Stability of nitrogen-cycling microbial communities and impact on microbial nitrogen function under different land use practices

Land use management practices can strongly influence microbial community composition. However, it remains unclear whether land uses affect community stability, especially for the entire nitrogen (N) transforming community whose stability is the basis of soil microbiome N-functioning. Using metagenomic sequencing, this study investigated the co-occurrence patterns of N-cycling microbes in forest, upland, and paddy soils and their relationship with N-functional genes. The co-occurrence network structures of soil N-cycling community for these three typical land uses were completely different, with the most complex interactions observed in paddy soils (e.g. more nodes and edges, and higher average clustering coefficient, average degree, and relative modularity). The N-cyclers stability (robustness and negative: positive cohesion) in paddies was significantly higher than in uplands and forests, and lowest in forests. A random forest model revealed that soil moisture and available N emerged as the primary predictors of N-cyclers stability, with stability increasing as these factors increased. Moreover, community stability of soil N-cyclers was strongly associated with N functions. Specifically, N-cyclers stability was positively linked to multiple dissimilatory N-cycling genes and negatively correlated with several N assimilatory genes. In conclusion, our results demonstrate that land use practices significantly affect the stability of N-cycling microbial communities, which in turn influences microbial N-functionality.