The vegetation of the Samburu–Isiolo Game Reserve

Summary (1) Communities were identified in the field from presence/absence records of species using a form of progressive approximation. These communities were then mapped from aerial photographs of the Reserve area and boundaries were later checked on the ground. The quantitative characteristics of the communities were described in terms of cover and frequency. (2) The data were subjected to standard computer analyses and these results are used in an assessment of the validity of the original subjective techniques. (3) A hypothetical scheme is suggested which explains the principal lines of vegetation variation in terms of water availability and soil salinity. A number of related vegetation catenae may be recognized in addition to an east–west trend of increasing tree cover which is attributed to decreasing salinity along the riverine strip. (4) It is concluded that the effects of grazing and burning regimes are superimposed upon those of the physical environment and that further rapid changes in vegetation composition will take place within the next few decades.