The forest lies in a basin drained largely by the Amazon River, with 1,100 tributaries. This basin was formed in the Palaeozoic period, between 500 and 200 million years ago. The diversity of plant species is the highest on earth with some experts estimating that one hectare (2.47 acres) may contain over 750 types of trees and 1500 species of higher plants. One hectare of Amazon rainforest can contain about 900 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.)
There has been concern among environmentalists for many years, regarding the deforestation of the region, stemming mainly from the fact that more than one fifth of the Amazon Rainforest has already been destroyed; and much more is severely threatened as destruction continues to escalate. The deforestation of this area in the 1980s was largely considered catastrophic. Yet, 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 20,000 square miles a year, over three times the rate for which the last official figures were reported, in 1994.
"If nothing is done, the entire Amazon will be gone within 50 years," - Rep. Gilney Vianna of the leftist Worker's Party in the Amazon state of Mato Grosso.
Environmentalists commonly stress 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 provide potential earnings of $6,820 per year if intact forest is sustainably harvested for fruits, latex, and timber; $1,000 if clear-cut for commercial timber (not sustainably harvested); or $148 if used as cattle pasture.