青藏高原纳木错高寒草原温室气体通量及与环境因子关系研究

青藏高原广泛分布着以高寒草甸和高寒草原为主的陆地生态系统。由于高寒草地生态系统异质性较大,对高寒草地主要温室气体通量的估算具有较大的不确定性。为研究高寒草原温室气体通量规律及其驱动因子,并为动态碳-氮耦合模式在高寒生态系统的参数化与检验提供数据支持,于2008年7-9月,使用静态箱-气相色谱法在位于青藏高原腹地的纳木错高寒草原开展了主要温室气体通量(CO₂,CH₄,N₂O)及环境因子的同步观测。结果表明:纳木错高寒草原生态系统CH₄,N₂O通量和CO₂排放分别为:-0.047 mg·m^-2·h^-1,0.49μg·m^-2·h^-1和208.2 mg·m^-2·h^-1;在季节尺度上,土壤温度与CO₂排放呈显著正相关,与N₂O和CH₄通量线性关系不显著;土壤含水量与CH₄和N₂O通量呈正相关关系,但与CO₂通量无显著相关。在日变化尺度上,土壤湿度稳定,土壤温度变化与N₂O和CO₂通量成正相关,对CH₄通量影响不显著。

CH4,N2O and CO2 Fluxes and Correlation with Environmental Factors of Alpine Steppe Grassland in Nam Co Region of Tibetan Plateau

The Tibetan Plateau is mostly covered by alpine meadow and alpine steppe.There were great uncertainties in greenhouse gases estimations for the alpine grasslands due to heterogeneity of terrestrial ecosystems.In order to verify dynamic carbon-nitrogen model,greenhouse gases fluxes and associated influencing factors were investigated.The seasonal and diurnal variations of soil CH₄,N₂O and CO₂ fluxes in an alpine steppe were measured using the static chamber and gas chromatograph method in Nam Co region of Tibetan Plateau from July to September of 2008.The mean flux rates were estimated to be-0.047 mg·m^-2·h^-1,0.49 μg·m^-2·h^-1 and 208.2 mg·m^-2·h^-1 for CH₄,N₂O and ecosystem respiration,respectively.Ecosystem respiration rates were positively correlated with soil temperature levels,whereas there were not significantly correlated with CH₄ and N₂O which are positively regulated by soil moisture variation.On the diurnal scale,the variation of temperature was positively correlated with N₂O and CO₂ fluxes,whereas there was not significant correlation with CH₄.