Effect of Invasive Earthworms On Leaf Litter Decomposition, Available Nutrients and Water Dynamics.

During the Wisconsian glaciation, native earthworms in the Northeastern United States were extirpated due the advancing ice sheets. European settlers introduced nonnative species and recently, species from Asia have established a foothold due to importation of goods. A greenhouse mesocosm study was conducted to evaluate the effect of L. terrestris (LT; European) and A. agrestis (AA; Asian) separately and together on the decomposition rate of Acer saccharum litter, soil/water chemistry and water dynamics. Results in this study indicated that LT increased litter decomposition rate, while AA did not.  Though separately the worms do not cause a significant difference in water loss, combined treatment LTAA shows increased evaporation and decreased leachate water volume significantly.  Leachate water chemistry suggests that treatments that include LT decrease Ca, P, S, Na, Si and Mg leaching losses. The differences in nutrients lost were mostly accounted for by the volume of water and not by concentration, similar to findings by others, suggesting long term soil chemistry changes. Several factors may have contributed to the differences between the effects of each species.   Evaluating the effects of different earthworm species is essential to understanding the ecological changes that may occur with invasion of a new area.