Fuzzy set analysis of the Ethiopian rift valley vegetation in relation to anthropogenic influences

Vegetation data of the Rift Valley have been revisited using fuzzy set theory to give quantitative measures of the links between species and vegetation states. Vegetation is considered as a global indicator of both land use and natural conditions. Human activities in the area have influenced the physiognomy of vegetation so much that an apparently uniform state has developed over most of the Rift Valley floor. Fuzzy set theory has made it possible to interpret the pattern of variation in vegetation on the basis of some reference states corresponding to protected and cultivated sites. The concept of stratocoena is applied to analyse the anthropogenic influences on the tree-shrub and herb layers in order to investigate how they respond to human interference individually.