麦田CO_2通量、热通量特征分析

为了评价麦田生态系统CO2通量和热通量变化特征以及CO2的收支状况,利用郑州农业气象试验站2009年10月-2010年6月冬小麦生育期内涡度观测数据,分析了麦田CO2通量、热通量变化特征。结果表明:净辐射、潜热通量、显热通量和土壤热通量日变化表现为明显的单峰特征,最大值一般出现在正午前后。其中,净辐射通量、显热通量和土壤热通量的季节变化特征较为一致,均为苗期<中期<后期;潜热通量受到叶面积指数(LAI)的影响,季节变化特征为苗期<后期<中期;CO2的季节变化特征受到LAI、热通量和下垫面特征的共同影响,形成1个CO2吸收高峰的U型曲线,季节变化特征为前期<后期<中期。冬小麦农田CO2、热通量具有明显的日变化和季节变化特征,麦田生态系统总体表现为CO2的汇。

Characteristics Analysis of CO2 and Heat Flux in Winter Wheat Fields

By using the eddy covariance system data of the winter wheat growth stage from October 2009 to June 2010 at agro-meteorological experimental station of Zhengzhou,the variations of heat and CO2 flux in winter wheat fields were analyzed.The results indicated that diurnal variations of net radiation,latent heat,sensible heat and soil heat flux showed a uni-peak model,and the maximum values appeared around noon in general.The seasonal variation characteristics of net radiation,sensible heat and soil heat flux were comparatively consistent,minimum in seedling stage,next at metaphase and maximum at anaphase.Latent heat flux was affected obviously by leaf area index(LAI),which in seeding stage was minimum,next at anaphase but maximum at metaphase.CO2 flux was influenced by LAI,heat flux and the underlying surface,and its characteristics showed a U-shaped curve with an absorption peak.CO2 flux was minimum at prophase,next at anaphase but maximum at metaphase.The CO2 and heat flux in winter wheat fields had significant diurnal and seasonal variations,and overall,the ecosystem was a carbon dioxide sink for the atmosphere.