- 1Poznan University of Life Sciences, Faculty of Environmental and Mechanical Engineering, Department of Ecology and Environmental Protection, Laboratory of Bioclimatology, Poznan, Poland (abdallah.abdelmajeed@up.poznan.pl)
- 2Laboratory of Earth Observation, Image Processing Laboratory, University of Valencia, C/Catedrático Agustin Escardino, n° 9, 46980 Paterna, Spain
- 3JB Hyperspectral Devices, Am Botanischen Garten 33, 40225 Düsseldorf, Germany.
- 4European Space Agency, ESTEC. Noordwijk, the Netherlands
The Fluorescence Explorer (FLEX) mission aims to monitor vegetation sun-induced chlorophyll fluorescence (SIF), a proxy for ecosystem health. Studying photosynthesis and its relationship with SIF provides valuable insights into the physiological responses of ecosystems to environmental stress. Peatlands are among the most valuable ecosystems in the carbon cycle, acting as carbon storage and sinks in normal conditions but becoming carbon sources in drought conditions.
This study investigates the correlation between SIF and Gross Primary Productivity (GPP) in the temperate peatland in Poland. Measurements by the FloX system with a temporal resolution of ~30 seconds between June and October 2019 and CO2 fluxes measured by manual chambers were used for this purpose. GPP was calculated from the subsequent net ecosystem exchange and respiration measurements, and the gaps between measurements were modelled with a Michaelis-Menten rectangular hyperbola. SIF was retrieved using the Improved Fraunhofer Line Depth (iFLD) Spectral Fit Method (SFM) and Spectrum Fitting (SpecFit) algorithms in the O2-A and O2-B bands. The data were analysed at different time intervals (30 min, 1 h, 3 h, whole day, and the entire dataset).
Our results show that the strength of the SIF-GPP relationships changes significantly with time interval. Correlations tend to weaken or break (r2 <0.5) more frequently at shorter intervals, while stronger, more consistent relationships are observed over full-day periods or when the entire dataset is combined. This highlights the importance of temporal resolution when interpreting SIF-GPP relationships. Although exponential correlations have been observed at whole-day or dataset scales, these patterns may mask short-term physiological responses and stress dynamics under varying environmental conditions.
As the FLEX satellite will only provide one observation per day, our results emphasize the limitations of single daily measurements, which are influenced by transient weather conditions or plant stress. Therefore, continuous ground-based spectral data are essential to improve the reliability of SIF-based ecosystem monitoring.
This study emphasizes the importance of temporal resolution in SIF-GPP analyses and contributes to the validation efforts of the FLEX mission. Future research should validate these results across other ecosystems and integrate data from the ESA FLEXSense tandem campaigns (2018–2019) to improve global photosynthesis monitoring.
The National Science Centre, Poland, funded the 2020/39/O/ST10/00775 research.
How to cite: Abdelmajeed, A. Y. A., Cendrero-Mateo, M. P., Antala, M., Albert-Saiz, M., Stróżecki, M., Rastogi, A., Julitta, T., Burkart, A., Schuettemeyer, D., and Juszczak, R.: Assessing SIF-GPP Relationships in Peatlands: Temporal Insights for FLEX Mission Validation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18025, https://doi.org/10.5194/egusphere-egu25-18025, 2025.
