The Llanos, meaning “The Plains” in Spanish, are a vast tropical grassland ecoregion. This expansive savanna stretches across South America, characterized by flat terrain and extensive grasslands.
Geographic Setting and Climate
The Llanos are primarily located in northwestern South America, extending across parts of Colombia and Venezuela, situated to the east of the Andes Mountains. This lowland area covers approximately 220,000 to 260,000 square miles (570,000 to 670,000 square kilometers) and is bounded by the Venezuelan Coastal Range to the north, the Guiana Highlands to the southeast, and the Amazon River basin to the south.
The region experiences a tropical savanna climate, marked by pronounced wet and dry seasons. The rainy season occurs from April to November, with heaviest rainfall in June and July. The dry season runs from December to March, bringing warmer temperatures and lighter breezes. This annual cycle of heavy rainfall followed by drought dictates the landscape, leading to widespread flooding during the wet season that transforms the grasslands into temporary wetlands, with waters receding during the dry period.
Biodiversity of the Llanos
The Llanos boast a rich variety of life, adapting to the dramatic seasonal changes. The vegetation includes vast open grasslands, savannas with scattered trees, and gallery forests that grow along rivers and streams. These distinct plant communities include “llano bajo” or low plains, which flood seasonally, and “llano alto” or high plains, which remain drier with grasses and shrubs 30–100 cm high.
The diverse fauna of the Llanos includes iconic animals such as the capybara, the world’s largest rodent, seen grazing in the grasslands. The region is also home to predators like the green anaconda, one of the world’s largest snakes, and spectacled caimans, which congregate around shrinking water sources during the dry season. Bird species are abundant, with approximately 475 recorded, including migratory birds that gather in large numbers during the dry season, such as scarlet ibises and jabirus. Other notable species include giant anteaters, various deer species, armadillos, tapirs, and rare pink river dolphins in the larger river systems.
Ecological Importance
The Llanos play a role in regional hydrology, acting as a natural system for water management. During the wet season, the vast plains absorb large volumes of rainfall, transforming into expansive wetlands that store water. This stored water is then slowly released into major river systems, such as the Orinoco and its tributaries, throughout the dry season, influencing water availability across a broad geographical area.
Beyond water regulation, the Llanos also contribute to the global carbon cycle as a carbon sink. Terrestrial ecosystems, including grasslands, absorb carbon dioxide from the atmosphere, helping to moderate climate change. The rich plant life and soils of the Llanos store considerable amounts of carbon, contributing to global biodiversity and the planet’s ecological balance.
Conservation Challenges
The Llanos grasslands face numerous threats. Agricultural expansion, particularly cattle ranching and crop cultivation like rice, corn, and palm oil, leads to habitat loss and fragmentation. This conversion of natural grasslands into pastures and farmlands reduces the area available for native flora and fauna.
Oil and gas exploration and extraction activities also cause disturbances across the region. These operations can lead to habitat destruction, pollution, and further fragmentation of the landscape. The impacts of climate change, such as altered rainfall patterns and increased frequency of human-induced fires, also threaten the delicate balance of the wet and dry seasons, affecting plant compositions and wildlife habitats. Addressing these challenges through sustainable practices helps protect this South American savanna.