Jocelyn Tsai

THE LONG TERM EFFECTS OF GARLIC MUSTARD (ALLIARIA PETIOLATA) ON ARBUSCULAR MYCORRHIZAL COMMUNITIES. Jocelyn Tsai¹, Laura Beaton¹, and Tiffany Knight¹ Biology Department, Washington University, St. Louis, MO¹.

Garlic mustard (Alliaria petiolata), an invasive exotic biennial from Europe, rapidly invades North American forests, completely displacing the native plant community. It out competes native plants by releasing glucosinolates into the soil. The break down products have been found to inhibit the germination of arbuscular mycorrhizal fungal spores and consequently the growth of native plants that depend on such beneficial soil mutualists.

The aim of this study was to examine whether or not mycorrhizal systems have adapted in response to the presence of garlic mustard. We compared mycorrhizal colonization of corn roots grown in soil collected from a twenty year old garlic mustard population, a ten year old population, and one site free of garlic mustard in the presence or absence of the invasive plant.

We found that there was an interaction between the soil type and the garlic mustard treatment. Garlic mustard reduced mycorrhizal associations in the corn growing in the soil from the uninvaded site, but did not impact the number of mycorrhizal associations in corn growing in soil from the two historically invaded sites. The study shows that mycorrhizal communities have the capability to change and adapt in response to garlic mustard. Over time, the garlic mustard may lose its advantage over native plants in its ability to harm the soil communities. Finally, the similar mycorrhizal levels found in the soil in the historically invaded sites with or without the presence of garlic mustard implies that the reintroduction of mycorrhiza when restoring sites historically invaded sites is not needed.