Ren et al. (2025) Two decades of vegetation productivity change shaped by water availability and human activity in northern China’s arid–semi-arid transition

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2025
• Date: 2025-11-25
• Authors: Xiongfei Ren, Xinying Li, Yue Xin, Zhaoxia Ma, Jianying Guo, Tianming Gao, Le Zhao, Le Zhao, Liqing Zhao, Liqing Zhao, Zhenyu Yao
• DOI: 10.1016/j.ejrh.2025.102970

Research Groups

• Yinshanbeilu Grassland Eco-hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research, Beijing, China
• Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, Inner Mongolia University, Hohhot, China
• Observation and Research Station for the Typical Steppe Ecosystem of the Ministry of Education, Inner Mongolia University, Hohhot, China
• School of Ecology and Environment, Inner Mongolia University, Hohhot, China
• Beijiao Park, Hohhot, China
• The Water Affairs Bureau of Tumd Left Banner, Hohhot, China

Short Summary

This study analyzed vegetation net primary productivity (NPP) changes in northern China's arid-semi-arid transition zone from 2001 to 2020, revealing an overall NPP increase primarily driven by human activities (67.84%) and moisture-related climate factors, though a low Hurst index suggests these gains may not persist.

Objective

• To examine the temporal and spatial trends of Net Primary Productivity (NPP) across the Northern Foothills of the Yinshan Mountains (NFYM) from 2001 to 2020.
• To identify the single and interactive mechanisms influencing the spatiotemporal distribution of NPP.
• To quantify the relative contribution of climate factors and human activities to changes in NPP.

Study Configuration

• Spatial Scale: Northern foothills of the Yinshan Mountains in Inner Mongolia (NFYM), China, an arid-semi-arid transition zone spanning approximately 160,000 square kilometers.
• Temporal Scale: 20 years (2001–2020).

Methodology and Data

• Models used: Theil-Sen slope analysis, Mann-Kendall test, Rescaled range analysis (R/S) for Hurst index, Optimal Parameter Geographical Detector (OPGD), partial derivative method.
• Data sources:
  • Net Primary Productivity (NPP): MOD17A3HGF (version 6.1) dataset (500-meter spatial resolution, annual).
  • Driving factors (20 variables): Natural environmental factors (climate, soil, vegetation, topography) and human activities (population density, gross domestic product density (GDP)).
  • Climate data: Evapotranspiration, precipitation, sunshine hours, temperature, relative humidity, vapor pressure deficit, soil temperature.
  • Soil data: Soil moisture, soil permeability grade, soil organic matter content, soil clay content, soil sand content, soil silt content, soil type.
  • Topography data: Elevation, slope degree.
  • Vegetation data: Vegetation type, grasslands grazing intensity.
  • Socioeconomic data: Population density and GDP from Inner Mongolia Statistical Yearbook.
  • Land cover data (Yang and Huang, 2024).
  • Google Earth Engine (GEE) platform, ArcGIS Pro (version 3.0.1), MATLAB (version R2024a/b), and R (version 4.4.3) with the "GD" package (version 10.8) for data processing and analysis.

Main Results

• Net Primary Productivity (NPP) in the NFYM region increased by an average of 2.08 grams of carbon per square meter per year (gC⋅m⁻²⋅a⁻¹) from 2001 to 2020, with higher rates in the semi-arid zone (2.36 gC⋅m⁻²⋅a⁻¹) compared to the arid zone (1.82 gC⋅m⁻²⋅a⁻¹).
• Spatially, NPP was consistently higher in the southern and southeastern semi-arid zone and lower in the arid northwestern part. Approximately 65% of the region exhibited significant NPP increases, while declines were rare and spatially clustered in areas of high human impact.
• The mean Hurst index of 0.44 indicates an overall anti-persistent trend, suggesting that past NPP gains are unlikely to persist, with over 80% of the study area showing anti-persistent increases.
• Moisture-related climatic variables (evapotranspiration, precipitation) and soil conditions (soil organic matter content, soil moisture) were the primary drivers of NPP spatial patterns, with evapotranspiration showing the highest explanatory power (q = 0.9408).
• Interactions between climate and human activity factors (e.g., evapotranspiration and economic development) consistently yielded the strongest explanatory power for NPP variation.
• Human activities contributed more to NPP change (67.84%) than climate factors (32.16%) across the NFYM region, with evapotranspiration and precipitation having positive effects, and sunshine hours having a negative effect.
• Most areas (61.9%) exhibited NPP increases driven by the combined influence of climate and human factors, with human-driven increases (22.44%) being more prevalent than climate-dominated increases (15.22%).

Contributions

• Provides a comprehensive analysis of NPP dynamics and its drivers in the relatively underexplored arid-semi-arid agro-pastoral transition zone of the Northern Foothills of the Yinshan Mountains (NFYM).
• Integrates 20 diverse drivers (climate, soil, vegetation, topography, socioeconomic) with advanced spatial attribution approaches (Optimal Parameter Geodetector and partial derivatives) to disentangle individual and interactive contributions of climate and human activities.
• Offers forward-looking projections of NPP trends using the Hurst index, highlighting the anti-persistent nature of current gains and the fragility of the ecosystem.
• Underscores the dominant role of moisture availability and the significant, often positive, influence of human activities (e.g., ecological restoration policies) on dryland vegetation dynamics.
• Develops a methodological framework valuable for studying coupled natural–human drivers of ecosystem change in arid and semi-arid regions globally, providing a scientific basis for targeted ecological conservation and management.

Funding

• Natural Science Foundation of Inner Mongolia Autonomous Region Project (2024LHMS03024, 2024ZD02, 2025ZD007)
• Inner Mongolia Autonomous Region Technology Transfer Project (2021CG0012)
• Inner Mongolia Autonomous Region Science and Technology Plan Project (2024KYPT0004)
• Inner Mongolia Autonomous Region Water Conservancy Technology Project (NSK-2023-02)
• Basic Research Funds Project of China Water Resources and Hydropower Research Institute (MK110145B00012024)

Citation

@article{Ren2025Two,
  author = {Ren, Xiongfei and Li, Xinying and Xin, Yue and Ma, Zhaoxia and Guo, Jianying and Gao, Tianming and Zhao, Le and Zhao, Le and Zhao, Liqing and Zhao, Liqing and Yao, Zhenyu},
  title = {Two decades of vegetation productivity change shaped by water availability and human activity in northern China’s arid–semi-arid transition},
  journal = {Journal of Hydrology Regional Studies},
  year = {2025},
  doi = {10.1016/j.ejrh.2025.102970},
  url = {https://doi.org/10.1016/j.ejrh.2025.102970}
}