Wang et al. (2026) Rising dominance of vapor pressure deficit and carbon dioxide in vegetation drought on the Loess plateau

Identification

• Journal: Agricultural Water Management
• Year: 2026
• Date: 2026-08-12
• Authors: Ai Wang, Xuerui Gao, Zeyu Zhou, Yalong Li, Xining Zhao
• DOI: 10.1016/j.agwat.2026.110694

Research Groups

• Agricultural Water Conservancy Department, Changjiang River Scientific Research Institute (Wuhan, Hubei Province)
• Institute of Soil and Water Conservation, Northwest A&F University (Yangling, Shaanxi Province)
• College of Resources and Environment, Yangtze University (Wuhan, Hubei Province)
• College of Water Resources Science and Engineering, Taiyuan University of Technology (Taiyuan, Shanxi Province)

Short Summary

This study explores the drivers of vegetation drought on the Loess Plateau using a Standardized Vegetation Water Deficit Index (SVWDI) and machine learning-based attribution. The results show that precipitation-dominated vegetation drought in the early stage of the Grain for Green Project shifted to vapor pressure deficit (VPD) and carbon dioxide (CO2)-driven drought in recent years.

Objective

• Investigate the spatiotemporal evolution trends of vegetation drought on the Loess Plateau during 1991–2020.
• Quantitatively detect and characterize a potential historical shift in the dominant drivers of vegetation drought over the past three decades (1991–2020).
• Elucidate how large-scale climatic oscillations modulate the spatiotemporal patterns of regional vegetation drought.

Study Configuration

• Spatial Scale: The study focuses on the Loess Plateau, a semi-humid to semi-arid transitional climate region in China.
• Temporal Scale: The study period is from 1991 to 2020, divided into three sub-periods: T1 (1991–2000), T2 (2001–2010), and T3 (2011–2020).

Methodology and Data

• Models used: Standardized Vegetation Water Deficit Index (SVWDI) and Random Forest regression model.
• Data sources: Meteorological data, CO2 data, vegetation parameters, soil parameters, and remote sensing data from various sources.

Main Results

• The results show that the area proportion of all drought grades decreased in the order of T1 > T2 > T3, indicating a continuous mitigation of vegetation drought in the region.
• The importance ranking of climatic factors affecting vegetation drought on the Loess Plateau during this period was: P > VPD > CO₂ > WS > T > Rn.
• Vapor pressure deficit (VPD) and carbon dioxide (CO2) became the dominant driving factors of vegetation drought in recent years.

Contributions

• This study provides a quantitative understanding of the drivers of vegetation drought on the Loess Plateau, highlighting the increasing importance of plant physiological processes in vegetation drought.
• The results suggest that future ecological assessment and management should move beyond a purely hydrological perspective toward a plant physiological–hydrological coupling framework.

Funding

• This research was funded by the National Natural Science Foundation of China (Grant No. 51979224) and the Key Research Program of the Chinese Academy of Sciences (Grant No. KFZD-BR-2021).

Citation

@article{Wang2026Rising,
  author = {Wang, Ai and Gao, Xuerui and Zhou, Zeyu and Gao, Xuerui and Li, Yalong and Zhao, Xining},
  title = {Rising dominance of vapor pressure deficit and carbon dioxide in vegetation drought on the Loess plateau},
  journal = {Agricultural Water Management},
  year = {2026},
  doi = {10.1016/j.agwat.2026.110694},
  url = {https://doi.org/10.1016/j.agwat.2026.110694}
}