Many of the world's forests, especially in the tropics
(the areas closer to the equator), are disappearing because
of increased pressure of more people using the land. Deforestation
is a problem because trees absorb carbon dioxide and release
oxygen, and forests provide habitats for many of the Earth’s
species.
Tropical deforestation occurs for a number of reasons,
including clearing land for agricultural purposes and
commercial logging.
Farmers in many tropical countries clear land to plant
crops by cutting down the trees in a small area and burning
the tree trunks. This process is called "Slash and
Burn." After the burned debris is cleared away, the
farmer plants his crops. The problem with this agricultural
practice is that the nutrients (chemicals that provide
nutrition for plants to grow) in a tropical forest are
mostly in the tree trunks, stems, branches, leaves, surface
roots and leaf litter, not deep down in the soil as needed
by most food crops.
After a few years, the small amount of nutrients available
are used up, the farmer's crops become less productive,
and then the farmer moves on to another patch of forest
to slash and burn. Farmers also clear land to graze cattle,
then must clear more land when the grass doesn't grow
after a few years because of the poor nutrient value of
the soil. Cattle and other livestock are very damaging
to forest soils because their sharp hooves dig into and
destroy the roots, and their weight compacts and hardens
the soil. Often these farmers are so poor, they must keep
on with this practice in order to survive.
Commercial logging can be more or less damaging to the
forest, depending on how it is done. Clear cutting is
the most damaging, because it takes down all of the trees.
However, selective logging can be almost as damaging although
it only takes the most valuable tree species. The heavy
logging trucks, bulldozers and other equipment can do
an enormous amount of damage to the surrounding forest
as the loggers build roads to get to and take out the
timber.
The Amazon region of Brazil has had a very large amount
of deforestation during the last part of the last century.
In the 1970s and 1980s, the Brazilian government encouraged
poor landless Brazilians to claim ownership of land in
the Amazon region by settling on it and farming it (even
though the land was not productive for farming). Because
of this, the rate of deforestation in the Brazilian Amazon
was 6200 square miles per year from 1978-1986. By 1988,
6%, or 90,000 square miles (the size of New England),
of the Brazilian Amazon had been cut down. As much as
230,000 square miles (the size of Texas) was affected
by the deforestation.
Tropical deforestation has long-range and possibly dangerous
consequences. Trees contain about 50% carbon. When trees
are cut down and burned, the carbon combines with oxygen
and is released into the atmosphere as carbon dioxide.
Carbon dioxide is one of the greenhouse gases that contribute
to global warming and climate change.
Tropical rain forests are an important part of the global
water cycle, which is also known as the global hydrologic
cycle. Evaporation and other processes from the trees
and plants in the tropics return large amounts of water
to the atmosphere, causing cooling, cloud formation and
precipitation (rain). When the forest is destroyed, the
cooling effect is taken away, cloud formation and precipitation
patterns can be affected, and the sun's energy can heat
the earth's surface more.
Tropical rain forests cover only 7% of the Earth's surface,
yet they are rich in biodiversity, containing over half
of Earth's plant and animal species. Many of the rain
forest species can only exist in a specific habitat, so
when that habitat is destroyed by deforestation the species
may become extinct. Some of the tropical plant species
are very important to medicine, and we may be losing species
that could lead to a cure for cancer or other serious
diseases.
Another bad effect of deforestation is that native Indian
people may lose their lands and have nowhere to go. Many
native peoples live off of the products of the forest,
and have no way of supporting themselves outside of the
forest.
Although the rate of deforestation in the Brazilian Amazon
has slowed since the 1970s and 1980s, tropical forests
around the world, including in Africa and Asia, are still
under threat of disappearing. In order to stop deforestation,
governments must develop better methods of farming and
commercial logging, and improve the living conditions
of the poor people often responsible for deforestation.
There are many organizations, such as The Rainforest Network,
that work very hard to preserve tropical forests. We need
to be aware of the serious problems in all areas of the
world and help find the solutions. |
