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Deforestation is the
permanent destruction of indigenous forests and woodlands. The term
does not include the removal of industrial forests such as
plantations of gums or pines. Deforestation has resulted in the
reduction of indigenous forests to four-fifths of their
pre-agricultural area. Indigenous forests now cover 21% of the
earth's land surface.
FORESTS AND WOODLANDS?
In a forest the
crowns of individual trees touch to form a single canopy. In a
woodland, trees grow far apart, so that the canopy is open.
Of great concern is the rate at which
deforestation is occurring. Almost all of this deforestation
occurs in the moist forests and open woodlands of the tropics. At
this rate all moist tropical forest could be lost by the year 2050,
except for isolated areas in Amazonia, the Zaire basin, as well as a
few protected areas within reserves and parks. Some countries such
as Ivory Coast, Nigeria, Costa Rica, and Sri Lanka are likely to
lose all their tropical forests by the year 2010 if no conservation
steps are taken. In the United States almost all Virgin Forest
has been logged. We need to protect more woodlands and
develop them back into Forests.
HOW DOES IT HAPPEN?
Deforestation is brought about by
* conversion of forests and woodlands
to agricultural land to feed growing numbers of people;
* development of cash crops and cattle
ranching, both of which earn money for tropical
* commercial logging (which supplies
the world market with woods such as meranti, teak, mahogany and
ebony) destroys trees as well as opening up forests for
* felling of trees for firewood and
building material; the heavy lopping of foliage for fodder; and
heavy browsing of saplings by domestic animals like
To compound the problem, the poor
soils of the humid tropics do not support agriculture for long. Thus
people are often forced to move on and clear more forests in order
to maintain production.
While short-sighted, market-driven forestry practices are often one of the
leading cause of forest degradation, the principal human-related
causes of deforestation are agriculture and livestock grazing, urban
sprawl, and mining and petroleum extraction. Causes include demand
for farm land and fuel wood. Underlining causes include poverty,
lack of reform.
* Alteration of local and global
climates through disruption of:
a) The carbon cycle. Forests act as a
major carbon store because carbon dioxide (CO2) is taken up from the
atmosphere and used to produce the carbohydrates, fats, and proteins
that make up the tree. When forests are cleared, and the trees are
either burnt or rot, this carbon is released as CO2. This leads to
an increase in the atmospheric CO2 concentration. CO2 is the major
contributor to the greenhouse effect. It is estimated that
deforestation contributes one-third of all CO2 releases caused by
b) The water cycle. Trees draw ground
water up through their roots and release it into the atmosphere
(transpiration). In Amazonia over half of all the water circulating
through the region's ecosystem remains within the plants. With
removal of part of the forest, the region cannot hold as much water.
The effect of this could be a drier climate.
erosion - With the loss of a protective cover
of vegetation more soil is lost.
Silting of water courses, lakes and dams -
This occurs as a result of soil erosion.
species which depend on the forest for
survival. Forests contain more than half of all species on our
planet - as the habitat of these species is destroyed, so the number
of species declines (see Enviro Facts "Biodiversity").
The causes of desertification are complex, but deforestation
is one of the contributing factors.