Abstract: Soil nitrogen transformation is primarily driven by related functional soil microbes. Ammonia oxidation by ammonia-oxidizing bacteria (AOB) is the rate-limiting step of nitrification. During the processes of desertification and restoration, soil microbial communities are significantly affected by the changes of vegetation and soil. In this study, we investigated the diversity and community structure of soil AOB marked by amoA gene with clone library and quantitative PCR techniques under 30-year-old Caragana microphyllasandfixation plantation and moving sandy dune in Horqin Sandy Land. We found that the diversity of AOB in the C. microphyllasoil was very low, with only some Nitrosospira species being observed. During the positive and negative processes of desertification, the structure of soil AOB communities mainly varied in quantity, while the composition of soil AOB communities remained unchanged. These results indicate that soil AOB community structure in moving sandy dune can be restored to its original condition by planting C. microphylla. Soil total N and P concentrations are major environmental factors affecting AOB community structure.

Key words: slow-release calcium peroxide, soil nutrient availability, latent environment, microbial characteristics