The Amazon rainforest, covers much of northwestern Brazil and extends into Colombia, Peru, and
other South American countries.
It is the world’s largest tropical rainforest, famed for its biodiversity.
It’s crisscrossed by thousands of rivers, including the powerful Amazon.
The region is home to about 5 million plants and mammals.
In today's episode, we will look at the contribution of this forest to the human civilization,
natural environment, and biodiversity of the Amazon Rain Forest.
The Amazon rainforest is a moist broadleaf tropical rainforest in the Amazon biome that
covers most of the Amazon basin of South America.
This basin encompasses 7,000,000 km2, of which 5,500,000 km2 area is covered by the rainforest.
This region includes territory belonging to nine nations and 3,344 formally acknowledged
indigenous territories.
The majority of the forest is contained within Brazil, with 60% of the rainforest, followed
by Peru with 13%, Colombia with 10%, and with minor amounts in Bolivia, Ecuador, French
Guiana, Guyana, Suriname, and Venezuela.
The Amazon represents over half of the planet's remaining rainforests, and comprises the largest
and most biodiverse tract of tropical rainforest in the world, with an estimated 390 billion
individual trees divided into 16,000 species.
More than 30 million people of 350 different ethnic groups live in the Amazon, which is
subdivided into 9 different national political systems and 3,344 formally acknowledged indigenous
territories.
Indigenous peoples make up 9% of the total population with 60 of the groups remaining
largely isolated.
Human inhabitants first settled in the Amazon region at least 11,200 years ago.
5 million people may have lived in the Amazon region in AD 1500, divided between dense coastal
settlements, such as that at Marajó, and inland dwellers.
By 1900, the population had fallen to 1 million and by the early 1980s, it was less than 200,000.
The
rainforest likely formed during the Eocene era from 56 million years to 33.9 million
years ago.
It appeared following a global reduction of tropical temperatures when the Atlantic Ocean
had widened sufficiently to provide a warm, moist climate to the Amazon basin.
The rainforest has been in existence for at least 55 million years, and most of the region
remained free of savanna-type biomes at least until the current ice age when the climate
was drier and savanna more widespread.
More than 56% of the dust fertilizing the Amazon rainforest comes from the Bodélé
depression in Northern Chad in the Sahara desert.
The dust contains phosphorus, important for plant growth.
The yearly Sahara dust replaces the equivalent amount of phosphorus washed away yearly in
Amazon soil from rains and floods.
Wet tropical forests are the most species-rich biome, and tropical forests in the Americas
are consistently more species-rich than the wet forests in Africa and Asia.
The region is home to about 2.5 million insect species, tens of thousands of plants, and
some 2,000 birds and mammals.
At least 40,000 plant species, 2,200 fishes, 1,294 birds, 427 mammals, 428 amphibians,
and 378 reptiles have been scientifically classified in the region.
One in five of all bird species are found in the Amazon rainforest, and one in five
of the fish species live in Amazonian rivers and streams.
One square kilometer of the Amazon rainforest can contain about 90,790 tonnes of living
plants.
The average plant biomass is estimated at 355 tonnes per hectare.
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.
The total number of tree species in the region is estimated at 16,000.
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.
The rainforest contains several species that can pose a hazard.
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 is 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.
The Amazon River has an average discharge of approximately 6,591 cubic kilometers per
year, greater than the next seven largest independent rivers combined.
Two of the top ten rivers by discharge are tributaries of the Amazon river.
The Amazon represents 20% of the global riverine discharge into oceans.
The biodiversity in the Amazon is becoming increasingly threatened, primarily by habitat
loss from deforestation as well as the increased frequency of fires.
Over 90% of Amazonian plant and vertebrate species may have been impacted to some degree
by fires.
Deforestation in the Amazon rainforest region has a negative impact on the local climate.
It was one of the main causes of the severe drought in Brazil.
This is because the moisture from the forests is important to the rainfall in Brazil, Paraguay,
and Argentina.
Half of the rainfall in the Amazon area is produced by the forests.
Finally, the Amazon rainforest is called the lung of the planet earth.