基于涡度相关技术,对重庆市缙云山观测站内的针阔混交林生态系统的净辐射(Rn)、显热通量(H)、潜热通量(LE)、土壤热通量(G)等进行处理,分析研究区水热通量及各环境因子的变化过程,明确水热通量变化的外在驱动因子,为森林经营及林业可持续发展提供科学依据.结果表明:1)该生态系统能量闭合缺失为0.26.2)各水热通量在日变化上呈现单峰变化趋势,在季节变化上呈现出夏季最大(日均值124.66 W/m2),冬季最小(日均值31.68 W/m2);空气温度(Ta)、饱和水气压差(VPD)呈现多峰变化趋势;降水集中于一年的4、7、8,9和10月;叶面积指数(LAI)在生长季(4-10月)呈现单峰变化.3)非雾天情况下显热通量(H)显著大于雾天情况,冠层导度(Gs)表现出多维度的复杂特征.缙云山针阔混交林能量循环损失较小,数据可靠;太阳高度角变化引起的净辐射变化是水热通量变化的主导因素;降水量(Pr)的不规则分布及LAI的变化导致Ta和VPD多峰变化;雾气对土壤热量的导向会造成显热通量下降;较高的空气温度导致了大气与下垫面之间湍流形式的热流显著增加而使显热通量上涨.一般情况下,H主要受到Rn的影响,且分别受到VPD和土壤温度(Tsoil)的次要影响(雾天环境)以及VPD和风速WS的次要影响(非雾天环境).Rn、Gs、Ta、VPD均对LE产生显著影响,未发现研究区Pr和Tsoil与LE存在显著关系.Gs受多种因素(Rn、VPD、Ta、VWC、P等)综合影响.
[Background]Based on eddy correlation technique,the flux data in the ecosystem of coniferous and broad-leaved mixed forest in Jinyun Mountain Observation Station were processed and analyzed.[Methods]The 30-min flux data and day timescale environmental factor data in the study area was used to analyze the characteristics of heat and moisture fluxes in four seasons and the trends of environmental factors.The above analysis was also used to study the characteristics of heat and moisture fluxes in foggy and non-foggy days,the influence of environmental factors on heat and moisture fluxes.[Results]1)The energy closure rate of the ecosystem was approximately equal to 0.74.2)Each heat and moisture flux showed a single-peaked trend in daily variation.In terms of seasonal change,flux was the highest in summer(daily average value 124.66 W/m2)and the lowest in winter(daily average value 31.68 W/m2).Air temperature and vapor pressure deficit showed a multimodal-peaked trend.Precipitation was concentrated in April,July,August,September and October of one year.Leaf area index showed a single-peaked trend in the growing season(April to October).3)Sensible heat flux in non-foggy days was significantly higher than that in foggy days,net radiation,canopy conductance,air temperature,vapor pressure deficit had significant effects on latent heat flux,and there was no significant relationship between precipitation,wind speed and latent heat flux was found.4)Canopy conductance showed a multi-dimensional complexity.[Conclusions]1)The energy closure state in study area is good,and the data is reliable.2)The change of net radiation caused by the change of solar altitude angle is the leading factor affecting the change of heat and moisture fluxes.Irregular distribution of precipitation and change of leaf area index lead to a multimodal-peaked trend of air temperature and vapor pressure deficit.3)The guidance of fog to soil heat will cause the decrease of sensible heat flux.Higher air temperature affects the rise of sensible heat flux.Generally,sensible heat flux is mainly affected by net radiation,respectively subject to the secondary influence of vapor pressure deficit and soil temperature(foggy environment)and the secondary influence of vapor pressure deficit and wind speed(non-foggy environment).Net radiation,canopy conductance,air temperature,and vapor pressure deficit have significant effects on latent heat flux,and there is no significant relationship between precipitation,wind speed and latent heat flux.4)Canopy conductance are affected by multiple factors(net radiation,vapor pressure deficit,air temperature,soil volumetric water content,precipitation,etc.).