A grassland biome is characterized by vast, open, non-forested areas dominated by grasses and other herbaceous plants. These biomes cover roughly a quarter of the Earth’s land surface, existing as transitional zones between forests and deserts. These expansive ecosystems support a unique array of wildlife and have historically been important for human civilization. Understanding the global distribution of these biomes involves examining the specific countries and regions where these distinct grassy landscapes have developed.
Temperate Grasslands of North America and Eurasia
The largest stretches of temperate grasslands occur in the mid-latitudes, far from the moderating influence of oceans, leading to hot summers and cold winters. North America’s primary grassland is the Great Plains, which sweeps across the central portion of the continent. This area encompasses a significant portion of the United States, covering states like Kansas, Nebraska, the Dakotas, Montana, Wyoming, Oklahoma, and Texas.
The northern extension of this biome reaches into Canada, where it is known as the Prairies, covering the southern portions of Alberta, Saskatchewan, and Manitoba. The region is characterized by a gradual change in grass height, transitioning from taller grasses in the humid east to shorter varieties in the drier west. The deep, fertile soils here have made this area a major agricultural region for both countries.
Across the globe, the Eurasian Steppe forms the other massive temperate grassland, stretching for approximately 5,000 miles from Eastern Europe to East Asia. This continental biome includes a large portion of Russia, particularly the southern areas near the Black and Caspian Seas, and extends through Ukraine. Further east, the Steppe covers the vast territory of Kazakhstan.
The biome continues into Central Asia and the Far East, covering much of Mongolia and extending into the northern regions of China, specifically Inner Mongolia. Smaller pockets of the Eurasian Steppe are found in Eastern European countries like Romania, Moldova, and Hungary. These temperate zones are largely treeless plains, shaped by a continental climate and a history of grazing by large herds of animals.
Tropical Savannas of Africa and Australia
Tropical grasslands, commonly known as savannas, are located closer to the equator and are characterized by high temperatures with distinct wet and dry seasons, often featuring scattered trees. The African Savanna covers nearly half of the continent. This massive biome spans a multitude of nations, including East African countries such as Tanzania and Kenya, home to the Serengeti ecosystem.
Further south, the savanna transitions into the Veld, concentrated primarily in South Africa, but also extending into neighboring countries like Botswana, Zimbabwe, and Namibia. The presence of scattered, drought-resistant trees, such as acacias and baobabs, distinguishes these savannas from temperate grasslands. Other countries with large savanna regions include Uganda, Sudan, Ethiopia, and the Democratic Republic of the Congo.
The other major region for tropical grasslands is Australia, where the biome is broadly referred to as the Rangelands or tropical savannas. These ecosystems stretch across the northern third of the continent, encompassing vast areas of the Northern Territory and Queensland. This region is dominated by eucalypt savannas and native grasslands.
The Australian tropical savannas are defined by a strong monsoonal climate, creating a cycle of intense wet seasons followed by prolonged dry periods. This seasonal pattern, along with the prevalence of fire, helps maintain the grassy understory and prevents the establishment of dense forest cover. The Rangelands are home to a unique biodiversity adapted to the arid and semi-arid conditions of the Australian interior.
South American Grassland Biomes
South America contains two major grassland systems that differ from the African and Eurasian models. The Pampas is a fertile temperate grassland dominating the southeastern part of the continent. This productive biome is primarily located in Argentina, covering a large central area extending from the Atlantic coast toward the Andes Mountains.
The Pampas also extends eastward, covering the entire country of Uruguay and reaching into the southernmost state of Brazil, Rio Grande do Sul. This region benefits from a temperate climate with precipitation that is distributed relatively evenly throughout the year, supporting the deep, rich soils ideal for agriculture and cattle ranching.
To the north, the Llanos represent a vast tropical grassland found in the Orinoco River basin. This biome is shared between two northern South American countries: Venezuela and Colombia. The Llanos are characterized by a dramatic seasonal cycle involving extensive flooding during the wet season, followed by severe drought during the dry season.
The region’s landscape is generally low-lying, with elevations rarely exceeding 1,000 feet. This constant environmental fluctuation maintains the grassland ecosystem, supporting wildlife adapted to these extreme conditions. The Llanos biome is shaped by hydrological cycles rather than purely aridity.
Ecological Factors Determining Global Distribution
The geographic location of major grassland biomes is primarily controlled by two climatic factors: precipitation and temperature. Grasslands exist in regions that receive too little annual rainfall to support continuous forest growth, but enough moisture to prevent the formation of a true desert. This results in a semi-arid climate where water is a limiting factor for plant growth for at least part of the year.
The concentration of these biomes in the interior of continents, known as continentality, contributes to limited moisture. Being far from oceanic moisture sources, these areas experience low rainfall and greater temperature extremes, which restricts tree growth. These conditions favor the growth form of grasses, which allocate a large proportion of their biomass below ground in roots and rhizomes.
Secondary factors that maintain these expansive grasslands include fire and grazing pressure. Periodic fires, often ignited naturally, prevent the encroachment of woody shrubs and trees by burning accumulated dry plant material. Similarly, the long history of grazing by large herbivores, such as bison or wildebeest, has shaped the resilience of grasses and kept the landscape open.