The Great Plains - Overview

Doug Sokell/Tom Stack and Associates©

by
Science Editor
Gary D. Willson
National Biological Service
Northern Prairie Science Center
Central Plains/Ozark Field Station
University of Missouri
316 Gentry Hall
Columbia, MO 65211

The Great Plains
*Overview*
The Great Plains of North America are grasslands or former grasslands that occupy more than 200 million ha (500 million acres) of land from central Alberta, Canada, to the Texas Panhandle and eastern New Mexico and from the front range of the Rocky Mountains to the forest edge in Minnesota, Missouri, and Oklahoma. The natural plant communities dominating this landscape are known as grasslands or prairie (French for meadow) and they are composed of a rich complex of grasses and forbs. The climate, soils, and topography of the eastern Great Plains are suitable for agriculture, and consequently most of the original prairie has been converted to row crops or pasture. In the western Great Plains, large areas of intact grassland are used as rangeland. Researchers estimate that less than 1% of the original grasslands remains undisturbed by human activities (Klopatek et al. 1979).
Articles in this section focus on the effects of more than 100 years of postsettlement manipulation of the Great Plains ecosystem. For example, fire was undoubtedly an important ecological force in maintaining historical grassland landscapes and species distributions. Following fire suppression, woody plants have invaded grasslands from adjacent forest and wooded stream valleys. In addition, water management practices and the planting of farm and ranch shelterbelts have resulted in the encroachment of trees into grassland habitat. In many parts of the Great Plains today, far more woody plants exist than before agricultural development. As endemic grassland birds have declined, they have been replaced by eastern forest species moving into newly wooded habitats (Knopf; Igl and Johnson, both this section).
Native prairie fishes also have experienced significant losses in their historical distributions. Impoundments constructed on many rivers and streams of the Great Plains have fragmented populations and eliminated colonization of vacant habitat. Several prairie fishes, including the Arkansas River shiner (Notropis girardi) and the Arkansas River speckled chub (Macrhybopsis aestivalis tetranemus), have shown significant declines in their distributions and abundances (Echelle et al., this section).
The fragmentation of native grassland due to agricultural encroachment as well as the elimination of keystone species, such as bison (Bison bison) and the white-tailed prairie dog (Cynomys leucurus), have led to a general decline in prairie wildlife, although some species have adapted to human-induced changes and some have even increased in numbers. For example, native grassland birds have shown steeper, more consistent, and more geographically widespread declines than any other avian group, including Neotropical migrants (Knopf, this section). Species such as mallard (Anas platyrhynchos), blue-winged teal (A. discors), and northern pintail (A. acuta) are now at or near the lowest numbers ever recorded (Shaffer and Newton, this section). The primary reason for these declines in numbers is low nest success due to predation by common species such as red fox (Vulpes vulpes; Shaffer and Newton, this section). In other species, such as American coot (Fulica americana), drainage of wetlands compounded by severe drought may have played a role in depressing populations (Igl and Johnson, this section). In contrast to waterfowl, the coyote (Canis latrans) is increasing its range. Historical and recent trends in coyote populations and diet may reflect a response to land-use changes, especially agricultural changes and shifts in human populations on the Great Plains (Gipson and Brillhart, this section).
The Great Plains are becoming increasingly rural because of emigration of people and a shift of human populations away from farms to urban centers. Although the Great Plains encompass about 20% of the land mass of the lower 48 states, the population is only about 2% of the U.S. total. Federal agricultural land-retirement programs, such as the Soil Bank Program and the Conservation Reserve Program (CRP), devised to mediate fluctuations in the farm economy, may also help slow or reverse the declines of some grassland species. For example, recent field surveys have shown that several grassland birds that had declined in the Great Plains are much more common on CRP habitat than in cropland (Johnson and Koford, this section). In recent years numerous small to medium tracts of native grassland have been designated as preserves. These areas plus changes in agricultural practices that promote natural resource conservation (e.g., CRP) are important to protect the remaining biodiversity of the Great Plains.

References
Klopatek, E.V., R.J. Olson, C.J. Emerson, and J.L. Jones. 1979. Landuse conflicts with natural vegetation. Environmental Conservation 6:191-200.