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Diurnal and Seasonal Dynamics of Solar-Induced Chlorophyll Fluorescence, Vegetation Indices, and Gross Primary Productivity in the Boreal Forest

Pierrat, Zoe and Magney, Troy and Parazoo, Nicholas C. and Grossmann, Katja and Bowling, David R. and Seibt, Ulli and Johnson, Bruce and Helgason, Warren and Barr, Alan and Bortnik, Jacob and Norton, Alexander and Maguire, Andrew and Frankenberg, Christian and Stutz, Jochen (2022) Diurnal and Seasonal Dynamics of Solar-Induced Chlorophyll Fluorescence, Vegetation Indices, and Gross Primary Productivity in the Boreal Forest. Journal of Geophysical Research: Biogeosciences, 127 (2). Art. No. e2021JG006588. ISSN 2169-8953. doi:10.1029/2021jg006588.

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Remote sensing of solar-induced chlorophyll fluorescence (SIF) provides a powerful proxy for gross primary productivity (GPP). It is particularly promising in boreal ecosystems where seasonal downregulation of photosynthesis occurs without significant changes in canopy structure or chlorophyll content. The use of SIF as a proxy for GPP is complicated by inherent non-linearities due to both physical (illumination effects) and ecophysiological (light use efficiencies) controls at fine spatial (tower/leaf) and temporal (half-hourly) scales. To study the SIF-GPP relationship, we investigated the diurnal and seasonal dynamics of continuous tower-based measurements of SIF, GPP, and common vegetation indices at the Southern Old Black Spruce Site (SOBS) in Saskatchewan, CA over the course of two years. We find that SIF outperforms other vegetation indices as a proxy for GPP at all temporal scales but shows a non-linear relationship with GPP at a half-hourly resolution. At small temporal scales, SIF and GPP are predominantly driven by light and non-linearity between SIF and GPP is due to the light saturation of GPP. Averaged over daily and monthly scales, the relationship between SIF and GPP is linear due to a reduction in the observed PAR range. Seasonal changes in the light responses of SIF and GPP are driven by changes in light use efficiency which co-vary with changes in temperature, while illumination and canopy structure partially linearize the SIF-GPP relationship. Additionally, we find that the SIF-GPP relationship has a seasonal dependency. Our results help clarify the utility of SIF for estimating carbon assimilation in boreal forests.

Item Type:Article
Related URLs:
URLURL TypeDescription SIF and VI data and eddy covariance data
Pierrat, Zoe0000-0002-6726-2406
Magney, Troy0000-0002-9033-0024
Parazoo, Nicholas C.0000-0002-4424-7780
Grossmann, Katja0000-0002-5154-197X
Bowling, David R.0000-0002-3864-4042
Johnson, Bruce0000-0001-9013-5774
Helgason, Warren0000-0002-7068-5717
Barr, Alan0000-0003-2717-218X
Bortnik, Jacob0000-0001-8811-8836
Norton, Alexander0000-0001-7708-3914
Maguire, Andrew0000-0002-6334-0497
Frankenberg, Christian0000-0002-0546-5857
Stutz, Jochen0000-0001-6368-7629
Additional Information:© 2022 American Geophysical Union. Issue Online: 16 February 2022; Version of Record online: 16 February 2022; Accepted manuscript online: 08 February 2022; Manuscript accepted: 29 January 2022; Manuscript revised: 27 January 2022; Manuscript received: 18 August 2021. This work was supported by NASA's Earth Science Division IDS (awards 80NSSC17K0108 at UCLA, 80NSSC17K0110 at JPL) and ABoVE programs (award 80NSSC19M0130). A portion of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. This material is also based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1650604 and DGE-2034835. Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors(s) and do not necessarily reflect the views of the National Science Foundation. DRB and TSM were funded during this time by the Macrosystems Biology and NEON-Enabled Science program at NSF (award 1926090). AJM was supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, administered by Universities Space Research Association under contract with NASA. The authors acknowledge funding by the Canadian Space Agency and Natural Sciences and Engineering Research Council of Canada (NSERC). The meteorological, soil and eddy-covariance measurements at SOBS were made with support from the Global Institute for Water Security, University of Saskatchewan. The authors thank our many collaborators, including site PIs and technicians, for their efforts in support of PhenoCam. The development of PhenoCam has been funded by the Northeastern States Research Cooperative, NSF's Macrosystems Biology program (awards EF-1065029 and EF-1702697), and DOE's Regional and Global Climate Modeling program (award DE-SC0016011). The authors acknowledge additional support from the US National Park Service Inventory and Monitoring Program and the USA National Phenology Network (grant number G10AP00129 from the United States Geological Survey), and from the USA National Phenology Network and North Central Climate Science Center (cooperative agreement number G16AC00224 from the United States Geological Survey). Data Availability Statement: PhotoSpec SIF and VI data is available at Environmental and eddy covariance data archiving is available at
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1650604
NSF Graduate Research FellowshipDGE-2034835
NASA Postdoctoral ProgramUNSPECIFIED
Canadian Space Agency (CSA)UNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
University of SaskatchewanUNSPECIFIED
Department of Energy (DOE)DE-SC0016011
National Park ServiceUNSPECIFIED
Subject Keywords:Boreal Forest; Solar Induced Fluorescence; SIF; Biosphere Remote Sensing; GPP; Vegetation Indices
Issue or Number:2
Record Number:CaltechAUTHORS:20220208-948246000
Persistent URL:
Official Citation:Pierrat, Z., Magney, T., Parazoo, N. C., Grossmann, K., Bowling, D. R., Seibt, U., et al. (2022). Diurnal and seasonal dynamics of solar-induced chlorophyll fluorescence, vegetation indices, and gross primary productivity in the boreal forest. Journal of Geophysical Research: Biogeosciences, 127, e2021JG006588.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113334
Deposited By: George Porter
Deposited On:08 Feb 2022 20:28
Last Modified:11 Mar 2022 21:04

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