Do Invasive Earthworms Affect the Functional Traits of Native Plants?

Area of Science:

• Ecology
• Invasive Species Biology
• Plant Science

Background:

• Invasive earthworms are significant drivers of plant community shifts in North American forests lacking native earthworms.
• Earthworm impacts on plant reproduction, recruitment, and development are potential mechanisms for these community changes.
• Limited research exists on functional trait responses of native plants to earthworm invasion.

Purpose of the Study:

• To investigate the effects of invasive earthworms on the functional traits of native North American forest plant communities.
• To understand the mechanisms underlying earthworm-induced plant community changes by examining trait responses.

Main Methods:

• A mesocosm (Ecotron) experiment was conducted using a plant community of two herb and two grass species.
• Two earthworm treatments (presence vs. absence) were applied to the plant communities.
• Above- and belowground plant biomass and functional traits were measured after a 3-month experimental period.

Main Results:

• Earthworm presence did not significantly alter overall plant community biomass or cover.
• Only four out of fifteen measured above- and belowground functional traits were significantly affected by earthworms.
• Species-specific trait responses were observed, with grasses showing more pronounced changes in leaf traits than herbs.

Conclusions:

• Invasive earthworms can induce species-specific changes in plant functional traits, particularly those related to resource uptake.
• These trait alterations may modify plant competition dynamics over time, contributing to observed community shifts in invaded ecosystems.
• Further research is needed to fully elucidate the long-term consequences of earthworm invasion on forest plant communities.