Many human activities - from livestock raising to mining to military conflict - can lead to the degradation of forests and ecosystems. Responses on the part of governments, industry, international agencies and local communities have been directed to undoing or lessening the damage. This issue of Unasylva focuses on the techniques, but also the policy and social aspects, of rehabilitating particular degraded sites through forestry.
The issue opens with three articles on rehabilitation of different kinds of mining sites in different parts of the world. J. Gardner describes mining industry efforts to rehabilitate bauxite mines in Western Australia since the mid-1960s. Today's rehabilitation objective reflects an attempt to restore multiple land use values and species richness - and the successes obtained in a relatively short time can be seen clearly on our cover.
J.J. Griffith and T.J. Toy use the example of revegetation of open-pit iron-ore mines in Minas Gerais state, Brazil, to illustrate the evolution of corporate reclamation practices from the 1970s to the present. The article emphasizes the importance of a political and policy framework for environmental rehabilitation.
In New Caledonia, public opinion has played an important part in pressing nickel mining companies to take environmental action. As described by J.M. Sarrailh and N. Ayrault, rehabilitation of open-pit mines is as yet carried out on a relatively small scale, but awareness is growing. Where government or industry has not yet responded to the need, local communities have taken on reforestation efforts.
On steep slopes of New Zealand's North Island, a century of heavy sheep and cattle farming led to severe erosion. In the fourth article, D. Rhodes describes government reforestation efforts, which, in addition to providing soil stability, have produced socio-economic benefits in terms of wood supply, increased employment opportunities and reduced out-migration.
As a result of drought in Mauritania in the 1970s and 1980s, pastoral nomads settled along the main road crossing the country from west to east, known as the Road of Hope. The consequent degradation of woody cover resulted in mobilization of sand dunes, and the road became sanded for much of its length. An FAO project carried out plantings to stabilize the dunes - yet, as pointed out by A.M. Jensen and M.S. Hajej, some of the results have not lasted because of lack of maintenance.
For some forms of forest degradation there are no ready solutions. When a reactor at the Chernobyl Nuclear Power Plant exploded in April 1986, more than 4 million hectares of forest in Belarus, the Ukraine and the Russian Federation were contaminated with radiation. V.A. Ipatyev describes investigations in Belarus into means of decreasing the dangers of these forest stands, stressing the need for increased research.
Another problem leading to forest degradation, particularly in industrialized and industrializing countries, is airborne pollution. In the 1970s and 1980s, acid atmospheric deposition, together with inappropriate forestry practices, damaged the watersheds of the Jizera Mountains in northern Bohemia, Czech Republic. Soil erosion resulted in deterioration of the water quality and the extinction of fish in reservoirs. The article by J. Køeèek and Z. Hoøická describes how water quality has recovered in the past decade through a combination of decreased air pollution, harvesting to reduce leaf area and the use of deep-rooting native species.
The last two articles concern sites in Asia degraded at least in part through military action. T. Marghescu describes lessons learned from an FAO project to reforest highlands at Khao Kho, Thailand, denuded through insurgency, influx of migrants and overexploitation for unsustainable agriculture starting in the 1960s. One lesson of the project was that by attending to the land use and employment needs of the people in the area, pressure on degraded lands could be reduced, paving the way for successful natural regeneration.
Finally, P.N. Hong summarizes efforts to restore mangroves killed by the use of herbicides and defoliators during the Viet Nam war. Because of their importance to local people for food (fish and shellfish), timber and fuelwood, protection and management is critical to maintain the restored mangroves.
Successful rehabilitation of degraded sites depends not only on the development of appropriate techniques and learning from experience, but also on such factors as public environmental awareness, an enabling political and policy framework and the consideration of local needs. Those involved in rehabilitation projects have increasingly come to recognize the importance of using indigenous species, for example, not only for environmental reasons but also to meet the livelihood and cultural needs of local communities who may depend on forest products and services.
Frequently, projects to restore degraded sites are only part of the battle. Where natural or human impacts continue to threaten the environment, then the maintenance or continued expansion of reforestation efforts, or the protection of restored forest or tree cover, is often necessary to prevent a return to degraded conditions. Equally important are efforts to ensure that activites such as mining, industry and livestock grazing be carried out in a less environmentally damaging manner in the first place.
