Vegetation Structure in the Southern Kalahari

(1) Environment and vegetation-types of the southern Kalahari are briefly outlined, with reference to earlier work. (2) Principal components analysis of floristic data indicated one overriding factor-complex of differences in soil-types as the main source of vegetational variation. (3) PCA of life-form data resulted in a clear separation of the savanna, dwarf-shrub, and grassland or steppe communities. The main structural variation is explained by the distribution of the therophytes and hemicryptophytes, locally the most important life-forms and also the most important competitors for soil moisture. (4) Competition is most moderate in the savanna communities, which show the greatest variety in community-types, and could be expected to be most severe in the dry river-bed grassland; but the special soil conditions in this azonal habitat make avoidance of severe competition possible.