Posted June 1996
Forests, the biological diversity they contain and the ecological functions they have and help to maintain, are a boon to mankind. In both temperate and tropical zones the aim of forest conservation is to make rational use of land and resources on a sustainable basis, while satisfying the short-term needs of human populations.
The forest serves to moderate or regulate local and regional climate (temperature and rainfall) and to keep topsoil in a state suitable for cultivation. Its role in watershed behaviour is essential. Thus forests sustain the productive capacity of land and the availability of water for agriculture and for other uses (drinking water, hydropower, navigation). Forests provide a source of income, foreign exchange and employment opportunities through the harvesting and processing of wood. They also yield other products for local consumption and for export, including food, fodder, fuel, gums, resins, dyes, tannins, herbs and medicines. Wildlife represents another substantial economic resource with diverse uses, and the social value of the forest for recreation and community life is great, though difficult to quantify.
The major current problem is the extent and rate of destruction of forests. More than 11 million hectares of tropical forest were lost each year during the early 1980s when the annual reforestation rate was only 1.1 million hectares. The effects of deforestation and severe forest degradation are diverse and far reaching. Impacts are environmental, economic and social. Forests fulfill a number of environmental functions which are not yet fully understood in all their aspects. This makes it more difficult to manage them for sustainable economic and social use.
The major source of carbon dioxide release into the atmosphere is the combustion of fossil fuels. This accounts for approximately 6000 million tons of carbon a year. The amount of carbon dioxide released per year by burning of forest has been estimated at 1000 to 2000 million tons (0.27-0.55 metric tons of carbon). Fires in the savannahs of the world may release up to three times as much carbon dioxide as is discharged into the atmosphere by deforestation in the tropics.
Large quantities of carbon are absorbed by plants from the carbon dioxide in the air and are subsequently used to create biomass through the process of photosynthesis. Hence, maintaining sufficient, vigorously growing forested areas can help mitigate climate change. Forests deserve some credit for limiting the recent net increase of carbon in the atmosphere to about 3000 million tons annually. Large-scale industrial plantations, particularly those established on non-forest lands, are efficient in carbon dioxide capture, especially at higher growth rates. However, an increase in small-scale tree planting and trees in agriculture worldwide could probably more than rival industrial plantations in carbon dioxide capture capacity and have other positive effects.
Plentiful solar radiation and water supply ensure that tropical rain forests have a high primary production, about twice that of temperate forests. This high production is possible despite a common dearth of soil nutrients. Tropical forests are a reservoir of nutrients held mainly in the living vegetation rather than in the soil.
Deforestation frequently causes leaching of soil nutrients. The thin layer of topsoil may be washed away. Land degradation may occur at the deforestation site and often also farther away. Desertification may ultimately result. Agroforestry may be a means to maintain soil fertility in areas cleared mainly for non-forestry uses. In the drylands, windbreaks and shelterbelts are essential to protect cropland from wind-caused erosion, to maintain soil moisture and to lower evaporation losses.
Woody vegetation can also have a key role as a source of fodder and fuelwood in areas where erratic rainfall and drought are frequent. Silvopastoral management is therefore an important option for the rangelands where a pastoral and often nomadic type of economy is dominant.
Logging is the intentional, generally selective, removal of biomass from the forest. If properly managed, such harvesting will increase the value of the stand in the long run rather than degrade it. Unfortunately, because less than 5 percent of the productive tropical forest is being systematically managed, logging can lead to severe degradation of the stand. Degraded areas may subsequently be invaded by landless people who practise shifting cultivation or permanent agriculture, clearing the land by burning and changing its use. This often results first in deforested and later in barren lands. By providing access, logging can trigger such a change but it is not a direct cause of deforestation. Proper management, backed by policies and legislation, can do much to prevent the problem and sustain an important source of foreign exchange for many developing countries.
The degradation and destruction being wrought by "acid rain" especially in some areas of the northern hemisphere is one effect that has its cause at a distance from the ecosystem, principally in industrial energy use leading to emission of sulphur-containing gases into the atmosphere. Water pollution contributes to damage to riverine, swamp (mangrove) and coastal forests. Insect pests and diseases of the flora cause widespread damage in planted, more homogeneous forests where the protection afforded by diversity is reduced.The rate and extent of deforestation have given rise to concern that genetic resources of plants and animals living in or depending on the forest may gradually be depleted. Biological diversity and interaction between species, locally adapted races or variants are mainstays of balance in forest ecosystems. The genepools in these ecosystems are moreover a valuable and irreplaceable reserve of characteristics needed for improvement of domesticated plants and animals that provide food and other essential goods and services for people.
Availability or economic harvesting of products of the forest may be threatened by unplanned or careless destruction. For nationwide use and international trade, this can be detrimental for many developing countries with respect to wood products like roundwood logs, sawn timber, veneer and panels, pulp and paper. Serious consequences for local populations can arise with respect to supplies of honey, fruits, edible fungi, oils, meat and skins, gums, medicinal herbs and other forest products. Wildlife habitats can be seriously impaired by frequent forest and bush fires. Settlement schemes, for example for tsetse fly eradication, and poaching can endanger wildlife resources. Some species can be important for food and hides. Potential exists for systems combining certain wildlife with domesticated livestock, but the animal health aspects of mixed ranching need further study.
The capacity for effective application of science and technology is frequently weak in many developing countries. In part this limitation derives from a lack of detailed knowledge. Thus direction for research should come from reliable and comprehensive inventories and assessments made by national forestry organizations. Most technical problems are site-specific. Research findings at one location cannot be utilized at another without further adaptive research. Too often the social and economic setting in which improvements through application of science and technology were made was not sufficiently known or considered.
There is an urgent need to bring science and technology to bear in forestry, and particularly in tropical forestry. The Tropical Forests Action Programme is a policy and strategy statement and an overall philosophy promoted by FAO, UNDP, the World Bank and the World Resources Institute, and adopted by a great number of developing countries as well as the international community. One of the TFAP's important activities is the drive to increase forestry research, currently absorbing only about 5 percent or US$ 50 million of international resources devoted to tropical forest development. CGIAR has begun to sponsor additional forestry-related research in the context of activities in natural resources conservation and improvement.
There is no dearth of forestry problems awaiting scientists and technologists. One specific case is the need to conserve and improve the genetic resources of multipurpose trees and shrubs in semi-arid and arid zones. In these zones the degradation of the native vegetation and its genepools is proceeding at an accelerated pace just when improved planting material is urgently needed inter alia for local use as firewood and fodder, both of which are running short. Where land has become unproductive because of erosion or salinization, it can be rehabilitated by planting trees that are carefully chosen, established and managed. The new biotechniques can be used as tools in strategies elaborated to meet several needs, e.g. speedier multiplication of forest plants and improved breeding for resistance to abiotic and biotic stresses. Much scientific knowledge is required to develop appropriate, environmentally sound and sustainable technologies for harvesting and processing of forest products and for establishing suitable forest industries. Attention should also be given to the development of agroforestry systems by which sustainable crop production can be achieved while maintaining the forest ecosystem.
FAO's Forestry programme supports and supplements the TFAP in many areas and ways. An in-depth study of the roles of forests and forestry in global warming and climate change is giving guidance for action by FAO and others. Re-assessment of the world's forest resources is under way to provide a 1990 baseline for information and for a re-estimation of trends of deforestation, reforestation and afforestation derived from an FAO study in 1980. The new study will include data on woody biomass; on distribution by ecological zone of vegetation types and forest formations; on trees on non-forest land; and on forest degradation risk. Full use is made in this re-assessment of the advanced "Geographical Information Systems" (GIS) technology developed by FAO. Knowledge of forest genetic resources and their conservation and improvement is of utmost importance in the struggle against desertification and soil erosion, as well as for sand dune control, and for forest management, regeneration and planting. FAO supports efforts to increase and disseminate this knowledge, and to set and coordinate relevant policies through its Commission on Plant Genetic Resources and the FAO Panel of Experts on Forest Gene Resources. FAO has assisted the efforts of numerous developing countries with in situ conservation of plant genetic resources through scientific and technical information as well as through advice on policy and community action. In collaboration with national institutes, research has been done on tree population dynamics, taxonomy, breeding systems, phenology and the biological functioning of ecosystems and species in the dry and humid tropics and at high altitudes, and pilot in situ conservation areas have been established, managed and monitored.
Under a long-term FAO Project on Genetic Resources of Arid and Semi-Arid Zone Arboreal Species for the Improvement of Rural Living, with activities in more than 20 countries, genetic resources mainly of Acacia and Prosopis species are collected, distributed, evaluated and conserved in situ and ex situ. Over the past few years FAO has also coordinated a project on genetic resources of woody species in Sudano-Sahelian areas of Africa.
FAO receives guidance for its work in forestry from its Committee on Forestry, open to all member nations. It maintains strong links with forestry scientists and their organizations, notably through the International Union of Forest Research Organizations. It collaborates with several UN agencies and other groups with an interest in forest development and research. For example, representatives of FAO, Unesco, UNEP and the International Union for the Conservation of Nature (IUCN), in the Ecosystem Conservation Group are examining legal instruments for conservation of biodiversity in the context of a draft convention on the subject.
FAO participates in efforts to combat forest fires through the working party on forest economics and statistics of the European Forestry Commission and through the committee of "Silva Mediterranea" on Mediterranean forestry questions. This organization is the hub of research networks on forest fire management, multipurpose trees to combat desertification, silviculture of cedars and white pine, and the selection of stands for seed production. A major thrust of FAO's work is institution and capability building to help developing countries to know their problems better and to address them more effectively. Training and the provision of information on the science and technology of forestry are important elements of this thrust. Training courses are often run in cooperation with advanced institutions. For example courses on forest fire control and management are organized jointly with Spanish and French institutes.
Modern information-gathering technology, particularly satellite remote sensing, is linked to a computerized forest inventory data processing system adapted by FAO for assessment of forest resources. FAO issues an annual newsletter, Forest Genetic Resources Information, and technical handbooks and manuals on topics like seed collection and handling, seed insects, in situ and ex situ conservation of forest species, forest and mangrove management, harvesting and logging, and others. "Unasylva", the FAO quarterly journal devoted to all aspects of forestry, has a wide readership and a high reputation for the quality and usefulness of its contents.