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Harvard Forest Symposium Abstract 2018

• Title: Garlic Mustard Management and Exotic Earthworms Affect Native Plant Diversity
• Primary Author: Michelle Jackson (University of Massachusetts - Amherst )
• Additional Authors: Erin Coates-Connor (University of Massachusetts - Amherst ); Karina Martinez (Not Specified); Kristina Stinson (University of Massachusetts - Amherst )
• Abstract:

  The invasive plant Alliaria petiolata (Garlic Mustard) can disturb aboveground diversity of native forest ecosystems in Massachusetts. Exotic earthworms have been hypothesized to promote A. petiolata invasion, but the mechanism of coinvasion is not understood, nor are the impacts of both species on native biodiversity. We conducted an eradication study at two sites in Massachusetts to test the responses of exotic earthworms and native plant communities to A. petiolata removal. This work was conducted at the Harvard Forest (central MA) and McLennan Reservation (western MA), where we established replicate plots without Garlic Mustard (control), reference plots with Garlic Mustard, and plots where Garlic Mustard was eradicated by hand one year earlier. We measured native plant diversity and earthworm biomass in the field from each treatment. Earthworm biomass was highest in the invaded treatment and declined to uninvaded levels in the garlic mustard eradication treatments. Results from a regression analysis demonstrated an interaction effect between eradication treatment and earthworm biomass on native plant diversity (p<0.05). Our findings suggest that A. petiolata populations may be facilitating earthworm invasion, contrary to previous studies suggesting the opposite relationship. Moreover, sites eradicated of Garlic Mustard had lower earthworm biomass than invaded sites, which posits this method as possible dual management strategy to control earthworm and Garlic Mustard invasions. We also show that native plant diversity is negatively correlated with earthworm biomass in invaded plots but positively so in eradicated plots, further supporting previous research that garlic mustard eradication as a tool can preserve aboveground diversity at least for some sites.

• Research Category: Invasive Plants, Pests & Pathogens
  Conservation and Management
  Biodiversity Studies