Invertebrate diversity in newly established mulch habitats in a Midwestern urban landscape

The invertebrate fauna in artificial urban habitats has yet to be systematically investigated. The current field study in central Ohio was undertaken to assess the numbers and types of macroinvertebrates in mulched and unmulched plots during a one-year period. Invertebrates quickly infiltrated the plots with bare soil (control) and any of four types of mulch (shredded hardwood, shredded recycled wood, pine bark mini-nuggets, and pea gravel). One month after establishing the plots, invertebrates were present in numbers comparable to subsequent months. Invertebrates found in the plots were primarily saprophytic taxa: millipedes (32.6%), segmented worms (19.8%), isopods (6.7%), and various beetle families (1.5%). Predatory taxa included centipedes (9.8%), ants (9.7%), carabid beetles and staphylinid beetles (7.3%), and spiders (0.9%). Types of invertebrates were similar in all ground cover types, but numbers of invertebrates differed significantly. Invertebrates were present year-round in mulched plots, and plots with organic mulch harbored significantly more invertebrates than plots mulched with pea gravel. Bare soil always contained the fewest number of invertebrates. There was no significant difference in numbers of invertebrates based on the cardinal side of the building.