Chaco: Subtropical Floodplain (South America)

Chaco: Subtropical Floodplain (South America)

Wed, 06/26/2019 - 17:49
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The Chaco is a sparsely populated, hot and semi-arid lowland alluvial plain, divided among eastern Bolivia, western Paraguay, northern Argentina and a portion of Brazil. With a high biodiversity, it contains South America's second largest forest.

Chaco: Subtropical Floodplain

The Chaco, also known as Gran Chaco or Dry Chaco, is a sparsely populated, hot and semi-arid lowland alluvial plain (floodplain) of the Río de la Plata basin. It is located in eastern Bolivia, western Paraguay, northern Argentina and a portion of the Brazilian states of Mato Grosso and Mato Grosso do Sul, where it is connected with the Pantanal region.

The region is about 647,500 sq km (250,000 sq mi) in size, though estimates differ. It is located west of the Paraguay River and east of the Andes and is mostly a lowland alluvial sedimentary plain. It is bounded on the west by the Andes mountain ranges and on the east by the Paraguay River and the Paraná River.

The two permanent rivers found in the region, the Pilcomayo and the Bermejo (Teuco), flow southeastward across the plain from their Andean headwaters to the Paraguay River and demarcate the three main regional divisions of the Chaco in Paraguay and Argentina:

  • Chaco Boreal: north of the Pilcomayo
  • Chaco Central: between the two rivers
  • Chaco Austral: south of the Bermejo
Gran Chaco approximate location

Map showing the approximate location of the Gran Chaco region

The region is subject to climates that vary from tropical in the north to warm-temperate in the south. Most of the region, however, is subtropical. Average temperatures vary from 60 to 85 °F (16 to 29 °C), with an average relative humidity between 50 and 75 percent.

More than twice as big as the state of California, the region contains South America’s second-largest forest, behind only the Amazon Rainforest.

Chaco vegetation is adapted to grow under arid conditions and is highly varied and exceedingly complex. From dry thorn forests and cactus stands to palm savannas that flood in the wet season, the region has diverse landscapes and a high biodiversity, containing about:

  • 3,400 species of plants
  • 500 species of birds
  • 150 species of mammals
  • 220 species of reptiles and amphibians

The Gran Chaco is one of South America's last agricultural frontiers. Very sparsely populated and lacking sufficient all-weather roads and basic infrastructure, it has long been too remote for crop planting (the central Chaco's Mennonite colonies are a notable exception).

While advancements in agriculture can bring some improvements in infrastructure and employment for the region, loss of habitat / virgin forest is proving to be substantial.

From 2010 to 2012, for example, Argentina, Paraguay and Bolivia — the three countries that share most of the Chaco — lost native vegetation at an average rate of more than an acre per minute. By 2030, the region is projected to lose millions of additional acres of native vegetation.