|United Nations University - Work in Progress Newsletter - Volume 14, Number 2, 1993 (UNU, 1993, 12 pages)|
By Bede N. Okigbo
Of the many invaders that landed on Africa's shores over the centuries, probably few have had greater long-term impact than crops brought in from other continents - notably rice from Asia and maize from the Americas. In a macabre twist, maize supported a huge increase in the African population, thereby providing more slaves for New World plantations. The reverberations of this are, of course, still being felt. In addition, the continent's current surge in population, with its potentially disastrous ecological results, is traceable in some respects to these changed cropping patterns.
In the following article, Bede Okigbo, the Nigerian agronomist who directs the UNU Programme on Natural Resources in Africa (UNU/INRA), discusses the scope of Africa's biodiversity losses and some of the steps being taken by University research to remedy the problem. Dr. Okigbo was educated at the School of Agriculture in Ibadan and at Washington State and Cornell Universities, receiving his doctorate in agronomy from the latter in 1959. He returned to Africa, to the University of Nigeria's Nsukka campus and in 1973 joined the International Institute of Tropical Agriculture (IITA) in Ibadan where he was subsequently named Deputy Director, the post he held when appointed Director of UNU/INRA. - Editor
One of the most serious problems facing humankind today is the increasingly rapid loss of biological diversity in all living things - plants, animals and micro-organisms. The concern is most grave in the world's tropical rain forest regions, where more than half of the world's species are found.
Biodiversity is essential to sustainable agriculture without which the people of Africa could not survive. Already beset with a food crisis which threatens nutritional well-being and political stability throughout the continent, Africa today is suffering a serious loss of biodiversity in its stock of indigenous or traditional crops. The UNU Programme on Natural Resources in Africa (UNU/INRA) has launched a timely project to protect these precious genetic resources.
Some of the first genetic erosion in Africa's indigenous food crops and useful plants resulted from the introduction of Asian rice via the island of Madagascar about 1,000 years ago. Later on, crops such as maize, cassava, groundnuts and cacao were introduced from the newly-colonized lands in the Americas.
These imported crops broadened the spectrum of staple food crops needed to support the rapidly growing African population. Their obvious advantages over local staples increasingly displaced the traditional crops, for various reasons. The newly-introduced crops were free of the diseases to which they had been subject in their original homes. This meant higher yields than the indigenous crops. New crops like cassava flourished better than the native yams. And the imported varieties could be prepared in culturally acceptable ways.
A more recent cause of losses in biodiversity in African stocks is the broad complex of changes that come under the rubric of "modernization." This encompasses an all-pervading spectrum of changes in agriculture, industry, development strategies, technologies, and urbanization. These processes, in turn, are associated with changes in attitudes, values, lifestyles, behaviour, social mobility, business organizations, management, and political systems.
Modernization has generally meant the replacement of traditional subsistence slash-and-burn farming with more commercially-oriented, often mechanized agricultural systems that are usually environmentally degrading. Further pressure comes from mechanized logging operations which, in the search for a narrow spectrum of timber species, destroy much "unwanted" landscape.
Another major modem cause of genetic erosion is related to the so-called "Green Revolution," and the promotion of a few uniform high-yield varieties (HYV) of maize, rice or groundnuts as cash crops. These are grown as monoculture row crops over large areas, with costly inputs of fertilizers and pesticides. Although they are more environmentally stressful and less disease resistant, the HYV are given research priority by extension services which also promote and distribute them more vigorously than traditional crops. There is also the problem of change in food preferences in favour of the high-yield varieties, which are tailor-made for a wider range of convenience food preparations.
The genetic erosion problem is exacerbated by the fact that over 50 per cent of edible and useful African crop plans are still wild. Environmental damage not only causes the genetic erosion of wild plants; it also puts a stop to efforts to domesticate and experiment with them. Added to the problem is the loss of indigenous knowledge about traditional stocks as older farmers die and younger ones lack knowledge of useful species.
Impact of Population, Building, War
There are also a number of non-agricultural side effects of modernization which either directly or indirectly contribute to genetic erosion in indigenous food crops. These include: population growth and its increased pressures on resources; disruption of ecosystems by construction, particularly multipurpose dams; the higher priority given industrialization; mining practices; and war, civil strife and political instability. Africa has also experienced a rapid growth of market gardens to meet the demands for fruits and vegetables of tourists, expatriate Europeans, and Africans who have travelled abroad. In the city markets and kiosks of Nairobi, for example, there are significantly more non-native vegetables on sale than indigenous ones. This has resulted in further neglect of indigenous African food crops. In various ways, modernization has taken its toll in the loss of genetic diversity.
To provide a more rigorous scientific understanding of the status of African crops and plants, UNU/INRA has launched a major research and training effort, aimed at identifying gaps in knowledge and developing ways to monitor the continent's plant genetic resources. Future training courses on germ plasm conservation are planned. Thus far, field surveys have been conducted during 1991-1992 in 16 African countries with financial support from the UN Development Programme. This exercise sought to determine the actual number of species involved, the extent of their domestication, methods of propagation, uses in food preparation and overall economic importance. Further field work is projected on questions of resource management, land tenure, and sustainability measures.
Little Indigenous Research
There are more than 300 examples of indigenous African food crops, edible plants and multi-use species. But only a few - notably sorghum, millet, yams and cowpeas - are the subject of serious research on the continent, by either the national or international agricultural institutes. Okra and oil palm get very limited attention. Certain of the indigenous legumes are in danger of extinction as are some of the tree crops; these have great potential in agro-forestry and other cropping systems that do less harm to the environment.
Less than a third of the 300 plus species that could provide food and other benefits are fully domesticated and under regular cultivation. It is only in domesticated plants under regular cultivation. The only way that agronomists and others can assess and isolate superior plants is through regular domestic cultivation. Charles Darwin was one of the early biologists to recognize that plant and animal variability often increases considerably under domestication. Where artificial selection has not been practised, genetic erosion will overtake both superior and inferior lines at the same rate, with no attempt made to conserve the superior examples.
Home Gardens: Do-it-yourself Labs
One important local centre of genetic diversity in Africa is the home garden; it has both nutritional and economic importance to the household. The garden also serves as an experimental site where farmers conduct their own on-farm experimentation with many individual plants.
Home garden species have multi-use potentials as sources of food, feed, fibre, and structural materials. A UNU/INRA field survey has reported that very little home garden planting information is being supplied by extension services to farmers.
The biodiversity of such plots is already under threat from various pressures of modernization pressures. As available space becomes choked out by ill-planned urban policies, the productivity of home gardens declines. A follow-up study will examine ways to design home gardens to minimize their competition with other urban needs.
Promoting Indigenous Foods
In various ways, UNU/INRA will be trying to encourage greater use of Africa's own indigenous crops in the daily diet, a step with both nutritional and economic benefits. INRA scientists will be collecting and evaluating useful indigenous African plants, with priority given to areas under threat of habitat destruction and species extinction. Facilities will be developed at INRA's main facilities at the Legon site of the University of Ghana for low-temperature seed storage banks and in vitro conservation of vegetatively propagated species. Seedbanks will also be located in individual countries for the conservation of germ plasm at the country level. Conservation possibilities are also being explored in selected concentrations of biodiversity - for example, in sacred forests and groves which have not been touched over the centuries.
Research is also planned on ways to stimulate more commercial use of indigenous crops and encourage their use in weaning foods, snacks and food for special occasions. At present, indigenous foods are rarely served in hotels and other commercial eating places. Efforts should also be devoted to improve these foods in a manner to make them more attractive to tourists and other hotel clients. Replacing imported foods would lessen the drain on foreign exchange, and thus could have significant impact on the hard-pressed economies of many African nations. But the INRA research has cautioned that appropriate priorities need to be established to ensure that economic and environmental interests both get a fair hearing in setting agricultural policies.
Training for Conservation
Training programmes are envisaged in three areas. The first is aimed at supporting the training of plant taxonomists in selected universities in both Francophone and Anglophone African countries through support for M.Sc. and Ph.D. courses and thesis-related work. This is a response to the disturbing present situation, where there are more taxonomists working on African plants outside than inside Africa. A second training effort will focus on germ plasm conservation, an area where the continent's resources are particularly weak. Finally, there will be development, in cooperation with UNESCO, of special courses, at the Bachelors, Masters and Ph.D. levels on the genetics and breeding of indigenous African plants.