雪被对冻融期湿地土壤氮转化关键过程的影响及其微生物机制

Subnivean biogeochemical processes in wetlands during the freeze-thaw period are non-negligible on the interannual scale. How will the effects of snowpacks on the hydrothermal conditions and freeze-thaw regimes of wetland soils affect the nitrogen (N) conversion? What are the microbial mechanisms? How are the N loss characteristics of wetland soils when soils are frozen and thawed? There are few systematic studies currently. This project intends to select the typical wetland of Momoge National Nature Reserve with obvious freeze-thaw process as the research object. Based on semi-controlled and in situ simulated snowpacks experiments, indoor soil column leaching and N stable isotope microbial marking experiments, it is to reveal the effects of snowpacks on the hydrothermal conditions and freeze-thaw regimes of wetland soils, to unravel the impacts of snowpacks on wetland soil N mineralization, ammonification, nitrification and denitrification during freeze-thaw periods, to explore the key hydrothermal and freeze-thaw factors influencing N transformation in wetlands, to clarify the responses of microbial community structure to snowpacks and freeze-thaw interactions and their impact on N transformation, to analyze N loss fluxes and spatiotemporal characteristics of soil infiltration, runoff and N2O emissions in wetlands, and to propose N regulation strategies based on the former results. It helps to perfect the theory of biogeochemical processes in wetlands so as to guide the N management and productivity improvement in wetland ecosystems.

雪被下冻融期湿地土壤生物地球化学过程在年际尺度上是不可忽视的。雪被对湿地土壤水热条件和冻融情势的影响将对氮转化产生怎样作用？其微生物机制是什么？雪被下冻融期湿地土壤的氮流失特征如何？目前缺少系统研究。本项目拟选取冻融过程明显的莫莫格国家自然保护区典型湿地为研究对象，基于野外雪被半控制和原位模拟观测、室内土柱淋溶和氮稳定同位素微生物标记实验，揭示雪被对湿地土壤水热条件和冻融情势的影响，阐明雪被对冻融情景下湿地土壤氮矿化、氨化、硝化和反硝化等关键转化过程的影响，探寻雪被和冻融情景下影响湿地土壤氮转化过程的关键水热和冻融情势因子，分析驱动湿地土壤氮转化的微生物群落结构对雪被和冻融作用的响应以及这种变化对氮转化过程的影响，阐述雪被下冻融期湿地土壤侧渗、径流和N2O排放过程的N流失通量及其调控策略。有助于完善湿地土壤生物地球化学过程理论，在实践上为湿地生态系统氮素管理与生产力提升提供指导。

雪被下冻融期湿地土壤生物地球化学过程在年际尺度上是不可忽视的，雪被对湿地土壤水热条件和冻融情势的影响对氮转化产生的作用以及微生物机制目前缺少系统研究。本项目选取冻融过程明显的典型湿地为研究对象，基于野外雪被控制和原位模拟观测实验以及室内实验，揭示雪被对湿地土壤水热条件和冻融情势的影响，阐明雪被对冻融情景下湿地土壤氮矿化、氨化、硝化和反硝化等关键转化过程的影响，探寻雪被和冻融情景下影响湿地土壤氮转化过程的关键水热和冻融情势因子，分析驱动湿地土壤氮转化的微生物群落结构对雪被和冻融作用的响应以及这种变化对氮转化过程的影响，阐述雪被下冻融期湿地土壤土壤氮-植物-微生物对冻融-水耦合作用的响应机制。有助于完善湿地土壤生物地球化学过程理论，在实践上为湿地生态系统氮素管理与生产力提升提供指导。