| Much of the human-caused forest destruction stems from overpopulation. In many places, there are too many people trying to make a living from too few forest resources. Trees are cleared not only for wood and other products, but so that the land they once grew on can be turned into pastures for cattle and agricultural fields to feed growing numbers of people. As cities expand, forests are cleared to make room for housing developments, shopping malls, golf courses, and other structures that require large amounts of land. |
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As populations rise, cities expand into new areas which were once covered in trees. Photo by Maya Walters. |
| Other threats to the health of forests are more indirect. In certain areas, including much of Europe and the eastern United States and Canada, forests are declining because of air pollution. This pollution is from the fossil fuels burned in vehicles -- cars, trucks, buses -- and from industry. Carbon dioxide (C02), a gas which contributes to "global warming", is a well known emission from these sources, but vehicles and industry also produce sulphur dioxide and nitrous oxide gases, which create acid rain. Acid deposits can kill trees directly by leaching nutrients from them, resulting in the death of leaves and needles. The most damage, however, is caused when acid gets into the soil and releases poisonous heavy metals, which are naturally present but usually inaccessible. At the same time as the acid rain releases these poisons, it also dissolves and washes away vital nutrients in the soil. |
threats to forests -- page 3 of 6
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sub-topics
[deforestation] [climate change] [loss of biodiversity] [pollution] [erosion] [fire]
related topics
[wood & forest products] [climate] [water] [soil]
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