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The Desert Biome is essentially
the Namib Desert. It is a
coastal plain,
100-150 km wide, stretching
from southern Namibia to southern
Angola. The
southern part of the desert
is characterised by a spectacular
sea of linear and crescent-shaped
sand dunes (some
reach 300 m in height above
the desert floor).
The northward march of the
dunes is blocked
by the occasional flooding
of the Kuiseb River. North
of the Kuiseb,
the dunes give way to gravel
plains that are dotted with
inselbergs of granite, schist
and limestone.
The Namib Desert is
an extreme desert, with
a mean annual rainfall ranging
between 5 mm in the west and
85 m in the east. Coastal fog,
a characteristic feature of
the Namib, is the desert’s
crucial life-support system.
It is this fog that contributes
to the remarkably high
diversity of animal life
in this extremely arid
environment.
The vegetation of the Desert
Biome is characterised by theriophytes
that persist as seeds
through extended periods
of drought. After good
rainfall (at least 20
mm), the desert undergoes
an incredible transformation,
with an explosion of mainly Stipagrostis grasses.
Other interesting plants
of this desert include
the well-known Welwitschia
mirabilis, the camelthorn
tree Acacia erioloba,
various succulent plants,
and a magnificent diversity
of lichens.
Of the 89 desert
vertebrates that occur
in the Desert Biome, 29
are endemic. These include
many reptiles (23 of 42
are endemic), three endemic
mammals (a bat and two
gerbils) and three endemic
birds. The Namib Desert
is probably best known
for its very high species
richness of beetles, particularly
those belonging to the
family Tenebrionidae.
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