South Africa’s Greater Cape Floristic Region

South Africa’s Greater Cape Floristic Region

Hugging the southwestern corner of Africa, a buffer of green separates the ocean from the arid South African interior. Contained within this relatively narrow band is the entirety of one of Earth’s six floral kingdoms, known as the Greater Cape Floristic Region.

The natural color image (left) was acquired by the VIIRS (Visible Infrared Imaging Radiometer Suite) sensor on the Suomi NPP satellite on October 2, 2023, and the map (right) outlines the extent of the floristic region—the smallest on Earth. To capture any of the other five such regions, a much wider view would be necessary. The Boreal kingdom, for example, occupies most of North America and Eurasia.

The Greater Cape Floristic Region is a hotspot of biodiversity containing thousands of plant species found nowhere else on the planet. It occupies less than 0.5 percent of the area of Africa but supports approximately 20 percent of its plant life. About two-thirds of the estimated 9,000 species that grow there are endemic. Because of its distinct, diverse, and abundant plant communities, the area is not only recognized as its own major floral kingdom, but a number of properties within it are also protected as UNESCO World Heritage sites, national parks, and nature reserves.

Most of the region is treeless and covered in a type of evergreen shrubland called fynbos. The fynbos teems with reeds, heathers, and succulents, as well as colorful orchids, lilies, and proteas. The king protea (Protea cynaroides, below), whose flower heads can reach 30 centimeters (12 inches) in diameter, is South Africa’s national flower and present throughout the fynbos.

If not for the profusion of life, the growing conditions in the Greater Cape Floristic Region might appear inhospitable. Fynbos plants are adapted to the Mediterranean climate of hot, dry summers and wet winters. They thrive in the sandy nutrient-poor soil, pummeled by wind and sun. What’s more, the health of the ecosystem is reliant upon the periodic fires that burn there, both for seed dispersal and germination and for killing off invasive species.

Crucially for the Cape Town area, the fynbos vegetation takes up very little water, allowing most precipitation to flow into rivers and reservoirs. The city is prone to water shortages and came perilously close to running out in 2018. Thirstier non-native trees such as acacia, pine, and eucalyptus have spread into the floristic region, threatening endemic species and using more water than native plants. Recent initiatives have focused on managing the invasive trees to increase the amount of water in the regional supply.

A NASA field campaign—conducted with SAEON (South African Environmental Observation Network), the University of Cape Town, and other South African partners—called BioSCape (Biodiversity Survey of the Cape) will help scientists better understand this biodiversity hotspot. Data collected with instruments on NASA aircraft during several weeks in autumn 2023 will be combined with satellite and field observations, providing insight into the structure, composition, function, and threats to the region’s biodiversity.

NASA Earth Observatory images by Wanmei Liang, using VIIRS data from NASA EOSDIS LANCE, GIBS/Worldview, and the Suomi National Polar-orbiting Partnership. Boundary data from the Critical Ecosystem Partnership Fund, Conservation International. Photo from PxHere. Story by Lindsey Doermann.

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