1.1. Geographic position of the country
1.2. Socio-economic information
1.3. Ecological information
Ghana is almost centrally placed among the West African countries that lie along the shores of the Gulf of Guinea. It lies between latitudes 5° N and 11° N and between longitudes 1° E and 3° N, with the Port of Tema lying on the Greenwich Meridian. It is bounded on the West by Cote d'Ivoire, on the north by Burkina Faso, on the east by the Republic of Togo, and on the South by the Atlantic Ocean. Ghana covers an area of 23 million ha (239, 000 km2).
The rural population in 1997 was 63.1% of a total population of 18.3 million with an annual rate of change (1995-2000) of 2.3 % (FAO, 1999). The major employment sectors in Ghana are agriculture, services and industrial sectors. About 40 % of total income for all Ghanaians is derived from agriculture.
Fig. 1: Administrative region of Ghana
Per capita income was US $390 in 1995 with an annual growth rate of GDP (1990-1995) of 4.3% (FAO, 1999).
Ecological information on the northern regions of the country are provided by Kranjac- Berisavljevic' et al. (1999). The climate in this area (which extends from approximately 8° N, to lat. 11° N) is characterized generally as tropical continental, or savanna, with a single rainy season, from May to October, followed by a prolonged dry season.
The rainfall distribution and amount controls two distinct ecologies, which can be distinguished within the interior savanna environment of northern Ghana, namely the Guinea and the Sudan savanna.
Most of Northern Ghana falls within the Guinea Savanna Ecological Zone, which is associated with total annual rainfall of about 1000-1300 mm/annum. The rainy season is 140-190 days in duration, while the estimated reference evaporation (ETo Penman) is about 2000 mm/annum, creating a great seasonal deficit every dry season. The peak rainfall period is usually late August or early September. About 60% of the rainfall occurs within the three months (July to September), with torrential rains creating serious drainage problems. In most cases, absorptive capacity of the soil cannot withstand the intensity of the rain, thus creating high amounts of runoff, with erosion being one of the most significant agricultural constraints in the area. Precipitation, however, considerably outstrips evapotranspiration during the main period of the growing season (July-October).
The vegetation cover typical of Northern Ghana consists of mixed formations of fire resistant trees and shrubs. Moving northwards, within the savanna region, there is at first densely wooded and vigorous grassland (Andropogon, spp.) with fire resistant shrubs, often referred to as woodland savanna. Further north, at the transition between the Guinea and Sudan savanna, woodland savanna gradually gives way to less wooded tree savanna. Still further, in an increasingly arid environment, grass savanna is formed, with trees and shrubs either absent or very sparse.