2005 BES Annual Meeting Presentation and Poster Abstracts
Invasive Soil Invertebrates and N-Cycling
Katalin Szlavecz, Katarina Juhaszova and Peter Groffman
Abstract: Invasive species often dominate urban soils and can profoundly affect the functioning of ecosystems. In this study we compared the influence of three earthworm and six isopod species on soil inorganic N pools and nitrification rates. We conducted laboratory feeding experiments using commercially available topsoil, and oak, tulip poplar and beech litter as food. At the end of the three weeks the animals were removed, and inorganic N pools and – after three week microbial incubation - potential nitrification and N-mineralization rates were measured. Total inorganic N was highest in the soil (both field and lab) inhabited by Amynthas, an Asian exotic earthworm. Ammonium made up more than 90% of soil inhabited by Eisenoides, the native earthworm. All three species altered nitrification rates compared to controls. Again, Amythas had the largest impact, while there was no difference between Eisenoides and the European Lumbricus. In contrast, incubation experiments with all six isopods resulted in net immobilization. The overall effect was the same, but the rates were different among the species. Our results point to strong species effects, especially among earthworms, which has to be taken into account when different microhabitats are invaded by different species.