(river) South American river, the world's second longest, 6,570 km/4,080 mi, and the largest in volume of water. Its main headstreams, the Marańón and the Ucayali, rise in central Peru and unite to flow E across Brazil for about 4,000 km/2,500 mi. It has 48,280 km/30,000 mi of navigable waterways, draining 7,000,000 sq km/2,750,000 sq mi, nearly half the South American landmass. It reaches the Atlantic on the equator, its estuary 80 km/50 mi wide, discharging a volume of water so immense that 64 km/40 mi out to sea, fresh water remains at the surface. The Amazon basin covers 7.5 million sq km/3 million sq mi, of which 5 million sq km/2 million sq mi is tropical forest containing 30% of all known plant and animal species (80,000 known species of trees, 3,000 known species of land vertebrates, 2,000 freshwater fish). It is the wettest region on Earth; average rainfall 2.54 m/8.3 ft a year.
The opening up of the Amazon river basin to settlers from the overpopulated east coast has resulted in a massive burning of tropical forest to create both arable and pasture land. The problems of soil erosion, the disappearance of potentially useful plant and animal species, and the possible impact of large-scale forest clearance on global warming of the atmosphere have become environmental issues of international concern.
Brazil, with one third of the world's remaining tropical rainforest, has 55,000 species of flowering plant, half of which are only found in Brazilian Amazonia. In June 1990 the Brazilian Satellite Research Institute announced that 8% of the rainforest in the area had been destroyed by deforestation, amounting to 404,000 sq km/155,944 sq mi (nearly the size of Sweden). + prikaži više