干旱区生态环境知识资源中心

In a broad sense, land degradation in pastoral ecosystems leads to a reduction in primary vegetative yield and thus desertification, resulting in a major imbalance between animals and rangeland. Nomadism and transhumance are the two major livestock production systems of northern Cameroon. These production systems were relatively well adapted to the fluctuating sub-Sahelian environment of the region until 1979, when Maga Dam was built to store water for a rice irrigation project. This dam now prevents the normal flooding of dry season grazing land for livestock and wildlife and has induced large-scale desertification. Investigations in the region found that wildlife and pastoralists have adjusted to the new conditions. Besides herd diversification, which is an ecological as well as an economic-based strategy, herders implemented resource exploitation mobility in response to unpredictable forage and water availability. Pastoralists and wildlife equally developed escape mobility involving long-distance migration to elude the combined effect of range degradation and decreased rainfall. All these strategies were implemented as an adaptation mechanism against desertification. Although these strategies may have reduced the scope of livestock and wildlife mortality in the region, they have seriously affected the economy and increased the difficulties of the pastoralist way of life. (C)1998 Academic Press Limited.