Batungwanayo et al. (2026) Compound drought stressors drive vegetation decline in the African Great Lakes region: a multiscale causal analysis

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Identification

• Journal: Environmental Research Climate
• Year: 2026
• Date: 2026-03-03
• Authors: Pacifique Batungwanayo, Marnik Vanclooster, Athanase Nkunzimana
• DOI: 10.1088/2752-5295/ae4cc1

Research Groups

Not specified in the provided abstract.

Short Summary

This study identifies the direct drivers of compound drought impacts on vegetation productivity in the African Great Lakes Region (AGLR) over 25 years, revealing that combined vapor pressure deficit (VPD) and soil moisture (SM) deficits are the primary causal factors, leading to a 15% greater greenness decline in croplands and shrublands compared to forests.

Objective

• To identify the direct drivers and causal pathways of compound drought impacts on vegetation productivity across the African Great Lakes Region (AGLR).

Study Configuration

• Spatial Scale: African Great Lakes Region (AGLR).
• Temporal Scale: 25-year analysis (2000–2024).

Methodology and Data

• Models used: Wavelet-based causal discovery (PCMCI) framework.
• Data sources: Satellite-derived vegetation indices (Normalized Difference Vegetation Index - NDVI), hydroclimatic variables (precipitation, temperature, soil moisture (SM), vapor pressure deficit (VPD)), and teleconnections.

Main Results

• Croplands and shrublands experienced a 15% greater decline in greenness (NDVI) compared to forests during major climate events, such as the 2015-16 El Niño and the 2023-24 positive Indian Ocean Dipole.
• Severe vegetation stress in the AGLR is not primarily driven by precipitation or temperature anomalies alone.
• Vegetation stress is causally linked to the combined influence of coinciding vapor pressure deficit (VPD) and soil moisture (SM) deficits.
• The combined effects of high atmospheric dryness (VPD) and low soil moisture (SM) are linked to significant vegetation productivity loss across the region.

Contributions

• Provides clear, data-driven evidence for the causal link between compound VPD-SM deficits and significant vegetation productivity loss in the AGLR, moving beyond correlative studies.
• Introduces a causal discovery framework (PCMCI) to identify direct drivers of vegetation stress in data-scarce regions.
• Offers a scientific foundation for integrating compound VPD-SM metrics into regional drought early-warning systems to improve the lead time and accuracy of food security interventions.

Funding

Not specified in the provided abstract.

Citation

@article{Batungwanayo2026Compound,
  author = {Batungwanayo, Pacifique and Vanclooster, Marnik and Nkunzimana, Athanase},
  title = {Compound drought stressors drive vegetation decline in the African Great Lakes region: a multiscale causal analysis},
  journal = {Environmental Research Climate},
  year = {2026},
  doi = {10.1088/2752-5295/ae4cc1},
  url = {https://doi.org/10.1088/2752-5295/ae4cc1}
}