Habitat degradation and loss

Numbers of threatened vertebrates: Africa

Note: critically endangered (extremely high risk of extinction in immediate future); endangered (very high risk of extinction in near future); vulnerable (high risk of extinction in medium-term future) The data include all globally threatened vertebrate species with country records in the UNEP-WCMC database (UNEPWCMC 2001a). Marine species recorded by ocean area are not included

Loss and degradation of habitat have been widespread over the past three decades. FAO's Global Forest Resources Assessment (FAO 2000) estimated the rate of deforestation in Africa during the period 1990-2000 as 0.78 per cent of total forest area a year, representing a yearly loss of some 5.2 million ha. The cause is primarily clearance for agriculture but extraction of timber and fuelwood, fire and overgrazing have also been important factors. Deliberate burning of grasslands is widely practised in many African countries, with 25-50 per cent of land cover in the arid Sudan zone and 60-80 per cent in the humid Guinea zone burned annually (Menaut and others 1991).

Impacts of habitat loss and degradation on biodiversity are difficult to evaluate. However, dramatic contractions in the range of many species have been recorded. For example, in Africa as a whole, elephants declined from about 1 300 000 to 500 000 during the 1980s. Declines were most pronounced in areas characterized by poaching, civil war, high rates of land use change and increases in human population densities (Happold 1995). Central Africa had lost about half of its wildlife habitats by 1986 (McNeely and others 1990). Draining of wetlands for agricultural and urban development, degradation through overgrazing and collection of fuelwood, and pollution through effluent discharge have caused the loss of up to 50 per cent of wetlands in Southern Africa (DEAT 1999) and Western Africa (Armah and Nyarko 1998, Oteng- Yeboah 1998), while some 80 per cent of the Upper Guinea forest has now been cleared (Conservation International 1999).

During 1980-95, the number of recorded extinct plants in Southern Africa increased from 39 to 58, and the number of threatened plants more than doubled (Hilton-Taylor 1996). Recent estimates indicate that more than 700 vertebrate species (see bar chart), around 1 000 species of trees (Hilton-Taylor 2000) and several hundred other plant species (IUCN 1997) are threatened with extinction.