降水格局变化和放牧对松嫩草地生态系统土壤N2O通量的影响及其机制

全球和区域尺度的降水格局发生了显著变化，将影响草地生态系统的结构和功能，改变氮循环过程以及土壤和大气的氧化亚氮通量交换。放牧是草地生态系统最广泛的利用方式之一，会显著影响植被和微生物群落结构以及土壤理化性质，调控氧化亚氮通量对降水格局变化的响应模式。然而，氧化亚氮通量对降水格局变化和放牧交互作用的响应机制还不明确。以松嫩草甸草原为研究对象，探讨降水事件对草地生态系统氧化亚氮通量的影响过程及其机制；利用15N稳定同位素示踪技术揭示降水格局变化（减少降水频率和降水量）对氧化亚氮通量的影响机制；研究降水格局变化和放牧交互作用对草地生态系统氧化亚氮通量以及植被组成、土壤理化性质和微生物群落结构的影响，量化和构建氧化亚氮通量与植被-土壤性质-微生物的关系模型，揭示氧化亚氮通量对降水格局变化和放牧互作的响应和驱动机制。为评估草地生态系统氧化亚氮通量对全球变化的响应和反馈机制提供数据基础和科学依据。

Global and regional precipitation patterns have significantly changed, which would affect the structure and function of grassland ecosystem, change the nitrogen cycle process and the nitrous oxide emissions exchange between soil and atmosphere. Grazing is one of the most widely used methods in grassland ecosystem, which could significantly affect the community structure of vegetation and microbe. However, the response of nitrous oxide emissions to changing precipitation pattern and grazing and their interaction is still unclear. The Songnen meadow grassland were selected as the research site. We studied the response of nitrous oxide emissions to precipitation events. Discussed the response of nitrous oxide emission to changing precipitation pattern (decreasing frequency and intensity of precipitation) using 15N stable isotope tracer technique. Explored the influence of changing precipitation pattern and grazing and their interaction on nitrous oxide emission, vegetation composition, soil physical and chemical properties and microbial community structure in the meadow grassland ecosystem, quantity the relationship model between nitrous oxide emissions and vegetation-soil property-microbe system, reveal the response and driving mechanism of nitrous oxide emission to changing precipitation pattern and grazing. This provides scientific basis for evaluating the response and feedback mechanism of nitrous oxide emission to global change in the grassland ecosystem.