Deforestation

Deforestation is the conversion of forested areas to non-forest. Generally this involves the removal or destruction of significant areas of forest cover. Deforestation is an important aspect of habitat destruction.

Deforestation (whether deliberate or unintended) is the result of the removal of trees without sufficient reforestation. There are many causes, ranging from extremely slow forest degradation to sudden and catastrophic wildfires. Deforestation can be the result of the deliberate removal of forest cover for agriculture or urban development, or it can be an unintentional consequence of uncontrolled grazing (which can prevent the natural regeneration of young trees). The combined effect of grazing and fires can be a major cause of deforestation in dry areas. In addition to the direct effects brought about by forest removal, indirect effects caused by edge effects and habitat fragmentation can greatly magnify the impacts of deforestation.

While tropical rainforest deforestation has attracted most attention, tropical dry forests are being lost at a substantially higher rate.

Impact of deforestation

The impact of deforestation is best understood in terms of the benefits lost when forests are removed. Forests support considerable biodiversity. Forests are valuable habitat for wildlife. Direct economic benefits accrue from the harvest of forest resources such as wildlife, non-wood products like wild mushrooms and medicinal herbs and from the sale of hunting and camping equipment. Forests also play an important role in watershed protection, soil conservation and the recharge of aquifers. They can also be the source of new drugs (like taxol).

Although timber production can be an important cause of deforestation, higher long-term gains can be obtained by managing forest lands to maintain forest cover. Forests are also important stores of organic carbon, and forests can extract carbon dioxide and pollutants from the air. Forests are also valued as a thing of aesthetic beauty and as a cultural resource. Deforestation results in the loss of these benefits.

Definition of deforestation

There is no universally accepted definition of deforestation. Various governments and organizations use different definitions. The replacement of natural forests by plantations may be classified as reforestation by government agencies, but classified as deforestation by conservation groups. Deforestation can be defined broadly to include not only converstion to non-forest, but also degradation that reduces forest quality – the density and structure of the trees, the ecological services supplied, the biomass of plants and animals, the species diversity and the genetic diversity. Narrow definitions of deforestation define deforestation as the removal of forest cover to an extent that allows for alternative land use. The United Nations Research Institute for Social Development (UNRISD) uses a broad definition of deforestation, while the Food and Agriculture Organization of the UN (FAO) uses a narrow definition.

Definitions can also be grouped as those which refer to changes in land cover and those which refer to changes in land use.

Land cover measurements often use a percent of cover to determine deforestation. This type of definition has the advantage in that large areas can be easily measured, for example from satellite photos. A forest cover removal of 90% may still be considered forest in some cases. Under this definition areas that may have few values of a natural forest such as plantations and even urban or suburban areas may be considered forest.

Land use definitions measure deforestation by a change in land use. This definition may consider areas to be forest that are not commonly considered as such. An area can be lacking trees but still considered a forest. It may be a land designated for afforestation or an area designated administratively as forest.

Related terms are forest decline, forest fragmentation and forest degradation.

Causes of deforestation

Agents

Agents of deforestation can be individuals or groups of individuals that are clearing the forest. Commercial farmers, slash and burn farmers, cattle ranches and loggers are all agents of deforestation. Agents are usually acting in their own self interest.

Causes

Causes include demand for farm land and fuel wood. Underlining causes include poverty, lack of land reform. The causes of deforestation are complex and change over time. Deforestation can be most easily be understood by studying the causes for each forest and country separately.

Theories of deforestation

Three schools of thought exist with regards to the causes of deforestation – the Impoverishment school, which believes that the major cause of deforestation is "the growing number of poor", the Neoclassical school which believes that the major cause is "open-access property rights" and the Political-ecology school which believes that the major cause of deforestation is that the "capitalist investors crowd out peasants". The Impoverishment school sees smallholders as the principal agents of deforestation, the Neoclassical school sees various agents, and the Political-ecology school sees capitalist entrepreneurs as the major agents of deforestation.

History

Deforestation has been practiced by humans for thousands of years. Fire was probably the first tool that allowed humans to modify the landscape. The first evidence of deforestation shows up in the Mesolithic. Fire was probably used to drive game into more accessible areas. With the advent of agriculture fire became the prime tool to clear land for crops. In Europe there is little solid evidence before 5000 BP. Mesolithic foragers used fire to create openings for red deer and wild boar. In Britain shade tolerant species like oak and ash are replaced in the pollen record by hazels, brambles, grasses and nettles. Removal of the forests led to decreased transpiration resulting in the formation of upland peat bogs. Widespread decreased in elm pollen across Europe between 6400–6300 BP and 5200–5000 BP, starting in southern Europe and gradually moving north to Britain, may represent land clearing by fire at the onset of Neolithic agriculture.

Growing worldwide demand for wood to be used for fire wood or in construction, paper and furniture – as well as clearing land for commercial and industrial development (including road construction) has combined with growing local populations and their demands for agricultural expansion and wood fuel to endanger ever larger forest areas.

Recent change

The rate of clearance increased during the second half of the 19th century due to agricultural expansion in Europe. Deforestation rates peaked in New England about 1900 and in the Great Lakes region of the United States in the late 19th century. Rates of tropical deforestation have increased substantially into the post-war period as logging operations became mechanised.

Agricultural development schemes in Mexico, Brazil and Indonesia moved large populations into the rainforest zone, further increasing deforestation rates. One fifth of the world's tropical rainforest was destroyed between 1960 and 1990. Estimates of deforestation of tropical forest for the 1990s range from ca. 55,630 km² to ca. 120,000 km² each year. At this rate, all tropical forests may be gone by the year 2090.

Environmental effects

Atmospheric Pollution

Deforestation is often cited as one of the major causes of the enhanced greenhouse effect. Trees and other plants remove carbon (in the form of carbon dioxide) from the atmosphere during the process of photosynthesis. Both the decay and burning of wood releases this stored carbon back to the atmosphere.

Landslides

Tree roots bind soil together and act to keep the soil in place. Tree removal on steep slopes is often followed by an increase in landslide frequency.

Soil erosion

Deforestation promotes erosion of soil. Under normal circumstances trees and bushes and the forest floor act as a "sponge" for rainfall, slowing its overland and underground flow and releasing it back into the atmosphere through transpiration. Without the buffering effect of forest cover, rain impacting bare soil runs off faster and in greater quantities, carrying away topsoil and more often causing flooding. In this environment, nutrients in the soil are leached off and the microorganisms that can replenish these nutrients are disturbed.

Wildlife

Some forests are rich in biological diversity. Deforestation can cause the destruction of the habitats that support this biological diversity – thus causing population shifts and extinctions

Alternatives

An alternative deforestation for the purpose of timber is to build houses out of non-wood materials, such as brick, stone, concrete, and fiberglass. These materials have the additional benefits of being fireproof, waterproof, and pest-proof. Furthermore paper products can be made of hemp fiber instead of wood – although there are strong arguments stating that farming trees may create more forests than farming hemp.

Recycling paper reduces the number of trees cut down. E-mails and web pages may also reduce the amount of wood paper used. Some lumber companies are planting trees to replace the trees taken. Hay, dry weeds, trash, garbage, husks, and stalks can be burned for energy instead of wood, although this still causes air pollution.

Farming

New methods are being developed to farm more food crops on less farm land, such as high-yield hybrid crops, greenhouses, autonomous building gardens, and hydroponics. The reduced farm land means less land is cleared for growing crops. In cyclical agriculture, cattle are grazed on farm land that is resting and rejuvenating. Cyclical agriculture prevents the soil from being overfarmed and stripped of its nutrients – reducing the need for slash-and-burn methods.

Grass is allowed to grow on the resting farm land. The cows eat the grass and leave behind their dung, which is also a source of fertilizer. This process also reduces deforestation by using farmland to graze instead of using forest land.

Social change

Some societies are making efforts to stop or slow deforestation. In China, where large scale destruction of forests has occurred, each citizen must plant at least 11 trees every year. In western countries, increasing consumer demand for wood products that have been produced and harvested in a sustainable manner are causing forest landowners and forest industries to become increasingly accountable for their forest management and timber harvesting practices.

The Arbor Day Foundation's Rain Forest Rescue program is a charity that helps to prevent deforestation. The charity uses donated money to buy up and preserve rainforest land before the lumber companies can buy it. The Arbor Day Foundation then protects the land from deforestation. This also preserves the way of life of the primitive tribes living on the forest land.

See also

• desertification
• forestry
• Illegal logging
• overpopulation

References

• Whitney, Gordon G. 1996. From Coastal Wilderness to Fruited Plain : A History of Environmental Change in Temperate North America from 1500 to the Present. Cambridge University Press. ISBN 052157658X
• Williams, Michael. 2003. Deforesting the Earth. University of Chicago Press, Chicago. ISBN 0226899268
• Wunder, Sven. 2000. The Economics of Deforestation: The Example of Ecuador. Macmillan Press, London. ISBN 0333731468

External links

• FAO Forestry
• CFAN – CIDA Forestry Advisory Network
• Mongabay.com