Early Successional Patterns of Arthropod Recolonization on Reclaimed Strip Mines in Southwestern Wyoming: The Ground-dwelling Beetle Fauna (Coleoptera)

Abstract

The ground-dwelling beetle assemblages of seven reclaimed surface coal mines (revegetated at 1-yr intervals beginning in 1979) and an undisturbed area of sagebrush steppe vegetation near Kemmerer, Wyo., were sampled in 1983 using 25 pitfall traps per site. The three oldest sites (1977–79) received no topsoil during reclamation; the other four sites (1980–83) had stored topsoil respread on them before revegetation. The beetle assemblages were characterized by means of data on species richness and diversity, species dominance curves, and trophic-group structure. We found that initial recolonization and dominance was achieved by species that were either rare in the adjacent native vegetation, or had immigrated from other disturbed sites. Species richness and diversity showed an increase during the first 3 yr following revegetation, but then declined over the next 3 yr. The magnitude of the observed species richness and diversity trends may have been influenced by the presence or absence of topsoil on the sites. The number of herbivorous beetle species was positively correlated with the number of plant species present on the sites. The trophic structure on reclaimed mine sites was dominated by omnivores, insect-carrion feeders, predators, and fungivores, whereas the undisturbed site's beetle fauna was dominated by omnivores, predators, and herbivores. It seemed that the most successful colonists were omnivorous and scavenging species (that used seeds, weedy vegetation, and living and dead insects), and fungivores (that took advantage of fungi growing on dead organic matter in the respread topsoils). In view of the great dissimilarities that exist between undisturbed and reclaimed mine sites, even after 6 yr, we conclude that recovery of the mine lands will require a considerable length of time, and, due to the severity of the mining disturbance, may not ever yield a fauna and flora similar to those of the premining era.