Bacterial diversity and community assembly mechanisms in alpine wetland soils under the influence of grazing

ABSTRACT Wetlands are among the world’s most significant ecosystems. Studying how different grazing intensities affect soil bacterial diversity and community assembly in alpine wetlands is crucial for their sustainable management. Based on 16S sequencing technology, this study analyzed the differences in the composition, structure, and community assembly mechanisms of bacterial communities under different grazing impacts on the Qinghai-Tibet Plateau. The research results showed that under the influence of grazing, there was no significant difference in the α-diversity of the soil bacterial community, but a certain degree of reorganization occurred at the phylum level of bacteria. At the same grazing intensity, the relative abundances of different bacterial phyla in the wetland were different, and at different grazing intensities, the relative abundances of the same phylum might have significant differences. Co-occurrence network analysis indicated that wetlands with medium grazing intensity had a higher degree of modularity. The results of the null model and neutral model showed that, with the increase in grazing intensity, the assembly process of the soil bacterial community gradually shifted from being dominated by deterministic processes to being dominated by neutral processes, with a decrease in heterogeneous selection and an increase in dispersal limitation. IMPORTANCE This work innovatively clarifies grazing’s regulatory effects on alpine wetland soil bacterial community assembly, revealing the deterministic-to-neutral shift with increasing grazing intensity and higher modularity under moderate grazing. It deepens understanding of “disturbance-microbial assembly” relationships, bridging environmental science, disturbance ecology, and microbiology. Practically, it provides a scientific basis for optimizing grazing management to maintain microbial function, crucial for sustainable management of Qinghai-Tibet alpine wetlands and similar ecosystems.