Vulnerability to desertification in Africa is assessed using the information on soils, climate, and the previously evaluated land resource stresses. Desertification is, “land degradation in arid, semi-arid, and dry sub-humid areas resulting from various factors, including climatic variations and human activities”. Excluded in the definition are areas that have a hyper-arid or a humid climate. The GIS Desertification Vulnerability map was coupled to an interpolated population density map to obtain estimates of the number of persons affected by desertification. Desertification processes affect about 46% of Africa. The significance of this large area becomes evident when one considers that about 43% of the continent is characterized as extreme deserts (the desert margins represent the areas with very high vulnerability). Only about 11% of the land mass is humid and by definition is excluded from desertification processes. There are about 2.5 million km2 of land under low risk, 3.6 million km2 under moderate risk, 4.6 million km2 under high risk, and 2.9 million km2 under very high risk. The region that has the highest propensity is located along the desert margins and occupies about 5% of the land mass. It is estimated that about 22 million people (2.9% of the total population) live in this area. The low, moderate, and high vulnerability classes occupy 14, 16, and 11% respectively and together impact about 485 million people.
Agro-Science Vol.2(2) 2001: 1-10