Variation in Grasshopper (Acrididae) Densities in Response to Fire Frequency and Bison Grazing in Tallgrass Prairie

While weather can contribute signiÞcantly to grasshopper population dynamics in North American grasslands, local environmental conditions resulting from land use practices may be equally important. In this study, signiÞcant differences in grasshopper density were detected among adjacent watersheds from Kansas Flint Hills tallgrass prairie that differed in Þre frequency and especially bison grazing treatments. Grasshopper densities were 2.5 times greater in grazed watersheds compared with ungrazed ones. Grasshopper densities also varied somewhat in response to Þre frequency, mostly in species-speciÞc ways. No treatment interactions on overall grasshopper density weredetected. Theeffects of Þre frequency andbison grazingwere implemented inpart through their combined effect on the structural heterogeneity of vegetation, and other habitat characteristics. Individual grasshopper species responded uniquely to combinations of Þre frequency and bison grazing. Grazing resulted in signiÞcant increases in density for seven of the nine most abundant species; Þre frequency affected two species; and one species did not respond to either Þre or grazing. Understanding effects of habitat on grasshopper densities provides opportunities to manage these populations for economic or conservation needs.