2.1. Phytogeography of the country
2.2. Utilization patterns of forest species
2.3. Threats
Ghana's total forest zone is estimated at 81,342 km2 out of which about 17,845 km2 are known to be under reservations. The savanna woodland zone, located to the northern portion of the country occupies about 65.5% of the country's total land area. Only about 15% of the savanna woodland is under some form of forest reservation.
The following description of the vegetation types of the open broadleaved forest of the country could be given according to FAO/UNEP (1981):
The Guinea savanna woodland
It's extends over the area north of the closed forest and reaches the southeast of the country. This woodland is typically composed of short statured trees, usually not forming a closed canopy and often very widely spaced. Most of the areas lie within the "one-peak" rainfall zone. The true Guinea savanna woodland is a climatic climax. Though this is the case in the centre and north of this zone, there is a very large area in the south where this type of savanna woodland is considered to be a "derived savanna" brought about by human interference. Periodic grass fire-in many localities these are annual- sweep across the country during January to April. Many of the trees are fire resistant and have thick bark.
Riverain woodland
This vegetation type established along the rivers in the northern area contains Anogeissus schimperi, Celtis integrifolia, Cola laurifolia, Cynometra vogelii, Lannea spp. and Parinari polyandra. Throughout the Guinea savanna woodland are Anogeissus schiemperi, Vitellaria paradoxa, Detarium senegalense and Parkia filicoidea. Daniellia oliveri is common in the South, and particularly so in the derived woodland savanna, where it is often associated with Entada sudanica. The Acacia species are more frequent in the north than in the south. Combretum spp. and Terminalia spp. are numerous and often indicate areas of poor drainage. The savanna mahogany, Khaya senegalensis is riparian. On worked out land, the vegetation consists of short shrub growth of Bauhinia rufescens, Combretum spp. and Piliostigma thonningii. Fires and grazing tend to restrict their height growth.
The Sudan savanna woodland
It is restricted to a small area in the extreme northeast of the country. It has the highest density of rural population, which has resulted in settled farming. This zone has very sparse tree cover. The arable land contains a sprinkling of Vitellaria paradoxa, Parkia filicoidea, and Tamarindus indica, all of which provide an extra source of food for the local population.
The main value of savanna forest is the supply of firewood, timber and grazing and non-wood products such as thatch, fruits etc. For trees on farmlands, the farmer usually has the right to fruits. Vitellaria paradoxa and Parkia sp. are cash sources. Women exclusively process the fruits. They are rarely planted. Young natural regenerated seedlings are protected during weeding.
The savanna zone is poor in indigenous timber resources for industrial use, and only a few species in this zone are of any commercial interest.
The area of unreserved forests is estimated at 63,446.77 km² occurring is small patches and therefore making it uneconomic to manage. A substantial volume of industrial raw materials in the form mostly of timber, however, comes from the unreserved forest areas to augment timber output from the forest reserves. Over 360 tree species have been recorded of which about 190 grow to timber size.
The economic value of Ghana's forest resources lies in the revenues derived mainly from exploitation of its wealth of commercial timbers and the considerable volume of commercial woods and other non-timber forest products (NTFPs). Ghana's forestry sector contributes 6% of Ghana's energy requirements derive from its forest resources. This is because the majority of rural dwellers burn wood fuel for cooking.
The total conserved area is about 15 million hectares. It is estimated that 20,000 hectares per annum of the reserved area is lost to agriculture, or through bush fires and other human activities. In densely populated communities, the populace encroach the reserves to graze animals or obtain dead wood and fruits. Mining for minerals is threatening one of the reserves near Bolgatanga in the Upper East Region.
Agriculture impact on forest lands
As in most parts of Sub Saharan Africa, farming systems in the Northern Ghana are complex and often quite sophisticated systems of production, which have adjusted to external factors (Kranjac-Berisavljevic' et al., 1999). According to these authors, the region of northern Ghana has two principal farm types: compound farms and bush farms. The farming systems prevalent in the region are mixed cropping, mixed farming, inter-cropping and mono-cropping. The crops cultivated in the compound farms include cereals (maize and sorghum), tobacco, yam and vegetable whereas those cultivated in bush farms include cowpea, groundnuts, bambara groundnuts, maize, sorghum, millet, yam and cassava. Cotton is cultivated as a cash crop.
The bush farms are based on the bush fallow system in which cropping and fallow periods are alternated. The fallow periods have been drastically reduced to between two and four years (Kranjac-Berisavljevic' et al., 1999). According to Dwumfour (1994), increased demand for agriculture products and industrial raw materials, from rapid human population growth, has caused the fallowing period to be reduced. Recently with declining soil fertility of agricultural lands, pressure of demand for virgin lands for cocoa, oil palm and other cash crops, encroachment has been a scare to the forester, ecologist or environmentalist. This is only a local problem. These problems threaten the conservation of forest genetic resources (Peprah, 1999).
Forest exploitation (timber and non timber products)
Charcoal and firewood are major income earners for members of communities. Those who cut the trees and shrubs do not consider replacing them. This leads to environmental degradation and loss of genetic resources. Economic trees, shrubs and grasses continue to go up in flames every year due to bushfires. If the present trend continues unchecked, most parts of Northern Ghana will easily become desert.
For centuries, forest product gathering, which is for a subsistence society, has been a major form of land use. This has become significantly commercialised since demand for these items has risen sharply with the increase in population and growing scarcity of produce. Therefore, Ghana experiences levels of resources utilization that far exceeds the productive capacities of the exploited species to sustain exploitation. A number of mushroom species and African snail, Anachna sp., which used to constitute a major protein source in the past, have become increasingly scarce. Rattan and cane species (Calamus deerratus, Raphia hooker, Ancistrophyllum secondiflorum, Ancistrophyllum opacum and Eremospatha spp.) used in the rattan/cane craft are becoming rare (Dwumfour, 1994).
Other types of threats
Bush fires pose serious threats to the environment and forest genetic resources conservation. Ghana experienced over 40 fires in the closed forest areas during the dry years of 1982/83.
Assessment by FAO indicated that about 50% of Ghana's vegetation cover fell victim to the bush fires. 35% of standing crops (cocoa, oil palm etc.) and cereals (sorghum, millet, maize) were also destroyed in the same year (Dwumfour, 1994). Since then bush fires have become frequent, consequently forests bordering the savannah have been seriously degraded.
