Early successional patterns of arthropod recolonization on reclaimed Wyoming strip mines: the grasshoppers (Orthoptera: Acrididae) and allied faunas (Orthoptera: Gryllacrididae, Tettigoniidae)

The colonization and community development of Orthoptera on a series of revegetated surface coal mines in Wyoming was examined. The fauna on an adjacent, undisturbed shrub-steppe site also was sampled. The reclaimed mines represented a series of sites ranging in age (after revegetation) from 0 to 6 yr. We found that the mine sites exhibited lower index values for species richness (R, 6-15), diversity H', 0.07-0.68) and evenness (J', 0.09-0.60) than the undisturbed site (R, 19; H', 0.79; J', 0.62). Community similarity indices (Bray-Curtis coefficients) indicated a low similarity between any mine site and the undisturbed shrub-steppe site. Cluster analysis revealed three major faunal assemblages on the mine sites that corresponded closely to vegetational changes: on two young sites dominated by annual forbs (greater than or equal to 34% cover) with little grass (less than or equal to 12% cover), there existed a depauperate fauna dominated by Ceuthophilus alpinus Scudder (Gryllacrididae); on one site with an even mix of forbs and grasses (33% and 21% cover, respectively), the Acrididae and Gryllacrididae were codominant; and on the four older sites dominated by grasses (greater than or equal to 38% cover, virtually no forbs), C. alpinus was again the dominant species, although substantial numbers of acridids were also present. Correlations of Orthoptera species richness and diversity with plant species richness and diversity produced significant positive relationships. The dominant grasshopper species on the mine sites are listed as "Economically Important Pest Species" by the USDA and may hinder successful establishment of young plants on reseeded minelands during periods favorable to grasshopper reproduction and survival. It is suggested, however, that, in the absence of significant grazing by native wildlife or livestock, these herbivorous and omnivorous insects provide an important ecological pathway for energy flow, litter decomposition, and nutrient cycling.