There are extensive areas in Africa where few people live and where natural vegetation and wild animals have not been disrupted by such activities as farming or the raising of livestock. In some parts of the continent large forest preserves have been established.
Most of Africa's forests are tropical rain forests, or selvas. They cover less than a tenth of the continent and occur where rainfall is heavy throughout most of the year. Such a forest is made up of several layers of vegetation. The top layer consists of the crowns of trees rising 125 to 250 feet (38 to 76 m) in height; the lower layers are made up of the tops of shorter trees, shrubs, and vines. Most of the trees are broad-leaved evergreens, though some are conifers. They yield pulp, timber, and such cabinet woods as mahogany, ebony, and teak. Oil palms, rubber-producing trees and vines, orchids, and lilies are among the numerous kinds of plants found in these forests.
Savannas, which cover probably a third of the continent, consist of areas where the ground cover is mainly grass. They are, however, dotted by woodlands, scattered trees, or shrubs, depending on the length of the dry season. Those bordering the tropical rain forests have coarse grasses up to 12 feet (3.7 m) high and large woodlands of deciduous trees. Trees of these savannas also include many evergreens found in tropical rain forests, such as oil palms, rubber trees, and African ebony trees. There are also shea trees (whose seeds yield an edible fat), baobabs, flat-topped acacias, kapok, and many trees that bear edible fruit.
Where the dry season becomes more pronounced, grass is shorter than in the more humid savannas; seldom is it more than five feet (1.5 m) high. Palms, baobabs, acacias, and such brightly flowering trees as cassias and erythrinas grow in small clumps or are scattered singly over the grassy areas.
Bordering the savannas in areas of increased aridity and longer dry seasons are the tropical steppes. These are regions where short grasses prevail and trees are scarce. Among the trees found here are thorny acacias, euphorbias, dwarf palms, and jujube trees. In steppes bordering on deserts—often called subdesert steppes—there are almost no trees, and the grasses grow in widely scattered bunches. After rains a thin carpet of various grasses and flowering plants springs up and thrives for several weeks.
True deserts, such as the Sahara and the Namib, have virtually no vegetation except at oases (places watered by springs or wells). Vegetation at oases includes date palms, fig trees, willows, poplars, and tamarisks.
vegetation occurs along parts of the northern and southern coasts. It consists of many kinds of shrubs and small trees, both deciduous and evergreen. Many of the plants have waxy, leathery leaves and long taproots, which enable them to withstand long, dry summers. Some are scrubby and thorny, especially the deciduous varieties. Characteristic in the north are cork oak, olive trees, cedars, and pines; in the south, laurels, cedars, and ironwood. Grasses and low flowering plants grow only during the rainy months.
In some parts of Africa, vegetation reflects highly localized conditions. Probably the most varied is the montane vegetation of highlands, particularly in Ethiopia and the mountains of the Great Rift Valley. The kind of vegetation that grows there depends on elevation, latitude, and direction of the winds.
Often the slopes are mantled by luxuriant forests, which are predominantly evergreen. Montane forests yield valuable timber and cabinet woods. Bamboo and wild varieties of coffee and banana also grow here. Giant lobelias and tree-groundsels characterize some of the montane forests of eastern Africa. At higher elevations, grasses and colorful, low-growing plants are typical. The High Veld of southern Africa is a temperate grassland between 3,500 and 11,000 feet (1,070 and 3,350 m) above sea level.
Mangrove forests occur along many parts of the African coast, but are most extensive along the Gulf of Guinea. These contain, in addition to mangrove, a variety of other trees adapted to life in muddy estuaries and tidal flats. Relatively large areas of swamp and marsh also occur along the larger rivers and lakes of western and central Africa. Papyrus, tall grasses, and lotus are the most common plants. The Sudd region of the White Nile River is one of the largest marshes in the world.