The Driving Mechanisms of Soil Microbial Community Diversity and Stability in Different Plant Communities Along the...

The Water-Level-Fluctuation Zones (WLFZ) of the Lower Jinsha River, as a typical transition areas between land and water, show crucial ecological functions. However, the relationship between soil nutrients and microbial communities in different plant communities of the WLFZ is poorly understand. Therefore, we chose four typical plant communities, including Parthenium hysterophorus (P. hysterophorus), Ziziphus mauritiana (Z. mauritiana), Cynodon dactylon (C. dactylon), Zea mays (Z. mays), as a long-term plant communities experiment-monitoring site in a WLFZ of the Lower Jinsha River. By using high-throughput sequences, Mantel test and Mediation model, we explored the changing characteristics of soil nutrients and microbial communities, especially bacteria and fungi, and their driving role in the microbial stability in four typical plant communities. The results indicated that soil properties and enzyme activities noticeably changed among four types of different plant communities in the WLFZ, of which their P. hysterophorus and Z. mauritiana treatments were eventually higher than their of Z. mays and C. dactylon treatments. In the bacteria and fungi communities, the OTU number of P. hysterophorus and Z. mauritiana treatments were higher than their of C. dactylon and Z. mays treatments, which showed that the bacterial biomarkers only explained with the order, but the fungal biomarkers could explain with species. The bacterial and fungal diversity among four types of different plant communities in the WLFZ significantly changed such that the bacterial and fungal explanations of principal coordinate analysis (PCoA) was at 42.45% and 28.17%, respectively, and the anosim analysis of bacteria and fungi showed the p was 0.001 and the R was at 0.6995 and 0.7491. The bacterial and fungal co-occurrence network patterns presented that the bacterial community structure of the C. dactylon and P. hysterophorus treatments were the most complicated under the Z. mauritiana and Z. mays treatments, whereas the communities stability of C. dactylon and P. hysterophorus treatments were notably lower than that of their Z. mauritiana and Z. mays treatments. Lastly, the CCA, mantel test and intermediary analysis indicated pH served as the primary direct driver in the Z. mauritiana community, soil moisture exerted dominant effects in Z. mays and P. hysterophorus, while in C. dactylon, bacterial stability was indirectly modulated by pH mediated through SMC changes. This study highlights the major role of soil nutrients and enzyme activities in driving ecosystem stability of bacterial and fungal communities in four different plant communities in the WLFZ.