Significant response of microbial community to increased salinity across wetland ecosystems

Soil salinity can affect microbial activities and community structure, with broader implications for carbon storage and mineralization. However, a consensus on how soil microbial communities respond to elevated salinity has yet to be reached. With the increasing salinization of coastal lowlands, a comprehensive assessment of salinity-driven microbial community shifts is crucial for understanding and predicting shifts of biogeochemical processes in response to soil salinization. Here, we conducted a meta-analysis of 21 studies to investigate the changes in soil microbial communities along salinity gradients. We found a significant reduction of prokaryotic alpha-diversity indices with increasing salinity. Prokaryotic beta-diversity was altered by elevated salinity, but significant differences were only found between samples at < 1 and > 10 ppt salinity. Compared to non-saline conditions, high salt concentrations increased the relative abundance of Bacteroidetes and Proteobacteria by 17-19%, especially that of Alphaproteobacteria and Gammaproteobacteria, but generally inhibited the rest of the dominant phyla and classes. For fungi, Ascomycota was 1.3-fold more abundant in saline environments than in non-saline environments, but Basidiomycota was 21% less. This meta-analysis reveals significant changes of microbial community composition responding to environmental salinization. With strong biodiversity reduction under saline conditions, these dominant microbial groups with high-salinity niche preference will play a stronger role in regulating nutrient and energy flow, and constraining SOC dynamics.

Automated summary

Salinity in soil can impact microbial activities and community structure, influencing carbon storage and mineralization. Research has shown that with increasing salinity, there is a significant reduction in prokaryotic alpha-diversity indices, as well as alterations in prokaryotic beta-diversity. High salt concentrations have been found to increase the abundance of certain microbial groups while inhibiting others. This meta-analysis highlights the significant changes in microbial community composition in response to environmental salinization, with implications for nutrient and energy flow regulation.