Keystone and Shared Taxa of Rhizosphere Bacteria and AMF Drive Leymus chinensis Biomass in Grazing Exclusion Grasslands

Grazing exclusion is a fundamental measure in current grassland nature‐based restoration practices. Native plants and the core microbiome are key for grassland restoration, but the rhizosphere core microbiome of Leymus chinensis grassland after long‐term grazing exclusion is poorly studied. We examined the bacterial communities and arbuscular mycorrhizal fungi (AMF) communities across 12 samples of L. chinensis rhizosphere from a long‐term grazing exclusion area. The assembly of bacteria is dominated by deterministic processes (|β‐NTI| > 2: 63.64%, MST < 0.5: 84.85%), and AMF is dominated by stochastic processes (|β‐NTI| < 2: 60.61%, MST > 0.5: 56.06%). Compared to AMF, the bacterial community exhibits significantly higher stable (robustness: 0.1937–0.2875), stress‐resistant (reciprocal of the vulnerability: 25.613–100.804), and cohesion (1.4232–1.5815) community structure characteristics after long‐term grazing exclusion. We selected keystone, shared, specialist, and generalist taxa in the rhizosphere bacteria and AMF communities, and verified that the selected microbial taxa were all significantly and positively correlated with the biomass and nitrogen and phosphorus uptake of L. chinensis. We demonstrated that the shared taxa and keystone taxa of bacteria, and the shared taxa of AMF, significantly contribute to the biomass of L. chinensis. Among the 10 selected core microbial taxa mentioned above, the relative abundance of five bacterial genera and two AMF OTUs all exceeds 1%. Therefore, when utilizing the core microbiome for grassland restoration, high‐abundance keystone and shared microorganisms in the rhizosphere of native plants should be given special attention, as they have higher potential in promoting the growth of plants and the restoration of degraded grasslands.