PS 11-139 - Invasive plant species associated with lower belowground bacterial diversity in New Jersey forests

Abstract: Invasive plant taxa have the capacity to dramatically impact the communities they are introduced to in a wide variety of ways, including production of compounds like allelopathic compounds. Due to a historical focus on plant-plant interactions, however, impacts on belowground taxa are less well explored. In this project we examined the impact of two allelochemical producing plant species invasive to New Jersey, Mile-a-Minute (Persicaria perfoliata) and Buckthorn (Rhamnus cathartica), on the belowground bacteria. We predicted that the presence of these invasive plant would alter and potentially destabilize the local bacterial community and tested this by collecting samples from woodlands that contained neither species, either species in isolation, or both species (n=3). We then used metabarcoding for the 16S rRNA gene to identify and estimate members of the bacterial community in each type of environment. Total genomic DNA was isolated, the V3-V4 region of the 16S rRNA gene was amplified using PCR, and samples were then submitted for amplicon sequencing. Taxa identification and abundance estimates were generated in QIIME2 and subsequent analyses were performed using R. Once estimates for bacterial species were generated we used a combination of Permutational Multivariate Analysis of Variance (PERMANOVA) and Non-Metric Multidimensional Scaling (NMDS) to determine if there were differences in the presence or absence of these plant species. Our results indicate that the presence of these two plant species can significantly change bacterial community composition and both species together compound the effect. Some important groups, such as nitrogen fixing bacterial taxa, are particularly suppressed when exposed to these invasive plants. Overall, our findings suggest that researchers should integrate belowground effects of invasive plant taxa when considering community level changes to invaders that employ traits such as chemical defenses to better explain indirect impacts.