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Last updated on April 18, 2014 at 15:11 EDT

Amazon Rainforest

The Amazon Rainforest (known as Floresta Amazônica or Amazônia in Portuguese, and Selva Amazónica or Amazonia in Spanish), also known as Amazonia, or the Amazon Jungle, is a moist broadleaf forest that covers almost all of the Amazon Basin in South America. The basin consists of 1.7 billion acres, of which 1.4 billion acres is rainforest. This rainforest covers nine nations (Brazil, Peru, Colombia, Venezuela, Ecuador, Bolivia, Guyana, Suriname, and French Guiana). Brazil contains nearly 60% of the rainforest, while Peru has nearly 13%. The Amazon Rainforest represents more than half of the planet’s remaining rainforests. It is the largest and most species-rich tropical rainforest on the planet. It has been nominated as one of the New Seven Wonders of the World and is currently listed as number one on group E, which consists of forests, national parks, and nature reserves.

The rainforest most likely formed during the Eocene era, following the evolution of angiosperm plants. These plants appeared after a global reduction of tropical temperatures when the Atlantic Ocean widened enough to provide a warm, moist climate to the Amazon Basin. The rainforest dates back to about 55 million years ago. After the Cretaceous-Tertiary extinction event (when dinosaurs became extinct), wetter climates may have allowed the forest to spread across the continent. From 65 – 34 million years ago the rainforest extended as far south as the Aisen Region of Chile. Climate instability during the last 34 millions years have allowed savanna to expand into tropical areas, stopping the spread of the forests and perhaps shrinking it. It remained relatively calm during the Oligocene era, but expanded again during the Middle Miocene era. It retracted to mostly how it looks today during the Last Glacial Maximum (about 20,000 years ago).

During the mid-Eocene era, it is theorized that the drainage basin of the Amazon split into two tracts along the middle of the continent by the Purus Arch (a continental rise that caused water to run east and west toward the oceans). As the Andes Mountains rose, a large basin was created that created a lake, now known as the Solimões Basin. The waters rose in this basin over the last 5 to 10 million years, causing the water to overflow and break through the Purus Arch and rejoining the easterly flow toward the Atlantic.

Evidence shows that there has been significant changes in the rainforest vegetation over the last 21,000 years through the Last Glacial Maximum (LGM) and the subsequent glacial melting. Studies of sediment deposits from the Amazon Basin and surrounding areas, indicate that rainfall was lower during the LGM than it currently is today. This is quite clearly associated with the reduced tropical vegetation cover in the basin. There is much debate over how extensive this reduction was.

Based on archaeological evidence, human inhabitants first settled in the Amazon region at least 11,200 years ago. Subsequent evidence has shown that late-prehistoric settlements were established along the borders of the forest 3300 years ago. It is estimated that only about 1 person per 3 square miles could be sustained in the rainforest through hunting, hence, agriculture is needed to sustain larger populations. The first European to travel the length of the Amazon River was Francisco de Orellana in 1542.

Wet tropical forests are the most species-rich biome (complex community of living organisms such as plants and animals), and the tropical forests of the Americas are constantly more species rich than any other rainforest on the planet. The Amazon Rainforest has unmatched biodiversity. One in ten known species in the world are found in the Amazon. The Amazon Rainforest has the largest collection of living plants and animals in the world. About 2.5 million insect species, 40,000 plant species, 3,000 fish species, 1294 bird species, 427 mammal species, 428 amphibians, and 378 reptiles have been scientifically classified in this rainforest region. One in five of all the birds in the world live in the Amazon Rainforest, and over 125,000 invertebrate species have been recorded in Brazil alone. The diversity of plant species is the highest on the planet and some reports have been made of up to 75,000 types of trees and more than 150,000 species of plants in all may be found in just one square mile of rainforest. This same square mile may contain more than 90,000 tons of living plants.

There are several potentially harmful species that are found in the Amazon Rainforest. The largest predators are the Black Caiman, Jaguar, and Anaconda. In the river, electric eels and Piranha can be deadly. Poison Dart Frogs secrete toxins that can be fatal. There are numerous parasites and bacteria/disease transmitters too. Vampire bats can spread the rabies virus. Malaria, yellow fever, and Dengue fever all can be contracted in the Amazon region.

Deforestation has occurred in the rainforest since the early 1960s. Prior to 1960, access to the interior of the forest was highly restricted, and the forest remained mostly intact. Human settlements including farms were the first establishments that utilized the slash and burn technique of removing forests to create cultivated lands. Due to weed invasion and the loss of soil fertility, the farmers could not manage their fields and had to keep moving their farms and clearing new areas. These farming methods have led to deforestation on a wide scale and have caused extensive environmental damage. Between 1991 and 2000, the total area of forest lost in the Amazon grew from 260,000 to 365,000 sq miles. Almost all of the lost forests became pasture for cattle. The average annual rate of deforestation from 2000 to 2005 was 14,000 sq miles, which was an 18% increase than in the previous five years (12,000 sq miles). If the current trends continue, the Amazon Rainforest will be reduced by 40% in just 25 years, and in 100 years, it could completely disappear.

Between deforestation and the release of carbon contained within vegetation, which could accelerate global warming, environmentalists are concerned that there could be a great loss of biodiversity in the rainforests within the next century. A computer model of future climate change caused by greenhouse gases shows that the Amazon could become unsustainable by the year 2100, due to reduced rainfall, increasing temperatures, deforestation and carbon emissions. As rainforests continue to be destroyed, so do indigenous communities.

Conservation of the rainforest became increasingly significant with the relationship discovered between some lowland South American communities and their primate counterparts. Since 2002, conserved land in the Amazon Rainforest has nearly tripled and deforestation rates have dropped up to 60% in localized areas. Nearly 250,000,000 acres of rainforest have been added to the conservation list since 2002, which now stands at about 430 million acres.

Remote sensing is a program that is now drastically improving conservationists’ knowledge of the Amazon Basin. This technology helps assess the extent of damage from deforestation through satellite-based analysis. Remote sensing may be the best and possibly the only way to study the Amazon on a large scale. Indigenous communities are also using remotely sensed data to help protect their lands from commercial interests. Using handheld GPS devices and programs such as Google Earth, members of one tribe who live in the rainforests of southern Suriname, map out their territories to help strengthen their claims. Most Amazon tribes, however, do not have clearly marked and defined boundaries, which make their territories easy targets for commercial interests.

One of the worst droughts to strike the Amazon Rainforest in 100 years, occurred in 2005 and almost continued into 2006. Currently it is estimated that the rainforest could not handle more than three consecutive years of drought. Between severe drought, and continued deforestation, the rainforest is being pushed toward a “tipping point” where it would begin to die. If the rainforest dies and/or turns to savanna or desert, it will cause catastrophic consequences on the world’s climate. The combination of climate change and deforestation increases the drying effect of dead trees and in turn fuels massive forest fires that could also speed up the death and destruction of the Amazon.

The rainforest has been politically bombarded as well. Some politicians believe that the Amazon belongs to all of humanity, not just the people of South America. The Brazilian press, government and society suggest that this controversy hurts the nation’s sovereignty. The New York Times posted an article in May 2008 titled “Whose Rain Forest Is This, Anyway?” The article struck a chord with Brazilian President Lula, whom responded that “the Amazon belongs to Brazilians!”. The Brazilian society has debated if the Amazon could be invaded resulting in a war. The Brazilian Amazon border is patrolled and heavily guarded by the Brazilian Army.

Image Credit: Wikipedia (public domain)

Amazon Rainforest