Earthworm assemblages in the Eastern and Midwestern United States and the legacy of glaciation

Authors: MCCAY, TIMOTHY - Colgate University; ANDERSON, LAUREL - Ohio Wesleyan University; BLOCH, CHRISTOPHER - Bridgewater State University; CAHILL, ABIGAIL - Albion College; COOKE, SANDRA - Greensboro College; DOLAN, BENJAMIN - University Of Findlay; FLINN, KATHRYN - Baldwin Wallace University; GARNEAU, DANIELLE - State University Of New York (SUNY); HAINS, NATHANIEL - Northern Kentucky University; Scott, Drew; HOPFENSPERGER, KRISTY - Northern Kentucky University; KOLOZVARY, MARY BETH - Siena University; MANKIEWICZ, CAROL - Beloit College; SCANGA, SARA - Utica University; SCHAFER, JENNIFER - Winthrop University; SCHWARTZBERG, EZRA - Adirondack Research; SHEA, KATHLEEN - St Olaf College; SIMMONS, JEFFREY - Mount St Mary’s University; STYRSKY, JENNIFER - University Of Lynchburg

Submitted to: Biological Invasions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2026
Publication Date: 4/6/2026
Citation: Mccay, T.S., Anderson, L.J., Bloch, C.P., Cahill, A.E., Cooke, S.L., Dolan, B.J., Flinn, K.M., Garneau, D., Hains, N.J., Scott, D.A., Hopfensperger, K., Kolozvary, M., Mankiewicz, C., Scanga, S.E., Schafer, J.L., Schwartzberg, E., Shea, K.L., Simmons, J., Styrsky, J.N. 2026. Earthworm assemblages in the Eastern and Midwestern United States and the legacy of glaciation. Biological Invasions. 28:Article 91. https://doi.org/10.1007/s10530-026-03798-3.
DOI: https://doi.org/10.1007/s10530-026-03798-3

Interpretive Summary: Earthworm communities in North America consist of both native and non-native species. Past glaciation in eastern North America might have impacted earthworm abundance and diversity. Standardized surveys were used to evaluate factors influencing abundance and diversity of earthworms. Most earthworm biomass and earthworm species were in Midwest formerly glaciated areas and the least earthworm biomass and earthworm species were south of the glacier limit. Basic soils were also associated with more earthworm biomass and earthworm species. This research suggests foresters in the southern United States should manage for soil health assuming there will be little contributions from earthworms.

Technical Abstract: The earthworm fauna of North America consists of a dynamic pool of native and non-native species. History of glaciation during the Pleistocene may strongly affect present earthworm assemblages, but its importance relative to other factors is unclear. We used a standard sampling protocol at 94 sites across 13 states to better understand the factors affecting diversity and abundance of earthworms in the eastern and central United States. We divided our sites into Northeastern Glaciated, Midwestern Glaciated, and Non-glaciated regions. Habitat type, proximity to water and roads, soil type and drainage, and soil pH were measured. A small number of European species was dominant throughout the sampled region. Native earthworms were rare and pheretimoid (“jumping worm”) species were present only at a small portion of our sites. Earthworms were most abundant and diverse in the Midwestern Glaciated region, where non-native earthworm invasion was the most recent, and least common and diverse below the southern limit of glaciation. Soil pH had a subtle positive effect on earthworm abundance and diversity. Community composition differed among regions and habitats. Assemblages also differed between summer and fall/spring, probably due to seasonal sampling biases. Earthworm communities in previously glaciated areas, and especially in the recently invaded Upper Midwest, may benefit from soil organic matter accumulated during millenia without earthworms since glacial retreat.