Diurnal Changes in Leaf Photochemical Reflectance Index in Two Evergreen Forest Canopies

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Mõttus , M , Aragão , L , Bäck , J , Clemente , R H , Maeda , E E , Markiet , V R L , Nichol , C , Oliveira , R C & Restrepo-Coupe , N 2019 , ' Diurnal Changes in Leaf Photochemical Reflectance Index in Two Evergreen Forest Canopies ' , IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing , vol. 12 , no. 7 , pp. 2236-2243 . https://doi.org/10.1109/JSTARS.2019.2891789

Title: Diurnal Changes in Leaf Photochemical Reflectance Index in Two Evergreen Forest Canopies
Author: Mõttus, Matti; Aragão, Luiz; Bäck, Jaana; Clemente, Rocío Hernandez; Maeda, Eduardo Eiji; Markiet, Vincent Robert Leon; Nichol, Caroline; Oliveira, Raimundo Cosme; Restrepo-Coupe, Natalia
Contributor: University of Helsinki, VTT Technical Research Center of Finland
University of Helsinki, Department of Forest Sciences
University of Helsinki, TreeD lab - Terrestrial Ecosystem Dynamics
University of Helsinki, VTT Technical Research Centre of Finland
Date: 2019-07
Language: eng
Number of pages: 8
Belongs to series: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
ISSN: 1939-1404
URI: http://hdl.handle.net/10138/303229
Abstract: The spectral properties of plant leaves relate to the state of their photosynthetic apparatus and the surrounding environment. An example is the well known photosynthetic downregulation, active on the time scale from minutes to hours, caused by reversible changes in the xanthophyll cycle pigments. These changes affect leaf spectral absorption and are frequently quantified using the photochemical reflectance index (PRI). This index can be used to remotely monitor the photosynthetic status of vegetation, and allows for a global satellite-based measurement of photosynthesis. Such earth observation satellites in near-polar orbits usually cover the same geographical location at the same local solar time at regular intervals. To facilitate the interpretation of these instantaneous remote PRI measurements and upscale them temporally, we measured the daily course of leaf PRI in two evergreen biomes—a European boreal forest and an Amazon rainforest. The daily course of PRI was different for the two locations: At the Amazonian forest, the PRI of Manilkara elata leaves was correlated with the average photosynthetic photon flux density (PPFD) ( R2=0.59 ) of the 40 minutes preceding the leaf measurement. In the boreal location, the variations in Pinus sylvestris needle PRI were only weakly ( R2=0.27) correlated with mean PPFD of the preceding two hours; for Betula pendula, the correlation was insignificant regardless of the averaging period. The measured daily PRI curves were specific to species and/or environmental conditions. Hence, for a proper interpretation of satellite-measured instantaneous photosynthesis, the scaling of PRI measurements should be supported with information on its correlation with PPFD.
Subject: 1172 Environmental sciences
4112 Forestry
Amazon rainforest
Betula pendula
boreal forest
light use efficiency
Manilkara elata
photochemical reflectance index (PRI)
Pinus sylvestris
MULTIPLE DRIVERS
PRI IMPLICATIONS
SEASONAL-CHANGE
PHOTOSYNTHESIS
FLUORESCENCE
ECOSYSTEMS
EFFICIENCY
PHENOLOGY
CYCLE
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