SHIFTING SAVANNA

The Savanna Biome is as typical of Africa as the herds of game that it supports. The term Savanna describes a wide range of vegetation types, from the arid camel-thorn veld of the Kalahari to the bushveld and the coastal woodlands of KwaZulu-Natal. As climate changes, there may be a major rearrangement of plant species from these various savanna vegetation types. Some species may disappear altogether, while the distribution ranges of others may shrink or expand. For example, as the temperature rises, some lowveld plants like the tree wisteria (Bolusanthus speciosus) may be able to spread to higher altitudes along the edge of the escarpment. As previously mentioned, trees and shrubs from the Savanna Biome may start encroaching into what is currently the Grassland Biome. The mopane tree (Colophospermum mopane) is one species that is predicted to extend its range substantially in the Northern Province and Mpumalanga lowveld. The maps show that mopane trees could colonise the southern parts of the Kruger National Park. This is bad news for tourism because, although mopane woodland supports large numbers of elephants, it does not favour the diversity of large mammals that most tourists visit the Park to see.

In South Africa, Savanna is found mainly in the north and east but it is also widespread north of the border, where some types of savanna vegetation occur in warmer and drier climates than are typical of most of its South African distribution. As the climate changes, Savanna as we know it in South Africa may retreat from the northern and eastern borders of the country and be replaced by plants adapted to hotter and drier conditions further north. The Miombo woodlands of Zimbabwe and other parts of south-central Africa were previously thought not to occur anywhere else in South Africa. However, the Msasa (Brachystegia spiciformis), a typical Miombo woodland tree, has very recently been discovered in a tiny area of the Northern Province. The study shows that this plant was indeed expected to occur in small numbers in South Africa and that the future climate in large parts of the Northern Province and Mpumalanga will potentially be able to support Miombo woodland, as it expands from its present remnant population.