Flint Hills tall grasslands

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Flint Hills, Kansas, USA. Source: John Charlton/Kansas Geological Survey

The Flint Hills tall grasslands covers the Flint Hills of Kansas and the Osage Plains of northeastern Oklahoma, in the USA. The Flint Hills tall grasslands is the smallest grassland ecoregion in North America. It can be distinguished from other grassland associations by the dominance of tallgrass species–and from the Central tall grasslands to the north by its more depauperate biota and a thin soil layer spread over distinct beds of limestone. These flinty beds of limestone, from which the name of this ecoregion is derived, rendered large areas unsuitable for corn or wheat farming. Today, the Flint Hills tall grasslands is an anomaly–an essentially unplowed (although heavily grazed) remnant of the tallgrass prairie. Historically, wildfire, drought and grazing by American Bison (Bison bison) and other ungulates were the principal drivers of habitat disturbance in this ecoregion. A new tallgrass prairie national park has been established covering about 44 km2. The Flint Hills ecoregion offers the best opportunity for restoration of tallgrass prairie in the USA.

caption WWF

Biological Distinctiveness

The Flint Hills and adjacent Osage Hills contain the last sizeable elements of tallgrass prairie on Earth. The Flint Hills is less rich in species than Big Bluestem (Andropogon gerardii), Old Switch Panic Grass (Panicum virgatum), and Yellow Indian Grass (Sorghastrum nutans). As in the case of other ecoregions of this section of North America, American Bison and Elk (Cervus elaphus) once roamed these tallgrass prairies, where they were hunted by the Wolf (Canis lupus). These species are now extirpated from the ecoregion, although American Bison are being reestablished here. Greater Prairie Chicken (Tympanuchus cupido) are relatively common on the Tallgrass Prairie Reserve.


There are a total of 317 vertebrate species found in the Flint Hills tall grasslands.


There are a number of amphibian taxa found in the ecoregion, namely: the American Toad (Anaxyrus americanus); Cope's Gray Treefrog (Hyla chrysoscelis); Gray Treefrog (Hyla versicolor), who in winter hibernates beneath surface litter; Great Plains Narrowmouth Toad (Gastrophryne olivacea); Great Plains Toad (Gastrophryne olivacea); Mudpuppy (Necturus maculosus), who inhabit weedy ponds and perennial streams; Northern Cricket Frog (Acris crepitans); Tiger Salamander (Ambystoma tigrinum); Plains Leopard Frog (Lithobates blairi); Plains Spadefoot (Spea bombifrons); Small-mouthed Salamander (Ambystoma texanum), whose breeding sites are ponds or other lotic waters; Spotted Chorus Frog (Pseudacris clarkii); Spotted Salamander (Ambystoma maculatum), a secretive species who spends most of its life underground or hiding beneath logs; Tiger Salamander (Ambystoma tigrinum); and Striped Chorus Frog (Pseudacris triseriata).


A considerable number of reptilian species occur in the Flint Hills tall grasslands ecoregion, including the following representative taxa: the Broad-headed Skink (Plestiodon laticeps); the Collared Lizard (Crotaphytus collaris); Common Musk Turtle (Sternotherus odoratus); Common Slider (Trachemys scripta); and Plain-bellied Water Snake (Nerodia erythrogaster), who hibernates underground or under rock piles.


A number of mammals inhabit the Flint Hills ecoregion, including the Black-tailed Prairie Dog (Cynomys ludovicianus); Franklin's Ground Squirrel (Spermophilus franklinii); the Endangered Indiana Bat (Myotis sodalis), who winters in caves and mines;


Notable bird species in the Flint Hills tall grasslands include the Near Threatened Black Rail (Laterallus jamaicensis); the Vulnerable Cerulean Warbler (Dendroica cerulea); the Near Threatened Chestnut-collared Longspur (Calcarius ornatus); and the Near Threatened Chimney Swift (Chaetura pelagica).

Conservation Status

caption Indian grass (Sorghastrum nutans). (Photograph by Mike Haddock)

Habitat Loss and Degradation

Much of the Flint Hills and the Osage Hills are in relatively intactThe condition of an ecological habitat being an undisturbed or natural environment ecological condition. Although heavily grazed by livestock in some places, a number of common native  plant species remain extant.

Remaining Blocks of Intact Habitat

This unit contains the largest blocks of relatively intactThe condition of an ecological habitat being an undisturbed or natural environment tallgrass prairie among the three tallgrass units and some of the largest blocks in all of the Great Plains ecoregions.

Several important blocks of habitat in this ecoregion include:

  • The Barnard Ranch (The Nature Conservancy-owned ranch in the Osage Hills), northeastern Oklahoma
  • Tallgrass Prairie National Preserve, Flint Hills region, central Kansas - approximately 44 km2
  • Konza Prairie, northeastern Kansas (key research site for the tallgrass prairie ecosystem) - 34.8 km2

Degree of Fragmentation

Habitat fragmentation is relatively low considering existing land uses and level of livestock grazing within the ecoregion.

Degree of Protection

Creation of the Tallgrass Prairie National Park in 1996 has added to the amount of habitat protected in this unit. The Nature Conservancy has also established a sizeable conservation unit in the Osage Hills: the Barnard Ranch. The Konza Prairie is a small protected area preserve, owned by The Nature Conservancy and Kansas State University.

Types and Severity of Threats

Because this ecoregion is too difficult to farm, future threats of conversion to agriculture remain low relative to other grassland ecoregions. Grazing could become a more severe threat if not properly managed. Some rangeland has been converted to non-native cool-season grass. There is increasing habitat fragmentation due to smaller homestead units being divided from large ranch holdings.

Suite of Priority Activities to Enhance Biodiversity Conservation

  • Working with appropriate agencies, efforts should be made to increase protection of the Flint and Osage hills.
  • Additional activities of high priority are to reconnect and restore the remaining blocks of habitat. This will be an uphill effort in most areas and perhaps futile in others. The extent of habitat conversion of this ecoregion is discouraging, and support for conservation is weak in parts of this unit.
  • It is important to alter range practices to manage for biodiversity value rather than maximum beef production. Inherent in this strategy is the elimination of below market lease rates on public lands.

Conservation Partners

  • Clinton Owensby, authority on the Tallgrass prairie
  • Kansas Natural Heritage Inventory
  • The Nature Conservancy, Tallgrass Prairie Office
  • U.S. Fish and Wildlife Service

Relationship to other classification schemes

Tallgrass prairie is derived from Sims. It corresponds to Omernik ecoregion 28 (Flint Hills) and Bailey section 251F (Flint Hills).


  • J.M.Hoekstra, Molnar, J. L.; Jennings, M.; Revenga, C.; Spalding, M. D.; Boucher, T. M.; Robertson, J. C.; Heibel, T. J. et al. (2010). Molnar, J. L., ed. The Atlas of Global Conservation: Changes, Challenges, and Opportunities to Make a Difference. University of California Press. ISBN 978-0-520-26256
  • Charles Kappler (Ed.). Part III.—Acts of Fifty–ninth Congress—First Session. (1906) Chapter 3572, June 28, 1906 [H.R. 15333] - [Public, No. 321] 34 Stat., 539  An act for the division of the lands and funds of the Osage Indians etc. Indian Affairs: Laws and Treaties. Washington DC: U.S.Government Printing Office, 1913. 3:252-258
  • Les Warehime (2000) History of Ranching the Osage. Tulsa, Oklahoma: W.W. Publishing. p. 253.
  • R.G. Hamilton (2007). Restoring heterogeneity on the Tallgrass Prairie Preserve: applying the fire–grazing interaction model. Pages 163–169 in R.E. Masters and K.E.M. Galley (eds.). Proceedings of the 23rd Tall Timbers Fire Ecology Conference: Fire in Grassland and Shrubland Ecosystems. Tall Timbers Research Station, Tallahassee, Florida, USA.

Disclaimer: This article contains some information that was originally published by the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth have edited its content and added new information. The use of information from the World Wildlife Fund should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.




Fund, W., & Hogan, C. (2014). Flint Hills tall grasslands. Retrieved from


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