Plant invasions and the microbial community
Increasingly, studies are showing the intrinsic link between the above– and below-ground communities and how invasive alien plants can alter the soil microbial community to promote the fitness and persistence of the invasive plant population. In a study conducted in Virginia, USA, three independent sites were selected where the first was invaded by Microstegium vimineum (Poaceae, EPPO A2 List), the second by Rhamnus davurica, and the third was invaded by Ailanthus altissima (Simaroubaceae, EPPO List of Invasive Alien Plants). Bacterial and fungal communities were sampled in the plant rhizosphere using molecular methods from beneath invaded and uninvaded vegetation at each site. The results showed that although the rhizosphere microbial community structure differed across invaded sites, the plant invasion modified the below-ground communities in similar ways. There was an increase in rhizosphere bacteria responsible for nitrogen cycling from beneath invaded vegetation compared to uninvaded vegetation and this was consistent between sites. The increase observed in the number of bacteria taxa which are responsible for nitrification support other studies that show plant invasions are associated with major changes in the nitrogen cycle. These changes can promote a positive feedback enabling the invasive plant to persist. Invaded soils were also associated with a higher abundance and diversity of fungi, which was unexpected, and further research is required to determine how this has an impact on plant invasion success. The results of this study, if supported by further studies, could have serious implications for the management of degraded land as remedial techniques may be required to restore soil properties to their former pre-invaded state thus favouring native plant restoration.
Rodrigues RR, Pineda RP, Barney JN, Nilsen ET, Barrett JE & Williams MA (2015) Plant invasions associated with change in root-zone microbial community structure and diversity. PLOS one. DOI: 10.1371/journal.pone.0141424.