Grassland Biomes

Grasslands are biomes dominated by grasses and other low-growing plants, with few or no trees. They develop in regions where rainfall is too low and irregular to support dense forest but high enough to prevent the land from becoming desert. Periodic fires, grazing by large animals and seasonal drought all help keep grasses dominant by suppressing the growth of trees and shrubs. Grasslands occur on most continents and are known by many regional names.

Ecologists often distinguish two broad kinds. Temperate grasslands, such as the steppe of Eurasia and the prairies of North America, occur in mid-latitudes with cold winters and warm summers. Tropical grasslands, such as the savanna, occur in warmer regions and typically have a pronounced wet and dry season, sometimes dotted with scattered trees. Both types are shaped by their climate and by the cycle of growth and dormancy that follows seasonal rainfall.

Grasslands support distinctive communities of organisms adapted to open country. Grazing mammals feed on the abundant grasses, and these in turn support predators, forming food webs built around the grassland's plant life. Many grassland plants grow from the base of their leaves, allowing them to recover quickly after being grazed or burned. These ecosystems also include relationships with burrowing animals, insects and birds, and they border other biomes such as desert, chaparral and forest, with which they exchange species and conditions.

Frequently asked questions

What is the difference between steppe and savanna?

Steppe is a temperate grassland of mid-latitudes with cold winters, while savanna is a tropical grassland, often with scattered trees and a distinct wet and dry season.

Why don't trees take over grasslands?

Low and irregular rainfall, periodic fires, drought and grazing by large animals all limit tree growth, allowing fast-recovering grasses to dominate instead.

How do grasses survive grazing?

Many grasses grow from the base of their leaves rather than the tip, so they can regrow quickly after being eaten or burned, unlike many broad-leaved plants.