Great Basin Naturalist


The population dynamics of litter and foliage arthropods in undisturbed and intensively managed sagebrush (Artemisia tridentata) and bitterbrush (Purshia tridentata) habitats in southeastern Wyoming were assessed bv the measurement of density and the determination of indices of diversity, richness, and evenness. Brush management consisted of either mowing to a 20-cm stubble or applying the herbicide 2,4-D butyl ester. A total of 63 arthropod species were found in foliage and 150 species in litter. Mowing and herbicide applications resulted in significant changes in the density of 16 of the 46 major arthropod foliage species and 56 of the 70 major litter species. Diversity increased, except in Hymenoptera and Coleoptera, in both mowed and herbicide-treated foliage. In foliage, richness generally increased in all orders following mowing, and evenness tracked diversity. In litter, the diversity of Coleoptera decreased following mowing and herbicide application in Collembola, Homoptera, and Diptera. Evenness followed diversity in trends in both treatments. Soil arthropods were absent in this habitat before and after treatments.