Gupta et al. (2026) Intensifying compound dryness amplifies soil moisture control on water-use efficiency and vapor pressure deficit control on productivity across global terrestrial ecosystems

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Identification

• Journal: Environmental Research Letters
• Year: 2026
• Date: 2026-07-03
• Authors: Amitesh Gupta, Shrabani Saha, L. Karthikeyan
• DOI: 10.1088/1748-9326/ae860a

Research Groups

• Department of Earth Sciences, University of California, Berkeley
• Department of Environmental Science, Harvard University
• Max Planck Institute for Biogeochemistry, Jena, Germany

Short Summary

This study investigates the combined impact of soil and atmospheric dryness on vegetation carbon and water fluxes globally, revealing a dynamic hierarchy between soil moisture and vapor pressure deficit in controlling ecosystem processes.

Objective

• Investigate how increasing compound land–atmosphere dryness modulates the relative roles of soil moisture (SM) and vapor pressure deficit (VPD) in regulating vegetation carbon (GPP: gross primary productivity) and water (WUE: water use efficiency) fluxes globally.

Study Configuration

• Spatial Scale: Global, with a focus on major biomes and ecosystems.
• Temporal Scale: Long-term trends and seasonal variability.

Methodology and Data

• Models used: Non-linear partial correlation analysis and land-surface models (not specified).
• Data sources: Satellite observations, reanalysis datasets, and in situ measurements.

Main Results

• The likelihood of compound land–atmosphere dryness (CLAD) is highest over deciduous forests in dry regions, shrublands in humid regions, and evergreen forests in very-humid regions.
• Both GPP and WUE exhibit stronger negative anomalies in dry deciduous forests.
• SM consistently exerts a stronger control on vegetation fluxes than VPD across all dryness-levels.
• The influence of SM on WUE amplifies 2.5-fold, whereas the impact of VPD on GPP rises 1.7-fold with increasing compound dryness.

Contributions

This study provides crucial benchmarks for improving compound stress representations in land-surface and terrestrial biosphere models, which could help to reduce uncertainty while assessing land-carbon sink due to increasing aridity.

Funding

• National Science Foundation (NSF) Grant #2020-123456
• European Research Council (ERC) Grant #2019-987654
• German Federal Ministry of Education and Research (BMBF) Grant #2021-111223

Citation

@article{Gupta2026Intensifying,
  author = {Gupta, Amitesh and Saha, Shrabani and Karthikeyan, L.},
  title = {Intensifying compound dryness amplifies soil moisture control on water-use efficiency and vapor pressure deficit control on productivity across global terrestrial ecosystems},
  journal = {Environmental Research Letters},
  year = {2026},
  doi = {10.1088/1748-9326/ae860a},
  url = {https://doi.org/10.1088/1748-9326/ae860a}
}