Savanna Biome is the largest Biome in southern Africa, occupying
46% of its area, and over one-third the area of South Africa. It
is well developed over the lowveld and Kalahari region of South
Africa and is also the dominant vegetation in Botswana, Namibia
It is characterized by a grassy ground layer and a distinct upper
layer of woody plants. Where this upper layer is near the ground
the vegetation may be referred to as Shrubveld, where it is dense
as Woodland, and the intermediate stages are locally known as Bushveld.
The environmental factors delimiting the biome are complex: altitude
ranges from sea level to 2 000 m; rainfall varies from 235 to 1
000 mm per year; frost may occur from 0 to 120 days per year; and
almost every major geological and soil type occurs within the biome.
A major factor delimiting the biome is the lack of sufficient rainfall
which prevents the upper layer from dominating, coupled with fires
and grazing, which keep the grass layer dominant. Summer rainfall
is essential for the grass dominance, which, with its fine material,
fuels near-annual fires. In fact, almost all species are adapted
to survive fires, usually with less than 10% of plants, both in
the grass and tree layer, killed by fire. Even with severe burning,
most species can resprout from the stem bases.
The grass layer is dominated by C 4-type grasses, which are at
an advantage where the growing season is hot, but where rainfall
has a stronger winter component, C 3-type grasses dominate.
The shrub-tree layer may vary from 1 to 20 m in height, but in
Bushveld typically varies from 3 to 7 m. The shrub-tree element
may come to dominate the vegetation in areas which are being overgrazed.
Most of the savanna vegetation types are used for grazing, mainly
by cattle or game. In the southernmost savanna types, goats are
the major stock. In some types crops and subtropical fruit are cultivated.
These mainly include the Clay Thorn Bushveld (14), parts of Mixed
Bushveld (18), and Sweet Lowveld Bushveld (21). Urbanization is
not a problem, perhaps because the hot, moist climate and diseases
(sleeping sickness, malaria) hindered urban development.
Conservation of savanna is good in principle, mainly due to the
presence of the Kruger and Kalahari Gemsbok National Parks within
the biome. Similarly, in neighbouring countries, large reserves
occur, such as Etosha, Gemsbok, Chobe and Hwange National Parks
and the Central Kalahari Game Reserve. However, this high area conserved
in South Africa, belies the fact that half of savanna vegetation
types are inadequately conserved, in having less than 5% of their
area in reserves. However, much of the area is used for game-farming
and can thus be considered effectively preserved, provided that
sustainable stocking levels are maintained. The importance of tourism
and big game hunting in the conservation of the area must not be