In recent years, the attention focused on challenges facing the tropical forests has intensified dramatically. However, nearly the totality of this attention has been directed toward the forests of the humid tropics. Even in technical documents, it is not uncommon to find statistics on the extent of tropical forests and the rates of loss or alteration followed by narrative that deals almost entirely with tropical rain forests. Much less - in fact, almost negligible - attention has been focused on the challenges of forest resource management in arid and semi-arid areas.
Yet the problem of dryland degradation is one of the most serious resource management problems facing the world today. Occupying about one-third of the world's land surface area, and supporting a population of more than 850 million - almost 20 percent of the world total - the drylands are rapidly being degraded through population growth, overgrazing, cropping of marginal lands, inappropriate irrigation and, not least, deforestation. In 1983 the United Nations Environment Programme assessed the implementation of the 1977 UN Plan of Action to Combat Desertification and found that at least 75 percent of the productive land in arid and semi-arid areas was already at least moderately decertified (having lost more than 25 percent of its original productivity). The problem is particularly serious in the developing regions, where degradation of rangelands and areas adjacent to the borders of semi-arid rain-fed farming areas continues to accelerate. Although croplands comprise only about 15 percent of the total dryland area, they are home to more than 85 percent of the dryland rural population, and the pressure is growing. Deforestation is intimately associated with dryland degradation as the destruction of woody vegetation for fuel and other uses far outstrips the rate of replanting and regrowth.
Trees and woody vegetation have a major role to play in the sustainable management of arid and semi-arid areas. Yet the multiple uses made of forest formations by local people over the course of centuries and even millennia - amply documented in an article on pastoralists' woodland management in Unasylva, 41(160) - have been poorly understood and inadequately developed both by foresters and natural resource managers in general.
In the late 1970s end early 1980s, forestry in arid zones tended to concentrate on the establishment of large-scale plantations of exotic species, aimed exclusively at timber or fuelwood production. To do this, large areas of the "useless brush" on which local people depended for fuel, food and fodder have been cleared. In the development of agricultural schemes or irrigation projects, natural tree formations have often been eliminated, leading to increased erosion and subsequent losses in productivity and shortened life spans of reservoirs. However, although the overall trend is still unsatisfactory, there is growing evidence of a change in thinking on the part of foresters and land-use managers concerned with arid zones. This issue of Unasylva evidences this change in perspective as well as the positive results that may be obtained as a consequence.
J. Fries and J. Heermans review a number of the major issues related to natural forest management in arid and semi-arid Africa, highlighting three promising efforts: one in the Niger and two in Burkina Faso. It is noteworthy that close cooperation with the local populations in planning and implementation is a common denominator. S. Guinko and L.J. Pasgo document the economic importance of edible forest products in a village of Burkina Faso, while F. Murindagomo examines the Zimbabwean CAMPFIRE programme, which is a wildlife management effort based on people's participation.
F.R. Bach focuses on the progress of a long-term FAO project, Genetic Resources of Arid/Semi-arid Zone Arboreal Species for the Improvement of Rural Living, as an example of a systematic approach to the conservation and enhancement of forest genetic resources. Under the project, 39 institutes in 26 countries are collaborating in the collection and assessment of the provenances of multipurpose arid-zone species. R.J. Vandenbeldt highlights the potential of agroforestry systems in the semi-arid tropics, including parklands, wind-breaks and silvipastoralism; but he cautions against the wholesale application of techniques developed for more humid areas.
Capitalizing on a wealth of documentation, this issue of Unasylva also offers two articles based on relevant papers prepared for the recent Tenth World Forestry Congress: A. Kowsar documents the effective results obtained with a simple, inexpensive water management system in Iran, based on floodwater spreading; and A. Babaev and N. Kharin discuss the use of trees and woody formations in desertification control in the USSR.
With this issue, Unasylva begins its second two-year cycle since resuming publication in January 1990. The many positive reactions to the eight issues of the "new" Unasylva are gratifying indeed (a selection of letters to the Editor appears on page 60). Yet we would take this opportunity to renew the invitation for our readers to take an even more active part in our continuing dialogue. The perspectives, comments and suggestions of forestry and natural resource decision-makers worldwide are an essential complement to the guidance of the Unasylva Editorial Advisory Board in ensuring the continued quality and relevance of the journal.