Liu et al. (2025) Unrevealing site-dependent relationship between solar-induced chlorophyll fluorescence and gross primary productivity using the terrestrial ecosystem carbon cycle simulator

Identification

• Journal: Remote Sensing of Environment
• Year: 2025
• Date: 2025-09-30
• Authors: Haoran Liu, Zoe Pierrat, Hamid Dashti, Min Chen
• DOI: 10.1016/j.rse.2025.115052

Research Groups

• Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, WI, USA
• Jet Propulsion Laboratory, California Institute of Technology, CA, USA

Short Summary

This study developed TECs-SIF, a terrestrial biosphere model integrating a radiative transfer module, to simultaneously simulate canopy solar-induced chlorophyll fluorescence (SIF) and gross primary productivity (GPP) and investigate their relationship across forest ecosystems. The model accurately simulates SIF and GPP across various temporal scales, revealing that the SIF-GPP relationship is site-dependent and influenced by canopy structure and leaf traits.

Objective

• To develop TECs-SIF, a terrestrial biosphere model that integrates a spectral invariant property-based radiative transfer model, to simultaneously simulate canopy SIF emissions and GPP.
• To investigate how the SIF-GPP relationship varies across different forest ecosystems and temporal scales.

Study Configuration

• Spatial Scale: Four AmeriFlux sites, including three evergreen needleleaf forests (Southern Old Black Spruce (CA-Obs), Delta Junction (US-xDJ), Niwot Ridge Forest (US-NR1)) and one deciduous broadleaf forest (University of Michigan Biological Station AmeriFlux site (US-UMB)).
• Temporal Scale: Hourly, daily, and monthly intervals.

Methodology and Data

• Models used: TECs-SIF (Terrestrial Ecosystem Carbon cycle simulator with SIF module), which integrates a spectral invariant property-based radiative transfer model across leaf and canopy scales.
• Data sources: Field observations from three evergreen needleleaf forest and one deciduous broadleaf forest AmeriFlux sites for calibration and validation of SIF and GPP simulations.

Main Results

• TECs-SIF accurately simulates SIF and GPP across various temporal scales.
  • Hourly: SIF (R² = 0.48–0.87, RMSE = 0.03–0.12 W⋅m⁻²⋅µm⁻¹⋅sr⁻¹); GPP (R² = 0.60–0.79, RMSE = 1.82–5.31 µmol⋅m⁻²⋅s⁻¹).
  • Daily: SIF (R² = 0.64–0.91, RMSE = 0.02–0.09 W⋅m⁻²⋅µm⁻¹⋅sr⁻¹); GPP (R² = 0.89–0.97, RMSE = 0.51–2.05 µmol⋅m⁻²⋅s⁻¹).
• The model captures nonlinear SIF-GPP relationships at hourly intervals and linear trends at daily and monthly scales.
• The SIF-GPP relationship is site-dependent across temporal scales, influenced by canopy structure (e.g., canopy index) and leaf traits.

Contributions

• Development of TECs-SIF, a novel terrestrial biosphere model that integrates a spectral invariant property-based radiative transfer model for simultaneous and accurate simulation of canopy SIF and GPP.
• Demonstration and quantification of the site-dependent nature of the SIF-GPP relationship across different forest ecosystems and temporal scales.
• Provides a promising tool to address spatiotemporal limitations of field and satellite observations and to explain variations in the SIF-GPP relationship.

Funding

Not specified in the provided text.

Citation

@article{Liu2025Unrevealing,
  author = {Liu, Haoran and Pierrat, Zoe and Dashti, Hamid and Chen, Min},
  title = {Unrevealing site-dependent relationship between solar-induced chlorophyll fluorescence and gross primary productivity using the terrestrial ecosystem carbon cycle simulator},
  journal = {Remote Sensing of Environment},
  year = {2025},
  doi = {10.1016/j.rse.2025.115052},
  url = {https://doi.org/10.1016/j.rse.2025.115052}
}