Gran Chaco

Landscape in the Gran Chaco, Paraguay.

The Gran Chaco (Quechua chaku, "hunting land") is a sparsely populated, hot and semi-arid lowland region of the Río de la Plata basin, divided between eastern Bolivia, Paraguay, northern Argentina and a portion of the Brazilian state of Mato Grosso. This land is sometimes called the Chaco Plain.

Geography

Very approximate location and borders of the Gran Chaco. The natural border to the west is the Andes and, to the east, the Paraguay River. Northern and southern borders are a bit less well-defined. (Underlying map taken from the CIA World Factbook)

global soil types according USDA soil taxonomy, Mollisol shown bright green, a soil type which the Chaco shares with the world's major grain producing areas – click to enlarge

Chaco Boreal, virgin forest in dry season

Bajo Chaco, extensive cattle ranching

The Gran Chaco is about 647,500 km² (250,001 sq mi) in size, though estimates differ. It is located west of the Paraguay River and east of the Andes, mostly an alluvial sedimentary plain shared among Paraguay, Bolivia and Argentina. It stretches from about 17° to 33° South latitude and between 65° and 60° West longitude, though estimates differ in this case too. Closer to the mountains in the west, the Alto Chaco, or Dry Chaco, is very dry and sparsely vegetated, continuing eastward to the Chaco Boreal, where less arid conditions combined with favorable soil characteristics permit a seasonally dry higher growth thorn tree forest, and further east again where still higher rainfall combined with improperly drained lowland soils lead to the Bajo Chaco, or Humid Chaco, a more open savanna vegetation consisting of palm trees, quebracho trees and tropical high grass areas with a wealth of insects. The landscape is mostly flat and slopes at a 0.004 degree gradient to the east. This area is also one of the distinct physiographic provinces of the Parana-Paraguay Plain division.

The areas more hospitable to development are along the Paraguay, Bermejo and Pilcomayo Rivers. It is a great source of timber and tannin, which is derived from the native quebracho tree. Special tannin factories have been constructed there. The wood of the palo santo from the Central Chaco is the source of oil of guaiac (a fragrance for soap). Paraguay also cultivated mate in the lower part of Chaco.

The Chaco offers high soil fertility and a topography that is favorable for agricultural development, but in combination with aspects that are challenging for farming: A semi-arid to semi-humid climate (600–1300 mm annual rainfall) with a six-month dry season and sufficient sweet groundwater available only in roughly one third of the region.

The sandy alluvial soils of the Chaco have very high levels of phosphorus ^[1] and other nutrients, an aspect that may gain more attention at a time when the prices of phosphate and phosphate-based fertilisers have multiplied by 2008 and even the term "peak phosphorus" coined.

History

The Gran Chaco had been a disputed territory since 1810. Officially, it was supposed to be part of Argentina, Bolivia and Paraguay, although a bigger land portion west of the Paraguay River had belonged to Paraguay since its independence. Argentina claimed territories south of the Bermejo River until Paraguay's defeat in the War of the Triple Alliance in 1871 established its current border with Argentina. Over the next few decades, Bolivia began to push the natives out and settle in the Gran Chaco while Paraguay ignored it. It was the scene of The Gran Chaco War (1932-1935) (though violence started as early as December 5, 1928) between Paraguay and Bolivia over supposed oil in Chaco Boreal (a region north of the Pilcomayo River and to the west of the Paraguay River). Bolivia sought the Paraguay River for shipping oil out into the sea (it had become a land-locked country after the loss of its Pacific coast in the War of the Pacific) and Paraguay claimed ownership of the land. Eventually, Argentine Foreign Minister Carlos Saavedra Lamas mediated a treaty signed in 1938, which gave Paraguay three quarters of the Chaco Boreal and gave Bolivia a corridor to the Paraguay River with the ability to use the Puerto Casado and the right to construct their own port. In the end, oil was not found there.

Road construction in the deep Gran Chaco during the 1960s

Mennonites came into the Paraguayan part of the region from Canada in the 1920s; more came from the USSR in the 1930s and immediately following World War II. These immigrants created some of the largest and most prosperous municipalities in the deep Gran Chaco.

The region is home to around ten million people, divided about evenly between Argentina, Bolivia, Brazil and Paraguay. The area remains relatively underdeveloped, however; to help address this, in the 1960s the Paraguayan authorities had the Trans-Chaco Highway built and the Argentine National Highway Directorate Route 16 and Route 81. All three highways extend about 700 km (450 mi) from east to west and are now completely paved, as are a network of nine Brazilian highways in Mato Grosso do Sul State.

Flora and fauna

An Algarrobo in the Gran Chaco area of Argentina. This prized shade tree is common to the area.

The Gran Chaco has some of the highest temperatures on the continent.

The ecosystems of the Gran Chaco are unique and were little understood by scientists until recent years. These ecosystems are slowly being destroyed by civilization with the introduction of cattle, burning of vegetation and irresponsible agricultural decisions. Many groups are trying to protect this unique set of ecosystems.

The Chacoan Peccary (Catagonus wagneri), which was discovered in the 1970s, is a large mammal endemic to Chaco. The Chaco is a center of armadillo diversity, with at least eight species in the Argentine Chaco and ten species in the Paraguayan Chaco. Guanaco were present in large numbers prehistorically but now occur in diminished numbers.^[2]

In September 1995, the Kaa Iya del Gran Chaco National Park was established in an area of Chaco in Bolivia. It is administered and was established solely by the indigenous peoples, including the Izoceño Guaraní, the Ayoreode, and the Chiquitano.

The Chaco and fuel crops

Sorghum harvest 2008, Linea 14, Agua Dulce Region, Alto Paraguay

The Chaco is one of South America’s last agricultural frontiers. Very sparsely populated and lacking sufficient all-weather roads and basic infrastructure (the Argentinian part is more developed than the Paraguayan or Bolivian part), it has long been too remote for crop planting. The central Chaco’s Mennonite Colonies are a notable exception.

Two aspects may substantially change Chaco in the near future. Low land valuations ^{[3] [4]} and the region's suitability to grow fuel crops. Suitability for the cultivation of Jatropha has been proven. ^{[5] [6]}, Sweet sorghum as an ethanol plant may prove viable, too, since sorghum is a traditional local crop for domestic and feedstock use. Switchgrass / The feasibility of Pasto Varilla is currently being studied by Argentina’s INTA ^[7], so is the Karanda’y palmtree in the Paraguay Chaco ^[8].

While advancements in agriculture will bring some improvements in infrastructure and employment for this traditionally rather neglected and impoverished region, loss of habitat / virgin forest could be substantial.

Administrative divisions in the Gran Chaco

Sturdy brangus cattle in western Paraguay; cattle ranching takes up most of the area's useful land.

Hydroelectric dam on the Río Negro, near Resistencia, Chaco (Argentina); the torrential rains that follow the region's long dry season make flood-control works critical.

Toba family, Formosa Province, 1892.

A jaguar at rest in the Formosa Province Wildlife Rehabilitation Center.

The following Argentine provinces, Bolivian and Paraguayan departments and Brazilian states lie in the Gran Chaco area, either entirely or in part:

• Chaco Province, Argentina
• Formosa Province, Argentina
• Salta Province, Argentina
• Santa Fe Province, Argentina
• Santiago del Estero Province, Argentina
• Tucumán Province, Argentina
• Beni Department, Bolivia
• Chuquisaca Department, Bolivia
• Santa Cruz Department, Bolivia
• Tarija Department, Bolivia
• Mato Grosso do Sul State, Brazil
• Alto Paraguay Department, Paraguay
• Boquerón Department, Paraguay
• Presidente Hayes Department, Paraguay

Indigenous peoples of the Gran Chaco

• Abipón - no longer exist
• Ayoreo
• Chamacoco
• Chané
• Chiquitano
• Chiripá
• Chorote
• Enxet
• Enlhet
• Guana
• Ava Guaraní
• Simba Guaraní
• Guarayo
• Kaiwá
• Maká
• Maskoy
• Mbyá
• Mocoví
• Nivaclé
• Pai Tavytera
• Pilagá
• Pucú
• Sanapaná
• Tapieté
• Toba
• Wichí
• Yuqui

See also

• Kaa-Iya del Gran Chaco National Park and Integrated Management Natural Area

References

External links

Wikimedia Commons has media related to: Gran Chaco

• The National Museum of Natural History's description of Gran Chaco
• Chaco ecoregion (World Wildlife Fund)
• Humid Chaco ecoregion (World Wildlife Fund)
• Food and Agriculture Organization of the United Nations' description of the Gran Chaco - focuses mainly on agriculture.
• Some stamps showing the dispute over the Gran Chaco before the war - some people claim this was the spark that ignited the war
• photos of the Paraguay Chaco

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