Ask anyone on the street if earthworms are good for ecosystems and you will undoubtedly receive a resounding “YES!”. When asked why, they may say something like “earthworms mix and aerate the soil”. It is a basic ecological concept that we may have learned as early as kindergarten. However, recent research on invasion of these seemingly benevolent creatures into previously earthworm-free hardwood forests of the Great Lakes Region has seriously challenged that belief. Researchers at the University of Minnesota, and elsewhere, have documented dramatic changes in native hardwood forest ecosystems when exotic earthworms invade. These changes including losses of native understory plant species and tree seedlings, changes in soil structure and declines in nutrient availability. There is also fascinating evidence emerging that the changes caused by exotic earthworms may lead to a cascade of other changes in the forest that affect small mammal, bird and amphibian populations, increase the impacts of herbivores like white-tailed deer, and facilitate invasions of other exotic species such as European slugs and exotic plants like buckthorn and garlic mustard. These results suggest that exotic earthworms may pose a grave threaten the biodiversity and long term stability of hardwood forest ecosystems in the region. Much more research is needed.
So, which earthworms are native in the Great Lakes Region? None!
Read more... http://www.nrri.umn.edu/worms/forest/index.html