TY - GEN
T1 - Implications of diurnal changes in leaf PRI on remote measurements of light use efficiency
AU - Mõttus, Matti
AU - Aalto, Juho
AU - Aragão, Luiz
AU - Bäck, Jaana
AU - Hernández-Clemente, Rocío
AU - Maeda, Eduardo Eiji
AU - Markiet, Vincent
AU - Nichol, Caroline J.
AU - Oliveira, Raimundo Cosme
AU - Restrepo-Coupe, Natalia
AU - Saleska, Scott R.
N1 - Publisher Copyright:
© 2018 IEEE
PY - 2018/10/31
Y1 - 2018/10/31
N2 - 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.
AB - 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.
KW - Amazon rainforest
KW - Betula Pendula
KW - Boreal forest
KW - Light Use Efficiency
KW - Manilkara elata
KW - Photochemical Reflectance Index
KW - Pinus sylvestris
UR - http://www.scopus.com/inward/record.url?scp=85063131072&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85063131072&partnerID=8YFLogxK
U2 - 10.1109/IGARSS.2018.8517554
DO - 10.1109/IGARSS.2018.8517554
M3 - Conference contribution
AN - SCOPUS:85063131072
T3 - International Geoscience and Remote Sensing Symposium (IGARSS)
SP - 9007
EP - 9010
BT - 2018 IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2018 - Proceedings
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 38th Annual IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2018
Y2 - 22 July 2018 through 27 July 2018
ER -