Tian et al. (2026) Differential response of soil moisture in surface and root zones to climate and land use changes

Identification

• Journal: Agricultural Water Management
• Year: 2026
• Date: 2026-04-03
• Authors: Yukun Tian, Xudong Peng, Liang Wei, Zhuyu Zhang, Quanhou Dai
• DOI: 10.1016/j.agwat.2026.110333

Research Groups

• College of Forestry, Guizhou University, Guiyang, China
• Institute of Soil Erosion and Ecological Restoration, Guizhou University, Guiyang, China
• Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang, China

Short Summary

This study investigates the global dynamics and drivers of surface (0–10 cm) and root-zone (10–250 cm) soil moisture from 1982 to 2021, revealing significant regional differences and a stronger dominance of climate factors over land use/cover change (LUCC), particularly for root-zone soil moisture. It highlights that surface soil moisture is more sensitive to the coupling effects of LUCC and climate, while root-zone soil moisture is primarily controlled by long-term climatic conditions.

Objective

• To analyze the trends in soil moisture changes in different climate regions.
• To explore the dominant roles of climate and LUCC in different climate regions.
• To quantify the contributions of the dominant factors to surface soil moisture (SMsurf) and root-zone soil moisture (SMroot).

Study Configuration

• Spatial Scale: Global, with a spatial resolution of 0.25° × 0.25°.
• Temporal Scale: 1982 to 2021 (40 years).

Methodology and Data

• Models used:
  • Global Land Evaporation Amsterdam Model (GLEAM v3.6a) for soil moisture data generation.
  • Theil–Sen trend estimation, Mann–Kendall (MK) trend test for trend analysis.
  • Pearson correlation analysis for relationships between variables.
  • Variance decomposition for quantifying relative contributions.
  • Partial Least Squares Structural Equation Model (PLS-SEM) for identifying dominant climatic factors.
• Data sources:
  • Soil Moisture (SMsurf, SMroot): GLEAM v3.6a product (satellite microwave observations for SMsurf, multi-layer running water balance framework for SMroot).
  • Land Use/Cover Change (LUCC): European Space Agency's Land Cover product (ESA CCI).
  • Climate variables (Precipitation (PCP), Temperature (TMP), Solar Radiation (RAD)): GLDAS-2.1 dataset from NASA.

Main Results

• Significant regional differences in soil moisture (SM) dynamics were observed, with SMsurf generally higher than SMroot in humid and semi-humid regions, but the opposite in extremely arid regions.
• The greatest decline in SM was found in semi-arid and semi-humid regions, consistent with changes in precipitation, temperature, and solar radiation.
• Climate factors exert stronger dominance on SM variability than LUCC, especially for SMroot, which showed a 30.3% independent contribution from climate factors compared to 11.6% from LUCC.
• SMsurf is more sensitive to the coupling effect of LUCC and climate (11.9% interaction contribution) and LUCC (14.2% independent contribution).
• Decreasing precipitation was the main cause of SM decline in humid and semi-humid regions.
• Increasing temperature and solar radiation played increasingly important roles in arid and hyper-arid regions, with temperature becoming a key regulator of SMroot in hyper-arid regions.
• Land use transitions associated with forests and wetlands generally maintained higher moisture levels, while those involving bare land showed substantially lower values.
• Precipitation had a significant positive effect on both SMsurf (path coefficient: 0.557) and SMroot (path coefficient: 0.432), while temperature showed a significant negative effect on both layers (path coefficients: -0.333 and -0.422, respectively).

Contributions

• Provides a unified global comparison of surface and root-zone soil moisture dynamics across different climate zones under the same climate-LUCC framework.
• Quantifies the differential responses of SMsurf and SMroot to the coupling effects of LUCC and climate, advancing the mechanistic understanding of terrestrial water cycles.
• Highlights that SMsurf is more sensitive to LUCC and its interaction with climate, while SMroot exhibits greater persistence and sensitivity to long-term climatic influences.

Funding

• Guizhou Provincial Key Technology R&D Program (QKHZC [2023] YB104)
• Guizhou Provincial Basic Research Program (Natural Science) (QKHZD〔2026〕007)
• National Natural Science Foundation of China (NO. 42267054, 42007067)

Citation

@article{Tian2026Differential,
  author = {Tian, Yukun and Peng, Xudong and Wei, Liang and Zhang, Zhuyu and Dai, Quanhou},
  title = {Differential response of soil moisture in surface and root zones to climate and land use changes},
  journal = {Agricultural Water Management},
  year = {2026},
  doi = {10.1016/j.agwat.2026.110333},
  url = {https://doi.org/10.1016/j.agwat.2026.110333}
}