Xie et al. (2025) Vegetation Transpiration Drives Root-Zone Soil Moisture Depletion in Subtropical Humid Regions: Evidence from GLDAS Catchment Simulations in Fujian Province

Identification

• Journal: Atmosphere
• Year: 2025
• Date: 2025-10-13
• Authors: Yali Wang, Dina Huang, Xingwei Chen, Haijun Deng
• DOI: 10.3390/atmos16101180

Research Groups

• School of Geographical Sciences, Fujian Normal University, Fuzhou, China
• National Demonstration Center for Experimental Geography Education, Fujian Normal University, Fuzhou, China
• Fujian Provincial Engineering Research Centre for Monitoring and Assessing Terrestrial Disasters, School of Geographical Sciences, Fujian Normal University, Fuzhou, China
• Key Laboratory of Humid Subtropical Eco-Geographical Processes of Ministry of Education, School of Geographical Sciences, Fujian Normal University, Fuzhou, China

Short Summary

This study investigates the spatiotemporal patterns and interactions between vegetation transpiration and root-zone soil moisture in Fujian Province using GLDAS Catchment data from 2004 to 2023. It reveals a strong negative correlation where transpiration primarily drives soil moisture depletion with a 1- to 2-year lead time.

Objective

• To analyze the spatiotemporal dynamics and interactive characteristics of vegetation transpiration and root-zone soil moisture, and to reveal the response mechanisms linking these two variables in subtropical humid regions, specifically Fujian Province.

Study Configuration

• Spatial Scale: Fujian Province, China (23°31′ to 28°18′ N latitude and 115°50′ to 120°43′ E longitude). Data resolution: 0.25° × 0.25°.
• Temporal Scale: Daily data from 1 January 2004 to 31 December 2023 (20 years), analyzed seasonally and interannually.

Methodology and Data

• Models used: Global Land Data Assimilation System (GLDAS) Catchment Land Surface Model (CLSM).
• Data sources:
  • GLDAS CLSM: Root-zone soil moisture and vegetation transpiration data.
  • National Tibetan Plateau Data Center: 1 km resolution monthly precipitation and mean air temperature datasets for China (1901–2023).
  • MODIS vegetation indices and SMAP soil moisture observations (integrated into GLDAS CLSM optimization).
• Analytical methods: Mann–Kendall (M-K) trend test, Cross-Wavelet Transform (XWT), Singular Value Decomposition (SVD).

Main Results

• Vegetation transpiration in Fujian Province showed an overall declining trend from 2004 to 2023 at a rate of −5.58 mm/yr, with a decrease from 2004–2016 (−13.43 mm/yr) followed by an increase from 2016–2023 (10.93 mm/yr). Spatially, an overall decline was observed.
• Root-zone soil moisture exhibited an overall increasing trend from 2004 to 2023 at a rate of 0.52 mm/yr, with an increase from 2004–2016 (2.25 mm/yr) followed by a decrease from 2016–2023 (−2.55 mm/yr). Spatially, it showed overall growth with significant heterogeneity.
• A strong negative correlation was found between vegetation transpiration and root-zone soil moisture across most of the study area, particularly pronounced in summer and autumn (correlation coefficients predominantly between −0.8 and −1.0).
• Vegetation transpiration strongly influenced soil moisture, with increases (or decreases) in transpiration corresponding to decreases (or increases) in soil moisture, indicating a dominant role of transpiration in soil water consumption.
• Transpiration changes preceded those in soil moisture, and a significant resonance relationship with a 1- to 2-year cycle was identified in the time–frequency domain.
• SVD analysis revealed that the first mode explained 96.21% of the squared covariance fraction, with a temporal correlation coefficient of 0.86 between the two fields, indicating strong synchronous temporal evolution.

Contributions

• Provides novel insights into the vegetation–soil moisture dynamics in humid subtropical regions, addressing a research gap compared to more studied arid/semi-arid ecosystems.
• Utilizes advanced time–frequency analysis (cross-wavelet transform) and Singular Value Decomposition to elucidate multi-scale relationships and dominant driving directions between eco-hydrological variables in a complex subtropical forest ecosystem.
• Highlights the pivotal role of vegetation transpiration as the primary driver of root-zone soil moisture depletion in humid subtropical regions.
• Offers a scientific basis for formulating vegetation restoration strategies, adaptive climate management, and developing early-warning mechanisms for eco-hydrological risks in southeastern China.

Funding

• Projects for National Natural Science Foundation of China (U22A20554 and 42471038)
• Water Conservancy Science and Technology Project of Fujian, China (MSK202436)
• Natural Science Foundation of Fujian Province (2023J01285)

Citation

@article{Xie2025Vegetation,
  author = {Xie, Yudie and Wang, Yali and Huang, Dina and Chen, Xingwei and Deng, Haijun},
  title = {Vegetation Transpiration Drives Root-Zone Soil Moisture Depletion in Subtropical Humid Regions: Evidence from GLDAS Catchment Simulations in Fujian Province},
  journal = {Atmosphere},
  year = {2025},
  doi = {10.3390/atmos16101180},
  url = {https://doi.org/10.3390/atmos16101180}
}