Africa offers a wide spectrum of habitats and ecosystems. Biological diversity varies in complex ways, depending on local moisture regimes, topography, vegetation, and soil type. Countries such as Zaire, which has large areas of land in the humid tropics, and South Africa, Kenya, and Tanzania-with impressively variable landscapes-are famous for their high species diversity and impressive wildlife populations. Some island States in the Indian Ocean are rich in endemic species (UNEP, 1994).

Savannahs (consisting of savannah woodland, tree savannah, shrub savannah, and grass savannah) are the most extensive ecosystem in Africa and provide a home for the majority of humans, livestock, and wildlife. They are the richest grassland regions in the world, with a high incidence of indigenous plants and animals and the world's greatest concentration of large mammals, particularly in northern Tanzania (WCMC, 1992).

Several African mountains and highlands have unique and rich biodiversity, with a number of endemic animal and plant species. These areas include mountain ranges or chains such as the Atlas, Rwenzori, and Aberdare mountains; more uniform volcanic cones such as Mount Kenya, Mount Kilimanjaro, and Mount Cameroon; valleys and escarpments such as the Rift Valley and the Nile gorge; and highlands and plateaus such as those found in Ethiopia, Kenya, and southern Africa. Particularly in the tropical and subtropical regions of Africa, the sloping areas surrounding high altitudes are of great importance for development (UNEP, 1994).

Wetlands cover about 1 per cent of Africa's total surface area and are found in every country (WCMC, 1992). The largest include the Zaire swamps, the Sudd in the Upper Nile, the Lake Victoria and Chad basins, the Okavango Delta, and the floodplains and deltas of the Niger and Zambezi rivers. The diversity of flora and fauna of wetlands in Africa is immense and in many places unknown, with endemic and rare plant species and wildlife, including migratory bird species (UNEP, 1994). Many wetlands are under threat from conversion (drainage and filling), overuse, pollution from farm runoff and untreated urban and industrial effluents, and unplanned development. Also, the fact that freshwater fish are a primary source of protein and income in many local communities can threaten biodiversity. Furthermore, a substantial number of species in water masses are threatened with extinction from new species that were introduced in the absence of environmental impact assessments (WCMC, 1992), as happened in Lake Victoria (Roest, 1992).

The African coastal region is vast, and includes a variety of habitats. Diversity of fish species is high, with more than 4,000 species reported. Some of the most numerous and economically most important fish species are tuna, marlin, and billfish; tuna is a significant source of foreign exchange for a number of countries.

Various kinds of human activities are harming biodiversity in terms of habitat loss and degradation, resulting in, for example, loss of medicinal and aromatic plants of high value. Cultivation is perhaps the most significant cause of damage to ecosystems, involving large land areas and alteration of the landscape. The savannah was also greatly enlarged (usually at the cost of forests) through burning to improve grazing for livestock and to facilitate wild game hunting, forest clearance, and massive increases in the number of cattle (WCMC, 1992).
The margins of the seas are affected by humans almost everywhere. Habitats are being lost forever to the construction of harbours and industrial installations, the development of tourist facilities and mariculture, and the growth of settlements and cities. Increasing coastal erosion as well as pollution is also evident.

The adverse effects of poverty on biological resources are compounded by exploitation by a small but influential and affluent segment of the African population and by commercial firms hastening to satisfy market demands that often originate in other regions (UNEP, 1994).

African countries have taken steps over the years to conserve their biodiversity in its various forms. Protected areas have been established, for example, although they do not cover the full spectrum of biodiversity in the major ecosystems. The continent has 727 protected terrestrial areas (approximately 5 per cent of the total land area) and 112 protected marine areas (WRI/UNEP/ UNDP/WB, 1996).

A few countries (in particular, Kenya, Zimbabwe, and South Africa) have used one aspect of biodiversity-wildlife-for tourism development. Africa's share of international tourism was only 2 per cent in 1990 (World Bank, 1995), but it is a growing economic activity: for example, in southern Africa the number of tourists doubled between 1990 and 1994, and tourism contributed to about 3.4 per cent of the region's economy in 1994 (Hulme, 1996).

Although Africa's biodiversity generates considerable revenue, both for Governments and businesses as well as for industrial countries' commercial interests, more equitable distribution of these revenues to landowners adjacent to protected areas is needed to ensure the full and effective participation of local populations in the tasks of conservation and sustainable use of biological resources (UNDP/FAO, 1980; Makombe, 1993).