Influence of sewage sludge and fertilizer on the ground beetle (Coleoptera: Carabidae) fauna of an old-field community

The abundance, species richness and diversity of die ground beetle (Coleoptera: Carabidae) fauna in an old-field community subjected to 11 yr of nutrient enrichment were examined during 1991 and 1992. The site near Oxford, OH, consisted of six 0.1-ha plots treated. from 1978 to 1988 with either sewage sludge containing heavy, metal contaminants (Milorganite, Milwaukee, WI), uncontaminated urea-phosphate fertilizer, or left untreated as controls. In 1989, manipulations designed to stimulate recovery were initiated using various combinations of liming (to account for decreased soil pH in nutrient enriched plots) and tilling within each treatment. Ground beetles were sampled from each subplot with pitfall traps during 4 sample periods of 2 d each between May and September each year. Carabid abundance and diversity were significantly higher in nutrient-enriched fertilizer and sludge plots, whereas recovery manipulations of liming and tilling had no effect. In total, 24 carabid species were collected, with Harpalus pensylvanicus, Calathus opaculus, Amara impuncticollis, Poecilus lucublandus, and Amara cupreolata being most common and accounting for 85% of the beetles collected. Species richness was not different between sludge (n = 18) and fertilizer (n = 17) communities, whereas the control (n = 11) community contained significantly (P < 0.001) fewer species. Sludge plots had the most diverse carabid community (H' = 2.108) whereas the control plot was die least diverse (H' = 1.744). Fertilizer plots were dominated by N. pensylvanicus (42% of beetles) yet were still more diverse (H' = 1.849) than control communities. Both H. pensylvanicus and P. lucublandus accumulated cadmium, lead, and zinc, but at concentrations lower than were present in the soil, indicating these species do not bioconcentrate heavy metals.