Soil microbial community under bryophytes in different substrates and its potential to degraded karst ecosystem restoration

Bryophytes are a group of higher plants widely found in various habitats. These types of plants buffer the negative impact of rocky desertification process and possess a positive role in ecological succession processes mainly in degraded environment. In addition, soil and rhizospheric microorganisms play an important role in these processes. Therefore, understanding the composition and interaction of soil microbial communities under bryophytes on different substrates is critical for achieving effective utilization in the treatment of degraded ecological environments. This study compared the soil microbial communities of bryophytes in four different sites from rock surfaces, rocky desertification areas, and woods using high-throughput sequencing technology. The results indicated that different habitats have different soil microbial communities. Specifically, the bacterial α-diversity in rock surfaces was the lowest, but there was no difference in the fungal α-diversity. The relative abundances of the phyla Ascomycota, Actinobacteria, Cyanobacteria and Gemmatimonadota were higher in rock surfaces and rocky desertification areas than in the woods. However, the relative of abundances Basidiomycota, Myxococcota, and Verrucomicrobiota were lower in the former two sites than in the woods. Changes in soil bacterial and fungi community structures were influenced by soil salinity and soil water content. Soil nutrient concentration was also an important factor for regulating fungal communities. In addition, the co-occurrence network analysis revealed that microbes have complex interactions on the rock surfaces which is a harsh living environment. Moreover, several microbial members at the family level, such as Beijerinckiaceae, Sphingomoriadaceae, and Pseudonocardiaceae, were highly enriched in rock surfaces and rocky desertification areas, which led to a positive succession. These findings could not only enhance our understanding of the formation and maintenance of microbial community and diversity under bryophytes but also could provide a new idea for restoring karst rocky desertification areas by using specific microbial taxa.