EROSION AND ITS EFFECTS
The loss of trees, which anchor the soil with their roots, causes widespread erosion throughout the tropics. Only a minority of areas have good soils, which after clearing are quickly washed away by the heavy rains. Thus crop yields decline and the people must spend income to import foreign fertilizers or clear additional forest. Costa Rica loses about 860 million tons of valuable topsoil every year, while the Great Red Island, Madagascar, loses so much soil to erosion (400 tons/ha) that its rivers run blood-red, staining the surrounding Indian Ocean. Astronauts have remarked that it looks like Madagascar is bleeding to death, an apt description of a country with grave environmental degradation and an ever-declining agricultural economy that depends on its soils. The rate of increase for soil loss after forest clearing is astonishing; a study in Ivory Coast (Cote d'Ivoire) found that forested slope areas lost 0.03 tons of soil per year per hectare; cultivated slopes annually lost 90 tons per hectare, while bare slopes lost 138 tons per hectare.
Besides damaging the fisheries industry, deforestation-induced erosion destroys infrastructure of roads and highways that cross through the forest. The government does not shut down the roads, but must rebuild them repeatedly, using money that could be used more productively elsewhere.
Erosion is extremely costly for developing countries. Besides the damage to infrastructure, fisheries, and property, erosion of precious topsoils costs tens of billions of dollars worldwide each year. For example, in the late 1980s the Indonesian island of Java was losing 770 million metric tons of topsoil every year at an estimated cost of 1.5 million tons of rice, enough to fulfill the needs of 11.5-15 million people.
Environmental deterioration can leave people as "environmental refugees"—people who are displaced due to environmental degradation. The United Nations says that as many as 50 million people could be considered environmental refugees by 2010 due to deforestation, sea-level rise, expanding deserts, and catastrophic weather events. Red Cross research shows more people are now displaced by environmental disasters than by war.
[full photo version]
Continued: Species Loss, Extinction and Disease
Bibliographic citation for this page
Other pages in this section:
|what's new | rainforests home | help support the site | madagascar | search | about | contact|
Copyright Rhett Butler 1994-2005