Exotic invasive plant - soil biota interactions differentially influence plant establishment during a woodland restoration

Exotic plant species pose one of the largest threats to native ecosystems by displacing native species and/or causing fundamental changes in ecosystem function. While many studies on invasive species have focused on the aboveground community, one particularly understudied area is the potential for the soil community to respond to or mediate exotic plant invasions. This study examines the effects of Alliaria petiolata (garlic mustard) on the soil community in oak-maple woodlands undergoing restoration. We first examined the extent to which species richness and diversity in ecto (EM)- and arbuscular mycorrhizal fungal (AMF) communities were altered following the invasion of garlic mustard, and the legacy of such alterations on the growth and survival of planted oak (EM) or maple (AMF) seedlings. Next, we determined if the allelopathic effects of garlic mustard disrupted EM in oaks in a manner similar to that recently reported in AMF maples. Finally, we examined the effect of garlic mustard -induced disruptions in the mycorrhizal community on microarthropod populations in the soil, particularly on collembola that are known to graze on mycorrhizal fungi. When compared to plantings in a non-invaded site, our results highlight i) the importance of plant- mycorrhizal interactions in plant survival, and ii) how a common invader can evoke disparate responses from individual compartments of the soil community.