Date of Award


Document Type

Honors Thesis (Open Access)


Colby College. Biology Dept.


Cathy Collins


Non-native earthworms are found throughout much of the United States and southern Canada in areas that were glaciated during the most recent glaciation. These earthworms are changing nutrient cycling, modifying soil structure, and influencing diversity in forests throughout the Northern United States, and their invasion northward is facilitated by human activities. Although worms are present in compost piles and gardens of all Maine counties, there are no comprehensive studies of earthworms distributions in forested areas of Maine. I documented the presence and absence of earthworms in forested recreation areas in Kennebec County, Maine, and investigated ecological and landscape level variables that may predict their presence or absence. To examine whether the presence of worms may alter forests they have invaded, I also measured environmental variables known to be affected by worms in forests with and without worms. I found earthworms at 12 out of 23 sites, and the single significant factor for predicting earthworm presence was the distance to roads: sample sites near roads were more likely to have earthworms. I also found that locations with worms have less litter and more phosphorous in the soil. My study is the first study to explore the distribution of earthworms in Kennebec County and my findings provide evidence that roads facilitate earthworm invasion, and that there are measurable differences in the soils where earthworms are present.


invasive earthworms, maine, non-native earthworms