ENDEMISM The endemism of vascular plants in southern Africa is exceptionally high, and more like what you expect on an oceanic island. This is attributable to diverse ecological conditions that has resulted in high speciation within genera (species to genus ratio is 9.6) paralleling the product of adaptive radiation occurring on oceanic islands. Genera with many species are mostly found in Fynbos and Succulent Karoo biomes. Compared to the global flora the southern African flora comprises a distinct phylogenetic sequence.
Transcript
ENDEMISM
The endemism of vascular plants in southern Africa is exceptionally high, and more like what you expect on an oceanic island.
This is attributable to diverse ecological conditions that has resulted in high speciation within genera (species to genus ratio is 9.6) paralleling the product of adaptive radiation occurring on oceanic islands.
Genera with many species are mostly found in Fynbos and Succulent Karoo biomes.
Compared to the global flora the southern African flora comprises a distinct phylogenetic sequence.
The southern African flora contains most of the world's species of Mesembryanthemumaceae (now Azoaceae), Ericaceae, Amaryllidaceae, Iridaceae, and Restionaceae, as well as high proportions of Geraniaceae, Proteaceae and Rutaceae.
The southern African flora has 13 endemic or near endemic families (with the revised classification – in press – this is reduced to 6 or 7).
Most of the endemic families are/were monogeneric, and mostly all are restricted to the winter rainfall regions (the CFR).
Biodiversity is not evenly distributed e.g. CFR covering 3.5% of the region has 41% of the species.
Endemism, based on the IUCN centre of plant diversity project, ranges from 4% to 68% - which compares with tropical rainforest of 44%.
The Cape with 6 000 endemic spp. is the hottest hotspot, and the Succulent Karoo with 1 600 endemic spp. is the only semi-arid area that is a global hot spot.
8830 endemic spp. and exceptionally high spp. to genus ratios of southern Africa is one of the most important areas for biodiversity conservation action.
CONSERVATION STATUS
The protected area network in South Africa is not optimally located with respect to hotspots, plant diversity and endemism. Reasonably large conservation areas exist for Wolkberg and Maputaland.
Mountain areas of the Cape are well conserved. The succulent Karoo is desperately poor as are the lowlands of the Cape Floristic region. Conserved areas and number of Red Data Book (RDB) taxa in southern African centres follow …
α = within plot/site/stand biodiversity. E.g. CFNR plots for species area, i.e. the number of spp. in one sample of a community.
β = within community biodiversity. E.g. Between several plots in the same community/stand, i.e. the number of spp. in the whole community, or the rate of change as one moves through the community (within community change-over).
γ = within landscape biodiversity. E.g. Taking plots from the whole of the CFNR, or along an altitudinal gradient, i.e. the rates of spp. change over from one community to another in the same landscape.
δ = between landscapes e.g. Comparing the Cape Peninsula and Kogleberg, i.e. beween geographic regions.
