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Savannah 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 and
Zimbabwe.
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
2,000m; rainfall varies from 235 to 1,000mm 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.
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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
sprout from the stem bases.
The grass layer is dominated by C4-type
grasses, which are at an advantage where the
growing season is hot, but where rainfall
has a stronger winter component, C3-type
grasses dominate.
The shrub-tree layer may vary from 1 to
20m in height, but in Bushveld typically
varies from 3 to 7m. The shrub-tree element
may come to dominate the vegetation in areas
which are being overgrazed.
 Most of the savannah vegetation types
are used for grazing, mainly by cattle or
game. In the southernmost savannah types,
goats are the major stock. In some types
crops and subtropical fruit are cultivated.
These mainly include the Clay Thorn Bushveld,
parts of Mixed Bushveld, and Sweet Lowveld
Bushveld. Urbanisation is not a problem,
perhaps because the hot, moist climate and
diseases (sleeping sickness, malaria)
hindered urban development.
Conservation
of savannah is good in principle, mainly due
to the presence of the Kruger and Kgalagadi
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. This high
area conserved in South Africa, belies the
fact that half of savannah 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 underestimated.
(Source: "The Vegetation of South
Africa, Lesotho and Swaziland", South Africa
Department of Environmental Affairs and
Tourism)
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