2.1. LOCATION
2.2. CLIMATE
2.3. SOILS
2.4. VEGETATION
The Republic of Botswana is roughly situated in the centre of Southern Africa. It is bounded to the north by the Caprivi Strip in Namibia, to the north east by Zimbabwe, to the south-east and south by the Republic of South Africa and to the west by Namibia. Botswana has a total land area of approximately 581 730 km2 (IUCN, 1992).
The average annual rainfall of Botswana varies from a maximum of about 650 mm in the northern part of the country to a minimum of just under 250 mm in the extreme south-west in the Kgalagadi (Otsyina and Walker, 1990). Over 90 per cent of the rainfalls in the summer months between November and April and as such there is high evaporation. Rainfall is irregular and there is considerable variation in actual rainfall from year to year. Temperatures in summer can go above 35°C while winter temperatures can drop to 0°C and below with occasional frost at night in the months of June to August.
Soils are generally infertile and derived from acid igneous rocks and about 70 per cent of the country are covered by the Kalahari sands. The sands vary in depth from less than 3 meters to occasionally over 100 meters deep (sand veld). In some areas, the sands are underlain by calcrete of varying thickness. In the eastern side of the country, the soils are characterised by sandy and loamy sand soils (hard veld) (Ntogwa, 1995).
Forest type vegetation is confined to the miombo woodlands in the Chobe area in the north, the wetland and alluvial forests in and around the Okavango and the Linyanti swamps and a number of relatively small areas of Colophospermum mopane (mopane) belt where a high density occurs. Approximately 4 million hectares of Botswana land surface can be characterised as forests and about 455 000 hectares are gazetted forest reserves. Most parts of the country however have a savanna type vegetation. The largest savanna type vegetation is called the sand veld and covers approximately 65 percent of the country and occurs mainly in areas that receive an average rainfall of 400 mm. The sand veld is dominated by Acacia erioloba (camel thorn), Acacia luederitzii (bastard umbrella thorn), Acacia tortilis (umbrella thorn) and Dichrostachys cineria (sickle bush) (Ntogwa, 1995).
The vegetation found in the more densely populated areas of eastern Botswana falls into the hard veld vegetation group which is characterised by Combretum apiculatum (red bushwillow), Terminalia sericea (silver terminalia), Colophospermum mopane and Acacia species. Riparian woodlands are found along most of the major river courses. The largest riparian woodland formation occurs along the lower reaches of the Limpopo and Shashe rivers. The dominant tree species in these areas include Combretum erythrophyllum (river bushwillow) and Ziziphus mucronata (buffalo thorn).
