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Controls of chlorophyll fluorescence spectra vary among leaves in a boreal forest and over a spring recovery of photosynthesis

Citation

Rajewicz, Paulina et al. (2021), Controls of chlorophyll fluorescence spectra vary among leaves in a boreal forest and over a spring recovery of photosynthesis, Dryad, Dataset, https://doi.org/10.5061/dryad.mgqnk990r

Abstract

Chlorophyll fluorescence can be used to track to seasonal dynamics of photosynthesis in boreal forests. However, the relationship between chlorophyll fluorescence and photosynthesis is affected by biochemical and morphological factors, which vary across time and space as a function of light environment, species, and environmental conditions. We investigated how various factors, and their spatio-temporal dynamics during spring recovery of photosynthesis in a boreal forest, affect spatio-temporal variation in chlorophyll fluorescence spectra. The factors under consideration included: environmental variables (incoming radiation, temperature), biochemical variables (pigments), leaf morphology, and photosynthetic variables (e.g. non-photochemical quenching or carbon assimilation). Results of this analysis were presented in the article titled "Controls of chlorophyll fluorescence spectra vary among leaves in a boreal forest and over a spring recovery of photosynthesis" submitted to the Journal of Experimental Botany. On the spatial scale, we investigated chlorophyll fluorescence spectra of three evergreen species growing in different light environments. We found that spatial variation in chlorophyll fluorescence spectra was continuously related to leaf morphology and light environment throughout the study period. On the temporal scale, we assessed chlorophyll fluorescence spectra over the spring recovery of photosynthesis (from February to July 2017). In the majority of analyzed species and light environments, temporal variation in chlorophyll fluorescence was significantly correlated with photosynthetic factors, such as photochemical and non-photochemical quenching. As the main finding of this publication, we suggest that when spatial and temporal variation in leaf-level chlorophyll fluorescence spectra are interpreted in terms of photosynthesis, variation related to leaf morphology and light-environment should be taken into account.

Methods

The dataset was collected during a measuring campaign carried out at Station for Measuring Ecosystem-Atmosphere Relation (SMEAR-II) in Hyytiälä, southern Finland (61⁰50’ N, 24⁰17’ E) from February to July 2017. The data available here are raw or pre-processed and if it concerns, the pre-processing procedure is described in the readme files available in each variable-dedicated folder. The chlorophyll fluorescence dataset (folder: spectral_fluorescence) has been collected with an Optical Chamber protocol as described in the methods section of the associated manuscript referenced above. From the dataset available in this depository, the chlorophyll fluorescence data was processed by a series of Singular Value Decomposition (SVD) analyses to evaluate the relative role of vectors in explaining the spatial and temporal variation of chlorophyll fluorescence spectra. The remaining datasets (folders: PAM fluorescence, gas exchange, pigments, light environment, and SMEAR, where environmental variables from the station are available) have been used to test their correlations with the SVD vectors in order to investigate the relative roles that different variables have in controlling the spatial and temporal variation of chlorophyll fluorescence spectra. Results of these analyses have been presented in the publication titled "Controls of chlorophyll fluorescence spectra vary among leaves in a boreal forest and over a spring recovery of photosynthesis" in the Journal of Experimental Botany.

Usage Notes

The dataset is divided into folders for each of the measured variables. In the SMEAR folder, three variables regarding environmental variables of the SMEAR-II measuring station are included. In the spectral fluorescence folder, separate files for each analyzed case (species and canopy position) are included. The readme file in each folder contains an explanation of each of the variables in the dataset, its measurement device, measurement units, files layout, and pre-processing (if concerns). Information on how the measurements were done can be found in the associated manuscript referenced above.