author = "Mottus, Matti and Arag{\~a}o, Luiz Eduardo Oliveira e Cruz de and 
                         Back, Jaana and Hernandez-Clemente, Rocio and Maeda, Eduardo Eiji 
                         and Markiet, Vincent and Nichol, Caroline and Oliveira, Raimundo 
                         Cosme de and Restrepo-Coupe, Natalia",
          affiliation = "{Tartu Observatory} and {Instituto Nacional de Pesquisas Espaciais 
                         (INPE)} and {University of Helsinki} and {Swansea University} and 
                         {University of Helsinki} and {University of Helsinki} and 
                         {University of Edinburgh} and {Embrapa Amazonia Oriental} and 
                         {University of Arizona}",
                title = "Diurnal changes in leaf photochemical reflectance index in two 
                         evergreen forest canopies",
              journal = "IEEE Journal of Selected Topics in Applied Earth Observations and 
                         Remote Sensing",
                 year = "2019",
               volume = "00",
                pages = "1--8",
             keywords = "Amazon rainforest, Betula pendula, boreal forest, light use 
                         efficiency, Manilkara elata, photochemical reflectance index 
                         (PRI), Pinus sylvestris.",
             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 biomesa 
                         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, p < 
                         0.01) 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, p < 0.05) correlated with mean PPFD 
                         of the preceding two hours; for Betula pendula, the correlation 
                         was insignificant (p > 0.5) 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.",
                  doi = "10.1109/JSTARS.2019.2891789",
                  url = "http://dx.doi.org/10.1109/JSTARS.2019.2891789",
                 issn = "1939-1404 and 2151-1535",
                label = "lattes: 5174466549126882 2 MottusABHMMNOR:2019:DiChLe",
             language = "pt",
           targetfile = "08642393.pdf",
        urlaccessdate = "23 abr. 2021"