A prairie is an area of land of low topographic relief that principally supports grasses and herbs, with few trees, and is generally of a mesic (moderate or temperate) climate. Most of the Great Plains, most of the states of Ohio, Indiana, Illinois and Iowa, and much of Missouri and Minnesota is considered prairie. French explorers called these areas "prairie", from the French word for "meadow". Almost all of this area has been converted into farmland in the last two hundred years.
Fire is an important part of prairie ecology; natural and human induced fires were common in historic prairie areas. Grazing by animals such as the American Bison and Prairie dogs also helped maintain the original prairie ecology. Prairies were also artificially created by Native Americans in eastern North America by periodic burning. One such area was along the southwestern shore of Lake Erie in what is now Pennsylvania and New York; another was between Seneca Lake and Cayuga Lake in present New York.
Prairies are considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type. Other temperate grasslands regions include the Pampas of Argentina, and the steppes of Russia and Ukraine.
Significant preserved areas of prairie include: