Mk Neal wrote:Much of North America was not home to earthworms before European settlement. Particularly here in the Great Lakes region the forests evolved without such worms.
Yes - the boreal forest is also included in this.
During the last glaciation (10,000 years ago) they were essentially removed from much of the continent.
I assisted in some invasive earthworm research a while back - it was more rewarding than you may think..... Essentially the worms are spreading where we transport them (primarily along roads). In our sampling it was fairly obvious once you got your hands into the soil whether or not we were going to find evidence of earthworms. They are very good (bad) at turning through the top layers of soil and disturbing the leaf-litter layer.
I'm not up to date on the research, but it is out there to be found.
Perhaps earthworms are an example of a species whose presence we assume means good things, but of
course in the right context we see that it may not be so.