## 4 Discussion  
Results of this study demonstrate the relationships among soil physicochemical properties and the bacterial communities associated with three selected plants (_E. rufipilus_, _C. nepalensis_, and _P. yunnanensis_), as well as grassland plots in phosphorus-rich mountains in southwestern China. The associations among soil nutrients and bacterial community structure of rhizosphere and bulk soils has been demonstrated in several previous studies [48; 49; 50; 51; 52]. Plant species play an important role in shaping rhizosphere microbial communities through their root exudates [53; 54; 24; 55]. In this study, we found that the content of SOM, TN, and AN was present in higher concentrations in rhizosphere soils as compared with bulk soils among three plants in PES. The contents of SOM, TN, AN, TP, and AP in rhizosphere soils were elevated 55.31%, 34.11%, 39.02%, \(-\)2.11%, and 3.50% relative to bulk soil, consistent with soils from other studies and regions [56; 57]. The rhizosphere soils of _P. yunnanensis_ have higher TP content (elevated 121.44% and 189.06% relative to _E. rufipilus_ and _C. nepalensis_, respectively), AP content (elevated 115.70% and 294.24% relative to _E. rufipilus_ and _C. nepalensis_, respectively), and lower nitrogen/phosphorus (N/P) (declined 50.91% and 52.63% relative to _E. rufipilus_ and _C. nepalensis_, respectively) than the other two dominant plants. Differences in soil phosphorus content among land-use types in PES could possibly be due to geological reasons; for example, this study site is home to geological phosphorus-rich mountains, and phosphate deposited in Yunnan Province accounts for 80% of high-grade phosphate ore in China [17]. According to previous studies on PES, phosphorus is found in high concentrations in soils with low soil nitrogen content [21; 58]. Therefore, the results of this study are congruent with previous studies. The 16S rRNA gene sequencing survey provides exhaustive information about the relative abundance, diversity, and composition of bacterial communities. This study was the first implementation of Illumina MiSeq high-throughput sequencing technology on soil microbial communities in phosphorus-rich mountains. The relative abundance of bacteria among the soil samples showed that _P. yunnanensis_ had the lowest bacterial OTUs and CK had the highest. In contrast, soil nutrient properties revealed that _P. yunnanensis_ had the highest concentration of SOM, AN, TP, and AP, whereas CK had the lowest SOM. This suggests that plant species shapes soil nutrient properties and bacterial community characteristics in rhizosphere and bulk soils. The most abundant phylum of bacterial communities in the rhizosphere soil among plants was _Proteobacteria_. This result corroborates the results of several previous bacterial community studies done on the rhizosphere soils of crops [15; 59], mining soils [60; 61], and PES bacterial community research [28]. Furthermore, the class _Alphaproteobacteria_ occupied the majority of the phylum _Proteobacteria_. _Rhizobiales_ are the most abundant order in _Proteobacteria_ across all soil samples. The families _Bradyrhizobiaceae_ and _Rhizobiaceae_ in the order _Rhizobiales_ from _C. nepalensis_ have higher abundance than _E. rufipilus_, _P. yunnanensis_, and grassland plots; this is because _C. nepalensis_ forms symbiotic relationships with nitrogen-fixing bacteria [62; 63]. The phylum _Acidobacteria_ is the second most abundant community among the rhizosphere of the plants and grassland plots in this study. _Acidobacteria_ is the predominant phylum of bacteria in semi-arid and other mature soil environments [64]. _Acidobacteria_ exists most abundantly in the rhizosphere soil of _E. rufipilus_; this is likely because _E. rufipilus_ is highly drought resistant and suitable to grow in arid regions [65; 66]. As a dominant species, _E. rufipilus_ is widely distributed in phosphorus-rich regions and has a high phosphorus tolerance [63]. The next phyla in highest abundance were _Verrucomicrobia_ and _Planctomycetes_.