Bison use of fire-managed remnant prairies

This study was designed to: 1) compare the landscape distribution patterns of bison on fire-managed prairie remnants in the tallgrass (Oklahoma), and mixed prairie (Nebraska); and 2) identify the extent to which fire and range site [topoedaphic classification of the landscape] affect bison distribution patterns. This research was conducted at 2 sites: the Niobrara Valley Preserve (1990-1996), and the Tallgrass Prairie Preserve (1993-1996). At both preserves, bison selected burned areas during the growing season for 1-3 years and mostly avoided old burns and unburned areas. There was an interaction between fire and range site in selection patterns. In the absence of fire, bison mostly avoided both the Choppy Sand range sites at the Niobrara Valley Preserve and Loamy Prairie range sites at the Tallgrass Prairie Preserve. When they were burned, however, these sites were highly selected. The main difference in bison selection patterns between the Tallgrass Prairie Preserve and the Niobrara Valley Preserve was observed during the dormant season. In the Tallgrass Prairie Preserve, burned sites continue to be preferred during the dormant period for an average of 2 years while in the Niobrara Valley Preserve selections mere random. These differences can be explained by 2 mechanisms: the fall and winter re-growth of forage at the more southern latitude and the significant physiognomic changes that fire can cause in tall grass prairies. Our study documents a continuing interaction between the ecological processes of the fire regime and bison distribution and abundance within 2 of the major prairie landscapes of the Great Plains, and provides critical details for understanding this relationship.