Rain Forest

All Rain Forest in the world

06.10.2007.

Amazon Rainforest

The Amazon Rainforest (Brazilian Portuguese: Floresta Amazônica or Amazônia; Spanish: Selva Amazónica or Amazonía) is a moist broadleaf forest in the Amazon Basin of South America. The area, also known as Amazonia or the Amazon Basin, encompasses seven million square kilometers (1.2 billion acres), though the forest itself occupies some 5.5 million square kilometers, located within nine nations: Brazil (with 60 percent of the rainforest), Colombia, Peru, Venezuela, Ecuador, Bolivia, Guyana, Suriname, and French Guiana. States or departments in four nations bear the name Amazonas after it. The Amazon represents over half of the planet's remaining rainforests and comprises the largest and most species-rich tract of tropical rainforest in the world.


Etymology

The name Amazon is said to arise 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. Another theory credits the name to Orellana mistaking indigenous men wearing "grass skirts" as women. Orellana derived the name Amazonas from the ancient Amazons of Asia and Africa described by Herodotus and Diodorus in Greek legends.

Biodiversity

The Amazon River flowing through the rainforest
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: Giant leaf frog)
Deforestation in the Amazon Rainforest threatens many species of tree frogs, which are very sensitive to environmental changes (pictured: Giant leaf 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.[1] As the largest tract of tropical rainforest in the Americas, the Amazonian rainforests have unparalleled biodiversity. More than 1/3 of all species in the world live in the Amazon Rainforest.[2]

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 [3]. Scientists have described between 96,660 and 128,843 invertebrate species in Brazil alone.[4]

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 tonnes of living plants.[5][6] 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. The main sources of deforestation in the Amazon are human settlement and development of the land.[7] 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.[8]

History of Deforestation in the Amazon

Urarina shaman, 1988.
Urarina shaman, 1988.

Prior to the early 1960’s, access to the Amazon was incredibly restricted and aside from partial clearing along rivers the forest remained basically intact.[9] The key point in deforestation of the Amazon was when the colonists established farms within the forest during the 1600s. Their farming system was based on crop cultivation and the slash and burn method. The colonists were unable to successfully manage their fields and the crops due to the loss of soil fertility[10]. The soils in the Amazon are productive for just a short period of time, and the farmers are therefore constantly moving and clearing more and more land[11]. Amazonian colonization was ruled by cattle raising because ranching required little labor, generated decent profits, and awarded social status in the community. However the results of the farming lead to extensive deforestation and caused extensive environmental damage[12]. An estimated 30% of the deforestation is due to small farmers and the intensity within the area that they inhabit is greater than the area occupied by the medium and large ranchers who possess 89% of the Legal Amazon’s private land. This emphasizes the importance of using previously cleared land for agricultural use, rather the typical easiest political path of distributing still-forested areas[13]. In the Brazilian Amazon, the amount of small farmers versus large landholders changes frequently with economic and demographic pressures.[14]
and weed invasion

Causes of Deforestation in the Amazon

The annual rate of deforestation in the Amazon region has continued to increase from 1990 to 2003 because of factors at local, national, and international levels.[15] 70% of formerly forested land in the Amazon, and 91% of land deforested since 1970, is used for livestock pasture.[16][17] In addition, Brazil is currently the second-largest global producer of soybeans[18] Cleared property is also valued 5–10 times more than forested land and for that reason valuable to the owner whose ultimate objective is resale. As stated by Michael Williams,“The people of Brazil have always thought of the Amazon as a communal possession which they felt free to hack, burn, and abandon at will.”[19] The soy industry is the principal source of foreign currency for Brazil; therefore, the needs of soy farmers have been used to validate many of the controversial transportation projects that are currently developing in the Amazon.[20] The first two highways: the Belém-Brasília (1958) and the Cuiaba-Porto Velho (1968) were the only federal highways in the Legal Amazon to be paved and passable year-round before the late 1990’s. These two highways are said to be “at the heart of the ‘arc of deforestation’,” which at present is the focal point area of deforestation in the Brazilian Amazon. The Belém-Brasilia highway attracted nearly two million settlers in the first twenty years. The success of the Belém-Brasilia highway in opening up the forest was re-enacted as paved roads continued to be developed unleashing the irrepressible spread of settlement. The completions of the roads were followed by a wave of resettlement and the settlers had a significant effect on the forest.[21]
after the United States, mostly for livestock feed, and as prices for soybeans rise, the soy farmers are pushing northwards into forested areas of the Amazon. As stated in Brazilian legislation, clearing land for crops or fields is considered an ‘effective use’ of land and is the beginning towards land ownership.

Scientists using NASA satellite data have found that clearing for mechanized cropland has recently become a significant force in Brazilian Amazon deforestation. This change in land use may alter the region's climate and the land's ability to absorb carbon dioxide. Researchers found that in 2003, the peak year of deforestation, more than 20 percent of the Mato Grossocroplandsoybean prices fell by more than 25 percent and some areas of Mato Grosso showed a decrease in large deforestation events, although the central agricultural zone continued to clear forests. But, deforestation rates could return to the high levels seen in 2003 as soybean and other crop prices begin to rebound in international xafss. Brazil has become a leading worldwide producer of grains including soybean, accounting for more than one-third of the country's gross national product. This new driver of forest loss suggests that the rise and fall of prices for other crops, beef and timber may also have a significant impact on future land use in the region, according to the study.[1] state’s forests were converted to cropland. This finding suggests that the recent expansion in the region is contributing to further deforestation. In 2005,

Measured Rates of Deforestation in the Amazon

In 1996, the Amazon was reported to have shown a 34% increase in deforestation since 1992[22]. 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) [23]. In Brazil, the Instituto Nacional de Pesquisas Espaciais (INPE, or National Institute of Space Research) 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, also may 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% [24].

Period Estimated Remaining Forest Cover
in the Brazilian Amazon (sq. km)
Annual forest
loss (sq. km)
Percent of 1970
cover remaining
Total forest loss
since 1970 (sq. km)
pre-1970 4,100,000    
1977 3,955,870 21,130 96.50% 144,130
1978-1987 3,744,570 21,130 91.30% 355,430
1988 3,723,520 21,050 90.80% 376,480
1989 3,705,750 17,770 90.40% 394,250
1990 3,692,020 13,730 90.00% 407,980
1991 3,680,990 11,030 89.80% 419,010
1992 3,667,204 13,786 89.40% 432,796
1993 3,652,308 14,896 89.10% 447,692
1994 3,637,412 14,896 88.70% 462,588
1995 3,608,353 29,059 88.00% 491,647
1996 3,590,192 18,161 87.60% 509,808
1997 3,576,965 13,227 87.20% 523,035
1998 3,559,582 17,383 86.80% 540,418
1999 3,542,323 17,259 86.40% 557,677
2000 3,524,097 18,226 86.00% 575,903
2001 3,505,932 18,165 85.50% 594,068
2002 3,484,727 21,205 85.00% 615,273
2003 3,459,576 25,151 84.40% 640,424
2004 3,432,147 27,429 83.70% 667,853
2005 3,413,354 18,793 83.30% 686,646
2006 3,400,254 13,100 82.90% 699,746

Future of Deforestation

At the current rate, in two decades the Amazon Rainforest will be reduced by 40%. [26] The 2005-2006 year had a 41% drop in deforestation, this was the lowest figure since 1991. Deforestation rates are expected to go down as conservation has been at a very high rate in the past five years. At this rate, it is possible that the Amazon Rainforest will no longer exist by the end of the century.

Links to Main Causes for deforestation

  • Slash and burn agriculture
  • Construction of the Transamazonian Highway
  • Logging

Carbon dynamics

Aerial roots of red mangrove on an Amazonian river
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.

Amazonian evergreen forests account for about 10% of the world's terrestrial primary productivity and 10% of the carbon stores in ecosystems [27] — of the order of 1.1 x 1011 metric tonnes of carbon [28]. Amazonian forests are estimated to have accumulated 0.62 ± 0.37 tonnes of carbon per hectare per year between 1975 and 1996 [28]. 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 come from logging and burning in the Amazon. Despite this, Brazil is listed as one of the lowest per capita (rank 124) in CO2 emissions according to the US Department of Energy's Carbon Dioxide Information Analysis Center (CDIAC) (see List of countries by carbon dioxide emissions per capita).

Conservation

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

Environmentalists have stated 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.[29]

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, and the increase in the greenhouse gases emission by industrialized countries. 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 epidemics and Brazilian 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[30] 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.

From 2002 to 2006, the conserved land in the Amazon Rainforest has almost tripled and deforestation rates have dropped up to 60%. About 100 million hectares, or 250 million acres have been put onto some sort of conservation, which adds up to a current amount of 173 million hectares or 432.5 million acres. [31]

Response to climate change

Anthropogenic emission of greenhouse gases broken down by sector for the year 2000.
Anthropogenic emission of greenhouse gases broken down by sector for the year 2000.

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[32]. 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[33]; other scientists argue that the rainforest remained largely intact but extending less far to the North, South and East than is seen today [34]. 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.[35][36] 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 [37]. 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[38], and there are indications that 2006 could be a second successive year of drought[39]. A 23 July 2006 article in the UK newspaper The Independent reported Woods Hole Research Center results showing that the forest in its present form could survive only three years of drought.[40][41]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. Scientists at the Brazilian

According to the WWF, the combination of climate change and deforestation increases the drying effect of dead trees that fuels forest fires.


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