The Amazon basin is the part of South America drained by the Amazon River and its tributary. The Amazon drainage basin covers an area of about ,[Goulding, M., Barthem, R. B. and Duenas, R. (2003). The Smithsonian Atlas of the Amazon, Smithsonian Books ]
Most of the basin is covered by the Amazon rainforest, also known as Amazonia. With a
Geography
The Amazon River begins in the
Andes at the west of the basin with its main tributary the Marañón River and Apurimac River in
Peru. The highest point in the
Drainage divide of the Amazon is the second biggest peak of Yerupajá at .
The Amazon River Basin occupies the entire central and eastern area of South America, lying to the east of the Andes mountain range and extending from the Guyana Plateau in the north to the Brazilian Plateau in the south.
With a length of about before it drains into the Atlantic Ocean, it is one of the two longest rivers in the world. A team of scientists has claimed that the Amazon is longer than the Nile,
The Amazon system transports the largest volume of water of any river system, accounting for about 20% of the total water carried to the oceans by rivers. Some of the Amazon rainforests are deforested because of an increase in cattle ranches and soybean fields. The Amazon basin formerly flowed west to the Pacific Ocean until the Andes formed, causing the basin to flow eastward towards the Atlantic Ocean.
Politically the basin is divided into Peruvian Amazonia, Amazônia Legal of Brazil, the Amazon natural region of Colombia, Amazonas (Venezuelan state), and parts of Bolivia and Ecuador.
+Distribution of the Amazon River basin area and discharge between countries |
| Bolivia | | 724,000 | 10.4 | 291 | 4.0 |
| Brazil | 4,674,619 | 67.5 | 4,167.3 | 57.2 |
| | Acre | 164,123 | 3.5 | 144.2 | 2.0 |
| Amapá | 44,870 | 1.0 | 57.7 | 0.8 |
| Amazonas | 1,559,159 | 33.3 | 1,848.3 | 25.4 |
| Brasília | 1,010 | 0.02 | | |
| Goiás | 212,131 | 4.5 | 96.7 | 1.3 |
| Maranhão | 39,396 | 0.8 | 9.4 | 0.1 |
| Mato Grosso | 723,470 | 15.5 | 490.6 | 6.7 |
| Pará | 1,190,147 | 25.5 | 1,053.1 | 14.5 |
| Rondônia | 237,591 | 5.08 | 140.6 | 1.9 |
| Roraima | 224,301 | 4.8 | 211.6 | 2.9 |
| Tocantins | 278,421 | 6.0 | 115.1 | 1.6 |
| Ecuador | | 146,688 | 2.1 | 258.4 | 3.6 |
| Guyana | 12,224 | 0.2 | 8.8 | 0.1 |
| Colombia | 345,293 | 5.0 | 755 | 10.4 |
| Peru | 967,176 | 14.0 | 1,739.5 | 23.9 |
| Venezuela | 53,000 | 0.8 | 60.0 | 0.8 |
| |
| Amazon basin | 6,923,000 | 100.0 | 7,280 | 100.0 |
Plant life
Plant growth is quite dense and its variety of animal inhabitants is comparatively high due to the heavy rainfall and the dense and extensive evergreen and coniferous forests. Little
sunlight reaches the ground due to the dense roof of canopy by plants. The ground remains dark and damp and only shade-tolerant vegetation will grow here.
and
exploit trees and other plants to get closer to the sunlight. They grow hanging onto the branches or tree trunks with
aerial roots, not as parasites but as
. Species of tropical trees native to the Amazon include
Brazil nut,
rubber tree and
Assai palm.
Wildlife
Mammals
More than 1,400 species of
are found in the Amazon, the majority of which are species of
and
. Its larger mammals include the
jaguar,
ocelot,
capybara,
Cougar and South American tapir.
Birds
About 1,500
bird species inhabit the Amazon basin.
The
biodiversity of the Amazon and the sheer number of diverse bird species is given by the number of different bird families that reside in these humid forests. An example of such would be the
cotinga family, to which the Guianan cock-of-the-rock belong. Birds such as
, and
are also found here.
are famous for duck gathering by the hundreds along the clay cliffs of the Amazon River. In the western Amazon hundreds of
and other
descend to exposed river banks to consume clay on an almost daily basis,
[Munn, C. A. 1994. Macaws: winged rainbows. National Geographic, 185, 118–140.] the exception being rainy days.
Reptiles
The
green anaconda inhabits the shallow waters of the Amazon and the emerald tree boa and
boa constrictor live in the Amazonian tree tops.
Many reptile species are illegally collected and exported for the international pet trade. Live animals are the fourth largest commodity in the smuggling industry after drugs, diamonds and weapons.
Amphibians
More than 1,500 species of
swim and are found in the Amazon. Unlike temperate
which are mostly limited to
near the water, tropical frogs are most abundant in the trees and relatively few are found near bodies of water on the
forest floor. The reason for this occurrence is quite simple: frogs must always keep their
skin moist since almost half of their respiration is carried out through their skin. The high
humidity of the rainforest and frequent
gives tropical frogs infinitely more freedom to move into the trees and escape the many
of rainforest waters. The differences between temperate and tropical frogs extend beyond their habitat.
Fish
About 2,500
fish species are known from the Amazon basin and it is estimated that more than 1,000 additional undescribed species exist.
This is more than any other river basin on Earth, and Amazonia is the center of diversity for
.
About 45% (more than 1,000 species) of the known Amazonian fish species are
Endemism to the basin.
The remarkable species richness can in part be explained by the large differences between the various parts of the Amazon basin, resulting in many fish species that are endemic to small regions. For example, fauna in clearwater rivers differs from fauna in white and
, fauna in slow moving sections show distinct differences compared to that in
rapids, fauna in small streams differ from that in major rivers, and fauna in shallow sections show distinct differences compared to that in deep parts.
[Mendonça, F. P., W. E. Magnusson, J. Zuanon and C. M. Taylor. (2005) Relationships between habitat characteristics and fish assemblages in small streams of Central Amazonia. Copeia 2005(4): 751–764][Duncan, W.P.; and Fernandes, M.N. (2010). Physicochemical characterization of the white, black, and clearwater rivers of the Amazon Basin and its implications on the distribution of freshwater stingrays (Chondrichthyes, Potamotrygonidae). PanamJAS 5(3): 454–464.] By far the most diverse orders in the Amazon are
Characiformes (43% of total fish species in the Amazon) and
Siluriformes (39%), but other groups with many species include
Cichlidae (6%) and
Gymnotiformes (3%).
In addition to major differences in behavior and ecology, Amazonian fish vary extensively in form and size. The largest, the arapaima and piraiba can reach or more in length and up to in weight, making them some of the largest strict freshwater fish in the world.
The Amazon supports very large fisheries, including well-known species of large catfish (such as Brachyplatystoma, which perform long breeding Fish migration up the Amazon), arapaima and tambaqui, and is also home to many species that are important in the aquarium trade, such as the oscar, discus, Pterophyllum, Corydoras and neon tetra.
Several cavefish species in the genus Phreatobius are found in the Amazon, as is the cave-dwelling Astroblepus pholeter in the far western part of the basin (Andean region).
Some of the major fish groups of the Amazon basin include:
Insects
More than 90% of the animal species in the Amazon are
,
of which about 40% are
(Coleoptera constituting almost 25% of all known types of animal life-forms.)
[Powell (2009)]
Whereas all of Europe has some 321 butterfly species, the Manú National Park in Peru (4,000 hectare-survey) has 2,300 species, while Tambopata National Reserve (5,500 hectare-survey) has at least 1,231 species.
Climate
The
Amazon River basin has a low-water season (known popularly as summer), and a wet season (known popularly as winter) during which, the rivers
flood the adjacent, low-lying forests. The
climate of the basin is generally hot and humid. In some areas, however, the summer months (June–September) can bring cold snaps, fueled by Antarctic winds traveling along the adjacent mountain range. The average annual temperature is around 25-degree and 28
degree Celsius with little to no distinction between summer and winter season.
Human lifestyle
Amazonia i
Population density|sparsely populated]]. There are scattered settlements inland, but most of the population lives in a few larger cities on the banks of the Amazon and other major rivers, such as in
Iquitos – Loreto in
Peru,
Manaus-Amazonas State, and Belém, Pará. In many regions, the forest has been cleared for
soya bean and
ranching (the most extensive non-forest use of the land); some of the inhabitants harvest wild
rubber latex, and
Brazil nut. This is a form of extractive farms, where the trees are not cut down. These are relatively sustainable operations in contrast to lumbering or agriculture dependent on clearing the rainforest. The people live in thatched houses shaped liked beehives. They also build apartment-like houses called "
Maloca", with a steeply slanting roof.
Languages
The most widely spoken languages in the Amazon are Portuguese and
Spanish language. There are hundreds of
First language still spoken in the Amazon, most of which are critically endangered.
Indigenous peoples
Many tribal groups live in the Amazon Basin, often in relative isolation. It is estimated 400 or more tribal groups have lived in the Amazon Basin for hundreds of years with their own culture, language, and lifestyle. Today total population of Amazon basin is 1.5 million distributed. There are an estimated 100 uncontacted tribal groups.
The largest organization fighting for the indigenous peoples in this area is COICA. It is a supra organization encompassing all indigenous rights organizations working in the Amazon basin area, and covers the people living in several countries.
River commerce
The river is the principal path of transportation for people and produce in the regions, with transport ranging from balsa
and
to hand built wooden river craft and
watercraft hulled craft.
Agriculture
Seasonal floods excavate and redistribute nutrient-rich silt onto beaches and islands, enabling dry-season riverside agriculture of rice, beans, and corn on the river's shoreline without the addition of fertilizer, with additional slash and burn agriculture on higher floodplains. Fishing provides additional food year-round, and
Pastured poultry need little or no food beyond what they can forage locally.
Charcoal made largely from forest and shoreline deadfall is produced for use in urban areas. Exploitation of
bushmeat, particularly
deer and
is common.
Extensive deforestation, particularly in Brazil, is leading to the extinction of known and unknown species, reducing Biodiversity and adversely impacting soil, water, and air quality. A final part of the deforestation process is the large-scale production of charcoal for industrial processes such as steel manufacturing. Soils within the region are generally shallow and cannot be used for more than a few seasons without the addition of imported fertilizers and chemicals.
Global ecological role / Function for climate change
"Over past 20 years (2021), the Brazilian Amazon emitted 13% more CO
2 than it absorbed".
Amazon vegetation holds around 56.8 billion metric tons of carbon above ground. The slash and burn cycle is causing the Amazon to release more carbon then it takes in.
The Amazon Basin holds 10% of the worlds biodiversity and about 15% of the worlds river discharge. The Amazon functions as a carbon sink due to photosynthesis where carbon dioxide is converted into oxygen. They role the vegetation plays in the water cycle is very important. 50% to 80% of the water remains locked within the basin due to the complex role vegetation, rivers and the atmosphere play with each other. Without trees the Amazon Basin's ability to hold onto the water will disappear and will lead to Desertification.
"Amazon biodiversity also plays a critical role as part of global systems, influencing the global carbon cycle and thus climate change, as well as hemispheric hydrological systems, serving as an important anchor for South American climate and rainfall. It also produces 20% oxygen of the Earth."
See also
-
Amazon biome
-
Amazon Cooperation Treaty Organization
-
Amazon Conservation Association
-
Amazon Conservation Team
-
Deforestation of the Amazon rainforest
-
Llanos de Moxos
-
Llanos de Moxos (archaeology)
-
Ucayali Peneplain
-
Pre-Columbian agriculture in the Amazon Basin
Further reading
-
Acker, Antoine.
target="_blank" rel="nofollow"> "Amazon" (2015). Center for InterAmerican Studies, University Bielefeld.
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External links
