Tall-grass upland prairies once covered much of the eastern Great Plains and stretched from southern Manitoba down to east Texas where they converged with the Texas-Louisiana coastal tall-grass prairie. Upland prairies are distinct from coastal prairies in total precipitation rates and underlying soil types. Upland tall-grass prairies receive about 71 cm (28 inches) of annual rainfall and typically have rich, deep, well-drained soils. This makes the upland tall-grass prairie lands ideal for conversion to agricultural lands. As a result, upland tall-grass prairies now mostly exist as patchy fragments on federal lands or preserves, with less than 3 million acres (4%) of this habitat remaining.

The Tallgrass Prairie Preserve is located in Osage County, Oklahoma, at the southern end of the Flint Hills ecoregion. The Flint Hills ecoregion is atypical of the Great Plains, in that the rolling grasslands are underlain with rocky soils featuring shallow, limestone outcroppings. The poor quality of these soils for agricultural use is the primary reason that this comparatively large prairie remnant remains mostly untouched by man. The Tallgrass Prairie Preserve is at the southern end of an intact tall-grass prairie ecosystem that stretches over 50 miles wide, from Northern Oklahoma up to the border of Kansas and Nebraska, covering the entire eastern one-third of Kansas. The preserve, owned and managed by The Nature Conservancy, extends over 45,000 acres and represents the largest protected remnant of native tall-grass prairie in the world. .

The Tallgrass Prairie Preserve in Osage County, OK [Photo: Harvey Payne, Tallgrass Prairie Preserve]

Management
Each year about one-third of the preserve is burned in a controlled burn regimen called "patch burning". In addition to prescribed burns, the biodiversity of the prairie is maintained through grazing by the 2500 head of bison that live on the preserve.

Biodiversity on the Preserve
Burning and grazing management help promote biodiversity of the tall-grass prairie community. In addition to the prairie grasses and forbs, the Tallgrass Prairie Preserve is home to 23 species of fish, 55 species of reptiles and amphibians, 212 species of birds and 41 species of mammals, including threatened and endangered species such as the western prairie fringed orchid (Platanthera praeclara) and the mountain lion (Puma concolor). Additionally, the preserve has 168 moth and 92 butterfly species serving as important pollinators for prairie plant life.

Threats to the Preserve and to Upland Prairies
The Nature Conservancy has identified invasive species such as sericea lespedeza (Lespedeza cuneata) and eastern red cedar (Juniperus virginiana) as important threats to the biodiversity of the Tallgrass Prairie Preserve. They have combated these species through controlled burns and sustainable grazing management. Tall-grass prairies, in general, and the areas surrounding the preserve, more specifically, are threatened by poor land management and habitat fragmentation.