Multiple use of rangelands within agropastoral systems in southern Mali

The communal rangelands in southern Mali constitute important grazing areas, provide fruit, timber and fuel and protect the cultivated fields against run off. During recent decades the rangelands experienced increased pressure caused by periods of droughts, growth of the human and livestock population and an encroaching cropping system. This thesis focuses on various aspects of relevance to the condition of the rangelands. The main findings were: 1) that the condition of the rangelands with regard to their multiple functions has declined since recent decades, 2) that animal productivity is increasingly dependent on the cropping system and 3) that the influence of the cropping system on animal productivity leads to the deterioration of the rangelands.

The suitability for this region of a recently developed method to estimate primary production in Sahelian countries was analyzed by the comparison of measured and theoretical data. Consistent differences were found. Changes in the vegetation were presumably caused by recent droughts and increased exploitation.

The impact of the multiple forms of exploitation of the woody vegetation was investigated. Species were classified according to growth form and use for fruit, browse, timber and fuel wood. Of each species the contribution to accumulative canopy cover and abundance was determined. The contribution of more useful species generally was lower when the exploitation pressure was high. Tree species fulfilled more often several uses at the same time than did shrubs.

The influence of nutritional factors on seasonal -and relative palatability of browse species was investigated. It was found that the highest N and P concentration of DM of browse occurred during the season of browse consumption, while the most palatable species showed the highest concentration. More palatable species were also more deciduous than less palatable species.

The importance of the cropping system on animal production was shown by observations on seasonal fodder availability and consumption, farmers intervention, and liveweight changes of sedentary cattle. Farmers attitude towards the use of crop residues was related to land tenure, climate and cattle density.

A comparison of measured and simulated liveweight changes of cattle showed that consumption of crop residues is of vital importance to animal production. Correspondingly, the availability of crop residues determined the grazing capacity during the dry season. This grazing capacity may result in an overgrazing of the rangelands.

Finally the decline of the condition of the rangelands was described and attributed to recent droughts and increased exploitation. A suggestion to the development of a method to evaluate multifunctional rangelands is given and the interdependence of crop and livestock systems and the causes of the over-exploitation of the ecosystem are discussed. It is highlighted that macro-economic changes together which changes in land use management, social security and education are indispensable to develop a more sustainable land use system. A suggestion to an alternative land use system is presented.