Garlic mustard and its effects on soil microbial communities in a sandy pine forest in central Illinois

This study evaluated the impacts of garlic mustard (Alliaria petiolata), an invasive species, on soil microbial community dynamics in a pine plantation on sandy soils in central Illinois. In situ soil carbon dioxide efflux was significantly greater in invaded sites. Similarly, in vitro carbon mineralization was significantly greater for soils collected from invaded sites, but only early in the incubation period. Incubations with selective inhibitors showed a decrease in fungi relative to bacteria. Nitrogen-free selective agar plates inoculated with soil slurries supported greater numbers of bacterial colonies on invaded soils. Overall, our studies suggest that garlic mustard invasions have the potential to shift microbial community structure by selectively increasing some bacterial populations and decreasing fungal populations. Furthermore, garlic mustard invasions may significantly affect microbes involved in nitrogen turnover, suggesting that removal of this invasive species may not be sufficient to restore soil microbial community dynamics and ecosystem function.