The miombo woodland, the largest of the Flora Zambesiaca, is dominated by Brachystegia spp. and Julbinardia globiflora and also a host of other important species. The woodland type cuts across commercial farmland, communal and resettlement areas, as well as National Parks. From a conservation point of view, this woodland is not yet under threat due in part to its size and also because it lies in commercial areas where forest resources are minimally used and conservation awareness is probably high. In addition, land in this area is privately owned and therefore often improves management of forest resources. Tree populations occurring in most communal areas are, however, under varying degrees of threat. In densely populated areas like Seke communal lands for example, this woodland is now nonexistent having been decimated during land clearing for agriculture and possibly as a source of fuelwood for the neighboring urban settlements of Chitungwiza and Harare. The woodland has been replaced by the resilient acacias which have since established themselves in the exhausted soils. The miombo woodland occurs in the eastern highlands (above 1 500 meters a.s.l.), highveld (above 1 200 meters a.s.l.), middleveld (800 to 1 200 meters a.s.l) and only partially in lowveld (below 800 meters a.s.l.).
The most important species of these woodlands are Brachystegia spiciformis, Brachystegia boehmii, Julbinardia globiflora (mainly used for fuelwood), indigenous fruit trees species such as Uapaca kirkiana, Vangueria infausta, Strychnos cocculoides, Parinari curetillifolia, Sclerocarya birrea, Combretum spp., Pterocarpus angolensis, Afzelia quanzensis, Piliostigma thonningii and Kirkia acuminata. The other species are mostly used for general farm construction, fuelwood and for the emerging carving industry. The proposed areas for conservation of this woodland are in the western part of the country.
The mopane woodlands cover an estimated area of 101 500 hectares of which 18.5 percent is a pure stand of Colophospermum mopane (Timberlake and Kwesha, 1996). Colophospermum mopane is used for fuelwood, durable poles for general farm construction, mine props, parquet floors and the leaves are a valuable browse for livestock (see appendix 2). The species is also a host for a highly prized worm (Imbrasia belina), widely consumed in the country and now commercially sold in formal markets. The mopane woodlands are found in the highveld, middleveld and also the lowveld. This woodland type is not under threat, although some natural stands are already being actively conserved.
The teak forests are confined to the Kalahari sand soils in the central and western part of the country. The total area of this woodland is about 1.99 million hectares roughly divided into National Parks (568 000 ha), communal lands (634 000 ha), private land (343 400 ha) and the Forestry Commission having the remainder of 439 000 hectares. The most economically important species of this woodland are Baikiaea plurijuga, Guirbotia coleosperma and the ubiquitous Pterocarpus angolensis. All three species are commercially exploited for furniture and the carving industry. There are however other tree species such as Brachystegia spiciformis and Burkea africana that are often associated with this woodland. Other species of less economic importance are Entandophragma caudatum (furniture making and carving) and Schinziophyton rautanenii (syn. Ricinodendron rautanenii) prized for its oil. A greater part of this woodland is in private land, Forestry Commission land and National Parks and therefore is under sound scientific conservation and management. Within these demarcated forests are included what is termed Strict Natural Reserves (more than a 100 hectares each). These areas are strictly for conservation with no exploitation permitted (Kwesha and Mkosana, 1994; Timberlake and Kwesha, 1996). There are a total of 11 Strict Natural Reserves made up of Pterocarpus angolensis (3), Baikiaea plurijuga (3), Guibortia coleosperma (1), Entandophragma caudatum (2) and Colophospermum mopane (2). The total area of demarcated forest is about 838 800 hectares made up of 24 forests ranging in size from 567 to 144 230 hectares. Although this woodland sits on one of the most fragile environments (soils are highly erodible) in Zimbabwe, it probably represents the best forest conservation and management. The woodland is managed for its commercial timber, wildlife, cattle grazing and water catchments. Where the woodland has been degraded, other species such as Burkea africana and Terminalia spp. have emerged.
The Acacia woodland is dominated by Acacia species which include A. karroo, A. nilotica, A. albida (syn. Faidherbia albida), A. nigrescens, A. erioloba and A. tortilis on various soil types. These species are common in Zimbabwe from as low as 400 meters above sea level to the highveld where elevation is over 1 600 meters a.s.l. They occur in river valleys, abandoned fields, degraded areas and also in association with other important non-acacia species such as Sclerocarya birrea and Combretum spp.
Several acacias have of late been the subject of intense studies in Zimbabwe. These studies have focused on their taxonomy, biology as well as gum arabic production, nitrogen fixation, browse and fodder value and for restoring degraded sites. Comprehensive provenance-progeny trials have been established in Zimbabwe to evaluate adaptation, browse and fodder value of pods and production of gum arabic. The species included in these studies are A. karroo, A. nilotica, A. albida, A. senegal, A. erioloba and A. tortilis. There is no deliberate conservation work on these species in Zimbabwe but many trials established with provenances from the species' natural range are likely to be kept for ex situ field gene banks.
The Terminalia/Combretum woodlands are dominated by Terminalia spp. and Combretum spp. These species are also associated with other important species such as Sclerocarya birrea, Strychnos cocculoides, Saccharopolyspora spinosa), Piliostigma thonningii, etc. Terminalia serisea and Combretum spp. are mostly used for poles, tool handles and firewood. They do not have a commercial value per se. There is no deliberate conservation work on these species in Zimbabwe.
The Afromontane region is often divided into vegetation types by elevation. The four vegetation types recognized by altitude are the high altitude (above 1 800 meters), high to medium altitude (1 400 to 1 800 meters), medium altitude (1 000 to 1 400 meters) and low altitude (below 1 000 meters) (Timberlake, 1994). The major species of importance are Syzygium spp., Widdringtonia nodiflora, Albizia spp., Trichilia dregeana, Lovoa swynnertonii and Khaya nyasica. Some of the most endangered species, like Bivinia jalbertii, Milia excelsa (syn. Chlorophora excelsa), Strychnos mitis and Warbugia salutaris, also occur in the lower altitudes of the Afromontane. Another moist forest, Chinyaduma, is reported to be under intense pressure from land clearing and human settlements.
The Afromontane forests are increasingly coming under intense pressure from human settlements and may be threatened by some of the introduced exotics that have become invasive. The Chirinda, Haroni and Rusitu forests, with a combined hectarage of less than 2 000 hectares, are said to be the only remaining moist forests in Zimbabwe. Timberlake (1994) presented evidence showing that these forests have not changed significantly in size since 1949.
There is however some speculation that, unless control measures are instituted, the remnant natural Afromontane vegetation may be threatened by industrial exotic species that are becoming invasive. Currently, there are probably two species, namely Pinus patula (from Mexico) and Acacia mearnsii (from Australia) that can be considered serious weeds of the natural forests of the eastern highlands of Zimbabwe.
The rate of deforestation has been estimated at between 70 000 to 100 000 hectares of land cleared annually (Gondo and Mkwanda, 1991; Moyo et al., 1991). This clearing of land is mostly for agricultural purposes.
