Tallgrass Prairie

The tall grass prairie is an ecosystem native to central North America, with fire as its primary periodic disturbance. In the past, tall grass prairies covered a large portion of the American Midwest, just east of the Great Plains, and portions of the Canadian Prairies. They flourished in areas with rich loess soils and moderate rainfall of around 30 to 35 inches per year. To the east were the fire-maintained eastern savannas. In the northeast, where fire was infrequent and periodic wind throw represented the main source of disturbance, beech-maple forests dominated.

Once this prairie covered approximately 140 million acres; now only isolated remnants exist. (Heat-Moon 261). The homesteaders saw it as a nuisance to be replaced as soon as possible with crops that paid their way. Within one generation a great majority of the native land was plowed under and developed. Currently, less than 4% remains, while the majority is located in the Kansas Flint Hills and surrounding areas. (Manning 76). Today, prairie is being brought back in places using a land management technique borrowed from the Plains tribes: controlled burning.

Spring fires clear out non-native grasses before the later “sun-seeking” native grasses begin to grow. ( Heat-Moon 43-44). Fire also burns up dead plant debris on the ground, allowing the sun and rain to penetrate the soil, and releases nutrients, promoting growth and increasing seed yields. This and other prairie restoration methods help ensure that, at least in some places, we can look out over a sea of grass and feel the wonder of the first homesteaders.

According to a long-term research study on tall grass prairies done at the Konza Prairie Research Natural Area by a trio of Kansas State University biology professors, bison grazing or mowing increases the species diversity or the number of plant species that exist at a particular site of grasses on the prairie. (KSU 1). Grazing and mowing keep plant diversity high even in annually burned or fertilized prairie where some plant species would otherwise be lost. Their research was published today in the journal Science.

Alan Knapp, John Blair and John Briggs, along with two other colleagues have been conducting long-term studies on the effects of fire, grazing and climatic variability on tall grass prairies. This on-going research looks at these various factors alone and in combination. “One of the things we have learned in the past is that if you burn a prairie annually, species diversity tends to decrease,” Knapp said. “Grazing the prairie or removing part of the plant canopy, tends to offset the effects of frequent burning. Knapp said the re-introduction of bison, the prairie’s native herbivores, over the past decade also has increased species diversity. (Cushman 13).

“Bison, which were historically a very abundant herbivore on the tall grass prairies, played an important role in maintaining the plant species diversity in these systems,” Knapp said. “The increase in plant diversity we see at Konza Prairie after bison are re-introduced can be related to increases with bison grazing activities. (KSU 1). The bison that once roamed these prairies numbered close to 30 million, once settlers began to encroach on the area, and began to use the land for homesteading and agriculture the numbers dipped to nearly 500 individuals. As the bison left, the domestic cattle moved in with the homesteaders, once again disrupting the natural biodiversity of the land. In addition to the loss of the bison, fire on the prairie was a key element as well. (White 88).

Typically, prairie fires were naturally occurring due to lightening strikes, and were in fact beneficial. As people began to settle and live in these areas these fires were seen as a hindrance, and were extinguished as quickly as possible. (Savage 124-26). These actions were not favorable for the grasses as these fires typically helped the natural species regenerate and helped to keep trees at bay as well. As time went on, the more human interaction that took place, the more it was destroying the natural tall grass prairie as it once was.