3.1. In situ conservation activities
3.2. Ex situ conservation activities
3.3. Selection and genetic improvement
3.4. National priority species
Protected areas
The forest reserves have been places where most species can be found, particularly medicinal plant species. Within the high forest zone, this is considered to be more than the minimum requirements for the purposes of environmental protection. The reserved forest is made up of 11, 590 km² of production forests, 4,323 km² of protection forests and about 1,980 km² of game production reserves. Table 1 shows the distribution of reserve areas within the three upper region of the country.
Table 1. Distribution of reserve in the dry region of Ghana
|
|
Upper East Region |
Upper West Region |
Northern Region |
Total |
|
Total land area (km²) |
8,8421 |
- |
70,384 |
- |
|
Reserve area (km²) |
1,536 |
1,295 |
3,557 |
6,388 |
|
Plantation area (km²) |
20 |
- |
- |
- |
Arboreta
In Ghana there are arboreta at three forest reserves namely, Subri Forest Reserve (Moist evergreen), Pra-Anum Forest Reserve (Moist semi-deciduous) and Bobiri Forest Reserve (Moist Semi-deciduous) (Peprah, 1999). According to the author, the construction of a road through the Subri forest reserve has partly destroyed the arboretum. Fire in 1983 destroyed the arboretum at Pra-Anum Forest Reserve but it has fully regenerated. Presently, the most functional arboretum is the one at Bobiri Forest Reserve. There are about 102 species found in this arboretum.
Sacred forests
Sacred groves are believed to be the habitats for the gods and ancestors of the local communities. As such, these groves are believed to provide protection for the people. The groves are protected, conserved and maintained through a mechanism of beliefs, taboos, prohibitions and restrictions. Burning, cutting of grass and fuelwood are prohibited in these areas.
The conservation of sacred groves by traditional beliefs has led to the preservation of numerous tree and shrub species in the numerous sacred groves scattered over the country.
Traditional agroforestry parklands
In Northern Ghana, farmers maintain and manage different tree species on croplands. The species usually maintained include Parkia biglobosa, Faidherbia albida and sheanut (Vitellaria paradoxa Gaerntan) (Kranjac-Berisavljevic' et al.1999). According to these authors, intercropping on arable lands of sheanut and dawadawa (Parkia filicoides) is common in all regions of Northern Ghana. These two tree species are generally not cut and are used as a regular source of fuelwood or other timber products; they therefore form the common species on farmland and fallow land. Almost all farmers in the community selectively preserve them.
Fig.2: Map showing few National parks of Ghana
Seed banks
In Ghana storage of seeds as means of conserving forest genetic resources is not a common practice. A small cold room was built under the Silviculture Branch of the Forestry Department (Forest Services Division) in 1971 but it broke down after 3 years and has since not been rehabilitated. Deep freezers have been used thereafter but they cannot provide the optimum conditions necessary for prolonged storage (Peprah, 1994).
Currently there are no forest tree seeds under storage but plans are well ahead to build a National Seed Centre with cold rooms where at least the orthodox species could be stored as a mean of conservation.
In Ghana the present demand for forest tree seed is estimated at 10,000 kg per annum. Projected demand is even higher because of the intensification of afforestation, reforestation, agroforestry and community forestry programmes.
Currently, some institutions and organisations such as the Forestry Service Division (formerly Forestry Department) and the Agroforestry Unit do their own seed collection from the natural forest reserves and existing plantations. Others depend on the Forestry Research Institute of Ghana (FORIG) for their seed supply. Request to FORIG for seeds keep increasing year by year from both local and foreign users, but the problem is that FORIG cannot meet the demand. This is because FORIG has not got the facilities to collect and store seeds on a large scale (Peprah, 1994).
Enrichment planting
The aim of enrichment planting is to increase the stock of valuable species. It is in effect an artificial regeneration method being used to supplement natural regeneration.
Enrichment planting plots were established in the Asenanyo (Moist Semi-deciduous), Bia Tano (Moist Semi-deciduous), Nueng Forest Reserves (Moist Evergreen) between 1975 and 1978 (Peprah, 1999). The plantings were done to increase the stock of the heavily exploited or to increase the economic potential of the species in the forest reserves. Pericopsis elata, Entandrophragma utile, Entandrophragma angolense, Entandrophragma cylindricum, Khaya anthotheca, Khaya invorensis, Nauclea diderrichii, Terminalia ivorensis and Triplochiton scleroxylon were the species planted.
With a wide array of species that are economically important and widely used, it might be expected that a sufficient diversity of tree improvement programmes will be generated. However, this is not so because of financial difficulties which had affected the Forestry Research Institute of Ghana in the mid 1970's and brought most of the field trials to a virtual standstill.
Several years have been spent collecting important germplasm and their consequent establishment in field trials. There is therefore need to build on this resource. Some of the provenance trials have reached their half rotation and others have passed, again almost all the seed orchards are flowering and fruiting regularly.
Provenance trials
In Ghana a number of provenance trials have been established with the aim of conserving gene pool, providing information on the nature and extent of genetic variation within and between provenances throughout the species native ranges and providing a basis for selection of species for afforestation (Gyimah, 1994 cited by Peprah, 1999). The following species were concerned by these provenances trials (Peprah, 1999): Terminalia ivorensis (10 provenances), Pericopsis elata (12 provenances) and Triplochiton scleroxylon (7 provenances), Tectona grandis (13 provenances), Gmelina arborea (11 provenances), Cordia alliodora.
Clonal trials
Vegetative propagation techniques that would have allowed the establishment of clonal trials to identify the extent of genotypic variation in any of the species mentioned above were not fully utilized (Peprah, 1999). The only exception is Triplochiton scleroxylon, where a trial was planted at Afram Headwaters Research Centre in 1963 to compare the performance of rooted cuttings with stumps and striplings. The results showed that up to 12 years old there were no differences between these different types of planting stock. It needs emphasizing, though, that the cuttings were of unselected clones. This experiment has been destroyed completely by fire. Similar experiment with rooted cuttings of Pinus caribaea were compared with seedlings. The results also showed that there was no significant difference between the two types of plants. According to Leakey (1991), this indicates that cuttings are in no way inferior to seedlings. Therefore great benefits of clonal selection could be utilized to maximise genetic gains in yield and other parameters.
Clonal testing on teak is presently going on. Open pollinated seedlings are being used. The materials are from the clonal seed orchards of teak. The clonal seed orchard of teak is also being managed. Half of the plot established in 1978 has been top pruned since 1997.
Vegetative propagation by stem cuttings is being used to propagate some indigenous species to determine their potential capability in rooting if the need be. Species being tried are Terminalia spp., Khaya ivorensis, Ceiba pentandra, Entandrophragma angolense, Triplochiton scleroxylon and Milicia sp.
Forestry in Ghana has not yet taken advantage of biotechnology methods in afforestation. This is due to lack of facilities and personnel. Presently, interest has been on the use of tissue culture plantlets in plantations, for species, which fruit irregularly, like Triplochiton scleroxylon. A biotechnology laboratory is being built at FORIG to facilitate progress in afforestation programmes with some indigenous species.
Genetic resistance in Milicia species
This is an important component of International Tropical Timber Organisation (ITTO) project, which involves an examination of genetic resistance in Milicia spp. to the very serious attacks of the psylid Phytolyma lata. This insect prevents the establishment of plantations to produce the timber (Iroko or Odum) of these important tree species. It has been thought that mature shoots are tolerant or less susceptible to attack and some trees may be more resistant than others. The project has quantified both these possible sources of resistance. The susceptible and resistant trees have been cloned using stem cuttings and replicates tested for their susceptibility. Results have indicated that resistant clones are less frequently attacked and that insects in any galls formed do not develop to maturity.
List of priority species found in the savanna region of Ghana:
Vitellaria paradoxa (Shea)
Anogeissus leiocarpus
Azadirachta indica
Parkia biglobosa (dawadawa)
Adansonia digitata (Baobab)
Ceiba pentandra
Tamarindus indica
Diospyros mespiliformis
Senna siamea
Khaya senegalensis
Albizzia lebbeck
Faidherbia albida
Acacia nilotica
Acacia seyal
Acacia sieberiana
Acacia polyacantha
Combretum molle
Detarium senegalense
Terminalia glauscescens
Afzelia africana
Lannea acida
Mitragyna inermis
