Plant Form in the Mountains of the Cape, South Africa

(1) Plant form and environmental data were recorded in 507 plots (each 10 m x 5 m) in the mountains of the Cape, South Africa. (2) Three groups of plant-form variables were identified in a principal components analysis. Group A variables (e.g. succulence, deciduousness, annuals, grasses) are characteristic of nutrient-rich or xeric sites or both. Group B variables (e.g. large leaf sizes) are also characteristic of nutrient-rich soils but are associated with mesic sites. Group C variables (e.g. ericaceous woody plants, evergreen geophytes, evergreen graminoids) are associated with nutrient-poor mesic sites. (3) A direct ordination analysis indicated that many plant-form variables did not show xeric-mesic trends; the abundance of many variables was related to the dichotomy between fynbos vegetation and non-fynbos vegetation (a dichotomy which is largely determined by soil nutrient status). (4) Many of the characteristic features of the predominant Cape vegetation, fynbos, e.g. low plant stature and pronounced evergreenness, scleromorphy and leptophylly, can be interpreted in terms of the nutrient-poor soils on which fynbos occurs, rather than in terms of other environmental factors. Similarly, most of the non-convergences between fynbos and the mediterranean vegetation of California and Chile can be explained by the more nutrient-poor soils of the Cape.