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close this bookSustaining the Future. Economic, Social, and Environmental Change in Sub-Saharan Africa (UNU, 1996, 365 p.)
close this folderPart 2: Environmental issues and futures
Open this folder and view contentsTowards sustainable environmental and resource management futures in Sub-Saharan Africa
Open this folder and view contentsDrought, desertification, and water management in Sub-Saharan Africa
Open this folder and view contentsTropical deforestation and its impact on soil, environment, and agricultural productivity
Open this folder and view contentsThe coastal zone and oceanic problems of Sub-Saharan Africa

(introduction...)

Introduction
The concept of sustainable development and its implications
Driving forces
Levels of environmental effects of human activities and sustainability concerns
Constraints on sustainable development in Sub-Saharan Africa
Recommendations
References

 

Bede N. Okigbo

Introduction

To the layperson, the environment consists simply of anything animal, plant, and mineral, in addition to other things around us such as the atmosphere, sun and, moon. To the ecologist, the environment is a more complex, multifaceted, interlocking, and overlapping phenomenon that is physical, biological, anthropic, and resource generating in nature (Pomeroy and Service 1986). The physical environment consists of: a terrestrial component, made up of land, water, wind, and climatic elements such as solar radiation and temperature; the aquatic component, made up of bodies of water, dissolved and suspended matter, currents, light, and other elements; the resources, made up of food of plant and animal origin, air (including oxygen, nitrogen, and carbon dioxide), water, shelter, etc.; the biological environment or component, consisting of living things made up of a diversity of species and their wide range of characteristics; and last, but not least in importance, the anthropic component consisting of humans and human multisectoral activities in agriculture, building, construction, fishing, hunting, industry, tourism, etc. It is of interest to note that humans and human activities are grouped into a separate category despite the fact that humans are also animals. This is because of the overwhelming influence or effects that humans have on the environment, shaping and conditioning things in the present and in the future. The implication of humans and human activities as a special component of the environment is that they give rise to other environments that are economic, political, and cultural in nature.

Again, to the layperson the above environmental resources (plant, animal, and mineral) are synonymous with natural resources. But, to the resource economist, in the human ecosystem humans assign utility to various elements of the environment, thus conferring on them the role of resources (Chapman 1969). A resource is the result of human interaction with elements of the environment. When humans make use of any element of the environment, thus changing its status to that of a resource that fulfils one or more human needs, this involves a different kind of interaction or interrelationships in which humans play a central role.

A component of the environment that humans use as a resource acquires an economic or rarity value, whose magnitude depends on its nature and the size of the requirements humans place on it, which depend on the size of population using it, humans' needs and desires, and humans' values and skills (Chapman 1969). The implications of this are that the economic value of a resource depends a lot on the magnitude of its reserve(s), its characteristics, including ease of extraction and processing, and the technologies available for rendering it into forms that satisfy human needs. Consequently, according to Chapman (1969):

Resource availability is the result of interactions among the nature and size of humans' requirements, the physical occurrences of the resource, and the means of producing it.

The future availability of resources can be determined on the basis of assessment of:

- the particular combination of economic and technological conditions that determine present production,

- the level of production that would take place under different economic conditions,

- the level of production that could take place under different technological conditions (i.e. types, mixes, sequences, and timing),

- the nature and quantity of the total physical stock of both renewable and non-renewable resources.

The total stock or resource base is the sum of all components of the environment that would be resources if they could be extracted from it.

The resource constitutes the proportion of the total stock that humans can extract and make available under prevailing technological and economic conditions.

The reserve is that proportion of the resource that is known with reasonable certainty to be available under prevailing technological, economic, and social conditions.

The requirements and availability of resources very much depend on their interrelationships with time, space, and technology. The relative importance of time lies in the fact that, whereas certain biological processes take a very long time, some ecological processes may require a relatively short time, and human activities may take only a very short time to change the result of thousands of years of evolution. Furthermore, technological changes occur with time, and the economics of the availability of resources may depend on the distribution in space or distance between sources and where they are used, and the technology available at a given time or stage for facilitating access to the resources.

The importance of science and technology then lies in the fact that, through their applications, we can (a) identify the presence and determine the amount (quantity) and the characteristics (quality) of reserves, (b) conserve/manage them, and (c) process them with increasing cost-effectiveness in order to ensure rational utilization of resources. Management and economics are of importance in that resources are often scarce and/or exhibit inequalities in availability and distribution. Management also is very important in the processing and utilization of scarce resources as cheaply as possible. It is not surprising then that, in sustainable development, there is increasing realization of the interrelationship between economics and ecology. In fact it is for this reason that, in an age of sustainable development, Goodland (1991) maintains that conventional economics and conventional ecology should be integrated into ecological economics (fig. 7.1 and table 7.1).

The complex interrelationships that exist among resources and humans in various sectoral development activities are shown in figure 7.2. It is necessary to emphasize that, in the development process, both general and specialized education are important in our understanding and managing of natural resources. Education provides a solid foundation for the research needed to develop new technologies and expand the frontiers of knowledge, while training is necessary for imparting the skills needed for conservation, management, and rational utilization of resources.


Fig. 7.1 The domains of conventional economics, conventional ecology, environmental and resource economics, and ecologicd economics (Source: Constanza 1991)

The problem of renewable and non-renewable resources

In the development process, strategies and technologies used in the conservation, management, and utilization of renewable resources should be different from those used for non-renewable resources, such as minerals. Non-renewable resources should be conserved and wisely utilized so as substantially to extend the time of their availability and existence. Such a long period of time is necessary for seeking and finding alternatives. Although renewable resources can be regenerated, they have to be conserved and carefully utilized in order to realize their renewability. For example, although the soil is renewable, if it is managed in such a way that rates of loss and degradation exceed the rate of soil formation, the result is lack of renewability and sustainability. Similarly, although plants or animals are renewable, the extermination of certain species that are necessary for their breeding and continuous regeneration may ultimately lead to their extinction. Thus the loss of species or even individuals with unique characteristics results in the loss of their irreplaceable unique genetic information and make-up.

Table 7.1 Comparison of "conventional" economics and ecology with ecological economics

  Conventional" economics "Conventional" ecology Ecological economics
Basic world-view Mechanistic, static, atomistic Evolutionary, atomistic Dynamic, systems, evolutionary
  Individual tastes and preferences taken as given and as the dominant force. The resource base viewed as essentially limitless owing to technical progress and infinite substitutability Evolution acting at the genetic level viewed as the dominant force. The resource base is limited. Humans are just another species but are rarely studied Human preferences, understanding, technology, and organization co-evolve to reflect broad ecological opportunities and constraints. Humans are responsible for understanding their role in the larger system and managing it for sustain ability
Time frame Short Multi-scale Multi-scale
  50 years maximum, 1-4 years usual Days to eons, but time-scales often define non-communicating sub-disciplines Days to eons, multi-scale synthesis
Space frame Local to international Local to regional Local to global
  Framework invariant at increasing spatial scale; basic units change from individuals to firms to countries Most research has focused on relatively small research sites in single ecosystems. but larger scales becoming more important recently Hierarchy of scales
Species frame Humans only Non-humans only Whole ecosystem including humans
  Plants and animals included only rarely for contributory value Attempts to find "pristine" eco-systems untouched by humans Acknowledges interconnections between humans and rest of nature
Primary micro goal Max. profits (firms) Maximum reproductive success Must be adjusted to reflect system goals
  Max. utility (individuals) All agents following micro goals leads to macro goal being fulfilled Social organization and cultural institutions at higher levels of the space/time hierarchy ameliorate conflicts produced by myopic pursuit of micro goals at lower levels, and vice
  All agents following micro goals leads to macro goal being fulfilled. External costs and benefits given lip-service but usually ignored    
Assumptions about technical progress Very optimistic Pessimistic or no opinion Prudently sceptical
Academic stance Disciplinary Disciplinary Transdisciplinary
  Monistic; focus on mathematical tools More pluralistic than economics, but still focused on tools and techniques. Few rewards for comprehensive, integrative work Pluralistic; focus on problems

Source: Constanza (1991).


Fig. 7.2 The interactions among components of natural resources in sectoral development acffvities (Source: B. Brouillette, N. J. Graves, and G. Last, African Geography for Schools, London: Longman; Paris: UNESCO, 1974)

Futures in normal commercial everyday usage are used to designate goods and stocks sold for future delivery. Here the term is used in a prognostic manner to forecast what the future portends in terms of the status of resources and the condition of the environment for future generations as a result of the impacts of multifarious human activities. It requires an assessment of past and present development policies, strategies, technologies, and programmes with regard to the extent to which they have resulted in unsustainability, lack of it, or enhancement of the resource base. A sustainable future will be possible only where appropriate and effective measures are taken now to replace the past and present non-environmentally friendly development policies, strategies, technologies, and programmes, and in addition to introduce the requisite changes in attitudes, morals, and behaviours in different cultures.

The concept of sustainable development and its implications

Definition

Sustainable development as a concept and development paradigm for lasting progress was originally defined by the World Commission on Environment and Development (WCED) to mean "development that meets the needs of the present generation without compromising the ability of future generations to meet their own needs" (WCED 1987). The Commission further added that "this concept does not imply limits - not absolute limits but limitations imposed by the present state of technology and social organization on environmental resources and by the ability of the biosphere to absorb the effects of human activities." This definition implies that sustainable development involves policies, strategies, and programmes that do not make it more difficult for the development process to be continued by future generations than it is for present generations. It would appear that this definition emphasizes the objectives to be achieved rather than explicitly defining sustainable development.

One of the earlier concepts of sustainable development was advanced by Sachs (1973), who used the term eco-development. Eco development was defined to consist of strategies designed for particular eco-zones with a view to:

(a) making fuller use of specific resources in each eco-zone in order to meet the basic needs of its inhabitants while safeguarding the long-term prospects by rational management of these resources instead of their destructive exploitation;

(b) reducing to a minimum the negative environmental effects and even as far as possible using waste products for productive purposes;

(c) designing adequate technologies for achieving these goals. (Ominde 1977)

There does not appear to be any substantial difference between eco-development and sustainable development, both of which embody environmental concerns in development activities and programmes. The real difference lies in the fact that, whereas the former was a development paradigm born at the beginning of the period of environmental and "limits of growth" concerns, the latter came at a time when environmental activism and pressures from green parties all over the world necessitated not only a new development paradigm but a slogan and buzzword christened sustainable development.

The United Nations Environment Programme (UNEP 1992) argues that the WCED (1987) definitions of sustainable development have been criticized as ambiguous and confusing because "sustainable development," "sustainable growth," and "sustainable use" have been used interchangeably even though they do not have the same meaning. "Sustainable growth" is regarded as contradictory in that nothing physical can grow indefinitely, while "sustainable use" is applicable only to renewable resources in terms of "using them at rates within the capacity for renewability." Based on these arguments, UNEP (1992) put forward the following relevant definitions:

Sustainable development means improving the quality of human life while living within the carrying capacity of supporting ecosystems.

Sustainable economy is the product of sustainable development; it maintains its natural resource base and it can continue to develop by adapting to changing circumstances and through improvements in knowledge organization, technical efficiency, and wisdom.

Sustainable living indicates the lifestyle of an individual who feels the obligation to care for nature and for every human individual, and who acts accordingly.

According to MECCA (1992), sustainable development is said to exist if each generation per capita inherits a more valuable stock of capital (human-made and natural) than the earlier generations. This definition raises the question of what are valuable resources and the problem of how far one can be more specific about sustainability without bringing in value judgements on what is important for ensuring a given quality of life.

Recently, Benneh (1993) presented an African concept of sustainability that constitutes an extension of the WCED (1987) definition of sustainable development by emphasizing that sustainable development is not simply a question of managing resources in a manner that meets current needs while not making it more difficult for future generations to meet theirs. Rather, it is a strategy of resource management that regards the capital stock as a baton in a relay race handed down to us by our ancestors, and it is our duty to ensure that it is successfully transferred to future generations more or less intact and without much decline in value.

Although this concept, like the WCED (1987) definition, does not specifically indicate what sustainable development entails, it raises an issue that the WCED (1987) discussed but did not include or allude to in its definitions. This is the problem of transition, which takes into account the past, the present, and the future. It is perhaps the most difficult challenge and implication of sustainable development: it recognizes that maintenance of environmental quality, productivity potentialities, biological diversity, and resilience of ecosystems should go hand in hand with development activities, but it does not stipulate how the necessary changes from a past of exploitative squandering of the earth's natural resources and degradation of the environment to a sustainable future can be effected through the present period of transition when the necessary changes in attitudes, ethics, morality, culture, and lifestyles against the driving forces of polarization and momentum of the modernization process and other change factors discussed later will be made.

In this paper, sustainable development is defined as consisting of policies, strategies, plans, production systems, and technologies used in executing projects and programmes aimed at satisfying real human needs in perpetuity while maintaining environmental quality, biodiversity, the resilience of ecosystems, and the welfare of all organisms by integrating conservation, management, and rational utilization of resources at individual, institutional, community, national, regional, and global levels. Conservation here, according to Jacobs (1988), is an indispensable part of a wide field known as "the wise utilization of natural resources" aiming at utilization ad infinitum. It aims at (a) maintaining essential ecological processes and life-support systems, (b) preserving genetic diversity, and (c) ensuring the sustainable utilization of species and ecosystems.

What sustainable development entails

Requirements for sustainable development, according to WCED (1987), include: a political system that secures effective citizen participation; an economic system that is able to generate surpluses and technical knowledge on a self-reliant basis; a social system that provides for solutions for tensions arising from disharmonious development; a production system that respects the obligation to preserve the ecological base for development; a technological system that can search continuously for new solutions; an international system that fosters sustainable patterns of trade and finance; and an administrative system that is flexible and has the capacity for self-correction.

Caring for the Earth: A Strategy for Sustainable Living (IUCN/ UNEP/WWF 1991) enunciated nine principles for sustainable development:

Respect and care for the community of life.
Improve the quality of human life.
Conserve the earth's vitality and diversity.
Minimize the depletion of non-renewable resources.
Keep within the earth's carrying capacity.
Change personal attitudes and practices.
Enable communities to care for their own environments.
Provide a national framework for integration, development, and conservation.
Create a global alliance.

It is obvious from the above that sustainable development not only entails the embodiment of environmental concerns in development activities and technology use but also necessitates changes in attitudes, behaviour, philosophy, moral and ethical values, religious practices, and relationships among human beings and between humans on the one hand and organisms or things on the other at the local, national, regional, and global levels.

Implications and challenges in sustainable development

In addition to the above requirements for sustainable development, there are several implications of the sustainable development paradigm that pose serious challenges for mankind now and in the future. Some of these implications and challenges are discussed in Pearce et al. (1990), Goodland et al. (1991), and Sachs (1992). Only salient aspects of these are considered here.

According to Pearce et al. (1990), a key prerequisite for sustainability is maintaining the constancy of the stock of natural resources and environmental quality. But because this condition has already been breached, in that the environment in many situations has become degraded by human activities, the problem of maintaining the constancy of the capital stock is not just one of stopping further environmental degradation but undoubtedly one of enhancing the environment. The implications of this are addressed from different viewpoints by the Brundtland Report (WCED 1987), which stipulates that sustainable development requires non-depletion of the natural capital stock as indicated in the World Conservation Strategy (IUCN/ UNEP/WWF 1980), although WCED (1987) insists that, if needs are to be met on a sustainable basis, the earth's natural resources have to be both conserved and enhanced. Reasons for conserving the natural capital include moral obligation and the supposed mutual interdependence of development and natural capital conservation.

Goodland (1991) presents very convincing arguments and undeniable evidence to conclude that the limits of growth, in which the earth functions as a source of inputs and sink for waste products, have been reached and that options for ensuring sustainability in future are running out. Evidence for this conclusion includes: (a) over 80 per cent of the earth's net primary productivity is already being consumed to meet humans' food and other needs while population is still increasing, (b) global warming owing to increasing levels of carbon dioxide is already producing adverse climatic effects that threaten humans and various ecosystems, (c) ozone depletion is taking place owing to increasing levels of greenhouse gases (methane, CFCs, and nitrous oxide), which are eating up the protective ozone layer with adverse consequences for humans and other living things, (d) land degradation and loss of soil fertility and productivity make it difficult to produce enough food, feed, and fibre for rising populations of humans and animals, and (e) biodiversity has been lost with increasing deforestation, especially in species-rich tropical ecosystems, with loss of species estimated at 500 per annum.

Daly (1991) notes that the human economy has passed from an era in which human-made capital was the limiting factor to an economic development era in which increasingly scarce natural capital has become the limiting factor. He recommends that priority should be given to "qualitative development" based on more efficient use of energy and natural resources, an increase in end-use efficiency of the product through recycling, and the reduction of waste and pollutants.

Tinbergen and Hueting (1991) as well as Serafy (1991) consider equity issues, sustainability constraints under low rates of economic growth, uneven/varying population growth rates, and the effects of North-South trade on the environment and development in the South. Doubts are raised about the soundness of some WCED (1987) equity considerations in economic growth and the strategies aimed at increasing economic growth and development in developing countries going pari passu with lower non-increasing growth rates in developed countries in order to ensure that developing countries achieve higher per capita income and alleviation of poverty in order to narrow the gap between the rich and the poor countries. The fallacy in this is that, because growth in developed countries has naturally acquired momentum, it is very likely that its rate will continue to rise rather than decrease. Moreover, the intended objective can be achieved only if the developed countries transfer the resources needed to redress the negative effects of richer countries' arrested growth to the developing countries, thereby reducing poverty.

It is observed that the time-horizon of development should be taken into account, for some obvious reasons. First, sustainable development usually aims at a long-term time-frame of several generations, but politicians and policy makers plan on short-term time-frames of four to five years. Secondly, sustainable development that involves many generations or centuries cannot go on indefinitely where both population and per capita use of the earth's finite resources grow significantly. Even where population and economic activities remain static, the accumulation of pollutants and waste will continue to increase with the growth of entropy beyond nature's capacity for self-repair.

The principle of the free market mechanism as a way of creating certain optimal conditions has not often yielded the expected results in sustainable development because the blessings of free trade have associated with them (a) production pollution arising from the production process, (b) consumption pollution, which is the indirect effect of pollution produced by consumers in enjoying goods and services, and (c) negative impacts on the environment of the production process. Sustainable development cannot be achieved in a world where developed countries with higher technical skills for producing a wide range of technology selfishly focus on consumer goods and services instead of focusing on more basic improvements in using the world's resources to the benefit of the poor. Furthermore, sustainability cannot be achieved and inequalities eliminated through the trickle-down process from the developed countries unless the increasing ability to use resources more efficiently and to reduce waste and pollution is used to assist less fortunate people who cannot provide the minimum level of basic needs.

Liberalization and an increase in North-South trade and aid cooperation have not significantly contributed to equity and sustainable development, especially where the poor developing countries are tempted to exhaust their valuable natural reserves at lower prices in order to feed the trend-setting and unsustainable consumption patterns of the North in return for consumer goods and machinery. Such trade involves the depletion of natural resources by the sale of non-renewable minerals and harvests from soils, forests, and oceans, and the soils being increasingly used as the dumping sites of undesirable waste. Related to this is the fact that aid to developing countries to develop the same technologies that degrade the environment and cause the same pattern of polluting consumption as in the West cannot contribute to sustainable development.

Droste and Dogse (1991) observe that investments in education, science, and technology that contribute to human welfare and the decisions surrounding them are also often contributors to environmental problems. Examples include:

investments in short-term income-generating activities such as deforestation, intensive agriculture, and plantations, without concomitant investments in soil conservation and protection measures;

spending more money on combating pollution or on remedial measures than would be needed for preventive measures;

the use of subsidies, trade barriers, and various production technologies (including biotechnology) in the developed countries to produce surpluses that undermine the production of farmers in developing countries, making it difficult for the latter to compete or even ensure access to the inputs needed.

Constanza (1991) maintains that, to achieve global sustainability, it is necessary to switch from the concept of ecological and economic goals being in conflict, to one of economic systems being dependent on ecological life-support systems, and also to incorporate it into our thinking and actions at a very basic level. In other words, human beings must realize that:

(a) humans are only part of the subsystem in both local and global ecosystems;

(b) sustainability is a relationship between dynamic human economic systems and larger but normally slower-changing ecological systems in which human life can continue indefinitely, human cultures can develop, but the effects of human activities must remain within bounds, so as not to destroy the diversity, complexity, and function of the ecological life-support system.

It is necessary that the idea of economics being in conflict with ecology be replaced by one of the integration of conventional economics and conventional ecology into ecological economics, as shown in figure 7.1 and table 7.1. There is also a need to ensure continued adequate investment in natural capital and in finding ways of limiting physical growth so as to encourage development with an emphasis on qualitative improvement.

The above survey of the implications of sustainable development is necessary because it emphasizes that the problem is not mainly one of having a better definition of what sustainable development is. The main issue or critical factor is how to rehabilitate the natural resource base and repair the damage already done while not contributing to making things worse by continuing unsustainable living - locally, nationally, regionally, or globally. In this regard, it is also obvious that the greatest challenge is how to engender a transition that is steady, continuous, and on an even keel in all sectors at individual, community, national, regional, and global levels.

Driving forces

The problem of environmental degradation as a result of various development and other activities that constitute driving forces has to be understood as a basis for determining measures for ensuring sustainability. The driving forces considered here include:

modernization
agriculture, including livestock production and fishing
population explosion
fuelwood and energy management and associated deforestation
industrialization
poverty and affluence urbanization
other miscellaneous activities and phenomena.

Holdgren, Daily, and Ehrlich (1995) recently included among driving forces: excessive population growth; maldistribution of consumption and investment; misuse of technology; corruption and mismanagement; and powerlessness of the victims. The authors also refer to underlying human frailties such as: greed, selfishness, intolerance, and shortsightedness; and ignorance, stupidity, apathy, and denial. These are among the miscellaneous activities and phenomena listed above but only modernization is considered in detail here, although they are implied when it is stressed that, for sustainable development, changes are needed in attitudes, lifestyles, morals, ethics, behaviour, and philosophy.

Modernization

Modernization may be defined as a process of transformation of the way of life (culture, social and economic structures, and attitudes) from the characteristics of traditional societies to those dictated by changes brought about by industrialization, urbanization, trade, and communications. Of major importance in the modernization process is the West European influence, which was most pronounced during various periods of colonialism. This was followed by a period of political/ideological, technical, cultural, and other influences related to American/West European and East European aspects of modernization associated with the Cold War. With the end of communism, Westernization influences have become dominantly more American. However, it must be admitted that, just as with sustainable development, modernization has many interpretations. Its meanings and indicators range from its being equivalent to industrialization to a more complex process affecting all aspects of human life, with the indicators ranging from GNP, income, or number of cars per 100 people to combinations of major economic indicators ranging from life expectancy to numbers of scientists per 1,000 of population and quality of life indices. A few definitions of modernization are considered below to clarify the situation.

Todaro (1986) defines modernization as the transformations in attitudes, institutions, and ideologies that are associated with processes such as urbanization and industrialization, whose characteristic ideals include: rationality, which is the substitution of modern methods of thinking, acting, producing, distributing, and consuming for age-old traditional practices; planning or the search for a rational coordinated system of policy measures that can bring about and accelerate economic growth and development, with the plan period usually in units of five years; social and economic equalization aimed at promoting more equality or equity in status; improved institutions and attitudes, including changes that are deemed necessary to increase labour efficiency and diligence; the promotion of effective competition, social and economic mobility, and individual enterprise, raising living standards, changing outmoded land tenure systems, and changing educational and religious structures.

Hoogvelt (1982) defines modernization as a process by which developing countries were to be made either efficient producers and exporters of agricultural products and raw materials, or consumers of industrial products from the West, or both, thereby participating in world economic relations. Modernization started at the end of World War II in underdeveloped countries as a process in development activities regarded in liberal progressive circles as a necessary complement to the economic reconstruction in war-ravaged industrial countries and of a prosperous world capitalist economy based on free trade. In order to accomplish this goal rapidly, it was felt that fast changes from "stone age" to the twentieth century through the modernization process were necessary. According to the neo-evolutionary theory of development, modernization involved structural compatibility between certain primary consequences of modernization, consisting of advanced economic institutions (money markets, occupational specialization, profit maximization, etc.), and certain second-order consequences, consisting of Western "modern" political, social, and cultural institutions, with second-order institutions such as social mobility of individuals, nuclear family patterns, nationalism, formal education, a free press, voluntary associations, urbanization, and consumerism regarded as prerequisites for economic development. There was also some collusion of interests between Western international capitalism and the ruling elites of the new ax-colonial territories, who in many cases dictated the goal of development to be economic, involving the wholesale adoption of Western social, economic, and political structures. Traditional elements or counterparts of these consequences and characteristics of modernization, such as kinship and the extended family, were condemned as obstacles to development.

Until the second United Nations Development Decade, the above primary and secondary characteristics of modernization of the neo-evolutionary modernization theories led to the use of indicators for comparing developing countries that included such economic, political, and social factors as degree of urbanization, industrialization, political democracy, secularization, social mobility, occupational differentiation, free enterprise, and independent judiciary. The World Bank and other international organizations used these factors to outline the socio-economic programmes that contain these elements as a basis for qualifying for aid. Western technology, Western methods of production, and Western economic enterprises were also welcomed as vital agents of development.

Dube (1988) observes that, following World War II and the escalation of the number of independent countries, modernization was born as a new development paradigm. At that time, as new independent states launched massive economic development and technical change programmes aimed at getting them in a few years to where their erstwhile colonial rulers had taken centuries to reach, the developed countries were forced by conscience and humanitarian interest, in addition to strategic power interests and promise of long-term economic gain, to extend their cooperation in a limited way. Modernization emerged as one of the formulations of social scientists aimed at evolving stable patterns of relationship that were mutually beneficial, with prospects of short-term and long-term national interest weighing heavily on both developed and developing countries. In putting forward the theories of modernization, social scientists were determined not to offend the sensitivities of the new nations. "Modernization" was invented as a more acceptable term to replace "Westernization." Because of its academic respectability, funds flowed easily to research on this new paradigm, and aid was extended to programmes aimed at achieving it.

Dube (1988) also notes that modernity was understood to be a common behavioural system associated with the industrial, literate, and participant societies of Western Europe and North America. Developing countries were impressed by the varying degrees of success of the countries that early in the twentieth century joined the race for industrialization, such as Japan (the first Asian country to do so) and Russia. The basic underlying assumptions were that:

1. inanimate sources of power could be tapped with a view to solving human problems and ensuring minimum acceptable standards of living, the ceiling of which will rise progressively;

2. both industrial and collective efforts should be channelled to achieve this;

3. to create and run complex organizations, radical personality changes and attendant social structures and values were necessary.

As to the nature of modernization, it is regarded as a process very similar to development (see table 7.2). However, although many of the attributes of the two processes - such as their being revolutionary, complex, systematic, lengthy, and phased - are acceptable, others are open to question, including the following:

some of the benefits have been widely diffused but large sections of human society often remain unaffected;

the extent of their being global is debatable;

although the world is increasingly being described as a global village on account of homogenization, the rise of ethnicities and pluralities of culture is tearing it apart;

whether the process is irreversible remains to be seen - the rise of fundamentalism and what is happening in the Soviet Union indicate that it is not;

whether the processes are progressive remains a matter of opinion, with individual alienation and social anomalies occurring and collective violence increasing;

although the benefits are substantial, the social cost and cultural erosion (coupled with environmental degradation) are escalating.

There are several dilemmas associated with modernization and development:

there are inequalities in wealth and affluence, with many countries not attaining high growth rates of GNP;

many countries (developed or developing) face cycles of recession, severe inflation, and growing unemployment;

the rationality of the system is in question, with current gaps in access to resources among countries and between men and women;

there is increasing violence and crime;

corruption is a way of life in many places;

the lifestyles of the affluent in developed countries are taking hold in developing countries;

there is misdirection of science and technology and even funds for development to military and disharmonious pursuits;

although developed countries spend billions of dollars on tools of destruction, they cannot devote 1-2 per cent of their GNP to development in the developing countries;

developing countries spend millions on military hardware while millions of their people die of hunger;

the world's finite energy resources of coal, tar, petroleum, oil, natural gas, and uranium not only are unevenly distributed but are becoming exhausted, while the capabilities for generating alternatives and their sustainable use vary from one country to another;

non-fuel mineral resources are also running out, as well as being unequally distributed;

world forest resources are disappearing fast and rapid loss of bio-diversity is also taking place;

billions of tonnes of soil are being lost to erosion and vast areas of agriculture are being degraded;

increasing emissions of carbon dioxide and greenhouse gases are causing ozone depletion and climatic change.

Table 7.2 The similarities between modernization and development

Modernization Development
1. Revolutionary process with significant technological and cultural consequences, e.g. rural agrarian cultures being transformed into urban industrial cultures 1. Same
2. Complex and multidimensional process with series of cognitive, behavioural, and institutional modifications and restructuring 2. Same
3. Systematic process with variations in one dimension producing important co-variations in other dimensions 3. Same
4. Global process, with ideas spreading from one centre of origin to other parts of the world 4. Same
5. Lengthy process with no known way of producing it instantly 5. Same
6. Phased process that, according to experience, involves known phases and sub-phases, namely: 6. Same, namely:
(i) traditional (i) underdeveloped
(ii) transitional (ii) developing
(iii) modernized (iii) developed
7. Homogenizing process, with advanced stages significantly narrowing differences between national societies and ultimately reaching a stage when the universal imperative of modern ideas and institutions prevails, and various societies are so homogenized as to be capable of forming a world state 7. Same
8. Irreversible process, although there may be occasional upsets and temporary breakdowns 8. Same
9. Progressive process regarded as inevitable and desirable, ultimately contributing to human well being culturally and materially 9. Same
10. Painful process and in some instances in the past built on painful and ruthless exploitation of segmeets of society, dividing or integrating peoples, and resulting in privileged or underprivileged people 10. Same for areas that have been under colonial rule
11. Multilinear and multi-path process, with societies not necessarily all taking the same route but some times alternative paths 11. Same
12. Cannot be visualized as continuous or unending path since they are conditioned by outer and inner limits and human perceptions can change and have changed course 12. Same

Source: Adapted from Dube (1988).

Dube (1988) identifies several factors that obstruct modernization and observes that many nations are torn between their allegiance to tradition and a commitment to modernization. Several barriers to modernization of an ideological, motivational, institutional, and organizational nature are encountered, as well as problems of a decline of the paradigm, ambiguities and inadequacies, environmental constraints, and global problems.

Modernization and sustainable development in Africa

Modernization has associated with it several benefits, including: education and educational infrastructure; applications of science and technology in banishing ignorance and superstition; improved health and sanitation; improved communications; improved water supplies; improved nutrition; and employment and high incomes. Most of these consequences, except that of high incomes, are very likely to enhance sustainability in development.

There are also many changes associated with modernization that have adverse effects on sustainability in development. These include: increased dependence on the West for what Africans wear or how they think; the importation of inappropriate technologies; a change in standards associated with lack of appreciation of traditional things; unsustainable lifestyles; and acculturation stress owing to massive exposure to Western media and communication channels to an extent that Africans are unable to fight back. It is a paradox, for example, that improved health and medical services, better sanitation, a decline in infant mortality, and longer life expectancy, which are associated with modernization, are causes of rapid population growth and its obvious adverse environmental and socio-economic consequences.

Modernization has made deep inroads into African culture and has also caused changes in attitudes and overall changes in lifestyles that are not as sustainable as some traditional African ones. Increased dependence on Western or imported clothes, food, and drink results in loss of income and foreign exchange needed for development. The importation and use of excessive amounts of certain pesticides, chemicals, and inappropriate technologies result in damage to the environment. Some technologies, such as agricultural and forest logging machinery, can do serious damage to the soil and vegetation. The emergence of a global culture has adverse effects on the attitude of the youth towards traditional African culture and sense of standards. In African culture, work is appreciated and a farmer has status depending on his productivity. With modernization, farmers have lower status irrespective of their productivity. As a result of modernization, indigenous knowledge is not appreciated or utilized, yet, without a good understanding, knowledge, and appreciation of indigenous knowledge, traditional resource management strategies, and technologies, African research and development activities cannot develop production systems for the location-specific conditions in Africa. Exposure to the media has significant effects on Africans and not only causes the development of unsustainable attitudes and habits but also causes acculturation stresses.

Agriculture, livestock production, and other driving forces

Modernization has been given detailed treatment here because it has an all-pervading influence on all human sectoral development activities, attitudes, value systems, and way of life. The other driving forces are only briefly addressed because they are covered in greater detail elsewhere in this volume. A summary of the environmental impacts of these driving forces is presented in table 7.3. Reference to this indicates that population is a major driving force because its rapid growth exerts considerable pressure on resources, renders sustainable traditional farming systems outmoded and unsustainable, and contributes to the adverse effects of urbanization, scarcity-triggered deforestation, fuelwood management, etc.

At the same time, such forces as commercialization of agricultural production, related market forces, and, more recently, measures necessitated by structural adjustment (SAP) often also cause exploitative damage to the environment and the resource base.

Levels of environmental effects of human activities and sustainability concerns

The environmental impacts of development activities occur at the local, national, regional, and global levels. Concern about them also occurs at all levels but the magnitude of the adverse effects of certain activities may be more seriously felt at one level than at the others. Similarly, measures to be taken in dealing with the problems caused by adverse environmental impacts may be more effective if taken at one level than at another.

Table 7.3 Major driving forces and some of their main environmental impacts

Driving forces Some of the main environmental impacts
1. Agriculture, livestock production, fishing and hunting Under high population pressure and intensification of farming, traditional farming systems become out moded, causing land degradation including erosion.
  Increasing livestock numbers beyond carrying capacity also cause land degradation.
  Cash cropping can result in excessive deforestation, loss of biodiversity, and environmental pollution.
  Mechanical clearing and excessive tillage cause land degradation and erosion.
  Land degradation causes expansion of farming and grazing often into more marginal areas, resulting in more deforestation and land degradation.
  Deforestation and damage to vegetation cover in farming and grazing, in addition to unregulated fishing and hunting, result in rapid loss of biodiversity.
  Burning of vegetation in farming and pasture management produces greenhouse gases, which pollute the air, smoke, and suspended particulate matter.
  Ruminants produce methane, which pollutes the atmosphere.
  Intensification of farming without adequate fertilizer/manure application causes land degradation, while excessive use of fertilizers and pesticides also causes environmental pollution.
  Soil erosion and excessive runoff cause siltation of streams and rivers, with adverse effects on aquatic resources.
2. Population growth Rapid growth intensifies pressures on resources, resulting in excessive deforestation and environmenal degradation because sustainable traditional farming systems cannot cope.
  Population growth drastically reduces available land per capita, resulting in removal of all natural vegetation and loss of biodiversity of plants, animals, and micro-organisms. This either eliminates national parks and reserves or causes sharp declines in areas available.
  High population pressure on forestry and fishery resources also causes serious loss of biodiversity.
  Population concentration generates enormous amounts of waste, which pollutes the environment, while concentrations of livestock also degrade the environment.
3. Industrialization Some industrial technologies and processes cause atmospheric pollution, with greenhouse gases, acidrain, and loading of the air with suspended particulate matter.
  Undegraded plastic products produced by industry constitute a major environmental hazard.
  Industry produces enormous quantities of solid and liquid waste in addition to toxic chemicals, which pollute the environment. Some of these hazardous wastes in developed countries are transported to Africa.
  Industrial accidents (such as the one that occurred in Bhopal in India) endanger life and property in addition to destroying the environment.
4. Urbanization Urbanization causes climatic, hydrological, geomorphological, vegetational, and environmental quality changes.
  The production of large amounts of liquid and solid waste, in addition to contaminants, causes pollution of land, water bodies, and atmosphere.
  Urban transport produces greenhouse gases and smog.
  Urbanization increases flooding and lowers water quality and hydrological amenities.
  Urbanization increases crime rates and drug traffficking and breeds slums.
5. Fuelwood and energy management Over 80% of the energy in Sub-Saharan Africa comes from fuelwood and biomass.
  The collection of fuelwood and charcoal to satisfy this demand results in rapid rates of deforestation, which exacerbate the environmental degradation caused by forest clearing for agriculture, pastures, ranges, and other land uses.
  The making of charcoal and burning of fuelwood produce greenhouse gases and particulates that pollute the atmosphere and contribute to climate change and ozone depletion.
  The building of large dams for hydroelectric power results in eutrophication. Sedimentation behind dams for irrigation increases the incidence of parasitic waterborne diseases such as bilharzia, aquatic weed problems, etc.
6. Poverty and affluence The poor have limited access to resources and wreak havoc by exploiting the environment to the extent that there is rapid irreversible degradation.
  The poor, who cannot purchase inputs for farming, mine the soil, thereby causing land degradation.
  The poor cannot afford to provide sanitation services, with the result that land, water, and atmosphere are polluted.
  Affluence causes people to destroy the environment through the excessive use of chemicals and pesticides and the maintenance of unsustainable livelihoods.
7. Other miscellaneous activities and phenomena Examples of miscellaneous factors that also have adverse impacts on the environment include greed,
  excessive consumption patterns, war and social conflicts, etc., which result in environmental degradation and damage to life and property.

Local impacts

Certain effects of human or development activities may be highly localized. For example, if a whole tree falls in a tropical forest it knocks down or carries with it broken branches of surrounding vegetation or lianas and may smash and kill several small seedlings, herbs, and shrubs that are in its way. Within the damaged area, called the chablise, some light is allowed into the canopy. Within a short time most of the non-woody and succulent material decomposes and releases nutrients to the soil, from where they are recycled in a more or less closed cycle. Within a few years the chablise is covered by vegetation and there is no movement of materials outside the ecosystem. Similarly, a small clearing in the forest for shifting cultivation may have only a limited localized effect and even the gases produced in the slash and burn clearing do not travel very far away since the volume of the gases produced may be very small.

National and regional impacts

Most environmental effects that might attract attention or have impacts at the national level start in a small way locally and then gather momentum to become important at both national and international levels. For example, many river basins cut across several countries. According to UNEP (1992), the proportion of river basins in Africa that are international, out of a total of 56 river basins, is 26 per cent, compared with 22 per cent in Europe, 19 per cent in Asia, 17 per cent in South America, and 16 per cent in North and Central America. It is obvious that in such river basins as in the Niger and the Nile, development activities and natural disasters such as floods upstream may have trans-boundary effects along the river basin. Although small isolated forest fires have only local effects in Africa, during the dry season north or south of the equator fires in hundreds of small clearings produce smoke and gases that combine to contribute a considerable amount of greenhouse gases, which in turn gather momentum to have regional impacts. When they join jet streams in the upper atmosphere they may have global effects. It is obvious from this example that some of the environmental impacts, whether local or regional, are related to time. For example, whereas Africa's contribution to the global load of carbon dioxide and greenhouse gases constituted less than 100 million tonnes in 1900, by 1980 the CO2 released by burning fuelwood and by deforestation, which minimizes the sink capacity for CO2, amounted to about 700 million tonnes per year (see fig. 7.3).

The activities and impacts of tropical deforestation also occur at different levels. In fact, Wood (1990) observes that "at the local level deforestation primarily affects shifting cultivators and a growing population of rural peasants" but "the same problem multiplied over thousands of locations and combined with extensive logging can exacerbate the global issue of accelerated build-up of carbon dioxide." Wood (1990) likens the environmental politics of deforestation, consisting of four expanding layers of eco-political interaction at local, national, multilateral, and global levels, to the four sides of an upside-down pyramid (fig. 7.4). Each of the sides of this "upside down pyramid" -number of actors; number of political jurisdictions; complexity of ecological cause and effect relationships; and institutional obstacles to enforcement -represents an attribute of the deforestation problem that is compounded as it moves up the hierarchy. Thus deforestation not only becomes more complex ecologically as it moves from the local level to the global but also becomes more intransigent politically.


Fig. 7.3 Annual carbon release for the biomass system of the world's four major regions, 1900-1980 (Note: Whereas Africa's CO2 emissions from petroleum fuels in the 1980s were low - 0.25 tons/capita, equivalent to 8% of the figure for the United Kingdom - its CO2 emissions due to deforestation were about 700 million tons, or 1.5 tons/capita, at a time when such emissions were negligible or negative for European countries. Source: G. Leach, Agroforestry and the way out for Africa, in M. Suliman, ea., The Greenhouse Effect and Its Impact on Africa, London: Institute for African Alternatives, 1990)

A peculiar kind of trans-boundary environmental impact involves locally generated toxic waste in developed countries, which is transported across the seas to be deposited at minimum cost in some developing countries. This made it a global problem and the United Nations had to step in and formulate a convention to deal with such wastes.

Problem of transmission of cultural behaviour and standards at the international or global level

An aspect of modernization that could have very adverse effects on sustainability is the globalization of culture and economy that has exposed Africans and some indigenous peoples to advertisements via global television, video, radio, newspapers, and other media. Not only is it possible to advertise by television and radio, but fashion shows and behaviour patterns of people in Europe and America are projected to Africans in their own bedrooms, thereby making them interested in the material luxury consumption propensities of the North.


Fig. 7.4 Hierarchy of eco-political interactions in tropical deforestation (Source: Wood 1990)

Not only fashion but also criminal acts and lifestyles that are by no means sustainable are being "marketed" through the media. There is no doubt that the lack of strong cultural discipline in Africa as compared with Asia is one of the reasons that the level of savings in Africa is much lower than that in Asia. Although we have considered environmental impacts that start locally and gather momentum at the regional level to become global and affect millions of people physically, there is also a situation where people's attitudes and cultures are altered at the global level, and whereas certain global conventions have been passed to combat the former situation, it is not so easy to inculcate sustainable lifestyles or attitudes in the face of market forces and the globalization of culture that have become or are fast becoming deeply entrenched.

Constraints on sustainable development in Sub-Saharan Africa

Constraints on sustainable development in Sub-Saharan Africa are legion. Some are general and others are sectoral or specific. Some are local while others are national or regional. It must also be admitted that, prior to the adoption of the current sustainable development paradigm, Sub-Saharan Africa lagged behind other regions in food security, standard of living, and various aspects of development. Consequently, the adoption of a new development paradigm that places more emphasis on environmental resource conservation does not eliminate the existing constraints on development. Rather it requires more interdisciplinary or systems approaches, greater sensitivity to environment in policies, strategies, planning, and execution of development programmes, and stringency in defining the characteristics and nature of technologies that can be used to ensure the maintenance of environmental quality and the conservation of natural capital stock, which is imperative for sustainable development.

General constraints

The general constraints on sustainable development are political, socio-economic, and technological in nature.

Political constraints

THE COLONIAL LEGACY. At the time when explorers established contact with Africa and pushed further inland and developed a lucrative trade in spices, ivory, and forest products in exchange for alcohol and various manufactured goods, the prevailing development ideology in Europe was based on the Old Testament idea expressed in Genesis that God gave man "dominion over the fish of the sea, over the fowl of the air, and over every living thing that moveth upon the earth." Consequently, it was generally believed that humans had the right to exploit the natural resources of Africa and other parts of the world as desired. No serious effort was made to conserve natural resources until late in the eighteenth century when it was observed that with the extinction of the dodo in Mauritius it became necessary for measures to be taken to ensure the survival of diverse species of organisms through the establishment of reserves. The establishment of colonial spheres of influence and the arrival of Christianity, which in some areas preceded colonial administrations, dealt a death blow to the appreciation of even ecologically sound sustainable traditional or indigenous resource management strategies, practices, systems, attitudes, and behaviour patterns in African culture. This was most pronounced where these practices were applied as taboos associated with traditional African religion. It is not surprising, therefore, that taboos dealing with hunting and fishing were abolished outright and in agriculture such practices as intercropping were regarded as primitive. With colonialism came changes in the African perspective of looking at things, Westernization, and the propensity for consumption patterns of a more materialistic kind that are satisfied only with imports of food and manufactured goods, leading to increasing dependence on the developed countries.

POLITICAL INSTABILITY. NO sustainable development can be achieved in Sub-Saharan Africa with the kind of endemic political instability that has been the order of the day since independence in the 1960s. The instability is not unrelated to the artificial boundaries cutting across ethnic groups or groupings of incompatible people in the same country. Although inter-tribal wars were in existence before colonial administrations were established, there are indications that Europeans actually encouraged inter-tribal conflicts that supplied captives or prisoners to be sold in the slave trade. Moreover, the divide-andrule policies prior to independence often led to incompatibilities and unequal development among different areas or peoples lumped together in the same country. Coups and frequent changes in government have resulted in inconsistencies in policies and development programmes and a lack of continuity in development activities, all of which are incompatible with sustainable development. Figure 7.5 shows the extent of political instability in African countries, as indicated by the numbers of military regimes, by civil strife, and by stages in the democratization process.

CORRUPTION AND DEFICIENCIES IN GOVERNANCE. It has been indicated earlier that one aspect of modernization is the collusion between the elite or politicians in power in African countries with businessmen or agents of the former colonial powers and, in fact, other countries to ensure that certain development activities are executed in ways that are of mutual benefit to the individuals or businesses involved, often to the detriment of the common people in the African countries concerned. It is also well known that, while some African countries are unable to allocate funds to vital development projects, some of the politicians are busy stashing millions of dollars of ill-gotten money in Swiss banks or in investments in property in foreign countries. Related problems are a lack of accountability, waste, and a lack of grass-roots democratic institutions and participation in decision making. In the past, more emphasis was given to top-down approaches to extension work and development programme execution. It is only recently that emphasis is being given to bottom-up participatory approaches.


Fig. 7.5 Stage of democratization, civil stability, and economic status of African countries, October 1992 (Source: L 'Express, Paris, 8 October 1992))

DEFICIENCIES IN PLANNING. Sustainable development necessitates the adoption of holistic or systems approaches, which call for multidisciplinary interaction involving all relevant disciplines and ministries simultaneously working together in the planning process in an integrated manner. In sustainable development, environmental concerns are best integrated into the programme at the planning stage, when measures are taken to ensure the compatibility of all sectoral plans and the integration of environmental and developmental concerns at all stages. This necessitates special training and orientation of all concerned.

INAPPROPRIATE POLICIES AND STRATEGIES. Concern about the environment must be embodied in development policies and strategies. In other words, policies must be formulated in relation to the objectives to be achieved, and the strategies to be adopted must aim at a range of alternative strategy options that ensure conservation of resources and as far as possible enhancement of the quality of the resource base.

DEFICIENCIES IN LEGAL AND LEGISLATIVE SUPPORT OF DEVELOPMENT PROGRAMMES. There is need for economic incentives and legal and legislative instruments as a back-up for development projects in which maintenance of environmental quality and the conservation of resources are given high priority. Without such instruments, it would be difficult to ensure the achievement of resource conservation and environmental quality and to take the necessary measures to enforce compliance. In developing such legal and legislative instruments, it would be necessary to develop appropriate guidelines based on ecological and economic principles.

LACK OF EFFECTIVE REGIONAL INTEGRATION AND COLLABORATION ;IN DEVELOPMENT. Since the 1960s when many African countries became independent, all regional R&D organizations such as the CCTA (Commission for Technical Cooperation in Africa), EAFFRO (East African Freshwater Fisheries Research Organization), and related inter-territorial research organizations have broken down. Yet, with the small size of many countries, the limited resources available, the potentialities for sharing information, and experience and participation in R&D activities of mutual interest, there is no reason why African countries should be more strongly linked to their former colonial masters than to their African neighbours. This is the case not only in trade but sometimes also in the sharing and exchange of information on natural resources management and utilization. Even political and economic organizations such as OAU (Organization of African Unity), ECA (Economic Commission for Africa), and ECOWAS (Economic Community of West African States) rarely function as well as intended.

Socio-economic constraints

Socio-economic constraints on sustainable development include deficiencies in education and training, the lack of an effective campaign of public enlightenment and orientation, poverty, unfavourable economic conditions, and limitations in financial support.

Doubts continue to be expressed about the relevance of African education at all levels to the requirements of human resource and institutional capacity-building for innovative R&D in African countries. Sustainable development calls for environmental education at all levels and the development of appropriate curricula in science and technology embodying various aspects of natural resources conservation and management. The recommended ratio of 60:40 of students in science and technology to arts and humanities, respectively, in African schools and universities is rarely achieved at all levels in any African country. There are also deficiencies in the education of women, with the number of women at all levels far below the number of men, especially in the sciences.

With the change in development paradigm, there is a need for a public enlightenment campaign aimed at creating better awareness about sustainable development, what it is, what it entails, and the role of the masses in ushering it in sooner rather than later in Africa. Special training courses need to be developed in environmental monitoring, resources inventorying, and environmental impact assessment.

The prevailing poverty and adverse economic conditions in African countries owing to heavy debt burdens, unfavourable economic effects of structural adjustment, and two decades of continuing decline in commodity prices have left African countries with limited funds to maintain adequate levels of relevant R&D activities, to purchase, repair, and replace scientific equipment, as well as to acquire journals and literature in relevant scientific disciplines.

Technological constraints

Development involves the application of science and appropriate technologies to the conservation, management, processing, and rational utilization of natural resources. Since most African countries have neither the critical mass of trained personnel in many fields and at different levels, nor the institutional capacity for the generation and adaptation of technologies in order to make them appropriate for executing development programmes, self-reliance and success in development have eluded them. In the past, many development projects have been either disappointing or total failures owing to attempts at horizontal transfer of technologies and use of inappropriate technologies in location-specific situations. Moreover, because sustainability was not an explicit objective of development projects, no serious effort was made to choose and develop technologies that ensure economic viability, ecological soundness, and cultural acceptability.

Specific or sectoral constraints

In addition to the above general constraints on sustainable development, there are sectoral constraints on agriculture, including forestry and fisheries, industrial development, and mining.

Constraints on agriculture

The major constraints on sustainable agricultural production in tropical Africa are physico-chemical, biological, and socio-economic in nature. They are listed in table 7.4.

Constraints on industrial development

Constraints here are of three types, namely: environmental and natural resource constraints, technical and technological constraints, and socio-economic constraints.

The environmental and natural resource constraints include: high levels of environmental pollution and an inability or lack of means

Table 7.4 Constraints on agricultural production in tropical Africa

Physical constraints
Unfavourable climatic conditions include:
- rainfall that is unreliable in onset, duration, and intensity
- unpredictable periods of drought, floods, and environmental stresses
- reduced effective rainfall on sandy soils and steep slopes
- high soil temperature for some crops and biological processes (N-fixation)
- high rates of decomposition and low level of organic matter
- cloudiness and reduced photosynthetic efficiency
Most soils of the humid and subhumid tropics
- are intensely weathered, sandy, and low in clay
- have very low cation exchange capacity (CEC) and thus also less active colloidal complex
- have very low inherent fertility (except on hydromorphic and young volcanic soils)
- have very high acidity and sometimes high surface temperatures
- are extremely subject to multiple nutrient deficiencies and toxicities under continuous cultivation
- have very high P-fixation
- are extremely leached, and thus at high risk of erosion under prevailing rainstorms
- have serious salinity problems under poor irrigation management
Biological constraints
- unimproved crops and livestock
- low yields and low potential
- susceptibility to disease and pests
- high incidence of disease, pests, and weeds owing to environment that favours these phenomena
- drastic environmental changes, brought about by human activities that have adverse effects on ecological equilibrium
Socio-economic constraints
- small farm size, more drastically reduced by population pressure
- unfavourable land tenure systems, often resulting in fragmentation of holdings
- shortage of labour
- lack of credit and low income
- poor marketing facilities and pricing structure
- high cost and extreme scarcity of inputs
- poor extension services
- illiteracy and superstition, which sometimes hamper adoption process
- poor transportation
- inappropriateness of inputs
- lack of package approach to technology, development, and use

Source: Okigbo (1982).

for enforcing safety standards; dependence on imports for a substantial proportion of raw materials and equipment needed in industries; and limited allocation of resources for the conservation of natural capital stock and environmental protection.

Technological and technical constraints include: dependence on imported equipment, which often does not meet safety standards in the originating countries; lack of adequate capabilities for the maintenance and repair of equipment; deficiencies in human resources development, experience, and training; and limited research in promoting energy efficiency and the use of alternative energy resources.

Socio-economic constraints consist of: a lack of clear-cut industrial policies and strategies for sustainable development; high priority given to heavy industries at the expense of agricultural and light industries based on available renewable natural resources; high priority given to the achievement of rapid economic growth at the expense of environmental quality; limitations in industrial managerial experience; inability to monitor, control, and enforce environmental safety standards, and deficiencies in legal and economic instruments to support these; use of subsidies to promote practices that are environmentally degrading; the existence of poverty among large segments of the population, with markedly unequal distributions of wealth; and deficiencies in legal provisions for the protection of workers and for ensuring a safe and healthy work environment.

Constraints on mineral industry development

Constraints on sustainable development in the mining industry, as in industry, consist of environmental and resource constraints, technological and technical constraints, and socio-economic constraints.

Environmental and natural resource constraints consist of: a lack of adequate environmental safeguards to minimize environmental damage and degradation, especially in several sectoral development activities including road construction and open-cast mining; the fact that mining activities and practices sometimes cause gullies and considerable damage to the landscape and surrounding useful land; deficiencies in laws and regulations concerning the safety and protection of workers; considerable amounts of sediments and waste released into rivers and streams where they pollute the environment; limited provision for environmental rehabilitation of mined sites.

Technical and technological constraints may arise because mining, except for semi-precious stones, is often under the monopolistic control of multinational companies that conduct very little research and training in the host countries. The main constraints include: a lack of improved technologies for small-scale mining; limited endogenous capabilities for exploration and mining R&D activities; the monopolization by multinationals of information on reserves and characteristics of mineral resources; limited research on the rehabilitation and afforestation of mined sites; limited capabilities for attaining a reasonable level of minerals-based manufacturing to ensure the realization of the benefits of the value-added.

Socio-economic constraints include: deficiencies in policies that give multinationals control of relevant information on mineral resources; limited capabilities in mineral resource economics and the ecological economics of mineral resources; deficiencies in legal instruments; deficiencies in policy research; a lack of provision for the effective monitoring of environmental impact and the enforcement of regulations; frequent fluctuations in commodity market prices; and the social problems of female-headed households resulting from the migration of men to mines in southern Africa.

Recommendations

Sustainable development in Africa can be achieved only where appropriate policies, strategies, and priorities in research and development are carefully chosen and adhered to with the continuous commitment and allocation of resources and the creation of an enabling environment by governments. The elements of necessary ingredients for such sustainable development are briefly summarized below.

The adoption of a holistic or systems approach in planning, policies, and R&D

Sustainable development applies to the conservation, management, and rational utilization of natural resources in such a way as to maintain the integrity of each ecosystem, support all life, ensure no loss in biodiversity, and prevent environmental degradation. This calls for compatibility in sectoral development programmes in such a way that activities in any one sector do not have adverse environmental impacts, which would make it difficult to achieve the desired sustainable management of resources in any other sector now and in the future. For this to be successful it must involve the interaction of relevant disciplines in the planning and policy formulation stages, and in all stages of research and development (R&D) activities at local, national, regional, and global levels.

Conservation and development

There is need in all countries to adopt an environmental perspective in the management of natural resources in development programmes so as to ensure that conservation goes hand in hand with development in order to enhance sustainability. Conservation is defined as "the rational use of the earth's resources to achieve the highest quality of living for mankind" (UNESCO/FAO 1968), with the additional qualification that the quality of life also should apply to humans and to other organisms since this is the way to ensure conservation of biodiversity. When environmental quality is good for the survival of humans and other organisms then it is obvious that the environment is being given the due consideration it deserves in development if the earth is to function largely as a self-regulating planet.

Integration

Sustainable development calls for the adoption of a holistic and integrated approach in natural resource management. Opportunities for this exist in the following situations:

Land use

The adoption of an integrated land-use plan in which integrated watersheds as units for planning and development are a component entails the development of a master plan that provides for all the competing multiple land-use options, ranging from land for wildlife reserves and forest plantations to land for mining and human settlement, at least at national and regional levels.

Traditional and modern systems and technology

The integration of traditional, modern, and emerging resource management systems and technologies is one way of ensuring the relevance of technologies to the farmer's needs and circumstances, thereby facilitating rapid and widespread adoption. It involves the integration of desirable compatible elements of the different technologies in order to achieve sustainability. This approach also ensures that systems of production and their component technologies are ecologically sound, economically viable, and culturally acceptable.

Cropping systems and animal production systems

The integration of production systems involving, for example, the integration of arable (field) crop production with agro-forestry species in hedgerows and sometimes also with livestock into agrisilvopastoral systems can achieve a wider spectrum of objectives than can any of the systems alone.

Pest and disease management systems

Reliance on environment-polluting pesticides and chemical control in pest management can be minimized by mixing different strategies that interact synergistically to produce the desired effects. The combination of compatible chemical, biological, physical, and/or cultural methods in the control of pests and diseases aims to reduce reliance on any one method that, when used alone, may have adverse environmental effects - e.g. using a resistant variety and a few sprays of dilute chemical pesticide, instead of high concentrations and several sprays of more pesticides, which causes environmental pollution.

Species of crops and/or animals

Growing different species of crops or using different species of animals can ensure higher and more stable yields over time than growing only one commodity.

Alternative energy systems

It is necessary to develop alternative energy systems because reliance on fuelwood as the main energy source will not only lead to depletion of fuelwood resources and deforestation but also cause erosion and desertification.

Monitoring of resources and environment

For sustainable development to succeed, there must be monitoring of the status of various natural resources and analyses of the data in order to predict the likely consequences of environmental change in the future. Related to this is the inventorying of natural resources so as to determine changes in biodiversity causes and remedial measures.

Regulatory and guidance measures

Monitoring provides the basis for legislation and enforcement measures for protecting the environment. The results can also be used to guide actions to be taken or to enforce related laws and regulations.

Education, training, and orientation priorities

The existing educational curriculum needs to be modified so as to facilitate the provision of environmental education at different levels and the provision of training in environmental monitoring and assessment, in addition to orientation of the public so as to enhance popular participation in sustainable development projects. Any effort aimed at combating the development of inappropriate attitudes or standards as a result of the influence of the media can best be achieved through the educational system, formally or informally.

Other strategies

The above strategies are by no means exhaustive. It would be necessary to take appropriate measures to see that there are in place policies, strategies, technologies, systems, and other actions that are needed for combating or eliminating any of the constraints identified above.

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Sachs, I. 1973. Eco-development: A contribution to the definition of development styles for Latin America. United Nations Symposium on Population Resources and Environment, Stockholm, 26 September 5 October (E/CO NF 60/SYM -111/26, 18 September 1973).

---- 1992. Transition strategies for the 21st century. Nature and Resources 28(1): 4-17.

Serafy, S. el. 1991. Sustainability, income measurement and growth. In: R. Goodland, H. Daly, S. el Serafy, and B. von Droste (eds.), Environmentally Sustainable Economic Development: Building on Brundtland. Paris: UNESCO, pp. 59-70.

Tinbergen, J. and R. Hueting. 1991. GNP and market prices: Wrong signals for sustainable economic success that mask environmental destruction. In: R. Goodland, H. Daly, S. el Serafy, and B. von Droste (eds.), Environmentally Sustainable Economic Development Building on Brundtland. Paris: UNESCO, pp. 51 58.

Todaro, M. P.1986. Economic Development in the Third World. New York: Longman.

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(introduction...)

Introduction
Droughts in Sub-Saharan Africa and their implications for planning and development
Desertification
Land degradation and management of soil and water
Conclusion
Acknowledgements
References

 

Edouard G. Bonkoungou

Introduction

For Sub-Saharan Africa as a whole, consisting of 45 countries, gross national product per person in constant dollars fell by 20 per cent between 1977 and 1986. May (1988) reports that the average person in many of these countries is now poorer than at the time of independence about 30 years ago. Whereas Latin America and Asia have become almost self-sufficient in cereals, Africa has grown more dependent on imports and food aid. Total food production has, in fact, increased but not enough to keep pace with population growth. During the past 30 years agricultural production in Sub-Saharan Africa has risen by 2 per cent a year, while population is growing at the rate of about 3.2 per cent a year, faster than any other region has ever experienced (World Bank 1989).

The constraints on development in Sub-Saharan Africa are many and varied, including the following: a difficult climate with frequent episodes of severe drought in the semi-arid lands; fragile soils prone to erosion and nutrient depletion; a very fast rate of population growth; a heavy external debt burden. The world economy has not favoured Africa. Declines in Africa's commodity export prices and increases in the import prices of manufactured goods and oil have deteriorated the terms of trade and worsened Africa's external debt burden. Although this is true of all third world economies, the impasse in Sub-Saharan Africa is most striking.

Yet, as Harrison (1987) points out, the economic crisis is dwarfed by the continent's deepening environmental crisis. In the semi-arid regions, for example, recurrent droughts and population pressure have led to destruction of vegetation resulting in desertification, erosion, and depletion of soil fertility. Although the outlook is rather gloomy, there are individual projects that have succeeded against a background of general failure. If we could read the lessons of their successes, we might be able to piece together the formula, as Harrison (1987) puts it, and find some way of breaking through the development impasse.

This paper highlights some of the major environmental constraints in Sub-Saharan Africa and points to their implications for sustainable development strategies in the region, with a focus on semi-arid lands.

Droughts in Sub-Saharan Africa and their implications for planning and development

Recurrent droughts are a salient feature of the semi-arid lands of Sub-Saharan Africa, especially the Sahel. Rainfall fluctuates widely in time and space in a way that has not yet been understood and therefore cannot be easily forecast. The implication of this extreme variability for planning and development is that the concept of "mean" or "average" rainfall has little value.

Some of the main characteristics of the drought-prone climate of the region are presented below.

Rainfall fluctuation in time

The recent drought in the Sahel is not unique in the history of the region. Droughts of this magnitude and extent have occurred in the past. Nicholson (1982), using records of harvest quality, lake levels and river flow, rainfall data, and climatic description, reconstructed past episodes of droughts and good rainfall (see figs. 8.1 and 8.2).

For example, a wet episode lasted from about 1870 to 1895. Harvests were consistently good in the semi-arid regions of Namibia, southern Angola, and South Africa. North of the equator, the Niger Bend region near Timbuktoo, Mali, in the Sahel yielded abundant crops and the region became the "bread basket" of West Africa. Today, annual rainfall in the area is only about 200 mm, below the rain-fed agriculture boundary.


Fig. 8.1 Trends of African indicators of lake and river levels, rainfall, and harvest quality, 18801920 (Source: Nicholson 1982)


Fig. 8.2 Annual rainfall fluctuations in the Sahel, 1900-1982 (Source: Sircoulon 1992)

About 1895, a major change towards more arid conditions occurred and the "desiccation" culminated in severe drought around 19131914.

In more recent decades, rainfall was more abundant in the 1950s, with records as high as 30 to 60 per cent above "normal." But this episode ended abruptly towards the end of the 1960s, giving way to the extreme drought of the early 1970s when rainfall went down 15 to 35 per cent below normal in the Sahel. In some areas, rainfall during the 1968-1973 period was 50 per cent lower than during the 1950s.

Fluctuations are often abrupt and extreme, with droughts recurring at irregular intervals. The change from wetter conditions to persistent drought cannot as yet be forecast. Thus the implication for planning and development is that the carrying capacity of the land should be that of the driest years, not the "average" year.

Clustering and persistence of abnormal years

An unusual feature of rainfall fluctuations in the region is their extreme persistence for one to two decades or more.

In most humid areas, dry and wet years are generally randomly interspersed. In some arid regions, however, abnormal years tend to cluster together. In the Sahel, this characteristic is extreme: wet or dry conditions may persist for one or two decades. As an example, the period 1960-1980 was rather consistently dry. Droughts lasting one or two decades are also evident in the historical records mentioned earlier.

A study by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT 1988) illustrates this feature. Change in rainfall variability in semi-arid lands in India and the Sahel was compared by analysing long-term climatic records for Niamey in Niger and Hyderabad in India. The variability in annual rainfall at the two locations is shown in figure 8.3. In 87 years (1901-1987) at Hyderabad, the time-series showed no significant trend, and the rainfall in a given year is not correlated with that of the preceding or the following years. At Niamey in the Sahel, variability of annual rainfall from 1905 to 1987 revealed a different pattern. Compared with Hyderabad, Niamey has longer sequences of consecutive "dry" years with below-average rainfall, and much fewer "wet" years. Droughts are longer in the Sahelian zone.

The clustering of abnormal ("wet" or "dry") years seems to be unique to the Sahel. Other semi-arid lands in Africa do not exhibit this characteristic. Comparison of climatic data between the Kalahari region in southern Africa and the Sahel showed that, although drier (and wetter) periods tend to occur synchronously in both areas, the decadal persistence observed in the Sahel is not a distinct feature of rainfall fluctuation in the semi-arid lands of southern Africa; dry episodes coincide in the two regions but the years of most intense drought do not (Nicholson 1982). Although the recurrence of drought has been shown to be cyclic in some semi-arid regions, this has not been clearly established for the West African Sahel.

Spatial variability

High spatial variability is a well-known characteristic of Sahelian rainfall (figs. 8.4 and 8.5). The reason for this spotty distribution is the convective nature of the rains, i.e. the showery type, as shown in figure 8.6; the falling of rain from a cloud generally signals the onset of dissipation of the cloud, which may grow again and produce intense rainfall further away.


Fig. 8.3 Variability in annual rainfall in Niamey, Niger, and Hyderabad, India (Source: ICRISAT 1988)

Implications for planning and development

The implication of this extreme spottiness for regional planning is frightening. Two villages only 1 km apart can experience entirely different rainfall regimes at one time or another during the season, even during a year when total rainfall is comparable in both locations. For a given rainstorm, one village may be drenched while its neighbour remains dry. If this happens at a crucial time for crop development - e.g. when seedlings are establishing themselves or grain is maturing - this can mean a good harvest for one village and total crop failure for its neighbour.


Fig. 8.4 Spatial variability of rainfall on 12 and 13 June 1986 in Ouagadougou, Burkina Faso (Source: Rochette 1989)

Other features of the Sahelian climate described earlier pose equally serious constraints for planning. Persistent years of aboveaverage rainfall can create a false sense of the true climatic conditions and mislead farmers and pastoralists to extend their activities into the marginal desert fringe beyond the true agronomic dry boundary. They may then become trapped in this fragile environment during a drier period; the environmental damage that then occurs is intensified. This may have contributed to the disaster accompanying the droughts of the 1970s, which succeeded a very "wet" period in the 1950s.

As Nicholson (1982) summed it up, the characteristics of the Sahelian climate that should be kept in mind include the low and highly variable rainfall, the prevalence of dry years, the extreme magnitude of the variability, the rapidity with which new persistent conditions can be established, and the spottiness of rainfall even in "normal" years. The "persistence" feature of the Sahelian climate is a clear message to planners that technologies and strategies that have produced good results in other semi-arid regions of the world may not be expected necessarily to work in the Sahel.


Fig. 8.5 Spatial variability of rainfall shown as isoheyets measured on a 400 m grid over 500 ha at the research station of the ICRISAT Sahelian Centre, Niger, 22 July 1986 (Source: ICRISAT 1988)

The task ahead is immense. A complete understanding of the climatic peculiarities of the semi-arid lands of Sub-Saharan Africa and the tuning of development planning to these characteristics deserve sustained efforts. On-going programmes/projects and recent initiatives in this direction include those by the Regional AgrometeorologicalHydrological Centre, the Sahelian Centre of ICRISAT, the African Centre of Meteorological Applications for Development, the Sahara and Sahel Observatory, and the International Geosphere-Biosphere Programme in the region. This development is encouraging, but a breakthrough is still awaited.


Fig. 8.6 Continual growth and decay of a typical convective cloud as it moves downstream with the wind (Source: Nicholson 1982)

Desertification

The problem

Pressures from human and livestock populations coupled with the effect of recurrent drought have led to serious degradation of vegetation cover, erosion, and depletion of soil fertility on a large scale in many parts of Sub-Saharan Africa. Desertification, as this tragic land degradation is referred to, threatens the drylands of Sub-Saharan Africa in a larger proportion than any other region in the world. Once the vegetation cover is removed, the fragile soils are exposed to winds and battering rains. Erosion is inevitable. Early storms are often accompanied by strong winds. Wind speeds exceeding 100 km/hour have been recorded at ICRISAT Sahelian Centre in Niger. Blowing sand subjects seedlings to abrasion and often results in their being completely covered by sand, causing serious problems in crop establishment (Kalij and Hoogmoed 1993). In many areas this takes dramatic forms: shifting sand dunes that swamp villages and fields, formation of deep gullies, crusts that seal the soil surface and markedly increase runoff.

Desertification has been described as self-propagating (Harrison 1987): as expanding areas become useless for crops or livestock, the pressure on the islands of remaining fertility increases. Farming is taken beyond the limits of sustainable rain-fed agriculture. Whole families, sometimes whole villages, migrate to better-watered areas. There they begin the process of deforestation, overcultivation, and overgrazing anew.

Implications for development

The traditional solution

Over the centuries African pastoralists and farmers had developed efficient systems of land use compatible with their environment. For example, nomadic pastoralists traditionally moved with herds of animals to different areas of good grazing and water supply. With low stocking levels they were able to move to new areas before the reserves of any single area were depleted and the soil laid bare.

The parkland system of cropping under tree cover, a widely practised farming system in the Sahel, is probably the most elaborate traditional agro-forestry practice known today in any of the semi-arid zones of the world. In most instances, however, farmers have relied on natural processes for the regeneration of the woody component.

The current level of population pressure, however, precludes true nomadic grazing or passive reliance on natural regeneration to maintain adequate tree densities in the farmlands. Many of the traditional solutions are no longer viable. The severity of land degradation alerted the governments and the international community and led to the creation in 1973 of CILSS (Comite Permanent Inter-Etats de Lutte contre la Secheresse dans le Sahel). Major efforts by the international community to combat desertification include the 1977 UN Conference on Desertification in Nairobi, Kenya, the creation of the United Nations Sudano-Sahelian Office, and the agreement at the Rio Summit in 1992 to negotiate a convention on desertification. The agreement commits governments, relevant non-governmental organizations, and the scientific community to prepare and adopt an international convention to combat desertification in all affected areas of the world, particularly in Africa.

Technical interventions introduced so far to combat desertification have met with very limited success. Some of the reasons for this debacle include the misunderstanding of the nature of the problem, which was initially conceived solely as the responsibility of the government departments in charge of forestry; hence, the overemphasis on planting fast-growing species in woodlots and green belts. The failure properly to diagnose people's perception of the problem and to identify the felt needs of local populations fuelled antagonistic relationships between foresters and peasants. This was because modern forestry, contrary to traditional wisdom in the region, has been considered to be separate from agriculture and livestock. Harrison (1987) noted that "foresters viewed farmers and herders as vandals, destroyers of forests to be kept out at all costs. Peasants saw foresters as policemen who excluded them from land that was traditionally theirs to control and use. Under such conditions the forests did not flourish." I have expressed similar views elsewhere (Bonkoungou 1985, 1987, and 1990) and pointed out the risk of some foresters failing to see the people for the forest.

The situation described above explains many of the failures in the fight against desertification. Yet trees and shrubs have a crucial role to play in the future of farming and pastoralism in Africa, as is becoming convincingly clear from research results of the International Centre for Research in Agroforestry (ICRAF).

The potential of agro-forestry to combat desertification and sustain agricultural production

Baumer (1987) extensively discusses the potential of agro-forestry to combat desertification. As mentioned above, research results from ICRAF indicate that agro-forestry has great potential for mitigating tropical deforestation, land depletion, and rural poverty. Trees integrated with crops or livestock meet wider needs than do woodlots. If properly spaced and managed, they serve as windbreaks and shelterbelts. They mark boundaries and strengthen terraces. They supply not only fuel, timber, stakes, and poles but also cash crops, fodder, fruits, nuts, leaves, and pods for human and livestock feed, gums, and medicines. In addition to the above products and many others, trees and shrubs also render various services in environmental protection: shade, improvement of soil fertility, etc.

As Harrison (1987) so ably advocates, agro-forestry offers by far the speediest road to reforesting Africa. Many African farmers already practice one form or another of agro-forestry but have relied mostly on natural regeneration of woody species, which is no longer reliable because of the much-shortened fallow periods. The task ahead then, as Harrison (1987) puts it, is "to convert African farmers and herders from passive to active agroforesters; from users of selfplanted trees, to tree farmers."

ICRAF does just that. Established in 1978, with headquarters in Nairobi, Kenya, ICRAF implements research jointly with national institutions through networks associated with the major eco-regions. One such network, the agro-forestry research network for the SemiArid Lowlands of West Africa was launched in 1989 with the objective of generating appropriate agro-forestry technologies for the ecoregion and strengthening national agro-forestry research capabilities in the subregion.

Land degradation and management of soil and water

The problem

From the discussion presented above on drought and desertification, it is apparent that the fragile soils of semi-arias lands of Sub-Saharan Africa are exposed to increasing threats of wind and runoff erosion. It is also evident that water is a scarce, high-value economic resource in the region. In addition to high rates of evaporation, because the rains usually come during the hot period of the year, other major routes of water loss include soil evaporation and runoff owing to poor infiltration in the soil. Rains in the semi-arid lands of Sub-Saharan Africa do not fall gently and evenly; they come predominantly in convective storms as described earlier. Rain that falls this way in torrents is more destructive than the gentler rain of temperate zones. More is lost in runoff and less filters into the ground.

Yet water management is less advanced in Sub-Saharan Africa than in any other developing region, including Africa north of the Sahara where water management is more developed. In Sub-Saharan Africa, almost half of the irrigated area is concentrated in two countries only: the Sudan and Madagascar. In the rest of the region, irrigated land is only about 2 per cent of the cultivated area. This compares with 8.5 per cent in Latin America and 29 per cent in Asia (Harrison 1987).

Most of the large-scale irrigation schemes and soil conservation work tried out in Sub-Saharan Africa in the past have met with little success. As Critchley (1991) points out, concern about soil conservation is nothing new in Africa. Several colonial administrations recognized from the early part of the twentieth century that there was an erosion problem. Programmes of one sort or another continued in most countries until independence. But the majority of these schemes were resented by the local people, who were forced to supply labour.

However, the cycles of drought that have affected Sub-Saharan Africa in recent decades have drawn renewed attention to the role of soil and water management in ensuring crop production in semi-arid lands. The need for conservation programmes is much greater now, because of population increase, than when the first unpopular programmes were started. However, new approaches need to be developed to avoid the many mistakes of the past.

The way ahead: How to make every drop count

At least two major lessons can be learnt from past failures (Critchley 1991): first, for subsistence farmers, the idea of preventing future loss of soil is irrelevant to present pressing needs; and, secondly, the farmers themselves have, in the past, simply not been consulted about their knowledge and understanding of the processes of erosion. Both traditional technologies and social organizations have usually been ignored.

The way ahead calls for alternative strategies to large-scale conventional irrigation schemes or soil and water conservation projects. One such alternative being implemented with success in the Sahel is a low-cost water-harvesting technique adapted by incorporating a traditional practice, in Burkina Faso, of placing lines of stones to slow down runoff. But slopes in the Yatenga region where the project was developed are too gentle (between 0.5 and 2 per cent) and levels are impossible to get right by eye, although runoff erosion is quite severe. In response to this constraint, the Oxfam project devised an inexpensive (and rather ingenious) tool: the water-tube level, which accurately identifies the contour lines. Originally developed in the arid Negev desert 3,000-4,000 years ago, the water-harvesting technique is now being tried out with various adaptations in many parts of the Sahel, and is now widely adopted by farmers in the Yatenga region in Burkina Faso (Wright and Bonkoungou 1985; Younger and Bonkoungou 1989; Critchley 1991). The success of the technique has exceeded expectations.

In the course of four to five years, the Oxfam project perfected a traditional technique into a now highly valued water-harvesting technology that successfully collects water and holds it on the field, preventing soil erosion and increasing water infiltration and crop yields. Thousands of farmers now use the technique, and the number is growing rapidly as others observe its success. Scientists are now studying the possibility of using agro-forestry technologies to improve the technique even further by planting suitable trees and shrubs along the contour lines.

Supplementary irrigation and rain harvesting are a useful way to increase the water available to crops. However, Cooper and Gregory (1987) indicate that this is only one of many ways to make every drop count. They point out that in rain-fed farming systems, where lack of moisture limits crop production, agronomists frequently assess innovative management practices in terms of water use efficiency, which is the ratio of dry matter produced to water used for the production of that dry matter. This is expressed in units of kg/ha/mm and can be increased either by increasing total water supply, as in the case of the water-harvesting technique described above, but also by increasing transpiration efficiency or by reducing evaporation from the soil surface, e.g. through mulching. In terms of water conservation, the principal effect of mulching is to reduce soil evaporation. This is often complemented by many other beneficial effects. In the acid sandy soils (Psammentic Paleustalfs) of the Sahelian zone in West Africa, Kretzschmar et al. (1991) report that crop residues play a key role in increasing pearl millet (Pennisetum glaucum L.) yield, a beneficial effect likely due to improvement of P nutrition through both an increase in P mobility in the soil and enhancement of root growth. Although alternative uses of crop residues for fuel and animal feed limit their availability as mulch, the development of agroforestry techniques could make leaves and small branches of multipurpose trees available for mulching, a traditional practice known to small farmers in the rain-fed agriculture region of the West African Sahel.

The success of the water-harvesting technique demonstrates that a project that proceeds with a low budget and pursues a low-technology method can yield significant returns. Of course, this does not imply that all agricultural research should follow such a strategy - many high-technology projects have also yielded high rates of return - but it does suggest that a place exists for simpler technological changes, and that planners should not forget them. Small-scale measures on a large scale could be a viable alternative to the large-scale projects that so conspicuously failed in the past.

Conclusion

"Sustainability" and "sustainable development" have become the key terms in addressing the world's general concern over environment and development issues. In Sub-Saharan Africa, the development process seems to have reached an impasse. Food production per person has declined steadily during the past three decades. People in many countries of the region are poorer now than they were 30 years ago around the period of independence. The environmental crisis is equally tragic and plagued by desertification and recurrent droughts in the semi-arid lands and high rates of deforestation in the humid eco-zones.

Scattered in the gloomy picture, however, some success stories offer useful lessons and point to the direction that could lead to sustainable development in Sub-Saharan Africa. This paper has underlined the potential of agro-forestry and a small-scale water-harvesting technique to combat desertification and promote sustainable agricultural production. These alone would not be enough to reverse the current negative economic growth of Sub-Saharan Africa. Without them, however, it appears that sustainable agricultural development in the region could remain an insurmountable challenge for the near future.

Acknowledgements

I gratefully acknowledge the help received from Dr. Peter Cooper and Chin Ong at ICRAF, Dr. Joseph Menyonga at OAU/STRC-SAFGRAD in Ouagadougou, and Professor Bakhit, University of Khartoum.

References

Baumer, M. 1987. Agroforesterie et Desertification. ICRAF/CTA.

Bonkoungou, E. G. 1985. Forestry research in the Sahel: Process and priorities. Rural Africana 23/24.

---- 1987. Management of natural forest versus afforestation in the Sahel region of Africa. Future prospects. In: San Jose and R. Montes (eds.), La Capacidad Bioproductiva de Sabanas. Caracas, Venezuela: Centro Internacional de Ecologia Tropical, pp. 489 512.

---- 1990. Problematique des forets et de la foresterie en zones seches tropicales. Bilan et perspectives. In: IUFRO XIX World Congress Report B. Montreal, Canada, pp. 54 73.

Cooper, P. and P. J. Gregory. 1987. Soil water management in the rain-fed farming systems of the Mediterranean region. Soil Use and Management 3(2): 57 62.

Critchley, W. 1991. Looking after Our Land. New Approaches to Soil and Water Conservation in Dryland Africa. Oxford: Oxfam Publications.

Harrison, P. 1987. The Greening of Africa -- Breaking Through in the Battle for Land and Food. London: Paladin Grafton Books.

ICRISAT (International Crops Research Institute for the Semi-Arid Tropics). 1988. ICRISAT Annual Report 1987. Patancheru, India.

Kalij, M. C. and W. B. Hoogmoed. 1993. Soil management for crop production in the West African Sahel. II. Emergence, establishment, and yield of pearl millet. Soil and Tillage Research 25: 301-315.

Kretzschmar, R. M., H. Hafner, A. Bationo, and H. Marschner. 1991. Long- and short-term effects of crop residues on aluminum toxicity, phosphorus availability and growth of pearl millet in an acid sandy soil. Plant and Soil 136(2): Z15 233.

May, D. H. 1988. Africa Heading for Tomorrow. A Bretton Woods Committee Special Report on Economic Reform in Sub-Saharan Africa. Washington D.C.: Bretton Woods Committee.

Nicholson, S. E. 1982. The Sahel: A Climatic Perspective. CILSS/OECD.

Rochette, R. M. (ed.) 1989. Le Sahel en Lutte Contre la Desertification. Les d'Experiences. Berlin: CILSS/PAC.

Sircoulon, J. 1992. Le reseau pluviometrique en Afrique de l'Ouest. In: S. Janicot and B. Fontaine (eds.), La Variabilite Climatique en Afrique de ['Quest. Paris: Ministere de la Recherche et de la Technologie.

World Bank. 1989. Sub-Saharan Africa from Crisis to Sustainable Growth. A LongTerm Perspective Study. Washington D.C.: The World Bank.

Wright, P. and E. G. Bonkoungou. 1985. Soil and water conservation as a starting point for rural forestry: The Oxfam project in Ouahigouya, Burkina Faso. Rural Africana 23/24.

Younger, S. D. and E. G. Bonkoungou. 1989. Burkina Faso: The Projet AgroForestier. A case study of agricultural research and extension. In: Successful Development in Africa. Case Studies of Projects, Programs and Policies. Washington D.C.: World Bank, pp. 11 26.

(introduction...)

Introduction
TRF and its conversion
Soils of the TRF ecosystem
Forest conversion and soil productivity
Deforestation and the emission of radiatively active gases
Deforestation and hydrological balance
Sustainable use of the TRF ecosystem
Research needs
References

 

Rattan Lal

Introduction

The humid tropics comprise about 31 per cent of all tropical biomes, cover 11 per cent of the earth's total surface, occupy about 1.5 billion ha of land area, and are home to about 2 billion people (WRI 199091). Of the 1.5 billion ha of the humid tropics, 45 per cent lie in the Americas, 30 per cent in Africa, and 25 per cent in Asia and Oceania. Within the generic term "tropical rain forest" (TRF), there are three principal types of forest vegetation including: lowland rain forest (80 per cent of the humid tropical vegetation), premontane forest (10 per cent), and lower montane and montane forests (10 per cent). The TRF ecosystems are characterized by constantly high temperatures and relative humidity, high annual precipitation, highly weathered and leached soils of low chemical fertility, and high total biomass. High total biomass production, despite low soil fertility, is due to the effect of high temperatures and relative humidity, abundant rainfall, and low moisture deficit. The natural vegetation of the TRF is characterized by a high degree of biodiversity. The TRF ecosystem has global importance in terms of soil and climatic interactions and its impact on several processes. For example, local and global climatic patterns are influenced by the interaction of the TRF with the atmosphere (Salati et al. 1983; Myers 1989; Houghton 1990). An important aspect with global influences involves the impact of the TRF on biogeophysical cycles, e.g. C, N, S, and H2O. Conversion of the TRF to other land use disrupts these cycles, which are critical in regulating several global processes; e.g. emission of radiatively active gases into the atmosphere, change in the total water vapour present in the atmosphere. It is because of these local, regional, and global interactions that the TRF and its conversion are a major concern.

TRF and its conversion

In prehistoric times, the geographical area of undisturbed TRF was about 1.5 billion ha. It is estimated that 45 per cent of the original TRF has been converted to other land uses, with a regional loss of about 52 per cent in Africa, 42 per cent in Asia, and 37 per cent in Latin America (Richards 1991). Because of the wide diversity in vegetation type and in the mode and degree of conversion, however, there is a large variation in the estimates of the extent of the remaining TRF and rates of its conversion. The areal extent of TRF from 1700 to 1990 for three regions is depicted in table 9.1. Over the 290 years, the TRF decreased by 36 per cent in tropical Africa, 26 per cent in Latin America, and 30 per cent in Asia. The most drastic conversion happened between 1920 and 1950. The data in table 9.2 are an estimate of the total deforestation that occurred in different regions over a 328-year period. Low and high estimates of total forest conversion range from 484 million ha (32 per cent of the total) to 538 million ha (36 per cent of the total).

Present estimates of the remaining area of tropical rain forest and annual rates of deforestation are also highly variable and erratic (Myers 1991). Estimates of the total area of TRF for the year 1990 range from 1,282 million ha (FAO) to 1,715 million ha (WRI) (table 9.3). The principal discrepancy in the data in table 9.3 lies in the estimate of TRF for Africa. The WRI estimate of 600 million ha includes both closed forest and wooded areas. There are several categories of vegetation called TRF. These include closed forest, forest land, woodland, shrub land, forest land under shifting cultivation, and miscellaneous land (FAO 1981). The closed forest is the true TRF. The distinction between these categories is difficult to make, and estimates vary widely. Estimates of the area of closed forest and wooded land and the rate of conversion are shown in table 9.4.

Table 9.1 Global change in tropical rain forest and woodland, 1700-1990 (million ha)

Region 1700 1850 1920 1950 1980 1990 Total change
Tropical Africa 1,358 1,336 1,275 1,188 1,074 869 - 489
Latin America 1,445 1,420 1,369 1,273 1,151 1,067 - 378
South & South-East Asia 558 569 536 493 415 410 - 178

Sources: Richards (1991); WRI (1990).

Table 9.2 Esffmated area of deforestation, 1650-1978 ('000 km2)

Region Levela Pre-1650 1650-1749 1750-1849 1850-1978 Total deforestation 1650-1978
            High Low
Central America H 18 30 40 200 288  
  L 12         282
Latin America H 18   170 637 925  
  L 12 100       919
Oceania H 6 6 6 362 380  
  L 2 4 -     368
Asia H 974 216 606 1,220 3,016  
  L 640 176 596     2,632
Africa H 226 80 -16 469 759  
  L 96 24 42     631
Total H 1,242 432 806 2,888 5,368  
  L 762 334 848     4,832

Source: Williams (1991). a. H = high estimate; L = low estimate.

Table 9.3 Present estimates of TRF and the annual rate of deforestation

Region

WRI (1992 93)

FAO (1991)

  Total area Annual rate Total area Annual rate
  (ha m.) (%) (ha m.) (%)
Africa 600.1a 5.0 241.8 4.8
Latin America 839.9 8.3 753.0 7.3
Asia 274.9 3.6 287.5 4.7
Total 1,714.9 16.9 1,282.3 16.8

a. Includes wooded land area and closed forest.

Table 9.4 Different categones of TRF and their conversion rate

Region

Total area (ha m.)

Conversion rate (ha m./yr)

  Closed forest Wooded land Closed forest Wooded land
Africa 217 652 1.33 2.34
Latin America 679 388 4.12 1.27
Asia 306 104 1.82 0.19
Total 1,202 1,144 7.27 3.81

Source: WRI (1988 89).

There are several problems with the available data. Original data based on recent and direct surveys are not available. Most estimates are 10-20 years old and obsolete. Furthermore, there are differences in the criteria used, and the accuracy of most estimates is questionable. As with the area, the rate of deforestation is also hard to estimate. However, reliable estimates of the areas of TRF and rate of conversion are needed for: (i) land-use planning, and (ii) predicting the impact of forest conversion on soil and environment.

Soils of the TRF ecosystem

The predominant soils of the humid tropics are oxisols, ultisols, and alfisols (table 9.5). Oxisols and ultisols comprise 63 per cent of soils of the TRF (table 9.6). These soils are highly weathered, leached, devoid of basic cations, and relatively infertile. Young soils of moderate to high fertility (mollisols, inceptisols, and entisols) occupy about 15 per cent of the total land area. There are several soil-related constraints on intensive food crop production in the humid tropics. The principal constraints are listed in table 9.7. Oxisols and ultisols have low nutrient reserves and are prone to toxicity owing to high concentrations of Al and Mn. In general, these soils have high P-fixation capacity. Alfisols are relatively more fertile than oxisols and ultisols. However, alfisols have weakly developed structure and are highly prone to accelerated soil erosion. The effective rooting depth for food crops and annuals is generally 20-30 cm owing to either physical (compacted, concretionary, or gravelly subsoil) or chemical (Al or Mn toxicity, low P) limitations. Coupled with low plant-available water reserves, water deficiency can be a problem for shallow-rooted annuals. In contrast, upland crops can be subjected to periodic inundation and anaerobiosis. With proper management, however, the agricultural productivity of these soils can be greatly improved while minimizing risks of soil and environmental degradation. An impor tent strategy in enhancing the productive potential of these soils is to reduce the adverse effects of forest conversion.

Table 9.5 Geographical extent and distribution of major soils of the humid tropics (ha million)

Soil type

Region

  America Africa Asia Total
Oxisols 332 179 14 525
Ultisols 213 69 131 413
Inceptisolsa 61 75 90 226
Entisolsb 31 91 90 212
Alfisols 18 20 15 53
Histosols   4 23 27
Spodosols 10 3 6 19
Mollisols - - 7 7
Vertisols 1 2 2 5
Aridisols - 1 1 2
Total 666 444 379 1,489

Source: N RC (1993).
a. Inceptisols include Aquepts, Tropepts, Andepts, and Entisols.
b. Entisols include Fluvents, Psamments, and Lithic Entisols.

Table 9.6 Soils of the humid tropics (% of the total area)

Principal feature Soil type

Region

    America Africa Asia Total
Acid, infertile Oxisols and ultisols 82 56 38 63
Moderately fertile, & well-drained Alfisols, vertisols, mollisols,inceptisols, andisols, fluvents 7 12 33 15
Poorly drained Aquepts 6 12 6 8
Very infertile, sandy Psamments, spodosols 2 16 6 7
Shallow Lithic entisols 3 3 10 5
Organic Histosols - 1 6 2
    100 100 100 100

Source: NRC (1982).

Table 9.7 Soil-related constraints on intensive land use for food crop production in the TRF ecosystem

Constraint Oxisols Ultisols Alfisols Inceptisols Mollisols Andisols
Physical
Accelerated erosion 2 2 3 2 1 1
Soil compaction & crusting 2 2 3 2 1 1
Root impedance 3 3 3 1 1 1
Moisture imbalance 2 2 3 1 1 1
Shallow depth 2 2 3 1 1 1
Nutritional            
N deficiency 3 3 2 2 1 1
P deficiency 3 3 2 1 1 1
Al & Mn toxicity 3 3 1 1 1 1
Micro-nutrient deficiency 3 3 2 1 1 1
Biological
Soil fauna 2 2 2 1 1 1
Biomass carbon 2 2 2 1 1 1

3 = severe; 2 = moderate; 1 = slight.

Forest conversion and soil productivity

Deforestation and conversion to arable land use have drastic impacts on soil properties, water and energy balance, and soil erosion hazard (Lal 1987). The worst-case-scenario local effects are outlined in table 9.8. The principal soil degradation effects include adverse effects on soil structure leading to crusting, compaction, and hardsetting. Reduction in infiltration, increase in surface runoff, and soil exposure to raindrop impact and to the shearing effect of overland flow accentuate soil erosion risks. Alterations in pore size distribution and reduction in the colloid content of the surface soil, owing to eluviation, and preferential removal of clay and organic carbon by erosion drastically reduce plant-available water reserves. High soil temperatures, often reaching 40-45C at 0-5 cm depth for 4 to 6 hours a day, further aggravate the frequency and intensity of drought stress experienced by shallow-rooted crops.

The principal impact of deforestation on chemical and nutritional properties is related to a decrease in the organic matter content of the soil and to disruption in nutrient-recycling mechanisms owing to the removal of deep-rooted trees. The decrease in soil organic matter content is mostly due to the high rate of mineralization caused by high temperatures. The absence of actively growing roots in the subsoil horizon leads to leaching of bases (e.g. Ca, Mg, K, Na) and increase in soil acidity. In addition to leaching, loss of N and S also occurs owing to volatilization.

Table 9.8 Worst-case scenario regarding the adverse effects of deforestation on soil productivity

Physical effects Chemical and nutritional effects
Compaction, crusting, increased strength Loss of soil organic matter, nitrogen, and sulphur
Accelerated erosion Leaching of bases
Loss of clay and soil colloids Acidification
Drought stress Reduction in soil biological activity
High soil temperatures Disruption of nutrient recycling

Table 9.9 Technological options to minimize the adverse effects of deforestation

Activity Recommended practice
Time of land clearing During dry season when soil moisture is low
Method of land-clearing Manual felling with chainsaw
Mechanized clearing Preferably with shearblade
Management of fell biomass In situ burning, no windrows
Stumping and root removal Remove manually from the top 30 cm, or leave intact
Protective cover Plant an aggressive cover crop, e.g. Mucuna, Desmodium spp. Puereria, etc.
Seedbed preparation No-till or conservation tillage
Erosion management Vegetative hedges, e.g. Vetiver, Leucaena, etc.

The magnitude of these adverse effects depends on the method of deforestation and on the soil and crop management practices. In addition, there exists a strong interaction with soil type, rainfall regime, nature of the existing vegetation, ambient soil moisture content, and microclimate. Technological options for minimizing the adverse effects of deforestation are outlined in table 9.9. It is well known that the adverse effects of deforestation are more severe for mechanical than for manual land-clearing. The adverse effects of mechanical clearing (soil compaction and accelerated erosion) are generally less severe for shearblade than for treepusher or bulldozer blade methods of tree felling. Compaction and structural degradation are more severe when soil wetness is high at the time of landclearing (Ghuman and Lal 1992). Stumping and removal of roots, which is necessary only to facilitate mechanized farm operations, should preferably be done manually. Root ploughing is disruptive and causes considerable soil disturbance. Windrowing also scrapes topsoil and concentrates nutrient-rich ash in narrow strips. Management of the soil structure and erosion control can be achieved by sowing a quick-growing cover crop. The cover crop should preferably be a legume, e.g. Mucuna utilis, Pueraria phaseoloides, Centrosema spp., or Desmodium spp. Erosion control on sloping lands can be achieved by establishing vegetative hedges (e.g. Vetiver, Leucaena, Gliricidia) and other multi-purpose trees and woody shrubs. Adoption of agro-forestry practices also enhances nutrient recycling and minimizes leaching losses of bases.

Enhancing the nutrient capital of the soil is critical to increasing the agricultural productivity of these soils of low inherent fertility. Soil fertility is further depleted by deforestation and biomass removal and/or burning. Therefore, judicious application of fertilizer needs careful consideration. To some extent, nitrogen can be supplied through biological fixation. However, other nutrients, including Ca, Mg, and P, must be made available from off-farm sources. Admittedly, resource-poor farmers cannot afford capital-intensive inputs. None the less, essential nutrients must be supplied, through application of either organic manure or mineral fertilizer, if high yields are expected on a sustained basis.

Deforestation and the emission of radiatively active gases

Deforestation strongly affects the dynamics of soil organic matter. Experiments conducted in Africa (Greenland and Nye 1959; Nye and Greenland 1960; Lal 1976; Juo and Lal 1977; Aina 1979; Lal et al. 1980; Ghuman and Lal 1991,1992) show rapid decline in soil organic matter content following deforestation and cultivation. The magnitude of carbon decline in the top 5 cm depth can be as much as 50 per cent in 12 months and 60 per cent in 18 months. The organic carbon (C) content of the top 30 cm depth declines by about 50 per cent within 10 years of deforestation and intensive cultivation. Examples of the carbon loss from soils of the humid tropics within 10 years of deforestation and intensive cultivation are shown in tables 9.10-9.12. The rate of C loss may be as much as 1.13 mg/ha/yr from soil managed by conservation tillage and agro-forestry to 5.60 mg/ha/yr for soils managed with a plough-based conventional tillage system. That being the case, newly cleared land in the humid tropics may release between 98.7 billion kg C/yr and to 218.8 billion kg C/yr, with a mean emission rate of about 154.3 billion kg C/yr.

Table 9.10 Loss of organic curbon with continuous and intensive cultivation with no-till and agro-forestry in 10 years following deforestation

Depth (cm) Organic C (%) Bulk density (mg/m3) Total soil carbon (mg/ha) Carbon emission in 10 years (mg/ha)
  Initial Final Initial Final Initial Final  
0-10 2.50 1.50 1.10 1.40 27.5 21.0 6.5
10-25 1.40 1.00 1.25 1.45 26.3 21.8 4.5
25-50 0.90 0.80 1.30 1.45 29.3 29.0 0.3
Total         83.1 71.8 11.3

Source: Lal (1991).

Table 9.11 Loss of organic carbon with continuous and intensive cultivation using plough-based mechanized systems in 10 years following deforestation

Depth (cm) Organic C (%) Bulk density (mg/m3) Total soil carbon (mg/ha) Carbon emission in 10 years (mg/ha)
  Initial Final Initial Final Initial Final  
0-10 2.5 0.5 1.10 1.5 27.5 7.5 20.0
10-25 1.40 0.4 1.25 1.45 26.3 8.7 17.6
25-50 0.9 0.3 1.30 1.45 29.3 10.9 18.4
Total         83.1 27.1 56.0

Source: Lal (1 991).

The loss of organic C from soils under shifting cultivation is less than that from soils under intensive cultivation. Nye and Greenland (1960) observed that the loss of organic carbon in 100 years may be 20 per cent for a soil with 12-year fallow cycle to 45 per cent for a soil with 4-year fallow cycle. The annual loss of C due to shifting cultivation may be as much as 0.27 mg/ha. If shifting cultivation is prac tised on about 25 million ha, the total loss of C due to shifting cultivation is estimated at 6.25 billion kg C/yr. In addition to C, biomass burning also causes release of several other greenhouse gases, e.g. CO2, CO, CH4, and NOx.

Table 9.12 Changes in soil organic carbon (SOC) content of the surface 0-5 an layer of two soils in southern Nigeria

Alfisol at Ibadana

Ultisol at Okomub

   

DC

   

DC

Year Organic carbon (%) %/yr Average (%/yr)c Year Organic carbon (%) %/yr Average (%/yr)c
1978 2.17 1984 1.8        
1979 1.61 - 25.8 - 25.8 1985 1.4 - 22.2 - 22.2
1982 1.54 -1.5 -7.3 1986 1.45 +3.6 -9.7
1984 1.14 -13.0 -7.9 1987 1.05 -27.6 -13.9
1985 1.24 +8.8 -6.1 1988 1.15 +9.5 -9.0
1986 1.30 +4.8 -5.0        
1987 1.09 -16.2 -5.5        

a. The data from Ibadan are from Watershed 1.
b. The data from Okomu are from the manually cleared plots; data recalculated from Ghuman and Lal (1991).
c. The average (%/yr) is calculated for each year on the basis of the original SOC content.

Deforestation and hydrological balance

Deforestation of TRF can drastically alter the components of the hydrological cycle:

P = I + R + DS + D + > Edt,

where P is precipitation, I is infiltration, R is surface runoff, DS is soilwater storage, D is deep drainage, E is evapotranspiration, and t is time. Deforestation decreases I and DS and increases R and D components. In general, deforestation may also increase E. The change in E, however, may also depend on the land use.

Several experiments have demonstrated the effects of clear-cutting on the increase in total water yield. The impact of deforestation on the hydrological balance of a 44 ha watershed was studied at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. Prior to partial deforestation in 1978 and complete defor estation in 1979, measurements of surface and subsurface flow were made under the forest cover from 1974 to 1977. Under the forest cover, the interflow was 0.4 per cent to 1.4 per cent and total flow 0.8 per cent to 2.7 per cent of the total rainfall. Partial clearing in 1978 increased interflow to 1.2 per cent and increased total flow to 6.6 per cent of the total rainfall (table 9.13).

Table 9.13 Effects of partial clearing in 1978 on total water discharge from Watershed 1

Parameters  
Rainfall (mm) 785.8
Surface flow (mm) 42.7
Surface flow (% of rain) 5.4
Subsurface flow (mm) 9.4
Subsurface flow (% of rain) 1.2
Total yield (mm) 52.1
Total yield (% of rain) 6.6

Note: The partial clearing was of 3.1 ha out of 44.3 ha.

Table 9.14 Hydrological components on an annual basis for Watershed 1, 1979-1986

Year Annual rainfall (mm) Subsurface flowb (mm) Surface flow (mm)

Total water yield

Apparent evapo transpirationa

        mm % of rainfall mm % of rainfall
1979 1,435.5 28.0 73.4 101.4 7.1 1,334.1 92.9
1980 1,449.7 73.1 90.0 163.1 11.3 1,286.6 88.8
1981 1,074.5 58.9 28.9 87.8 8.2 986.7 91.8
1982 851.5 50.9 25.9 76.8 9.0 774.7 91.0
1983 897.6 45.8 21.3 67.1 7.5 830.5 92.5
1984 1,162.2 58.9 27.1 86.0 7.4 1,076.2 92.6
1985 1,675.7 18.5 93.2 111.7 6.7 1,563.9 93.3
1986 1,164.1 1.9 51.7 53.8 4.6 1,110.3 95.3

a. Evapotranspiration includes soil water storage and groundwater recharge.
b. Subsurface flow is underestimated during wet years because it is computed as a part of surface flow during the storm runoff.

The entire watershed was cleared in 1979 and cultivated to food crops. The data in table 9.14 show that the total water yield ranged from 4.6% to 11.3% of the rainfall received. Because of the bimodal distribution of the rainfall, the hydrologic balance was computed separately for each growing season. The hydrologic balance showed that total water yield ranged from 1.4% to 11.8% for the first season (table 9.15) and from 0.8% to 18.1% for the second season (table 9.16). The intermittent stream, with a trace of flow after heavy rain and no flow during the dry season, became a perennial stream that recorded a measurable flow throughout the dry season (table 9.17).

Table 9.15 Hydrological components for the first growing season (March-July), 1979-1987

Year Annual rainfall (mm) Subsurface flowb (mm) Surface flow (mm)

Total water yield

Apparent evapo transpirationa

        mm % of rainfall mm % of rainfall
1979 846.1 7.0 89.8 96.8 11.4 749.3 88.6
1980 604.3 1.2 7.0 8.2 1.4 596.1 98.6
1981 636.8 20.2 17.3 37.5 5.9 599.3 94.1
1982 615.2 28.4 17.6 46.0 7.5 569.2 92.5
1983 580.9 22.3 15.2 37.5 6.5 543.4 93.5
1984 681.6 23.6 13.9 37.5 5.5 644.1 94.5
1985 935.7 10.8 52.1 62.9 6.7 872.8 93.3
1986 714.2 1.8 36.9 38.7 5.4 677.3 94.8
1987 723.5 36.4 49.2 85.6 11.8 637.9 88.2

a. See notes to table 9.14.
b. See notes to table 9.14.

Table 9.16 Hydrological components for the second growing season (AugustNovember), 1979-1986

Year Annual rainfall (mm) Subsurface flowb (mm) Surface flow (mm)

Total water yield

Apparent evapo transpirationa

        mm % of rainfall mm % of rainfall
1979 585.8 0.03 4.6 4.6 0.8 581.2 99.2
1980 845.4 71.90 81.1 153.0 18.1 692.4 81.9
1981 432.4 33.50 11.6 45.1 10.4 387.3 89.6
1982 223.6 19.20 8.1 27.3 12.2 196.3 87.8
1983 230.6 19.20 6.1 25.3 11.0 205.3 89.0
1984 480.6 30.50 13.2 43.7 9.1 436.9 90.9
1985 735.5 6.90 41.1 48.0 6.5 687.5 93.5
1986 379.2 0.10 13.9 14.0 3.7 365.2 96.3

a. See notes to table 9.14.
b. See notes to table 9.14.

Table 9.17 Hydrological components for the dry season (December-February) for Watershed 1, 1979-1987

Year Seasonal rainfall (mm) Subsurface flow (mm) Surface flow (mm) Total water yield (mm)
1979 3.6 0.0 0.0 0.0
1980 23.6 0.0 0.0 0.0
1981 5.3 2.0 0.08 2.1
1982 12.7 5.0 0.10 5.1
1983 0.0 3.6 0.03 3.6
1984 86.1 4.1 1.1 5.2
1985 0.0 3.6 0.0 3.6
1986 7.6 0.0 0.0 0.0
1987 18.8 3.9 0.0 3.9

Note: The data for December are taken from the previous year.

An increase in the magnitude of interflow and its continuous discharge throughout the dry season may be attributed to the replacement of deep-rooted perennials with high water requirements with shallow-rooted annuals with relatively fewer water requirements. Further, annuals were not grown during the dry season.

Sustainable use of the TRF ecosystem

Criteria for sustainable land use

The tropical rain-forest ecosystem must be used, improved, and restored. Continuous depletion of these resources has economic and ecologic ramifications at local, regional, and global scales. Sustainable use of soil and water resources in the TRF ecosystem should take the following into consideration:

the nutrient capital of the soil resources should be enhanced by applications of chemical and organic fertilizers;

the management systems adopted must optimize energy flux as well as energy use efficiency - energy efficiency alone is not adequate in view of increasing population pressure;

Iosses of nutrients and water out of the ecosystem should be minimized;

nutrient recycling mechanisms from subsoil to surface horizons must be an integral aspect of the land-use system;

land degraded by past mismanagement must be restored by afforestation with ecologically adapted and quick-growing species.

Land capability assessment

Land capability assessment is necessary for the rational utilization of forest resources. Sustainable use of TRF resources necessitates a detailed and accurate inventory of the soil, water, vegetation, and climatic characteristics of the region. These inventories/surveys should be conducted at reconnaissance scales (1: 50,000 to 1 :1,000,000) and detailed scales (1 :10,000 to 1:50,000). The land resources should then be classified according to their potential capability as follows (FAO 1982):

Forest land

There are several types of forest land:

(a) Natural forested land should be preserved as natural forest and left alone. It has limitations of topography, shallow/stony soils, poor water regime, etc. Some examples are marginal steep lands, forests in the vicinity of regions with short supplies of firewood, inaccessible areas, small islands, and regions with other sociopolitical connotations.

(b) Production forests are suitable for managed logging of timber and other forest products.

(c) Planted or man-made forests are fertile, prime lands and are suitable for tree plantations, e.g. Gmelina, teak, Cassia.

(d) Protected forests are forest reserves protected in order to preserve the natural biodiversity.

Arable land

Arable land is prime agricultural land and is suitable for supporting continuous and intensive agriculture for food-crop and livestock production. Such land should be developed and managed according to ecologically compatible methods of deforestation and land development. When deforestation for arable land use is inevitable, land development should be carefully planned and implemented according to scientific guidelines.

Guidelines for land use in the TRF ecosystem

The development of TRF for alternative land uses has become a global issue. For some countries, the question is no longer whether to remove tropical forest for alternative land uses; the important consideration is how much to remove and by what method so that ecological concerns are adequately addressed. It is the ill-planned and improper management of TRF that has created severe ecological, economic, and socio-political problems. The sequence of steps needed to achieve a rational use of the TRF ecosystem is outlined below:

1. Iand capability assessment;
2. choice of proper land use (e.g. arable land, protected forest, manmade forest);
3. use of proper methods and time of deforestation (e.g. manual, chainsaw, shearblade);
4. adoption of soil conservation measures (e.g. cover crop, mulch farming, vegetative hedges);
5. use of science-based agronomic techniques of soil and crop management (e.g. balanced fertilizer use, proper crop rotation and cropping sequences, appropriate tillage methods, and integrated pest management).

Best management practices for sustainable agriculture

Some soils supporting the TRF ecosystem can be converted to intensive arable land use with sustained production provided that:

(a) expectations of agronomic yields are not too high,

(b) the soil and crop management systems adopted ensure the replenishment of plant nutrients harvested in crops and the maintenance of biophysical resources,

(c) the soils are taken out of production and put to restorative land use long before the degradative processes are set in motion.

Some research-proven agronomic practices based on these guidelines are listed in table 9.18. Just as use of prime agricultural land is essential not only for food-crop production but also for establishing pasture and forest plantations, so is the use of chemical and organic fertilizers for enhancing soil fertility. Most soils of the TRF ecosystem are of low inherent fertility. Enhancing soil fertility, therefore, is crucial to sustained agricultural productivity.

Imperata control

Land misuse and severe soil degradation encourage encroachment by Imperata cylindrica and other noxious weeds. It is important to maintain soil fertility at a high level to curtail encroachment by lmperata and to reclaim already infested lands. Reclamation of Imperata-infested land requires a combination of mechanical, chemical, and biological measures. Soil inversion, to uproot rhizomes and expose them to high temperatures during the dry season, followed by the use of systemic herbicides and sowing an aggressively growing cover crop, is essential to eradicate the noxious weed. Biological methods of Imperata control, slow as they may be, are often effective on a long-term basis. Preventing encroachment by adoption of the best management practices (BMPs) outlined in table 9.18 should be the best overall strategy.

Table 9.18 Best management practices for sustainable land use in TRF ecosystems

Arable land use Pasture development Agro-forestry Forest plantations
Use prime land, and avoid marginal, steep, or shallow soils Use prime land, and avoid steep and shallow soils Use prime land of high inherent fertility Use prime land with no serious limitations
Remove forest by manual methods, or by shearblade Use proper clearing methods, e.g. manual, slash and burn, etc. Tree defoliants can also be used in regions with low tree density. Dead trees can be left standing Clear land by manual methods or shearblade techniques Clear existing vegetation by manual methods of slash and burn or by shearblade. Some roots and stumps can be left intact
Use cover crop and mulch farming techniques for soil and water conservation Seed with suitable and ecologically adapted mixture of grass and legumes Choose native tree spe- cies that do not aggressively compete with annuals Seed a leguminous cover crop immediately
Make frequent use of planted fallows Maintain soil fertility as per soil test values. Balanced fertilization is important Proper tree management is crucial. Establish tree seedlings through the leguminous cover by suppressing it through chemical or mechanical means. Cover crop management is crucial to tree establishment
Wherever feasible, integrate woody perennials and livestock with food-crop annuals   Choose appropriate crops and cropping sequences Use balanced fertilizer based on soil test values and tree requirements
Use chemical and organic fertilizers judiciously   Manage soil fertility in relation to cropping intensity and soil test values Use effective soil and water conser vation techniques
Choose appropriate crops and cropping sequences      

Restoring degraded forest lands

Restoration of degraded lands in TRF ecosystems is a high priority if the rate of new deforestation is to be reduced. The choice of land restorative measures to be adopted depends on the type of degradation, the processes involved, and antecedent soil properties and vegetation. Knowing the critical/threshold levels of soil properties, beyond which the soil's life support processes are severely jeopardized, is crucial in this endeavour. Land restorative techniques for soils degraded by different processes are outlined in table 9.19.

Research needs

In view of the ever-increasing demand on limited and fragile resources, the question most often asked is whether soil productivity in TRF ecosystems can be sustained with intensive and continuous farming. The available research data indicate that most tropical soils can be intensively cultivated and produce high and sustained yields by adopting BMPs based on an ecological approach to agriculture. In this connection, land-clearing techniques play an important role. The effects of improper land-clearing methods are observed even 8-10 years after the land has been cleared, and especially when the overall soil fertility has drastically declined. Adopting a land-use system that may produce, say, 60-80 per cent of maximum returns and that avoids causing environmental degradation is a better choice than land-use systems that bring high short-term returns but severely degrade the resource base.

An optimum resource utilization should be based on scientific data obtained through well-designed and adequately equipped long-term experiments. To start meeting this objective, additional research information is needed on evaluating the following:

land capability and the development of criteria for the choice of rational land use and for appropriate methods of removing vegetation,

the economic and environmental consequences of different land-use systems,

methods of restoring forest vegetation and soil quality degraded by land misuse,

ecologically compatible methods of Imperata control,

adaptability of those methods of soil and crop management that enhance production from existing land, thereby reducing the need to clear new land.

Considering the limited resources available and the urgent need to use forest resources efficiently, it is important that priorities are defined and research goals are sharply focused. A coordinated effort is needed to achieve these objectives.

Table 9.19 Land restorative techniques

Soil degradative process Strategies Land restorative techniques
Soil compaction Enhance soil structure Grow planted fallows and deep rooted perennials
  Improve aggregation Use mulch farming techniques
  Enhance activity of soil fauna, e.g. earthworms Avoid excessive vehicular traffic
    Use subsoiling discriminatingly and judiciously
Soil erosion Divert run-on Isolate the area
  Prevent runoff Construct diversion channels
  Minimize raindrop impact Establish permanent ground cover
  Enhance soil structure Use fertilizets and manures
    Establish vegetative hedges on the contour
    Establish micro-catchments and water-spreading devices to enhance water infiltration
Nutrient depletion Stop fertility mining practices Take land out of production and establish planted fallows
  Use balanced fertilizer Augment nutrient capital by the addition of chemical and organic fertilizers
  Develop nutrient recycling mechanisms Establish native trees and deep rooted shrubs to facilitate nutrient recycling

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---- 1992 93. Towards Sustainable Development. Washington D.C.: WRI.

(introduction...)

Introduction
The value of the coastal zone and oceans
The main problems and their causes
Remedies
References

 

A. Chidi Ibe

Introduction

The coastal zone and oceans surrounding Sub-Saharan Africa, with their vast resources of food, energy, and minerals, not only are composed of various fragile ecosystems, but are scenes of a variety of often conflicting uses. At present, the uncontrolled development of the coastal zone and ocean and the almost haphazard exploitation of their natural resources threaten to turn the promise of economic prosperity into an environmental nightmare that portends great dangers for present and future generations. There is the urgent need to put in place national management policies that address the environmental controls and procedures to be applied in pursuit of economic development. However, the oceans have no physical boundaries corresponding to national jurisdiction and problems originating from one country easily become those of another. Consequently, although it is recognized that remedies should be effected at the national level, such remedies should be undertaken in the framework of and as part of wider regional and global agreements and policies aimed at the sustainable development of the entire coastal and ocean environment.

The value of the coastal zone and oceans

The coastal zone and oceans of Sub-Saharan Africa constitute a huge storehouse of food, energy, and mineral resources that, if exploited rationally, could be the basis for sustainable development. The coastal zone is in addition a site of human habitation and of concomitant infrastructures for agriculture, industrial development, recreation, and communication (including harbours and ports).

The northern and southern sectors of the western African coastline are the scene of periodic profound upwelling, and upwelling, although weaker, has also been reported in the equatorial sections (Longhurst 1962; Ibe and Ajayi 1985). On the eastern African coast, the picture is much the same, and the Ras Hafun upwelling off the northern coast of Somalia has been extensively described (Newell 1957, 1959; Winters 1976). These areas of upwelling are particularly rich in fish production. Various species of crustacea, including lobsters, deep water shrimps, and prawns, are common. In the coastal lagoons, fish, prawns, and molluscs are also abundant and help to sustain the needs of local populations.

In addition to species of economic importance, there are vulnerable and endangered species such as sea turtles, dugongs, and manatees whose preservation contributes to marine biological diversity (Howell 1988a). Waterbirds are also important; over 100 species from over 25 families are associated with the eastern African coast but are threatened (Howell 1988b).

Some of the coastal countries in Sub-Saharan African are, to varying degrees, oil producers and a few, such as Nigeria and Gabon, are important exporters; others have important refineries and the potential for the development of further production and refining appears substantial. Besides oil and gas, commercial energy production is dominated by hydropower and coal. A survey of the potential of ocean energy in the West and Central African region noted that attractive resources exist for ocean thermal energy conversion, oceanic bioconversion, tides and salinity exchange, but the prospects for wave and current energy are rather poor, except along the southern African coastline, where it has been determined that a favourable 10 kW/m of waterfront is available up to 1 km offshore and about 50 kW/m of waterfront up to 30 km offshore (UNEP 1983).

Non-energy mineral resources are exploited in the coastal zone of Sub-Saharan Africa. These are mostly placer minerals (e.g. in Sierra Leone and Tanzania) and vast deposits of construction materials, including sand, gravel, and limestone. Phosphate mining and salt extraction are ongoing activities in some sectors of the African coastline, as is open-pit mining. Lead-silver ores were previously quarried in Kinangoni, Kenya. In addition, the coastal zone of Africa is known to have the potential to produce the vast array of minerals that would be expected from Africa's present-day geology and evolutionary history (Ibe 1982; Ibe et al. 1983).

The coastal zone and oceans, with their ecosystems of coral reefs, seagrass beds, mangroves, etc., are repositories of biological diversity in addition to serving as food "regenerating" factories.

Owing to the pattern of early contacts with the outside world, which were mainly coast based, most African cities of note are coastal cities. For example, in western Africa, the capitals of all but three of the countries from Mauritania to Namibia are situated on the coast and it is on the coast that the major industrial developments are taking place. In Ghana, 35 per cent of the population live in towns and 60 per cent of industry is concentrated in the coastal Accra/Tema metropolis. In Nigeria, about 10% of the total population of over 80 million live in Lagos, which is also the centre for 85% of the country's formal industry. The picture of coastal development in eastern Africa follows a similar pattern (Portmann et al. 1989). To promote international and national communication (transport) and trade, harbours and ports have often been constructed that are "out of tune" with the natural environment. Tourism is a booming industry in eastern Africa and a promising one in western Africa. Agriculture, including fishing and aquaculture, is practiced on a largely artisanal, sometimes industrial, scale.

The coastal zone and oceans serve a number of indirect functions that nevertheless add to their usefulness as an integral component of a country's socio-economic fabric. Such functions include the removal of wastes, protection from storms, absorption of atmospheric carbon dioxide (CO2), mediation of climate, purification of air, and recreation.

The main problems and their causes

It is perhaps ironic that the problems of the coastal zone and ocean in Sub-Saharan Africa derive from their usefulness and in particular from the settlement of humans on or near the coast.

The open ocean, however, seems as yet to be largely unaffected by either the environmental degradation wrought by humans or the overexploitation of its natural resources. For living resources in the open ocean, the only danger signal comes not from the activities of coastal states but from foreign fleets (from Japan, South Korea, Taiwan, and the former USSR, among others), which "poach" fish from these waters. For example, tuna in the western Indian Ocean (eastern Africa) is heavily exploited by these foreign fleets and recent indications are that yellow and southern blue fin tuna and bill fish are overexploited and that bigeye tuna and albacore are fully exploited (Ardill 1984). Bryceson et al. (1990) stated that this fishing pressure with highly sophisticated gear has an adverse impact on smaller-scale operations conducted by the fishing fleets of the region, and that artisanal fishermen have noticed marked decreases in catches of large pelagic migratory species.

On the Atlantic coast of Africa, similar pressures exerted by foreign fishing fleets have produced similar consequences (e.g. depletion of deep water prawn/shrimp resources) for the local fishing industry (Ajayi, personal communication).

Besides the operations of foreign fishing fleets, which are sometimes illegal, many of the fisheries of the region are artisanal and based mainly in the coastal zone. Here population pressures have increased consumption and demands and led to the use of destructive fishing methods.

In the coastal zone of eastern Africa, the most environmentally destructive method of fishing is dynamite blasting, mostly associated with coral reef habitats. Bryceson (1978a) reported that repeated blasting over a long period of time has meant the destruction of extensive areas of coral reef and the decline of their fisheries' productivity. The livelihood of artisanal fishermen who employ more traditional methods is threatened. Bryceson (1978a) also reported that spear-fishing had been banned in most countries of the region owing to its damaging effects on reefs and on populations of particularly vulnerable species. For the same region, Kayambo (1988) points out that depletion of the mollusc population as a result of its intensive collection for export and sale to tourists has been a cause for concern.

In the coastal zone of western Africa, in response to increasing demands for fish and fish products, trawling now prevails in areas formerly dominated by traditional fishermen. However, these operations are largely unregulated (or do not conform to regulations where they exist), with incorrect mesh sizes resulting in destructive fishing, including the catching of undersized fish (Ajayi, personal communication).

It is, perhaps, pertinent to mention that on the eastern and western coasts of Sub-Saharan Africa, the potential for aquaculture development is great and people are being urged to take it up as a way of increasing overall fish production. However, experience from its limited practice shows that the potential for environmental degradation (e.g. associated with clearing mangroves) is also great.

Mining of sand (siliceous and calcareous), gravel, and other construction materials (e.g. Iimestone) from estuaries, beaches, or the nearshore continental shelf is common (Ibe 1982, 1987a,b; lbe and Quelennec 1989) in the coastal states and islands of Sub-Saharan Africa. The mining of sand and gravel from coastal rivers and particularly from estuaries tends to diminish the amount of fluvial sediment input to the coastline, thereby accelerating shoreline retreat. Sand extraction directly from beaches seriously depletes the sediment pool available, and beach retreat is either induced or accelerated. Dredging of sand from the inner continental shelf is an obvious cause of beach erosion in Africa. This is because the beaches along these coasts exist in dynamic equilibrium with the nearshore continental shelf. Therefore, dredging of sand/gravel for replenishment, land reclamation, or other civil engineering construction from the shore area or, for that matter, anywhere else within the dynamic system inevitably disrupts this equilibrium and enhances shoreline retreat. Countries where this problem has been documented include Liberia, Sierra Leone, Cote d'Ivoire, Nigeria, Mauritius, Tanzania, Kenya, the Seychelles, and Mozambique (Ibe et al. 1983; Ibe 1986c; Ibe and Quelennec 1989; Bryceson et al. 1990).

Besides the increased threat of erosion, the mining of construction materials from the coastal zone has a tendency to disrupt fragile ecosystems such as coral reefs and mangroves and affect their productivity (Ibe 1982; Ibe et al. 1985).

Lead-silver ores were quarried in Kinangoni, Kenya, and were a cause for concern as regards metal pollution, so that the quarries had to be closed (Muslim 1984).

The exploration, exploitation, refining, and transportation of oil and gas in Sub-Saharan Africa, although contributing to economic development, bring worrying problems because these activities routinely contribute a variety of pollutants to the coastal zone and oceans. These include hydrocarbons from occasional spills but, perhaps more importantly, from chronic low-level releases associated with leaking valves, corroded pipelines, ballast water discharges, and production water effluents. Drilling fluids contain diesel and some toxic chemicals that cause pollution. Heavy metals, particularly vanadium and nickel, are introduced through oil-field operations and are known to affect life forms.

Another impact of oil production is the initiation or exacerbation of subsidence in the fragile coastal zone. The main effect of fluid extraction is the reduction of fluid pressure in the reservoir, thus leading directly to an increase in the "effective stress" (or grain to grain stress) in the system. Compaction results and the sedimentary basin subsides (Cooke and Doornkamp 1974). The subsequent progressive inundation of the coastline results in accentuated erosion. Ibe et al. have documented this phenomenon in Nigeria's oilproducing Niger delta (Ibe et al. 1985; Ibe 1988b).

In oil-producing coastal states, a network of canals for hydrocarbon exploitation and transportation, on or near the coast, constitutes a visible structural modification of the coastal zone that has adverse effects on coastline migration.

As stated elsewhere, perhaps the greatest problem in the coastal zone arises from development activities linked with coastal settlements. Coastal towns are by far the most developed in Sub-Saharan Africa and, by implication, the location of residential, industrial, commercial (including harbour and port construction), agricultural, educational, and military facilities in the coastal zone is high (Ibe 1988a, 1989). The increasing awareness of the revenue-generating potential of tourism has also led to increased construction of tourist facilities on beaches along the coast. Construction activities in the coastal zone loosen the sediment binding by removing the surface revetments and increasing rainwater runoff. Thus soil erosion is enhanced. On the other hand, structures constructed on the coast, by strengthening the soil, may lead to decreased sediment supply to the shoreline. The opposite problems of increased siltation and sediment starvation along the coast result, depending on the local physiographic conditions.

The pollution caused by these settlements and the accompanying development activities threatens to make nonsense of the concept of sustainable development. The pollution results primarily from raw or insufficiently treated domestic sewage and from untreated toxic and deleterious wastes from industries, which generally discharge directly into rivers, estuaries, and the nearshore ocean. Preliminary results from pollution-monitoring projects instituted by United Nations agencies, including the Intergovernmental Oceanographic Commission of UNESCO in Eastern and Western Africa, show that pollution by pathogenic organisms, pesticides, chemical fertilizers, and petroleum hydrocarbons is widespread, while metal pollution occurs as hot spots close to industrial sites.

Solid matter (litter) from industries, households, shipping, and the tourist trade poses a problem of an unsightly and irritating nature, but it also has serious public health implications.

The construction of ports, harbours, and piers for national and international trade has a direct negative impact on the environment. This is because, for the most part, these structures lie perpendicular, or nearly so, to the littoral zone, thereby causing acute down-drift erosion. This problem has been documented in Benin, Togo, Nigeria, Liberia, Ghana, Cote d'Ivoire, South Africa, Tanzania, and Somalia, among others. In most of these cases, attempts at solving the harbour-induced erosion have further exacerbated the problem (Ibe 1986a,b).

Increased clearing of coastal vegetation at construction and mining locations or for the establishment of agricultural farms or the expansion of settlements leads to increased surface runoff and makes the exposed area extremely vulnerable to mass movement and to erosion by winds, currents, and water. Large areas of mangroves have been cleared in Kenya, Tanzania, Ghana, and Mozambique for the production of salt by evaporation (Ibe 1987a; Semesi 1988). In Mauritania, Guinea, Sierra Leone, Liberia, Togo, and Angola, open peat mining in littoral zones also contributes to the destruction of vegetation and the acceleration of coastal erosion. The clearance of mangroves is particularly serious because mangroves, in addition to serving as windbreaks, provide excellent spawning and nursery grounds for a variety of coastal organisms, including fish, crustaceans, and molluscs. The loss of mangroves therefore has serious implications for the productivity of coastal ecosystems.

An additional possible problem in coastal areas relates to the expected effects of global warming on shallow ocean and coastal zones, in particular the impact of the associated rise in sealevel. The negative implications of global warming, if they occur, will be considerable for natural and man-made ecosystems, human and animal health, and the spatial and temporal characteristics of natural and human resources (Ibe 1989; Ibe and Ojo 1993; Ojo 1992; Tobor and Ibe 1992).

Remedies

Owing to the abundant natural resources with which they are endowed, the coastal zone and oceans of Sub-Saharan Africa hold the key to the social and economic well-being of the coastal states. This is on condition that these resources are exploited in a rational and prudent manner that ensures economic gains while preserving the integrity of the environment. This is the central thrust of the concept of sustainable development.

Today, the exploitation of the natural resources of the coastal zone and near-shore ocean is almost haphazard and has very little respect for the quality of the environment. A degraded environment cannot sustain the renewable resources needed to support the teeming populations that have thronged to coastal areas on account of the presence, in the first place, of these resources; the quality of life of the people deteriorates, and the ensuing struggle for human survival puts additional pressures on the environment and the increasingly limited natural resources. A sort of vicious cycle comes into play. The need is therefore urgent to break this cycle. As has been emphasized elsewhere, the problems of Sub-Saharan Africa as far as the open ocean is concerned are few but they are multifarious for the coastal zone. It would appear reasonable, therefore, to focus suggested remedies on this critical zone.

Attempts at piecemeal solutions of coastal zone problems seem to have failed woefully on account of their intricately interwoven nature. The resulting conflicts are sometimes difficult to solve unless institutionalized frameworks exist. National coastal zone management policy, with adequate legal provisions and providing linkages between the exploitation of natural resources, the conservation of these resources, the preservation of environmental quality, and the promotion of human well-being, seems to be a pressing need. Such a policy, which should have as a core objective the relief of population pressures on the coastal environment, must state clearly not only the concern of a given country for rational coastal zone development but also the procedures to be applied in the coastal zone. In this regard, inspiration and lessons should be drawn from the prevalent practice in most countries in the industrialized world where, despite a variety of existing controls to reduce pressures on the coastal zone, specific laws have been passed to give greater precision to the legal status of coastal zone management and control. The Coastal Zone Management Act of 1972 in the United States of America and Decree no. 79-716 of 17 August 1979 in France are particularly instructive (Ibe 1987c, 1988a).

There will be a need to create (where they are lacking) or to strengthen (where they exist) appropriate national infrastructures to ensure effective compliance with such policies. However, although action at the national level is desirable, it must be borne in mind that, spatially, the oceans and the coastal waters (lagoons, estuaries, bays, creeks) that are in communication with them have no physical boundaries conforming to national jurisdiction. The transportation of pollutants originating from land-based sources in one country to neighbouring countries cannot be prevented physically; the downdrift erosion generated by structures perpendicular to the shore in one country will easily affect another country. The same goes for atmospheric inputs. Oil or toxic chemical accidents at sea transcend national boundaries in their impacts. The meaningful approach therefore should favour integrated and coordinated global resource development and global environmental protection strategies.

Even before but particularly since the 1972 Stockholm Conference on the Human Environment through the United Nations Law of the Sea Conference in 1982 to the 1992 United Nations Conference on Environment and Development in Rio de Janeiro, existing international agreements have implied this global view and contain, for the most part, explicit provisions for capacity building and the transfer of technologies and experience as well as financial assistance, and these issues are of legitimate concern to developing countries. It would appear prudent for coastal states in Sub-Saharan Africa to be parties to existing conventions aimed at the protection of the global ocean and coastal zone and to seek to negotiate from "within" in order to change any provisions that are not in their best interests. In the same vein, these states are encouraged to join the negotiations for future conventions to ensure that their specific concerns are catered for within the global view. Increased global solidarity is imperative in the quest for a healthier ocean and coastal zone and the rational exploitation of their resources towards sustainable development.

As a manifestation of this solidarity, the rich industrialized countries, despite their own troubles (real or perceived), should be willing (even enthusiastic) to assist developing countries, and in particular countries in Sub-Saharan Africa, in their attempts to alleviate poverty. As a developing country leader put it very lucidly many years ago, "poverty is the greatest pollution" in developing countries. Poverty is indeed the key element in the vicious cycle responsible for persistent environmental degradation in developing countries, and it would seem logical that any credible policy aimed at restoring and preserving the environment in Sub-Saharan Africa should have as a principal target the elimination of poverty. This could be done through a combination of the many schemes already proposed - for example, debt forgiveness, debt for nature swaps, interest-free loans for the installation of improved pollution-free technologies in SubSaharan Africa. In making the commitments called for, the rich industrialized countries must recognize that there are few or no other options open to them, because, if the developing countries "sink in a polluted ocean," the bonds and interrelationships that have made the world a global village mean that the developed world would be dragged down as well.

The time for concerted action is now. Fortunately, the Agenda 21 (Chapter 17) programme approved at the 1992 United Nations Conference on Environment and Development (UNCED 1992) affords an effective framework of global action towards the sustainable and equitable development of the entire ocean and coastal areas. It is hoped that the implementation of the provisions of Agenda 21 (Chapter 17) will bring significant improvement and protection to the ocean and coastal environment of Sub-Saharan Africa and will ensure, as was hoped for in the l 985 Brundtland Commission Report, that, in exploiting the resources of this environment, "the needs of the present generation should be satisfied without compromising those of future generations" (WCED 1987).

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