It is believed that the name Amazon is said to arise from a war Francisco de Orellana fought with a tribe of Tapuyas and other tribes from South America. The women of the tribe fought alongside the men, as was the custom among the entire tribe. Orellana derived the name Amazonas from the ancient Amazons of Asia and Africa described by Herodotus and Diodorus in Greek legends.
Rainforest must have been formed during the Eocene. It must have formed following a global reduction of tropical temperatures when Atlantic Ocean expanded sufficiently to provide warm and moist climate to the Amazon basin. Since its formation it must have been existed the way it is for about 55 million years mostly free of Savannah type biomes. When the climate became drier the Savannah spread widely.
The extinction of the dinosaurs and the wetter climate may have allowed the tropical rainforest to spread out across the continent. From 65–34 Mya, the rainforest extended as far south as 45°. Climate fluctuations during the last 34 million years have allowed savanna regions to expand into the tropics. During the Oligocene, for example, the rainforest spanned a relatively narrow band that lay mostly above latitude 15°N. It expanded again during the Middle Miocene, then retracted to a mostly inland formation at the last glacial maximum. However, the rainforest still managed to thrive during these glacial periods, allowing for the survival and evolution of a broad diversity of species.
During the mid-Eocene, it is believed that the drainage basin of the Amazon was split along the middle of the continent by the Purus Arch. Water on the eastern side flowed toward the Atlantic, while to the west water flowed toward the Pacific across the Amazonas Basin. As the Andes Mountains rose, however, a large basin was created that enclosed a lake; now known as the Solimões Basin. Within the last 5–10 million years, this accumulating water broke through the Purus Arch, joining the easterly flow toward the Atlantic.
There is evidence that there have been significant changes in Amazon rainforest vegetation over the last 21,000 years through the Last Glacial Maximum (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. There is doubt, 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 and other scientists argue that the rainforest remained largely intact but extended less far to the north, south, and east than is seen today. This has proved difficult to resolve because the practical limitations of working in the rainforest mean that data sampling is biased away from the center of the Amazon basin, and both explanations are reasonably well supported by the available data.
Based on archaeological evidence from an excavation at Caverna da Pedra Pintada, human inhabitants first settled in the Amazon region at least 11,200 years ago. Subsequent development led to late-prehistoric settlements along the periphery of the forest by 1250 AD, which induced alterations in the forest cover. Biologists believe that a population density of 0.2 inhabitants per square kilometre (0.52 /sq mi) is the maximum that can be sustained in the rain forest through hunting. Hence, agriculture is needed to host a larger population.
Some 5 to 7 million people lived in the Amazon region, divided between dense coastal settlements, such as that at Marajó, and inland dwellers. For a long time, it was believed that those inland dwellers were sparsely populated hunter-gatherer tribes. Archeologist Betty J. Meggers was a prominent proponent of this idea, as described in her book Amazonia: Man and Culture in a Counterfeit Paradise. However, recent archeological findings have suggested that the region was actually densely populated.
One of the main pieces of evidence is the existence of the fertile Terra preta (black earth), which is distributed over large areas in the Amazon forest. It is now widely accepted that these soils are a product of indigenous soil management. The development of this soil allowed agriculture and silviculture in the previously hostile environment; meaning that large portions of the Amazon rainforest are probably the result of centuries of human management, rather than naturally occurring as has previously been supposed. In the region of the Xinguanos tribe, remains of some of these large settlements in the middle of the Amazon forest were found in 2003 by Michael Heckenberger and colleagues of the University of Florida. Among those were evidence of roads, bridges and large plazas.
As we all know, Amazon forest is amazingly rich in flora and fauna. Discussing through its wildlife one may find many varieties of native and indigenous species of frogs eg: Giant leaf frog, birds like Scarlet Macaw, and as many as 2.5 million of insect species. It is home for 40 000 plant species, 3000 fish, 1,294 birds, 427 mammals, 428 amphibians, and 378 reptiles. Scientists have described between 96,660 and 128,843 invertebrate species in Brazil alone.
One square kilometer (247 acres) of Amazon rainforest can contain about 90,790 metric tonnes of living plants. The average plant biomass is estimated at 356 ± 47 tonnes ha−1. 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. The green leaf area of plants and trees in the rainforest varies by about 25% as a result of seasonal changes. Leaves expand during the dry season when sunlight is at a maximum, then undergo abscission in the cloudy wet season. These changes provide a balance of carbon between photosynthesis and respiration. Among the largest predatory creatures are the Black Caiman, jaguar, cougar, and anaconda. In the river, electric eels can produce an electric shock that can stun or kill, while piranha are known to bite and injure humans. Various species of poison dart frogs secrete lipophilic alkaloid toxins through their flesh. There are also numerous parasites and disease vectors. Vampire bats dwell in the rainforest and can spread the rabies virus. Malaria, Yellow fever and Dengue fever can also be contracted in the Amazon region.
Farmers near Amazon forest used to cultivate crops by manipulating the forest area. As the nutrient content in the forest soil is surprisingly low (this is because Amazon forest is a highly active eco system and its gross primary productivity is high) farmers keep moving deforesting the area for cultivation. Between 1991 and 2000, the total area of forest lost in the Amazon rose from 415,000 to 587,000 square kilometers (160,000 to 227,000 sq mi), with most of the lost forest becoming pasture for cattle. 70% of formerly forested land in the Amazon, and 91% of land deforested since 1970, is used for livestock pasture. In addition, Brazil is currently the second-largest global producer of soybeans after the United States. The needs of soy farmers have been used to validate many of the controversial transportation projects that are currently developing in the Amazon. The first two highways successfully opened up the rain forest and led to increased settlement and deforestation. The mean annual deforestation rate from 2000 to 2005 (22,392 km2 [8,646 sq mi] per year) was 18% higher than in the previous five years (19,018 km2 [7,343 sq mi] per year). Deforestation has declined significantly in the Brazilian Amazon since 2004.
As a result of deforestation, environmentalists fear the loss in bio diversity as well as the release of the Carbon which could eventually increase global warming. Amazonian evergreen forests account for about 10% of the world's terrestrial primary productivity and 10% of the carbon stores in ecosystems of the order of 1.1 × 1011 metric tonnes of carbon. Amazonian forests are estimated to have accumulated 0.62 ± 0.37 tons of carbon per hectare per year between 1975 and 1996. Some fear that due to emission of green house gases, the forest will be unsustainable and will be lost totally by year 2100 at this rate.
From 2002 to 2006, the conserved land in the Amazon rainforest has almost tripled and deforestation rates have dropped up to 60%. About 1,000,000 square kilometres (250,000,000 acres) have been put onto some sort of conservation, which adds up to a current amount of 1,730,000 square kilometres (430,000,000 acres).
The basin is drained by the Amazon River, the world's largest river in terms of discharge, and the second longest river in the world after the Nile. The river is made up of over 1,100 tributaries, 17 of which are longer than 1000 miles, and two of which (the Negro and the Madeira) are larger, in terms of volume, than the Congo (formerly the Zaire) river. The river system is the lifeline of the forest and its history plays an important part in the development of its rainforests. It spans the borders of eight countries and one overseas territory, is the world's largest river basin and the source of one-fifth of all free-flowing fresh water on Earth. Its rain forests are the planet's largest and most luxuriant, and home to - amazingly - one in ten known species on Earth.
More than 350 indigenous and ethnic groups have lived in the Amazon for thousands of years, tapping nature for agriculture, clothing and traditional medicines. Today, more than 30 million people live in the region. Although most live in large urban centers, all residents remain dependent on the Amazon’s ecosystem services for food, shelter and livelihoods. For the indigenous population the Amazon rainforest is important because it is their home and their culture is closely related to the forest, rivers and fauna. If you destroy the forest you also destroy all the indigenous people that are left. Some of the tribes in the Amazon still have not had contact with outside cultures yet. Can we destroy the indigenous way of life? The people have been happily living for thousands of years. Humanity will lose their language, art, tales, and also their knowledge.
Destruction of the forest had led to many hazardous conditions not only affecting the forest but every inch on the planet. We consider mother earth as one whole unit that constantly working and building and every living species has an ecological niche in its eco system. As the world’s largest rain forest that absorbs most of the CO2 that is released to the atmosphere and a major catchment area as well as a water recycler, Amazon is our responsibility. Protecting it, preserving it and using it sustainably will prosper every living matter on earth including mankind. Its uniqueness that amazes the whole world will be otherwise lost for good. Scientists and botanists and various types of professionals that enter this great green cover discover something new everyday and just imagine that most of the pills and medication we use are from Amazon. It is a reserve of medicinal herbs and truly it is a gift of god. Visit it, admire its beauty and join hands in raising awareness in saving it for the future world.
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