The –TapajóMadeira-Tapajós moist forests (NT0135) is an ecoregion in the Amazon basin. It is part of the Amazon biome. The ecoregion extends southwest from the Amazon River between its large Madeira and Tapajós tributaries, and crosses the border into Bolivia. In the south it transitions into the cerrado biome of Mato Grosso. In the state of Rondônia it contains some of the most degraded land of the Amazon basin.
Location
The Madeira-Tapajós moist forests cover an area of . They stretch in a southwest direction through Brazil from the Amazon into northeast Bolivia. The ecoregion covers parts of the states of Amazonas, Rondônia and Mato Grosso in Brazil, and part of the Beni Department in Bolivia.
The ecoregion covers the interfluvial region between the Madeira River to the west and the Tapajós rivers to the east, two large tributaries of the Amazon to the north. Above the sources of the Tapajós the ecoregion extends south to the Guaporé River basin. The large rivers prevent the spread of flora and fauna. Thus the white-fronted capuchin (Cebus albifrons) and hairy saki (Pithecia hirsuta) are found west of the Tapajós, while the white-nosed saki (Chiropotes albinasus) is only found east of the river. In the south the bounds of the ecoregion are defined by distinct changes in vegetation, with the transition to Mato Grosso tropical dry forests in the southeast and to the Beni savanna and later the Chiquitano dry forests in the southeast.
To the northwest the ecoregion is separated from the Purus-Madeira moist forests by the Madeira River, which has Monte Alegre várzea along much of its length. The várzea extends along the Amazon River on the north of the ecoregion. To the east it is separated by the Tapajós river from the Tapajós–Xingu moist forests ecoregion. Further south along its southeast boundary it adjoins the Mato Grosso seasonal forests, Cerrado and Chiquitano dry forests ecoregions. In the southwest it adjoins the Southwest Amazon moist forests and Beni savanna ecoregions.
Physical
Most of the ecoregion is below in elevation. At its northern boundary on the Amazon river the elevation is above sea level. The ecoregion south of the river covers part of the low, flat Amazon basin, and rises gradually to the south and east to uplifted parts of the old Brazilian Shield. The southern part of the ecoregion contains the mountainous Parecis plateau (Chapada dos Parecis). The land rises to at the tallest peak of the Parecis plateau. The terrain here consists of table mountains with rocky meadows and semi-deciduous open submontane forest and woodland savanna.
The Madeira River is a sediment-rich whitewater river. The clearwater Tapajós, which rises in the ancient and well-weathered Brazilian Shield and follows a fixed course, does not carry sediment. Other large rivers in the region are the Maués Açu, Aripuanã and Canumã. The Parecis plateau's main rivers are the Ji-Paraná, Juruena, Papagaio, do Sangue and Guaporé.
Ecology
The ecoregion is in the Neotropical realm and the tropical and subtropical moist broadleaf forests biome.
Climate
The Köppen climate classification is "Am" equatorial, monsoonal. Annual rainfall is in most of the region, with less than along the north and south boundaries. Along the middle Madeira rainfall increases to . In the center of the region temperatures are relatively constant year round. They range from and average . In the humid lowland areas temperatures average , while in the mountains they average .
Flora
Vegetation includes dense lowland rainforest, dense submontane rainforest, open submontane rainforest and woodland savanna. There is seasonally flooded várzea forest in the Monte Alegre Várzea ecoregion along Madeira. There is white sand flooded igapó forest along the clearwater Tapajós and Aripuanã rivers, with large trees such as Triplaris surinamensis, Piranhea trifoliata, Copaifera martii and Alchornea castaneifolia. The flooded forest is somewhat more open than the surrounding terra firme forest. On the upper Madeira and Tapajós there are large areas of campina, white sand grasslands.