Quantitative microbial element cycling reveals distinct functional characteristics associated with soil carbon and nitrogen cycling in clear-cut black locust plantations in winter

Soil microorganisms play important roles in shaping soil nutrient cycling processes. Microorganisms enter dormancy, an important process that affects soil carbon and nitrogen cycling during the subsequent growing season, in winter. However, the microbial functional potential for nutrient cycling in soils in winter remains largely unknown. The productivity of black locust decreases after two or three clear-cuttings, which influences the soil nutrient content. Thus, in this study, we selected non-clear-cut, once clear-cut and twice clear-cut black locust stands in Mount Tai. Despite notable changes in the microbial biomass C and C/N ratio ( p < 0.05), the 16S and 18S gene copy numbers did not significantly change with increasing number of clear-cut treatments ( p > 0.05). In terms of the C cycle, the abundance levels of most functional genes involved in carbon degradation, carbon fixation, and methane oxidation increased with increasing number of clear-cuts, suggesting that clear-cutting accelerated the C cycle in soil. With respect to the N cycle, the abundance levels of most functional genes related to denitrification increased with increasing number of clear-cuts, suggesting that clear-cutting also accelerated the N cycle. The soil carbon and nitrogen cycles are influenced mainly by soil and root properties and soil enzyme activity. Partial least squares path modelling (PLS-PM) revealed that changes in the soil carbon and nitrogen cycles were directly affected by soil characteristics (soil enzymes, soil nutrient content, and soil fungal and bacterial copies) and indirectly affected by plant-related effects (soil enzymes). These findings indicate that in clear-cut plantations, soil and root properties may influence soil carbon and nitrogen cycling. This study demonstrates that winter clear-cutting accelerates soil C/N cycling through gene-specific microbial responses mediated by soil–root feedbacks, thus revealing clear-cutting-related ecological risks for plantation management. • Clear-cutting accelerates soil C and N cycling rates and intensity during winter • Clear-cut induces differential responses in soil C/N cycling functional genes • Soil properties directly regulate carbon cycling processes • Root traits indirectly regulate soil carbon cycling via enzyme mediation • Soil and root properties indirectly regulate N cycling via microbial pathways