Abstract

Natural vegetation of the western Butana plain of Sudan, at 14 to 16°N and 33 to 35’E, which is composed mostly of Acacia of the Mimosaceane family, has undergone dynamic changes during the last decades as demonstrated by a survey carried out in 2005. The majority of the vegetation is of Acacia trees, shrubs and grasses which are differing spatially, by soil type and in cover; frequency; abundance and density. There was a vegetation climax prior to 1850, while its dynamic changes took place through four successive stages. The ecosystem carrying capacity of the study area was adequate to support natural vegetation up to the year 1900, when human exploitation of vegetations was balancing with their growth. Ecological disequilibrium started directly after 1970 and manifested by declining ecosystem carrying capacity, dynamic changes and deterioration of vegetation. This dynamic change appears to be linked with the reduction in average annual rainfall. This paper demonstrates that, though important, this factor is not the sole, and may not even be the main factor involved. Government investment policy and associated population activities including, for example agricultural expansion which contributed 40% in vegetation change and deterioration and fuel wood by 30%, are shown to have great significance, and cast doubt to any belief that, a return to higher rainfall levels would reverse the current changes and deterioration processes.

Key words: Acacia, vegetation change, succession, deterioration, Butana, rainfall fluctuation, Sahel zone, rain-fed agriculture, human factors, community education.