Soil nitrogen concentrations and transformations under different vegetation types in forested zones of the Loess Gully Region

The "Grain for Green" project is essential for controlling soil erosion in the Gully Region of the Loess Plateau, which has one of the most serious water and soil loss problems in the world. Different vegetation types change the soil environment to different extents, influencing the biogeochemical cycles of materials, such as nitrogen (N). In this paper, the effect of vegetation types on the concentration and transformation of various soil N types (soil total N, organic N, N mineralizable within 14 d, microbial biomass N, nitrate N and ammonium N) in the Dongzigou Basin, Ansai, Shaanxi Province was investigated. The results showed that the six types of soil N as a whole gradually increased as vegetative succession proceeded from grass communities to more complex mixtures of trees, bushes and grasses. Further research is still required to explore the processes of vegetation change and N transformation.