Grasslands are areas where the vegetation is dominated by grasses, however sedge and rush families can also be found. Grasslands occur naturally on all continents expect Antarctica. Grasslands are found in most ecoregions of the Earth. For example: There are five terrestrial ecoregion classifications (subdivision) of the temperate grasslands, savannas, and scrublands biome, which is one of eight terrestrial Eco zones of the Earth’s surface.
VEGETATION:
Grassland vegetation can vary in height from very short, as in chalk where the vegetation may be less than 30cm (12in) high, to quite tall, as in the case North American tall grass prairie, South American grasslands and African savannas.
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. Such grasslands are sometimes referred to as wood-pasture or woodland.
As flowering plants, grasses grow in great concentrations in climates where annual rainfall ranges between 500 and 900mm (20 and 35 in). The root systems of perennial grasses and forbs form complex mats that hold the soil in place.
CLIMATE:
Grasslands often occur in areas with annual precipitation between 600 mm (24 in) and 1,500 mm (59 in) and average mean an annual temperature ranges from −5 and 20 °C (Woodward et al. 2004). However, some grasslands occur in colder (-20°C) and hotter (30°C) climatic conditions. Grassland can exist in habitats that are frequently disturbed by grazing or fire; as such disturbance prevents the encroachment of woody species. Species richness is particularly high in grasslands of low soil fertility such as serpentine barrens and calcareous grasslands. Infertility may also prevent woody encroachment as low nutrient levels in the soil may inhibit the growth of forest and shrub species. Most plants from growing. Temperate grasslands occur in temperate climates typified by distinct seasonality (warm summers and cold winters).
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, which maintains these grasslands through grazing and cutting regimes. These grasslands contain many species of wild plants – grasses, sedges, rushes and herbs – 25 or more spherical 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", such as the snipe and 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, 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.
In many parts of the world "unimproved" grasslands are one of the least 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:
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 manmade fires, all discouraging colonisation by and survival of tree and shrub seedlings. Some of the world's largest expanses of grassland are found in African Savannas, and these are maintained by wild herbivores as well as by nomadic pastoralists and their cattle, sheep or goats.
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 tall grass prairies in the US Midwest may have been extended eastward into Illinois, Indiana, and Ohio by human agency. Much grassland in northwest Europe developed after the Neolithic Period, when people gradually cleared the forest to create areas for raising their livestock.