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Gran Chaco

The Gran Chaco is a sparsely populated, hot and semi-arid lowland region of the Rio de la Plata basin, divided between eastern Bolivia, 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. This land is sometimes called the Chaco Plain.


The Gran Chaco is about 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.

Historically the Chaco has been divided in three main parts: the Chaco Austral or Southern Chaco, south of the Bermejo River and inside Argentinian territory, blending into the Pampa region in its southernmost end; the Chaco Central or Central Chaco between the Bermejo and the Pilcomayo River to the north, also now in Argentinian territory; and the Chaco Boreal or Northern Chaco, north of the Pilcomayo up to the Brazilian Pantanal, inside Paraguayan territory and sharing some area with Bolivia.

Nowadays locals sometimes divide it simply in regard to the political borders, giving rise to the terms Argentinian Chaco, Paraguayan Chaco and Bolivian Chaco.

The Chaco Boreal may be divided furthermore in two: closer to the mountains in the west, the Alto Chaco, or Upper Chaco, sometimes known as Chaco Seco or Dry Chaco, is very dry and sparsely vegetated, continuing eastward 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 a somewhat swampy plain called the Bajo Chaco or Lower Chaco, sometimes known as Chaco Humedo or Humid Chaco, with 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 with a six-month dry season and sufficient fresh groundwater available only in roughly one third of the region, the remainig aquifers been too salty.

The sandy alluvial soils of the Chaco have very high levels of phosphorus 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" was coined.


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 1870 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. 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. This became the backdrop to The Gran Chaco War (1932-1935) between Paraguay and Bolivia over supposed oil in the Chaco Boreal (the aforementioned region north of the Pilcomayo River and to the west of the Paraguay River). Eventually, Argentine Foreign Minister Carlos Saavedra Lamas mediated a cease fire and subsequent 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 in the region.

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 over nine million people, divided about evenly between Argentina, Bolivia, Brazil, and including around 100,000 in 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, National Routes 16 and 81. All three highways extend about 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

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, or tauga, (Catagonus wagneri), which became known to science 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.C. Michael Hogan. 2008. Guanaco: Lama guanicoe, GlobalTwitcher.com, ed. N. Stromberg

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 Izoceno Guarani, the Ayoreode, and the Chiquitano.

Cattle, crops and deforestation

The Chaco is one of South Americas 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 Chacos Mennonite Colonies are a notable exception.

Two aspects may substantially change Chaco in the near future. Low land valuations

and the region's suitability to grow fuel crops.

Suitability for the cultivation of Jatropha has been proven.

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 Argentinas INTA, so is the Karanday palmtree in the Paraguay Chaco.

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 is substantial. Paraguay, after having lost more than 90% of its Atlantic Rainforest between between 1975 and 2005, is now loosing its xenopheric forest (dry forests) in the Chaco at an anual rate of 220.000 hectare (2008)

Deforestation in the argentinian part of the Chaco amounted to 100.000 hectare per year average between 2001 and 2007

Administrative divisions in the Gran Chaco

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

Tucuman Province, Argentina

Beni Department, Bolivia

Chuquisaca Department, Bolivia

Santa Cruz Department, Bolivia

Tarija Department, Bolivia

State of Mato Grosso do Sul, Brazil

Alto Paraguay Department, Paraguay

Boqueron Department, Paraguay

Presidente Hayes Department, Paraguay

Indigenous peoples of the Gran Chaco

Abipon - no longer exist










Ava Guarani

Simba Guarani








Pai Tavytera








See also

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

External links

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

The website La Plata Basin - Gran Chaco seeks to enhance the complementarity between institutional capacities and ongoing projects in the region so as to strengthen synergies, develop replicable and scalable initiatives, and improve participatory management with communities from the perspective of sustainability and equity.

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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article Gran Chaco

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