Ungulate - Prairie Dog - Plant Interactions in Badlands National Park

Fahnestock, Jace; Detling, James

"This report summarizes data collected during the first field season (May through August, 1995) of a multi-year project designed to evaluate the independent and interactive effects of bison and prairie dogs on plant species composition, plant biomass and nutrient dynamics, and soil nitrogen mineralization at selected sites in the BADL, South Dakota. This is being done by sampling vegetation and measuring soil nitrogen dynamics in five different herbivore treatments on and off three different prairie dog town sites. Data from this project will aid park personnel in their herbivore management efforts and a better understanding of the influence of ungulate herbivory on colony patches will assist management decisions regarding the current re-introduction of black-footed ferrets in the BADL. Five herbivore treatments were established during the fall and winter of 1994: off-colony with bison excluded, off-colony with continued bison utilization, on-colony with bison excluded but continued utilization by prairie dogs, on-colony with utilization by prairie dogs and bison, and on-colony with both herbivores excluded. Three spatially distinct prairie dog town sites were chosen that afforded sufficient space for exclosure construction, that had similar soil characteristics, and that had sufficient grassland space adjacent to prairie dog towns for the off-town treatments. Thus, there were three replicate sites for each of the five herbivore treatments. Aboveground biomass on off-town sites was more than two times greater than on-town sites. This was primarily due to the near elimination of grasses on prairie dog towns. Although plant cover was similar at all the sites, off-town sites were dominted by grasses while on-town sites were dominated by forbs. Plant species diversity was lower for off-town sites and exotic plants constituted a greater proportion of the biomass. Net nitrogen mineralization early in the growing season was four times greater on prairie dog colony sites, but all sites exhibited net immobilization by July. Enhanced nutrient supplies for on-colony sites resulted in lower C:N ratios in plant biomass." (from document Abstract)