Figure captions
Fig. 1 The number of common and unique operational taxonomic units (OTUs) of rhizosphere bacterial (A) and fungi (B) under R. pseudoacacia plantations with different ages. RS15, RS25, RS35, and RS45 indicate the 15-, 25-, 35-, and 45-year-old age groups, respectively.
Fig. 2 Variation in bacterial (A, C) and fungal (B, D) β-diversity in the rhizosphere soils of R. pseudoacaciaplantations at different ages, and the contribution of soil environmental properties to microbial β-diversity based on random forest analysis (E, F).
Fig. 3 Co-occurrence patterns of forest age-sensitive operational taxonomic units (fsOTUs) in the rhizosphere microbiota. (A, B) Co-occurrence networks of bacterial (left) and fungal (right) fsOTUs showing significant correlations (r > 0.07, p < 0.001). (C, D) Cumulative relative abundances (as counts per million; y-axis in ×1000) of bacterial (left) and fungal (right) fsOTUs in different network modules. The cumulative relative abundances in RS15 (brownish red), RS25 (blue), RS35 (green), and RS45 (purple) samples indicate the overall responses of forest age-sensitive modules to the different forest ages. (E, F) Abundances of bacterial (left) and fungal (right) fsOTUs following regression with rhizosphere soil multinutrient cycling index in different modules.
Fig. 4 Identification of rhizosphere core microbiota (A, B) and their contribution to soil multinutrient cycling index (C). Figures of core bacteria are shown in the top panel and figures of core fungi are in the bottom panel. Red color indicates core microbiota and blue color indicates non-core (other) microbiota. Co-occurrence networks of core and non-core microbiotas were constructed based on correlation analysis. Network degrees of core bacteria and fungi were calculated. Contributions of core and non-core microbial diversity to rhizosphere soil multinutrient cycling were estimated based on random forest analysis.
Fig. 5 Potential contributions of the core microbiota to rhizosphere soil nutrient properties based on correlation and optimal multiple regression model for major classes of the core bacteria and fungi (A-B). Color gradient represents Spearman’s correlation coefficients. Circle size represents the variable’s importance, i.e., proportion of explained variation calculated via multiple regression modeling and variance decomposition analysis.