Soil total organic carbon/total nitrogen ratio as a key driver deterministically shapes diazotrophic community assemblages during the succession of biological soil crusts

The diazotrophic community in biological soil crusts (biocrusts) is the key supplier of nitrogen dryland. To date, there still limited information on how biocrust development influences succession community, and what are most important factors mediating communities during succession. Using high throughput nifH amplicon sequencing, diazotrophs soils at different developmental stages were comparatively studied. results evidenced decreases TOC/TN ratio pH value with development. Nostoc Scytonema dominant genera all stages, while Azospirillum Bradyrhizobium abundant only bare soil. Diazotrophic co-occurrence networks tended to be less complex connected was factor diversity, composition assembly processes, diazotrophic-diversity NO3−-N/NH4+-N positively correlated nitrogenase activity This study provided novel understandings fixation patterns by showing effects composition, networks, recognizing as