Thetallgrass prairie is anecosystem native to centralNorth America. Historically, natural andanthropogenic fire, as well as grazing by large mammals (primarilybison) 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, tallgrassprairies extended throughout theAmerican Midwest and smaller portions of southerncentral 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 theFlint Hills in Kansas, to a transition into forest in Manitoba.
They were characteristically found in parts of the upper Mississippi River Valley, in thecentral forest-grasslands transition, thecentral tall grasslands, theupper Midwest forest-savanna transition, and thenorthern tall grasslandsecoregions. They flourished in areas with richloess soils and moderate rainfall around 30-35 inches (700–900 mm) per year. To the east were thefire-maintainedeastern savannas. In the northeast, where fire was infrequent and periodicwindthrow represented the main source of disturbance,beech-maple forests dominated. In contrast,shortgrass prairie was typical in the westernGreat Plains, where rainfall is less frequent, and soils are less fertile. Due to expansive agricultural land use, very little tallgrass prairie remains.
Retreating glaciers deposited the parent material for soil in the form oftill, i.e. unsorted sediment, about 10,000 years ago. Wind-droppedloess and organic matter accumulated, resulting in deep levels[citation needed] oftopsoil. Animals, such as bison, elk, deer, and rabbits, added nitrogen to the soil through urine and feces.Prairie dogs, a type of squirrel and considered to be akeystone species, dug tunnels, turning the soil and allowing water to travel several feet underground.[1]
For 5,000 to 8,000 years, more than 240 million acres (970,000 km2) of prairie grasslands were a major feature of the landscape.[2] Between 1800 and 1930, the vast majority was destroyed. Settlers transformed what they named "the Great American Desert" or "The Inland Sea" into farmland. Major reasons for the prairie's demise were the confined grazing pattern of European cattle versus bison, the near-extermination of prairie dogs, and the plowing and cultivation of the land, which breached tallgrass root systems and interrupted reproduction. Furthermore, extensivetile drainage has changed the soil's water content and hydrodynamics, and ongoing soil erosion results in its increasing loss.
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%.
Tallgrass prairie is capable of supporting significant biodiversity. According to theWorld Wildlife Fund, parts of the ecoregion are among the "top ten ecoregions for reptiles, birds, butterflies, and tree species. Tallgrass species are found in the understory layer."[3] Oak, such asblackjack oak (Quercus marilandica) andpost oak (Q. stellata), andhickory tree species occur in some areas, but generally in moderate densities.Bison (Bison bison) were a dominant species.[3]
The tallgrass prairiebiome depends on prairie fires, a form ofwildfire, for its survival and renewal.[4] Tree seedlings and intrusivealien species without fire tolerance are eliminated by periodic fires. Such fires may either be set by humans (for example, Native Americans used fires to drive bison and improve hunting, travel, and visibility) or started naturally by lightning.[5]
White-tailed deer fecal matter has nutrients for plant biodiversity in Tallgrass prairie area.[6]
As its name suggests, the most famous members of the tallgrass prairie are tall warm-seasongrasses, 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). Remnant prairies typically have a larger number of shorter grasses, such as prairie dropseed (Sporobolus heterolepis), porcupine grass (Hesperostipa spartea), and Leiberg's panic grass (Dichanthelium leibergii) in the Upper Midwest.[7] Prairies also include a large percentage offorbs, such as lead plant (Amorpha spp.), prairierosinweed (Silphium spp.), gayfeathers (Liatris spp.), sunflowers (Helianthus spp.), asters (Symphyotrichum spp.),coneflowers (Echinacea spp., andRudbeckia spp.), and many other species.
Technically, prairies have less than 5–11%[clarification needed] tree cover.[citation needed] A grass-dominated plant community with 10–49% tree cover is asavanna.
After the steelplow was invented byJohn Deere in 1833,[8] this fertile soil became one of America's most important resources. Over 95% of the original tallgrass prairie is nowfarmland.
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The tallgrass prairie survives in areas unsuited to plowing: the rocky hill country of theFlint Hills, which runs north to south through east-centralKansas; the eastern fringe of the Red River Valley (Tallgrass Aspen Parkland) inManitoba and Minnesota; theCoteau des Prairies, which extends fromSouth Dakota throughMinnesota and intoIowa; and the far north portion ofOklahoma. In Oklahoma, the tallgrass prairie has been maintained by ranchers, who saw the hat-high grass as primegrazing area forcattle.
The 39,000-acre (158 km2)Tallgrass Prairie Preserve inOsage County, Oklahoma, and the somewhat smaller 10,900-acre (44.1 km2)Tallgrass Prairie National Preserve in Kansas, attempt to maintain this ecosystem in its natural form. They have reintroducedplains bison to the vast expanses of grass.[4] Other U.S. preserves includeMidewin National Tallgrass Prairie in Illinois,Broken Kettle Preserve andNeal Smith National Wildlife Refuge in Iowa,Konza Prairie in Kansas, andPrairie State Park in Missouri. In easternNorth Dakota isSheyenne National Grassland, the onlynational grassland on the tallgrass prairie. Also, several small tallgrass prairie reservations are inCook County,Illinois, including theNational Natural Landmark,Gensburg-Markham Prairie.[9] Tallgrass prairie remnants can also be found among nature preserves in theHobart Nature District, located in Hobart, Indiana, just outside of Chicago.
The original extent of tallgrass prairie in Canada was the 2,300-square-mile (6,000 km2) plain in theRed River Valley, southwest ofWinnipeg in Manitoba (see map).[10] While most of Manitoba's tallgrass prairie has been destroyed through cultivation and urban expansion, relatively small areas persist. One of the largest blocks of remaining tallgrass prairie in Manitoba is protected by several conservation partners in a conservation area called the Tallgrass Aspen Parkland. TheManitoba Tall Grass Prairie Preserve, which occupies small portions of the municipalities ofStuartburn andEmerson – Franklin, forms a part of the Tallgrass Aspen Parkland. This preserve contains about 4,000 ha (9,900 acres) of tallgrass prairie,aspen parkland, and wetlands.
A small pocket of less than 1,200 acres (5 km2) of tallgrass prairie remains in the southwest corner ofWindsor, Ontario, protected byOjibway Park, and Spring Garden Area of Natural Scientific Interest, along with the interconnected parks:Black Oak Heritage Park,Ojibway Prairie Provincial Nature Reserve, and theTallgrass Prairie Heritage Park. Aside from the Provincial Nature Reserve, all are operated by the City of Windsor's Parks and Recreation.
Considered the birthplace ofecological restoration, thefirst tallgrass prairie restoration was the 1936 Curtis Prairie at theUniversity of Wisconsin-Madison Arboretum.[11] The UW Arboretum was the center of tallgrass prairie research through the first half of the 20th century, with the development of the nearby Greene Prairie,Aldo Leopold Shack and Farm and pioneering techniques likeprescribed burning.[12] The latter half of the 20th century saw the growth of tallgrass prairie restoration beyond Wisconsin borders, with projects in Illinois such as atKnox College,College of DuPage,Morton Arboretum, andFermi National Laboratory, and projects in Iowa includingGrinnell College'sConard Environmental Research Area. These major tallgrass restoration projects marked restoration's growth from isolated studies to widespread practice. Tallgrass prairie restoration efforts picked up wider public recognition in the 1980s, spurred by the publication of a book of appreciation,John Madson'sWhere the Sky Began: Land of the Tallgrass Prairie (1982).[13] Nonprofit organizations throughout the former tallgrass prairie region began to reserve or restore small remnants of native prairie. For example, the Native Prairies Association of Texas was founded in 1986 to locate, restore, and protect prairies in Texas; the group currently protects about 2,780 acres (11.3 km2) of Texas prairies.[14]
TheMidewin National Tallgrass Prairie, founded in 1996 nearElwood, Illinois, was, as of 2006, the largest tallgrass prairie restoration area in the United States. In Minnesota,Glacial Ridge National Wildlife Refuge was established in 2004. The core of the refuge is a preserved 5,000-acre (20 km2) tallgrass prairie remnant, and an additional 30,000 acres (121 km2) are either in the process of restoration or will be soon. According toThe Nature Conservancy, so far, 100 wetlands have been restored, and 8,000 acres (32 km2) of land has been seeded with native plant species.[15]
Several books have been published on tallgrass prairie restoration, including:
