Contents - Previous - Next

This is the old United Nations University website. Visit the new site at

Pilot study of production pressure and environmental change in the forest-savanna zone of southern Ghana

5: Background and objectives of the study of production pressure and environmental change in the southern forest-savanna transition zone
6: A multidisciplinary integrated methodology
7: Land use and cover patterns
8: Soils
9: Floral and faunal diversity
10: Population growth and urban demand
11: Ability of the farming systems to cope and strategies for sustaining farming
12: Gender and non-governmental organizations in environmental management

5: Background and objectives of the study of production pressure and environmental change in the southern forest-savanna transition zone

The forest-savanna zone

Edwin A. Gyasi

The study of production pressure and environmental change in the forest-savanna zone of southern Ghana originated in 1993. It followed the formation of the nucleus of an envisaged West Africa component, chapter or cluster of the United Nations University (UNU) Project of Collaborative Research on Population (now People), Land Management and Environmental Change (PLEC). Made up of seven academics drawn from the University of Ghana, the nuclear group was constituted shortly after a meeting that Professor Brookfield, PLEC scientific coordinator, and Dr. Uitto, PLEC administrative coordinator, had with potential members of the envisaged duster, during a UNU conference on the Sub-Saharan environment at Accra in March 1993.

Subsequently, a pilot study proposal focused on environmental change in three sites centred on Yensiso, Amanase and Sekesua in the southern sector of the forestsavanna ecotone was formulated and carried out in a multidisciplinary manner by the PLEC interdisciplinary team of natural and social scientists between August 1993 and January 1994 under the auspices of the UNU.

The biophysical environment embodies the basic human life-support systems and is the habitat of humanity. It has always been characterised by change. The change is accelerating universally, with fundamental implications for sustainable human livelihood (Turner et al. 1990). However, its causes and qualitative character remain inadequately understood.

In Ghana, there is evidence of accelerated environmental change. The change is most noticeable in the soils, flora and fauna, which appear to be increasingly endangered in all the major agroecological zones, including the mosaic of forestsavanna (Benneh and Agyepong 1990) (fig. 5.1).

Figure 5.1 The Study Area and Major Agroecological Zones in Ghana


The basic terms of reference for the study, focused on the southern forest-savanna zone, required us to examine, within five months, the character of environmental endangerment in terms of natural vegetative cover and soil fertility loss, fallow length reduction, biodiversity including agrodiversity erosion, other indicators of the general lowering of the intrinsic quality of the land, and the expansion of the forest-savanna vegetation. In particular, the study was required to focus on population density, migration, gender issues in environmental management, farming systems including technology and land tenure, and other variables thought to play an important role in environmental transformation, and try to:

Subsequently, we interpreted the terms of reference as a mandate to investigate changes in the biophysical environment of the forest-savanna ecotone, with special reference to those aspects that threaten or endanger the soils, biodiversity, agriculture and the capacity of the environment to support life.


On the basis of the ideas of various writers, and of our own intuition, we, a priori, associated the apparent environmental changes, most especially the negative ones, principally with the stress generated by production pressure related to:

Other hypotheses associated the changes with inadequate policy and the fragile character of the tropical forest ecosystem (Boserup 1965; Gyasi 1976; Ehrlich et al. 1977; Blaikie and Brookfield 1987; Benneh and Agyepong 1990; Environmental Protection Council 1991; Brookfield 1993a, 1993b; Amanor 1994). Therefore, in our view, the basic research task boiled down to determining the empirical veracity of these hypotheses within the context of the forest-savanna zone.

The forest-savanna zone

Ghana's forest-savanna zone lies in the area transitional between humid forest and dry savanna (fig. 5.1). The approximately 6,200 km2 southern is the study area. It is characterised by 1,260 mm mean annual bimodal rainfall, generally adequate to support two crops, and by a prevalence of ochrosols which, like most of the other fairly varied soils, are suitable both for perennial tree crops and annual food crops (Soil Research Institute 1971; Dickson and Benneh 1988). Within it, however, the population, presently estimated at about 1 million, is increasing as is the land usage, and a mosaic of forest-savanna vegetation is expanding at the expense of the thick deciduous forest that predominated in the past.

The southern sector of the forest-savanna transition zone has considerable diversity in farming systems, land-holding arrangements and crops. This relatively high agrodiversity reflects the transitional character of the ecosystems, permitting use of crops adapted both to humid and drier conditions, and to the ethnic and associated cultural diversity, strongly affected by migration (Hill 1963). The zone is a major producer of food crops, notably cassava (manioc), maize (corn) and vegetables for the nearby coastal urban areas and other settlements in Ghana, a country whose population is still growing at an annual rate of three per cent, with far-reaching implications for the biophysical environment (Dickson and Benneh 1988).


1. Edwin A. Gyasi (leader/coordinator); Gotfried T. Agyepong; Kojo Sebastian Amanor; Elizabeth Ardayfio-Schandorf; Lewis Enu-Kwesi; John S. Nabila; Emmanuel Owusu-Bennoah.


Amanor, K.S. 1994. Ecological knowledge and the regional economy: environmental management in the Asesewa district of Ghana. Development and Change 25(1): 4167.

Benneh, G. and Agyepong, G.T. 1990. Land Degradation in Ghana. London: Commonwealth Secretariat, and Legon: Department of Geography and Resource Development, University of Ghana.

Blaikie, P. and Brookfield, H., eds. 1987. Land Degradation and Society. London and New York: Methuen.

Boserup, E. 1965. The Conditions of Agricultural Growth: The Economics of Agrarian Change Under Population Pressure. Chicago: Aldine.

Brookfield, H. 1993a. What PLEC is about. PLEC News and Views 1: 2-5.

Brookfield, H. 1993b. Notes on the theory of land management. PLEC News and Views. 1: 28-32.

Dickson, K.B. and Benneh, G. 1988. A New Geography of Ghana. London: Longman.

Ehrlich, P.R., Ehrlich, A.H. and Holdren, J.P. 1977. Ecoscience: Population, Resources, Environment. San Francisco: W.H. Freeman.

Environmental Protection Council. 1991. Ghana Environmental Action Plan, No. 1. Accra.

Gyasi, E.A. 1976. Population pressure and changes in traditional agriculture: case study of farming in Sekesua-Agbelitsom, Ghana. Bulletin of the Ghana Geographical Association 18: 68-87.

Hill, P. 1963. The Migrant Cocoa Farmers of Southern Ghana: A Study in Rural Capitalism. London: Cambridge University Press.

Soil Research Institute. 1971. Soil Suitability Map of Import Substitution Crops in Ghana. Kumasi Soil Research Institute, and Accra: Survey Department.

Turner, B.L., Clark, W.C., Kates, R.W., Richards, J.F., Mathews, J.T., and Meyer, W.B., eds. 1990. The Earth as Transformed by Human Action. Cambridge: Cambridge University Press.

6: A multidisciplinary integrated methodology

Field study

Edwin A. Gyasi and Lewis Enu-Kwesi

The biophysical environment is composed of a diversity of biotic and abiotic elements which, like the natural and social processes leading to environmental change, are interrelated in a complex system. Therefore, in order to enhance a balanced understanding of this complex situation, the study of environmental change in Ghana's forest-savanna zone followed a multidisciplinary integrated approach involving collaborative work by our interdisciplinary team of natural and social scientists,! with a focus on the study sites Yensiso, Amanase and Sekesua (fig. 5.1, p. 39; figs. 6.1, 6.2 and 6.3). This approach also held promise as a costeffective means of generating relevant socio-economic and biophysical environmental information that was lacking in the study area, as is generally the case in developing countries.

The study drew on available literature, and on data from fieldwork focused on environmental perceptions, adjustment strategies and the range of options available to a mixture of owner and tenant farmers, including migrants.

Because of the paucity of available historical records and the short study report delivery period, the main study time frame was limited to 1960-93.

Field study

In-depth field study concentrated at the three sites, Yensiso, Amanase and Sekesua, located between 60 and 120 km inland by road from Accra. They were inhabited before or from the year 1910, when the cocoa boom was well under way in Ghana.

Yensiso site in the Akuapem district, cradle of Ghana's crucially important cocoa industry, covers the Yensiso, Adenya, Gyamfiase and Kokormu cluster of villages occupied predominantly by the native Akuapem and Ayigbe and Ewe migrant tenants. Amanase site in the historically important cocoa district in southern Akyem covers the juxtaposed villages Amanase and Whanabenya, settled by migrant Akuapem and Siade/Shai landowners, and by a mixture of other migrants, including Ayigbe and Ewe tenants. Sekesua site in a migrant Krobo district covers the adjacent villages Sekesua and Osonson. These areas had attracted a certain amount of research that could form a basis for further work to inform land use and environmental policy (Field 1943; White 1956; Hill 1963; Huber 1963; Hunter 1963; Gyasi 1976, 1979; Gyasi et al. 1990; Gyasi 1991; Amanor 1994; Gyasi 1994b, 1996).

Figure 6.1 Yensiso: Land Use and Cover (Source: 1974 Aerial Photographs Supplied by the Survey Department, Accra)

Figure 6.2 Amanase: Land Use and Cover (Source: 1974 Aerial Photographs Supplied by the Survey Department, Accra)

The field study to generate firsthand information was carried out on a team basis among the interdisciplinary research group by rapid rural appraisal and more deliberate methods in October 1993. Work included group discussions; the popular questionnaire and non-questionnaire interviewing by sample; ground transect involving quadrat sampling and visual observations; and market survey (Gyasi 1994a). Other sources of information included historical records and aerial photographs. These variously assembled data were analysed by laboratory, statistical, cartographic and other techniques. In so doing, we drew on various ideas concerning the evaluation of sustainability and unsustainability.

Figure 6.3 Sekesua: Land Use and Cover (Source: 1974 Aerial Photographs Supplied by the Survey Department, Accra)

The group discussion and transect methods are singled out for discussion because of space limitations, and also because they appear to be particularly efficient for studying agroenvironmental trends and would, therefore, appear to warrant more publicity than the other, better known methods.

Group Discussion

The small farmers who are the major users and, therefore, the principal modifiers of the biophysical environment were the primary target of the survey by group discussion and the other methods.

Table 6.1 Distribution of Farmers with Whom Discussions Were Held on a Group Basis

Site Men Women Total
Yensiso: Yensiso village, Kokormu and Gyamfiase 50 35 85
Amanase: Amanase village and Whanabenya 35 15 50
Sekesua: Sekesua village and Osonson 40 20 60
Total 125 70 195

1. Figures are approximate.
2. In two cases, there was a sprinkling of women among the predominantly male groups.

For the purpose of the group discussion, our original plan was to segregate the farmers into the following four groups: elderly males including the chiefs; young males; elderly females; and young females. However, because of time constraints and difficulties in mobilizing the farmers, it was found necessary to combine these four groups into two principal ones, males and females. In two cases, the men and the few women had, unavoidably, to be combined into one group because of a severe time limitation.

We assumed, a priori, that the farmers' perception of their agroenvironmental situation and changes therein would show significant variations between the sexes, and between the different age categories, because of differences in their socioeconomic role, experiences and aspirations, hence the segregation.

Using a check-list of relevant agroenvironmental parameters and a cassette recorder, we held separate discussions with each of the various groups of men and women farmers, totalling approximately 200 in the three study sites, with one or more of us leading or moderating the discussion (table 6.1). These discussions were held in the mornings on non-farming days, or on the market day, when the farmers could easily be rallied by public notification through the chief, chief farmer and other community leaders.

On the whole, the information obtained through the group discussions was similar to that obtained through the individual interviewing by the structured questionnaire method. Both methods revealed a popular awareness of major changes, generally of a negative character, in the biophysical environment. They also revealed a popular awareness of some possible solutions to the problems, and a general willingness to participate in corrective programmes. However, evidently because of the debate that it engendered among the broad spectrum of farmers, the group discussion approach generated more information, apparently of greater reliability, about changes in biodiversity, including reduction in the quantity and variety of wild mushrooms, plants and animals, and in traditional crops and farming systems, as reported in ensuing chapters. Moreover, the group discussion was faster because it did not entail disparate individual discussions with farmers in their scattered households, as was the case with the structured questionnaire method.

An important finding from the group discussion was that the women, when mixed with the men, hardly spoke. However, they opened up when discussions with them excluded the men, especially their husbands. An illustrative case is recalled. It emerged, during discussion with an exclusively female group, that one member, a young woman, was expecting her fifth child, despite her complaints of overpopulation, poverty and difficulty in caring for her four children. With a dare, a male moderator attributed her obviously high birth rate to overindulgence in nocturnal matrimonial entertainment occasioned by the boredom associated with the lack of electricity and alternative entertainment in the village; whereupon the young woman promptly responded that the boredom and, hence, the overindulgence the moderator had alluded to, were not limited to the night, but extended to the day as well! Such is the kind of frank free-flowing information that group discussions could elicit.

The group approach confirmed our original hunch of important differences in the environmental perceptions between the sexes. For example, when talking about the effects or symptoms of environmental degradation, the women emphasised a shortage of firewood, a household item which, traditionally, the women are required to furnish; while the men emphasised the proliferation of weeds, e.g. C. odorata, whose clearance is, by custom, the responsibility of the men. Furthermore, because of its participatory character, this approach appeared to enhance researcher-target group interaction. This underscores the great potential of group discussion as a tool for sustainable community-based environmental management programmes.

Ground Transect

A complementary method of surveying vegetation and land use in different ecosystems is ground transect or traverse across the agroecological landscape. This method is greatly facilitated by the use of quadrats along the transect line, although, it should be noted, the quadrat method could be used independently of the transect method.

The multidisciplinary team (composed of a botanist, soil scientist, and geographers specializing in land use and agricultural systems, all backed by technicians) employed a combination of transect and quadrat methods for the survey of the agroenvironmental conditions along footpaths radiating up to approximately 2 km each from the following villages:

Overall, a total of about 5 km was traversed.

Ideally, as briefly argued below, the transect should have followed a straight linear distance. However, as this approach would have entailed cutting through the bush at considerable cost in time, which we could ill-afford in view of the severe time limitation for our study report, we used the pre-existing footpaths or roads devoid of major obstacles.

Along the traversed paths, distances were measured by the chain and tape, while observations on soils, plants, farms, fallow lands and other agroecological conditions were made by the eye, by instrument, or by counting, often within rough-and-ready quadrats measuring approximately 30 x 30 m2.

Although the transect method employed generated considerable useful information at little cost in time and money, it nevertheless raised several issues, including the following:

Typically, footpaths are crooked, reflecting, as they generally do, lines of least resistance to human movement, and not necessarily the typical biophysical and agricultural conditions of the study site. Therefore, transects along footpaths might give a biased or distorted picture of the general agroenvironmental situation. A more objective alternative would seem to lie in a linear transect moving in a direction that, on the basis of aerial photographs, satellite images and reconnaissance field surveys, including discussions with the local inhabitants, promises a balanced representation of the general agroecological (including land use and cover) conditions or contrasts.

The optimal transect length might be 4-5 km, which is considered to be the maximum distance that could be conveniently walked in a day for farming purposes.

As for interesting peculiar features far removed from the traverse path, these might be singled out for survey by offsets and other related techniques despite their great deviation from the path.

A 1 x 1 m2 quadrat would seem to be appropriate for a sample survey of species characteristics in terms of type, frequency, dominance etc., while a 25 x 25 m2 quadrat appears adequate for the survey of trees irrespective of height.

There is no easy answer to the question of quadrat sample size or number. However, a general statistical rule is to avoid the following:

In sum, the optimal sample size is the one that minimizes, at the least conceivable cost, the margin of error to a reasonable or tolerable level, which can be expressed in terms of confidence limits.

Assuming that L is the tolerable error in the sample mean (X) and there is a 5 per cent chance of the actual error not exceeding L, then the required sample size n could be represented thus:

where n = the required sample size; a = the population standard deviation; L = the allowable error or given or acceptable limit of error.

A requirement for the operationalization of this equation is an estimate of the population standard deviation (s), which could be guessed, with a fair degree of accuracy, from the results of previous samples of a similar character. In order to expedite our work in the wake of the severe time constraint, the quadrats were limited to one side of the transect path. However, a more thorough or broadly based quadrat survey might better be earned out along both sides of the transect, either continuously or, more realistically, in an alternative or staggered formation. However, this and the other issues raised above require further investigation.


The multidisciplinary integrated approach has much promise as a cost effective method of studying biophysical and agricultural characteristics of the landscape. A key to its successful implementation lies in close cooperation and mutual understanding among the different specialists constituting the multidisciplinary research team.


I. E.A. Gyasi (geography: agricultural land-use systems, rural change); G.T. Agyepong (geography: land-use ecology, remote sensing); E. Ardayfim-Schandorf (geography: gender and environmental change); L. Enu-Kwesi (botany: plant physiology); J.S. Nabila (geography: population, medical geography); E. Owusu-Bennoah (agriculture: soil chemistry and fertility).


Amanor, K.S. 1994. Ecological knowledge and the regional economy: environmental management in the Asesewa district of Ghana. Development and Change 25(1): 4167.

Bailey, N.T.J. 1965. Statistical Methods in Biology. London: English Universities Press. Blalock, H.M. 1960. Social Statistics. New York: McGraw-Hill.

Field, M.J. 1943. The agricultural system of the Manya-Krobo of the Gold Coast. Africa 14(2): 54-65.

Gyasi, E.A. 1976. Population pressure and changes in traditional agriculture: case study of farming in Sekesua-Agbelitsom, Ghana. Bulletin of the Ghana Geographical Association 18: 68-87.

Gyasi, E.A. 1979. Distance as a factor in agricultural land use: case study of farming in Sekesua-Agbelitsom, Ghana. Land Administration Journal 1 (2): 20-36.

Gyasi, E.A. 1991. Communal land tenure and the spread of agroforestry in Ghana's Mampong valley. Ecology and Farming 2: 16-17.

Gyasi, E.A. 1994a. Research execution: experiences of social scientists. In: M.E.K. Dakubu and F.S. Tsikata, eds., University of Ghana Research and Conferences Com mittee Proceedings of a Seminar on the Conduct of Research: From Formulation to Dissemination, 54-60. Legon: University of Ghana.

Gyasi, E.A. 1994b. Adaptability of African communal land tenure to economic opportunity: example of land acquisition for oil palm farming in Ghana. Africa 64(3): 391405.

Gyasi, E.A. 1996. Planning agroforestry dissemination for sustainable environmental use: lessons from an NGO project in Ghana. In: Global Environmental Change, proceedings of IGU Seminar on Monitoring Geosystems: Perspectives for the 21st Century, 6-9 December 1991, University of Delhi, New Delhi. Forthcoming.

Gyasi, E.A., Amaning-Kwarteng, K. and Oware-Gyekye, L. 1990. Mampong valley agroforestry project baseline and evaluation survey report for the Ghana Rural Reconstruction Movement. University of Ghana, Legon. Unpublished.

Hill, P. 1963. The Migrant Cocoa Farmers of Southern Ghana: A Study in Rural Capitalism. London: Cambridge University Press.

Huber, H. 1963. The Krobo: Traditional Social and Religious Life of a West African People. St. Augustin near Bonn, Germany: Anthropos Institute.

Hunter, J.M. 1963. Cocoa migration and patterns of land ownership in the Densu valley near Suhum, Ghana. Transactions and Papers, Institute of British Geographers 33: 61-87.

Poole, R.W. 1974. An Introduction to Quantitative Ecology. New York: McGraw-Hill.

White, H.P. 1956. Internal exchange of staple foods in the Gold Coast. Economic Geography 32: 115-25.

Contents - Previous - Next