The effect of urban ground covers on arthropods: An experiment

Changes to the ground layer in urban areas are extensive, but the effects on arthropod fauna are poorly understood. We undertook a manipulative experiment to examine the response of arthropods to small-scale variation in ground covers commonly found in urban parks and gardens in Australia. The ground covers tested were bare ground, leaf litter, woodchips and grass, with plot sizes of 3.6 m². Epigeic arthropods were sampled with pitfall traps and Tullgren funnels over 12 months following establishment of the treatments. All epigeic arthropods were sorted to order and the ants (Hymenoptera: Formicidae), beetles (Coleoptera), millipedes (Diplopoda) and slaters (Isopoda: Oniscidea) were examined at lower taxonomic levels. Diverse arthropods rapidly colonised previously cleared plots in all four treatments and were most abundant in grass plots. The diversity of ants and beetles was significantly different in different ground covers and tended to be most diverse in grass plots. Despite the treatments providing very different microclimates, the fauna studied did not show strong selection for a particular cover type overall. The abundance of grass cover in the surrounding area may have led to the grass plots having the greatest abundance of arthropods. These results have important implications for developing effective small-scale conservation efforts for arthropods in anthropogenically modified landscapes, especially for species with poor dispersal abilities.