UW-Platteville faculty, students to study earthworms

March 11, 2011

PLATTEVILLE - Evan Larson, University of Wisconsin-Platteville assistant professor of geography, in partnership with the College of Menominee Nation in Keshena, has received a Wisconsin Alliance for Minority Participation grant to study the ecological effects of invasive earthworm species in the Menominee Forest. The project, set to begin in May, will include two students each from UW-Platteville and CMN, who will assist in surveying invasion fronts, taking samples and documenting changes in the forest floor plant communities.

The Menominee Forest, one of the oldest sustainable forests in the world, contains 12 habitat types and 30 different species of trees, making it an ideal laboratory, Larson said. He added that he was pleased to receive permission to perform research on the Menominee Reservation. "It's their land and their forest, so I appreciate that they are letting me do work there," he said. "They are pretty excited to see what we find."

Larson, who began his invasive earthworm research as a graduate student at the University of Minnesota, said that it is important to understand how earthworms impact forest renewal and regeneration in order to come to an understanding of how forests may change in the future in response to these invasive species.

"The earthworms that most people are familiar with, including angleworms and night crawlers, are not native to the Great Lakes region of North America," Larson said. "These and several other species were introduced to this continent in the flowerpots and ship ballast of the earliest European settlers."

Larson added that since their arrival, the earthworms have slowly been moving out from human environments, sometimes at their own pace of five to 10 meters per year, and at other times rapidly in the bait containers of countless fishermen and women. He explained further that the earthworms' presence, while beneficial in agricultural settings, can have disastrous effects on native forest communities.

"These research findings will not only benefit the Menominee Nation, but also Southwest Wisconsin," Larson said. "We have the state parks and the Platte, Sinsinawa and Belmont mounds, which are all forested, but because the forests cover a less extensive area, it actually magnifies the importance of this research for our area."

Once earthworms invade a forest, Larson said they begin to change the composition and hydrology of the forest site, accelerating nutrient cycling and leaching, effectively eliminating the seedbed for native plants.

Of particular concern for the people of Wisconsin, Larson said that his research found that the arrival of earthworms into sugar maple forests actually increases the susceptibility of those trees to drought. "For a sugar maple, which is already drought sensitive, earthworms could accelerate the loss of the species under some climate change projections," he said.

Larson added that while hiking through a forest it is relatively clear where earthworms have been and where they have not. "When you go from a leaf bed to a dirt floor, you are likely standing right on an earthworm invasion front," he said, adding that the presence of vermicasts, the organic matter they have broken down, are telltale signs of them.

UW-Platteville also partners with CMN through a grant from the Tribal Colleges and Universities Program that is funded through the National Science Foundation to help bring American Indian students to larger universities, allowing them to become more active in the science, technology, engineering and mathematics programs on campus.

Contact: Evan Larson, assistant professor, UW-Platteville Department of Social Sciences, (608) 342-6139,larsonev@uwplatt.edu

Written by: Barbara Weinbrenner, communications specialist, UW-Platteville College of Liberal Arts and Education, (608) 342-6191, weinbreb@uwplatt.edu


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