Composition of rhizosphere soil bacterial and fungal communities
The composition of bacterial and fungal communities at the phylum level is shown in Figure S1. Six bacterial phyla with relative abundances higher than 1% were detected, namely, Acidobacteria, Proteobacteria, Chloroflexi, Actinobacteria, Planctomycetes and Bacteroidetes. Four fungal phyla with relative abundances higher than 1% were detected, namely, Basidiomycota, Ascomycota, Mucoromycota, and one unidentified phylum (Unclassified_k_Fungi). Based on the above bacterial and fungal data, taxonomic differences in the rhizosphere microbial communities of the different samples were analyzed (Figure 2, Table S3-S8). In terms of the bacteria, the relative abundance of Acidobacteria increased with increasing carbon sequestration ability. The difference in its abundance between the medium and high families was not significant, while the differences between the medium and low samples and the high and low samples were significant. The relative abundance of Proteobacteria declined with increasing carbon sequestration ability. There was no significant difference in its abundance between the middle and high samples, while the differences between the medium and low samples and the high and low samples were significant. The other phyla showed no significant differences among the three samples. This indicated that the carbon sequestration process in Masson pine might have a positive effect on Acidobacteria and a negative effect on Proteobacteria. In terms of the fungi, the relative abundances of Basidiomycota and Unclassified_k_Fungi increased with increasing carbon sequestration ability. The relative abundances of Ascomycota and Mucoromycota decreased with increasing carbon sequestration, but in general, the relative abundance of the four main fungi did not show significant differences among the different samples.