Mo et al. (2025) Time-lag effects of vegetation gross primary production response to the hydro-climate changes in humid and semi-humid areas of China

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2025
• Date: 2025-11-29
• Authors: Kangle Mo, Siru Wang, Zhen Cui, Lixin Chen, Ning Zhou, Hui G. Cheng, Yang Liu
• DOI: 10.1016/j.ejrh.2025.102969

Research Groups

• The National Key Laboratory of Water Disaster Prevention, Nanjing Hydraulic Research Institute, Nanjing, China
• Nanjing Hydraulic Research Institute, Nanjing, China
• School of Hydrology and Water Resources, Nanjing University of Information Science & Technology, Nanjing, China
• College of Soil and Water Conservation, Beijing Forestry University, Beijing, China

Short Summary

This study investigated the relationship between vegetation gross primary production (GPP) and hydro-climate factors (precipitation, temperature, basin water storage) in the humid and semi-humid Hanjiang River Basin, China. It revealed significant time-lag effects of hydrological factors on GPP (4 months for basin water storage, 5 months for precipitation), highlighting their long-term influence compared to the immediate response to temperature.

Objective

• To comprehensively understand how vegetation growth responds to climate and hydrological changes across different time scales in the Hanjiang River Basin.
• To evaluate the time-lag response of vegetation growth to hydro-climate factors, specifically determining the duration of these delays and the differential impact of each factor.

Study Configuration

• Spatial Scale: Hanjiang River Basin (HRB), a sub-basin of the Yangtze River Basin in central China, with a total area of 159,000 km². The study also analyzed upper and mid-lower sub-basins.
• Temporal Scale: 2001–2018 (18 years), analyzed on monthly, seasonal, and annual scales.

Methodology and Data

• Models used:
  • Water balance equation
  • Sen’s slope
  • Simple linear regression (Ordinary Least Squares, OLS)
  • Mann-Kendall (M-K) statistical test
  • Partial correlation analysis
  • Ridge regression analysis
  • Distributed Lag Model (DLM)
  • Kriging interpolation method
• Data sources:
  • Gross Primary Production (GPP): MODIS/Terra Vegetation Level-4 Production (MOD17A2H) version 6 datasets (8-day composite, 500 m resolution), resampled to monthly sums.
  • Meteorological data (precipitation, temperature, etc.): National Meteorological Information Center (NMIC) of the China Meteorological Administration (CMA) from 21 national basic meteorological stations (daily data, 2001–2018), interpolated to 500 m resolution.
  • Hydrological data (daily flow): “Hydrological Yearbook of the People’s Republic of China” from Huangjiagang and Huangzhuang stations (2001–2018).
  • Vegetation types data: “Spatial distribution data of ecosystem types in multiple periods in China”, Resource and Environmental Science Data Platform (1 km resolution, 2018).

Main Results

• The overall GPP in the Hanjiang River Basin showed a significant increasing trend from 2001 to 2018, with GPP increasing in 82.26 % of the basin area. The mean annual GPP was 1030.76 gC/m²/year in the upper basin and 910.17 gC/m²/year in the mid-lower basin.
• On an annual scale, GPP was positively correlated with temperature (T) and basin water storage (ΔS), but negatively correlated with precipitation (P).
• Temperature (T) exhibited a robust and dominant positive correlation with GPP across monthly, seasonal, and annual scales, with no obvious time-lag effect.
• Precipitation (P) showed a relatively strong positive correlation with GPP on a monthly scale, but a weak negative correlation on an annual scale, with a time-lag of 5 months for its maximum absolute partial correlation.
• Basin water storage (ΔS) manifested its influence on GPP on an annual scale with a positive correlation, and a significant time-lag of 4 months. This delayed effect was most pronounced in spring and winter.
• The impact of ΔS on GPP became more significant with prolonged lagged time and accumulated months, indicating persistent and enduring effects of hydrological conditions.

Contributions

• Revealed longer and more complex time-lag effects of GPP response to hydrological factors (4-5 months) in a humid/semi-humid basin, challenging previous findings often based on shorter time scales or different vegetation indices (e.g., NDVI).
• Highlighted the importance of considering cross-season effects and full annual periods in vegetation dynamics research, as opposed to solely focusing on growing seasons, which may underestimate hydrological influences.
• Demonstrated that even in humid and semi-humid areas, basin water storage can exert a long-term control on vegetation growth, with its significance amplified by delayed and cumulative effects.
• Provided insights into the distinct water use strategies of different vegetation types (forest/grassland vs. farmland) in response to varying hydro-climate factors across different time scales.
• Contributed to a deeper understanding of vegetation strategies under changing hydro-climate conditions and human hydrological regulation, offering scientific insights for regional water and carbon resource management.

Funding

• National Key Research and Development Program of China (No. 2023YFC3205501)
• National Natural Science Foundation of China (No.52121006, No.U2240223)
• Special Fund for Basic Research Operations of Central Public-interest Scientific Institutions (Y925004)

Citation

@article{Mo2025Timelag,
  author = {Mo, Kangle and Wang, Siru and Cui, Zhen and Chen, Lixin and Zhou, Ning and Cheng, Hui G. and Liu, Yang},
  title = {Time-lag effects of vegetation gross primary production response to the hydro-climate changes in humid and semi-humid areas of China},
  journal = {Journal of Hydrology Regional Studies},
  year = {2025},
  doi = {10.1016/j.ejrh.2025.102969},
  url = {https://doi.org/10.1016/j.ejrh.2025.102969}
}