The area

The region's rainforest is spread across the Amazon River Basin (approx. 6.7 million km²), a vast natural tropical area more than half of which is located in Brazil. The basin also covers parts of Bolivia, Peru, Colombia, Ecuador, Venezuela and Guyana.

An exceptional biodiversity

A considerable number of the world's plants and animals live in the Amazon, most of which remain undiscovered by scientists. To date, at least 40,000 plant species, 427 mammals, 1,294 birds, 378 reptiles, 427 amphibians, and at least 3,000 fishes¹ have been scientifically classified in the region.

But smaller life forms win hands down in terms of their numbers: just in Brazil, between 96,660 and 128,840 invertebrate species have been described by scientists².

Indigenous cultural richness rivals the Amazon wildlife

Amazon wildlife shares this huge space with some 30 million people³, including more than 220 indigenous groups in the Brazilian Amazon⁴, 40 in Peru and 10 in Ecuador. In Venezuela, some 17 indigenous languages are spoken in the Amazon part of the country. This number is dwarfed by the Bolivian and Colombian Amazon, where 33 and 52 indigenous languages respectively are in use.^*

Behind this incredible cultural diversity lies a stark picture. Despite living in an area with a bewildering array of natural products and services, many local people remain in relative poverty.

The Amazon River, lifeline of the Amazon River Basin

At over 6,400 km, the Amazon River is the world's second longest river, after the Nile in Africa. This massive body of water feeds the basin as it meanders from the high Andes Mountains, all the way to the Atlantic Ocean in the east, discharging almost one-sixth of all freshwater that drains into the world's oceans⁵.

Not just green wilderness

So is the Amazon River Basin merely a huge, uniform expanse of rainforest, bisected by a massive river? Such a perception of the area merely scratches the surface of what is in reality a highly complex and dynamic environment. The basin actually encompasses a variety of landscapes and ecosystems. These include:

• Rainforests
• Floodplain forests
• Savannas
• Rivers

How the Earth's movements created today's Amazon River Basin

Millions of years ago, the Amazon River once flowed from east to west, emptying into the Pacific Ocean. When the Andes Mountains began to rise (due to great pressure on the tectonic plates) along the eastern side of the South American continent about 20 million years ago⁶, this emerging mass blocked the flow of the Amazon River.

Freshwater lakes formed as a result, and the flow of the river gradually reversed to its current eastern course. About 10 million years ago, the river reached the Atlantic Ocean, close to the city of Belem in Brazil.⁷

What it's like to be in the Amazon River Basin

Humid and warm, the region has all the typical attributes of a tropical environment. Temperatures usually average 27.9 °C during the dry season, and 25.8 °C during the rainy season. Relative humidity is quite high at an average of 88% in the rainy season and 77% in the dry season.⁸

The water cycle: a highly efficient natural process

Every year, the Amazon rainforest receives torrential rainfall - between 1,500 mm and 3,000 mm.9 Where does all that water come from?

Eastern trade winds that blow from the Atlantic Ocean account for about half of the rainfall, with the other half due to evapotranspiration - the loss of water from the soil by evaporation and through transpiration from plants¹⁰ - in the Amazon River Basin.¹¹

If evapotranspiration and its role in maintaining ecological balance is disrupted, the climate throughout region - and well beyond - will be significantly impacted.

The unpredictability of an Amazon downpour

In the Amazon River Basin, rainfall follows a seasonal pattern, and there is a great difference in precipitation from one place to the other, even within the centre of the basin.¹²

For example, the city of Iquitos in Peru, along the Amazon River, receives an average of 2,623 mm of rain per year, while Manaus in Brazil, receives 1,771 mm and experiences a strong dry season.¹³

The Amazon between aspirations and reality

As our knowledge of the Amazon constantly increases, so does our understanding of the major ecological services rainforests offer to the local and global community.

While many equate a patch of rainforest with quick rewards - some simply to put food on the table - others see it as a repository of biodiversity, useful chemical compounds or even carbon stocks for the world’s increasing carbon dioxide emissions.

Amazon wildlife, people and rainforests function along with the rhythm of the seasons. However, with the Amazon River Basin under siege from fire and the destructive interventions of humans, this natural system is being reduced to cinder and ash in too many places.

Find out more about the Amazon rainforest, and what WWF is doing to save the Amazon.

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¹Da Silva et al. 2005. The Fate of the Amazonian Areas of Endemism. Conservation Biology 19 (3), 689-694
²Lewinsohn T. M.and Prado P.I. 2005. How Many Species Are There in Brazil? Conservation Biology. Volume 19 (3), 619
³Woodshole Institute. The Amazon. http://www.whrc.org/southamerica/. Accessed 28/9/2005
⁴Instituto Socioambiental. Indigenous peoples in Brazil. http://www.socioambiental.org/pib/english/whwhhow/index.shtm Accessed 7/12/2005
^*Queixalos F, Renault-Lescure O., eds. 2000. The Amazonian languages today. I.R.D., I.S.A., M.P.E.G. Instituto socioambiental, Sao Paolo
⁵WWF. Amazon River and Flooded Forests. http://www.panda.org/about_wwf/where_we_work/ecoregions/
amazon_river_forests.cfm Accessed 7/12/2005
⁶Zeil 1979 in Kricher 1997
⁷Woodshole Institute. The Amazon. http://www.whrc.org/southamerica/. Accessed : 28/9/2005
⁸Junk and Furch, 1985 in Kricher, 1997
⁹Salati and Vose, 1984 in Kricher, 1997
¹⁰US Geological Survey. Glossary. http://biology.usgs.gov/s+t/SNT/noframe/zy198.htm. Accessed 10/10/05.
¹¹Junk and Furch, 1985 and Holloway, 1993 in Kricher, 1997
¹²Junk and Furch, 1985 and Holloway, 1993 in Kricher, 1997
¹³Kircher, 1997

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