呼伦贝尔羊草草甸草原CO2、CH4 和N2O 通量对放牧强度的响应机理研究

Research of terrestrial ecosystems greenhouse gas sources and sinks has been the focus that has been concerned in recent years in terms of the problems of global climate change has been facing by humanity. The project on grazing control was carried out by the method of static chamber - gas chromatography in Hulunber Leymus Chinensis meadow steppe. The change of grasslands greenhouse gases CO2, CH4 and N2O fluxes, vegetation and soil in quantitative grazing intensity were analyzed comprehensively by methods of combination of field measurements and laboratory experiments. Correlation between greenhouse gas fluxes and environmental factors (climate, vegetation, soil)was determined by analyzing grasslands greenhouse gas fluxes and vegetation biomass, soil moisture, soil total nitrogen, soil organic carbon and soil microbial biomass carbon distribution characteristics in different grazing intensities so that the response and mechanism of CO2, CH4 and N2O fluxes to quantitative grazing intensity in Hulunber Leymus Chinensis meadow steppe were revealed. Such plays an important guiding significance for the discussion of the situation of Hulunber Leymus Chinensis meadow steppe greenhouse gas sources and sinks in the global climate change law.

针对人类目前面临的全球气候变化问题，陆地生态系统温室气体源汇研究已成为近年来全球变化研究关注的热点。本项目采用静态箱-气相色谱等方法，以呼伦贝尔羊草草甸草原为主要研究对象，开展放牧控制实验，通过野外测定和室内实验相结合，综合分析定量化放牧强度下草原温室气体 CO2、CH4和N2O通量以及植被、土壤等因子的变化，对不同放牧强度下草原温室气体通量和植被生物量、土壤含水量、土壤全氮、土壤有机碳以及土壤微生物碳的分布特征进行研究，确定放牧利用强度下温室气体通量与环境因子（气候、植被、土壤）的相关关系，揭示呼伦贝尔羊草草甸草原温室气体 CO2、CH4、N2O通量对定量化放牧强度的响应机理，对于探讨呼伦贝尔羊草草甸草原温室气体源汇情况在全球气候变化规律具有重要的指导意义。

针对人类目前面临的全球气候变化问题，陆地生态系统温室气体源汇研究是近年来全球变化研究关注的热点。放牧是内蒙古呼伦贝尔草甸草原主要的利用方式，本项目采用静态箱-气相色谱等方法，以呼伦贝尔羊草草甸草原为主要研究对象，通过小区控制放牧实验（放牧强度0.00，0.23，0.34，0.46，0.69，0.92Au/hm2），探讨了不同放牧梯度下草原温室气体CO2、CH4和N2O通量变化，确定放牧利用强度下温室气体通量与环境因子（气候、植被、土壤）的相关关系，结果表明：放牧没有改变原有草原温室气体交换方向，但是改变了原有交换强度；随着放牧时间的延续，呼伦贝尔羊草草甸草原是CH4吸收的汇，是CO2和N2O排放的源。在牧草生长旺盛期土壤温室气体峰值的出现与降雨密切相关。放牧对草原土壤温室气体影响表现为长期效应，随着放牧时间的延续，整个放牧季节呈现出随着放牧强度的增加温室气体通量呈下降趋势；经过4-5年的放牧，与控制放牧相比，高强度放牧显著降低了土壤CO2排放、N2O排放和CH4吸收。土壤CO2通量与土壤水分、降雨量和地上生物量呈显著正相关，与土壤温度呈显著负相关；土壤CH4通量与地上生物量和地下生物量呈显著的负相关关系；土壤N2O通量土壤水分和地上生物量呈显著的正相关关系，与土壤微生物碳含量呈显著的负相关关系。整个样地分析，土壤CO2通量和N2O通量呈极显著正相关关系，而土壤CO2通量和CH4通量、土壤N2O通量和CH4通量呈显著负相关关系。通过研究弄清了放牧情况下草地土壤温室气体通量变化效应，为探讨呼伦贝尔羊草草甸草原温室气体源汇情况在全球气候变化规律提供了重要了理论参考。