Impact of ecological restoration on the soil microbial communities during the restoration of damaged mountain slope in China’s Heilong River Basin

Abstract Aims This study aimed to elucidate the dynamics of soil microbial communities during ecological restoration on degraded mountain slopes, specifically comparing the impacts of two common strategies: aggregate spray-seeding and planted forest establishment, against undisturbed natural slopes, and assessing key drivers of microbial recovery. Methods and results Soil microbial community composition (bacteria and fungi), diversity, and co-occurrence network structure were analyzed 7 years after restoration initiation. Both restoration approaches facilitated microbial community recovery, with restored slope compositions converging towards natural slope baselines. Fungal communities exhibited greater OTU diversity than bacteria, attributed to engineered substrates and rapid vegetation stabilization from spray-seeding. Crucially, restoration successfully increased microbial network complexity. Spray-seeding specifically achieved network stability comparable to natural ecosystems. Significant environmental relationships were identified: soil water content (SWC) showed negative correlations with fungal richness and composition, while belowground biomass (BGB) positively correlated with bacterial composition. Conclusions Restoration effectively promotes soil microbial community recovery towards natural ecosystem states, albeit with distinct dynamics for bacteria and fungi. Fungal communities are particularly responsive to restoration techniques like spray seeding. Soil properties (SWC) and plant development (BGB) are pivotal drivers shaping microbial assemblage during restoration.