Shengqi et al. (2026) Vegetation Phenology Changes in China from 1982 to 2018 Increased Evapotranspiration

Identification

• Journal: Earth Systems and Environment
• Year: 2026
• Date: 2026-01-13
• Authors: Jian Shengqi, Kong Lilin, Dou Shentang, Yu Xin
• DOI: 10.1007/s41748-025-01008-z

Research Groups

• College of Water Conservancy and Transportation, Zhengzhou University, Zhengzhou, China
• Yellow River Institute of Hydraulic Research, Zhengzhou, China
• Yellow River Laboratory, Zhengzhou, China
• Engineering Technology Research Center of Intelligent Water Conservancy of Henan Province, Zhengzhou, China

Short Summary

This study quantified the contribution of vegetation phenological shifts to evapotranspiration (ET) changes across China from 1982 to 2018. It found that an extended growing season, driven by earlier spring onset and delayed autumn senescence, significantly increased ET, accounting for 7.53% of the total ET change, despite an overall slight national ET decrease.

Objective

• To extract long-term vegetation phenology parameters (Start of Growing Season, End of Growing Season, Growing Season Length) across China.
• To integrate dynamic phenology into an improved Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) ET model and evaluate its performance.
• To disentangle the relative contributions of climate change, land use/cover change (LUCC), and phenological shifts to ET variations across China.

Study Configuration

• Spatial Scale: China, covering nine major river basins (Southwest Basin, Pearl River Basin, Yangtze River Basin, Southeast Basin, Huaihe River Basin, Yellow River Basin, Haihe River Basin, Songhua and Liaohe River Basin, and Continental Basin). Data were standardized to a 0.1° spatial resolution.
• Temporal Scale: 1982 to 2018 (37 years). Data were standardized to a monthly temporal scale.

Methodology and Data

• Models used:
  • Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model, improved by incorporating dynamic optimum temperature for plant growth (T_opt) based on the average temperature of the growing season.
  • TIMESAT software for vegetation phenology extraction, utilizing the Savitzky-Golay filter and a dynamic threshold method (30% of annual maximum NDVI).
  • Sen’s slope estimator and Mann-Kendall (M-K) statistical test for trend analysis and significance assessment.
• Data sources:
  • Satellite remote sensing: GIMMS NDVI3g (1982–2000), MODIS NDVI (2001–2018), GLASS albedo and land cover products.
  • Observation: In-situ meteorological measurements and evapotranspiration (ET) observations from 8 flux tower sites (CBF, DXG, QYF, YCA, HBG, BNF, DHF, NMG) from the Nation Science and Technology Infrastructure.
  • Reanalysis: Gridded meteorological forcing data (CMFD).

Main Results

• Vegetation Phenology Trends (1982–2018):
  • The Start of Growing Season (SOS) advanced by 0.12 days per year nationally, with significant advances in 37% of the country.
  • The End of Growing Season (EOS) delayed by 0.07 days per year nationally, with significant delays in 23% of the country.
  • The Growing Season Length (GSL) lengthened by 0.18 days per year nationally, with significant lengthening in 26.5% of the country.
• Evapotranspiration (ET) Trends (1982–2018):
  • The national mean annual ET was 382.23 mm per year.
  • National mean ET showed a slight decreasing trend of -0.21 mm per year.
  • Approximately 46% of China experienced an increase in mean annual ET, with 22% showing significant increases.
  • ET temporal patterns in most basins exhibited turning points around 1997 or 2003, attributed to climatic shifts and ecological restoration programs.
• Contribution of Vegetation Phenology to ET:
  • Phenological changes contributed an average of 3.82 mm per year to ET increase across China.
  • This contribution accounted for an average of 7.53% of the total ET variation nationally.
  • Regional contributions varied, reaching up to 10.95% in basins like the Continental Basin (CB) and Southeast Basin (SEB).
• Model Performance: The improved PT-JPL model with dynamic T_opt reduced ET simulation errors by 20–40% compared to the original version, achieving an average R² of 0.78, RMSE of 17.81 mm·month⁻¹, and PBIAS of -11.94% across 8 flux sites.

Contributions

• Provided the first explicit quantification of the relative contribution of vegetation phenology as an independent driver to evapotranspiration variations at a national scale in China.
• Enhanced the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model by integrating dynamic phenological parameters, specifically by using the average temperature of the growing season for the optimum plant growth temperature (T_opt), leading to improved ET simulation accuracy.
• Highlighted the non-negligible role of vegetation phenology (7.53% average contribution) in regulating terrestrial water fluxes under climate change, extending the understanding beyond previous studies that primarily focused on land use/cover change or climate drivers.
• Offered scientific guidance for ecosystem and water resource management in China, emphasizing the importance of incorporating regional phenological trends into adaptive irrigation planning, vegetation restoration, and land-use optimization strategies.

Funding

• National Natural Science Foundation of China (U2443219)
• Science found for distinguished young scholars of Henan Province (232300421017)
• Henan Province Outstanding Young Scholars Fund (252300421195)
• Qian Kehe Zhicheng [2023] Yiban 206
• Qian Kehe Zhicheng [2024] Yiban 130

Citation

@article{Shengqi2026Vegetation,
  author = {Shengqi, Jian and Lilin, Kong and Shentang, Dou and Xin, Yu},
  title = {Vegetation Phenology Changes in China from 1982 to 2018 Increased Evapotranspiration},
  journal = {Earth Systems and Environment},
  year = {2026},
  doi = {10.1007/s41748-025-01008-z},
  url = {https://doi.org/10.1007/s41748-025-01008-z}
}