Basic Information

In order to get newcomers started right, I have gathered some backround information here. This should be enough backup for discussions, though if anyone has something to add to that, he or she can comment. So here we go!

The Amazon Rainforest – A short Intro
The Amazon Rainforest is the largest tropical rainforest on earth. It has seasonal forests, rainforests, deciduous & flooded forests and savannas, all drained by the Amazon River. The whole Amazon covers around 40% of South America, with estimated 8,235,430 square km (3,179,715 square mi). This is almost as big as the USA including Alaska and Hawaii. 60% of the main Amazon concentrate in Brazil, the rest lies in Peru, Columbia, Venezuela, Ecuador, Bolivia, Guyana, Suriname and French Guiana. Some of its arms even reach far north all through Middle America up to Mexico, or south to Argentina and Paraguay.

The Amazon River
The Amazon River is the world’s largest and 2nd longest river. Over 1100 tributaries, of which 17 are longer than 1000 mi themselves, drain as much land as the USA. The mouth ends in a ca. 483 km (300 mi) wide delta. During the high water season, up to 183 million cubic meters (600 billion cubic ft) of water can flow into the Atlantic Ocean, which only mix with the salt water after 200 km (125 mi). Early sailors could drink from the ocean before even sighting South America. Each day, 32.3 million cubic meters (106 million cubic ft) of suspended sediment are swept into the ocean. The result of that is the Marajo Island, a river island the size of Switzerland.

The Four layers
The Amazon Rainforest consists of four main layers: the forest floor, the undergrowth, the canopy and the emergent layer.
The forest floor is the lowest and darkest part of the rainforest. Only around 2% of the natural sunlight reach the forest floor. The top 5 cm (2 inch) of soil contain ca. 99% of the soils nutrients. That is why most roots of the massive trees and plants are quite shallow.
The undergrowth barely receives light either. 2-5 % of the light filter through, and the plants have adapted to the darkness with giant dark green leaves. Due to the sparse wind, plants depend on insects and other animals for the spread of their seeds.















In the canopy most of the life takes place. It is the densest part of the forest and around 80% of the light are filtered here, darkening everything lower. Most of the flowers and fruits flourish here. Epiphytes cover every possible space, and bromeliads offer an important water source.
The highest places in the rainforest are the trees of the emergent layer. They can be 60 m (200 ft) tall and their trunks can have 4 m (16 ft) circumference. Many species living in the emergent layer never touch the ground because everything they need they find there.

Fauna of the Amazon
It is estimated that about 30% of all species on earth inhabit the Amazon. There are more than 360 mammal species, ca. 1400 bird species, 430 amphibians, 380 reptile kinds, more than 3000 freshwater fish and 2.5 million insect kinds. One square mile (2.6 square km) can often house more than 50,000 insect species and a single bush most likely contains more ant kinds than the British Isles. Some scientists estimate that around 30% of the Amazon’s total biomass are made up of ants. Over 90% of the animal species in the Amazon Basin are insects.

The majority of mammals are bats and rodents, and the Amazon is home to the world’s largest rodent, the capybara, which can weigh 91 kg (200 lbs). Yet, there also are the edentates (e.g. sloths, armadillos, anteaters…) which only exist in America, or the two river dolphins the Boto and the Tucuxi (the Tucuxi are not considered true river dolphins because they also live in the ocean). By the way, many traditional saltwater creatures, like for example the dolphins, or sponges and stingrays, have adapted to the Amazon River and its network of tributaries.

There are more than 1000 frog kinds in the Amazon Basin, of which the majority live in the canopy of the trees. The major difference between temperate frogs and those in the rainforest is that temperate frogs are limited to bodies of water because their skin needs to stay moist for their respiration. Tropical frogs live in a very moist environment which enables them to leave water and so escape many predators like fish, shrimps, aquatic insects and their larvae. This also explains the high prosperity of tropical frogs in contrast to temperate ones. Probably, amongst the most known frog kinds of the Amazon is the brilliantly colored poison dart frog. Even though they are quite slow moving, these frogs secrete powerful toxins. Their remarkable color is there to warn potential predators.

Many fish of the Amazon are important dispersers of tree seeds. Often they migrate hundreds of kilometers up and down the river, like the Piramutaba catfish, which is thought to migrate around 3300 km (2050 mi) up to its spawning grounds in the upper Amazon. The largest freshwater fish of the world is the Pirarucu (i.e. Arapaima). It is found in the waters of Peru, Ecuador, Brazil, Columbia and Bolivia and can reach up to 5 m (16 ft) length and weigh 600 kg.

Smuggling living animals, especially exotic ones like those from the Amazon, is forth after drugs, diamonds and weapons in the smuggling business. This is a great problem, especially concerning reptiles and birds of the Amazon Rainforest. The rarest bird on earth, the Spix's macaw, was limited to four birds still remaining in the wild in 1987. It always had been quite rare, due to the limited possible ecosystems (palm groves and river edges in the center of Brazil) but deforestation, imported African bees and especially over-collection by bird fans have lead to its great decrease. Now, it is believed to be totally extinct in the wild, and there are around 120 birds remaining in captivity. 78 of them are bred for an international reestablishment program, and the fight for survival goes on.

Amazonian Flora
There are around 438,000 plant species described up to date, yet there are many more. 1 ha alone can often house more than 480 different species of trees.
A very remarkable thing about the plants in Amazonia is their adaption to the different levels of the forest (i.e. the forest floor or the canopy). Plants in the undergrowth for example have large green leaves to catch the little light left. In the canopy a lot of plants have so called ‘drop tip’ leaves, large smooth oval leaves ending in a tip. This way rainwater runs down the leaves and does not gather and mosses, fungi and lichens cannot form. And trees in the emergent layer have rough small leaves with a waxy substance to hold water. They also use the wind by growing winged seeds which are carried to other regions of the Amazon.

Indigenous People
500 years ago, around 10 million native people inhabited the Amazon and its surroundings. Now there are less than 200,000 left, either westernized or deep inside the woods.
Many natives, especially shamans and medicine men, possess very important knowledge about the plants and their properties. This knowledge is already being used in the medical and cosmetic business, but often these people are exploited and then left aside, and the great knowledge slowly dies away with its people – Since the 20th century more than 90 tribes have been destroyed by globalization and forget their old traditions alongside with the old wisdom. On the other hand you cannot forbid them to go to school, have a television or an air-condition. The natives of the Amazon are caught up between modern and of course more comfortable living and the old traditional ways.

Destruction
20% of the Amazon are gone now. Land is being cleared for cattle, for agriculture, mining and logging. Forests are being burned for charcoal. It is estimated that in less than 40 years the Amazon and all the other rainforests around the globe will be entirely vanished from the earth’s surface if deforestation goes on at such a pace. Every day around 80,000 acres of rainforest, which is equal to 800 km2 (308.88 mi2) on earth are lost to the fire and the saw, and 130 species of plants and animals. And that even though the Amazon Rainforest alone creates 20% of the world’s oxygen and captures thousands of tons of carbon dioxide. It truly is the earth’s green lung and we are destroying it.

sources (all information extracted 2008):
main source: http://rainforests.mongabay.com/amazon/
other sources:
http://amazon-river.swicki.com/ (for the four layers of the rainforest)
http://en.wikipedia.org/wiki/ (for the description of different animals; eventhough wikipedia is not considered a reliable source, I do think, for certain infos, it is legitimate to use it)