Grasslands occur naturally on all continents except Antarctica.
Grasslands are generally open and continuous, fairly flat areas of grass. They are often located between temperate forests at high latitudes and deserts at subtropical latitudes.
There are two main kinds of grasslands: tropical (savanna) and temperate (prairies or plains).
A savanna or savannah is characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of grasses. Savannas are also characterised by seasonal water availability, with the majority of rainfall confined to one season.
Savannas are mostly located near the equator. The largest expanses of savanna are in Africa. They cover almost half of Africa, more than 13 million square kilometers (5 million square miles). Other major savannas are situated in South America, Northern Australia, India, the Myanmar (Burma)–Thailand region in Asia. Savanna covers approximately 20% of the Earth’s land area.
The species of animals in a savanna depends upon the geographic location of the biome. The African savannah, the savannah with which most people are familiar, is home to a wide variety of animals. A short list of some of those animals includes wildebeest, warthogs, elephants, zebras, rhinos, gazelles, hyenas, cheetahs, lions, leopards, ostrich, starlings, and weavers.
Temperate grasslands are also often referred to as prairies or plains. A composition of grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type. Temperate grassland regions include the Pampas of Argentina, Brazil and Uruguay, and the steppe of Ukraine, Russia and Kazakhstan. Lands typically referred to as “prairie” tend to be in North America. The term encompasses the area referred to as the Interior Lowlands of Canada, the United States, and Mexico, which includes all of the Great Plains as well as the wetter, hillier land to the east.
Grasses vary in size from 2.1 m (7 ft) tall with roots extending down into the soil 1.8 m (6 ft), to the short grasses growing to a height of only 20 to 25 cm (8 to 10 in) tall. These short grasses can have roots that extend 1 m (about 3 ft) deep.
The grasses die back to their roots annually and the soil and the sod protect the roots and the new buds from the cold of winter or dry conditions. A few trees may be found in this biome along the streams, but not many due to the lack of rainfall.
Temperate grasslands have a low diversity of wildlife, but a high abundance of wildlife. In North America the dominant grazing animals are bison and pronghorn. Rodents include pocket gophers and prairie dogs. Carnivores include wolves, coyotes, foxes, badgers and ferrets. Grassland birds such as mountain plovers and burrowing owls nest in prairie dog colonies.
While temperatures are often extreme in some grasslands, the average temperatures are about -20 to 30°C (-4 to 86°F).
Years of extreme drought are more common in grassland than in forested areas, and such droughts may kill even mature trees. But grasses and other grassland plants have extensive root systems that help them survive drought periods.
Prior to the European settlement of North America, the largest grasslands in the United States stretched across the Great Plains from the Rocky Mountains and deserts of the southwestern states to the Mississippi River.