Biocrust mediates the complexity and stability of bacterial networks in both biocrust and subsoil layers in the Tengger Desert

Background and Aims Biocrusts cover approximately 30% of the global dryland surface area, constituting a crucial atmosphere–soil interface. Bacteria living at this interface participate in almost all biogeochemical cycling processes that may profoundly alter soil and ecosystem multifunctionality and...
Ausführliche Beschreibung

Background and Aims Biocrusts cover approximately 30% of the global dryland surface area, constituting a crucial atmosphere–soil interface. Bacteria living at this interface participate in almost all biogeochemical cycling processes that may profoundly alter soil and ecosystem multifunctionality and speed up ecosystem restoration. However, the successional dynamics of bacterial communities in both biocrusts and subsoil remain largely unclear. Methods This study used α and β diversity assessments and molecular ecological networks to reveal the bacterial community succession in biocrusts and subsoil along a 65-year succession sequence (a succession of biocrust types ranging from cyanobacteria to lichens to mosses) on the southeastern edge of the Tengger Desert. Results Our results showed that the bacterial α and β diversity and network complexity in the biocrusts and subsoil increased with succession. In the process of succession, there were distinct differences observed in bacterial community diversity and network complexity and stability between biocrusts and subsoil. In particular, the subsoil bacterial network properties, including nodes, links, average links per node, average clustering coefficient, connectance and relative modularity, were significantly higher than those of biocrust in late succession. Based on piecewise SEM, we also found that succession, soil physicochemical conditions, and biocrust bacterial community composition were the strongest direct drivers of subsoil bacterial community composition. The plant communities and biocrust bacterial community composition directly drove the network complexity and stability of the subsoil bacterial community. Conclusion Our findings indicate that under the cover and protection of the biocrust layer, the diversity of the bacterial community in the subsoil layer increased more obviously, and the network was more complex and stable. This may emphasize the important roles of biocrusts as mediators of soil microbial communities. Ausführliche Beschreibung