Long-term legacies and partial recovery of mycorrhizal communities after invasive plant removal

Abstract

Invasive plants can have strong impacts on native communities, which have prompted intense efforts at invasive removal. However, relatively little is known about how native communities will reassemble after a dominant invader has been removed from the system. Legacy effects of invasive plants on soil microbial communities may alter native plant community reassembly long after the invader is gone. Here we found that arbuscular mycorrhizal fungal (AMF) communities have shown some recovery in experimental plots following 6 years of removal of the invasive Alliaria petiolata (garlic mustard, a species known to degrade AMF communities) in terms of taxonomic richness and community composition. However, despite this recovery, the density of A. petiolata at the beginning of the experiment (in 2004) still correlated with lower AMF richness and altered community composition after 6 years of annual weeding, suggesting long-term legacies of dense A. petiolata infestations. Because native plant and mycorrhizal fungal communities may show interdependence, reassembly of one community may be limited by the reassembly of the other. Restoration may be more effective if practices address both communities simultaneously.