Using the Proteaceae to Design a Nature Reserve Network and Determine Conservation Priorities for the Cape Floristic Region

Abstract

Abstract The Cape Floristic Region (CFR), covering 90 000 km2, comprises one of the world’s six floral kingdoms. With 8600 species, of which 68 per cent are endemic, it ranks amongst the richest of temperate and tropical floras, although most of the diversity is concentrated in a few speciose taxa. Some 19 per cent of the area of the CFR is in nature reserves, but by far the majority of the preserved area comprises mountain Fynbos. Fortunately Fynbos vegetation is the richest habitat for Red Data Book (RDB) plant, freshwater fish, amphibian, butterfly, and reptile species in southern Africa. However, only 3 per cent of the original extent of lowland Fynbos is preserved, with the greater Cape Town metropolitan area ranking globally as one of the most urgent conservation priorities. Previously used methods for evaluating priority conservation areas have underrated species-poor areas containing a high proportion of RDB species. By correcting for species richness, a far more realistic picture of threatened areas can be obtained from RDB taxa. Utilizing an iterative selection procedure to identify optimal reserve configurations, based on Proteaceae species richness, suggests that 95 per cent of all vascular plant species in Fynbos can be preserved in 16 per cent of the area. Two null models for evaluating the efficiency of a spatial configuration of reserves are proposed. These results suggest that the ideal approach to designing a reserve configuration is to identify areas of high endemism and richness in distinctive vegetation types within particular biogeographical regions. A priori hypotheses based on ecological traits indicate that seed dispersal and regeneration strategies are most strongly correlated with rarity, most specifically with distributional area.