South America is home to expansive grasslands, a significant biome characterized by dominant herbaceous vegetation. Spanning millions of square kilometers, these grasslands are not uniform, encompassing a variety of landscapes from humid plains to semi-arid savannas. They represent a substantial portion of the continent’s landmass, supporting diverse life forms.
Characteristics of South American Grasslands
South American grasslands are defined by distinct physical and environmental characteristics. Climate patterns generally involve seasonal rainfall and temperature fluctuations. For instance, the Campos region experiences a subtropical climate with warm summers and winter frosts, often with a moisture surplus in autumn and spring but moderate deficits in summer. Annual precipitation in areas like the Pampas ranges from 600 to 1,200 mm, distributed relatively evenly throughout the year.
The dominant vegetation consists primarily of grasses and herbaceous species, with a notable absence of dense tree cover. Trees and shrubs are scarce, found near water sources or in specific savanna types. Soil types vary, but many natural grasslands historically developed under low fertility. Despite this, regions like the Humid Pampas are known for deep, nutrient-rich loess soils, highly suitable for agriculture. Grasslands can include both C3 and C4 grass species, reflecting adaptations to different climatic conditions.
Key Grassland Regions and Their Locations
South America features several major grassland regions, each with unique geographical characteristics.
The Pampas, meaning “plain” in Quechua, are fertile lowlands covering over 1,200,000 square kilometers. This region primarily spans Argentine provinces like Buenos Aires and extends into Uruguay and Brazil’s Rio Grande do Sul. The Pampas divide into Humid Pampas, with fertile soil and high rainfall, and Dry Pampas, with an arid climate and lower rainfall.
To the north, the Llanos are extensive grasslands in western Venezuela and northeastern Colombia, covering approximately 570,000 square kilometers. This tropical plain is bordered by the Andes Mountains and the Orinoco River basin. The Llanos have subtle topographic variations, with elevations rarely exceeding 300 meters, leading to extensive seasonal flooding.
The Cerrado, a vast tropical savanna ecoregion, is primarily in central Brazil. It is the second-largest biome in South America, encompassing about 2,036,448 square kilometers (22% of Brazil’s territory), and extends into Paraguay and Bolivia. This region is recognized for its diverse habitats, from grasslands to dry forests.
Further south, the Gran Chaco is a vast, semi-arid lowland covering over 647,500 square kilometers across eastern Bolivia, western Paraguay, northern Argentina, and parts of Brazil. The name “Chaco” comes from the Quechua word “chaqu,” meaning “hunting land.” This alluvial plain is located west of the Paraguay River and east of the Andes, with its largest portion in Argentina.
Life Within the Grasslands
South American grasslands support a wide array of plant and animal life, many exhibiting specific adaptations. Plant adaptations often include mechanisms for drought resistance and fire adaptation. For example, some plants in the drier Pampas have adapted to windy conditions, and the Ombu tree has a fire-resistant trunk due to its high water content. Grasses like Paspalum notatum, Sporobolus indicus, and Axonopus argentinus are common in the Campos, while Stipa, Piptochaetium, Paspalum, and Panicum are characteristic in the Pampas.
The fauna includes iconic species suited to open habitats. The Greater Rhea, a large flightless bird similar to an ostrich, uses its long legs for an elevated view and reaches speeds over 50 kilometers per hour to escape danger. Mammals like the capybara, the world’s largest rodent, inhabit the Llanos, often nesting in gallery forests and feeding on grassland vegetation. Giant anteaters are also present, known for ripping open termite mounds.
Armadillos are abundant and widespread, with some species able to roll into defensive balls. Various deer species, such as the Pampas deer, and predators like the maned wolf and puma, also reside here. Many grassland animals have developed adaptations like running quickly, efficient grazing, or burrowing underground for protection from harsh conditions and predators.
Environmental Importance and Human Connection
South American grasslands are important ecologically, supporting rich biodiversity. They play a role in carbon sequestration, with studies suggesting that introduced deep-rooted grasses can store substantial organic carbon deep in the soil. While some research indicates Pampas grasslands might not actively sequester carbon, overall, grasslands contribute to soil organic carbon storage. These biomes also contribute to water regulation, particularly regions like the Cerrado, considered a “water fountain” for major South American river basins like the Amazon, Paraná-Paraguay, and São Francisco.
They are biodiversity hotspots, housing numerous species of plants, birds, and mammals. The Cerrado, for instance, is the most biodiverse savanna globally, with thousands of native plant species, many endemic. However, human activities have impacted these landscapes. Traditional uses include extensive ranching and agriculture, particularly in fertile regions like the Pampas, which are major grain-growing areas.
Large-scale agriculture, such as soy and cattle farming, has led to significant land conversion and deforestation, especially in the Cerrado and Gran Chaco. Nearly half of South American temperate grasslands have been converted or degraded, with only a small percentage included in protected areas. This highlights the ongoing human interaction, where economic activities exert considerable pressure on these valuable ecosystems.