Biodiversity: our common heritage

As a result of pressure from human activity and economic necessity many plant and animal species are disappearing, thereby depleting the world's genetic resource. Our heritage of biodiversity is under serious threat. One of the major themes of international discussion about the environment is to decide what measures should be taken to reduce this threat. How can economic necessities be reconciled with respect for the environment? Never has there been so much discussion about biodiversity as there has been in the last ten years or so, but what exactly do we mean by biodiversity? This term, a contraction of 'biological diversity', covers a number of concepts. Andr\E9 Charrier, professor at the Ecole Nationale Sup\E9rieure d'Agronomie (National Institute of Advanced Agronomy) at Montpellier, France, defines it as follows: 'Biodiversity includes all living organisms, both individuals and their relationship with one another. It is not just a collection of individuals but an interaction system where the characteristics of the individual are no less important than their function. The term genetic resource, refers to the biological material, (genes, individuals, species) taken from biodiversity and used by man for agricultural, industrial and medicinal purposes. Biodiversity is now seriously threatened worldwide and scientists are expressing deep concern. According to the American naturalist A W Wilson, 17,500 tropical plant and animal species disappear each year. Studies indicate that between 25,000 and 75,000 species will be lost by the year 2000. While it is true that extinctions have always taken place, today they seem to be occurring over a much shorter period. Long periods are necessary for the restoration of biodiversity. FAO estimates that some 75% of the genetic diversity of cultivated plants has been lost since the beginning of the century. But the loss of the genetic resource base is not the same in all countries: while in Europe and North America only a few improved varieties of a limited number of species survive and are cultivated, in developing countries the diversity of cultivated species tends to be much greater. For example, in an African village some 10 or 20 varieties of a crop may be grown and a small area only will be devoted to growing modern varieties. In the countries of the South, the loss of genetic resources is much less than might be imagined. The heart of the problem Demographic growth lies at the heart of the problem since the higher the population the more intensive the exploitation of all resources. Forests are cut down, land is cleared, bush fires rage, land is overgrazed. There is misuse of fertilizers and pesticides. Irrigation is mismanaged and there is pollution. Plant and animal habitats are destroyed. Industrial activity and urban proliferation compound the problem. This century has seen the loss of much genetic material and it is economic activity that is the cause, suggests Andr\E9 Charrier. Man has taken a limited number of plant and animal species, those considered to be the best adapted to his immediate needs, and concentrated his efforts on them. But the exclusive use of such varieties, even if they usually perform well, presents a risk of total loss should any fall victim to disease or adverse weather. On the other hand, the traditional practice of growing many different varieties of the same plant was a useful form of insurance, a risk reduction exercise which allowed farmers to minimize damage from disease. Because wild varieties have survived without the help, or interference, of man, these varieties have evolved their own strategies for resisting pests and these strategies could be valuable to us in the future. Diversity as a response to risk is not the only benefit that our biodiversity heritage offers us. Even if the full diversity of varieties is not used at present (and three plants alone, rice, wheat and maize, contribute 41% of our plant food), their existence is no less necessary. Biodiversity is our biological bank of capital resources, says Christian L\E9veque, a scientist working at ORSTOM. It is the great diversity of often increasingly at risk species that are the source of many food, pharmaceutical or industrial products on which we have come to depend: 25% of medicines are of direct plant origin and this percentage rises to 50% if one takes into account products which have been only slightly modified to improve on the natural plant. And yet it is estimated that only 1% or 2% of potentially useful medicinal plants have so far been discovered. While biodiversity is important for health generally, in Africa it is essential since those providing traditional health care have only plants and other natural products to use as medicines. Furthermore, a great many people in the world today do not have access to any other form of medicine. Plant conservation, diversification and transfer It has taken the extinction of many species for people to appreciate fully the value of the biodiversity we have inherited. Genetic resources are now the subject of much debate and these resources include wild populations, indigenous landraces and varieties which have been modified to include improved genetic characteristics. One of the principal recommendations of international organizations is that efforts should be made to conserve the wild relatives of cultivated species. They are found in the species' areas of origin which still harbor many wild species, indigenous varieties and weeds related to modern cultivated plants. The wild species form a natural reservoir for breeders seeking genes for resistance, hardiness or adaptability. In developing countries it is farmers and other rural people who have the responsibility for the evolution of genetic resources: they grow the plants in their farms and gardens. In the developed countries, however, genetic resources are stored in genebanks rather than on the land. Many genebanks were established in the sixties when breeders recognized that the biodiversity on which they depended was beginning to disappear. There are now some 50 large genebanks to which the principle of free access applies and, in theory, any breeder may receive in response to a simple request, a sample of any variety. But even though the importance of conserving genetic material is generally recognized, there appear to be difficulties over the distribution of seed. The International Agricultural Research Centres hold the largest collections of genetic material in the world. The relationship between genebanks and users is still a difficult problem. Genebanks have tended to accumulate enormous collections but they do not always have the means to classify the material properly nor do they always have the facility for multiplying the seed. According to Michael Chauvet and Louis Oliver in their book La biodiversit\E9 Enjeu plan\E9taire - Pr\E9server notre patrimoine g\E9n\E9tique, this is why genebanks are under-used. Keeping or sharing? If the case for maintaining diversity no longer needs to be proved, the means of conservation are still the subject of much discussion. The difficulty is to reconcile the needs of the local population with the needs of the natural world. Putting the forest under a protective umbrella, classifying everything within it and forbidding access are solutions which, for the countries of the south, could only ever exist on paper. Creating arboreta and botanical gardens is another possibility but of more than 670 areas which were created as natural parks in the tropics in the eighties very few still exist today. During a major drought in the Sahel, for example, who can realistically prevent farmers from exploiting land classified as a reserve? International organizations are increasingly trying to reconcile nature conservation with the activities of the people living within a protected area. Local people are being involved in the creation and maintenance of natural parks in a variety of ways which allow sharing of the financial profits which they generate, says Jacques Weber, a researcher at CIRAD. The intention is not to block the natural evolution of the traditional farming system, which in any case would be impossible, but to create an awareness of the value of biodiversity. Nowadays farmers are recognized as having a useful contribution to make to the conservation of genetic resources. Provided there is a guarantee of economic development, local people are usually willing to participate actively in conservation projects. For Gerard Sournia of IUCN, a project has no chance of success if the local population is not involved. People have to feel they are participating actively in the work on the ground. Therefore a variety of jobs which will help involve local people in the protection of resources must be included when planning any reserve.

As a result of pressure from human activity and economic necessity many plant and animal species are disappearing, thereby depleting the world's genetic resource. Our heritage of biodiversity is under serious threat. One of the major themes of...