Giant trees in rainforests all over the world are threatened not only by direct cutting, but also fire, pollution, and other factors. (Note the relative size of the two people sitting on this tree trunk!) Photo credit Corel Photo Clipart CD.

Deforestation conjures up images of acres of land, barren and bleak. So when someone sees the "highly deforested" areas in parts of the tropics, they are surprised and puzzled to see that there are many trees still there. In fact, it does not look deforested at all. The reason for this is because in these tropical forests, at least 10 percent of the land is covered by the crowns of the trees or bamboo. When the percentage of forest falls below 10 percent, tropical areas are considered deforested.

Rainforest is cleared for agriculture and houses in many areas, but not to an extent great enough to be called deforestation. Photo courtesy Naomi Woods.

But just because some trees can be seen does not mean that the forest is not being damaged. Any reduction in the forest is a problem for its ecosystem. Deforestation occurs when the forests are turned into farms to feed people or converted into cash crops or used for raising livestock. Also, logging trees for commercial use or for firewood leads to the destruction of the forests and to their use as land for agriculture.

Deforestation isn't just about a loss of trees. It also has a large impact on the environment. Many living creatures depend on the trees, so when the trees disappear, the animals die off as well (decreased biodiversity). Potentially valuable medicines and materials are lost, as well as clean water and air. Indigenous peoples suffer, and eventually national economies suffer too. The futures of people and forests are still interconnected.

Above and Top: Suburbs have expanded into areas that were once covered with forests, and the trees are now confined to small patches between fields, roads and buildings. Photo by Maya Walters.

Trees also store water and then release it into the atmosphere (this process is called transpiration). This water cycle is an important part of the ecosystem because many plants and animals depend on the water that the trees help to store. When the trees are cut down, there is nothing to hold the water, leading to a drier climate. Also, the loss of trees causes erosion because there are no roots holding the soil together. The dirt then washes away into lakes and rivers, killing the animals in the water.

One of the greatest causes of deforestation is overcutting. Almost anywhere that trees are logged, there are cases where too many are cut at once, making it almost impossible for the forest to grow back to its natural state. find out more...

Deforestation leads to the increase of carbon dioxide in the air because living trees store CO2* in their fibers, but when they are cut down, the carbon is released back into the atmosphere. CO2 is a major greenhouse gas, so cutting down trees contributes to the danger of climate change.

Riparian zones* are especially sensitive to the effects of deforestation. Roads and cut areas intercept or divert the natural flow of water, and can cause flooding, mudslides and siltation. This can lead to a loss of water quality and a loss of fish habitat and spawning areas. Many cities have been built around rivers, destroying the forest cover around these water sources. Photo by Maya Walters.

Unfortunately, developing countries in the tropics are trying to improve their economies by utilizing their forests. Brazil has flooded thousands of square kilometers of Amazonian forest for hydro-electric dams, and more are planned.

Large populations of very poor people and tropical forests produce conflicts. A subsistence farmer can't stop to worry about the environment. But the industrialized nations of the north also destroy large tracts of forest for short-term economic gain. A close up aerial view of a recently deforested area in Guatemala. Photo courtesy of Dana Slaymaker

Perhaps the greatest potential cause of deforestation lies in the future: climate change. If the greenhouse effect raises the earth's temperature, forests may no longer be able to survive in their present locations. Some may have to migrate up mountain slopes, or to cooler or wetter environments. But unlike conditions following the last Ice Age, global warming will probably happen too quickly for forests to adapt.