Kong et al. (2025) Vegetation carbon use efficiency response to drought in the Manas River Basin of Xinjiang

Identification

• Journal: Scientific Reports
• Year: 2025
• Date: 2025-12-17
• Authors: Jingjing Kong, Mei Zan, Zhizhong Chen, Shunfa Yang, Zhou Jia, Lili Zhai
• DOI: 10.1038/s41598-025-29708-6

Research Groups

• School of Geographic Science and Tourism, Xinjiang Normal University, Urumqi, China
• Xinjiang Laboratory of Lake Environment and Resources in the Arid Zone, Urumqi, China

Short Summary

This study investigated the spatiotemporal dynamics and drought response of vegetation Carbon Use Efficiency (CUE) in the Manas River Basin from 2001 to 2020, revealing a multi-year mean CUE of 0.50 and a dominant 3-month lag effect in CUE response to drought, with forests showing higher resistance and longer lags than croplands.

Objective

• To systematically analyze the spatiotemporal patterns, stability, and drought response characteristics of vegetation Carbon Use Efficiency (CUE) in the Manas River Basin, Xinjiang, from 2001 to 2020, to understand carbon cycling processes and inform dryland ecosystem management.

Study Configuration

• Spatial Scale: Manas River Basin, Xinjiang, China (43°08′-45°97′N, 84°70′-86°67′E), covering an area of 3.40 × 10^4 square kilometers. Data resolutions included 500 meters for NPP, GPP, and land use, and 0.05 degrees for meteorological data and PET.
• Temporal Scale: 2001-2020 (20 years), analyzed at annual, seasonal, and monthly scales.

Methodology and Data

• Models used:
  • Carbon Use Efficiency (CUE) calculation: Ratio of Net Primary Productivity (NPP) to Gross Primary Productivity (GPP).
  • Theil-Sen median trend analysis and Mann-Kendall (M-K) test for trend detection and significance.
  • Hurst index for predicting future trend persistence.
  • Pearson correlation analysis for time-lagged effects between CUE and SPEI.
  • Standardized Precipitation Evapotranspiration Index (SPEI) for drought assessment (1, 3, 6, 12-month scales).
  • Coefficient of Variation (CV) for CUE stability analysis.
  • Morlet Wavelet Analysis for identifying SPEI cyclicity.
  • Ecosystem resilience index (Rd) for quantifying drought resilience.
• Data sources:
  • MODIS satellite data (MOD17 for NPP and GPP) from earthdata.nasa.gov.
  • Monthly air temperature and precipitation data from gre.geodata.cn.
  • Potential Evapotranspiration (PET) from ladsweb.modaps.eosdis.nasa.gov.
  • Land use data from zenodo.org.
  • Digital Elevation Model (DEM) from resdc.cn.
  • Vector map of the administrative boundary of Xinjiang.

Main Results

• The multi-year mean CUE of the Manas River Basin was 0.50 (±0.12), showing a non-significant declining trend from 2001 to 2020, with minimum values in 2008 (0.464) and 2018 (0.463).
• CUE varied significantly by vegetation type: coniferous forests exhibited the highest values, followed by broad-leaved forests, grasslands, and croplands (lowest).
• Seasonal mean CUE displayed strong spatial heterogeneity, with average values of 0.72 in spring, 0.44 in summer, 0.73 in autumn, and 0.01 in winter.
• Spatially, CUE increased in northern desert grasslands and central plain grasslands, while croplands showed a widespread decline.
• Approximately 57.99% of the basin exhibited low CUE fluctuation, primarily in grassland and woodland areas.
• The average Hurst index for CUE was 0.44, indicating anti-persistence (potential trend reversal) in 34.49% of the area, mainly in plain and desert grasslands.
• Wavelet analysis of SPEI revealed multi-scale wet-dry oscillations across all seasons, with dominant cycles varying seasonally (e.g., spring: 5 and 12 years; summer: 3 and 14 years; autumn: 2 and 6 years; winter: 6 and 10 years).
• CUE responded to drought with a predominant 3-month lag effect, covering 36.90% of the watershed area.
• Forests demonstrated stronger drought resistance and longer response lags (up to 12 months) compared to croplands (1.2 months longer, p=0.03).
• Overall, vegetation CUE in the study area exhibited high resilience to drought disturbances, with 59.89% of the region showing resilience (Rd ≥ 1), and crops demonstrating the highest resilience.

Contributions

• Provides a systematic analysis of CUE spatiotemporal patterns, stability, and drought response mechanisms in an arid inland basin, addressing a knowledge gap for such regions.
• Establishes a mechanistic framework for understanding carbon cycling processes in arid lands under climate stress, offering scientific support for global dryland ecosystem management.
• Reveals differential CUE response patterns between irrigated oases and natural ecosystems, providing analogical references for other Central Asian watersheds (e.g., Syr Darya, Amu Darya) and similar climate zones worldwide.
• Highlights the strong coupling between water availability and carbon cycling, the sharp contrasts between irrigated oases and natural deserts, and the high sensitivity to climate oscillations in arid zone ecosystems.
• Identifies irrigation as a mediator of CUE resilience, suggesting its broader applicability in water-scarce regions.

Funding

• Natural Science Foundation of Xinjiang Uygur Autonomous Region (2023D01A49)
• National Natural Science Foundation of China (42261013)

Citation

@article{Kong2025Vegetation,
  author = {Kong, Jingjing and Zan, Mei and Chen, Zhizhong and Yang, Shunfa and Jia, Zhou and Zhai, Lili},
  title = {Vegetation carbon use efficiency response to drought in the Manas River Basin of Xinjiang},
  journal = {Scientific Reports},
  year = {2025},
  doi = {10.1038/s41598-025-29708-6},
  url = {https://doi.org/10.1038/s41598-025-29708-6}
}