are areas where the vegetation
is dominated by grasses
); however, sedge (Cyperaceae
) and rush (Juncaceae
) families can also be found along with variable proportions of legumes
, like clover
, and other herbs
. Grasslands occur naturally on all continents except Antarctica
. Grasslands are found in most ecoregions
of the Earth
. For example, there are five terrestrial ecoregion
classifications (subdivisions) of the temperate grasslands, savannas, and shrublands biome
), which is one of eight terrestrial ecozones
of the Earth's surface.
Grassland vegetation can vary in height from very short, as in chalk grassland, to quite tall, as in the case of North American tallgrass prairie, South American grasslands and African savanna.
Woody plants, shrubs or trees may occur on some grasslands – forming savannas, scrubby grassland or semi-wooded grassland, such as the African savannas or the Iberian dehesa.
As flowering plants and trees, grasses grow in great concentrations in climates where annual rainfall ranges between 500 and 900 mm (20 and 35 in). The root systems of perennial grasses and forbs form complex mats that hold the soil in place.
Graminoids are among the most versatile life forms. They became widespread toward the end of the Cretaceous period, and fossilized dinosaur feces (coprolites) have been found containing phytoliths of a variety of grasses that include grasses that are related to modern rice and bamboo.
The appearance of mountains in the western United States during the Miocene and Pliocene epochs, a period of some 25 million years, created a continental climate favorable to the evolution of grasslands. Existing forest biomes declined, and grasslands became much more widespread. Following the Pleistocene ice ages, grasslands expanded in range in the hotter, drier climates, and began to become the dominant land feature worldwide.
This page was last edited on 20 June 2018, at 01:46 (UTC)
under CC BY-SA license.