There was a National Geographic Article about a year or so ago on Jamestown and in this one of the things that they pointed out was how much of a difference the Earth Worm has made to the forests. The article stated that pre European arrival the debris on the forest floor was so deep that it blew into drifts at time several feet deep. The arrival of the earth worms often in root balls of plants brought by settlers and other times as ballast for the ships has changed this depth and changed the growth of undergrowth especially. It was interesting to think that something as simple as a worm could have such an impact. It is possible years later that the Native Americans learned to use the worms to their benefit and possibly harnessed them to move blow downs.