Central Africa is predominantly covered in forest and savanna. The coastal humid belt, with high and relatively constant rainfall, supports dense tropical forests, whereas the northern parts of Cameroon, Central African Republic and Chad are drier, with more variable rainfall, and the dominant vegetation is savanna. Land use in the sub-region is sensitive to climatic and vegetation characteristics, with forestry and commercial plantation agriculture largely found in the humid zones (where rainfall reaches up to 4000 mm/yr), and livestock rearing, with some subsistence cultivation, in the semi-arid zones (where rainfall averages 500 mm/yr). The semi-arid zone is also highly vulnerable to climatic variations and drought, which limit agricultural expansion. Soils are highly vulnerable to erosion, because most of the rainfall occurs in intense heavy storms, and because the clay and silt content makes the soils prone to crusting when exposed (Njinyam 1998).
Approximately 8 per cent of the total area is currently used for arable and permanent crops (with Cameroon having the largest share, at 15 per cent of its land area), and 16.5 per cent is used as permanent pasture (FAOSTAT 2001). Irrigated agriculture is limited, partly because the fertile soils and the high, reliable rainfall in the humid zone are conducive to rain-fed agriculture, and partly because the infrastructure development required to establish irrigated cultivation in the semi-arid zone has so far been prohibitively expensive. Despite these favourable conditions in central Africa, large-scale agricultural development has been limited by national market failures and international trade barriers. Shifting cultivation (or slash-and-burn agriculture) was a traditional means of coping with variability, but this practice is no longer sustainable, because there are much larger populations now requiring land. The priority issues in central Africa are, therefore: improving food security, through enhanced production and distribution of resources; and reducing the pressures that shifting cultivation has on forests and woodlands.
In 1970, 81 per cent of Central Africa's labour force was employed in agriculture, with Chad having the highest at 92 per cent. By 1980, the percentage had fallen to 74 and, in 1990, the average was 68 per cent (World Bank 2001). The reasons for this decline include population growth exceeding agricultural expansion, and industrial development. Pastures account for much of the agriculturally productive land in the Sahel, and pastoralists and agropastoralists are integral parts of local and regional economies. It was estimated in 1995 that there were more than 404 000 pastoralists in Chad (about 15 per cent of the country's population), with pasture areas covering about 55 percent of the national territory (FEWS 1995).
The major crops in the sub-region include: cassava; cocoa; coffee; cotton; groundnuts; maize; millet; palm oil; rubber; and sorghum. In 1980, the total value of agricultural exports for the region was US$1 148 million, although Cameroon took the lion's share at US$699 million. In 1990, exports fell to just US$909 million, mainly as a result of commodity price fluctuations (World Bank 2001). By 1997, however, markets had recovered in most countries, although the war in Democratic Republic of Congo had an enormous impact on its agricultural exports and, as a result, totals for the sub-region were just US$796 million (World Bank 2001). Value added in agriculture in 1980 ranged from 40 per cent of GDP in Chad to just 12 per cent in Gabon (World Bank 2001). In 1990, the percentage for Chad fell to 24 whilst, in Democratic Republic of Congo, the percentage contribution of agriculture to GDP has climbed from 27 in 1980 to 58 in 1999, mainly due to other economic activities having been disrupted due to the war (World Bank 2001).