Impact of elevated CO₂ and N addition on bacteria, fungi, and archaea in a marsh ecosystem with various types of plants

The individual effects of either elevated CO₂ or N deposition on soil microbial communities have been widely studied, but limited information is available regarding the responses of the bacteria, fungi, and archaea communities to both elevated CO₂ and N in wetland ecosystems with different types of plants. Using a terminal restriction fragment length polymorphism (T-RFLP) analysis and real-time quantitative PCR (RT-Q-PCR), we compared communities of bacteria, fungi, and archaea in a marsh microcosm with one of seven macrophytes, Typha latifolia, Phragmites japonica, Miscanthus sacchariflorus, Scirpus lacustris, Juncus effusus, Phragmites australis, or Zizania latifolia, after exposing them to eCO₂ and/or amended N for 110 days. Overall, our results showed that the elevated CO₂ and N may affect the bacterial and archaeal communities, while they may not affect the fungal community in terms of both diversity and abundance. The effects of elevated CO₂ and N on microbial community vary depending on the plant types, and each microbial community shows different responses to the elevated CO₂ and N. In particular, elevated CO₂ might force a shift in the archaeal community irrespective of the plant type, and the effect of elevated CO₂ was enhanced when combined with the N effect. This study indicates that elevated CO₂ and N addition could lead to changes in the community structures of bacteria and archaea. Our results also suggest that the fungal group is less sensitive to external changes, while the bacterial and archaeal groups are more sensitive to them. Finally, the characteristics of the plant type and relevant physicochemical factors induced by the elevated CO₂ and N may be important key factors structuring the microbial community’s response to environmental change, which implies the need for a more comprehensive approach to understanding the pattern of the wetland response to climate change.