A
frica’s plurality reflects that of
its landscapes. It lies astride the
equator, bounded beyond the
tropics at 23° 27’N and 23° 27’S and has
a diversity of special areas ranging from
deserts to evergreen forests. Beyond the
tropics, at the edge of the Sahara desert
in the north and the Namib and Kalahari
deserts in the south, lie landscapes and
a Mediterranean climatic atmosphere,
placing Southern Africa and the Maghreb
or the ‘western peninsula’, that is to
say the west seen from Arabia, ‘
Jazîrat
al Maghrib
’, outside the tropical zone.
Between the Mediterranean and the
Sahara with the Hoggar and Tibesti
ranges and marked by vast stony plains
and immense sand dunes, the Atlas
Mountains rise to more than 4000 metres,
a kind of natural protection against
the advance of the desert but which is
nonetheless open to the Atlantic.
This part of Africa situated outside the
tropics is characterised by a recent
alpine fold and has the same physical and
geological structure as its counterpart
in the south, Southern Africa, whose
relief is more simple, consisting of an
inner plateau (veldt) at 700 to 2000 m
and bordering scarps separating it from
the coastal areas and in the south-east
forming the Drakensberg range, with
Thabana-Ntlenyana reaching 3482 m.
The Sahel with its vast steppe landscapes
is a helpless ‘embankment’ in the face
of the relentless advance of Saharan
sand, aggravated in the 1970s by terrible
drought. It separates the arid, desert
ecosystems in the north and the humid,
rainy savannah regions to the south.
Endogenous species
As it is between the Tropic of Cancer
and the Tropic of Capricorn, the climate
is tropical by definition. But other local
factors perturb the usual meaning given
to a classic tropical environment marked
by the movement in opposite directions
of heat and rain from the equator to the
tropical zones. Rainfall decreases while
the temperature rises; thermal amplitude
is smaller at the equator and greater
towards the tropics.
In addition, the mountain landscapes
in the heart of tropical Africa create
microclimates that remind one of the
weather and landscapes typical of
temperate latitudes:
- lower temperature with increasing
altitude;
- increased rainfall with the rising of
hill and mountain levels where appears
alpine grassland, while the vegetation
layers below are representative of the
different domains.
Elsewhere, in addition to the classic
typology of the tropical environment,
endogenous species, characteristic of
Africa, are present. Likewise, tropical
plants are sometimes found in cold
landscapes far from their usual
environment. This is the case of banana in
Iceland and in the Lebanese mountains,
for reasons of sunshine on the latter case
and thanks to a warm thermal inversion
layer in the former.
Water is also strongly present throughout
theAfricancontinent. Sometimesstretching
far inland, a network of watercourses,
lakes, rivers and lagoons corresponding
to characteristic geological formations
runs from the Mediterranean coast to the
Cape of Good Hope.
In addition to the great lakes Chad,
Malawi, Tanganyika and Victoria, large
rivers—the Congo, the Chambeshi,
the Zambezi—and others flow slowly
in evergreen forest where strong
precipitations cause frequent, practically
annual floods. Other rivers such as the
Niger and the Senegal flow far from
their sources and cross regions with less
rainfall, sometimes creating landscapes
of rare beauty with vast stretches of
water covered by aquatic plants that are
becoming increasingly invasive with the
artificialisation of the environment. They
form temporary shelters for migrating
birds that have crossed the Sahara and
are seeking a warmer climate during the
northern hemisphere winter.
‘Mother’ Nile, the longest river in the
world, flows east of the Sahara where a
few precious oases govern the daily lives
of a scattered population. The cradle of
one of the greatest civilisations, the Nile
is still the natural transition between the
great African rift and the Mediterranean.
Cold marine currents along the Atlantic
and Indian Ocean coasts—the Canary
Islands and Benguela—enhance the
presence of extremely diversified aquatic
fauna. Warm currents off Guinea,
Mozambique and Somalia are the main
i
Agriculture is Ethiopia’s most important economic sector, employing 80% of the work force.
At Lalibela airport (northern Ethiopia), tradition and high tech coexist.
© J.D. Dallet/Suds-Concepts
12 - Sustainable Development in Africa & Satellites
