Exotic Spartina alterniflora Loisel. Invasion significantly shifts soil bacterial communities with the successional gradient of saltmarsh in eastern China

Aims: The effects of invasive plants on soil carbon (C) and nitrogen (N) cycling are widely documented, while the mechanisms of their influences on the microbial ecology of soil remain unknown. Therefore, the objective of this study was to explore variations in soil bacterial communities following plant invasion, and the mechanisms that drive these changes. Methods: An invasive perennial herb, Spartina alterniflora Loisel., was examined via 16S rRNA genetic sequencing analyses, to assess the impacts of plant invasion on soil bacterial communities compared to bare flat and native Suaeda salsa (L.) Pall., Scirpus mariqueter Tang et Wang, and Phragmites australis (Cav.) Trin. ex Steud. communities in the coastal zone of China. Results: S. alterniflora invasion significantly increased soil bacterial abundance, species richness, and diversity for soil bacterial communities compared with native communities. S. alterniflora soil revealed a unique bacterial community composition, and possessed the highest relative abundance of chemo-lithoautotrophic bacteria, photoautotrophic bacteria (e.g., Chloroflexi, and Anaerolineae), and saprophytic and copiotrophic bacteria (e.g., Bacteroidetes) among the plant communities. Conclusions: Our results demonstrated that invasive S. alterniflora significantly altered soil bacterial abundance, diversity, and community composition through increases in nutrient substrate levels and altering soil physiochemical properties. Subsequently, the modification of soil bacterial communities, especially increased relative abundances of Chloroflexi, Anaerolineae, and Bacteroidetes following S. alterniflora invasion can enhance the degradation of recalcitrant S. alterniflora materials, while inducing the accumulation of soil organic C and N. These changes further potentially impacted ecosystem C and N cycles in the coastal zone of China.