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Amazon Rainforest

2007 Schools Wikipedia Selection. Related subjects: Central & South American
Geography

   River in the Brazilian Amazon Rainforest
   Enlarge
   River in the Brazilian Amazon Rainforest

   The Amazon Rainforest (in Portuguese, Floresta Amazônica or Amazônia —
   and in Spanish, Selva Amazónica) is a moist broadleaf forest in the
   Amazon Basin of South America. The area known as Amazonia or Amazon
   Basin encompasses 7 million km² (1.2 billion acres), though the forest
   itself occupies some 5.5 million km², located within eight nations:
   Brazil (with 60% of the rainforest), Colombia, Peru, Venezuela,
   Ecuador, Bolivia, Guyana and Suriname, as well as French Guiana. States
   or departments in four nations bear the name Amazonas for the Amazon.
   This forest represents over half of the planet's remaining rainforests.
   Amazonian rainforests comprise the largest and most species rich tract
   of tropical rainforest that exists.

Etymology

   The name Amazon arises from a battle which Francisco de Orellana had
   with a tribe of Tapuyas where the women of the tribe fought alongside
   the men, as was the custom among the entire tribe. Orellana derived the
   name Amazonas from the ancient Amazons of Asia and Africa described by
   Herodotus and Diodorus.

Biodiversity

   The Amazon River flowing through the rainforest
   Enlarge
   The Amazon River flowing through the rainforest
   Deforestation in the Amazon Rainforest threatens many species of tree
   frogs, which are very sensitive to environmental changes (pictured:
   Red-eyed Tree Frog)
   Enlarge
   Deforestation in the Amazon Rainforest threatens many species of tree
   frogs, which are very sensitive to environmental changes (pictured:
   Red-eyed Tree Frog)

   Wet tropical forests are the most species-rich biome, and tropical
   forests in the Americas are consistently more species rich than the wet
   forests in Africa and Asia. As the largest tract of tropical rainforest
   in the Americas, the Amazonian rainforests have unparalleled
   biodiversity.

   The region is home to about 2.5 million insect species, tens of
   thousands of plants, and some 2000 birds and mammals. To date, at least
   40,000 plant species, 3,000 fish, 1,294 birds, 427 mammals, 427
   amphibians, and 378 reptiles have been scientifically classified in the
   region . Scientists have described between 96,660 and 128,843
   invertebrate species in Brazil alone .

   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 90,790 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 catalogued .

Deforestation

   Deforestation is the conversion of forested areas to non-forested
   areas. More than one fifth of the Amazon Rainforest has already been
   destroyed , and the forest which remains is threatened. In a span of
   just ten years between 1991 and 2000, the total area of forest lost in
   the Amazon rose from 415,000 to 587,000 km² - an area twice the size of
   Portugal, with most of the lost forest becoming pasture for cattle . In
   1996, the Amazon was reported to have shown a 34% increase in
   deforestation since 1992. The mean annual deforestation rate from 2000
   to 2005 (22,392 km² per year) was 18% higher than in the previous five
   years (19,018 km² per year).

   In Brazil the Instituto Nacional de Pesquisas Espaciais - (National
   Institute of Space Research, or INPE) produces deforestation figures
   annually. Their deforestation estimates are derived from 100 to 220
   images taken during the dry season in the Amazon by the Landsat
   satellite, and only consider the loss of the Amazon rainforest biome –
   not the loss of natural fields or savannah within the rainforest.
   According to INPE, the original Amazon rainforest biome in Brazil of
   4,100,000 km² was reduced to 3,403,000 km² by 2005 – representing a
   loss of 17.1% .

   A new report by a Brazilian congressional committee says the Amazon is
   vanishing at a rate of 52,000 square kilometers per year (20,000 miles²
   per year), over three times the rate for which the last official
   figures were reported in 1994, at this rate the Amazon rainforest will
   be gone by 2050.

Carbon dynamics

   Aerial roots of red mangrove on an Amazonian river
   Enlarge
   Aerial roots of red mangrove on an Amazonian river

   Not only are environmentalists concerned about the loss of biodiversity
   which will result from destruction of the forest, they are also
   concerned about the release of the carbon contained within the
   vegetation, which could accelerate global warming.
   The many plants and scenery of the Amazon Rainforest
   Enlarge
   The many plants and scenery of the Amazon Rainforest

   Amazonian evergreen forests account for about 10% of the world's
   terrestrial primary productivity and 10% of the carbon stores in
   ecosystems — of the order of 1.1 x 10^11 metric tonnes of carbon .
   Amazonian forests are estimated to have accumulated 0.62 ± 0.37 tonnes
   of carbon per hectare per year between 1975 and 1996 . 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.

Conservation

   Some environmentalists commonly state the fact that there is not only a
   biological incentive to protecting the rainforest, but also an economic
   one. One hectare in the Peruvian Amazon has been calculated to have a
   value of $6820 if intact forest is sustainably harvested for fruits,
   latex, and timber; $1000 if clear-cut for commercial timber (not
   sustainably harvested); or $148 if used as cattle pasture. However, the
   assumptions of this study have been widely challenged.

   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, more than 90 indigenous groups have been destroyed by
   colonists since the 1900s, and with them have gone centuries of
   accumulated knowledge of the medicinal value of rainforest species. As
   indigenous territories continue to be destroyed by deforestation, and
   ecocide, such as in the Peruvian Amazon indigenous peoples' rainforest
   communities continue to disappear, while others, like the Urarina
   continue to struggle to fight for their cultural survival and the fate
   of their forested territories. Meanwhile, the relationship between
   nonhuman primates in the subsistence and symbolism of indigenous
   lowland South American peoples has gained increased attention, as has
   ethno-biology and community-based conservation efforts.

Response to climate change

   River in the Amazon rainforest.
   Enlarge
   River in the Amazon rainforest.

   There is evidence that there have been significant changes in Amazon
   rainforest vegetation over the last 21,000 years through the last
   glaciation (LGM) and subsequent deglaciation. Analyses of sediment
   deposits from Amazon basin paleolakes and from the Amazon Fan indicate
   that rainfall in the basin during the LGM was lower than for the
   present, and this was almost certainly associated with reduced moist
   tropical vegetation cover in the basin. There is debate, however, over
   how extensive this reduction was. Some scientists argue that the
   rainforest was reduced to small, isolated refugia separated by open
   forest and grassland; other scientists argue that the rainforest
   remained largely intact but extending less far to the North, South and
   East than is seen today . This debate has proved difficult to resolve
   because the practical limitations of working in the rainforest mean
   that data sampling is biased away from the centre of the Amazon basin,
   and both explanations are reasonably well supported by the available
   data.

   One computer model of future climate change due to greenhouse gas
   emissions shows that the Amazon rainforest could become unsustainable
   under conditions of severely reduced rainfall and increased
   temperatures, leading to an almost complete loss of rainforest cover in
   the basin by 2100. However, simulations of Amazon basin climate change
   across many different models are not consistent in their estimation of
   any rainfall response, ranging from weak increases to strong decreases
   . The result indicates that the rainforest could be threatened though
   the 21st century by climate change in addition to deforestation.

Impact of Amazon drought

   In 2005, parts of the Amazon basin experienced the worst drought in 100
   years, and there are indications that 2006 could be a second successive
   year of drought. A 23 July 2006 article in the UK newspaper The
   Independent reported Woods Hole Research Centre results showing that
   the forest in its present form could survive only three years of
   drought. Scientists at the Brazilian National Institute of Amazonian
   Research argue in the article that this drought response, coupled with
   the effects of deforestation on regional climate, are pushing the
   rainforest towards a " tipping point" where it would irreversibly start
   to die. It concludes that the forest is on the brink of being turned
   into savanna or desert, with catastrophic consequences for the world's
   climate. According to the WWF, the combination of climate change and
   deforestation increases the drying effect of dead trees that fuels
   forests fires.

Video

     * Documentary: About Tristes Tropiques
     * Documentary: War of Pacification in Amazonia

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