A rapidly expanding world population is making increasing inroads into forest lands. Yet every country in the world also depends on the goods and benefits provided by forests, which in the future will have to be met from an ever decreasing area.
Forest lands are urgently needed for three purposes: for new agriculture; for the production of timber and fuelwood; and for a whole range of environmental benefits (catchment protection, the preservation of genetic resources, wildlife conservation, amenity and pleasure). Unplanned clearing and exploitation of forests continues to lead to land degradation much faster than well planned development brings land into sustainable productive use - either for agriculture or forestry. There is also the spread of desert conditions and the degradation of mountain catchments. In addition, the speed of change is bringing new preoccupations about the loss of wild species and genetic diversity.
The mismanagement of forest lands and forest resources over centuries, mainly due to the need to provide land on which to grow food, has led to a situation where the forest is now in rapid retreat. The main aspects of the situation are: serious shortages in the supply of industrial wood; the catastrophic erosion and floods accompanying the stripping of forests from mountainous land - especially in the Andes and the Himalayas; the acute shortages of fuel wood in much of the developing world; the spread of desert conditions at an alarming rate in the arid and semi-arid regions of the world; and the many environmental effects of the destruction of tropical rain forests.
At the world level, forests have a direct and beneficial influence on all parts of the biosphere as a result of photosynthesis, heat capacity, conductivity and reflectivity, aero-dynamic roughness, influence on the water cycle, and emissivity in the infra-red band. They act as buffer zones between man-made ecosystems; and they represent half of the world's photosynthetic fixation of carbon from the atmosphere, with its concurrent release of oxygen. They serve as the source of wood and wood products, and they harbour valuable wild plant and animal species. At local levels, forests contribute to regulation of water catchment and release; protection of soil against erosion by wind and water and against other forms of soil degradation; protection of wildlife; recreational resources; and the improvement of living conditions both in and around human settlements through the control of nuisances such as noise and air pollution, improved aesthetics, psychological relief, provision of shade (particularly in the tropics), agricultural protection and improvement when introduced as shelter belts and windbreaks. Trees serve to moderate wind velocities and improve the micrometeorological and soil moisture conditions in adjacent fields.
Much of the history of humanity has consisted in driving back the boundaries of the forest – first for grazing land and shifting cultivation, then for permanent agriculture. Most of our present cultivated and inhabited lands have been derived from forest. In favourable sites – such as the deltas of the Mekong and Nile, or on the fertile volcanic soils of Java, the agricultural experiment has been successful. In unsuitable sites, on the other hand, it has led to land degradation; and in some cases, over-exploitation has been shown to cause catastrophic erosion and the collapse of civilizations, as that of the Mayans in Guatemala. For centuries, forests have been despoiled of desirable species, and this has sometimes led to the near-extermination of some varieties; the cedars of Lebanon and of Cyprus were an early and notorious example. Forest soils were thought of as only there to be cleared and tilled; timber, fuelwood, animals for meat and skins, and other forest produce were there to be harvested. The numerous environmental benefits – the moderation of local climates, clear and regular water, freedom from soil erosion, protection from avalanches, and abundant virginal surroundings – were part of the natural order of things and taken for granted. The values of forests only began to be appreciated when they had nearly disappeared. Greek foresters are only now working to undo the damage done in the 3rd century BC. Sustained management began in English woodlands in the Middle Ages when only sufficient woodlands were left to meet the needs of local markets. The Swiss forest law was passed in the late 19th century in response to the alarming effects of over-exploitation of the forests in the alpine valleys; at the much the same time, the incoming British administration began forest restoration in Cyprus as a reaction to the devastated state of the forest there. Each of these was a local reaction and confined to the forest values considered important at that place and time - timber supply, soil erosion, water, danger of avalanches.
The demand for wood continues to rise; world production of wood products, including fuelwood and charcoal as well as commercial timber products, is 36 per cent higher than in 1970. Wood remains the main and often the only source of energy for many people in large areas of the developing world. In Africa, where 90 per cent of the population depends on firewood and other biomass for energy, the production and consumption of firewood and charcoal doubled between 1970 and 1994 and is expected to rise by another 5 per cent by 2010 (FAO 1997a). Commercial wood production is still dominated by the developed world, though developing countries increased their share of industrial roundwood output from 17 per cent in 1970 to 33 per cent in 1994 (FAO 1997a). The industrial countries are largely self-sufficient in timber and pulp products, with the important exception of Japan. Wood in Europe is produced mainly from managed forests and plantations but logging from natural or virgin forests remains common in North America. The biggest projected demand for commercial wood will come from Asia, where demand is rising most rapidly but reserves are already inadequate.
Each year, 90 percent of wood extracted from native Australian forests (5 million tonnes) is turned into woodchips for paper and chipboard.
Africa's forests are being degraded by droughts, fuelwood extraction, civil wars and the refugees that result, untimely bush fires and the advance of agriculture. Over-exploitation has resulted in forests of critically low quality in many parts of the world. For example, only about 10 per cent of the remaining forests in parts of the Mekong basin are now commercially valuable (MRC/UNEP 1997) and changes in the structure and composition of large forest areas in Latin America have led to irreversible losses in biodiversity (WRI 1997).
Commercial logging by the top five producers in the Asia-Pacific region – China, India, Indonesia, Japan and Malaysia – produces more than 200 million m3 of roundwood annually (ASEAN 1997, and WRI, UNEP, UNDP and WB 1998). Forty per cent of Australia's forests have been cleared, and only about 25 per cent of the original forest estate in Australia remains relatively unaffected by clearing or harvesting (Commonwealth of Australia 1996). Many of the remaining forests in the Mekong basin countries have been logged so extensively that they are now of critically low quality. For example, only about 10 per cent of the remaining forests in the Lao People's Democratic Republic are commercially valuable (MRC/UNEP 1997a). Commercial logging in the larger Pacific Islands has been largely driven by offshore demand, particularly in Asia, and deforestation rates have recently approached 2 per cent in countries such as Samoa (Government of Western Samoa 1994).
It is no coincidence that the forests of all the countries with major crop failures in recent years due to droughts or floods – Bangladesh, Ethiopia, India, Pakistan, the Sahel countries – had been razed to the ground and had not been replaced by woody vegetational cover.