Agriculture in temperate regions has depended upon forest removal, capitalizing upon forest soil fertility. Most of England's woodlands were deforested by 1350. In continental Europe and North America, deforestation accelerated in the 18th and 19th centuries to clear land to grow food for industrial cities, and to meet fuel and construction needs. Rising agricultural productivity has since allowed much temperate farmland to revert to forest. From a low of 5 per cent in 1900, the United Kingdom's forest and woodland area is now around 10per cent. Tropical deforestation increased rapidly after 1950, helped by the availability of heavy machinery. Since then, rising human populations have also cleared forests the hard way—by hand. Annual rates of deforestation in 52 tropical countries nearly doubled from 1981 to 1990.
Slash-and-burn cultivation by small-scale is when small time Subsistence farmers clear forest to graze cattle and plant crops, they live of the land and when it becomes infertile due to over usage and grazing they move onto another part of the forest cutting down trees.
Timber harvesting is a significant cause of deforestation logging frequently damages more trees than it removes. Timber production in the Pacific Northwest of North America, and in Siberia, often replaces tree cover through plantation, or leaves the area to regenerate naturally through the process of succession, although soil degradation and erosion take place while the plant community is being re-established.
Clearance for settled agriculture, on infertile soils, results in short-term gains only. However, well-planned clearance has led to sustainable benefits, such as some rubber and oil palm plantations, which retain a forest-type structure aiding soil and water conservation.
Clearance for forest plantations, foresters worldwide have removed natural forests to make way for plantations that are higher-yielding in timber production. However, there is now more awareness among foresters of the social and environmental losses arising from this. Forest plantations, since they often contain single species of tree all of the same age, do not reproduce the ecosystem of the original forest, which is generally characterized by a wide variety of flora and fauna at all stages of development. Logging companies have been required since 1987 to replant all cleared land within five years; efforts are also made to retain the original diversity of tree species, although the animal and secondary plant ecosystems are necessarily affected.
Clearance for grazing was a major cause of deforestation in the 1970s and 1980s in Brazilian and Central American forests, with government-sponsored schemes to create large ranches. Regular woodland burning to maintain pasture is common in dry land Africa.
Clearance for fuel wood is a problem in the drier areas of Africa, the Himalayas, and the Andes.
Clearance for roads and dams has directly resulted in deforestation. Road development encourages timber exploitation, which opens the forest for agricultural settlement and fuel wood salvaging. About half of all logged tropical forests are eventually used for farming.
Afforestation, the planting of trees on land which did not previously have trees.The supply of wood and wood products from afforested areas has prevented the over-exploitation and destruction of our native forests. However, unwise planning and management of afforestation can lead to negative environmental impacts.
Trees absorb carbon dioxide (CO2) from the atmosphere during photosynthesis. It has been suggested that large-scale afforestation could successfully absorb the CO2 generated by the burning of the fossil fuels, coal and oil. The vast areas of afforestation required to achieve this would result in many negative environmental impacts. From a local perspective, in the short term such afforestation would cause as much environmental destruction as global warming could in the long term. A better approach would be to tackle this problem at its roots: reduce our reliance on fossil fuels and prevent deforestation of our natural forests. Fossil fuel combustion and deforestation together account for the majority of man-made CO2 releases.
The environmental implications of afforesting huge areas of land with coniferous monocultures first began to be appreciated in the 1960’s. Over the years it has become apparent that plantations could cause serious damage to the landscape, nature conservation, water and soil quality. Many of the problems stem from the fact that the plantations are even aged monocultures consisting of an exotic species.
Habitats most severely affected by afforestation include wetlands, grassland and native forests. Good management, and planning that takes conservation of natural habitats into consideration, can overcome these problems:
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Wetlands Plantations situated too close to wetlands and perennial streams, or in their catchments, leads to their eventual drying out as trees use large amounts of water.
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Grasslands These rich communities support a variety of animals, including threatened species. Afforestation converts grasslands to plantations, and so these animals lose their homes.
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Native forests When plantations next to native forests are logged, trees may fall onto the forest margin and damage it. Once damaged, the forest margin can no longer protect the native forest from fire. In addition, logging can destroy the diverse habitat where forest and grassland meet. The forest margin is an important food source for many forest animals, damaging this can endanger these organisms exsistence.
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River catchments Trees use large amounts of water. Afforestation in water catchments thus reduces runoff and water availability for other uses.
