Most of the 7 million of km2 of the Amazon Forest is constituted by a forest of firm earth. This is a forest that is never flooded and it is spread on a great plain of up to 130-200 altitude meters, until the sopés of the mountains. The great plain corresponds to the sediments left by the lake " Belterra ", that it occupied most of the Amazon basin during Mioceno and Plioceno, between 25 thousand and 1,8 million years ago. The silte and the argilas deposited in this old lake were submitted to a soft movement of elevation epirogenético, while you Walk them they rose and the modern rivers began to dig its beds. The three types of amazon forests appeared like this: the Andean mountainous forests, the forests of firm earth and the flooded fluvial forests, the two last in Brazilian Amazônia.
The climatic flotations of Pleistoceno showed in a repeated succession of climates I cold-evaporate - hot-humid - hot-dry. The last phase cold-drought date of 18 thousand to 12 thousand years ago, when the climate of Amazônia was semi-arid, with medium temperature lowered for up to 5ºC. Soon after, there was the return of the hot-humid climate, that arrives at the maximum around 7 thousand years ago. Ever since, and with several oscillations of smaller load, we lived a climate relatively hot-dry.
Very important it was the fact that during the semi-arid phases, the great forest of firm earth one found divided and broken into fragments by open vegetable formations, of the closed type, caatingas and campinaranas, all better one adapted to the dry climate. The forest survived in " refuges ", placed in the areas of higher soils and with better provisioning hídrico. When returning the most humid climate, the forest he/she expanded again, in detriment of the vegetation of the closed ones. Nowadays, the closed survives in its own " refuges ", inside of the immensity of the forests of firm earth. This flotation process will repeat without a doubt, unless the man interferes in the situation.
The forest of firm earth has countless adaptations to the poverty in nutrients of its loamy soils and podzólicos. The trees that compose it are capable to provision with nitratos through bacterias fixadoras of nitrogen, that are tied up to its rootses. Besides, a great variety of mushrooms also simbiontes of the rootses, called micorrizas, recycles the organic material quickly before this to be leached. The serrapilheira (formed by leaves and other vegetable detritos that drop to the soil) it is recycled quickly by the rich fauna of insects, especially besouros, ants and cupins. The insects constitute most of the animal biomassa in the forest of firm earth.
This forest, especially rich in aráceas epífitas, it is, compared to the Atlantic forest, relatively poor in bromélias and orchids. Among these plants epífitas they are the mirmecófitas, plants that you/they live in narrow symbiosis with the ants. In the sub-forest of the forest they especially stand out the palm trees and the cipós. The great samambaias is rare.
The macrofauna of the ground of the forest is relatively poor. The several toads and pererecas there found they present several adaptations to guarantee the necessary water for the development of the girinos. Some great mammals, such as the tapirs, the cathetus and the jaw, as well as the mutuns and the inhambus, among the birds of the ground, they deserve prominence. Close to the ground of the forest also meets a lot of birds " papa-ants ", that remove profit of the enormous migrations of correição ants.
The great animal diversity meets in the cups of the trees between 30 and 50 height meters, an atmosphere of difficult access for the researcher. There it is rich the fauna of birds, as parrots, toucans and prick-sticks. Especially good-looking they are the pavãozinho of Pará and the gypsy. Among the mammals of the cups the marsupials, the bats, the rodents and the monkeys prevail. The primates possess niches well differentiated. The bugio is of the day and he/she feeds of preference with leaves. The monkey of the night Aotus is the only active monkey during the night. The sauins, voracious insetívoros, possesses several species and subspecieses that differ for the coloring and it forms of the faces. Beside the classic polinizadores - bees, butterflies and birds - the monkeys of the Amazon Forest also have a prominence paper as polinizadores. The birds, the bats and the monkeys frugívoros of the forest of firm earth have an important paper of disseminating the fruits and seeds of the trees.
The species and subspecieses of monkeys, laziness, squirrels and another are frequently separated by the great tributary rivers of the river Amazonas. The units biogeográficas formed by the basins of these rivers explains the great bioversidade of the amazon biota partly. Besides, we can assail forest areas that served as refuge to the several populations differentiated during the periods of arid climate of the past, above mentioned, when big areas of closed broke into fragments the Amazon Forest. Nowadays, the uncontrolled desmatamento is breaking into fragments the forest of firm earth. Without the necessary cares, counties whole faunísticas and old especiação centers take the risk of they be for ever obliterated.
The flooded forests are within reach of the annual enchentes of the river Amazonas and of its tributary ones closer. The flotations of the level of the water can arrive to 10 meters or more. Of March to September, great spaces of forest riverside are flooded. The plants and the animals of the amazon flooded forest live in function of its several special adaptations to survive during the enchentes.
The amazon waters possess different characteristics, resultants of the geology of its fluvial basins. The called rivers of rivers of white water or it darkens, as Solimões or him Wood, they travel rich lands in minerals and organic suspensions. The called rivers of black water, as the Black, originating from of poor sandy lands in minerals, they are transparent and colorings in brown for the substances húmicas. They also exist rivers of clear waters, like Tapajós, that are born in the areas of the old continental shields, also poor in minerals and nutritious.
The forests taken a bath by the white waters be call várzea forests and taken a bath them for the black and clear waters, of igapós forests. The vegetation of the várzea is much richer than the vegetation of the igapós, because of the fertility of the white waters and of the soils aluvionais for them brought. The same is verified with the fauna of the two types of forests, especially with the aquatic biota. The rivers of white water are rich in fish, while the rivers of black water are " rivers of the hunger ". The areas where the two types of waters are mixed, as the area close to Manaus, they are especially considered rich.
The trees of the flooded forests have several morphologic and physiologic adaptations for they live partially submerged, as breathing rootses and sapopembas. The trees are practically poor in plants epífitas and the sub-forest inexiste. In its place a rich herbaceous flora exists, as the capim-mori, the canarana and the wild rice. In the station of the enchentes, the capim stands out and it forms true flotation islands. Other flotation plants, such as the victory-royal and the aguapé, they also accompany the level of the waters.
The mammals of the flooded forests - tapirs, capivaras and other - they are all good swimmers. Until the laziness they are capable to swim. The fauna of monkeys and of another mammals arborícolas in general is poor, compared with the fauna of the firm earth. In the várzea rivers they meet, even so, several species of aquatic mammals, as the botos, the fish ox, the ariranha and the otters. The primates' fauna is very reduced. The vegetarian fish ox and the botos predadores are, however, very rare in the black and clear waters of the igapós, poor in aquatic vegetation and little piscosas.
In the avifauna relatively poor of the igapós forests the aquatic birds prevail, such as the herons, biguás, jaçanãs, mucurungos and ducks.
The waters of the flooded forests are rich in aquatic reptiles. The turtles are important herbivores of the aquatic vegetation and they are very hunted. The true turtle (Podocnemis expansa) it is in extinction danger; the big head (P. dumeriliana) and the tracajá (P.unifilis) they are also very appreciated by the hunters. The cágados Phrynops is found with more frequency in the rapidses. Among the alligators, the jacaretinga (Palaeosuchus trigonatus), gender with an only endemic species in Amazônia, it is threatened of extinction. The alligator-açu (Melanosuchus niger) it is the common alligator in the area. Several authors attribute to the alligators predadores an important paper of " regulators " in the várzea. The great amazon jibóia also deserves to be mentioned.
In Amazônia they live around 10 thousand species of fish. Here, we mentioned just some species linked to the flood forest. They are these the fish frugívoros that you/they developed in narrow co-evolution with the trees and amazon bushes: the fruits drop in the water, they are gobbled by the fish and the resistant seeds to the gastric enzymes they are transported for far. Several fish, especially the one of the great order of Characinoidea, present teethings specialized for certain types of fruits. The tambaqui (Collosoma macropomum) it is a specialist comedor of the fruits of the Hevea spruceana. Pacus, of the goods Mylossoma, Myleus and Broco, are also important comedores of fruits of palm trees, embaúbas and other trees. The piranheira is a plant preferred by some piranhas species. The dispersion of the plants for the fish of the várzea and of the igapós he/she has an importance comparable to the one of the classic dispersion of seeds for the birds and mammals in the forests of firm earth. The tambaqui and the pacus, as well as the pirarucu (Arapaima gigas), they are the fish of larger commercial importance in Amazônia. Nothing illustrates the important ecological paper of the frugivoria of the fish better. The tambaqui is very sought by tourist fishermen.
The fish frugívoros constitutes only one of the types of fish in the várzea, but their paper is particularly important in the black and clear waters. Due to the excessive poverty of those waters in fito and zooplâncton, they are the trees that supply most of the victuals. Even so, the fish of the Black river are of smaller sizes than its coespecíficos in the river Solimões. The cardumes is also smaller.
The fauna of insects is mainly linked to the flotation vegetation. The little cupins species and of ants they accompany the ascent and gone down her of the waters along the logs of the trees. Several types of insects live on the flotation vegetation, while in the waters enormous populations of mosquitos and other irritating dipterros are created. The rivers of black water are exempted of this I flagellate.

The flooded forests contain several species of trees of economic usefulness, besides law wood. The seringueira, sip it, the andiouba, the macaranduba, the buriti and the tiucum produce rubber, victuals, oils, resins and fibers of economic importance. The várzeas is especially rich and productive. There they met the great indigenous concentrations and now great projects are developed agriculture-pecuários and industrial.
Specific of the igapós of sandy soils and of black water they are the piranheira (Piranhea trifoliata), the oeirana (Alchornea castaniifolia), several species of Inga and of Eugenia, the palm trees Copaifera martii (copaíba) and Leopoldinia. Some trees have great resistance to the lingering enchentes, such as the Myrciaria dubia, the Eugenia inundata (igapó araçá) and, finally, the Salix humboldtiana, that survive several years of permanent submersion.
A lot of species of the várzea are threatened of extinction due to the fast development of the urban areas, of the construction of you dam, of the pollution with the mercury of the claims etc. The hunt and the fishing desregulada in the várzea already placed in risk the existence of several aquatic vertebrates of great load. The list of the species in extinction is headed by the botos, fish ox, ariranha, true turtle, jacaretinga and others. Among the threatened fish we highlighted the pirarucu, the largest fish of fresh water of the world.
The high productivity of the várzea facilitated a dense indigenous povoação to the time of the discovery. The margins of the great river sheltered many villages with thousands of inhabitants. The density populacional reached 14,6 people for square kilometer. The riverine ones cultivated corn and cassava in the rich soil aluvional, they collected wild rice and usufruíam of rich fishing. These Indian ones had an organization of social classes and they used slaves' work.
The rivers of black water, on the contrary, considered " hunger " rivers, they were historically not very inhabited. Even so, for the lack of dípteros molestadores, as mosquitos, borrachudos and mutucas, the new settlers preferred to live in the margins of the rivers of black water. For a short period, the capital of the area went to Barcelos, in the medium Black river, but it moved quickly to Manaus, close to the rich várzea in fish. It is still necessary to consider that the fertile soils in Amazônia are the várzea soils, exactly where the great urban centers tend locating, with its bases of provisioning.
An ecological station is placed entirely in the atmosphere of the igapós: it is the Federal Ecological Station of the archipelago of Anavilhanas, in the bass Black river. In the enchentes, the archipelago of hundreds of islands is submerged practically. The laboratory of research of the Station stays flotation homes that also accompany the level of the waters. Another station, Mamirauá, is placed in the várzea, close to Tefé. The great center of researches of Amazônia (INPA), in Manaus, and the Museu Goeldi, in Belém, they maintain several reservations and research areas in the forests of firm earth. In Santarém he/she meets a great center of researches piscívoras.