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Major Environmental Concerns  More

[ Land | Forest | Biodiversity | Water | Marine & Coastal Environments | Urban & Industrial Environments ]


Underlying Causes More

[ Social | Economic | Institutional | Environmental ]


This continent contains the world's largest expanse of drylands, covering roughly 2 billion hectares of the continent or 65 per cent of Africa 's total land area (UNEP, 1991a). One third of this area is hyper-arid deserts, while the remaining two thirds consists of arid, semi-arid, and dry sub-humid areas-home to about 400 million Africans, two thirds of the continent's total. Recurrent droughts are a permanent fact of life throughout the drylands of Africa . Severe droughts have seriously affected both agriculture and wildlife and caused deaths and severe malnutrition. With each drought cycle, desertification increases. Currently, 36 countries in Africa are affected by drought and some degree of desertification (UNEP, 1994). The risk of drought is high in the Sudano-Sahelian belt and in southern Africa .

Land degradation, which includes degradation of vegetation cover and soil degradation, has been identified as a major problem in Africa . The extent of the problem continent-wide is difficult to determine precisely due to lack of data, particularly on vegetation cover degradation. The Global Assessment of Soil Degradation (UNEP/ISRIC, 1990; UNEP, 1991c) estimated that about a half-billion hectares in Africa are moderately to severely degraded, corresponding to one third of all cropland and permanent pasture on the continent. Some national reports, especially in northern Africa , indicate much higher percentages of degradation.

The main causes of the soil degradation are overgrazing, particularly in drylands; extensive clearing of vegetation for agriculture; deforestation; extensive cultivation of marginal lands; the use of inappropriate agricultural technology; poor management of arable lands; and droughts (UNECA, 1992; Thomas and Middleton, 1993; Ohlsson, 1995). (See also Figure 2.1 a, b, c, and d.) Other contributors, particularly in the southern African countries, are thought to include land shortages, usually due to the unequal distribution of land, and the modernization of agriculture that has led to marginalization of subsistence farming (Dahlberg, 1994). All these activities lead to depletion of soil fertility, water and wind erosion, and salinization (UNEP/ISRIC, 1990; Thomas and Middleton, 1993).

Land degradation is exacerbating the existing natural constraints on agricultural production, including poor soil quality, variable climatic conditions, and reliance on rainfed agriculture. About 90 per cent of African soils are deficient in phosphorus, a key nutrient in the production of biomass. These soils also have low content of organic matter, and low water infiltration and retention capacity due to surface crusting. Moreover, about half the cultivable land (or three quarters of land already cultivated) is under arid and semi-arid conditions, so potential for irrigation is limited (World Bank, 1995).

Agriculture is the fundamental economic activity in most African countries, averaging 20-30 per cent of gross domestic product (GDP) in sub-Saharan Africa, and 55 per cent of the total value of exports (excluding the oil-producing countries). Yet land degradation, coupled with rapid population growth, is increasing deficits in food production and food insecurity. Although a serious information gap exists regarding the productivity impacts of degradation, rough estimates indicate that, on average, land areas affected by degradation have lost about 20 per cent of their productivity during the last decade (World Bank, 1995).

United Nations Environment Programme
United Nations Environment Programme





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