Earthworms

  • Common earthworm (Lumbricus terrestris)

Identification

All earthworms in Vermont are non-native. There are 19 species of earthworms known to occur throughout the state. Approximately 12,000 years ago the state of Vermont was covered by glacial ice. This event removed any native earthworms which may have evolved with our forests

Biology

Origin

Earthworms were inadvertently imported with soil and plant materials from Europe and Asia. They have continued to be imported purposefully as fishing bait and for use in gardens and composting.

Habitat

Some species live on the forest floor other live in the mineral layers of the soil.

Ecological Threat

  • Reduce forest floor organic matter
  • Relocate carbon lower in soil profile
  • Reduce herbaceous layer
  • Alter seed bed
  • Change forest habitat structure, possibly affecting salamanders and birds
  • Alter soil temperature, moisture, and water filtration

Management Options

Forest management planning should include strategies to minimize impacts on forest health. Avoid practices that spread earthworms into untreated soil or compost.  Not all forests have all species of earthworms, so minimizing the movement of soil from one location to another can reduce additional infestations. Nursery trees with root balls should be inspected before planting.

Be aware of signs that earthworms are present and affecting forest soils and forest health. Look for earthworm casts, diminished organic layer depth, or a forest devoid of understory plants. Forests near fishing areas may be especially vulnerable due to discarded earthworm bait.

Increase soil carbon by increasing the amount of organic matter on the forest floor.  Leaving branches on the forest floor after a harvest is one way to stock up on organic matter.

Consider promoting tree species with deep taproots, especially on sites with low organic matter or sandy soils.  Providing organic matter deeper in the soil may increase the amount of stable carbon for plant use.

Vermont Distribution

Found throughout the state.

Citations

Information Credit

Earthworms in Forests

Photo Credit

Joseph Berger, Bugwood.org