Study
Non-native invasive earthworms as agents of change in northern temperate forests
Bohlen, Patrick J.; Scheu, Stefan; Hale, Cindy M.; McLean, Mary Ann; Migge, Sonja; Groffman, Peter M.
Frontiers in Ecology and the Environment, 2004
Reviews measurements taken across earthworm invasion fronts in northern temperate forests that had no earthworms since glaciation, comparing soil structure, forest floor organic layers, nutrient cycling and plant communities on invaded and uninvaded sides.
- Studied in
- Lumbricidae, Plantae
- Sample size
- review of invasion fronts and their measured effects
Invasion consumes the forest floor organic layer within a few years, alters soil structure and nutrient cycling, reduces the abundance of native understorey plants and tree seedlings, and changes soil invertebrate communities.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Introduced earthworms act as ecosystem engineers whose effects on previously earthworm-free forests are substantial and largely detrimental to native communities.
How NatureHQ reads it
The reason "earthworms are good for soil" cannot be stated without saying where. In a garden or an arable field, earthworm activity improves the things a gardener values. In a forest that has had no earthworms since the ice retreated, the same activity removes the deep leaf layer that the understorey depends on. The animal is doing the same thing in both places; what differs is what was there before, and this is as clean a case of context deciding a verdict as the corpus holds.
- A review across systems that differ in soil, climate and invading species.
- Invasion fronts move, so the comparison is partly between places at different stages rather than between fixed conditions.
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Earthworms
In a garden, earthworms improve the soil. In a northern forest that has had none since the ice retreated, the same worms eat the leaf layer the understorey depends on. Same animal, same behaviour, opposite verdict.
Invasive species
Most species that arrive somewhere new fail. Most that establish do nothing measurable. A minority spread and cause serious harm — and origin alone does not predict which is which.
Published by: Wiley journalsPublished in a Wiley journal.
doi.org/10.1890/1540-9295(2004)002[0427:nieaao]2.0.co;2
Checked against Crossref on 2026-09-28, and they agree on the title, the authors and the year.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-09-04.