Microbial diversity in the rhizosphere soils of three Stipa species from the eastern Inner Mongolian grasslands

Abstract

Rhizosphere soil microorganisms affect the diversity and ecological distribution of aboveground plants and play an important role in the functions of terrestrial ecosystems. Using high-throughput sequencing, we have investigated the rhizosphere soil microbial communities of three species of Stipa from six plots, in the eastern steppe of Inner Mongolia, and analyzed the relationship between microbial diversity and vegetation diversity and soil physicochemical characteristics. The dominant bacteria phyla were: Actinobacteria, 31.73–44.73%; Proteobacteria, 15.79–23.85%; Acidobacteria, 9.42–15.14%; and Chloroflexi, 4.90–13.60%. While the dominant fungi phyla were: Ascomycota, 16.93–82.12%; Basidiomycota, 2.44–81.28%; and Zygomycota, 0.40–18.92%. Principal coordinates analysis (PCoA) indicated that the soil microbial community compositions in the Stipa baicalensis steppe in Hulunbuir and the Stipa krylovii steppe in the Xilingol plots, were significantly different from the others. The species characteristics of the plant communities were different in each plot for the vegetation diversity factors, the Shannon Weiner index, Simpson index, and the importance value indices of the Stipa and Leymus chinensis significantly affected the community structures of the bacteria and fungi. Among the physicochemical soil parameters, soil pH, ammonium nitrogen (AN), and sucrase (SC), significantly affected the community structures of the bacteria and fungi, and were inseparable from the interactions between the microorganisms and environmental factors. We found that microbial community diversity was complex in the rhizosphere soils of the Stipa, and that they were mainly affected by the vegetation diversity, soil pH, ammonium nitrogen, and soil sucrase activities. These results improve our understanding of the correlations between the Stipa rhizosphere soil microorganisms and the environmental factors, and provide guidance for future research on the distribution characteristics and growth of the Stipa.