Implications of diurnal changes in leaf PRI on remote measurements of light use efficiency

Matti Mõttus, Juho Aalto, Luiz Aragão, Jaana Bäck, Rocío Hernández-Clemente, Eduardo Eiji Maeda, Vincent Markiet, Caroline J. Nichol, Raimundo Cosme Oliveira, Natalia Restrepo-Coupe, Scott Salesca

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review


    The spectral properties of plant leaves reflect the state of their photosynthetic apparatus and the surrounding environment. A well-known mechanism of photosynthetic downregulation, active on the time scale from minutes to hours, is 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 thus be used to monitor the photosynthetic status of the vegetation canopy, potentially from a large distance, and allows for a global satellite-based monitoring 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 scale them to longer timescales, we measured the daily course of leaf PRI in two evergreen biomes: European boreal forest and Amazon rainforest. The daily course of PRI was different for the two locations. In Amazon, PRI was driven by incident Photosynthetic Photon Flux Density (PPFD). In the boreal location, PRI and PPFD were decoupled and PRI indicated downregulation only in the afternoon. This downregulation was confirmed with carbon exchange measurements. The study demonstrates the utility of biome-specific daily PRI curves for scaling instantaneous remote measurements to daily values and comparing data acquired at different times of day.

    Original languageEnglish
    Title of host publication2018 IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2018 - Proceedings
    PublisherIEEE Institute of Electrical and Electronic Engineers
    Number of pages4
    ISBN (Electronic)978-1-5386-7150-4, 978-1-5386-7149-8
    ISBN (Print)978-1-5386-7151-1
    Publication statusPublished - 5 Nov 2018
    MoE publication typeNot Eligible
    EventIEEE International Geoscience and Remote Sensing Symposium, IGARSS 2018 - Valencia, Spain
    Duration: 22 Jul 201827 Jul 2018


    ConferenceIEEE International Geoscience and Remote Sensing Symposium, IGARSS 2018
    Abbreviated titleIGARSS


    • Photochemical Reflectance Index
    • Light Use Efficiency
    • Boreal forest
    • Amazon rainforest
    • Pinus sylvestris
    • Betula Pendula
    • Manilkara elata


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