The Effects of Deforestation on the Ecosystem

Easter Island is best known today for its enigmatic statues. It may also illustrate, however, the long-term ramifications of environmental mismanagement, according to the book "Essential Environment," by Scott Brennan and Jay Withgott. By studying pollen grains in mud cores and archaeological evidence, scientists found that the island may have been deforested over time by its inhabitants, leading to soil erosion that eventually undermined a once-proud civilization. Although the effects of deforestation aren't always so dramatic, deforestation can have serious and far-reaching consequences for the health of an ecosystem.

Habitat Destruction

• The most immediate consequence of deforestation is habitat destruction. Many different species of animals and plants live in forests, and the destruction of the forest eliminates their habitat, leaving them homeless. Birds such as woodpeckers may build nests and live in trees, for example, or shade-loving plants accustomed to moist soil may find themselves exposed to full sunlight and to rapidly drying soil. Organisms that are unable to compete or survive in these altered conditions may die, and other organisms that depended on these vanishing species for food may in turn also die. According to "Essential Environment," habitat destruction is a major contributor to extinction of wildlife.

Habitat Fragmentation

• Deforestation can sometimes leave forest-dwelling species confined to smaller and more scattered patches of habitat, a process called habitat fragmentation. Species such as mountain lions or bears that need large tracts of land may die out. The edge of these small patches of habitat can also be altered by interactions with different communities of species in the surrounding deforested areas, causing further species loss.

Soil Erosion

• Trees and other plants help to anchor soil in place with their roots. They also act as windbreaks to slow or curb wind erosion. With the loss of trees and plants, the soil may erode more rapidly, making it more difficult for plants to recolonize the land left vacant by deforestation. If the land is adjacent to a desert region, the loss of ground cover, increased evaporation and ensuing soil erosion can sometimes cause deforested land to degenerate into desert, a process called desertification.

Nutrient Loss

• In many tropical rain forests, the soil is actually nutrient-poor; warm, humid conditions encourage a high rate of decomposition, and nutrients from dead or decaying organisms are rapidly recycled. Most of the nutrients in the ecosystem are stored in the plants themselves rather than in the soil. According to "Essential Environment," when a tropical rain forest is clear-cut, the soil that remains is often nutrient-poor and thus difficult for farmers to exploit.