Grassland Biome
Grasslands are the biome that feeds the world. Covering a quarter of Earth's land surface and found on every continent except Antarctica, they are the most widespread terrestrial ecosystem on the planet. Their deep, fertile soils underlie the wheat fields of Ukraine, the corn belt of the American Midwest, the cattle ranches of Argentina, and the breadbaskets of every civilisation that has ever existed. Grasslands also support the greatest concentrations of large grazing mammals on Earth — from the million-strong wildebeest herds of East Africa to the bison that once darkened the North American plains.
- Area Coveredapprox. 25% of landMore than any other terrestrial biome
- LocationEvery continentExcept Antarctica — prairies, steppes, pampas, veldt
- Annual Rainfall250–750 mmEnough for grass, not enough for forest
- Temperature−40°C to 38°CTemperate grasslands have extreme seasonal swings
- Soil DepthUp to 6 metresDeep, fertile soils built over thousands of years
- Original Cover70% lostConverted to farmland — the most altered biome on Earth
How does grassland rainfall compare to other biomes?
Grasslands sit in the rainfall gap between desert and forest — enough water for grass, not enough for trees.
Rainfall is the single biggest factor determining whether a region becomes grassland, forest or desert. In the interior of continents — far from the moisture of the ocean — rainfall settles into the 250–750 mm range that grass can exploit but trees struggle with. Add periodic drought and fire, and grassland becomes stable for thousands of years.
What is the Grassland Biome?
A grassland is a biome where the natural vegetation is dominated by grasses rather than trees or shrubs, forming vast open landscapes that stretch to the horizon in every direction. Grasslands develop where rainfall is enough to support plant growth — typically 250–750 mm per year — but not enough or reliably enough for trees to establish and dominate. Three forces keep grasslands as grasslands: climate (insufficient or unreliable rain), fire (which kills tree seedlings but merely scorches the roots of grasses, which regrow immediately), and grazing (large herbivores eat and trample tree seedlings before they can establish).
Grasslands go by many names around the world, each reflecting local character: prairie in North America (from the French for meadow), steppe across Central Asia and Eastern Europe (from Russian, meaning flat grassy plain), pampas in South America (from Quechua, meaning flat surface), veldt in southern Africa (from Afrikaans, meaning open country), and rangelands in Australia. Despite the different names, all share the same essential character — vast skies, waving grass and an openness found in no other biome.
Where are Grasslands found?
The great grassland regions of the world cluster in the interiors of continents, far from the ocean's moderating and moistening influence. North America's Great Plains and central prairies once covered approx. 3 million square kilometres from the Rocky Mountains to the Mississippi River and from southern Canada to Texas. The Eurasian steppe runs for 8,000 kilometres from Hungary through Russia, Kazakhstan, Mongolia and into China — the longest continuous grassland on Earth. Sub-Saharan Africa's savannas and grasslands span a wide band south of the Sahara. South America's pampas cover much of Argentina, Uruguay and southern Brazil. Australia's interior rangelands and Mitchell grass plains stretch across Queensland and the Northern Territory. In total, grasslands once covered roughly 25% of Earth's land — though up to 70% of that original cover has since been converted to agriculture.
Climate and fire
The grassland climate is defined by contrast and unpredictability. Temperate grasslands such as the North American prairie and the Eurasian steppe experience some of the most extreme seasonal temperature swings on Earth — summer highs of 38°C and winter lows of −40°C in a single year. Rainfall is not just low (250–750 mm) but unreliable, with droughts striking every few years in most grassland regions. This unpredictability is actually part of what maintains grasslands — trees need reliable water to establish, but grasses can survive drought by going dormant and waiting.
Fire sweeps through grasslands at regular intervals, ignited by lightning or — historically — by people. A grassland fire can move faster than a human can run, burning off the standing dry grass within minutes. For the grasses, this is barely an inconvenience: their growing points are underground, protected from the heat, and within days of a fire the landscape is carpeted with vivid green new growth. Tree seedlings, by contrast, are killed by fire. This is why grasslands that would otherwise succeed to woodland remain open: fire resets the clock each time trees begin to gain a foothold.
Plants of the Grassland
Grasses are the dominant plants of this biome — and they are among the most evolutionary successful plant families on Earth, with approx. 10,000 species found worldwide. Grassland grasses have evolved two key features that make them almost indestructible: deep, extensive root systems that can reach 3–6 metres into the soil (storing energy for regrowth after fire or drought), and the ability to photosynthesise from the base of the leaf rather than the tip — meaning that even after grazing or burning removes the visible green tissue, the leaf simply grows back from below. In the tallgrass prairie of North America, big bluestem grass can reach 3 metres tall in a good year. In the shortgrass plains, blue grama and buffalo grass form a dense, low turf. Between the grasses grow wildflowers (forbs) including sunflowers, clovers, coneflowers and prairie lilies, adding colour and providing nectar for insects.
Animals of the Grassland
Grasslands support some of the most spectacular concentrations of large mammals on Earth. In Africa, wildebeest, zebra, buffalo, Thomson's gazelle and impala graze the open plains in vast herds, driven in seasonal migrations by the rains. Lions, cheetahs, leopards, wild dogs and hyenas pursue them. In North America, pronghorn antelope — the second-fastest land animal after the cheetah — sprint across the remaining prairies, while coyotes, badgers, prairie rattlesnakes and burrowing owls inhabit a landscape that once teemed with bison and wolf. The Mongolian steppe still supports Przewalski's horses (the only truly wild horses in existence), saiga antelope, and the Pallas's cat. Underground, grasslands are rich in burrowing rodents — prairie dogs, ground squirrels, gophers, hamsters and voles — that are keystone species: their burrows provide homes for dozens of other species and their grazing keeps the grass structure open.
Grassland food web
The grassland food web begins with an extraordinarily productive base layer of grasses, wildflowers and other plants. Primary herbivores are the most diverse and numerous of any biome: in African grasslands, zebra, wildebeest, buffalo, impala, gazelle, hartebeest and many other antelope species all graze the same area but on different grasses, different parts of grasses, or at different heights — an ecological partitioning that allows many species to coexist. In North American prairies, bison, pronghorn, prairie dogs, ground squirrels, jackrabbits and grasshoppers fill the same herbivore roles. Insects — grasshoppers, beetles and caterpillars — consume enormous quantities of plant material and are in turn a critical food source for birds, lizards and small mammals. Primary carnivores — coyotes, jackals, foxes, hawks and eagles — hunt the smaller herbivores. Apex predators including lions, cheetahs, leopards, wild dogs and hyenas (in Africa) or wolves (in North America and Central Asia) hunt the large herbivores. Vultures, marabou storks and other scavengers process the remains. Underground, dung beetles bury animal droppings, recycling nutrients directly back into the soil. Decomposers — earthworms, bacteria and fungi — process dead material through the extraordinarily deep, rich grassland soils.
How animals adapt to the Grassland
Grassland animals have evolved adaptations to the open landscape, seasonal drought and fire. Speed and endurance are paramount for prey species with nowhere to hide: the pronghorn antelope of North America can sustain 88 km/h — the second fastest land animal — and run at 56 km/h for long distances, an adaptation to the open prairie where escape from predators requires outrunning them over distance. The cheetah uses explosive short-distance sprints (up to 120 km/h) to catch gazelles. Many grassland herbivores have wide-set eyes giving near-360° vision to detect predators approaching across the open plain. Burrowing is another key adaptation: prairie dogs, ground squirrels, meerkats, wombats and many other grassland animals dig tunnel systems that provide shelter from both temperature extremes and predators, and survive fire by retreating underground. Migratory behaviour is perhaps the most spectacular grassland adaptation — wildebeest, caribou, bison and saiga antelope all travel hundreds or thousands of kilometres to follow seasonal grass growth, avoiding areas that are overgrazed or dried out. Birds such as larks and pipits nest on the ground, relying on cryptic colouring rather than tree cover for protection. Some grassland species, like the African ground squirrel, use their own bushy tail as a parasol, holding it over their back to shade themselves from the sun.
Threats and conservation
Grasslands are the most heavily converted biome on Earth. Because their deep, fertile soils are so productive for agriculture, the world's great grasslands have been ploughed up at a staggering rate. Less than 4% of North America's original tall-grass prairie survives intact. Ukraine's steppes — once among the most biodiverse grasslands in the world — are now almost entirely farmland. The South American pampas has been converted to vast soya bean and cattle farming operations. This conversion doesn't just destroy biodiversity — it releases enormous amounts of carbon stored in the deep soil, contributes to soil erosion, and reduces the natural flood regulation that healthy grasslands provide. Overgrazing by livestock degrades remaining grasslands by compacting soil, reducing plant diversity and triggering desertification. Climate change is shifting rainfall patterns and extending droughts in many grassland regions.
Deeper dive: grassland soils — the world's most valuable agricultural resource
The secret of the grassland is underground. Centuries of grass growth — roots decaying, earthworms processing, bacteria cycling nutrients — have built some of the deepest, most fertile soils on Earth. Prairie topsoil can be up to 6 metres deep, compared to just 15–30 cm in tropical forest soils. The dark colour comes from humus — decomposed organic matter — and a single cubic metre of healthy prairie soil can contain more than 2 billion earthworms, bacteria, fungi and other organisms. This is the soil that built the breadbaskets of the world: the US Midwest grows more than a third of the world's maize and soya on converted prairie; Ukraine and Russia's black earth (chernozem) steppes produce much of the world's wheat. But ploughing exposes this stored carbon to the air, releasing it as CO₂. Industrial farming also compacts and erodes soil, reducing its depth by millimetres each year — a process that took thousands of years to build cannot be replaced on a human timescale.
The concept of "prairie restoration" aims to return converted farmland to native grassland, rebuilding soil, sequestering carbon, restoring biodiversity and reducing flood risk. Projects across the US Great Plains, European steppes and South African veldt are showing that even severely degraded grassland can begin recovering within a decade if grazing pressure is managed and native seed mixes are planted.
Grasslands are where the world's food comes from — and where some of its most spectacular wildlife survives. The closely related Savanna Biome is a warmer, tropical version of the grassland story, where scattered trees share the landscape with the grass.