Diurnal and Seasonal Solar Induced Chlorophyll Fluorescence and Photosynthesis in a Boreal Scots Pine Canopy
Diurnal and Seasonal Solar Induced Chlorophyll Fluorescence and Photosynthesis in a Boreal Scots Pine Canopy
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DOI：
10.3390/rs11030273
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发表时间：
2019-01
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影响因子：
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通讯作者：
C. Nichol;G. Drolet;A. Porcar-Castell;T. Wade;Neus Sabater;E. Middleton;C. MacLellan;J. Levula;I. Mammarella;T. Vesala;J. Atherton
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作者：
C. Nichol;G. Drolet;A. Porcar-Castell;T. Wade;Neus Sabater;E. Middleton;C. MacLellan;J. Levula;I. Mammarella;T. Vesala;J. Atherton
太阳诱导的叶绿素荧光已被证明是越来越有用的代理估计的总初级生产力（GPP），在一系列的空间尺度。在这里，我们探索的季节性在一个连续的时间序列冠层太阳诱导荧光（以下简称SiF）和冠层总初级生产力（GPP），冠层光利用效率（LUE），并直接估计在万年青冠层的叶水平光化学效率的关系。使用一对Ocean Optics USB 2000+光谱仪在双视场模式下操作，使用自定义编写的自动化软件以30分钟的时间步长采样，从早春到2011年秋季，使用来自入射和反射辐射的两个波段中的填充来计算SiF。光学系统安装在塔上的18米高的涡度协方差系统附近，观察以苏格兰松为主的北方森林生态系统。将Walz MONITORING-PAM多荧光计系统同时安装在冠层内，与光学系统采样的足迹相邻。O2和结构效应的SiF数据校正后，SiF，SiF产量，LUE，光化学反射指数（PRI），和归一化差异植被指数（NDVI）表现出季节性模式，遵循GPP采样涡度协方差系统。由于太阳方位角和天顶角（SZA）在整个季节对SiF信号的复杂性，在SZA <50°和严格晴朗的天空条件下评估SiF、SiF产量、GPP和LUE之间的相关性。发现的相关性，即使在这些筛选的情况下，导致约r2 = 0.3。SiF、SiF产率、PAM估算的有效量子产率（ΔF/Fm′）和气象参数的日变化表现出一定的一致性。固有的挑战SiF检索在北方万年青生态系统进行了讨论。
Solar induced chlorophyll fluorescence has been shown to be increasingly an useful proxy for the estimation of gross primary productivity (GPP), at a range of spatial scales. Here, we explore the seasonality in a continuous time series of canopy solar induced fluorescence (hereafter SiF) and its relation to canopy gross primary production (GPP), canopy light use efficiency (LUE), and direct estimates of leaf level photochemical efficiency in an evergreen canopy. SiF was calculated using infilling in two bands from the incoming and reflected radiance using a pair of Ocean Optics USB2000+ spectrometers operated in a dual field of view mode, sampling at a 30 min time step using custom written automated software, from early spring through until autumn in 2011. The optical system was mounted on a tower of 18 m height adjacent to an eddy covariance system, to observe a boreal forest ecosystem dominated by Scots pine. (Pinus sylvestris) A Walz MONITORING-PAM, multi fluorimeter system, was simultaneously mounted within the canopy adjacent to the footprint sampled by the optical system. Following correction of the SiF data for O2 and structural effects, SiF, SiF yield, LUE, the photochemicsl reflectance index (PRI), and the normalized difference vegetation index (NDVI) exhibited a seasonal pattern that followed GPP sampled by the eddy covariance system. Due to the complexities of solar azimuth and zenith angle (SZA) over the season on the SiF signal, correlations between SiF, SiF yield, GPP, and LUE were assessed on SZA <50° and under strictly clear sky conditions. Correlations found, even under these screened scenarios, resulted around ~r2 = 0.3. The diurnal responses of SiF, SiF yield, PAM estimates of effective quantum yield (ΔF/Fm′), and meteorological parameters demonstrated some agreement over the diurnal cycle. The challenges inherent in SiF retrievals in boreal evergreen ecosystems are discussed.