冠层叶绿素荧光角度校正及对植被总初级生产力的估算精度的影响

本研究在典型小麦区建立多角度叶绿素荧光观测系统,对多角度叶绿素荧光进行了热点方向角度订正并计算角度校正后冠层总的荧光,利用叶绿素荧光角度校正模型校正后提高了初级生产力的估算精度。结果表明：角度校正后的冠层荧光和热点荧光估算GPP的相关系数(R²)分别提高0.22±0.06和0.23±0.02。厘清不同条件下阴叶和阳叶对冠层SIF和GPP的贡献差异,分析利用SIF估算GPP的误差,优化基于SIF的GPP估算模型。

Angular normalization of ground observations of sun-induced chlorophyll fluorescence for assessing vegetation productivity

In this study, we normalize ground observations at multiple angles on clear days to the hotspot direction (SIFhotspot) and compute a weighted sum of SIF (SIFcanopy) from sunlit and shaded leaves to represent the canopy. Angular normalization of multiple angle SIF measurements significantly improved the correction of SIF to GPP derived from EC measurements over a wheat canopy. The total canopy SIF (SIFcanopy) and the SIF in the hotspot direction (SIFhotspot), obtained after the angular normalization, are better correlated with GPP than the original SIF observation. The coefficients of determination (R²) increased by 0.22±0.06 and 0.23±0.02 using SIFcanopy and SIFhotspot, respectively, after the angular normalization.