A hot, dry plain of around 100 million ha, the Gran Chaco comprises a range of habitats from dry thorn forests and cactus stands to palm savannahs that are flooded in the wet season. The Gran Chaco has high levels of biodiversity, containing around 3,400 plant species, 500 birds, 150 mammals and 220 reptiles and amphibians. Its central location in South America makes it an important refuge for many migrating birds.
The Chaco has been gradually converted over long periods, but the rate of conversion of natural vegetation has accelerated in recent years. Around 12 to 15% of the natural Chaco landscape has been converted into agricultural uses.
In Argentina, some 1.2-1.4 million ha (85% of the national deforestation total) was cleared in 30 years, a deforestation rate of 2.2% per year. As controls have tightened on felling Atlantic Forest remnants, particularly in Paraguay, pressure has mounted on the neighbouring Gran Chaco. From 2010 to 2012, for example, a total of 823,868 ha was cleared in the three main countries, three-quarters in Paraguay.
In Bolivia, the heart of Gran Chaco is protected by the Kaa-Iya del Gran Chaco National Park and indigenous area. But land to the north and west, where the soil is extremely fertile, is being cleared for agriculture.
The Soy Factor
Agricultural expansion, largely driven by soy, is the biggest threat to the natural ecosystems of the Gran Chaco. In Argentina, agricultural expansion, and soy cultivation in particular, is the main cause of deforestation. Growing market demand, coupled with innovations such as GM, zero-tillage and other technological changes, have made cultivation in drier and less productive areas more viable.
Before 2004, Paraguay had the second-highest deforestation rate in the world but since the government legislated the 2004 Forest Conversion Moratorium, in order to protect the Atlantic Forest in Paraguay, soy in the region has increasingly been grown on land previously used to raise cattle. As the law pertains only to the protection of forest and not to other landscapes such as savannahs, an unexpected result has been that cattle ranching has expanded massively into the Gran Chaco.
Some soy is also now being cultivated directly in the Paraguayan Chaco. Pressure on the Gran Chaco seems set to continue to increase, with infrastructure in the region developing rapidly.
Argentina’s paved road network has increased by 10% in the last 7 years, while the Initiative for the Integration of the Regional Infrastructure of South America (IIRSA) plans to link the Chaco with Pacific ports in Chile, opening up better links to Asian markets; as part of this, reconstruction of the Belgrano cargo railway in Argentina is already under way.
In Bolivia, intensive agriculture has been limited historically by the semi-arid climate, but this is changing as farmers adopt irrigation technology.