Geng et al. (2025) Widespread decline of gross primary productivity due to compound heat and drought in the Wei river Basin, China

Identification

• Journal: Theoretical and Applied Climatology
• Year: 2025
• Date: 2025-12-01
• Authors: Guangpo Geng, Ruolin Zheng, Tiantian Deng, Lei Zhang, Yousheng Wang, Zuxin He
• DOI: 10.1007/s00704-025-05945-7

Research Groups

• College of Geomatics, Xi’an University of Science and Technology, Xi’an, China
• China Institute of Water Resources and Hydropower Research, Beijing, China

Short Summary

This study investigates the impact of compound heat and drought on Gross Primary Productivity (GPP) in the arid and semi-arid Wei River Basin, China, revealing that compound events significantly increase GPP decline, with grassland and cultivated vegetation being most vulnerable.

Objective

• Analyze the probability of vegetation productivity decline under single heat or drought conditions.
• Quantify the probability of vegetation productivity decline under compound heat and drought conditions.
• Identify typical compound heat and drought events (CHDEs) and reveal vegetation responses to these events.

Study Configuration

• Spatial Scale: Wei River Basin (104°00′–110°20′E, 33°40′–37°30′N), covering an area of 134,700 square kilometers. Data were resampled to an 8 kilometer spatial resolution.
• Temporal Scale: 1982–2020 (39 years). Data were aggregated to a monthly temporal scale.

Methodology and Data

• Models used:
  • Meta-Gaussian model (for quantifying the probability of GPP decline)
  • Linear regression model (for GPP data reconstruction)
• Data sources:
  • Meteorological data: Monthly maximum temperature and precipitation data from the National Earth System Science Data Center (http://www.geodata.cn/), 0.0083333° spatial resolution, 1980-2020.
  • Vegetation remote sensing data (GPP): GLASS GPP data (1982–2018, 8-day temporal, 0.05° spatial resolution) and MODIS MOD17A2H data (8-day temporal, 500 meter spatial resolution), unified to 1982-2020.
  • Irrigation data: 2016 dataset of irrigated farmland distribution in China (http://www.nesdc.org.cn/sdo/detail?id=6189ebe17e2817667e3c7d97), 500 meter spatial resolution.
  • Vegetation type data: Resource and Environmental Science Data Center of the Chinese Academy of Sciences (https://www.resdc.cn/).
  • Indices calculated: Standardized Temperature Index (STI), Standardized Precipitation Index (SPI), Standardized Gross Primary Productivity (SGPP).

Main Results

• Under mild, moderate, severe, and extreme heat conditions, the average probabilities of GPP decline were 44%, 47%, 51%, and 60%, respectively.
• Under mild, moderate, severe, and extreme drought conditions, the average probabilities of GPP decline were 63%, 70%, 74%, and 80%, respectively, indicating drought posed a greater risk than heat.
• Under mild, moderate, severe, and extreme compound heat and drought conditions, the average probabilities of GPP decline were 63%, 71%, 73%, and 90%, respectively, significantly increasing compared to single events.
• A typical compound heat and drought event from May to October 1997 resulted in GPP levels consistently below normal, with the largest loss of 31.03% occurring in August.
• Grassland and cultivated vegetation experienced the most significant GPP declines (23.6% and 19.74%, respectively) during the typical CHDE, while broadleaf forest and shrubland showed declines under 9%.
• GPP in irrigated crops declined more than in rainfed areas during the 1997 CHDE, suggesting irrigation may not fully mitigate the effects of extreme compound events.

Contributions

• Addresses a research gap by focusing on vegetation responses to compound heat and drought in arid and semi-arid regions, which are often overlooked compared to humid areas.
• Integrates both long-term compound heat and drought sequence analysis with a detailed assessment of a specific, typical compound event.
• Provides a dual-scale analytical framework that transitions from broad-scale assessments to localized investigations, offering a deeper understanding of ecosystem responses to both persistent climatic stress and acute extreme events.
• Offers a scientific foundation for risk assessment, climate adaptation strategies, and the protection of regional carbon sink functions in vulnerable arid and semi-arid ecosystems.

Funding

• National Natural Science Foundation of China (Grant number: 41807503)

Citation

@article{Geng2025Widespread,
  author = {Geng, Guangpo and Zheng, Ruolin and Deng, Tiantian and Zhang, Lei and Wang, Yousheng and He, Zuxin},
  title = {Widespread decline of gross primary productivity due to compound heat and drought in the Wei river Basin, China},
  journal = {Theoretical and Applied Climatology},
  year = {2025},
  doi = {10.1007/s00704-025-05945-7},
  url = {https://doi.org/10.1007/s00704-025-05945-7}
}