Abstract
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 nearpolar 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.
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 nearpolar 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 language | English |
|---|---|
| Title of host publication | IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium |
| Publisher | Institute of Electrical and Electronics Engineers |
| Pages | 9007-9010 |
| Number of pages | 3 |
| ISBN (Electronic) | 978-1-5386-7150-4 |
| DOIs | |
| Publication status | Published - 1 Dec 2018 |
| Event | IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Duration: 22 Jul 2018 → 27 Jul 2018 |
Publication series
| Name | IEEE International Geoscience and Remote Sensing Symposium |
|---|
Conference
| Conference | IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium |
|---|---|
| Period | 22/07/18 → 27/07/18 |