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 (Co leoptera: Carabidae) fauna in an old-field community subjected to 11 y r 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 1 988 with either sewage sludge containing heavy, metal contaminants (Mi lorganite, Milwaukee, WI), uncontaminated urea-phosphate fertilizer, o r left untreated as controls. In 1989, manipulations designed to stimu late 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 w ith pitfall traps during 4 sample periods of 2 d each between May and September each year. Carabid abundance and diversity were significantl y higher in nutrient-enriched fertilizer and sludge plots, whereas rec overy 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 cupreo lata being most common and accounting for 85% of tile beetles collecte d. Species richness was not different between sludge (n = 18) and fert ilizer (n = 17) communities, whereas the control (n = 11) community co ntained significantly (P < 0.001) fewer species. Sludge plots had the most diverse carabid community (H' = 2.108) whereas tile 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. lucubland us accumulated cadmium, lead, and zinc, but at concentrations lower th an were present in the soil, indicating these species do not bioconcen trate heavy metals.