Kalahari

The Kalahari is an integral part of the larger 1,5² million km Kalahari Basin which includes the Okavango Delta and other wetland regions. It is a semi-desert region stretching for 500 000² kms across parts of Botswana, Namibia and South Africa. Its rainfall is between 125 and 250mm annually – this gets rapidly absorbed by the sand acting like a huge filter leaving hardly any surface water.

Most of Botswana and large parts of Namibia are part of the Kalahari basin.  The Kalahari sand dunes compose the largest continuous expanse of sand on earth of which some stretch westward into the Namib desert. Although the Sahara Desert is larger overall, sand dunes make up only about 15% of its area.

The dunes are covered with a variety of vegetation, including grass tussocks, shrubs, and deciduous trees that have evolved to make use of the area’s infrequent precipitation and often severe swings in temperature. In summer, the heat can exceed 45°C (115²F) but during winter nights temperatures drop as low as -15°C (7²F).

The best known of all Acacia tree species in the north and east is the camelthorn tree. It is endemic to the Kalahari and a crucial part of the desert ecosystem, manufacturing nutrients that encourage other plants to grow around its base and providing shade for animals. The weaver birds love it to built their egg-shape grass-woven nests.

Some of the other trees in this area are the shepherd’s tree, blackthorn, and silver cluster-leaf. In the drier southwest, vegetation and wildlife are much more sparse, but Hoodia cactus – used for thousands of years by the San people to ease hunger and thirst during long hunting trips – still maintains a foothold there. Hoodia in modern times has also become a source of certain medicines.