Artificial restoration improved the complexity of the soil microbial co-occurrence network and the resistance of microbial communities to environmental changes in degraded sandy grassland

Previous studies on artificial restoration in degraded grasslands largely overlook the dynamic changes in soil microbial symbiotic networks and community resistance across restoration stages, as well as the underlying mechanisms driving these processes. We employed five different treatment types—natural grassland, degraded grassland, short-term restoration, medium-term restoration, and long-term restoration—to investigate the dynamic changes in aboveground vegetation, soil properties, the microbial co-occurrence network, and community resistance in degraded sandy grassland at various restoration stages. The results showed that artificial restoration significantly increased plant diversity and promoted soil nutrient content. As the restoration time increased, the compositional similarity of bacterial and fungal communities gradually converged toward that of natural grassland. Compared with degraded grassland, artificial restoration reduced modularity; however, increased the complexity of the microbial co-occurrence network, with notable shifts in the proportion of interspecific relationships. More importantly, the resistance of bacterial and fungal communities was significantly enhanced, indicating improved tolerance of soil microbial communities to environmental changes. The prolongation of restoration time and the improvement of soil properties emerged as the main driving factors behind this change. This study proves the major role of artificial restoration and restoration duration in enhancing the ecological recovery of degraded sandy grasslands. It also provides important scientific guidance for future restoration efforts. • Long-term artificial restoration enhances vegetation diversity and soil nutrients. • Artificial restoration lowers network modularity but increases the complexity. • Artificial restoration significantly boosts microbial community resistance.