Grasslands

Grasslands are areas of land that are dominated by one or more forms of grass, which is a family of plants that also includes cereals. Grasslands are one of the most common forms of land cover of the nonsubmerged land of the world. The intensification of agriculture in many parts of the world has significantly increased the proportion of land that is considered grassland. Natural grasslands are less prevalent, but still extensive, and have formed in areas in which climatic conditions in terms of water resources are not so beneficial as to permit the creation of forests, but are not so harsh as to lead to the formation of deserts.

The most important grassland areas are the steppe lands of central Asia and southern Russia, extending down to the Indian subcontinent. This area saw the emergence of a stream of nomadic peoples including the Huns, Mongols, Bulgars, and Scythians who, stimulated largely by climate change, launched waves of invasion and conquest over the settled peoples who occupied the surrounding ground. Other areas of grassland include the wide swathe of territory extending from west to east Africa that helped stimulate the creation of temporal states. The large area of central-northern Australian grassland is very lightly inhabited, although it provides a natural home for sheep. In the United States, the prairie is a form of grassland that extends through much of the central section of the country down to the southeastern coastline. This area has long formed a destination for settlers who wish to own land, and represents the center of the intensive agricultural system that sustains the rising population of the country.

Grasslands generally merge into similar forms of land cover at their margins, becoming savanna, scrubland, or other types as the climatic and water resources conditions vary. In some cases, these conditions can prevent grasslands forming in otherwise favorable conditions. For example, extensive flooding can inhibit the growth of larger plants while permitting grasses to flourish for most of the year. Climate change has also been influential in determining the extent of grassland and unanticipated change in status could be disastrous. The extensive burning of original forest by early settlers created the grasslands of the South Island of New Zealand, which sustain the nation's sheep industry. Fire is a regular occurrence in grassland during hot conditions, and these fires are capable of running out of control and threatening human habitation, given the close proximity with which people live to agricultural areas. Burning of stubble or abandonment of previously worked agricultural land might also change the nature of existing or potential grassland. The suitability of grasslands for supporting animal husbandry and cereal crops means that grassland management and manipulation have been studied in considerable depth, and productivity levels have been increased considerably.

Because of development and other land cover transformations from human occupation, grasslands are increasingly in decline throughout the world, especially in North America. The concomitant loss of floral and avian biodiversity that depends on these ecosystems represents a serious, and largely underappreciated, global ecological crisis.

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