The Amazon Rainforest: The World's Largest Rainforest

By Rhett A. Butler [Last update June 4, 2020]

The Amazon River Basin is home to the largest rainforest on Earth. The basin -- roughly the size of the forty-eight contiguous United States -- covers some 40 percent of the South American continent and includes parts of eight South American countries: Brazil, Bolivia, Peru, Ecuador, Colombia, Venezuela, Guyana, and Suriname, as well as French Guiana, a department of France.

Reflecting environmental conditions as well as past human influence, the Amazon is made up of a mosaic of ecosystems and vegetation types including rainforests, seasonal forests, deciduous forests, flooded forests, and savannas.

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 river.

The river system is the lifeline of the forest and its history plays an important part in the development of its rainforests.

WHERE THE AMAZON RANKS AMONG GLOBAL RAINFORESTS

The Amazon is the world's biggest rainforest, larger than the next two largest rainforests — in the Congo Basin and Indonesia — combined.

As of 2020, the Amazon has 526 million hectares of primary forest, which accounts for nearly 84% of the region's 629 million hectares of total tree cover. By comparison, the Congo Basin has around 168 million hectares of primary forest and 288 million hectares of tree cover, while the combined tropical areas of Indonesia, Papua New Guinea, Malaysia, and Australia have 120 million hectares of primary forest and 216 million hectares of tree cover.

THE HISTORY OF THE AMAZON RAINFOREST

At one time Amazon River flowed westward, perhaps as part of a proto-Congo river system from the interior of present day Africa when the continents were joined as part of Gondwana. Fifteen million years ago, the Andes were formed by the collision of the South American plate with the Nazca plate. The rise of the Andes and the linkage of the Brazilian and Guyana bedrock shields, blocked the river and caused the Amazon to become a vast inland sea. Gradually this inland sea became a massive swampy, freshwater lake and the marine inhabitants adapted to life in freshwater. For example, over 20 species of stingray, most closely related to those found in the Pacific Ocean, can be found today in the freshwaters of the Amazon.

About ten million years ago, waters worked through the sandstone to the west and the Amazon began to flow eastward. At this time the Amazon rainforest was born. During the Ice Age, sea levels dropped and the great Amazon lake rapidly drained and became a river. Three million years later, the ocean level receded enough to expose the Central American isthmus and allow mass migration of mammal species between the Americas.

The Ice Ages caused tropical rainforest around the world to retreat. Although debated, it is believed that much of the Amazon reverted to savanna and montane forest (see Ice Ages and Glaciation). Savanna divided patches of rainforest into "islands" and separated existing species for periods long enough to allow genetic differentiation (a similar rainforest retreat took place in Africa. Delta core samples suggest that even the mighty Congo watershed was void of rainforest at this time). When the ice ages ended, the forest was again joined and the species that were once one had diverged significantly enough to be constitute designation as separate species, adding to the tremendous diversity of the region. About 6000 years ago, sea levels rose about 130 meters, once again causing the river to be inundated like a long, giant freshwater lake.

Note: Human populations have shaped the biodiversity of the Amazon. See Amazon people for more.

THE AMAZON RIVER TODAY

Today the Amazon River is the most voluminous river on Earth, carrying more than five times the volume of the Congo or twelve times that of the Mississippi, draining an area nearly the size of the forty-eight contiguous United States. During the high water season, the river's mouth may be 300 miles wide and every day up to 18 billion cubic meters (635 billion cubic feet) of water flow into the Atlantic. That discharge, equivalent to 209,000 cubic meters of water per second (7.3 million cubic feet/sec), could fill over 7.2 million Olympic swimming pools per day or supply New York City's freshwater needs for nine years.

The force of the current -- from sheer water volume alone -- causes Amazon River water to continue flowing 125 miles out to sea before mixing with Atlantic salt water. Early sailors could drink freshwater out of the ocean before sighting the South American continent.

The river current carries tons of suspended sediment all the way from the Andes and gives the river a characteristic muddy whitewater appearance. It is calculated that 106 million cubic feet of suspended sediment are swept into the ocean each day. The result from the silt deposited at the mouth of the Amazon is Majaro island, a river island about the size of Switzerland.

The Amazon's influence on the movement of moisture extends beyond the water that flows down the Amazon river. The trees of the Amazon rainforest pump vast quantities of water vapor into the atmosphere every day via transpiration. While much of this water falls locally as rain, some of this moisture is carried by airflows across other parts of the continent, including the agricultural heartland of South America to the south. This movement has been likened to "flying rivers". By one estimate, 70% of Brazil's gross national product comes from areas that receive rainfall generated by the Amazon rainforest.

THE AMAZON RAINFOREST

While the Amazon Basin is home to the world's largest tropical rainforest, the region consists of myriad other ecosystems ranging from natural savanna to swamps. Even the rainforest itself is highly variable, tree diversity and structure varying depending on soil type, history, drainage, elevation, and other factors. This is discussed at greater length in the Amazon rainforest ecology section.

AMAZON BIODIVERSITY

The Amazon is home to more species of plants and animals than any other terrestrial ecosystem on the planet -- perhaps 30 percent of the world's species are found there. The following numbers represent a sampling of its astounding levels of biodiversity:

• 40,000 plant species
• 16,000 tree species
• 3,000 fish species
• 1,300 birds
• 430+ mammals
• 1,000+ amphibians
• 400+ reptiles

THE CHANGING AMAZON RAINFOREST

The Amazon has a long history of human settlement, but in recent decades the pace of change has accelerated due to an increase in human population, the introduction of mechanized agriculture, and integration of the Amazon region into the global economy. Vast quantities of commodities produced in the Amazon — cattle beef and leather, timber, soy, oil and gas, and minerals, to name a few — are exported today to China, Europe, the U.S., Russia, and other countries. This shift has had substantial impacts on the Amazon.

This transition from a remote backwater to a cog in the global economy has resulted in large-scale deforestation and forest degradation in the Amazon — more than 1.4 million hectares of forest have been cleared since the 1970s. An even larger area has been affected by selective logging and forest fires.

Conversion for cattle grazing is the biggest single direct driver of deforestation. In Brazil, more than 60 percent of cleared land ends up as pasture, most of which has low productivity, supporting less than one head per hectare. Across much of the Amazon, the primary objective for cattle ranching is to establish land claims, rather than produce beef or leather. But market-oriented cattle production has nonetheless expanded rapidly during the past decade.

Industrial agricultural production, especially soy farms, has also been an important driver of deforestation since the early 1990s. However since 2006 the Brazil soy industry has had a moratorium on new forest clearing for soy. The moratorium was a direct result of a Greenpeace campaign.

Mining, subsistence agriculture, dams, urban expansion, agricultural fires, and timber plantations also result in significant forest loss in the Amazon. Logging is the primary driver of forest disturbance and studies have shown that logged-over forests — even when selectively harvested — have a much higher likelihood of eventual deforestation. Logging roads grant access to farmers and ranchers to previous inaccessible forest areas.

Deforestation isn't the only reason the Amazon is changing. Global climate change is having major impacts on the Amazon rainforest. Higher temperatures in the tropical Atlantic reduce rainfall across large extents of the Amazon, causing drought and increasing the susceptibility of the rainforest to fire. Computer models suggest that if current rates of warming continue, much of the Amazon could transition from rainforest to savanna, especially in the southern parts of the region. Such a shift could have dramatic economic and ecological impacts, including affecting rainfall that currently feeds regions that generate 70 percent of South America's GDP and triggering enormous carbon emissions from forest die-off. These emissions could further worsen climate change.

PROTECTING THE AMAZON RAINFOREST

While destruction of the Amazon rainforest is ongoing, the overall rate of deforestation rate in the region dropped between the mid-2000s and mid-2010s, mostly due to to the sharp decline in forest clearing in Brazil. However deforestation has been steadily rising in the region in more recent years.

Brazil's decline in its deforestation rate between 2004 and 2012 was attributed to several factors, some of which it controls, some of which it doesn't. Between 2000 and 2010 Brazil established the world's largest network of protected areas, the majority of which are located in the Amazon region. In 2004, the government implemented a deforestation reduction program which included improved law enforcement, satellite monitoring, and the provision of financial incentives for respecting environmental laws. Independent public prosecutors offices played a particularly important role in pursing illegal activities in the Brazilian Amazon. The private sector also got involved, especially after 2006 when major crushers established a moratorium on new deforestation for soy. That soy moratorium was followed by the "Cattle Agreement", which major slaughterhouses and beef processors committed to source cattle only from areas where environmental laws were being respected.

However these conservation initiatives started to break down in the Brazilian Amazon in the mid-2010s. Major cattle producers circumvented the rules through livestock laundering, while financial incentives for conserving forests failed to materialize at the expected scale needed to change landowners' behavior. The Temer and Bolsonaro Administrations dismantled environmental regulations, reduced environmental law enforcement, stripped conservation areas and indigenous territories of protections, and encouraged a wide range of industries (mining, logging, agribusiness) to expand extraction and conversion in the Amazon. In 2019, deforestation in the Brazilian started accelerating rapidly.

THE LATEST AMAZON RAINFOREST NEWS

Amazonian ecosystems and peoples on the brink – it is time for a new vision (commentary) (18 Oct 2021 21:07:33 +0000)
- Mercedes Bustamante — a Professor at the University of Brasilia, member of the Brazilian Academy of Sciences, and a lead scientist for the Science Panel for the Amazon — says the world needs to announce a “code red” for the Amazon due to increasing threats to the world’s largest rainforest.
- Bustamante cites evidence gathered in a new synthesis of the scientific knowledge on Amazonian socio-ecological systems, which “summarizes how ecosystems and human populations coevolved in this unique region and documents the unprecedented changes the Amazon has witnessed in recent years and their profound impacts on the continental and global environment.”
- “Saving existing forests from continued deforestation and degradation and restoring ecosystems is one of the most urgent tasks of our time to preserve the Amazon and its people and address the global risk and impacts of climate change,” Bustamante writes.
- This post is a commentary. The views expressed are those of the author, not necessarily Mongabay.

Conservation will only scale when non-conservationists see its value, says James Deutsch (12 Oct 2021 13:56:30 +0000)
- Last month, Rainforest Trust committed $500 million to a $5 billion pledge to conserve biodiversity.
- The scale of Rainforest Trust’s commitment was surprising to some in the conservation world: just a decade ago, the Virginia-based group had an annual budget in the low single-digits millions. Now the organization is aiming to raise $50 million a year over the next ten years — an incredible rate of expansion.
- Rainforest Trust is undertaking that ambitious target just 18 months after undergoing a major leadership transition: In April 2020, it appointed James Deutsch as CEO. Deutsch says the pledge will push Rainforest Trust to double down on its mission of creating and expanding protected and conserved areas through partnerships with other organizations. Rainforest Trust rallies the resources; partners lead the work on the ground.
- Deutsch spoke about the pledge and a range of other topics during a recent interview with Mongabay founder Rhett A. Butler.

Brazil reports increase in Amazon logging (11 Oct 2021 01:34:47 +0000)
- Selective forest cutting in the Amazon is on the rise, according to data released on Friday by the Brazilian government.
- INPE reported a 77% increase in the rate of cutting that’s typically associated with logging, from 646 square kilometers in September 2020 to 1,145 square kilometers last month. Selective cutting in the region currently stands at the highest level in at least five years.
- The rise in logging is significant because logged areas in the Amazon are more likely to be eventually deforested. Selectively logged forests also face higher fire risk due to drier conditions relative to intact rainforests.

Facebook to block illegal sales of protected Amazon rainforest lands (08 Oct 2021 23:54:44 +0000)
- On Friday, Facebook announced it would crack down on the illegal sales of protected Amazon rainforest land via its platform, according to a blog post by the company.
- The move comes after a BBC investigation found that the company’s Marketplace product was being used to broker sales of protected lands, including Indigenous territories and national forest reserves.
- Experts raised doubts about the effectiveness of Facebook’s approach since the social media company doesn’t require users to specify the coordinates of the land they are selling.
- “If they don’t make it mandatory for sellers to provide the location of the area on sale, any attempt at blocking them will be flawed,” Brenda Brito, a Brazilian lawyer and scientist told BBC News. “They may have the best database in the world, but if they don’t have some geo-location reference, it won’t work.”

Brazil leads Amazon in forest loss this year, Indigenous and protected areas hold out (06 Oct 2021 14:53:38 +0000)
- Satellite imagery brings us a first look at this year’s deforestation hotspots, areas where forest cover was lost in high densities across the Amazon, amounting to more than 860,000 hectares (2.1 million acres).
- The majority of deforestation (76%) occurred in Brazil and was clustered around roads, according to a recent report from Amazon Conservation’s Monitoring of the Andean Amazon Project (MAAP); many of the areas deforested this year in Brazil have also burned.
- In Colombia, deforestation hotspots this year were in and around numerous protected areas, including Tinigua and Chiribiquete national parks, as well as Indigenous reserves, particularly Yari-Yaguara II and Nukak Maku; in Peru, rice farming and a new Mennonite colony drove recent deforestation.
- Of primary forests loss across the western Amazon between 2017 and 2020, three-quarters were outside protected areas and Indigenous territories, highlighting the importance of these key land use designations for safeguarding the remaining Amazon rainforest.

New transport infrastructure is opening the Amazon to global commerce (27 Sep 2021 22:03:46 +0000)
- Tim Killeen provides an update on the state of the Amazon in his new book “A Perfect Storm in the Amazon Wilderness – Success and Failure in the Fight to save an Ecosystem of Critical Importance to the Planet.”
- The book provides an overview of the topics most relevant to the conservation of the Amazon’s biodiversity, ecosystem services and Indigenous cultures, as well as a description of the conventional and sustainable development models vying for space within the regional economy.
- Mongabay will publish excerpts from the Killeen’s book, which will be released by The White Horse Press in serial format over the course of the next year. In this second installment, we provide a section from Chapter Two: “Global Competition Drives Bulk Transport Systems”.
- This post is an except from a book. The views expressed are those of the author, not necessarily Mongabay.

Countering Bolsonaro’s UN speech, Greenpeace releases Amazon deforestation photos (21 Sep 2021 23:59:56 +0000)
- Hours after Brazilian President Jair Bolsonaro painted a rosy picture of his administration’s environmental record during a United Nations speech, Greenpeace and other environmental groups released a set of photos showing continued deforestation and fires in Earth’s largest rainforest.
- Speaking to the U.N. General Assembly in New York on Tuesday, Brazilian President Jair Bolsonaro cited a 32 percent reduction in deforestation in the month of August relative to a year ago, the country’s near decade-old Forest Code, and lands set aside as Indigenous territories — which he’s fought to undermine and dismantle — as evidence of Brazil’s contributions toward mitigating climate change.
- But activists pushed back on Bolsonaro’s statement, noting rising deforestation in the Amazon and his administration’s rollback of environmental laws and law enforcement, while publishing dramatic images captured in two Amazon states between September 14 and 17.
- Brazil does have some of the strongest forest protection laws on the books among major tropical forest nations, but enforcement has been lax, especially under Bolsonaro, when the deforestation rate in the Amazon has climbed to the highest level since 2008. Bolsonaro’s reference to one month of deforestation data doesn’t reflect the trend of rising deforestation that he’s presided over since taking office in January 2019.

Fires in the Amazon have already impacted 90% of plant and animal species (21 Sep 2021 16:23:22 +0000)
- New study addresses the effects of fires on biodiversity loss in the world’s largest forest during the last two decades.
- Researchers measured the impacts on the habitats of 14,000 species of plants and animals, finding that 93 to 95% suffered some consequence of the fires.
- Primates were the most affected, as they depend on trees for movement, food and shelter. Rare and endemic species with restricted habitats suffered the strongest impacts.
- The study assessed two decades of fires between 2001 and 2019 and confirmed the impact of environmental policies on deforestation cycles in the Amazon; law enforcement was concluded to have direct impact on the extent and volume of fires.

Illegal logging reaches Amazon’s untouched core, ‘terrifying’ research shows (15 Sep 2021 21:45:33 +0000)
- Satellite imagery shows that logging activity is spreading from peripheral areas of the Amazon toward the rainforest’s core, according to groundbreaking research.
- The satellite-based mapping of seven of Brazil’s nine Amazonian states showed a “terrifying” pattern of logging advance that cleared an area three times the size of the city of São Paulo between August 2019 and July 2020 alone.
- At the state level, lack of transparency in logging data makes it impossible to calculate how much of the timber production is illegal, experts say.
- Evidence of cutting in Indigenous reserves and conservation units — where logging is prohibited — make clear that illegal logging accounts for much of the activity, according to the report.

Deforestation sweeps national park in Brazil as land speculators advance (10 Sep 2021 23:56:11 +0000)
- Between January and early September, 3,542 deforestation alerts have been confirmed in primary forest within Campos Amazônicos National Park, according to satellite data, representing a 37% jump over the average amount of forest loss for the previous five years.
- Much of the occupation of the Campos Amazônicos park is happening through illegitimate land claims, fueled by hopes that protections on the park may be loosened in the future, environmentalists say. Even though the park is under federal protection, this hasn’t stopped invaders from falsely registering slices of it as their property.
- Environmentalists warn the social and environmental impacts could be devastating. Campos Amazônicos wraps around the Tenharim do Igarapé Preto Indigenous Reserve, which was until recently under attack by illegal miners who descended on the territory in search of cassiterite; sources say the fresh incursions into Campos Amazônicos could put the area back at risk.
- The park also holds one of the most striking enclaves of cerrado in the Amazon rainforest, housing stretches of shrubs, grasslands and dry forest typical of the savanna biome. Campos Amazônicos is also part of the Southern Amazon Conservation Corridor that represents one of the best-preserved stretches of the rainforest.

PICTURES OF THE AMAZON RAINFOREST