The principle of sustained yield is a concept that has developed over many decades of forest management and research. Most foresters are familiar with this concept and many attempts have been made to devise systems of forest management that follow sustained yield principles. More recently however, a broader concept of sustainable forest management has been introduced into the national and international policy debate about how forests should be managed. In contrast to sustained yield, sustainable forest management considers the sustainability of production of a wider range of forest outputs, rather than concentrating on one or two products (usually timber and, occasionally, non-wood forest products). There is currently still little agreement as to what exactly constitutes sustainable forest management, or how it should be achieved, although most commentators would probably agree that only a small proportion of the world's forest estate is currently managed in a way that is broadly sustainable.
It is against this background, that this paper has been commissioned by FAO on behalf of the World Bank to review and summarise current experiences with attempts to manage forests sustainably. Due to the difficulty noted above, it concentrates largely on attempts to manage forests for sustainable wood production, although it does also review what little information is available about forest management to meet other objectives. The paper only focuses on forests in tropical countries. Another paper in this series discusses progress towards sustainable forest management in temperate and boreal countries.
The paper is in eight main sections. The first two sections describe the extent of the tropical forest resource and discuss some of the issues that are currently being raised in the debate about sustainable forest management. The third section describes experiences from tropical countries around the world with sustained yield management and section four discusses forest management for objectives other than wood production. Sections five and six appraise experiences to date and discuss the scope for improving forest management in the future. Section seven makes recommendations about how forest management might be improved and the main findings of the report are summarised in section eight. A large number of very useful case-studies are presented in annexes to another version of this report, which is available in French as a separate paper.
This paper has been prepared by staff of CIRAD-Foret, drawing from the broad range of experiences of that organisation and a review of published materials. FAO would like to express its gratitude to all the contributors to this paper and to thank everyone that has provided comments on earlier drafts of this work. FAO will continue to explore, with member countries, the ways in which sustainable forest management can be implemented with greater success and to assist with implementation through its technical and normative work programmes. In this respect, we would welcome comments on all aspects of this study from readers.
Forestry Policy and Planning Division
There are several difficulties when trying to interpret sustainability in a technical or scientific sense. These largely relate to the backgrounds and views of the various parties involved in the current debate about sustainability. The major difficulties are highlighted below.
_ The first difficulty relates to the various objectives implicitly included in different definitions of sustainability. A clear statement of value-systems and objectives is necessary before any technical questions about sustainability can be answered. Only then can sustainability be properly translated into technical terms and used to develop a strategy to achieve such objectives.
_ The second difficulty stems from the analytical approach typically used to address problems of sustainability. Sustainable development is a global issue that needs to be addressed at a global level and by using knowledge and techniques from a number of disciplines. The challenge for sustainable forest management is to design and implement management systems that are both practical and multi-disciplinary in their approach to resolving forest management problems.
_ The third problem concerns the variety of different temporal and spatial scales over which sustainability can be measured. For example, global ecological changes such as the "greenhouse effect" occur at the largest scale but need to be addressed in operational terms at international, national, regional and local levels.
_ The fourth problem concerns the inherently long-time periods that have to be considered in forest management. Trees have lifespans varying from several to several hundred years. Consequently, successive cycles of management may cover several decades or a thousand years. In view of the time it takes for forests to respond to changes in management, it is necessary to both think and act with a view to the long-term. This perspective contrasts markedly with financial and economic techniques used in forest management that tend to focus on the short-term. It also suggests that a precautionary approach should be taken when considering the management of tropical forests.
In a very practical sense, sustainability also involves some major methodological and measurement problems, particularly in terms of assessing different silvicultural practices. It is no longer sufficient to only assess the impacts of forest management on the forest. It is also now necessary to consider the impacts of management in the long-term on other economic, social and environmental systems (e.g. agricultural productivity, climate, and hydrology).
This report only addresses technical questions about sustainable forest management and does not consider moral or socio-political issues (it would be more appropriate for specialists working in these areas to investigate such issues). In other words, the report covers the technical debate surrounding the sustainability of various forest management methods and systems, rather than the wider debate about the goals of management.
B Dupuy, H -F Maître and I Amsallem