Liu et al. (2026) Controls on ecosystem groundwater use efficiency: insights from forest ecosystems in the northern hemisphere

Identification

• Journal: Energy Nexus
• Year: 2026
• Date: 2026-09-10
• Authors: Xinyi Liu, Quan Lai, Shan Yin, Rihe Gao
• DOI: 10.1016/j.nexus.2026.100814

Research Groups

• College of Public Administration, Inner Mongolia University of Finance and Economics
• College of Geographical Science, Inner Mongolia Normal University
• Key Laboratory of Mongolian Plateau Geographical Research, Inner Mongolia Autonomous Region

Short Summary

This study evaluates groundwater use efficiency (GWUE) in northern hemisphere forests using remote sensing-derived gross primary productivity (GPP) and groundwater storage (GWS) data. The results show that GWUE generally increased from 2000 to 2024, with higher values in humid tropical and subtropical forests and lower values in dry temperate and cold boreal forests.

Objective

• Investigate the relationship between ecosystem carbon assimilation and groundwater dynamics across forest types and climate zones.
• Quantify the sensitivity of forest carbon uptake to groundwater variability at larger spatial scales.

Study Configuration

• Spatial Scale: Northern Hemisphere, with a focus on forest ecosystems.
• Temporal Scale: 2000-2024, with annual data used for analysis.

Methodology and Data

• Models used: LightGBM machine learning model for regression tasks.
• Data sources:
  • GOSIF dataset for gross primary productivity (GPP)
  • ERA-5 reanalysis dataset for air temperature, precipitation, and vapor pressure deficit
  • CRU VPD dataset for vapor pressure deficit
  • GLDAS-2 dataset for groundwater storage
  • FLUXNET2015 dataset for eddy covariance flux measurements

Main Results

• GWUE generally increased from 2000 to 2024.
• Higher values of GWUE were found in humid tropical and subtropical forests, while lower values were observed in dry temperate and cold boreal forests.
• The highest GWUE was observed in evergreen broad-leaved forests (EBF), followed by deciduous broad-leaved forests (DBF) and mixed forests (MF).
• Lower GWUE values were found in evergreen needle-leaved forests (ENF) and deciduous needle-leaved forests (DNF).

Contributions

• This study provides a hemispheric-scale comparative assessment of the spatial distribution, long-term dynamics, and environmental associations of GWUE across major forest types and hydroclimatic zones.
• The results can inform forest and groundwater management by identifying areas with strong coupling between ecosystem carbon assimilation and groundwater dynamics.

Funding

• This research was funded by the National Natural Science Foundation of China (Grant No. 42171051) and the Inner Mongolia Autonomous Region Science and Technology Innovation Fund (Grant No. 2022HJ0003).

Citation

@article{Liu2026Controls,
  author = {Liu, Xinyi and Lai, Quan and Yin, Shan and Gao, Rihe},
  title = {Controls on ecosystem groundwater use efficiency: insights from forest ecosystems in the northern hemisphere},
  journal = {Energy Nexus},
  year = {2026},
  doi = {10.1016/j.nexus.2026.100814},
  url = {https://doi.org/10.1016/j.nexus.2026.100814}
}