Vegetation is the general term given to all living plants of various categories i.e. the trees & grass that cover the earth’s surface and those that grow in water. Biologically, vegetation is known as Flora. There are four major types of vegetation in East Africa which include; Equatorial /tropical rainforest, Savannah vegetation (woodlands and grasslands), Swamp or mangrove vegetation and Semi-arid/desert vegetation.
Factors influencing vegetation distribution in East Africa
- Climate: tropical forests grow in areas that experience heavy and reliable rainfall of about 1500mm and above. They also thrive well where temperatures are high throughout the year e.g. Mabira and Budongo forests. The amount of rainfall reduces as one moves away from the tropical region and this has led to Savannah vegetation consisting of Savannah Woodland and Savannah Grass Land e.g. Miombo woodlands. Desert regions receive rainfall which is very low, hence shrub and dry bush are dominant e.g. in Karamoja and Turkana land.
- Altitude: Tropical rain forests, mangrove forests and savannah vegetation thrive well on the low altitude areas e.g. Masai Mara while montane forests, heath and moorland thrive well on high altitude areas e.g. in Kabale.
- Drainage: Areas with permanent and stagnant water have favoured swamp vegetation as well as mangrove forest e.g. at the East African Coast. Areas with no permanent drainage features such as lakes and rivers tend to be very dry and these have a dominance of semi-arid vegetation e.g. Karamoja. Areas that are well drained have a dominance of savannah and tropical rain forests e.g. along mountain slopes.
- Soils: Areas with deep and well drained fertile soils tend to favour tropical forest vegetation. Areas with moderately fertile soils favour the growth of Savannah grasslands whereas very infertile areas will favour semi-arid vegetation and at times do not favour vegetation at all e.g. Karamoja region. The water retention capacity of the soil (soil porosity) will also influence vegetation. High water retaining soils e.g. clay soils lead to occurrence of swamp or mangrove vegetation e.g. along the coastal belts.
- Biotic factors: some areas that are infested with pests tend to scare away settlement creating favourable conditions for the growth of dense vegetation or savannah wood lands e.g. Miombo Woodlands of central Tanzania. Areas without pests attract settlements and lead to savannah grass land. Areas that are infested with locusts tend to have scanty vegetation because these insects destroy the existing vegetation.
- Human activities: Large areas of forested land have been cleared for timber to create room for settlement and cultivation which has resulted into forested areas turning into savannah grasslands. Large areas of savannah vegetation have been turned into shrubs and wood lands because of activities like over grazing, bush burning, charcoal burning e.t.c. Some areas have been left without vegetation because of human practices like monoculture and shifting cultivation e.t.c leading to semi-desert and desert vegetation. In areas where man has engaged in afforestation and re-afforestation activities, he has led to luxuriant tropical rain forests.