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Harvard Forest Symposium Abstract 2017

  • Title: Evaluating the ability of full-wavelength solar-induced chlorophyll fluorescence spectrum to tracks seasonal variations of canopy photosynthesis in a temperate forest
  • Primary Author: Zhunqiao Liu ()
  • Additional Authors: Jim Tang (Marine Biological Laboratory)
  • Abstract:

    Solar-induced chlorophyll fluorescence (SIF) has been suggested as a novel approach for the quantification of the photosynthesis activity or gross primary production (GPP). With the development of spectroscopy technique and methodology on the spectrum retrieve, previous study showed that the method of canopy Fluorescence Spectrum Reconstruction (FSR) could be used to derive the complete full-wavelength SIF emission spectrum from 640-850 nm, which enable full exploit the correlations between SIF spectrum and GPP, instead of the individual SIF bands. The principle of FSR was based on the retrieval single band SIF from the multiple absorption lines (O2B, water vapor, and O2A) and the linear combination of several basic spectra extracted from training dataset simulated from the model SCOPE (Soil Canopy Observation, Photochemistry, and Energy fluxes) by the Singular Vector Decomposition technique. We analyzed the seasonal dynamic of full SIF spectrum and relationships between the various indices of canopy SIF spectrum and GPP in a temperate deciduous forest at Harvard Forest, Massachusetts, USA. Results showed that (1) the first emission peak (SIFred) were generally lower than the second emission peak (SIFNIR) in each full SIF spectrum because of the reabsorption of SIFred by chlorophyll within the canopy; (2) ratio of SIFred to SIFNIR varied with the leaf and canopy traits: leaf area index and chlorophyll concentration; (3) two SIF emission peaks had a stronger correlation with GPP than SIF in O2A band. Overall, full-wavelength SIF spectrum could provide much more information to quantify the photosynthesis activities.

  • Research Category: Forest-Atmosphere Exchange