Abstract - Impacts of Black-Tailed Prairie Dogs on Vegetation in Wind Cave National Park

Coppock, David Layne. 1981. Impacts of Black-Tailed Prairie Dogs on Vegetation in Wind Cave National Park. M.S. Thesis. Colorado State University, Ft. Collins, CO. 86 p.

Abstract

Studies were conducted in the mixed-grass prairie of Wind Cave National Park, South Dakota, to examine the effects of different durations of prairie dog (Cynomys ludovicianus) impact on plant standing crops, composition, species diversity, and nitrogen concentration. Impacts of prairie dogs decreased peak standing-crops of total (live plus standing dead) vegetation at the initially modified edges of dog towns and in the older core areas of dog towns compared to adjacent off-town prairie. Changes in the overall composition of vegetation relative to uncolonized prairie were only evident in the core areas of dog towns, however, where the biomass ratios of graminoids:forbs were greatly decreased. Increasing duration of prairie dog impact progressively reduced the litter (mulch) layer and progressively increased the proportion of total live vegetation (relative to standing dead) in the community compared to off-town prairie. Plants collected from prairie dog towns clearly had increased nitrogen concentrations compared to plants collected from adjacent, off-town sites.

Impacts in the core areas of prairie dog towns greatly altered plant species composition compared to off-town prairie by reducing the abundance of climax graminoids, which in turn facilitated the establishment of annual forbs. The only clear effect of prairie dogs on plant species diversity was observed in an Andropogon community where moderate duration (3-8 years) of prairie dog occupation clearly increased plant species diversity compared to off-town prairie and the older center of the dog town.

The distribution of prairie dogs within colonies indicated that colony edges with off-town prairie supported the greatest densities of animals. This suggested that impacts of prairie dogs eventually became severe enough to negatively influence the abundance of prairie dogs in colony core areas.