Figure 35. GEZ map of Africa.
Table 20. Global Ecological Zones of Africa.
Surface area | |||
Km2 |
% of total land area Region |
% of GEZ worldtotal | |
Tropical rain forest |
4 017 705 |
13.5 |
27.6 |
Tropical moist deciduous forest |
4 661 180 |
15.6 |
42.2 |
Tropical dry forest |
3 669 529 |
12.3 |
49.1 |
Tropical shrubland |
5 977 939 |
20.0 |
71.9 |
Tropical desert |
8 737 674 |
29.3 |
75.5 |
Tropical mountain systems |
1 473 226 |
4.9 |
32.6 |
Subtropical humid forest |
85 099 |
0.3 |
1.8 |
Subtropical dry forest |
334 816 |
1.1 |
21.0 |
Subtropical steppe |
456 663 |
1.5 |
9.3 |
Subtropical desert |
0 |
0 |
0 |
Subtropical mountain systems |
412 356 |
1.4 |
8.5 |
Total land area |
29 826 187 |
99.9 |
|
Climate
This Ecological Zone covers the central part of Africa, on both sides of the Equator, as well as on the southeastern coasts of the continent. High rainfall, ranging from 1000 to more than 2000 mm/year, is due to the permanency of the Inter Tropical Convergence zone (ITC) on the Equator, or to the trade winds blowing from the south-east on the southern hemisphere (eastern coasts of Tanzania, Zimbabwe, Madagascar). The regime is more or less equatorial or tropical. If there is a dry season, it does not exceed 3 to 4 months and always occurs in winter. Temperature is always high in these low latitude areas, generally more than 20°C, except in the mountains, where it is lower, with still a low annual range.
Physiography
The Ecological Zone is underlain by the ancient rocks of the crystalline shield which only outcrop in the Cameroon and Madagascar highlands. Everywhere else, they are buried by younger sedimentary rocks in basins and upland plains mostly between 150 and 600 m above sea level, as well as coastal deposits. The Congo basin, dominating the central part of the zone, has an average altitude of 400 m and gradually rises to the uplands and plateaux which form its rim. In the basin the Precambrian rocks are covered by continental sediments ranging from Paleozoic to recent. Quaternary sediments cover the large alluvial plain in the centre of the basin where there are remnants of former lakes and extensive swamps. Surrounding the Congo basin are the equatorial uplands, a region of dissected plateaux which merge with it. Near the basin the plateaux are mostly composed of slightly metamorphic Upper Precambrian sandstone, quartzite and schist.
Vegetation
The greater part of the Ecological Zone was formerly covered with rain forest on well-drained sites and swamp forests on hydromorphic soils. Today, little undisturbed rain forest remains and secondary grassland and various stages of forest regrowth are extensive. In the mountains, lowland rain forest is replaced by dense ombrophilous low forest and various types of thicket.
In this large area, several Eco-Floristic Zones have been distinguished according to, either a more or less wet climate and with or without a dry season, or a distinctive flora. Regarding the flora, three blocks have to be separated: the Guineo-Congolian region of western and central Africa, with about 80% of endemic taxa; Madagascar (about 80% of endemic species) and the eastern coast of southern Africa. In the latter, linking elements with the two formers can be recorded. Compared to the rain forests of South America and Asia, African forests are relatively poor floristically. The density of tree species in various African lowland evergreen forests is much lower than has been recorded for forests in the other continents.
The most extensive formation is the Guineo-Congolian lowland rain forest, concentrated in the Congo basin: tall dense forest, more than 30 m high with emergents up to 50 – 60 m and several strata. Some canopy species are deciduous, but the forest is evergreen or semi-evergreen. Epiphytes are abundant, particularly in the wetter types. Main large trees include Entandophragma spp., Guarea cedrata, G. thompsonii, Lovoa trichilioides (all Meliaceae), Maranthes glabra (Chrysobalanaceae), Parkia bicolor (Leguminosae), Pericopsis elata (Leguminosae), Petersianthus macrocarpus (Lecythidaceae). Small patches of single dominant moist evergreen and semi-evergreen rain forest occur that are usually dominated by one or more of the following species of Leguminosae: Brachystegia laurentii, Cynometra alexandri, Gilbertiodendron dewevrei, Julbernardia seretii, Michelsonia microphylla.
The rain forest of Madagascar is 25-30 m tall, without large emergent trees. The forest is evergreen, with many palms, some bamboos and abundant epiphytes, especially epiphytic ferns and grows up to 800 to 1000 m altitude. This forest is very rich in species. Some of the important families represented in the upper canopy are Euphorbiaceae, Rubiaceae, Araliaceae, Ebenaceae (Diospyros), Sapindaceae, Burseraceae (Canarium), Anacardiaceae, Elaeocarpaceae (Echinocarpus), Lauraceae, Guttiferae, Myrtaceae, Malpighiaceae and the conspicuous giant monocot (Ravenala madagascariensis).
In the drier periphery of the zone, we find transitional forest types. These evergreen or semi-evergreen forests may be characterized in West Africa by the following tree species, absent from wetter types: Afzelia africana, Aningeria altissima, A. robusta, Chrysophyllum perpulchrum, Cola gigantea, Khaya grandifolia, Mansonia altissima. Other important species include: Triplochiton scleroxylon, Celtis mildbreadii, Holoptelea grandis, Sterculia spp., Trilepisium madagascariense, Chlorophora excelsa.
Mangroves extend along the muddy, sheltered coasts of the Gulf of Guinea from Angola up to Senegal. They are characterized by the following tree species: Rhizophora racemosa, R. harrisonii, R. mangle, Avicennia africana, A. nitida, Laguncularia racemosa and Acrostychum aureum.
Climate
Around the Guineo-Congolian basin, along the south-eastern coast of Africa, as well as in the central part of Madagascar, the wet zone is bordered by an area where the dry season is always pronounced, during up to 6 months. There is a single rainy season, in summer, but there are pronounced regional variations. Annual rainfall varies between 800 and 1500 mm, locally up to 2000 mm.
Physiography
To the south of the Guineo-Congolian basin, this GEZ lies on the Great African Plateau, the altitude of which is mostly 900-1000 m, up to 1500 m. In eastern Angola and Kwango, the Precambrian rocks of the plateau are covered by a thick mantle of Kalahari sands. To the north of the Guineo-Congolian basin, the gently undulating surfaces are nearly everywhere below 750 m altitude, except Jos and Mandara plateaux. Most of the soils are formed from Precambrian rocks. The coastal plain of southeastern Africa is underlain by marine sediments of various ages, from Secondary to recent. In Madagascar, this GEZ extends on the western side of the island up to about 800 m altitude. The greater part of the region is underlain by sediments of Secondary and Tertiary ages covering the crystalline Precambrian.
Vegetation
Several vegetation types exist together in this Ecological Zone. Forests formerly occurred on deep, freely drained soils. Their areas have greatly decreased due to fire and cultivation. Dry evergreen forest, which is a drier, simpler in structure and floristically poorer facies of rain forest, is widely distributed on Kalahari sands, with Marquesia, Berlinia, Laurea. Semi-evergreen forest of Guineo-Congolian type is mainly confined to Angola. On the eastern coastal plain, forest is the climax, but it has been largely replaced by wooded grassland and cultivation. The forest, due to change in amount and distribution of rainfall, dry season atmospheric humidity and the availability of soil moisture, changes rapidly in floristic composition and physiognomy. However, it is generally deciduous.
Everywhere else, the most widespread and characteristic vegetation type is woodland, namely Wetter Zambezian miombo woodland to the south, Sudanian woodlands to the north. Wetter miombo are characterized by several species of Brachystegia (B. floribunda, B. glaberrima, B. taxifolia, B. wangermeeana, B. spiciformis, B. longifolia, B. utilis), the canopy height being more than 15m, sometimes reaching a height of 30 m. Associate species include Marquesia macroura and Pterocarpus spp., Julbernardia, Isoberlinia. Sudanian woodlands, generally lower, are characterized by several species of Acacia and by the Leguminosae Isoberlinia doka. Beside the latter species, other characteristic species include Acacia dudgeonii, A. gourmaensis, Antidesma venosum, Faurea saligna, Lophira lanceolata, Maprounea africana, Maranthes polyandra, Monotes kerstingii, Ochna afzeli, O. schweinfurthiana, Protea madiensis, Terminalia gluacescens and Uapaca togoensis.
In Madagascar, primary vegetation is a dry deciduous forest or thicket, but the most extensive vegetation is secondary grassland. Nevertheless, some areas of dry deciduous forest remain, especially along the coast, with various facies depending on the soil: forest with Dalbergia on lateritic soils, Tamarindus indica on sandy soils, Adansonia, Bathiaea on calcareaous plateaux.
Mangroves occur along sheltered coasts of the Indian Ocean, dominated by Rhizophora mucronata, Avicennia marina and Sonneratia alba. Other tree and shrub species include Ceriops tagal, Bruguiera gymnorrhiza and Xylocarpus obovatus.
Climate
Still further from the Equator and from the wet southeastern coast, rainfall decreases and the dry season is always long, during 6-7 months. Rainfall varies between 500 and 1000 mm. Temperature is always high, with mean temperature of the coldest month?20°C. These conditions are also found in Ghana (Accra) and on the western coast of Africa (Cabinda): in Ghana, the wet winds blowing from the south-west do not reach the coast of Accra; in Cabinda, the Benguela Current induces low rains in the neighbour coast.
Physiography
To the south, this GEZ is an extension of Zambezian region. The flat surfaces of the Great African Plateau lie at more than 1000-1200 m. They are formed of a great variety of Precambrian rocks. The western limit of the plateau is an escarpment separating it from the coastal plain of Cretaceous and more recent sediments. To the north, it is also an extension of the previous south Sudanian region. This plain formed from Precambrian rocks is covered, on large areas of its eastern part, with recent deposits: consolidated dunes or clays.
Vegetation
In these drier conditions, the predominating vegetation type is woodland. In the Zambezian region: drier miombo, poorer than the wetter one, on the plateau; mopane (Colophospermum mopane) woodland or Sudanian woodland in the southern valleys and depressions; scrub woodlands with Acacia caffra, A. davy, A. luederitzii in the southern lowlands of the Ecological Zone. Grasslands occur on seasonally waterlogged soils. In the Sudanian region: woodlands with Acacia albida, A. macrostachya, A. nilotica; in Sudan, woodlands with Anogeissus leiocarpus and various species of Combretum. Where cultivation is possible, most of the land is bush fallow. Permanent or semi-permanent cultivation is being practiced around the large towns. Two specific Ecofloristic Zones have been defined in Accra plain and Cabinda. Near Accra, some patches of dry semi-evergreen forest with Diospyros abyssinica and Milletia thorningii remain and the drier parts are covered by sparse short grassland dotted with thicket clumps. In Cabinda, the prevalent vegetation is wooded grassland with Adansonia digitata and many individuals of Anacardium occidentale and Mangifera indica, two introduced trees. A conspicuous tree of this zone in Africa is the boabab (Adansonia digitata) with its bizarre big trunk.
Climate
In these areas close to the tropics, rainfall becomes lower and lower, when temperatures are still high. It is the case of the Sahelian zone and Kalahari, as well as the southwestern part of Madagascar. Rainfall is always less than 1000 mm and scarcely reaches 200 mm in the drier parts. Mean temperature of the coldest month is generally more than 20°C, except in Kalahari where, due to proximity of the sea, temperatures are lower (mean temperature of the coldest month may drop down to 10°C). Somalia is a special case: even if it lies across the Equator and not further than 12°N, the climate is semi-arid or arid. Whereas the trade winds direction is parallel to the coast and does not bring much humidity. Moreover, in winter, the Indian monsoon reaches this part of Africa after crossing large continents. As a result of these phenomena, Somalia is dry, with annual rainfall between 400 and 750 mm and very high temperatures due to low latitude.
Physiography
Most of the Sahel region forms a flat or gently undulating landscape below 600 m. Large areas are covered with Pleistocene clays or sand sheets. The Kalahari basin extends to the south of the Great Escarpment. It is filled with Tertiary sands and lies between 850 and 1000 m. Somalia is a low land extending from the sea level to about 900 m. Its underlying lithology is extremely diverse, with extensive areas of Secondary and lower Tertiary sediments and less extensive areas of tertiary and Pliocene lava flows. In Madagascar also, this GEZ corresponds with a wide plain formed of Secondary and Tertiary sediments.
Vegetation
In these very dry areas, spontaneous vegetation is generally pseudo-steppe, scrub woodland or thicket. In the Sahelian zone, which supports wooded grassland (mainly with Anogeissus and Acacia) in the south and semi-desert grassland in the north, pastoralism is the main land use. Pastoralism also prevails in Somalia, in predominating deciduous shrubland and thicket with Acacia and Commiphora.
In the Kalahari, stunted scrub woodland with acacia (Acacia karroo) and shrub pseudo-steppe form the landscape.
In Madagascar, even if dry deciduous forest still occurs on the northern part of the GEZ, the most characteristic vegetation type is the deciduous thicket with Didiereaceae. Extensive areas are covered with this thicket in the western part of the region, but the central plateau is mainly covered with dry savanna.
Climate
This Ecological Zone extends on the desertic African lands: Sahara, Karoo-Namib and the coastal zone of Somalia. There, rainfall is lower than 200 mm and does not allow growth of a continuous vegetation cover.
Physiography
The Sahara consists of several basins filled with Pleistocene deposits: sands or gravels. Between the depressions, Cretaceous and Tertiary deposits form a stone desert. The geology and physiography of the Karoo-Namib region is very diverse. In the interior of the Cape Province, the surface is formed of the Karoo system and is generally even. In the northwest, granite and other primitive rocks are exposed, with igneous intrusions, on the escarpment of the Great Interior Plateau. The Namib Desert lies on a coastal peneplain, extensive areas of which are covered with moving sand of recent origin.
Vegetation
Generally, only pseudo-steppe and shrub pseudo-steppe can be found in these areas, with woody vegetation concentrated along the wadis in Sahara. Large surfaces are true desert.
Climate
Above 800 to 1200 m, temperature decreases and vegetation changes. So, we defined submontane, montane and high elevation Ecofloristic Zones within each GEZ. All of them correspond with tropical vegetation types. The main mountains systems of tropical Africa are the Cameroon highlands, the mountains of Kenya, the Kivu ridge and Ethiopian highlands. Some lower and isolated hills occur, such as Fouta Djalon, Jos and Mandara plateaux in West Africa, Hoggar in Sahara or Windhoek Mountain in southern Africa. The central part of Madagascar is formed of a high range separating the western wide lowlands from the narrow eastern coastal plain. The climatic type of each mountain is close to that of the surrounding lowland, with lower temperatures and, often, higher rainfall.
Physiography
The physiography is very diverse. Most of the Ethiopian highlands are formed of basalt, though Precambrian rocks locally outcrop. The Kenya highlands are mostly formed of volcanic post-Miocene deposits; Cherangani Hills are composed of Precambrian metamorphic rocks. The Kivu ridge and contiguous uplands are largely composed of Precambrian rocks. The Cameroon highlands are formed partly of volcanic, partly of ancient crystalline rocks. Mount Cameroun is a still active volcano. In Madagascar, the central highlands are formed of the Basement complex of igneous and metamorphic rocks.
Vegetation
Also the vegetation is extremely diverse and varies with climate. On most mountains the lowermost vegetation is forest. Between the lowland forest and the rather different (in physiognomy and flora) montane forest, there is a submontane transition zone. In many places, however, the vegetation of this transition zone has been destroyed by fire and cultivation. Montane forest, generally above 1500-2000 m, is lower in structure than lowland and submontane forests. At the upper part of the montane level, an Ericaceous belt replaces the forest. Then, mostly above 3000 m, followed by Afro-alpine shrublands and grasslands.
In western Africa, on the Kivu ridge or on the wetter slopes of Ethiopian highlands and East African mountains, the rain forest is similar in structure and physiognomy to the lowland rain forest, but it is floristically different. The trees of the upper stratum are 25 – 45 m tall. Their crowns are raised well above the middle tree stratum and are heavy branched and wide-spreading. The middle tree stratum is 14-30 m tall, the lower tree layer at 6 – 15 m and often mixed with the shrub layer. Characteristic tree species of Afromontane rain forest include Aningeria adolfi-friedericii, Chrysophyllum gorungosanum, Cola greenwayi, Diospyros abyssinica, Drypetes gerrardii, Olea capensis, Podocarpus latifolius, Prunus africana, Syzigium guineense subsp. afromontanum and Xylamos monospora.
Bamboo (Arundinaria alpina) forest or thicket occurs on most of the high mountains in East Africa and sporadically on some of the mountains of Cameroon. It is mostly found between 2300 and 3000 m and appears to grow most vigorously and to form continuous stands on deep volcanic soils on gentle slopes where the rainfall exceeds 1250 mm per year.
In Madagascar, the original vegetation in the mountains was forest: moist montane forest with Tambourissa and Weinmannia and sclerophyllous montane forest with Dicoryphe and Tina on the eastern slopes, drier “tapia” (Uapaca bojeri) forest on the western slopes. Over extensive areas, these forests have been replaced by secondary grassland. Above 2000 m, the characteristic vegetation is montane thicket.
In some parts of western Africa (Jos and Mandara plateaux) as well as in Kenya, Burundi and in southwestern Ethiopian uplands, at medium elevation, bushland or thicket remains, transitional between Sudanian or Zambezian vegetation and montane forest.
In Ethiopia and Kenya, dry mountain vegetation types are extensive: evergreen or semi-evergreen shrubland and thicket (with Acacia, Carissa) at medium elevation and Juniperus procera forest at montane level in Ethiopia.
The mountains of the Sahara are semi-arid to arid, with little vegetation cover.
This Ecological Zone is restricted in Africa to a narrow zone along the east coast of Southern Africa, roughly between 25o and 34oS.
Climate
The coastal regions of the zone have a moderately high and well-distributed rainfall and, except in the extreme south are frost free. Annual rainfall is 800-1200 mm and mean temperature of the coldest month 7° to 15°C. Mean annual temperature diminishes from 22oC in the north to 17oC in the south. Further inland, climate changes rapidly over short distances.
Physiography
This narrow belt along the coast is formed of rocks of the Basement Complex, sandstones and sedimentary strata of the Karoo System. In the northern part, the plain is wider, up to 240 km, composed of Cretaceous and Tertiary marine sediments overlying the Basement.
Vegetation
In most of the Ecological Zone, the natural vegetation is evergreen or semi-evergreen forest, in some parts approaching rain forest in stature and structure. The canopy varies in height from 10 to 30 m or slightly more. The most luxuriant stands approach rain forest in stature and structure. The canopy is evergreen to semi-evergreen. About 120 species occur in the canopy, though normally not more than 30 would be present in any one stand. The flora is from various origins, with some endemic species like Atalaya natalensis, Anastrabe integerrima, Beilschmiedia natalensis, Brachylaena uniflora, Cola natalensis, Commiphora harveyi, Cordia caffra, Diospyros inhacaensis and Manilkara concolor. Today, where the original vegetation has not been completely replaced, land cover often consists of a mosaic of forest, scrub forest, bushland and thicket, with secondary grasslands.
Where the rainfall is too low to support forest, the most widespread climax vegetation is evergreen and semi-evergreen bushland and thicket. In the north this type is most extensively developed in the low-lying country between the forests of the coastal plain and the mountainous country inland. Further south it occupies deep valleys. The most widespread bushes, which grow 3-6 m tall, include among others Azima tetracantha, Bauhinia natalensis, Carissa bispinosa, Diospyros spp., Euclea spp., Maytenus spp., Olea africana, Phyllanthus verrucosus, Schotia spp. and Xeromphis rudis. Arborescent succulent species of Aloe and Euphorbia occur throughout. In the southern part, the vegetation becomes close to the Cape fynbos, a sclerophyllous shrubland with Leucadendron and Metalasia.
Climate
This Ecological Zone concerns the Mediterranean climates of North Africa and South Africa.
The dry season, more or less pronounced (3 to 6 months), is in summer, most of the rainfall (400-1000 mm/year) occurring in winter. The whole of northern Africa experiences this dry period. In South Africa however, only the Cape region has a typically Mediterranean climate; eastwards, the rains become more evenly distributed throughout the year (Subtropical Humid). The annual range of temperatures is rather high, but mean temperature of the coldest month, in lowlands, is always more than 7°C.
Physiography
In northern Africa, the Mediterranean zone is mostly the region of folded mountains at the northwestern extremity of the continent. The various ranges of the Atlas mountains are separated by plateaux and basins. A coastal lowland belt runs from the Atlantic coast to Egypt. Only the lowlands below 1000 m are included in the Ecological Zone. The lithology is diverse, but the prevalent rocks are Secondary or Tertiary sediments, sometimes metamorphosed.
In South Africa, the landscape is dominated by subparallel folded mountain ranges with an average altitude of 1000-1500 m. In the western part, the foothills and lower slopes are commonly formed of Cape granite. The valleys and parts of the coastal belt are formed from Palaeozoic shales and sandstones. The coastal fringe itself consists of Tertiary to recent sands, conglomerate and limestone.
Vegetation
In northern Africa, the climax vegetation is forest, with Quercus suber, Q. faginea, Q. ilex, Pinus pinaster in the most humid parts under marine influence and Tetraclinis articulata, Quercus ilex, Pinus halepensis on more continental situations. In many places, due to degradation by overgrazing, these forests are replaced by scrubs with the same species. Crops cover a large extent in this Ecological Zone.
In South Africa, the prevalent vegetation of this Ecological Zone is fynbos, which are sclerophyllous shrublands of 1 to 4 m high, with main shrub species Protea, Clifortia, Muraltia, Leucospermum, Resio, Erica and Serruria. Although the zone covers a small area, it is extremely rich in plant species of which many are endemic. The shrubs and bushes of fynbos vary greatly in height and density. They are mostly richly branched and have twisted boles. In typical fynbos true trees are virtually absent. The only tree species, silver tree (Leucadendron argenteum), is of limited distribution and is confined to the humid slopes of Table Mountain, at altitudes below 500 m. Large extents of cultivation and secondary shrublands with “rhenosterbos” (Elythropappus rhinocerotis) often have replaced the original fynbos.
Climate
In northern Africa, a wide and continuous transitional zone separates the previous Ecological Zone from the Sahara desert. Rainfall varies from 200 to 500 mm, with a long dry hot season of 6 to 11 months. Mean temperature of the coldest month is always more than 7°C.
Physiography
This transitional belt lies on the Marrakech and Agadir basins in Morocco and the lower inland plateaux in Algeria and Tunisia. Most of these areas are continental sediments of the upper Tertiary. Along the coast of Libya and Egypt, these sediments are partly overlain by Quaternary deposits.
Vegetation
Vegetation in this Ecological Zone is a tree pseudo-steppe with Acacia gummifera, Ziziphus lotus, Pistacia atlantica, often replaced, due to degradation, by pseudo-steppes with Artemisia herba-alba and Stipa tenacissima. In Morocco (Sous), the typical vegetation type is Argania forest.
Climate
In northern Africa, the landscape is dominated by the Atlas Mountains, which extend for over 3000 km from northern Morocco to Tunisia, parallel to the Mediterranean coast. Their altitude reaches 1500 m in Tunisia, 2500 m in Algeria, 4165 m in Morocco. The most septentrional range, the Rif Atlas, experiences a humid climate, due to proximity of the Atlantic Ocean: rainfall approaches 1000 mm, with a short summer drought tempered by a constantly high air humidity. More inland, the dry season is always pronounced and the climate becomes semi-arid to the south. Temperatures decrease with increasing altitude and 3 levels can be distinguished: submontane, montane and high elevation.
In South Africa, the largest highland area is the Highveld Region, which is more than 1000 m in altitude, bordered by the Drakensberg reaching more than 3000 m. Southward, in the Cape Region, the mountain ranges also belong to this Ecological Zone. In these mountains the climate is humid with a tropical regime, axeric in the extreme south (Outeniekwaberge). Rainfall varies from 500 to 1100 mm, with a short winter dry season, not more than 4 months. Winter temperatures are rather low, but more than 7°C up to 1500 m.
Physiography
In northern Africa, the Atlas mountains raised in the Tertiary, consist of several ranges: Rif Atlas in northern Morocco, becoming Tell Atlas in Algeria; High Atlas extending from the Atlantic coast and becoming Saharan Atlas in Algeria; Middle Atlas diverging from the High Atlas in Morocco; Anti-Atlas in southern Morocco, which is an elevated part of the African shield. The Atlas ranges extend in Tunisia as the Northern Tell, the High Tell and the Low Tell. Most of the rocks are Jurassic or Cretaceous sediments, often limestone, except in the Anti-Atlas.
In southern Africa, the Highveld is a part of the Great Interior Plateau of southern Africa. Its elevation gradually increases up to the southeast, from 1000-1200 m to 2000-3000 m in the Drakensberg. The latter is capped with basaltic lava flows, whereas the adjacent lower parts are overlain by Karoo sediments. In Cape region, most of the ranges are formed of sandstones.
Vegetation
In northern Africa, in the northern Atlas ranges, the lower slopes are covered by mixed forest with deciduous oaks or Quercus ilex associated with Pinus pinaster or P. halepensis; above 1600 m this forest gives way to Cedrus atlantica forest. In the southern drier ranges, a shrub pseudo-steppe with Juniperus phoenicea is replaced, in montane level, by Juniperus thurifera forest.
In southern Africa, Highveld region is covered with grassland, but an evergreen montane forest with Podocarpus, Apodytes, Halleria grows on the Drakensberg slopes. In the Cape region, a “temperate forest” with Podocarpus, Ocotea, Olea capensis grows on the slopes of the Outeniekwaberge, facing the sea. On drier places, a montane evergreen scrub with Erica replaces montane forest.
REFERENCES
Hamilton, A. 1989. African forests. In: H.Lieth & M.J.A. Werger (editors), Tropical rain forest ecosystems: biogeographical and ecological studies. Ecosystems of the world, 14b. Amsterdam, Elsevier, p. 155- 182.
LET. 2000. Ecofloristic zones and global ecological zoning of Africa, South America and Tropical Asia. Toulouse, France. Prepared for FAO-FRA2000 by M.F. Bellan. 199 pp + maps.
Walter, H. 1985. Vegetation of the Earth and Ecological Systems of the Geo-biosphere. Third, revised and enlarged edition. Berlin, Springer – Verlag, 318 pp.
White, F. 1983. The vegetation of Africa – A descriptive memoir to accompany the UNESCO/AETFAT/UNSO vegetation map of Africa. Series “Natural Resources Research” XX, Paris, UNESCO, 356 pp.
