Grasslands are biomes covering much of Earth’s land. These ecosystems, characterized by their dominant grass vegetation, support diverse life forms and maintaining ecological processes. They are distributed across various climates and continents, providing a range of environmental benefits. Understanding these vast landscapes is important for appreciating their contributions to global biodiversity and the planet’s overall health.
Understanding Global Grassland Coverage
The percentage of land covered by grasslands worldwide varies depending on how grasslands are defined. Estimates range broadly from approximately 20% to over 50% of Earth’s terrestrial surface. Some classifications, including natural and semi-natural grasslands, indicate coverage between 31% and 69% of the Earth’s land area, excluding Antarctica. Other analyses, including rangelands, suggest that these areas, encompassing grass, shrubs, or sparse vegetation, cover about 54% of the world’s land surface.
Differences in these figures often stem from whether managed pastures and agricultural fodder crops are included alongside natural or semi-natural grasslands. The Food and Agriculture Organization (FAO) data estimated that “Pasture and Fodder Crops” covered about 26% of the world’s land area in 2000. A grassland is defined as an area where vegetation is dominated by grasses, with few or no trees. This definition can encompass various types, from pristine natural areas to those influenced by human activities such as grazing or mowing.
The Vital Ecological Role of Grasslands
Grasslands perform several functions that are important for planetary health. They act as carbon sinks, storing large amounts of carbon, primarily within their extensive root systems and the soil. Unlike forests, which store much of their carbon above ground, grasslands sequester approximately 90% of their carbon below the surface, making them resilient carbon reservoirs, especially against disturbances like wildfires. This underground carbon storage helps stabilize soils and contributes to climate regulation.
These biomes support a wide array of biodiversity, providing habitat for numerous plant and animal species. Grasslands are home to diverse plant communities, including grasses, sedges, and various herbs, and can support a rich invertebrate fauna. They also provide sustenance for large grazing mammals and smaller organisms, playing a role in food chains and nutrient cycling. Beyond carbon and biodiversity, grasslands contribute to soil health by preventing erosion through their dense root networks, which bind soil particles and enhance water infiltration. This helps maintain soil fertility and reduces runoff, improving water quality in local watersheds.
Geographical Distribution and Diverse Forms
Grasslands are found across nearly all continents, occurring in both tropical and temperate regions from sea level to high mountain elevations. Examples include the North American Prairies, known for their tallgrass and shortgrass varieties depending on rainfall. In Africa, the Savannas feature grasses interspersed with scattered trees like acacias. Eurasia hosts the extensive Steppes, stretching from Eastern Europe to Mongolia.
South America features the Pampas in Argentina, Uruguay, and Brazil, along with the Llanos in Venezuela and Colombia. Other forms include montane grasslands found in high-altitude regions like the Tibetan Plateau, and flooded grasslands such as the Pantanal in Brazil. Desert grasslands also exist on the fringes of arid regions, with vegetation adapted to limited moisture. These diverse forms illustrate how grasslands adapt to a range of climatic conditions, from hot, wet-dry tropics to cold, temperate zones with distinct seasons.