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The context

1: General background
2: People, land management and environmental change: Conceptual background, with focus on Africa
3: Indigenous African farming systems: Their significance for sustainable environmental use (Keynote address)
4: Criteria for designing sustainable farming systems in tropical Africa

1: General background

Ecological setting
Farming systems

Edwin A. Gyasi

West Africa is a heterogeneous region of 6 million km2, some 200 million inhabitants and a three per cent annual population growth. It has a dominantly rural economy centred on agriculture that traditionally is adapted closely to the dynamic biophysical environment (fig. 1.1). The status of the biophysical environment is, therefore, crucial to the agriculture, the economies and the general development process in West Africa.

Ecological setting

West Africa lies between the Gulf of Guinea and the southern edges of the Sahara desert. I It is made up largely of an ancient Precambrian land mass, rising from under 50 m in the narrow coastal lowlands to about 600 m in the dissected interior plateau. Soils vary from nutrient-deficient coastal sands, plateau laterites and saline desert soils, through waterlogged coastal swampy soils, dry savanna and desert soils, including potentially rich loess, to fertile alluvium and humic forest soils.

Climatically, the region is characterized by consistently warm temperatures and by a rainfall ranging from under 250 mm to over 3,000 mm per annum. Seasonal rainfall trends, including the unimodal and bimodal patterns, are closely associated with the seasonal migration of the dominant north-easterly dry continental and south-westerly humid maritime air masses. Rainfall and humidity decrease northward, and there is a close correlation with the generally latitudinal alignment of the natural vegetation, which varies from forest to scrub.

The region may be divided into the following major ecological zones: rain or humid forest; forest-savanna ecotone; savanna; sahel; and desert (fig. 1.1).

Figure 1.1 Major Ecological Zones of West Africa

The rain forest is characterized by high humidity, and a yearly minimum 1,500 mm rainfall which occurs in two distinct seasons. Nutrient leaching is prevalent from the rich humus which is derived from the dense forest of lianas, bush and tall trees such as Milicia excelsa. A profusion of fauna helps to make the rain forest the most biologically diverse zone. The inhabitants subsist upon this rich biodiversity, and on the cultivation of tubers, plantains and tree crops, with livestock featuring only as a minor component. More of West Africa's population is concentrated in the rain forest zone, and in the adjoining swampy mangroves and sandy coconut-growing coastal areas, than in any other. This population feature relates to the forest resources, and to the fishing and export-import opportunities offered by the sea. It makes this zone crucially important to protect and to research for viable land use options.

The forest-savanna ecotone is made up of a mosaic of forest and savanna species, and characterized by a bimodal 1,300-1,500 mm annual rainfall. It is found at both high and low elevations in a zone transitional between rain forest and dry savanna. Reportedly once covered by high forest, the forest-savanna ecotone is increasingly dominated by secondary regrowth, by invasive herbaceous species such as the weed Chromolaena odorata, and by savanna grasses such as Imperata cylindrica; hence the frequent designation of this ecological type as "derived savanna." Farming is primarily for seasonal food crops and vegetables, perennial tree crops, and for livestock. This range of land use relates to the transitional nature of the ecosystem, but also underscores the dynamic changes in the biophysical environment which make it essential that the forces for change and continuing threat to biodiversity and the other environmental resources be researched.

The savanna ecosystem, with its mixture of grasses and short trees, notably Parkia clappertoniana, Butyrospemum and Adonsonia digitata, and an annual 800-1,500 mm unimodal rainfall, supports grain farming and livestock on an extensive plateau north of the forest-savanna zone, and on a smaller plain centred around Accra along the coast of Ghana. In this savanna zone is the major cattle belt of West Africa. The low rainfall and the low humic content of the soils limit the yields of seasonal food crops and vegetables, and render this zone one of the most ecologically sensitive and most prone to deleterious change.

The most extensive ecosystem is the sahel, which extends northwards of the savanna zone on an elevated plain with isolated hills, to the southern fringes of the Sahara desert. It receives 200-500 mm of highly unimodal rainfall, has hardy stunted trees, notably Acacia spp., and short grasses, which form the basis of the essentially livestock economy. Beyond this zone, in the extreme north, lies the true desert.

West Africa remains rich in both domesticated and non-domesticated plants and animals which, besides their economic value, perform vital ecological functions such as pollination, seed dispersal, decomposition and biomass recycling. These rich biological resources, together with the time-tested diversified indigenous systems of managing them, have, however, come under increasing threat (Hence 1964; Mountjoy and Embleton 1967; Pritchard 1979; Okigbo 1993; United Nations Environment Programme 1994).

Farming systems

In the West African context, farming has evolved from indigenous migratory systems to increasingly sedentary systems based upon cropping, exotic systems such as plantations and local adaptations, all of which have large implications for small-scale peasant farming, the environment and biological diversity.

The main indigenously developed farming systems include temporary intercropped fallow, permanent intercropping, livestock farming and mixed farming, all of which exhibit a rich agrodiversity, a term employed to describe the many variable and dynamic ways whereby farmers use the natural diversity of the environment for production, including their choice of crops and animals, management of biodiversity within them, and management of land, water and various other living and non-living components of the resource base (Brookfield 1994; Brookfield and Padoch 1994). Such time-tested indigenous land management systems include rotational agroforestry, intensive kitchen and home gardens and compound farming, which are inherently self-regenerative and protective of the soils and biological diversity because of their close adaptation to the natural biophysical environment and minimal dependence upon artificial external inputs. This cultural adaptation derives from the small traditional farmers' intimate understanding of the agroenvironment as a delicately structured ecosystem whose survivability depends upon minimal disturbance.

Population growth, social change, migration to new areas and the degradation of earlier frontier regions, shifts in cash cropping and the impact of policies adopted by the colonial and post-colonial governments have greatly affected the sustainability of farming systems in most parts of West Africa. Farmers have adapted their management strategies to these constantly changing conditions with greater success in some areas than in others. Everywhere, however, they demonstrate a profound knowledge of the natural environment and, where there is opportunity and where they are not constrained by exactions arising from tenancy and other pressures, there is evidence of successful management even in degraded areas (Benneh 1972; Okigbo 1993; Amanor 1994; United Nations Environment Programme 1994).


Thus, amid the great variety of land uses and practices in West Africa, there is a fund of knowledge which could inform the better management of land and related resources for small-scale producers, while at the same time protecting inherent biodiversity and environmental integrity. However, this rich cultural heritage, and the diversified biophysical environment, are getting increasingly transformed and forms and by forces that still remain imperfectly understood; hence this book, which examines changes in the biophysical environment and farmers' responses to them in West Africa, with special reference to Ghana.

Following Gyasi et al. (1994,1995) a basic hypothesis of this book associates the agroenvironmental changes principally with anthropogenic stress or the impact of human society, especially through economic activities, notably production, which, in turn, is strongly influenced by people's demands or the pressure of population, and by various other factors including technological capacity, social organization, the political economy and the inherent resiliency of the environment itself. A related hypothesis is that, on the whole, in West Africa as in other developing or underdeveloped regions, the agroenvironmental change resulting from the pressure of production is degradational rather than aggradational in character, and that this is so mainly because of poverty and the low levels of technology. These hypotheses are rooted in the still contentious theory by Boserup (1965) and other scholars (Grigg 1976; Gyasi 1976; Ehrlich et al. 1977; Blaikie and Brookfield 1987; Turner et al. 1990; Fairhead and Leach 1995).


1. This subsection on "ecological setting" and portions of the subsection on farming systems are derived largely from a PLEC research extension proposal prepared by this author with the support of a team of PLEC researchers based at the University of Ghana, Legon.


Amanor, K.S. 1994. The New Frontier: Farmers' Responses to Land Degradation: A West African Case Study. Geneva: UNRISD, and London: Zed Books.

Benneh, G. 1972. Systems of agriculture in tropical Africa. Economic Geography. 48(3): 24457.

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. 1994. Population, land management and environmental change programme. South-South Perspective 1 (October): 20.

Brookfield, H. and Padoch, C. 1994. Appreciating agrodiversity: a look at the dynamism and diversity of indigenous farming practices. Environment 36(5): 7 11, 37-45. Ehrlich, P.R., Ehrlich, A.H. and Holdren, J.P. 1977. Ecoscience: Population, Resources, Environment. San Francisco: W.H. Freeman.

Fairhead, J. and Leach, M. 1995. Enriching landscapes: social history and the management of transition ecology in Guinea's forest-savanna mosaic. Africa. Forthcoming.

Grigg, D.B. 1976. Population pressure and agricultural change. Progress in Geography: International Reviews of Current Research 8: 135-76.

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., Agyepong, G.T., Ardayfio-Schandorf, E., Enu-Kwesi, L., Nabila, J.S. and OwusuBennoah, E. 1994. Environmental Endangerment in the Forest-Savanna Zone of Southern Ghana. A research study report for the United Nations University (UNU), Tokyo, Japan, in respect of the UNU Collaborative Research Project on Population, Land Management and Environmental Change (PLEC), January, Legon.

Gyasi, E.A., Agyepong, G.T., Ardayfio-Schandorf, E., Enu-Kwesi, L., Nabila, J.S. and OwusuBennoah, E. 1995. Production pressure and environmental change in the forest-savanna zone of southern Ghana. Global Environmental Change 5(4): 35566.

Hance, W.A. 1964. The Geography of Modern Africa. New York: Columbia University Press.

Mountjoy, A.B. and Embleton, C. 1967. Africa: A New Geographical Survey. New York: Praeger.

Okigbo, B. 1993. Towards sustainable environmental and resource management futures in SubSaharan Africa. Paper presented at the Conference on Sustainable Environment and Resource Management Futures for Sub-Saharan Africa, University of Ghana, Legon, Accra, 22-26 March.

Pritchard, J.M. 1979. Landform and Landscape in Africa. London: Edward Arnold.

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.

United Nations Environment Programme. 1994. The Convention on Biodiversity: Issues of Relevance to Africa. Regional ministerial conference on the Convention on Biological Diversity, Nairobi, October.

2: People, land management and environmental change: conceptual background, with focus on Africa

Background and context
Population, agriculture and environment in sub-Saharan Africa
Objectives of PLEC
PLEC in Africa
International collaboration for sustainable development

Juha I. Uitto

Background and context

In the early 1990s, the issues pertaining to the population-environment nexus moved into the forefront of international attention. Yet, systematic and rigorous scientific analysis based on a solid theory has been sporadic. Despite a growing literature on the topic, much of the discussion is based on somewhat simplistic, linear notions of the relationship between population growth and environmental degradation.

Agenda 21, the major outcome of the United Nations Conference on Environment and Development (UNCED) organized in Brazil in June 1992, outlines the main issues, objectives and actions required to achieve, or at least move towards, sustainable development as we approach the next century (UN 1992). Chapter 5 of Agenda 21, on "Demographic Dynamics and Sustainability," identifies the strengthening of research programmes that integrate population, environment and development as a central means of implementation of the international agenda. Enhancement of research by international institutions and networks of experts, as well as a multidisciplinary approach in linking this research to action, are needed in order to achieve this goal. Furthermore, chapters 14 and 15, on "Promoting Sustainable Agriculture and Rural Development" and "Conservation of Biological Diversity," are central to our concerns here.

Agenda 21 also provides guiding principles for the United Nations and its agencies, including the United Nations University (UNU), for devising plans for follow-up to UNCED and for planning their environmental programmes. Following UNCED, UNU appointed a high-level advisory team, consisting of representatives of key UN agencies, NGOs, academia and the international community, to take a critical look at how the University could best devote its resources, taking into account its strengths and comparative advantages, and play a role in fulfilling the recommendations of the Earth Summit. This resulted in the development of the University's programme on environmentally sustainable development, the "UNU Agenda 21" (UNU 1993).

The "UNU Agenda 21" emphasizes, i.a., the importance of local and regional sustainability through appropriate environmental and resource management. It aggregates issues of environmentally sustainable development from the entry point of the capacity of ecosystems and their ability to support, resist or recuperate from the long-term impact of human activities. An essential approach is to focus on integrated studies of geographically delineated fragile ecosystems and vulnerable regions. The work encompasses research into both the natural and social sciences.

A central objective of UNU's work is to promote institution and capacity building in developing countries. The collaboration of academic institutions and scholars from both the North and the South within UNU's research programmes, as well as the University's postgraduate education and training activities, are geared towards reaching these goals.

As a response to the need for a systematic study of the management of land and biological resources in the tropical and subtropical areas of the world, which are facing growing production and population pressures, the international collaborative project on "People, Land Management and Environmental Change" (PLEC) was initiated.

Population, agriculture and environment in sub-Saharan Africa

Agriculture is the basic sector of Africa's economy on which the majority of people depend for their livelihood. Consequently, much attention is dedicated to issues pertaining to sustainable agricultural development, and to the degradation of the production base. The critical relationship between population growth and the consumption of resources, including issues such as pressure on cultivable land and the demand for fuelwood, is recognized as one of the driving forces behind regional change (Uitto and Manshard 1993). It must, however, be emphasized that the impact of population growth varies geographically depending on socioeconomic and technological factors.

The question of the impacts of population growth on the environment and management of resources is subject to an ongoing debate (Ness et al. 1993). Opposing views have been argued, often based on the ideology of the writer and the perspective from which the problematique is observed. One important distinction must be made between the macro and micro views; between the global and the local levels.

The current orthodoxy in the environmental movement seems to advocate the view that population growth is intrinsically detrimental to the environment (Brown and Kane 1994). More people pollute and consume more resources. This view generally prevails also among international development institu tions, such as the World Bank and the United Nations Population Fund, that finance and manage projects and programmes in the developing countries (Myers 1991; WB 1994).

While at the global level there should be no doubt that population increase is one of the driving forces of environmental change, on local levels the relationship becomes far less clear. As some economists have argued, population growth has frequently acted in history as a stimulant for new innovations that have prompted technological development and, ultimately, the well-being of the population. This argument, first put forward by Boserup (1965), has seen population and human ingenuity as the ultimate resource (Simon 1981).

This latter view has been supported by a number of recent case-studies carried out in Africa (Turner et al. 1993). According to the argument, in Africa, where population densities are generally rather low, population growth and the resultant intensification of land use have in some cases resulted in actually improved environmental management and agricultural sustainability. In a well-publicized case, Tiffen et al. (1994) focus on an area in Kenya where the rapid increase of population forced the farmers to introduce improved practices and new techniques to prevent erosion and maintain soil fertility in order to sustain food production in the area.

These cases where population growth has resulted in a better environment need not be challenged. What needs to be emphasized, nevertheless, is that they also do not represent the full picture. As shown by other studies in different environments (e.g., Gyasi et al. 1995), the reverse is also true.

A central thesis here is that there is a great deal of regional and local variation in the so-called population-environment nexus, based on physical as well as social, economic, cultural and political conditions. Therefore, there is a need for a systematic and detailed analysis that takes this variation into account.

Objectives of PLEC

PLEC emphasizes the complex human-environment interrelationship within managed agroecosystems, and the impacts of increased population and production pressure on the management of land and biological resources. PLEC is a relatively new effort, but it builds upon the work carried out by the UNU in the past. The issue of sustainable land management has been central to numerous UNU research efforts (Manshard and Uitto 1993; Uitto 1995).

PLEC is a field-based international collaborative project established with the aim of fostering South-South cooperation. Six research clusters have been established in the tropical and subtropical areas of Asia, Latin America and Africa, with the aim of undertaking targeted, action-oriented research. The project also places emphasis on capacity building in the participating institutions and countries. It is intended to strengthen national abilities to manage biodiversity and environmental degradation, and it also seeks to enhance the sustainability of natural resources and ecosystem use (Brookfield 1995). A comparative perspective across the clusters is achieved through a regular two way feedback process, cross-cluster meetings, and interactive review of project design, methodologies and results.

The concepts central to PLEC are production pressure and agrodiversity and the effects on the sustainability of the world's food production. The project is concerned with the ecological changes caused by and affecting small- and mediumscale farming operating under conditions of rapid population growth, socioeconomic change, and environmental stress. "Agrodiversity" is defined as consisting of the crop biodiversity used by farmers in their cultivation activities, and the number of wild or semi-domesticated species used for food and other economic products, as well as the entire complex of farmers' management practices (Brookfield and Padoch 1994).

A major part of the problem of biodiversity conservation is located outside of the protected areas, in managed agroecosystems where population growth, commercialization, land degradation and deforestation put severe pressures on sustainability. These areas are far larger in size than protected areas ever can be. Farmers have managed these lands for long periods of time, producing food and other necessities for their families. A common fallacy is to assume that change is a recent phenomenon; change has always been present and sometimes it has been very rapid. Yet, the traditional farming systems have frequently been able to respond successfully to the changing conditions, applying indigenously developed techniques and knowledge. This knowledge is, however, ignored more often than not by modern science and agricultural research and extension systems.

A central objective of PLEC is to bring this knowledge to the forefront in order to find sustainable solutions to the management and conservation of land and agrodiversity. The project is inherently participatory in approach, placing emphasis on working together with the farmers, local officials, NGOs, and other stakeholders to design conservation systems that are also socially, financially and culturally sustainable. These systems should make use of an ecosystemmanagement approach which allows the integration of scientific knowledge of ecological relationships with that of socio-political conditions and values to achieve biodiversity protection and sustainable land management.

PLEC in Africa

Two of the PLEC clusters are located in Africa. A regional conference on sustainable environmental and resource management futures for Sub-Saharan Africa was organized by the UNU in Ghana in 1993. The objective of the conference was to analyse the trends and processes of environmental change in Sub-Saharan Africa, and to identify key issues for achieving sustainable environmental and resource management in the region within the medium-term future of some 20 years (Benneh et al. 1996).

The conference led to the establishment of the West Africa cluster based at the University of Ghana, Legon. Research work focusing on the forest-savanna transition zone in Ghana was soon commenced along the directions defined by PLEC (Gyasi et al. 1995). Later this cluster was expanded to cover other ecological regions in the country, as well as in another West African country, Guinea. The multidisciplinary team now draws upon the expertise available in other institutions in the concerned countries, including the University of Science and Technology in Kumasi, the University of Development Studies in Tamale, and the Université de Conakry in Guinea. The work programme is divided between the dry, subhumid parts of West Africa and the margins of the forest zone. In Guinea, there is also a mountain area that is the focus of research. These areas contain a wide range of indigenous farming systems, which are all under considerable pressure with resultant degradation already visible.

The other African cluster covers the three East African countries of Kenya, Tanzania and Uganda. This region demonstrates a remarkable range of agroecological zones - from humid tropical to near-desert. The research there is also carried out by multidisciplinary teams based at local universities and government institutions. Preliminary results of research have already been published (Kiome and Stocking 1995).

Close collaboration has been established with the UNU Institute for Natural Resources in Africa (UNU/INRA), with headquarters located on the Legon campus in Ghana. Both PLEC and UNU/INRA are concerned with issues related to the sustainability of smallholder agricultural systems, and the preservation of biodiversity - or agrodiversity - within them. Two of the three priority areas of UNU/INRA are soil and water conservation and indigenous African food crops and other useful plants. These are central concerns of PLEC as well. The geographical focus of the two UNU initiatives is partly different. Whereas UNU/INRA is an African regional undertaking, PLEC brings out a comparative viewpoint between Asia, Latin America and Africa.

International collaboration for sustainable development

International cooperation and networking in research and training aimed at finding new and innovative solutions to problems related to regional environmental and resource management, and at promoting the transfer of knowledge and capacity building, is essential.

The long-term objective of PLEC is to develop models for conservationist, sustainable and participatory ecosystem management in smallholder agricultural areas, stressing the value of farmers' skills and knowledge in the context of agrodiversity. The project seeks to assist the wide adoption of rural development strategies which combine ecologically, economically, culturally and socially sustainable small-farmer agriculture with sustainable management and conservation of biodiversity. The project is highly policy oriented and its results will be fed into policy-making by national and international organ izations with rural and agricultural development and conservation. The ultimate test of the project's success will be the use of its results for guiding the development of these programmes.


Benneh, G., W.B. Morgan and J.I. Uitto, eds. 1996. Sustaining the Future: Economic, Social, and Environmental Change in Sub-Saharan Africa. Tokyo: United Nations University Press.

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

Brookfield, H. 1995. Introduction: PLEC and global environmental change. Global Environmental Change: Human and Policy Dimensions 5(4): 263-66.

Brookfield, H. and C. Padoch. 1994. Appreciating agrodiversity: a look at the dynamism and diversity of indigenous farming practices. Environment 36(5): 6-11, 37-45.

Brown, L.R. and H. Kane. 1994. Full House: Reassessing the Earth's Population Carrying Capacity. New York: W.W. Norton & Company.

Gyasi, E.A., G.T. Agyepong, E. Ardayfio-Schandorf, L. Enu-Kwesi, J.S. Nabila and E. OwusuBennoah. 1995. Production pressure and environmental change in the forest-savanna zone of southern Ghana. Global Environmental Change: Human and Policy Dimensions 5(4): 355-66.

Kiome, R.M. and M. Stocking. 1995. Rationality of farmer perception of soil erosion: the effectiveness of soil conservation in semi-arid Kenya. Global Environmental Change: Human and Policy Dimensions 5(4): 281-95.

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Simon, J. 1981. The Ultimate Resource. Princeton, NJ: Princeton University Press.

Tiffen, M., M. Mortimore and F. Gichuki. 1994. More People, Less Erosion: Environmental Recovery in Kenya. Chichester: John Wiley & Sons.

Turner II, B.L., G. Hyden and R. Kates, eds. 1993. Population Growth and Agricultural Change in Africa. Gainesville, FL: University Press of Florida.

Uitto, J.I. 1995. Population, Land Management and Environmental Change: the genesis of PLEC within the United Nations University programme. Global Environmental Change: Human and Policy Dimensions 5(4): 267-71.

Uitto, J.I. and W. Manshard. 1993. Sustainable environmental and resource management futures for Sub-Saharan Africa. GeoJournal 31(1): 105-6.

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WB. 1994. Population and Development: Implications for the World Bank. Washington, DC: The World Bank.

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