Grasslands Habitat
Grasslands are areas dominated by grasses and forbs, and have few or no trees. Grazing and roaming animals occur in abundance. They occupy about one quarter of the Earth's land area.
Legal Status/Protection
Less than 8 percent of all grasslands worldwide are protected. The lowest protection of any biome on earth is temperate grasslands, at less than 1 percent. This includes North America’s Great Plains.
Types of Habitat
Grasslands are divided into two main types: temperate grasslands and tropical grasslands, commonly called savannas.
Temperate Grasslands
Location
Temperate grasslands are located north of the Tropic of Cancer (23.5 degrees North) and south of the Tropic of Capricorn (23.5 degrees South). The major temperate grasslands include the veldts of Africa, the pampas of South America, the steppes of Eurasia, and the plains of North America.
Plants
Grasses are the dominant vegetation. Trees and large shrubs are largely absent. Seasonal drought, occasional fires and grazing by large mammals all prevent woody shrubs and trees from becoming established. A few trees such as cottonwoods, oaks and willows grow in river valleys, and a few hundred species of flowers grow among the grasses. The various species of grasses include purple needlegrass, blue grama, buffalo grass, and galleta. Flowers include asters, blazing stars, coneflowers, goldenrods, sunflowers, clovers, psoraleas, and wild indigos.
Animals
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, swift foxes, badgers and black-footed ferrets. Birds include grouses, meadowlarks, quails, sparrows, hawks and owls.
Climate
Temperate grasslands have hot summers and cold winters. Summer temperatures can be well over 100 degrees Fahrenheit, while winter temperatures can be as low as -40 degrees Fahrenheit. They typically have between 10 and 35 inches of precipitation a year, much of it occurring in the late spring and early summer. Snow often serves as a reservoir of moisture for the beginning of the growing season. Seasonal drought and occasional fires help maintain these grasslands.
Soil
Temperate grasslands have soils that are nutrient-rich from the growth and decay of deep, many-branched grass roots. The rotted roots hold the soil together and provide a food source for living plants. The world's most fertile soils underlie the eastern prairies of the US, the pampas of South America, and the steppes of Ukraine and Russia.
Threats
Overgrazing by livestock and plowing are the two greatest threats to temperate grasslands. Since the development of the steel plow much of these grasslands have been converted to agricultural lands because of their rich soil. About 47 percent of temperate grasslands have been converted to agriculture or urban development. Lack of fire and fragmentation are also threats, as is past and present wildlife eradication (including the bison slaughter of the 1800s and ongoing prairie dog poisoning in North America’s plains).
Tropical Grasslands (Savannas):
Location
Tropical grasslands are located near the equator, between the Tropic of Cancer and the Tropic of Capricorn. They cover much of Africa as well as large areas of Australia, South America, and India.
Plants
Tropical grasslands are dominated by grasses, often 3 to 6 feet tall at maturity. They may have some drought-resistant, fire-resistant or browse-resistant trees, or they may have an open shrub layer. They develop in regions where the climax community should be forest, but drought and fire prevent the establishment of many trees.
Animals
Tropical grassland animals (which do not all occur in the same area) include giraffes, zebras, buffaloes, kangaroos, mice, moles, gophers, ground squirrels, snakes, worms, termites, beetles, lions, leopards, hyenas, and elephants. The world's greatest diversity of ungulates (hoofed mammals) is found on the savannas of Africa. The antelopes are especially diverse and include eland, impalas, gazelles oryx, gerenuk and kudu. Buffalo, wildebeest, plains zebra, rhinos, giraffes, elephants and warthogs are among other herbivores of the African savanna. Carnivores include lions, leopards, cheetahs, jackals, wild dogs and hyenas. Termites are especially abundant in the tropical grasslands of the world.
Climate
Tropical grasslands are found in tropical wet and dry climates. These areas are hot year-round, usually never dropping under 64 degrees Farenheit. Although these areas are overall very dry, they do have a season of heavy rain. Annual rainfall is from 20-50 inches per year. It is crucial that the rainfall is concentrated in six or eight months of the year, followed by a long period of drought when fires can occur. If the rain were well distributed throughout the year, many such areas would become tropical forest.
Soil
The soil of tropical grasslands is porous, with rapid drainage of water. It has only a thin layer of humus (the organic portion of the soil created by partial decomposition of plant or animal matter), which provides vegetation with nutrients.
Threats
Poaching, overgrazing and clearing of the land for crops are the main threats. About 16 percent of tropical grasslands have been converted for agriculture or urban development. Desertification is also a significant threat.
