4.3 Role of core microbiota in rhizosphere soil nutrient cycling
Exploring core microbiota can enhance our understanding of the influence of microbial community assembly and stability on rhizosphere soil nutrient cycling (27) Therefore, in the present study, we identified the core taxa in the rhizosphere microbial communities associated withR. pseudoacacia plantations. In the microbial network, a high value represents a node and a central position, while a low value indicates a peripheral position (12, 48). We observed core taxa in rhizosphere microbial communities, which exhibited high connectivity. The results indicate that the core microbiota had a central ecological position in the rhizosphere microbial network.
High soil microbial diversity could promote multifunctionality, as reported in other terrestrial ecosystems (11, 19, 31, 49). Jiao et al. reported that core microbiota played a major role in the maintenance of microbial interactions, community stability, and belowground multinutrient cycling in agricultural fields across eastern China (25). Our results indicated that the diversity of core taxa has a greater impact on rhizosphere soil multinutrient cycling than the diversity of non-core taxa, based on random forest module. Accordingly, we concluded that the core microbiota participated in rhizosphere soil multinutrient cycling, while maintaining rhizosphere microbial network complexity. Multiple regression modeling and variance decomposition analysis revealed the potential influences of core microbiota, at the class level, on soil nutrient properties.
Some core taxa can participate in the maintenance of plant health and plant production (20, 52), and such taxa play important roles in soil multifunctionality maintenance through the promotion of nutrient exchange and facilitation of resource availability in agroecosystems (52). The core microbiota identified in the present study have been reported in other environments. For example, Acidimicrobiia are observed extensively in acidic wastewater, marine lakes, deserts, and other environments with important ecological functions and potential development values (18). Bacillus can degrade Polyhydroxy-alkanoates and promote plant growth (9, 44). So, identifying core microbiota facilitates the understanding of microbial responses to environmental disturbance (46).