Bai et al. (2026) The quantity of soil moisture replenishment rather than soil water content controls larch growth in semi-arid mountainous areas, Northwest China

Identification

• Journal: Agricultural and Forest Meteorology
• Year: 2026
• Date: 2026-04-11
• Authors: Yushi Bai, Pengtao Yu, Yanfang Wan, Dongsheng Guo, Shiji Yang, Zhiwei Zhang, Yanhui Wang, Zebin Liu
• DOI: 10.1016/j.agrformet.2026.111178

Research Groups

• Key Laboratory of National Forestry and Grassland Administration on Forest Ecosystem Protection and Restoration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing 100091, China
• Ningxia Liupan Mountains Forest Ecosystem Observation and Research Station, Guyuan 756400, China
• College of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China
• College of Forestry, Shanxi Agricultural University, Jinzhong 030801, China

Short Summary

This study investigated the control of larch growth by soil moisture replenishment (SMR) versus soil water content in semi-arid mountainous areas of Northwest China, finding that SMR is a primary determinant, especially for stem growth, and significantly influences water use efficiency. The findings suggest SMR should be a key indicator for ecological restoration in these water-limited regions.

Objective

• To quantify the effects of soil moisture replenishment (SMR) driven by hillslope water transport on larch growth, stem diameter, leaf area, and water use efficiency in a semi-arid mountainous area.

Study Configuration

• Spatial Scale: A larch hillslope in semi-arid mountainous areas, Northwest China.
• Temporal Scale: Growing seasons (May to October) from 2021 to 2023.

Methodology and Data

• Models used: Not applicable (observational study).
• Data sources: Monitoring of tree stem diameter, leaf area, meteorological conditions, and soil moisture.

Main Results

• The promotion effect of soil moisture replenishment (SMR) on larch growth during the growing period (May to August) varied substantially. In relatively wet years, it ranged from 0.72 to 3.37 for leaf area index (LAI) and -0.01 to 0.23 cubic centimetres per square metre (cm³/m²) for basal area increment (BAI). In summer dry years, it ranged from 0.82 to 2.47 for LAI and -0.03 to 0.10 cm³/m² for BAI.
• The promotion effect of SMR was more pronounced in stem growth than in leaf expansion.
• SMR significantly altered water use efficiency (WUE), exhibiting a logistic relationship where WUE increased rapidly by 0.02 WUE per 10 millimetres (mm) of SMR when the annual SMR ranged between 75 mm and 200 mm.
• Drier summers, characteristic of climate change, are expected to reduce SMR during the growing period, further detrimentally impacting tree growth.

Contributions

• Identifies soil moisture replenishment (SMR) as a more critical determinant of larch growth than soil water content in semi-arid mountainous areas, addressing a previously overlooked factor related to hillslope water transport.
• Provides quantitative relationships between SMR and key tree growth indicators (LAI, BAI) and water use efficiency (WUE).
• Proposes SMR as a primary indicator for site selection and prioritisation of ecological restoration efforts in semi-arid regions, specifically suggesting areas with annual SMR exceeding 200 mm.

Funding

• Not specified in the provided text.

Citation

@article{Bai2026quantity,
  author = {Bai, Yushi and Yu, Pengtao and Wan, Yanfang and Guo, Dongsheng and Yang, Shiji and Zhang, Zhiwei and Wang, Yanhui and Liu, Zebin},
  title = {The quantity of soil moisture replenishment rather than soil water content controls larch growth in semi-arid mountainous areas, Northwest China},
  journal = {Agricultural and Forest Meteorology},
  year = {2026},
  doi = {10.1016/j.agrformet.2026.111178},
  url = {https://doi.org/10.1016/j.agrformet.2026.111178}
}