|Sustaining the Future. Economic, Social, and Environmental Change in Sub-Saharan Africa (UNU, 1996, 365 p.)|
|Part 2: Environmental issues and futures|
|Drought, desertification, and water management in Sub-Saharan Africa|
Pressures from human and livestock populations coupled with the effect of recurrent drought have led to serious degradation of vegetation cover, erosion, and depletion of soil fertility on a large scale in many parts of Sub-Saharan Africa. Desertification, as this tragic land degradation is referred to, threatens the drylands of Sub-Saharan Africa in a larger proportion than any other region in the world. Once the vegetation cover is removed, the fragile soils are exposed to winds and battering rains. Erosion is inevitable. Early storms are often accompanied by strong winds. Wind speeds exceeding 100 km/hour have been recorded at ICRISAT Sahelian Centre in Niger. Blowing sand subjects seedlings to abrasion and often results in their being completely covered by sand, causing serious problems in crop establishment (Kalij and Hoogmoed 1993). In many areas this takes dramatic forms: shifting sand dunes that swamp villages and fields, formation of deep gullies, crusts that seal the soil surface and markedly increase runoff.
Desertification has been described as self-propagating (Harrison 1987): as expanding areas become useless for crops or livestock, the pressure on the islands of remaining fertility increases. Farming is taken beyond the limits of sustainable rain-fed agriculture. Whole families, sometimes whole villages, migrate to better-watered areas. There they begin the process of deforestation, overcultivation, and overgrazing anew.
Implications for development
The traditional solution
Over the centuries African pastoralists and farmers had developed efficient systems of land use compatible with their environment. For example, nomadic pastoralists traditionally moved with herds of animals to different areas of good grazing and water supply. With low stocking levels they were able to move to new areas before the reserves of any single area were depleted and the soil laid bare.
The parkland system of cropping under tree cover, a widely practised farming system in the Sahel, is probably the most elaborate traditional agro-forestry practice known today in any of the semi-arid zones of the world. In most instances, however, farmers have relied on natural processes for the regeneration of the woody component.
The current level of population pressure, however, precludes true nomadic grazing or passive reliance on natural regeneration to maintain adequate tree densities in the farmlands. Many of the traditional solutions are no longer viable. The severity of land degradation alerted the governments and the international community and led to the creation in 1973 of CILSS (Comite Permanent Inter-Etats de Lutte contre la Secheresse dans le Sahel). Major efforts by the international community to combat desertification include the 1977 UN Conference on Desertification in Nairobi, Kenya, the creation of the United Nations Sudano-Sahelian Office, and the agreement at the Rio Summit in 1992 to negotiate a convention on desertification. The agreement commits governments, relevant non-governmental organizations, and the scientific community to prepare and adopt an international convention to combat desertification in all affected areas of the world, particularly in Africa.
Technical interventions introduced so far to combat desertification have met with very limited success. Some of the reasons for this debacle include the misunderstanding of the nature of the problem, which was initially conceived solely as the responsibility of the government departments in charge of forestry; hence, the overemphasis on planting fast-growing species in woodlots and green belts. The failure properly to diagnose people's perception of the problem and to identify the felt needs of local populations fuelled antagonistic relationships between foresters and peasants. This was because modern forestry, contrary to traditional wisdom in the region, has been considered to be separate from agriculture and livestock. Harrison (1987) noted that "foresters viewed farmers and herders as vandals, destroyers of forests to be kept out at all costs. Peasants saw foresters as policemen who excluded them from land that was traditionally theirs to control and use. Under such conditions the forests did not flourish." I have expressed similar views elsewhere (Bonkoungou 1985, 1987, and 1990) and pointed out the risk of some foresters failing to see the people for the forest.
The situation described above explains many of the failures in the fight against desertification. Yet trees and shrubs have a crucial role to play in the future of farming and pastoralism in Africa, as is becoming convincingly clear from research results of the International Centre for Research in Agroforestry (ICRAF).
The potential of agro-forestry to combat desertification and sustain agricultural production
Baumer (1987) extensively discusses the potential of agro-forestry to combat desertification. As mentioned above, research results from ICRAF indicate that agro-forestry has great potential for mitigating tropical deforestation, land depletion, and rural poverty. Trees integrated with crops or livestock meet wider needs than do woodlots. If properly spaced and managed, they serve as windbreaks and shelterbelts. They mark boundaries and strengthen terraces. They supply not only fuel, timber, stakes, and poles but also cash crops, fodder, fruits, nuts, leaves, and pods for human and livestock feed, gums, and medicines. In addition to the above products and many others, trees and shrubs also render various services in environmental protection: shade, improvement of soil fertility, etc.
As Harrison (1987) so ably advocates, agro-forestry offers by far the speediest road to reforesting Africa. Many African farmers already practice one form or another of agro-forestry but have relied mostly on natural regeneration of woody species, which is no longer reliable because of the much-shortened fallow periods. The task ahead then, as Harrison (1987) puts it, is "to convert African farmers and herders from passive to active agroforesters; from users of selfplanted trees, to tree farmers."
ICRAF does just that. Established in 1978, with headquarters in Nairobi, Kenya, ICRAF implements research jointly with national institutions through networks associated with the major eco-regions. One such network, the agro-forestry research network for the SemiArid Lowlands of West Africa was launched in 1989 with the objective of generating appropriate agro-forestry technologies for the ecoregion and strengthening national agro-forestry research capabilities in the subregion.