Great Lakes Worm Watch

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Worm Research Studies around the Nation

Distribution and Invasion Patterns

Exotic Earthworm Invasion: integrated research and education to achieve natural resource protection on the Minnesota North Shore of Lake Superior

This 3 year project conducted a combination of visual indicator surveys and quantitative earthworm surveys 8 State Parks and 2 state waysides in the North Shore Highlands along Lake Superior. The primary objectives of the study wer to 1) provide broad distributional data (visual indicator surveys) on earthworm presence, absence and relative abundance in the major  forest types across the North Shore Highlands; 2) provide detailed assessments of the biomass and species assemblages of earthworm populations (quantitative earthworm surveys) in relation to the visual indicators used in the broader survey effort and in relation to the different forest types; and 3) provide public education, and opportunities for involvement, with respect to this project and the issue of invasive earthworms in general through park-based public programs and display posters, click here to see a poster display summarizing the project.

Location: Jay Cooke, Gooseberry Falls, Split Rock, Tettegouche, George Crosby Manitou, Temperance River, Cascade River and Judge Magney state parks; Caribou and Kadonce waysides
Lead Researcher:
Cindy Hale, Ph.D., Natural Resources Research Institute.

Changes In Hardwood Forest Understory Plant Communities In Response To European Earthworm Invasions

In the first 2 years of this study, the advancing leading edge of earthworm invasion moved about 10 meters into the forest and the associated changes in the forest are both numerous and dramatic. Total plant cover decreased from near 100% to less than 25%. The earthworm population increased nearly four fold across the advancing leading edge of invasion.

Location: Chippewa National Forest, MN.
Lead Researcher:
Cindy Hale, Ph.D., Natural Resources Research Institute.

Patterns of earthworm invasion and understory plant composition in lakeside northern hardwood forests.

This study surveyed understory plant communities, earthworms, soils, and tree composition in 314 plots located in 40 mature hardwood stands in the Chippewa and Chequamegon National Forests (Minnesota and Wisconsin, respectively). Stands were comparable in overstory composition, biomass, geology, and management history. In both regions the study found a correlation between the presence of exotic earthworms and the presence of cabins, resorts, boat landings, roads, and campsites. The results further support other studies showing that exotic earthworms significantly alter the structure and composition of northern hardwood forest understory plant communities and that the invasion is in an advanced but incomplete stage.

Location: Chippewa & Chequamegon National Forests
Lead Researcher:
Andy Holdsworth, MN Department of Natural Resources
Preliminary research results

Susceptibility of a Northern Hardwood Forest to Exotic Earthworm Invasion

This study sought to identify land-use factors in the Ottawa National Forest (ONF), Michigan (U.S.A.), that contribute to earthworm invasion in forest dominated by sugar maple (Acer saccharum Marsh.) so that the susceptibility to additional colonization could be evaluated. The study sampled earthworm communities in Sylvania Wilderness Area, a unique old-growth hardwood forest, and nonwilderness sites influenced by recreational fishing, recent timber harvesting, or roads. All the nonwilderness sites contained one to five species of exotic earthworms. In contrast, only 50% of wilderness sites contained exotic earthworms, all of a single species.

Location: Chippewa & Chequamegon & Nicollette National Forests
Michael Gundale, University of Montana - School of Forestry

Earthworms on Long Island

The purpose of this project was to determine what species of earthworms are
present on Long Island, where these species are located, and what type of environment they seem to prefer.

Location: Long Island, New York
Lead Researchers:
Lara Pomi & Marilyn Jordon, Stony Brook University
Full text - pdf

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