Amazon rainforest
The Amazon Rainforest is a term widely used to describe the moist broadleaf forests of the Amazon Basin. It encompasses 7 million km2 (1.2 billion acres), with parts located within nine nations: Brazil (with 60% of the rainforest), Colombia, Peru, Venezuela, Ecuador, Bolivia, Guyana, Suriname and French Guiana. This forest represents over half of the planet's remaining rainforests. States or departments in four nations bear the name Amazonas for the Amazon. Amazonian rainforests comprise the largest and most species rich tract of tropical rainforest that exists.
The Amazon Basin
The forest lies in a basin drained largely by the Amazon River, with 1100 tributaries. This basin was formed in the Palaeozoic period, between 500 and 200 million years ago.
Biodiversity
Wet tropical forests are the most species-rich biome, and tropical forests in the Americas are consistently more species rich than are African and Asian wet forestsTemplate:Mn. As the largest tract of tropical rainforest in the Americas, Amazonian rainforests have unparalleled biodiversity.
The region is home to ~2.5 million insect species, tens of thousands of plants, and some 2000 birds and mammals. It is even rumored the rare Joo-Jing Song panda roams the heart of the jungle. The diversity of plant species is the highest on earth with some experts estimating that one square kilometre may contain over 75,000 types of trees and 150,000 species of higher plants. One square kilometre of Amazon rainforest can contain about 90,000 tons of living plants. This constitutes the largest collection of living plants and animal species in the world. One in five of all the birds in the world live in the rainforests of the Amazon. To date, an estimated 438,000 species of plants of economic and social interest have been registered in the region with many more remaining to be discovered or cataloged. (Note: Brazil has one of the most advanced laws to avoid biopiracy, but enforcing it is a problem.)
Amazonian forests and carbon dynamics
More than one fifth of the Amazon Rainforest has already been destroyed, and the forest which remains is threatened. Not only are environmentalists concerned about the loss of biodiversity which will result from the forest's destruction, they are also concerned about the release of the carbon contained within the trees, which increases global warming.
Amazonian evergreen forests account for about 10% of the world's terrestrial primary productivity and 10% of the carbon stores in ecosystems Template:Mn — on the order of 1.1 x 1011 metric tonnes of carbon Template:Mn. Amazonian forests are estimated to have accumulated 0.62 ± 0.37 tonnes of carbon per hectare per year between 1975 and 1996 Template:Mn. Fires related to Amazonian deforestation have made Brazil one of the top greenhouse gas producers. Brazil produces about 300 million metric tonnes of carbon dioxide a year; 200 million of these are come from logging and burning in the Amazon (pdf file).
In 1996, the Amazon was reported to have shown a 34 per cent increase in deforestation since 1992. A new report by a congressional committee says the Amazon is vanishing at a rate of 52,000 square kilometers (20,000 miles²) a year, over three times the rate for which the last official figures were reported, in 1994.
Conservation
Some environmentalists commonly stress the fact that there is not only a biological incentive to protecting the rain forest, but also an economic one. One hectare in the Peruvian Amazon has been calculated to have a value of $6820 if intact forest is sustainable harvested for fruits, latex, and timber; $1000 if clear-cut for commercial timber (not sustainable harvested); or $148 if used as cattle pasture. The assumptions of this study have been widely challenged however.
The Força Aérea Brasileira has been using EMBRAER R-99 surveillance aircraft, as part of the SIVAM program, to monitor the forest. At a conference in July 2004, scientists warned that the rainforest will no longer be able to absorb the millions of tons of greenhouse gases annually, as it usually does, because of the increased pace of rainforest destruction.
9,169 square miles of rain forest were cut down in 2003 alone. In Brazil alone, European colonists have destroyed more than 90 indigenous tribes since the 1900's. With them have gone centuries of accumulated knowledge of the medicinal value of rainforest species. As their homelands continue to be destroyed by deforestation, rainforest peoples are also disappearing.
See also
Notes
Template:Mnb Turner, I.M. 2001. The ecology of trees in the tropical rain forest. Cambridge University Press, Cambridge. ISBN 0521801834
Template:Mnb Melillo, J.M., A.D. McGuire, D.W. Kicklighter, B. Moore III, C.J. Vörösmarty and A.L. Schloss. 1993. Global climate change and terrestrial net primary production. Nature 363:234–240.
Template:MnbTian, H., J.M. Melillo, D.W. Kicklighter, A.D. McGuire, J. Helfrich III, B. Moore III and C.J. Vörösmarty. 2000. Climatic and biotic controls on annual carbon storage in Amazonian ecosystems. Global Ecology and Biogeography 9:315–335.
External links
References
- Peters, C.M. et al. "Valuation of an Amazonian Forest", Nature 339: 655-656, 1989.
- The Value of Tropical Forest to Local Communities: Complications, Caveats, and Cautions