Rangeland Productivity and Exploitation in the Sahel

Abstract

Programs to develop the traditional livestock farming of the Sahel have often been ineffective despite great human and financial contributions. Efforts directed at better pasture and herd management, pasture improvement. livestock fattening, and increased marketing, have failed to improve the overall productivity of the herds and to stop range deterioration. A major reason is that many of ophy that the problems have to be solved primarily by preventing overgrazing, since at present the climate cannot be influenced and irrigation can only be used locally. Smaller herds and the development of areas of nonuse (wells). in addition to improvement of the herd composition and animal health, will improve the output of livestock farming. Future good management of the rangeSummary. Results of a Malian-Dutch research project on the Sahelian pastures and their utilization suggest reasons why some efforts to develop traditional livestock farming in this area have been unsuccessful. Failure to appreciate the effects of low soil fertility as well as low rainfall on pasture production has tesulted in underestimation of the productivity of the nomadic and semi nomadic livestock farming system and overestimation of the possibilities for increasing production by better management and by modernization.

Disentangling the Relationships between Net Primary Production and Precipitation in Southern Africa Savannas Using Satellite Observations from 1982 to 2010

“…Whether this range is applicable to other savanna ecosystems still needs further research. For example, Breman and Dewit [50] states that the proportionality breaks down at a precipitation of 300 mm·yr…”

Assessing Land Degradation/Recovery in the African Sahel from Long-Term Earth Observation Based Primary Productivity and Precipitation Relationships

“…The exact interval of annual precipitation in which proportionality may be assumed is debated. Hein et al [21] cites Breman & Dewit [25] for the statement that the proportionality breaks down already at a precipitation of 300 mm per year. They further suggest that a quadratic or cubic relationship might replace the assumption of proportionality when going beyond 200-300 mm precipitation.…”

Sahelian Rangeland Development; A Catastrophe?

“…The state variable is the vegetation community. It can be expressed by the mean annual biomass production because the production of each type of plant community (vegetation state) can be categorized in a specific yearly biomass production class, as can be deduced from data from Breman et al (1980) and Breman and De Wit (1983). Note that the term "state variable" has been adopted from catastrophe theory, while the term "vegetation state" has been taken from the state-and-transition formulation.…”

“…This process has been accompanied by a greater exposure of bare soil, leading to increased soil erosion and reduced infiltration of water in the soil. Subsequent removal of grazing or the occurrence of a succession of wet years after the &ought have rarely enabled the vegetation to revert to its former floristic composition and biomass (Walker et al 1981, Breman and De Wit 1983, Sincair and Fryxelll985, L.e Hou&ou 1989.…”

“…This implies an equilibrium. Particular vegetation states of communities of annual grasses or annual herbs (state II or state Ill) can persist over decades under moderate or high grazing intensities (Breman and Cisse 1977, Wickens and White 1979, Walker et al 1981, Breman and De Wit 1983, Sincair and Fryxell 1985, Le Houdrou 1989. Because these communities can survive over a much longer period than their turnover time, this also implies system equilibria (Connell and Sousa 1983).…”