Kelly et al. (2026) Evaluating vegetation indices for monitoring drought and post-drought declines in European forest productivity

Identification

• Journal: Biogeosciences
• Year: 2026
• Date: 2026-09-18
• Authors: Julia Kelly, Tim Schacherl, Lars Eklundh, Hongxiao Jin, Anne Klosterhalfen, Alexander Knohl, Natascha Kljun
• DOI: 10.5194/bg-23-6557-2026

Research Groups

• Department of Earth and Environmental Sciences, Lund University, Sweden
• Bioclimatology, University of Göttingen, Germany
• Centre of Biodiversity and Sustainable Land Use, University of Göttingen, Germany

Short Summary

This study evaluates the ability of 12 MODIS variables to capture drought-induced reductions in forest gross primary productivity (GPP) across Europe. The results show that land surface temperature was the only variable that consistently responded to drought, while other vegetation indices showed varying responses.

Objective

• Investigate the relationships between forest physiology and satellite-derived vegetation indices during drought events.
• Quantify the time lags between drought start, GPP, and VI response in forests across Europe.

Study Configuration

• Spatial Scale: Continental scale (Europe)
• Temporal Scale: Daily to annual resolution

Methodology and Data

• Models used: MODIS satellite variables (12 variables)
• Data sources: MODIS satellite data, FLUXNET eddy covariance data, ICOS ETC L2 Archive, and ICOS Warm Winter 2020 products

Main Results

• Land surface temperature was the only variable that consistently showed significant changes between drought and non-drought periods.
• Other vegetation indices (e.g., NDVI, EVI) showed varying responses to drought, with some responding before GPP and others after.
• The time lags between drought start, GPP, and VI response varied among indices and forest types.

Contributions

• This study provides new insights into the relationships between forest physiology and satellite-derived vegetation indices during drought events.
• The results highlight the importance of considering temporal variability in vegetation indices when modeling drought impacts on forest productivity.

Funding

• Not specified

Citation

@article{Kelly2026Evaluating,
  author = {Kelly, Julia and Schacherl, Tim and Eklundh, Lars and Jin, Hongxiao and Klosterhalfen, Anne and Knohl, Alexander and Kljun, Natascha},
  title = {Evaluating vegetation indices for monitoring drought and post-drought declines in European forest productivity},
  journal = {Biogeosciences},
  year = {2026},
  doi = {10.5194/bg-23-6557-2026},
  url = {https://doi.org/10.5194/bg-23-6557-2026}
}