4 Discussion
Based on analysis of microbial biomass C and N in H. rhamnoidespure forest (shady slope), H. rhamnoides pure forest (sunny slope), H. rhamnoides and Chinese arborvitae mixed forest, andH. rhamnoides and Pinus tabulaeformis mixed forest, we examined the driving capacity of the soil carbon (C) cycle and the mineralization and fixation of soil microorganisms on nitrogen (N). The soil microbial C and N analysis showed that soil microbial biomass N and N in different forest layers exhibited a trend of a small change with increasing soil layers; that is, as the soil depth increased, the soil microbial activity weakened gradually. A one-way ANOVA analysis of the soil microbial community showed that the difference in the soil microbial communities among different forests in the study area was smaller than was that in different soil layers. Gracilibacteria, Gemmatimonadetes, Nitrospirae, Parcubacteria, and Actinobacteria are highly correlated with most of the soil environmental factors, and Ichthyosporea and Ciliophora in fungi are correlated strongly with most of the environmental factors and are affected greatly by them. Compared with the bacterial community, the Pearson correlation between the fungal community and soil environmental factors is lower; that is, environmental factors have a greater effect on bacteria than on fungi. Conversely, the study found more species of bacteria than of fungi in the soil under the H. rhamnoides forest, which may be why there are more bacteria in the bacterial community that are significantly related to environmental factors.
Restoration mainly affects the quantity and community of soil microorganisms by affecting the litter, root morphology and secretion, and the material and energy transformation process in the whole ecosystem. To better analyze the mechanism of influence of vegetation on microorganisms and the influence of site conditions and environmental factors on soil microbial community diversity, the litter and root exudates under various H. rhamnoides forests can be studied further.
This study only addressed the soil microbial characteristics of H rhamnoides forest in the process of revegetation in Wuqi, Shaanxi Province. To better analyze the microbial characteristics of H. rhamnoides forest under the effect of revegetation in the Loess Plateau, similar studies can be conducted in other areas of the Loess Plateau. The results of these experiments can be analyzed to better explore the soil under H. rhamnoides forest in the process of vegetation diversity of soil microbial community and is expected to provide some data supporting the study of revegetation in the Loess Plateau.