The Instituto Brasileiro do Meio Ambiente (IBAMA) is the federal agency in charge of studying and monitoring Brazil’s natural environment. IBAMA’s researchers have recognized seven distinct ecosystems within Brazil : the Amazonian rainforest, the Caatinga, the Atlantic rainforest, the coastal region, the Cerrado, the Pantanal wetlands, and the southern plains.
The world’s largest tropical rainforest, the Amazon  is also one of the world’s richest sources of biological diversity. It’s home to 40,000 plant species, 2,000 birds and mammals, 3,000 fish, and 2.5 million insect species—and these are merely the species that have been identified. Despite human encroachment upon the forest, the majority of it is uninhabited. Furthermore, with the Amazon River itself boasting thousands of tributaries, there are still many areas that remain remote and completely unknown to humans.
Rainforests exist in regions that receive at least 2 meters (6.5 feet) of annual rainfall. In the Amazon, this accounts for humidity levels that are usually higher than 80 percent. Flooding of the Amazon itself and its tributaries can cause water levels to rise by as much as 15 meters (49 feet), transforming forest floors into lakes and driving most wildlife—butterflies, birds, sloths, and monkeys—up into the highest tree canopies. Some parts of the forest, known as igapó, are permanently flooded, whereas others, known as várzea are only flooded seasonally.
The Amazon Basin holds about 17 percent of the world’s fresh water. With a length of 6,400 kilometers (4,000 miles), the mighty Rio Amazonas is the largest river in Brazil —and the greatest river in the world because it carries 119,000 cubic meters (4.2 million cubic feet) of water into the sea every second. Beginning in Peru , the river flows eastward until it empties into the Atlantic Ocean near the city of Belém . All in all, its more than 1,000 tributaries add up to more than 7,047,000 square kilometers (2,722,000 square miles) of water. The Amazon is also home to Brazil’s highest mountain, Pico Neblina. Located near the Venezuelan border, it rises to a height of 3,014 meters (9,888 feet).
A marked contrast to the lushness of the Amazon is the parched dryness of the scrubby Caatinga vegetation that characterizes much of the interior of northeastern Brazil, an area known as the Sertão. Caatinga covers approximately 11 percent of Brazilian territory. Although the Sertão’s legendary droughts and tales of hardship have led many Brazilians to conjure up images of an inhospitable moonscape where only cacti grow, the semi-arid Caatinga actually possesses a wet season as well as a dry season. During the latter, rivers dry up, leaves disappear, and cracks appear in the sun-baked earth. However, when the torrential rains do come (in the summer months), the low scrub and thorn trees suddenly burst into green.
When the first Portuguese arrived in Brazil , a dense Atlantic forest, the Mata Atlântica, blanketed the entire coastline from Rio Grande do Norte  in the north to Rio Grande do Sul  in the south. Stretching west by an average of 200 kilometers (124 miles) into the interior, this ancient rainforest (far older than the Amazon) measured 1 million square kilometers (621,000 square miles). However, five centuries of brazilwood extraction, sugar and coffee cultivation, farming, logging, urbanization, and industrialization have taken their toll.
Today, only 7 percent of Mata Atlântica remains in patches (notably in southern Bahia , Rio de Janeiro , São Paulo , and Paraná ). However, the surviving forest is surprisingly lush and rife with unique forms of flora and fauna unknown anywhere else in Brazil or the world. Rare mammals include the lion tamarin and woolly spider monkey (the largest primate in the Americas), while plant life includes rare bromeliads, orchids, ferns, and surviving specimens of pau brasil, the wood that lent Brazil its name. Thankfully, much of the remaining forest is now carefully preserved (at least in theory) as nature reserves and national parks.
Brazil boasts an enormous coastline that stretches 8,000 km (5,000 miles) and includes a vast array of interesting formations including rocky cliffs, enormous dunes, boulders, sandy coves, coastal plains, forests, and manguezais, or mangroves. Mangroves are unique systems that appear wherever a river flows into a bay or estuary. They extend along the coast as far north as Pará  and as far south as Santa Catarina . Soil rich with river sediment and organic matter nourishes the dense mangrove vegetation, which in turn attracts fish, storks and ibises, and shrimps, crabs, and mussels.
Traditionally, some local populations viewed mangroves as muddy, humid, unhygienic swamps. They tried to drain them or use them as garbage dumps. Only recently has their important role in maintaining the delicate equilibrium of marine life been recognized. As a result, many have become protected environments.
Southern Brazil, extending from Santa Catarina  into Rio Grande do Sul , is covered with a vast plain where low vegetation, mosses, and lichens thrive along with cacti and bromeliads. South- and westward, the plain gradually transforms into the grassy Pampas, a rolling green carpet studded with occasional cork and fig trees.
The vast highland plains of the Central-West region (known as the Planalto) that surround Brasília  and stretch west through Goiás  into Mato Grosso  and Mato Grosso do Sul  are covered with a distinctive type of vegetation known as Cerrado. Resembling the dry, scrubby, savannah-like landscapes of eastern Africa, Cerrado is a surprisingly rich and unique ecosystem, over 40 percent of whose roughly 10,000 plant species don’t exist anywhere else on Earth.
Aside from straw-colored grasses and scrubby bushes, characteristic vegetation ranges from thick-barked trees and primitive-looking buriti palms to blossoming ipê, jacaranda, and the ubiquitous pequi tree, whose spiky orange fruit is used in local cooking. Due to widespread clearing of the land for farming, more than half of this precious ecosystem has been destroyed.
While efforts have been taken in recent years to preserve considerable chunks of the Amazon and Atlantic rainforests, conservation strategies in the relatively unknown Cerrado are virtually nonexistent aside from a few existing nature reserves.
The world’s greatest inland wetlands, the Pantanal  is a vast plain that is constantly flooded with waters from the Andes, the Planalto, and the Rio Paraguai Basin. Extending from the Central-West states of Mato Grosso  and Mato Grosso do Sul  to Bolivia and Paraguay, the region measures 250,000 square kilometers (96,500 square miles) and covers an area larger than the United Kingdom. The Pantanal is actually a complex system fed by more than 100 rivers. Depending on the season, the entire region is drastically transformed.
The wet season, which lasts from November to March, is marked by rains and rising rivers, which turn the area into a vast aquarium dotted with islands. During this period, wildlife moves to higher ground and transportation is by boat only.
The “dry season,” which extends from April to October, is characterized by the slow draining of floodplains. Receding water leaves rich sediment behind where pasture sprouts. As a result, the area is ideal for cattle raising (the bovine population far outnumbers humans).
Instead of a distinctive flora and fauna of its own, the Pantanal has a lot of everything else—including plants and animals that are typical of the Amazon forest, the Cerrado, and even the Caatinga. Due to its relative seclusion, you’ll find wildlife in much greater numbers in the Pantanal than in the Amazon, making the region a not-to-be-missed mecca for wildlife enthusiasts as well as freshwater fishing aficionados.