Abstract - The Role of Prairie Dogs (Cynomys ludovicianus) and Bison (Bison bison) in Determining the Abundance and Species Composition of Grasshoppers in Wind Cave National Park
Redak, Richard A., Detling, James K. and Capinera, John L.. The Role of Prairie Dogs (Cynomys ludovicianus) and Bison (Bison bison) in Determining the Abundance and Species Composition of Grasshoppers in Wind Cave National Park.
Previous research into the interactions between plants and their herbivores at Wind Cave National Park (WCNP) has focused primarily upon the relationships between mammalian herbivores and their forage plants (Coppock et al. 1980, Coppock 1981, Coppock et al. 1983a and b, Koford 1958, McHugh 1958). Coppock et al. (1983a) showed that extensive prairie dog (Cynomys ludovicianus) grazing is capable of reducing graminoid biomass, locally changing plant species composition (selecting for increased forb and shrub biomass and forb diversity), enhancing plant nitrogen content and increasing forage digestibility. Additionally, it has been shown that bison (Bison bison) preferentially graze on young prairie dog towns. Presumably, this preferential grazing is due to prairie dog induced changes in vegetation structure, species composition, and forage quality. These prairie dog-bison-plant interactions create three distinct vegetational zones within a prairie dog town. The first, old dog town, is comprised predominantly of Artemisia frigida and usually has been colonized by prairie dogs for more than 8 years. The second state of colonization, young dog town, is frequently comprised of Poa spp., Agropyron smithii, Stipa spp., Bouteloua spp., and Andropogon spp. and various forbs. Young dog town plant species typically have been noticeably grazed, and such areas have been colonized by prairie dogs from 0 to 8 years. The third state of colonization, off dog town, is comprised predominantly of Poa spp., Agropyron smithii, Stipa spp., Bouteloua spp., and Andropogon spp. Off dog town plant species usually have only been lightly grazed (if at all), and these areas have not been colonized by prairie dogs.
With the exception of soil nematodes, little research at WCNP has been conducted investigating the role invertebrates may play in the biotic communities comprising prairie dog towns. Due to their damage and the costs associated with control, grasshoppers may be the most important insect herbivore of rangleand in North America. Therefore, the objectives of this project are to determine if the state of dog town colonization (resulting from prairie dog-bison-plant interactions) affects (1) grasshopper densities; (2) grasshopper species composition and (3) type of grasshopper feeding strategy (graminivorous, forbivorous, oligophagous or polyphagous).