{{Cleanup|date=September 2007}}

[[Image:Konza1.jpg|thumb|right|240px|The [[Konza Prairie|Konza]] [[tallgrass prairie]] in the [[Flint Hills]] of northeastern [[Kansas]].]]

[[Image:Grasslands-menggu.JPG|thumb|right|240px|An [[Inner Mongolia]]n grassland in the [[People's Republic of China]].]]

'''Grasslands''' (also called '''greenswards''') are areas where the [[vegetation]] is dominated by [[grass]]es ([[Poaceae]]) and other [[herbaceous]] (non-woody) plants ([[forb]]s). However, sedge ([[Cyperaceae]]) and rush ([[Juncaceae]]) families can also be found. Grasslands occur naturally on all continents except [[Antarctica]]. In temperate latitudes, such as north-west [[Europe]], grasslands are dominated by perennial species, whereas in warmer climates annual species form a greater component of the vegetation.<ref name="autogenerated2">[http://earthobservatory.nasa.gov/Laboratory/Biome/biograssland.html NASA Earth Observatory webpage]</ref>

Grasslands can be found in most [[Terrestrial ecoregion|terrestrial]] climates. Grassland vegetation can vary in height from very short, as in chalk [[downland]] where the vegetation may be less than 30 cm high, to quite tall, as in the case of [[North American]] [[tallgrass prairie]], [[South America]]n grasslands and [[Africa]]n [[savanna]]. Woody plants, shrubs or trees, may occur on some grasslands - forming [[savanna]]s, scrubby grassland or semi-wooded grassland, such as the African savannas or the Iberian dehesa. Such grasslands are sometimes referred to as wood-pasture or woodland.

Grasslands cover nearly fifty percent of the land surface of the continent of [[Africa]].<ref name="autogenerated1">[http://www.ucmp.berkeley.edu/exhibits/biomes/grasslands.php University of California Museum of Paleontology Grasslands website]</ref> While grasslands in general support diverse wildlife, given the lack of hiding places for predators, the African Savanna regions support a much greater diversity in wildlife than do temperate grasslands.<ref>[http://www.nceas.ucsb.edu/nceas-web/kids/biomes/grassland.htm University of California- Santa Barbara Temperate Grasslands website]</ref>

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.<ref name="autogenerated1" />

As flowering plants, grasses grow in great concentrations in climates where annual rainfall ranges between 500 mm and 900 mm (approximately 20 to 35 inches).<ref name="autogenerated2" /> The root systems of perennial grasses and forbs form complex mats that hold the soil in place. Mites, insect larvae, nematodes and earthworms inhabit deep soil, which can reach 6 meters (about 20 feet) underground in undisturbed grasslands on the richest soils of the world. These invertebrates, along with symbiotic fungi, extend the root systems, break apart hard soil, enrich it with urea and other natural fertilizers, trap minerals and water and promote growth (Chadwick 1995). Some types of fungi make the plants more resistant to insect and microbial attacks.

==Climate==

Natural grasslands primarily occur in regions that receive between 500 to 900 mm (15 to 30 in) of rain per year, as compared with [[deserts]], which receive less than 300 mm (12 in) and [[tropical rainforests]], which receive more than 2,000 mm (80 in).<ref name="autogenerated1" />. [[Anthropogenic]] grasslands often occur in much higher rainfall zones, as high as 200cm annual rainfall.

Average daily temperatures range between -20 to 30 degrees Celsius.<ref>[http://earthobservatory.nasa.gov/Laboratory/Biome/biograssland.html EO Experiments: Grassland Biome<!-- Bot generated title -->]</ref>. Temperate grasslands have cold winters and warm summers with rain or some snow.

==Grassland biodiversity and conservation==

Grasslands dominated by unsown wild-plant communities ("unimproved grasslands") can be called either natural or 'semi-natural' habitats. The majority of grasslands in temperate climates are 'semi-natural', although their plant communities are natural, their maintenance depends upon anthropogenic activities such as low-intensity farming. Farming maintains these grasslands through grazing and cutting regimes. These grasslands contain many species of wild plants - grasses, sedges, rushes and herbs - 25 or more species per square metre is not unusual.{{Fact|date=September 2007}} Chalk downlands in England can support over 40 species per square metre. In many parts of the world, few examples have escaped agricultural improvement (fertilising, weed killing, ploughing or re-seeding). For example, original North American prairie grasslands or lowland wildflower meadows in the UK are now rare and their associated wild flora equally threatened. Associated with the wild-plant diversity of the "unimproved" grasslands is usually a rich invertebrate fauna; also there are many species of birds that are grassland "specialists" - for example [[snipe]], or the [[Great Bustard]]. Agriculturally improved grasslands, which dominate modern intensive agricultural landscapes, are usually poor in wild plant species due to the original diversity of plants having been destroyed by cultivation,{{Fact|date=September 2007}} the original wild-plant communities having been replaced by sown monocultures of cultivated varieties of grasses and clovers, such as [[Perennial ryegrass]] and White [[Clover]].{{Fact|date=September 2007}} In many parts of the world "unimproved" grasslands are one of the most threatened habitats, and a target for acquisition by wildlife conservation groups or for special grants to landowners who are encouraged to manage them appropriately.

==Human impact and economic importance==

[[Image:Prau.JPG|right|thumb|240px|Grassland in [[Cantabria]], northern [[Spain]].]]

Grasslands are of vital importance for raising livestock for human consumption and for milk and other dairy products.

Grassland vegetation remains dominant in a particular area usually due to grazing, cutting, or natural or man-made fires, all discouraging colonisation by and survival of tree and shrub [[seedling]]s.{{Fact|date=September 2007}} Some of the world's largest expanses of grassland are found in African savanna, and these are maintained by wild herbivores as well as by nomadic pastoralists and their cattle, sheep or goats.{{Fact|date=September 2007}}

Grasslands may occur naturally or as the result of human activity. Grasslands created and maintained by human activity are called '''anthropogenic grasslands'''. Hunting peoples around the world often set regular fires to maintain and extend grasslands, and prevent fire-intolerant trees and shrubs from taking hold. The tallgrass [[prairie]]s in the American Midwest may have been extended eastward into [[Illinois]], [[Indiana]], and [[Ohio]] by human agency. Much grassland in north-west Europe developed after the Neolithic Period, when people gradually cleared the forest to create areas for raising their livestock.

[[Image:Morton Arboretum grassland.jpg|thumb|left|240px|A restored grassland ecosystem at [[Morton Arboretum]] in [[Illinois]].]]

==Types of grassland==

===Tropical and subtropical grasslands===

These grasslands are classified with tropical and subtropical [[savanna]]s and [[shrubland]]s as the [[tropical and subtropical grasslands, savannas, and shrublands]] biome. Notable tropical and subtropical grasslands include the [[Llanos]] grasslands of northern [[South America]].

===Temperate grasslands===

Mid-latitude grasslands, including the [[Prairie]] of [[North America]], the [[Pampa]] of [[Argentina]], calcareous [[downland]], and the [[steppe]]s of [[Europe]]. They are classified with temperate savannas and shrublands as the [[temperate grasslands, savannas, and shrublands]] biome. Temperate grasslands are the home to many large [[herbivores]], such as [[bison]], [[gazelle]]s, [[zebra]]s, [[rhinoceros]]es, and [[wild horse]]s. [[Carnivores]] like [[lion]]s, [[wolf|wolves]] and [[cheetah]]s and leopards are also found in temperate grasslands. Other animals of this region include: [[deer]], [[prairie dog]]s, [[mouse|mice]], [[jack rabbit]]s, [[skunk]]s, [[coyote]]s, [[snake]]s, [[fox]], [[owl]]s, [[badger]]s, [[blackbird]]s, [[grasshopper]]s, [[meadowlark]]s, [[sparrow]]s, [[quail]]s, [[hawk]]s and hyenas.

===Flooded grasslands===

Grasslands that are flooded seasonally or year-round, like the [[Everglades]] of [[Florida]] or the [[Pantanal]] of [[Brazil]], [[Bolivia]] and [[Paraguay]].They are classified with flooded savannas as the [[flooded grasslands and savannas]] biome and occur mostly in the tropics and subtropics.

===Montane grasslands===

High-altitude grasslands located on high [[mountain ranges]] around the world, like the [[Páramo]] of the [[Andes Mountains]]. They are part of the [[montane grasslands and shrublands]] biome, and also constitute [[tundra]].

===Polar grasslands===

Similar to montane grasslands, [[arctic tundra]] can have grasses. However high soil moisture means that few tundras are grass-dominated today. However, during the [[Pleistocene]] [[ice age]]s, a polar grassland known as [[steppe-tundra]] occupied large areas of the Northern hemisphere.

===Xeric grasslands===

Also called '''desert grasslands''', these are sparse grasslands located in [[deserts and xeric shrublands]] ecoregions.

==See also==

*[[Appalachian bald]]

*[[Coastal plain]]

*[[Dambo]]

*[[Desert]]

*[[Field (agriculture)|Field]]

*[[Flooded grasslands and savannas]]

*[[Flood-meadow]]

*[[Llanos]]

*[[Meadow]]

*[[Pampa]]

*[[Pasture]]

*[[Plain]]

*[[Plateau]]

*[[Prairie]]

*[[Savanna]]

*[[Sods]]

*[[Steppe]]

*[[Taiga]]

*[[Tundra]]

*[[Veld]]

*[[Water-meadow]]

*[[Wet meadow]]

== References ==

{{reflist}}

{{commonscat|Grasslands}}

[[Category:Grasslands| ]]

[[Category:Agricultural land]]

[[af:Grasveld]]

[[da:Græsslette]]

[[de:Grünland]]

[[es:Pradera]]

[[eo:Herbejo]]

[[ko:초원]]

[[hr:Travnjak]]

[[it:Prateria]]

[[nl:Grasland]]

[[ja:草原]]

[[no:Gresslette]]

[[pt:Pradaria]]

[[qu:Inkill]]

[[sv:Gräsmarker]]

[[ta:புல்வெளி]]

[[zh:草原]]