青海湖高寒湿地生态系统CO_2通量和水汽通量间的耦合关系

Coupling Relationships Between Alpine Wetland Ecosystem CO_2 and Vapor Fluxes around the Qinghai Lake

利用涡度相关技术对青海湖高寒湿地生态系统不同时间尺度CO2通量和水汽通量间的耦合关系进行了研究。结果显示:不同天气条件下青海湖高寒湿地生态系统30min净CO2交换量(NEE)与水汽通量间均显示了极显著负相关关系(P<0.0001);30 min总生态系统生产力(GEP)与水汽通量呈极显著线性正相关关系(P<0.0001);阴天水汽通量参与生态系统净CO2交换和生态系统总碳吸收的比例最高。月均30min NEE与水汽通量呈极显著线性负相关(R2=0.71,P<0.0001)。从植物返青期、生长期至枯草期,月均30min的GEP与水汽通量不仅呈极显著线性正相关(P<0.0001),且在生长期和枯黄期阶段表现出极显著一元二次多项式关系(P<0.0001)。在日尺度上,NEE日总量与日蒸散量呈极显著一元二次多项式负相关关系(R2=0.58,P<0.0001);GEP日总量与日蒸散量呈极显著指数正相关(R2=0.42,P<0.0001)。在月尺度上,NEE月总量与月蒸散量呈极显著线性负相关(R2=0.60,P<0.0001),两者还表现为极显著一元二次多项式负相关关系(R2=0.63,P<0.0001)。GEP月总量与月蒸散量呈极显著线性正相关(R2=0.51,P<0.0001),且表现出极显著指数正相关关系(R2=0.64,P<0.0001)。

This paper studied the coupling relationships between alpine wetland ecosystem CO_2 fluxes and vapor fluxes on the different time scales with the eddy covariance techniques in Qinghai Lake.Results showed that alpine wetland ecosystem half-hour CO_2 fluxes and vapor fluxes in Qinghai Lake existed in extreme significant negative relationships（P0.0001）,as well as extreme significant and positive linear relationships between half-hour gross ecosystem productivities（GEPs）and vapor fluxes,which the ratio of vapor fluxes participating in ecosystem net CO_2exchanges（NEE）and ecosystem total carbon absorption in the cloudy days was highest.The alpine wetland ecosystem monthly average half-hour NEEs and vapor fluxes showed an extreme significant negative relationship（R2=0.71,P0.0001）.From vegetation green up stage,growing stage to wilt stage,monthly average half-hour GEPs and vapor fluxes not only showed extreme significant positive linear relationship（P0.0001）,but also a quadratic polynomial one（P0.0001）at growing stage and withering stage.On the daily scale,the alpine wetland ecosystem daily total NEEand evapotranspiration in Qinghai Lake existed in an extreme significant negative a quadratic polynomial nonlinear relationship（R2=0.58,P0.0001）.The alpine wetland ecosystem daily total GEPand evapotranspiration showed an extreme significant positive exponential correlation（R2=0.42,P0.0001）.On the monthly scale,the alpine wetland ecosystem monthly total NEE and evapotranspiration in Qinghai Lake showed an extreme significant negative linear relationship（R2=0.60,P0.0001）,as well as a quadratic polynomial nonlinear negative relationship（R2=0.63,P0.0001）.The alpine wetland ecosystem monthly total GEPs and evapotranspiration showed an extreme significant positive linear correlation（R2=0.51,P0.0001）as well as a positive exponential relationship（R2=0.64,P0.0001）.