The effects of bison grazing and fire on tall grass prairie heterogeneity

Historically, before European settlement, Bison bison and fire played a key role in the structure and function of prairie grasslands. Bison also played a key role to the survival and success of many tribes of the Great Plains. Since we know bison tend to forage on recently burned areas, fire may have been a very important tool of the Native Americans of the past. Oral history among certain tribes of the Plains, suggests they intentionally started fires for agricultural reasons, range management, and to attract bison. It is said the Lakota, used fires to guide bison to bison jumps. In addition, the Mandan and Hidatsa were said to have lit yearly spring fires to benefit the land and quite possibly to attract bison. Lightning strikes that would start fires were a fairly common natural phenomenon as well. Whether it was intentional, inadvertent, or natural, fire was an important factor to the prairie grassland ecosystem processes. The long history of fire and bison suggests that together, they played a critical role to the structure and function of grasslands and a precursor to habitat heterogeneity. This project investigated the creation and significance of habitat heterogeneity as a consequence of fire-grazing interactions in the Flint Hills tall grass prairie of the Konza Prairie LTER in an effort to examine how Native Americans may have historically managed rangelands, and to look at best practices to manage bison herds today in an effort to maintain grassland heterogeneity. Results indicated that in the 1, 2, and 4-year grazed/burned watersheds were significantly higher in % of heterogeneity then the ungrazed/burned watershed. The 1, 2, and 4-year ungrazed/burned watersheds tended to be more homogenous; a more uniform type of vegetation was present. While both 20-year burns appeared very heterogeneous, this was mostly a result of woody vegetation encroachment.