Plant ecophysiological diversity
Oxford University Press
Faculty of Health, Engineering and Science
School of Natural Sciences/Centre for Ecosystem Management
The species richness of the Cape Floristic Region (CFR) reflects a complex evolutionary history as well as extreme habitat heterogeneity. This chapter argues that two main components of habitat heterogeneity are (1) the variability across the CFR in the prevalence of hot, dry summers and wet winters and (2) the edaphic diversity due the complex geological development of the CFR resulting in juxtaposition of relatively nutrient-rich and nutrient-poor soils. In addition, fire frequency/intensity is topographically and climatically determined and flammability is an important emergent property of some components of CFR vegetation. These sources of heterogeneity, together with biotic interactions (not explored in this chapter) are responsible for maintaining high niche diversity, which has driven a large number of ecophysiological specializations in the flora. These include specializations for the acquisition of resources, e.g. cluster roots to acquire P, succulence to store ephemerally available water, and conservation of resources, e.g. sclerophylly to conserve nutrients, small leaves to conserve water during summer. This chapter argues that the high diversity of ecophysiological niches in the CFR is important in maintaining species richness of the CFR.