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Grantee Research Project Results

NCER Grantee Research Project Results

Biological Control And Impacts Of Garlic Mustard (Alliaria petiolata): Prospective Modeling, Invasion Facilitation, And Interactions With Native Communities

EPA Grant Number: F5F21821
Title: Biological Control And Impacts Of Garlic Mustard (Alliaria petiolata): Prospective Modeling, Invasion Facilitation, And Interactions With Native Communities
Investigators: Evans, Jeffrey A.
Institution: Michigan State University
EPA Project Officer: Just, Theodore J.
Project Period: January 1, 2006 through December 1, 2008
Project Amount: $99,572
RFA: STAR Graduate Fellowships (2005)
Research Category: Academic Fellowships

Description:

Objective:

Garlic mustard (Alliaria petiolata (Brassicaceae) (M. Bieb) Cavara and Grande) is a Eurasian biennial forb that is highly invasive in North America. Conventional control efforts against A. petiolata have been ineffective in all but the smallest infestations. A search for suitable biological control agents was initiated in 1998. Native plant abundance is often negatively correlated with A. petiolata abundance, but the underlying mechanisms driving this relationship are not well understood. In Michigan, exotic earthworms and large herds of white tailed deer may interact with A. petiolata and facilitate its spread and contribute to changes in native plant community composition. The first objective of this research is to use novel demographic population models to guide the selection of the most effective biological control agent(s) of North American A. petiolata populations across a range of habitat types. The second objective is to examine the relationship between A. petiolata, deer, and invasive earthworms and their individual and combined effects on native plant communities.

Approach:

Objective 1: Alliaria petiolata demographic data will be collected from eight sites across A. petiolata's core distribution in Michigan representing heterogeneous habitat types and invasion success. These data will be used to parameterize a matrix population model of A. petiolata biological control. Elasticity analysis of the matrix will be used to identify vulnerable transitions in A. petiolata’s life cycle and determine which of the potential agents, if any, are predicted to be most effective against Michigan populations.

Objective 2: At a high quality, species rich forest site I assigned 96 1 x 1 m sampling quadrats to three deer treatments (deer excluded, deer not excluded, sham fence) crossed with three A. petiolata treatments (plants pulled, plants unmanipulated, no plants present at beginning of study) according to a 3 x 3 factorial design. The goal of this project is to test for the effects of earthworm abundance and the presence or absence of A. petiolata and/or deer on the native plant community.

Expected Results:

Objective 1: This project will support selection of efficacious natural enemies for use against A. petiolata and will improve the overall safety of weed biocontrol by developing new agent selection methods that will help to decrease non-target impacts on other species.

Objective 2: Repeated surveys of the plant community, soil properties and earthworm abundance at the site will illuminate the impacts of earthworms and deer browse on A. petiolata and native species, of A. petiolata's impacts on native species, of interactions between A. petiolata and deer, and of the native community’s potential for recovery upon exclusion of either or both deer and A. petiolata.

Supplemental Keywords:

garlic mustard, deer, earthworms, biological control, invasive species, facilitation,, Ecosystem Protection/Environmental Exposure & Risk, Habitat, habitat dynamics, biological control agent, habitat disturbance, invasive plant species, garlic mustard, ecological consequences, invasive species, habitat restoration, habitat preservation

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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