GRASSHOPPER (ORTHOPTERA, ACRIDIDAE) COMMUNITY COMPOSITION AND ECOLOGICAL DISTURBANCE ON SOUTHERN IDAHO RANGELAND

Grasshopper assemblages were examined at 30 sites in southcentral Idaho, representing various degrees and types of disturbance. These disturbances included heavy livestock grazing, wildfires, plowing, herbicide and applications, and seeding of introduced perennial bunchgrasses, mainly crested wheatgrass. These disturbances resulted in the loss of sagebrush and native perennial grasses and has led to the establishment of exotic annual grasses and forbs on several sites. Grasshopper assemblages on sites dominated by annual vegetation were characterized by relatively high densities, low species diversity, and high proportions of species with broad diet breadths. Introduced perennial grass seedings were characterized by a high proportion of grass-feeding grasshopper species and high species diversity. Sagebrush-grass sites were characterized by lower grasshopper density and high species diversity. These results obtained under generally low grasshopper densities, suggest that rehabilitation of annual grasslands with perennial grasses and shrubs, and protection of endemic plant communities, can contribute to more diverse grasshopper communities with lower proportions of pest species.