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Diurnal and Seasonal Solar Induced Chlorophyll Fluorescence and Photosynthesis in a Boreal Scots Pine Canopy

Summary

Published in Remote Sensing 11(3): 273. https://doi.org/10.3390/rs11030273

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) AWalz 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.

Sector(s): 

Forests

Categorie(s): 

Scientific Article

Theme(s): 

Ecosystems and Environment, Forest Growth and Yield Modelling, Forestry Research, Forests

Departmental author(s): 

Drolet, Guillaume

Author(s)

NICHOL, Caroline J., Guillaume DROLET, Albert PORCAR-CASTELL, Tom WADE, Neus SABATER, Elizabeth M. MIDDLETON, Chris MACLELLAN, Janne LEVULA, Ivan MAMMARELLA, Timo VESALA, Jon ATHERTON

Year of publication :

2019

Format :

Paper

ISSN

2072-4292

Keywords :

écologie forestière, modélisation de la croissance et du rendement des forêts, SiF, GPP, LUE, FLD, article scientifique de recherche forestière, forest ecology, forest growth and yield modelling, solar-induced chlorophyll fluorescence, seasonal dynamics, photosynthertic efficiency, proximal remote sensing, coniferous forest, gross primary productivity, light-use efficiency, Fraunhofer Line Discriminator, flux towers

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