Concern for the sustainable management of the world's forest resources has never been greater. Across the globe, numerous initiatives are under way to foment the development of forest management plans aimed at maximizing the contribution of forests to the achievement of development and socio-economic goals without compromising the present and future condition of the resource base. The discussion on sustainability tends to focus on the need to be environmentally "correct" while ensuring provision of adequate direct or indirect economic benefits to the owners or users of forest lands, thereby justifying their maintenance as forest as opposed to their permanent conversion to another form of land use.
Silviculture, as the element of forestry that deals with the establishment, development, reproduction, care and harvesting of forest vegetation, has the daunting yet essential responsibility of providing the biological and technical options to achieve management objectives. Without appropriate silviculture, sustainable forest management is impossible.
As such, it would seem logical for silviculture to be at the forefront of attention, both within and outside the forestry sector. Instead, in some instances silviculture seems to be taken for granted while, in others, it is virtually neglected.
Among some actors, particularly within the forestry sector, there is a tendency to affirm that the technical solutions to the challenges of sustainable forest management already exist and that it is only a matter of applying them appropriately. External actors, on the other hand, especially those with a protectionist perspective, often accuse silviculturists of not having the technical knowledge required to satisfy the new and multiple demands being made on forest resources without endangering the resource. They argue, therefore, that the forests should simply be reserved against further use until research has identified appropriate, widely applicable techniques, except perhaps for use by local people who are believed to have sufficient knowledge of their resource, at least in a micromanagement situation. These same actors often argue for "regreening", but without considering with what species, for what use and under what ecological conditions. This tack can only lead to forests that are without long-term biological or economic viability.
Both of the positions err on the side of extremity and yet both also hold elements of truth. Although tested appropriate techniques do exist for a limited number of forest situations, primarily in the temperate and boreal zones, silviculture in the tropics, particularly in terms of natural forest management, is still in its infancy. On the other hand, the suggestion that insufficient scientific knowledge prevents action is unacceptable; the absence of complete knowledge will not keep forest resources from being used or abused.
This issue of Unasylva examines how silviculturists are attempting to meet the challenges of today's rapidly evolving forest management objectives. In the first article, J.G. Bertault, B. Dupuy and H.F. Maître of the International Cooperation Centre on Agrarian Research for Development's Forest Management Program me (CIRAD- Forêt) examine silvicultural options available for the management of both natural and plantation forest formations in the humid tropics. They conclude that technical capacities are sufficient to support large-scale plantation activities but that the level of knowledge on the silvics of natural forest stands is still modest, although some effective practical tools have been developed. A short article by C. Linares Bensimon discusses the development of a silvicultural plan for the management of the Alexander von Humboldt National Forest, located in the Peruvian Amazon.
The challenges facing silviculture in the dry tropics are reviewed by M. Soto Flandez, based on his experiences as chief technical adviser for an FAO-assisted project in Burkina Faso. S. Hagner deals with silviculture in boreal forest areas, where harsh climatic conditions, high levels of industrial exploitation and the resource's concurrent importance to national and local economies combine to present special challenges.
As the demands on forests change and expand rapidly, silviculture must evolve as well. H. Benskin and L. Beford examine the changing demands on silviculture in British Columbia in response to new multiple objectives of forest management. They detail initiatives aimed at the basic stewardship of all valuables, investments to improve volume and value and the generation of employment. J. Kartasubrata and K.F. Wiersum explore the evolution of silvicultural research in Indonesia in response to changing forest management objectives. Particular emphasis is laid on the silvicultural challenges brought about by the recent focus on community forestry development, and on the need for field-level research combining scientific knowledge and the empirical expertise of local forest resource users. In the final article directly related to the main focus of this issue, M.Z. Hussain describes silvicultural systems for mangrove ecosystems that are being practiced in a number of countries in Asia and examines their potential application on a wider basis.
This issue of Unasylva also contains three highly stimulating, provocative independent articles: B.A. Wilcox discusses efforts to develop tools for assessing, quantitatively and qualitatively, the risks for biodiversity in the face of tropical forest loss and degradation; A. Agrawal re-examines the relative importance of population pressure, market forces and institutional effectiveness on forest conditions; and E. D'Souza describes the progressive involvement of the Indian military forces in environmental protection work.
