Xingu-Tocantins-Araguaia moist forests

The Köppen climate classification is "Am": equatorial, monsoonal.[4] Temperatures are fairly steady throughout the year, slightly higher in April and slightly lower in July. Average temperatures range from 21 to 32 °C (70 to 90 °F), with a mean of 26.5 °C (79.7 °F).[4] The region is drier than the ecoregions further to the west. In the middle Xingu annual rainfall is 1,500 to 2,000 millimetres (59 to 79 in).[2] Elsewhere average annual precipitation is about 2,100 millimetres (83 in) Monthly precipitation ranges from 19.4 millimetres (0.76 in) in July to 335.4 millimetres (13.20 in) in March.[4]

The diverse terrain results in diverse flora and fauna, particularly on the richer soils, with many endemic species. Most of the original vegetation is evergreen tropical rainforest on terra firme. In the north there is lowland Amazon forest up to 40 metres (130 ft) high, graduating to dense submontane forest and then open submontane forest further south. There are fewer epiphytes and orchids in these forests than in the ecoregions further west. There are areas of liana forests on higher ground in the south and southeast and of forests dominated by babaçu palm (Attalea genus) and/or Brazil nut (Bertholletia excelsa). The stands of babaçu palms are thought to be originally planted by humans.[2] The blackwater river banks are lined with white-sand igapó flooded forests.[1] In the south the ecoregion is broken up by areas of savanna woodlands from the cerrado biome of the Central Brazilian Plateau.[2]

The liana forests cover large areas of comparatively rich soil. They are more open than the humid terra firme forest, with a lower canopy of 25 metres (82 ft) or less. They contain many huge lianas at all levels from the families Bignoniaceae, Fabaceae, Hippocrateaceae, Menispermaceae, Sapindaceae, and Malpighiaceae. They also hold large trees including Apuleia molaris, Bagassa guianensis, Caryocar villosum, Hymenaea parvifolia, Tetragastris altissima, Astronium graveolens, Astronium lecointei, Apuleia leiocarpa var. molaris, Sapium marmieri, Acacia polyphylla and Elizabetha. There are many endemic species such as Cenostigma tocantinum, Ziziphus itacaiunensis and Bauhinia bombaciflora. Typical trees in the middle Tocantins upland include Cenostigma tocantinum, Bombax tocantimumi, Bombax macrocalyx, Matisia bicolor, Strychnos melinoniana and Strychnos solimoesana. Swietenia macrophylla is found in the moist areas.[2]

Snake of genus Chironius in Carajás

There are 153 species of mammals, a relatively low number for the Amazon region. Of these 90 are bats and 21 are rodents. There are 8 species of primates including the white-nosed saki (Chiropotes albinasus), red-handed tamarin (Saguinus midas), red-bellied titi (Callicebus moloch), Azara's night monkey (Aotus azarae infulatus) and white-cheeked spider monkey (Ateles marginatus). The last two are endemic to this ecoregion and the Tapajós-Xingu moist forests to the west. Other species of mammals include white-lipped peccary (Tayassu pecari), collared peccary (Pecari tajacu), cougar (Puma concolor), jaguar (Panthera onca), South American tapir (Tapirus terrestris), brocket deer (genus Mazama), bare-tailed woolly opossum (Caluromys philander), and seven-banded armadillo (Dasypus septemcinctus).[2] Endangered mammals include white-cheeked spider monkey (Ateles marginatus), black bearded saki (Chiropotes satanas) and giant otter (Pteronura brasiliensis).[5]

527 species of birds have been recorded including many species of egret, heron, hawk and falcon along the rivers and meadows. Other birds include Brigida's woodcreeper (Hylexetastes perrotii brigidai), hyacinth macaw (Anodorhynchus hyacinthinus), scarlet macaw (Ara macao), many parrots (genera Amazona and Pionus) and parakeets (genera Aratinga, Pyrrhura and Brotogeris').[2] Endangered birds include green-thighed parrot (Pionites leucogaster), red-necked aracari (Pteroglossus bitorquatus) and yellow-bellied seedeater (Sporophila nigricollis).[5]

The rivers are home to spectacled caiman (Caiman crocodilus), black caiman (Melanosuchus niger), yellow-spotted river turtle (Podocnemis unifilis), Amazonian manatee (Trichechus inunguis), Amazon river dolphin (Inia geoffrensis) and tucuxi (Sotalia fluviatilis).[2]

Carajás Mine in the Carajás Mountains