Purus várzea

Purus várzea
Purus River to the north of the Mapinguari National Park
Ecology
Realm	Neotropical
Biome	Tropical and subtropical moist broadleaf forests – Amazon
Geography
Area	177,414.18 km2 (68,500.00 sq mi)
Countries	Colombia, Brazil
Coordinates	2°23′35″S 66°02′20″W / 2.393°S 66.039°W / -2.393; -66.039Coordinates: 2°23′35″S 66°02′20″W / 2.393°S 66.039°W / -2.393; -66.039

The Purus várzea (NT0156) is an ecoregion of seasonally flooded várzea forest in the central Amazon basin. It is part of the Amazon biome. The ecoregion is home to a vegetation adapted to floods of up to 12 metres (39 ft) that may last for eight months. There is a great variety of fish and birds, but relatively fewer mammals. Ground-dwelling mammals must migrate to higher ground during the flood season. Threats include logging, cattle farming, over-fishing and mercury pollution from gold mining.

The Purus várzea is a low-lying region of the central Amazon basin that is seasonally flooded. It covers 17,741,418 hectares (43,840,000 acres) of eastern Colombia and western Brazil. It extends along most of the Juruá, central Purus, and Caquetá (Japurá) rivers and their tributaries. In the east it reaches the confluence of the Japurá and Solimões Rivers. Urban centers in or around the region are Tefé, Tabatinga and Carauarí.

To the southeast the varzea adjoins the Purus-Madeira moist forests, and to the northeast it adjoins the Japurá-Solimões-Negro moist forests. Streams that flow through the Southwest Amazon moist forests, Solimões-Japurá moist forests and Caqueta moist forests to the west, and the Juruá-Purus moist forests in the central region all contain stretches of the varzea. The Monte Alegre várzea is downstream along the Solimões.

Altitudes range from 80 to 120 metres (260 to 390 ft). The forests are seasonally flooded by whitewater rivers, which carry suspended sediment washed from the eastern slopes of the Andes and organic material. Water levels rise by up to 12 metres (39 ft) in the flood period, which may last for eight months of the year. The soil is fertile, composed of sediments that have accumulated in the present Holocene epoch and that are renewed by the annual floods. The river course through the floodplain constantly shifts over time, creating oxbow lakes, levees, meander swales and bars. These landscape elements support diverse vegetation adapted to flooding, which gradually merges into the surrounding terra firme forest.