|
The southern African savannas
extend from about 34oS in the
Eastern Cape, northward along
the eastern side of the subcontinent.
At about 26oS they spread westwards,
skirting the northern edge
of the Highveld Plateau at
Pretoria, across the Kalahari
to Namibia, and northward until
they meet the tropical forests
of central Africa. Savannas
grade continuously into the
arid shrublands of the Nama
Karoo in the Eastern and Northern
Cape Provinces of South Africa
and Namibia. The arid savannas
consist of the fine-leaved
savannas, which include the
Kalahari savanna and the Colophospermum
mopane savanna. The savanna
biome covers more than 30%
of the land surface of South
Africa.
The geology and soils of the
savanna biome are diverse.
Summer rainfall is on average <800
mm, and temperature extremes
range from –10oC to 46oC.
Mild frost occurs on an annual
basis, and severe frost every
few decades.
The characteristic features are
a grassy ground layer and a
distinct upper layer of woody
plants. Shrubveld refers to
savannas where the upper vegetation
layer is near the ground. Where
the vegetation is dense and
tall it is referred to as woodland,
and the intermediate stages
are known as bushveld.
Summer rainfall is essential
for the grass dominance. The
principle disturbance that
keeps trees from dominating
savannas is fire, and almost
all species are adapted to
survive fires.
The plant species richness and
the diversity of mammals, birds,
reptiles, amphibians and insects
in savannas are high. The diverse
array of herbivorous large
mammals, as well as grasshoppers,
play a significant role as
grazers in savannas.
The arid savannas are used for
grazing by cattle and game.
Tourism and big game hunting
is a growing industry and game
farming is contributing to
the conservation of our savannas.
Fuel wood is the principal
energy source in most southern
African households, and in
areas of the Kalahari the demand
may be exceeding the supply,
especially for camel thorn
wood.
|
