西双版纳热带雨林土壤N2O生产的微生物学过程：基于野外原位15N示踪的研究

为探明热带雨林土壤N2O生产的地下微生物学过程（自养硝化、异养硝化、反硝化、共反硝化）的时（季节）空（深度）动态及驱动因子，本研究利用15N示踪技术，在西双版纳热带雨林，开展有机氮（C2H515NO2），铵态氮（15NH4NO3）和硝态氮（NH415NO3）的野外原位标记和实验室培养实验，探索热带雨林土壤N2O产生的微生物学过程的时空动态；量化各微生物学过程对土壤N2O排放的贡献；结合凋落物、穿透水对土壤不同形态碳氮的供给动态，表层到深层土壤氮矿化、硝化、反硝化、氨化特征、土壤氮转化过程功能基因的量化及降水、温度和土壤孔隙含水量等要素的动态，筛选土壤N2O生产的各微生物学过程的驱动因子，并结合长期持续观测得到的N2O基础数据和氮生物地球化学过程的研究成果，阐明各微生物学过程对热带雨林土壤和该生态系统氮循环的贡献。发表论文4-6篇（SCI 2-4篇），培养博士生1名，硕士生2名。

The important focal point of our proposed research is to investigate the spatio-temporal dynamics and drivers of soil microbial processes (both auto and heterotrophic nitrification, denitrification and co-denitrification) of soil N2O production in a primary tropical rainforest in Xishuangbanna. We will set up 15N labeled in-situ and lab incubation using Glycine (13C2H515NO2), ammonia （15NH4NO3） and nitrite（NH415NO3）as a vital nitrogen source. Based on the continuous observation, the project will explore the spatio-temporal dynamics of soil N2O emission through microbial processes. The study will also quantify the different contributing factors of microbial process on soil N2O efflux. In order to achieve the inherent drivers of soil microbial processes, we will implement the combined analysis of functional gens of soil N cycle along with soil profiles. The study will also determine the controlling factors of carbon and nitrogen input variation as source of litter, throughfall, rainfall, temperature and soil water filled pore space (WFPS). The expected outcome from this research will with the long term ongoing soil N2O flux data and the N biogeochemistry researches together, will clarify the significance of soil N2O microbial processes in soil and ecological N cycles in tropical rainforest ecosystem. The collected data will be published (4-6 research papers) in the peer reviewed journals for the scientific community, which will be including 2-4 high impact factor science citation index (SCI) journals. Proposed project will be helpful for the 3 graduate students (1 Ph.D candidate, 2 graduate students) and get train them in this topic.