Eurasian earthworms are a growing concern to forests in northern regions of the United States and Canada. Earthworm invasion alters nutrient retention and uptake in ecosystems and reorganizes plant and animal community structure and composition. Likewise, garlic mustard (Alliaria petiolata) invasion alters native plant communities. Many studies have examined the positive relationship that may exist between invasive shrubs and Eurasian earthworms; however, very few have examined the interactions between garlic mustard and Eurasian earthworms. Our goal is to characterize the relationship between garlic mustard and Eurasian earthworm species in southwest Ohio forest understories. Earthworms were sampled by liquid mustard extraction. Earthworm community composition, abundance and biomass were compared between 0.1 m2 plots consisting of garlic mustard, cut-leaved toothwort (Cardamine concatenate), or wild ginger (Asarum canadense).
Results/Conclusions
One-way ANOVA did not indicate a difference in average abundance of Eurasian earthworms among plots with the three plant species. We did find a greater abundance of juvenile earthworms than adults in the spring than the fall sampling period. One-way ANOVA indicated a greater mean Eurasian earthworm dry weight biomass in garlic mustard and ginger plots than in cut-leaved toothwort plots in the spring, and a slightly greater mean Eurasian earthworm biomass in ginger plots than garlic mustard plots in the fall. Nightcrawlers (Lumbricus spp.) have a greater mean biomass than all other worm species sampled in all sampling periods. Linear regression does not show a correlation between aboveground % cover of plants and earthworm abundance or biomass. Analysis of similarity did not identify distinct worm communities beneath garlic mustard, cut-leaved toothwort, or ginger. Our results do not support strong feedbacks between garlic mustard and Eurasian earthworms.