3.7 | Correlation analysis of soil properties and bacterial communities
We constructed SEMs to further investigate the impact of the depth, slope position, and forest type on the bacterial communities. SEM explained 83.2% and 72.1% of the variation under new afforestation and low-yield forest, respectively, (new afforestation: χ2 = 22.586, P-value = 0.832, AIC = 118.586, BIC = 161.324; low-yielding forest: χ2 = 25.086, P-value = 0.721, AIC = 121.086, BIC = 163.824) (Figure 8). G. jasminoides in a low-yielding C. oleifera forest had significant direct effects on the Shannon diversity index, while G. jasminoides in the C. oleifera new afforestation had no significant effect on the Shannon diversity index. Planting G. jasminoides in the low-yielding C. oleifera forest led to a change in the EC values, which influenced the pH values. As a direct factor, pH influenced the ACE richness index. The NH4–N to NO3–N transition was enhanced (Figure 8b). Our results suggest that planting G. jasminoidescould effectively promote the conversion of NH4–N to NO3–N in low-yielding C. oleiferaforests.