|Imperiled Riches—Threatened Rainforests|
A WORLD Imperiled: FORCES BEHIND FOREST LOSS
As the first seven sections of this site have described, tropical rainforests are incredibly rich ecosystems that play a fundamental role in the basic functioning of the planet. Rainforests are home to probably 50 percent of the world's species, making them an extensive library of biological and genetic resources. In addition, rainforests help maintain the climate by regulating atmospheric gases and stabilizing rainfall, protect against desertification, and provide numerous other ecological functions.
However, these precious systems are among the most threatened on the planet. Although the precise area is debated, each day at least 80,000 acres (32,300 ha) of forest disappear from Earth. At least another 80,000 acres (32,300 ha) of forest are degraded. Along with them, the planet loses as many as several hundred species to extinction, the vast majority of which have never been documented by science. As these forests fall, more carbon is added to the atmosphere, climactic conditions are further altered, and more topsoil is lost to erosion.
Despite increased awareness of the importance of these forests, deforestation rates have not slowed. Analysis of figures from the Food and Agriculture Organization of the United Nations (FAO) shows that tropical deforestation rates increased 8.5 percent from 2000-2005 when compared with the 1990s, while loss of primary forests may have expanded by 25 percent over the same period. Nigeria and Vietnam's rate of primary forest loss has doubled since the 1990s, while Peru's rate has tripled.
But enough about the extent and some of the effects of deforestation. What is responsible for this loss? This is the question this section addresses.
Deforestation and Degradation
Before expanding further on forest loss it is critical to first explain what is considered "forest" and what is meant by deforestation and forest degradation.
The Food and Agriculture Organization of the United Nations (FAO), the leading source for information on the status of the world's forests, defines forests as land with a tree canopy cover of more than 10 percent and an area of more than half a hectare. FAO says that "forest" includes natural forests and forest plantations but specifically excludes stands of trees established primarily for agricultural production (i.e. fruit tree and oil palm plantations) and trees planted in agroforestry systems.
Other organizations use different standards for defining forests. For example, the United Nations Environment Programme (UNEP) uses 40 percent cover as the threshold for "closed forests" and 10-40 percent cover for "open forests," while the Tropical Ecosystem Environment Observations by Satellite (TREES) project—funded in the 1990s by the European Commission—classifies areas with more than 70 percent canopy cover as "dense forests" and those with 40-70 percent cover as "fragmented forest."
To reduce confusion, this site will generally follow FAO's convention, even though it has been criticized for its generous definition of what it considers forest.
FAO defines deforestation as "the conversion of forest to another land use or the long-term reduction of the tree canopy cover below the minimum 10 percent threshold." Depletion of forest to tree crown cover greater than 10 percent (say from 90 percent to 12 percent) is considered forest degradation. Logging most often falls under the category of forest degradation and thus is not included in FAO deforestation statistics. For this reason, forest degradation rates are considerably higher than deforestation rates.
Digging a little deeper, FAO says that "deforestation includes areas of forest converted to agriculture, pasture, water reservoirs and urban areas," but the term "specifically excludes areas where the trees have been removed as a result of harvesting or logging and where the forest is expected to regenerate naturally or with the aid of silvicultural measures."
Deforestation vs. Degradation
[full photo version]
Continued: Natural forces behind deforestation
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