Linking the Changes of Soil Organic Carbon with Rare Bacterial Diversity in Sagebrush Desert Grassland Under Grazing Exclusion

Grazing exclusion is an effective and economical tool for restoring degraded grasslands. Yet, less attention is paid to the changes of rare and abundant bacterial taxa and their connections with soil organic carbon changes after grazing exclusion (GE). Using high-throughput sequencing and multiple statistical methods, we assessed shifts in rare and abundant bacterial taxa and contributions to soil organic carbon in five typical sagebrush (Xinyuan, Bole, Qitai, Hutubi, Manasi) desert experimental plots in Xinjiang, northwest China. The results demonstrated that rare bacterial α-diversity decreased significantly in Xinyuan, Bole, and Qitai plots, while Hutubi and Manasi plots significantly increased during GE ( p < 0.05). GE increased the edges/nodes ratio from 29.60% to 44.90% and changed network complexity by shifting the nodes and topological properties, cohesion, and robustness in the bacterial network. The changes in rare bacterial diversity are tightly correlated with changes in soil organic carbon. The results not only underline the pivotal role of rare bacterial taxa in response to GE and soil organic carbon changes but also provide novel insights into the mechanisms of soil organic carbon changes after GE.