5 CONCLUSIONS
Soil depth has been shown to have important effects on soil microbial
community structures (Brewer et al., 2019). Cultivating G.
jasminoides with C. oleifera is a promising method to promote
plant growth. It increases the soil fertility and microbial diversity
and promotes the network structure and growth of key microbial
organisms, improving potential ecosystem functioning in C.
oleifera plantations. These beneficial effects were more pronounced
when different forest types were examined and were less apparent when
the soil depth and slope position were analyzed. When G.
jasminoides was introduced into the C. oleifera stand, it
significantly affected microbial communities and the soil
physicochemical properties. The SOC, HC, and TOC content levels were
higher in the G. jasminoides with the low-yielding C.
oleifera forest than in the other stands. As revealed by the SEM, pH,
and NH4–N were the principal drivers shaping the soil
microbial structure, and microbial composition was significantly
influenced by land use change rather than by depth and slope position.
The litter from multiple tree species improves soil structure and
promotes the build-up of diverse microbial communities when compared
with homogenous litter. Replacing monocultures with mixed-species stands
is a promising approach for the maintenance of soil biodiversity and
stability and the improvement of soil nutrient content.