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In the last five years there has been a virtual explosion of interest in agro-forestry. The concept has spread from a few anthropologists, foresters, and agricultural scientists to become a priority for a number of national and international agencies. As with any new and widespread term, there are any number of more or less congruent definitions. While we should not try to arbitrate this debate, the word "agro-forestry" is used here to encompass any agricultural system that combines trees with crops and/or animals, either spatially or sequentially. The concept has proved to be a very useful box in which to include examples as diverse as live fence posts, trees in pastures, taungya systems, and the high diversity farms and kitchen gardens found throughout the humid tropics.
Some people have tended to see agro-forestry systems as a panacea for all "marginal lands," and the agricultural ills of developing countries in particular. Certainly, there are a number of important ecological benefits that can result from including trees in a variety of cropping systems, but the net social, economic, and environmental benefits will not necessarily be higher simply because certain tree species are included in pastureland, cropland, or fallow. One must see agro-forestry systems as an alternative to the usual emphasis on monocultures and realize that they may be viable across the spectrum from low capital and low-input farming practices to high capital, high-input agricultural systems. In particular, there is an urgent need to devise and test agro-forestry systems that could be applied in areas already suffering from degradation.
Thus, those who use the term agro-forestry must find a balance between the promise of such integrated productive systems and the realistic assessment of costs and benefits from a humanistic, economic, and environmental point of view. However, the science of agro-forestry is at such an early stage and the diversity of agricultural systems so great that it may well be years before one can accurately assess what proportion of the land is actually better suited for agro-forestry practices than for monocultures. The possible combinations of trees and crops are virtually infinite, and, when one takes into account the variation with regard to spacing, fertilization, soil types, etc., one cannot help but feel daunted at the magnitude of unexplored space. At the very least there are the guideposts of traditional agricultural systems, and the information contained therein will provide valuable assistance in directing the first tentative steps.
It was against this background that the workshop on agro-forestry systems in the African humid tropics was convened. The initial stimulus came from both the United Nations University, which was planning a regional workshop in Africa as a follow-up to similar workshops in Latin America and South-East Asia, and the International Development Research Centre (IDRC), which was planning to bring together the scientists involved in its agro-forestry research projects in West Africa. These two organizations then contacted the International Council for Research in Agro-forestry in Nairobi (ICRAF), which agreed to serve as a co-sponsor, supporting additional participants. Similarly, contact was established with the Economic Commission for Africa, UN Environmental Programme,
FAO, Unesco, and the World Bank, and they each agreed to sponsor one or more participants. At the same time discussions were held with the University of Ibadan, the International Institute of Tropical Agriculture, and the Federal Department of Forestry, and these three institutions generously agreed to be the local co-sponsors for the workshop. While special thanks must be given to the International institute of Tropical Agriculture for providing the conference centre and accommodations, all three local cosponsors provided support critical to the success of the meeting.
Altogether there were more than 60 participants from 14 African countries and representatives from nine international organizations. The fact that so many scientists were able to come together and discuss agro-forestry is positive evidence of co-operation and interest in agro-forestry on both the national and international scale. Equally important was the exchange between English-speaking and French-speaking scientists, and the publication of these proceedings in both English and French should help to facilitate further contacts and exchanges.
The large number of participants meant that more than 30 papers were presented in three days, and this severely limited the time available for the three working groups as well as discussion within the plenary sessions. In this sense the proceedings are representative, as they include only a brief summary of the discussion after each group of papers. A separate account of the one-day field excursion was not included, as most of the material can be found in the papers. The time available for the working groups was only one afternoon, and the respective reports were discussed in a plenary session just before closing. Thus, these reports represent a consensus on the three topics of research, education and extension, and management of agro-forestry systems, rather than a set of specific recommendations.
The large amount of material presented created its own problem: how to keep the proceedings to a manageable size. It was therefore decided that material being published elsewhere or not directly relevant to the theme of agro-forestry in the African humid tropics would not be included, and some papers are presented only as abstracts or extended summaries. The papers by Peter Poschen and Madicke Niang in particular, which were concerned primarily with agro-forestry outside the African humid tropics, are presented in very abbreviated form.
In preparing the material for publication it was also necessary to rearrange the papers from the order in which they were presented at the meeting. Since clear-cut classifications are usually a figment of the imagination, a liberal licence was taken to establish five main headings. The first section, "Principles of Agro-forestry," includes five thought-provoking papers that are relevant to all discussions on agro-forestry. These are followed by seven papers that use various traditional agro-forestry systems in the African humid tropics as their starting point and then discuss the prospects for further development. The third group, of six papers, is devoted to taungya systems in Nigeria and three other West African countries. The ten papers that follow are grouped under the heading of "Current Agro-forestry Activities," and these present most of the research that has been carried out on a variety of tree, crop, and animal combinations in seven countries, ranging from Rwanda to Cameroon. The final set of papers includes four case studies from different countries, some of which are only presented as extended summaries, and two papers detailing the concern of FAO and UNEP with agro-forestry.
We are grateful also for the presence at the conference of Amy Chouinard of the IDRC Communications Division. Her editorial advice and assistance were essential to the publication of this manuscript.
While these proceedings are concerned primarily with agro-forestry in the African humid tropics, the conceptual points are relevant to other agro-forestry systems as well; even many of the specific papers will be of value to those working in the Neotropics or Asia. Of course, the tree, pasture, or crop species may not be relevant to sites in other areas, but the experimental design or concern with developing traditional systems may apply.
It is our sincere hope that the audience for these proceedings will be as broad as possible, for the great need is to inform scientists, planners, and government officials of the possibilities for agro-forestry, and these proceedings provide the essential conceptual and technical base for all those working in the field of land-use management.
Gilles Lessard
Associate Director, Forestry
International Development
Research Centre
Lee MacDonald
Programme Officer
Natural Resources Programme
United Nations University