Response of Microbial Community Structure and Changes in Carbon and Nitrogen Cycling Functional Genes during Ecological Restoration in Rocky Slopes Areas

To address the ecological restoration needs of steep rocky slopes in southwestern China, this study systematically investigated the mechanisms by which bioremediation technologies influence soil microbial community structure and functional genes involved in carbon and nitrogen cycling. By spraying composite microbial agents (containing functional strains such as Clostridium and Desulfovibrio ) and combining Illumina high-throughput sequencing with metagenomic analysis, we evaluated dynamic changes in soil fertility, microbial diversity, and functional genes over a 13 months restoration period. The results showed that total nitrogen (TN), total carbon (TC), and organic matter (OM) contents in the bioremediation area increased by 547.4%, 540.6%, and 1765.7%, respectively, compared to the natural crust group, significantly enhancing the nutrient supply capacity of barren rocky soil. Microbial diversity and richness increased, with functional phyla such as Proteobacteria and Actinobacteriota exhibiting abundance increaseed of 24.5% and 3.4%, respectively, driving synergistic enhancement of carbon, nitrogen, and phosphorus cycling. Metagenomic analysis revealed that carbon fixation genes and nitrogen fixation gene clusters (e.g., nifZ , nifX ) were upregulated in the restoration group compared to the control group. This enhancement was achieved by regulating CO2 hydration and biological nitrogen fixation pathways, significantly improving carbon and nitrogen sequestration efficiency in the ecosystem. From a molecular ecology perspective, this study elucidates the mechanism by which microbial remediation facilitates rapid ecological restoration of slopes through reshaping functional microbial networks and activating key metabolic gene expression. These findings provide a theoretical foundation for sustainable restoration of rocky slopes.