Savannas are expansive biomes characterized by a blend of grasslands and scattered trees, forming an open canopy that allows ample sunlight to reach the ground. These ecosystems serve as transitional zones, often situated between dense tropical rainforests and arid desert or grassland regions. South America hosts some of the world’s most biodiverse savannas, representing the continent’s second-largest vegetation type after tropical forests.
Defining Features and Major Regions
South American savannas are defined by a distinct climate featuring alternating wet and dry seasons, supporting a unique vegetation structure. During the wet season, these regions receive substantial rainfall (1200-1800 mm annually), while the dry season, lasting several months, sees significantly less precipitation (as little as 5 mm per month). This seasonality influences soil types, which range from shallow and sandy to deep and clayey. Soils are typically well-drained, reddish or yellowish, and can be nutrient-poor. Vegetation includes a continuous herbaceous layer of grasses, intermingled with shrubs and scattered trees, typically 6-12 meters tall.
Among the prominent savanna regions in South America, the Cerrado in Brazil stands out as the largest, extending into parts of eastern Bolivia and northeastern Paraguay. This vast ecoregion covers approximately 2.9 million square kilometers. The Llanos, located in Venezuela and Colombia, is another significant savanna, characterized by extensive plains and seasonally flooded wetlands. The Gran Sabana in southeastern Venezuela, part of the Guianan savanna ecoregion, is known for its unique landscapes featuring rivers, waterfalls, gorges, and isolated table-top mountains called tepuis.
Unique Plant and Animal Life
Plants in South American savannas have developed specific adaptations to survive the challenging environment, particularly frequent fires and seasonal droughts. Many woody species, like those in the Brazilian Cerrado, exhibit thick, corky bark that protects their internal tissues from fire damage. These plants also possess deep root systems or specialized underground organs like woody rhizomes, allowing them to resprout quickly after a fire. Some trees, such as the baobab, store water in their trunks to endure prolonged dry periods, while grasses can go dormant during droughts and rapidly regrow with the onset of rains.
These savannas are home to a variety of adapted animal species. The giant anteater, a terrestrial insectivorous mammal, uses its powerful foreclaws to dig for ants and termites and its long, sticky tongue to collect its prey. Capybaras, the world’s largest rodents, are semi-aquatic and thrive in the savanna’s waterways and wetlands, often found basking on banks or floating vegetation. The maned wolf, recognizable by its long legs that aid in navigating tall grasses, is an omnivore with a diet that includes fruits and small rodents. Though called “wolves,” they are not true wolves and pose no threat to larger animals like capybaras.
Ecological Role and Conservation
South American savannas provide a range of ecological services, including carbon sequestration and water regulation. These ecosystems store substantial carbon, with 150-200 tons per hectare stored underground in their soils and deep roots. The Cerrado, for instance, acts as the headwaters for three of South America’s largest river basins, playing a role in regulating water flow for human consumption, agriculture, and hydroelectric power.
Despite their ecological significance, these savannas face considerable threats, primarily from agricultural expansion and cattle ranching. Large areas, particularly in the Cerrado, have been cleared for soy and sugarcane cultivation, with half of the biome already converted. This destruction not only releases stored carbon into the atmosphere but also disrupts local rainfall patterns and reduces the capacity of soils and vegetation to regulate water. Conservation efforts are challenged by the small percentage of protected land within these biomes, with less than 3% of the Cerrado under strict protection. Sustainable land management practices and increased awareness are necessary to safeguard these unique and biodiverse ecosystems.