Simulated Trampling Disturbance Alters Biocrust Microbial Communities and Soil Functions: A Container‐Based Mesocosm Experiment

ABSTRACT Biological soil crusts (biocrusts) are crucial components of dryland ecosystems; however, they are highly vulnerable to anthropogenic disturbances, particularly trampling caused by grazing. To evaluate the impacts of trampling on biocrust structure, microbial communities, and soil functions, we conducted a mesocosm‐based simulated disturbance experiment (D1: moderate; D2: severe) on cyanobacteria‐ and moss‐dominated biocrusts, respectively, in Qubqi desert, China. After 1‐year natural recovery, results indicated that disturbance significantly reduced biocrust thickness, soil carbon and nitrogen content, with more pronounced effects under D2 treatment. Regardless of biocrust type, bacterial communities were dominated by Cyanobacteria, Proteobacteria, and Actinobacteria, with their relative abundances varying across disturbance gradients. Notably, stress‐tolerant taxa such as Actinobacteria tended to increase in both biocrust types under D2 treatment, although these changes were not statistically significant. Compared to cyanobacteria‐dominated biocrusts, moss‐dominated biocrusts had lower Cyanobacteria abundance, with Proteobacteria becoming the more dominant phylum; however, the relative abundance of Proteobacteria declined significantly under D2 treatment. In contrast, fungal communities remained relatively stable across all treatments in both biocrust types, with Ascomycota consistently dominating. Mantel tests further revealed community structures of Proteobacteria, Actinobacteria, Cyanobacteria, and Ascomycota were strong associations with the soil nutrient profiles. Overall, microbial community restructuring and soil functional degradation became evident with increasing disturbance intensity. Distinct microbial responses and resilience to disturbance further suggest that restoration strategies based on microbial manipulation may represent an important pathway for maintaining biocrust ecosystem functioning in dryland regions.