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Succulent-Karoo
Biome has an equal status to the other biomes in
South Africa - it is not a subtype of "a Karoo
Biome." Most of the biome covers a flat to gently
undulating plain, with some hilly and "broken" veld,
mostly situated to the west and south of the
escarpment, and north of the Cape Fold Belt. The
altitude is mostly below 800m, but in the east it
may reach 1,500m.
A variety of geological units occur in the
region. There is little difference between the soils
of the Succulent Karoo and Nama Karoo Biomes - both
are lime-rich, weakly developed soils on rock. The
Olifants and Doring Rivers are the major drainage
systems in the west, with the Gouritz River in the
south-east of the biome. The Succulent Karoo Biome
is primarily determined by the presence of low
winter rainfall and extreme summer aridity. Rainfall
varies between 20 and 290mm per year.
Because the rains are cyclonic, and not due to
thunder-storms, the erosive power is far less than
of the summer rainfall biomes. During summer,
temperatures in excess of 40C are common. Fog is
common nearer the coast. Frost is infrequent.
Desiccating, hot, Berg Winds may occur throughout
the year.
The vegetation is dominated by dwarf, succulent
shrubs, of which the Vygies (Mesembryanthemaceae)
and Stonecrops (Crassulaceae) are particularly
prominent. Mass flowering displays of annuals
(mainly Daisies Asteraceae) occur in spring, often
on degraded or fallow lands. Grasses are rare,
except in some sandy areas, and are of the C3 type.
The number of plant species mostly succulents - is
very high and unparalleled elsewhere in the world
for an and area of this size.
Lekker Links
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Little data are available for the fauna
of the Succulent Karoo. Of importance in the
area are "heuweltjies", raised mounds of
calcium-rich soil, thought to have been
created by termites. These often support
distinctive plant communities.
The area has little agricultural
potential due to the lack of water. The
paucity of grasses limits grazing, and the
low carrying capacity requires extensive
supplementary feeds. Much soil has been lost
from the biome, through sheet erosion, as a
consequence of nearly 200 years of grazing.
Ostrich farming, with considerable
supplementary feeding, is practised in the
Little Karoo in the south of the biome.
In areas adjoining the Fynbos Biome,
wine grapes, fruit and other crops are
cultivated using the Fynbos water
catchments. Tourism is a major industry:
both the coastal scenery and the spring mass
flower displays are draw cards. Mining is
important, especially in the north.
Less than 0.5% of the area of the
Succulent Karoo Biome has been formally
conserved. The biome has a high number of
rare and Red Data Book plant species. The
high species richness and unique global
status of the biome require urgent
conservation attention. Fortunately, there,
are few invasive alien plants, with only
Rooikrans Acacia cyclops a major problem in
the southern coastal regions.
(Source: "The Vegetation of South
Africa, Lesotho and Swaziland", South Africa
Department of Environmental Affairs and
Tourism)
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