scheme as in temperate or in wet-tropical ecosystems. They need higher investment and risk more irreversible land degradation. The drylands are financial sinks. Rehabilitation of the environment together with demographic control should have priority. Finally, preference should be given to small projects of irrigation rather than huge complex plans. © 1998 John Wiley & Sons, Ltd.