Central Tallgrass Prairie

This system is found primarily in the Central Tallgrass Prairie ecoregion ranging from eastern Kansas and Nebraska to northwestern Indiana. This system differs from other prairie systems to the north and south by being the most mesic with primarily deep, rich Mollisol soils. These soils are usually greater than 1 meter deep. This system is dominated by tallgrass species such as Andropogon gerardii, Sorghastrum nutans, and Panicum virgatum. These species typically grow to 1-2 m tall in the rich soils found in this system. Other mid- and shortgrass species, such as Bouteloua curtipendula, Hesperostipa spartea, and Schizachyrium scoparium, are usually present and can be common or locally dominant on patches of this system, particularly slopes or other areas with drier habitats. Several forb species are also associated with this system making it one of the most diverse grassland systems. As many as 300 herbaceous plant species could occur on a 10-ha high-quality example of this system across its range. Historically, fires limited woody species; however, the current environment and habitat of this system do not prevent invasion by shrubs and trees. High-quality examples of this system have trees and shrubs widely scattered or clustered in areas that are wetter and/or more sheltered from fire than the surrounding grassland. Fire, drought, and grazing are the primary natural dynamics influencing this system and help prevent woody species from invading. However, conversion to agriculture has been the prime disturbance since European settlement. The rich soils and long growing season make this an ideal location for farming row crops, and as a result very few examples of this system remain.

This system is dominated by tallgrass species such as Andropogon gerardii, Sorghastrum nutans, and Panicum virgatum. These species typically grow to 1-2 m tall in the rich soils found in this system. Other mid- and shortgrass species, such as Bouteloua curtipendula, Hesperostipa spartea, and Schizachyrium scoparium, are usually present and can be common or locally dominant on patches of this system, particularly slopes or other areas with drier habitats. Several forb species are also associated with this system making it one of the most diverse grassland systems. As many as 300 herbaceous plant species could occur in this system across its range. The environment and habitat of this system do not prevent invasion by shrubs and trees. High-quality examples of this system have trees and shrubs widely scattered or clustered in areas that are wetter and/or more sheltered from fire than the surrounding grassland.

This system differs from other prairie systems to the north and south by being the most mesic with primarily deep, rich Mollisol soils. These soils are usually greater than 1 m deep and organic matter is high. Litter can build up if sites are not burned or grazed for several years. This system occurs in a climate that allows the growth of trees and shrubs. These are kept out of the prairies largely by fires and periodic drought, so the prairies tended to be on flat to rolling topography with fewer firebreaks (wetlands, rivers, or steeply dissected topography).

Fire, drought, and grazing are the primary natural dynamics influencing this system and help prevent woody species from invading. This system is found in a climate that can support trees and shrubs but woody vegetation is inhibited by frequent fires. Historically, fire-return intervals were short, estimated at between 2 and 5 years (Stambaugh et al. 2006, Landfire 2007a). The frequent but unpredictable hot fires created a patchwork of habitats across the landscape, with recently burned sites having less litter and forb cover and sites with infrequent fires possibly having more woody species and dense stands of grasses (Kucera and Koelling 1964). This system developed in an area with large numbers of native ungulates, notably bison (Bos bison) but including other species (elk and deer), and the grazing of these species affected species composition and the patchwork of habitat. Bison were likely more numerous and thus had more effect in the western portion of this system's range. Bison preferentially favor newly burned areas and graminoids over forbs (Vinton et al. 1993, Coppedge and Shaw 1998). Their grazing, trampling, and wallowing were important in creating habitat diversity across the landscape (Knapp et al. 1999). On unburned sites, grazing removes live and dead vegetation, allowing more light and heat to the soil surface and increasing available moisture thus favoring species, forbs or woody plants, in the case of bison grazing, that were resilient to the effects of grazing or avoided by the grazers (Damoureyeh and Hartnett 1997).

Tallgrass prairie has been largely eliminated from the landscape due to conversion to agricultural uses, elimination of the landscape-level processes that maintained the system, and introduction of exotic species. Estimates across the range of all tallgrass prairie systems are that 82-99.9% of tallgrass prairie has been eliminated (reported in Samson and Knopf 1994). This system has fared worst of any tallgrass system due to its range coinciding with the most fertile farmland in the Midwest. In addition to loss through direct conversion to crop fields, farmland development has fragmented the natural landscape and has eliminated the large-scale processes of fire and grazing by native ungulates that were necessary to maintain this system. Lack of fire, grazing, or mowing results in a decrease in productivity due to the soil surface staying cooler and shaded longer in the spring (Rice and Parenti 1978, Hulbert 1988). Lack of fire allows tree cover to increase rapidly, especially on lower, more mesic slopes (Heineman and Bragg 1982). This system is well-adapted to moderate grazing over time or heavy grazing for short periods, but when used as long-term pasture and with high stocking rates, the dominant native grasses are reduced or eliminated. Heavy haying or grazing, or if those are done consistently during the mid-summer months, negatively affects the dominant warm-season grasses by removing their biomass before they have flowered. Cool-season grasses and forbs which set seed earlier are favored by these activities. Native and non-native forbs, woody species, and C3 grasses increase in the absence of fire, especially when combined with grazing by livestock. Drier sites on hilltops or rocky soils persist longer, but mesic sites on lower slopes can be invaded by trees and shrubs after just several years without fire. Non-native grasses have been planted for forage on some sites, as well. Restoration of full species diversity and soil characteristics is slow, even with active management (Kindscher and Tieszen 1998).

This system is found primarily in the Central Tallgrass Prairie (TNC Ecoregion 36) ranging from eastern Kansas and Nebraska to north-central Missouri and northwestern Indiana. In Missouri, it is attributed to EPA 47d, 47f, 72f.