Tang et al. (2026) Fast response of satellite fluorescence-derived plant physiology to drought stress

Identification

• Journal: Nature Communications
• Year: 2026
• Date: 2026-02-27
• Authors: Zhi Tang, Diego G. Miralles, Xiaoyan Dai, Wouter H. Maes
• DOI: 10.1038/s41467-026-70076-0

Research Groups

• UAV Research Centre, Department of Plants and Crops, Ghent University, Ghent, Belgium
• School of Geographical Science, East China Normal University, Shanghai, China
• Hydro-Climate Extremes Lab (H-CEL), Ghent University, Ghent, Belgium
• Forest and Agricultural Biotechnology (FABI), Department of Plant and Soil Sciences, University of Pretoria, South Africa

Short Summary

This study globally disentangles the sequence and drivers of vegetation physiological and structural responses to drought using satellite data. It reveals that satellite fluorescence-derived plant physiology responds to drought within approximately 3 days, significantly faster than structural changes which emerge after approximately 12 days.

Objective

• To globally disentangle the sequence and related factors of vegetation physiological and structural responses to drought.
• To explore the response times of global vegetation physiology, greenness, and structure to drought stress at a daily scale.
• To simultaneously explore the effects of soil and atmospheric drought and leverage vegetation physiological indicators (SIFyield) for detecting earlier vegetation responses not reflected by traditional vegetation indices.

Study Configuration

• Spatial Scale: Global, with data resampled to a 0.25° spatial resolution.
• Temporal Scale: Daily, covering the period from 1 May 2018 to 31 December 2022 (5 years).

Methodology and Data

• Models used: Global Land Evaporation Amsterdam Model (GLEAM) v3.7b (for Evaporative Stress Index (ESI), surface soil moisture (SM), root zone SM), ERA5-Land (alternative SM data).
• Data sources:
  • Satellite Observations:
    • TROPOspheric Monitoring Instrument (TROPOMI) onboard Sentinel-5 Precursor: Daily Solar-Induced Chlorophyll Fluorescence (SIF) at 743 nanometres (nm).
    • Moderate Resolution Imaging Spectroradiometer (MODIS) MCD15A3H: Leaf Area Index (LAI) and fraction of absorbed Photosynthetically Active Radiation (fPAR).
    • MODIS MCD43C4: Enhanced Vegetation Index (EVI) and Near-Infrared Reflectance of Vegetation (NIRv).
    • Clouds and the Earth’s Radiant Energy System (CERES) SYN1deg Ed4.1: Photosynthetically Active Radiation (PAR).
    • Atmospheric Infrared Sounder (AIRS): Near-surface air temperature (AT) and relative humidity (RH).
  • Derived Metrics: SIF/PAR, SIF/APAR (proxy for SIFyield), Vapor Pressure Deficit (VPD) calculated from AT and RH in pascals (Pa).
  • Ancillary Data: GlobSnow (Snow Water Equivalent (SWE)), MODIS MCD12C1 (land cover), Köppen-Geiger climate classification maps, Global Aridity Index and Potential Evapotranspiration Database.
  • Drought Identification: ESI anomalies were used to identify the most severe drought events.
  • Response Time Calculation: Cross-correlations between vegetation index anomalies and drought indicator anomalies (SM, VPD) were calculated over a lag window of -5 to +31 days.

Main Results

• Approximately 74% of global vegetated areas experienced at least one drought event lasting over 30 days during the 5-year study period.
• Solar-induced chlorophyll fluorescence normalized by absorbed photosynthetically active radiation (SIF/APAR), a proxy for vegetation physiology, exhibited the most rapid response to drought, with a mode of approximately 3 days to Vapor Pressure Deficit (VPD) and approximately 5 days to Soil Moisture (SM).
• Leaf Area Index (LAI), a proxy for vegetation structure, showed the most delayed response, with a mode of approximately 13 days to VPD and approximately 12 days to SM.
• The response times of SIF/PAR and other optical vegetation indices (EVI, NIRv, fPAR) were more similar to those of LAI, indicating their stronger influence by vegetation canopy structure and greenness.
• Physiological responses (SIF/APAR) were more temporally aligned with changes in VPD, while structural changes (LAI) coincided more with SM dynamics.
• The distinct timing contrast between physiological and structural responses was most pronounced in humid regions.
• The shortest response times for vegetation physiology (SIF/APAR) were observed in intertropical regions.
• Vegetation physiology response time decreased along the aridity gradient from dry to wet regions.

Contributions

• Provides satellite-based evidence for the decoupling of physiological and morphological responses to water stress at the ecosystem scale.
• Advances the mechanistic understanding of vegetation drought responses across the continuum from rapid physiological adjustments to slower structural modifications.
• Demonstrates that SIF/APAR serves as a robust proxy for ecosystem-level vegetation physiology, capturing early drought stress signals that are not detectable by traditional optical remote sensing indices.
• Offers crucial insights into global vegetation–drought interactions, with implications for improved climate prediction and understanding of carbon and water balances.

Funding

• European Research Council (ERC) through the HEAT Consolidator Grant (101088405)
• China Scholarship Council (202306140085)
• Research Foundation – Flanders (FWO)
• Flemish government (for VSC computing resources)

Citation

@article{Tang2026Fast,
  author = {Tang, Zhi and Miralles, Diego G. and Dai, Xiaoyan and Maes, Wouter H.},
  title = {Fast response of satellite fluorescence-derived plant physiology to drought stress},
  journal = {Nature Communications},
  year = {2026},
  doi = {10.1038/s41467-026-70076-0},
  url = {https://doi.org/10.1038/s41467-026-70076-0}
}