The Cape Floristic Region
The Cape Floristic Region of South Africa is famed for its plant richness and diverse habitats. It is a land of ecological extremesfierce gales, drought, deluge, fire and ice. One has only to mention the words Cape or fynbos (the most widespread Cape vegetation type) in the company of botanists, for a conversation to become laced with superlativesthe smallest floral kingdom of any temperate region, richest concentration of threatened plant species on Earth and worlds hottest hotspot of biological diversity are some of the free-flowing descriptions that have been applied to this biologically unique region. What is the Cape Floristic Region, and why has it captured the imagination of the botanical world?
Located at the southwestern corner of Africa, the Greater Cape Floristic Region is an L-shaped botanical province averaging only 100 km in width. It stretches about 500 km along the south coast of South Africa from Cape Town to Port Elizabeth, and a further 250 km northward from Cape Town to the semi-arid Namaqualand region. Some 9000 plant species are crowded into this small area comprising just 0.5% of the land area of the African continent. Amazingly, almost 70% of species in the Cape flora are found here and nowhere else on Earth . . .
The Cape flora
he flora of the Cape region would have been well known to its indigenous peoples, the San hunter-gatherers and the Khoekhoe herders. Although little remains of these cultures with their unwritten knowledge of plants, the rich indigenous knowledge is reflected in the Khoe-San common names of many taxa and ethnobotanical records of their use. That intimate plant lore or knowledge of the veld, and its medicinal and food plants, continues to be promoted mainly among rural communities. Our taxonomic knowledge begins with the specimens and writings of European explorer-naturalists who, from the 17th century onwards, began to document the remarkable richness of the Cape Flora. Their discoveries coincided with the revolutionary new methods of botanical classification developed by the innovative Swedish scientist Carl Linnaeus. At this time, the hinterland was insufficiently explored for the Cape Floristic Region as it is known today to be identified as a distinct botanical province and one of the worlds six plant kingdoms. Indeed, it was only in the late-20th century that the unique status of the Cape flora within a global context was formally recognised due to its floral richness and high levels of endemism. The flora contains about 9000 vascular plant species of which 69% are endemic (i.e. confined to the Cape Floristic Region). There are also about 160 genera and five families that are endemic to the region . . .
Biomes and vegetation
Ecologists have long recognised four major biomes (eco-regions) within the CFR. The Fynbos Biome encompasses the fire-prone fynbos and renosterveld vegetation communities and the strandveld, while the Succulent Karoo, Albany Thicket and Forest Biomes each correspond with a single major type of vegetation. Thus there are six main vegetation types in the CFR, each corresponding to a unique combination of soil and climatic features.
In this section, it is shown that these six vegetation types differ strongly in their ecology (e.g. some are fire-prone, while others are not), and thus Cape orchids show different adaptations according to the vegetation type in which they are found.
The shaping of the physical landscape
In this section, we briefly trace the geological history of the Cape, a region of dramatic physical contrastsjagged peaks and coastal plains, nutrient-poor white sands and nutrient rich clays, forests drenched in mist and sun-baked succulent vegetation. The shaping of this land has taken hundreds of millions of years of sedimentation, erosion and continental uplift, and a climate which has oscillated wildly between warm and dry, and cold and wet.
The orchid flora
n terms of its orchid species, Africa is the poor continental cousin of the Americas and Asia. The total African orchid flora probably numbers fewer than 2000 species, compared with around 8300 species in tropical America and 6800 species in tropical Asia. For reasons that are not yet fully understood, the tropical forests of Africa have not accumulated anything like the astounding numbers of epiphytic orchid species that occur in other tropical regions. However, for a temperate region, southern Africa, with about 470 mostly terrestrial orchid species, has a rich orchid flora in terms of species richness.
Orchids have not only gained a foothold in the Cape region at the southwestern corner of the continent and flourished on account of unusual strategies they have evolved for survival in this harsh environment of ecological extremes. We currently recognise 241 native orchid species as belonging to the Cape flora with certainly more to be discovered. Given the relatively small area of the Cape Floristic Region, this is an unusually high number of species for a temperate region . . .
This section discusses the tribal and generic relationships of the Cape orchids, with a summary and discussion of their latest published classification. Their evolutionary history and endemism within the Cape region is discussed in depth.
Conservation of orchids and their habitats
Some of the greatest losses of orchid habitat have occurred on the lowlands of the Cape Floristic Region. The status of natural ecosystems in the Cape Floristic Region, many now lost or threatened through the unrelenting land-altering pressures of mankind, are discussed. Aware of the perilous state of natural ecosystems in South Africa, this book uses the biology of orchids as a means by which to enlighten the broader public about the natural role of fire in fynbos and renosterveld ecology and environmental threats posed through overly frequent burning of habitats, urbanisation, poor agricultural practices and infesting alien vegetation.