Earthworm Invasion: Studying the Coupled Human and Natural Systems of Human Mobility and Earthworms in Minnesota

Lee Frelich, University of Minnesota
Evan Roberts, University of Minnesota
Bryan Runck, University of Minnesota
David Van Riper, Minnesota Population Center
Kyungsoo Yoo, University of Minnesota

Earthworms can move, at a maximum, 5-10 metres in a year. Any long distance migration of earthworms relies on human help, and it has been substantial. Until the late nineteenth century there were no earthworms in the state of Minnesota, but worms are now present in much of the state. Although their impact as an invasive species has been subtle, it can also be substantial with reductions in the presence of ground nesting birds, and impact on the fruits consumed by black bears. The potential impact on the boreal forests of northern Minnesota, where earthworms are still uncommon, is likely to be greater than on the prairie and in woodlands. Genetic similarities between the earthworms that have invaded Minnesota, and those that have invaded similar biomes in Scandinavia suggest a possible link between Scandinavian migration and earthworm invasion. To further understand the coupled history of earthworms and humans in Minnesota, we are conducting a case study of three Minnesota townships. Using a variety of methods, including archival research, soil sample testing to measure the presence of earthworms, reconstitution of the household and individual structure of the communities. We selected our three communities — Bigelow, Borgholm, and Canosia — purposively to represent three different biomes in the state, and to include different vectors by which humans may have brought earthworms into particular sections of the township. Our research suggests that agriculture and recreation are important vectors of earthworm invasion, while logging is likely to have been less important.

No extended abstract or paper available

 Presented in Session 190. Environmental site selection in America