3. The Forest and Trees Resources of East and Southern Africa

The SADC region covers a wide and diverse geographic environment, from sandy treeless and sometimes shrub-land desert to tropical dense forests. The rainfall ranges from as low as 20 mm per annum in the desert of Namibia to over 2000 mm per annum in the tropical forests of Tanzania. The rainfall distribution for much of the greater part of southern Africa is mostly in summer with a distinct dry season. In some parts of the region, rainfall is received in winter (Western Cape of South Africa) and may also be received through out the year in some mountain areas. Lesotho, a mountainous country lying between 1 500 m and 3 350 m a.s.l. and Mauritius, an Indian ocean island have natural vegetation which is very distinct from other countries.

The natural and exotic plantation forests cover an area of 152 195 000 ha which is 27.4% of the total land area. The natural forests cover 98.5% of the total forested area while the remainder of 1.5% is under exotic forest plantations (Table 2). Among individual countries, the natural forest cover ranges from as low as 0% of the total forest cover in Lesotho, where there is very little natural forest left to almost 100% in Botswana which does not have any exotic plantation forests.

Table 2: Extent of Forest Resources in the SADC countries

* Source: FAO (2001)

3.1 Exotic Forest Plantations

Exotic forest plantations were established at the turn of the 20^th century to supply timber, pulp and paper and tannin. Exotic forest plantations comprise mainly of Pinus, Eucalyptus, Acacia and Cupressus spp. The area covered by exotic forest plantations is 2.3 million hectares of which 1.5 million hectares, or 66.5% of the sub-region’s total forest plantation area is in South Africa (Table 2). Three countries namely Botswana, Lesotho and Namibia do not have any commercial plantations, except some small woodlots, which were established for the provision of fuelwood and poles for general farm construction.

3.2 Woodland or Vegetation types of the SADC

The SADC region has a variety of natural forests or woodlands whose extent is chiefly influenced by the amount of annual precipitation, which is mostly in the form of rain. In areas where rainfall is high and received throughout the year, tropical and subtropical moist forests are found. These are mainly small in extent compared to the more widespread woodlands that are found in the drier areas. The largest tropical forest area is in Tanzania with an estimated area of 1.3 million ha which is about 3.4% of the natural forest. The greater part of the SADC region is covered by the Miombo ecoregion, which has several vegetation types (WWF 2002). This ecoregion, which is dominated by tree species that belong to the Caesalpinioideae sub-family, covers approximately 3.6 million square kilometres and spans across Botswana, Malawi, Mozambique, Namibia, South Africa, Tanzania, Zambia and Zimbabwe. This woodland also extends into Angola and the DRC. The recognised woodland types of this Miombo ecoregion are the Wet and Dry Miombo, Mopane, Baikaiea, Acacia/Combtretum, Burkea/Terminalia/Combretum, Afromontane, Cryptosepalum and Itigi thicket (WWF, 2002).

The Wet Miombo (rainfall +1000 mm per annum) is found in Tanzania, north-central Mozambique, northern Malawi and Zambia (Fig. 2). This woodland is also found in Angola and the DRC. The Wet Miombo woodland is a floristically rich woodland, with dominant tree species such as Brachystegia floribunda, B. graberrima, B. taxifolia, B. wangerrmeana and Marquesia macroura. The dominant tree species in the floristically poorer Dry Miombo woodland (rainfall -1000 mm) are Brachystegia spiciformis, B. boehmii and Julbernadia globiflora. Some Acacia spp. are often found in association with this woodland type, particularly along drainage lines. The Wet and Dry miombo woodlands respectively cover an area of 1 358 175 km² and 1 214 533 km². Table 3 shows the distribution by country of the wet and dry miombo woodlands.

Table 3: Distribution and area (km²) of the wet and dry miombo woodland in the SADC countries*

* (WWF, 2002)

The Mopane woodland, which is largely species poor, extends from the provinces of Inhambane and Tete in Mozambique, through Zimbabwe, Zambia, Botswana, Namibia and South Africa (Fig. 2). The Mopane woodlands cover (including Angola) an estimated 384 037 km². Colophospermum mopane is the predominant species, occasionally occurring together with Acacia spp., Adansonia digitata and Sclerocarya birrea.

The Zambezi teak woodlands, which are confined to the Kalahari sand soils are found in Western Zambia, north eastern Namibia, western Zimbabwe and eastern Botswana (Fig. 2). The most economically important timber species of this woodland are Baikiaea plurijuga, the ubiquitous Pterocarpus angolensis and to a limited extent, Guibourtia coleosperma. Other species of less economic importance are E. caudatum (furniture making and carving) and Schinziophyton rautanenii (syn. Ricinodendron rautanenii) prized for its oil in Namibia. The Baikiaea woodland covers an area of approximately 260 171km² including Angola.

The Acacia and Combretum woodland, as the name implies is dominated by both Acacia and Combretum species. This woodland covers an area of 103 887 km². The other associated tree species are S. birrea, Terminalia spp., Lochocarpus capassa, A. digitata and sometimes mopane. The Burkea-Terminalia woodland is often described as an impoverished woodland type. This woodland only covers an area of approximately 96 162 km² (Fig. 2)

Fig. 2: The Miombo-ecoregion and its woodland types

Two more forest types found in the Miombo ecoregion is the dry evergreen forest or the Cryptosepalum that is only found in Zambia and the Itigi forest found in both Zambia and Tanzania. The Cryptosepalum woodland which stretches for 37 908 km² occurs on the Kalahari sands in western Zambia. The dominant species is Cryptosepalum pseudotaxus. The Itigi woodland is a dry deciduous forest that covers an estimated 15 405 km². The dominant tree species are Baphia spp., Combretum spp. and Bussea massaiensis.

The Afromontane and Mangrove forests are also significant in the SADC region. The Afromontane consists of mosaic of moist evergreen forest and grasslands. The Afromontane forests cover approximately 98 685 km². Mangrove forests are found along the coast in Mozambique and Tanzania. The largest mangrove forest is in Mozambique, with an area of 396 000 ha and Tanzania has about 116 028 ha.

3.3 Deforestation

It is estimated that the average deforestation rate (rate of loss of forest cover) in the SADC region is about 0.6% per annum. This rate of loss of forest cover ranges from 1.2% in Swaziland to -2.4% in Malawi. Deforestation is highest in Zambia and Malawi where it is estimated at -2.4% (Table 2). According to FAO (2001), Swaziland is the only country among the 11, which has reported a positive improvement in forest cover of 1.2% over the last ten years. Deforestation in the SADC countries is mainly from conversion of forestland to agriculture, a high dependence on wood as an energy source and uncontrolled frequent, but very late fires. In Malawi, for example, the main causes of deforestation are cited as high population growth rate in relation to available land, poverty, market and policy failures, drought, uncontrolled tree felling for fuelwood to cure tobacco in both the small and large scale farming sectors, opening up of new gardens and farming areas, firewood for commercial purposes, overstocking and infra-structural development (Minde, et al., 2001).

In Zimbabwe for example, more than 70 000 hectares of forested land are believed to be lost to agriculture every year. In Tanzania, the loss in forest cover ranges between 130 000 and 500 000 ha annually while Zambia is losing between 200 000 and 300 000 ha per annum and Malawi has an annual average deforestation rate of 48 000 ha. There is however, a paucity of information on the rate of deforestation by individual woodland types as deforestation rates are general on a national scale. In the year 2000, a total of 186 000 hectares of woodland were destroyed by fire in the SADC countries (FAO, 2000).