水位变化和外源性氮增加的耦合作用对若尔盖高寒湿地CH4和N2O通量的影响机理研究

Fluxes of methane (CH4) and nitrous oxide (N2O) in terrestrial ecosystems especially in alpine wetlands are affected by the water level change and exogenous nitrogen inputs. However, it is still not clear on the magnitude and direction of CH4 and N2O fluxes affected by combined water level change and nitrogen inputs in wetlands, which significantly restricts our understanding on the driving mechanism of CH4 and N2O emission fluxes in wetlands. Therefore, we will take Zoige alpine wetland as the research object, conduct in situ or indoor experiments and used 15N isotope tracer and q-PCR methods, to elucidate the coupling effects of different water levels and nitrogen inputs on the characteristics of plant and soil, functional microorganism, and CH4 and N2O fluxes, and to reveal the contribution of exogenous nitrogen, nitrification and denitrification to the N2O flux in Alpine Wetland. The research results provide a reference for renovating degraded wetland and predicting the response of the alpine wetland to the global change.

水位变化和外源性氮增加对陆地生态系统特别是高寒湿地生态系统温室气体CH4和N2O通量产生较大影响，但目前水位变化和外源性氮增加的耦合作用对湿地温室气体CH4和N2O通量的影响还缺乏深入研究，严重制约了我们对湿地CH4和N2O排放通量的驱动因子及驱动机制的认识。因此，本项目以对全球气候变化最敏感的湿地-若尔盖高寒湿地为研究对象，采用野外原位控制实验和室内模拟实验，借助静态箱-气相色谱法、15N同位素示踪、高通量测序、q-PCR等技术，从植物、土壤特征及其功能微生物群落结构和丰度角度来分析水位变化和外源性氮增加的耦合作用对高寒湿地CH4和N2O通量的影响过程和机理，探明高寒湿地CH4和N2O通量对外源性氮增加梯度的非线性反应模式以及外源性氮、硝化和反硝化作用对N2O通量的贡献率。研究结果为退化湿地治理及预测高寒湿地对全球变化响应提供参考依据。

水位变化和外源性氮增加对陆地生态系统特别是高寒湿地生态系统温室气体CH4和N2O排放通量产生较大影响，但目前水位变化和外源性氮增加的交互作用对湿地温室气体排放通量的影响还缺乏深入研究，严重制约了我们对湿地CH4和N2O排放通量的驱动因子及驱动机制的认识。因此，本项目以对全球气候变化最敏感的湿地-若尔盖高寒湿地为研究对象，通过野外调查与原位控制实验，解析水位变化和外源性氮增加交互作用对高寒湿地温室气体排放通量的影响过程和机理。结果表明，水位变化和氮增加显著地影响着若尔盖高寒湿地温室气体排放，水位升高显著降低CO2、N2O和综合温室气体排放，而增加CH4气体排放；外源性氮增加对CH4和N2O的影响因水位不同而异。研究结果为退化湿地治理及预测高寒湿地对全球变化响应提供参考依据。