Tallgrass prairie

Historically, natural and anthropogenic fire, as well as grazing by large mammals (primarily bison) provided periodic disturbances to these ecosystems, limiting the encroachment of trees, recycling soil nutrients, and facilitating seed dispersal and germination.

Prior to widespread use of the steel plow, which enabled large scale conversion to agricultural land use, tallgrass prairies extended throughout the American Midwest and smaller portions of southern central Canada, from the transitional ecotones out of eastern North American forests, west to a climatic threshold based on precipitation and soils, to the southern reaches of the Flint Hills in Oklahoma, to a transition into forest in Manitoba.

In the northeast, where fire was infrequent and periodic windthrow represented the main source of disturbance, beech-maple forests dominated.

In contrast, shortgrass prairie was typical in the western Great Plains, where rainfall is less frequent, and soils are less fertile.

Retreating glaciers deposited the parent material for soil in the form of till, i.e. unsorted sediment, about 10,000 years ago.

Wind-dropped loess and organic matter accumulated, resulting in deep levels[citation needed] of topsoil.

Prairie dogs, a type of squirrel and considered to be a keystone species, dug tunnels, turning the soil and allowing water to travel several feet underground.

Estimates differ of how much original tallgrass prairie survives, ranging from less than 1% mostly in "scattered remnants found in pioneer cemeteries, restoration projects, along highways and railroad rights-of-way, and on steep bluffs high above rivers"[1] to 4%.

[6] As its name suggests, the most famous members of the tallgrass prairie are tall warm-season grasses, such as indiangrass (Sorghastrum nutans), big bluestem (Andropogon gerardi), and switchgrass (Panicum virgatum), which average between 4.9 and 6.6 ft (1.5 and 2 m) tall, and little bluestem (Schizachyrium scoparium), which is typically up to 3.3 ft (1 m).

The tallgrass prairie survives in areas unsuited to plowing: the rocky hill country of the Flint Hills, which runs north to south through east-central Kansas; the eastern fringe of the Red River Valley (Tallgrass Aspen Parkland) in Manitoba and Minnesota; the Coteau des Prairies, which extends from South Dakota through Minnesota and into Iowa; and the far north portion of Oklahoma.

In Oklahoma, the tallgrass prairie has been maintained by ranchers, who saw the hat-high grass as prime grazing area for cattle.

The original extent of tallgrass prairie in Canada was the 2,300-square-mile (6,000 km2) plain in the Red River Valley, southwest of Winnipeg in Manitoba (see map).

The Manitoba Tall Grass Prairie Preserve, which occupies small portions of the municipalities of Stuartburn and Emerson – Franklin, forms a part of the Tallgrass Aspen Parkland.