Soil carbon dynamics is closely related to soil microbial process. Nitrogen deposition produces direct or indirect effect on soil microorganisms and consequently affects Soil C transformation and cycling. Microbial residues are important source to soil C pool and play essential role of soil C accumulation in long terms. Amino sugar is a biomarker of microbial residues and its accumulation and transformation is an indicator of soil organic C transformation process by microorganism. Till now, the research on the effect of N deposition on soil C dynamics has been focused on temperate forest of North sphere where N supply is limited. Little attention was paied to tropical forest where N is saturated.

Prof ZHANG Xudong and Prof HE Hongbo in the Research Group of Matter Cycle with their coworkers investigated the effect of N addition on soil microbial residues in a tropical research station-Dinghushan station using amino sugar as biomarker. It was found that N addition did not affect soil fungal and bacterial residues, but high rate (150 kg N ha^-1yr^-1) significantly reduced the contribution of microbial residue to the soil organic C. The results illustrated the changes in the contribution of microbial residues to soil organic C pool have important indication role in the prediction of the effect of global changes to soil carbon pool.

The results were published in Soil Biology & Biochemistry entitled as High Nitrogen Deposition Decreases the Contribution of Fungal Residues to Soil carbon Pools in a Tropical Forest Ecosystem. The work was supported by a 973 project (No. 2014CB954400), NNSFC (（No. 41571238, 41571237） and Special Biology Project (No. XDB15010303).