Chen Weiwei, Wang Zhipeng, Niu Ben, Zhang Yang, Wang Na, Zhang Ruiqing
Institute of Land Engineering and Technology, Shaanxi Provincial Land Engineering Construction Group Co., Ltd., Xi'an, 710075, China.
Hebei Key Laboratory of Intelligent Water Conservancy, School of Water Conservancy and Hydropower, Hebei University of Engineering, Handan, 056038, China.
Environ Res. 2025 Mar 1;268:120803. doi: 10.1016/j.envres.2025.120803. Epub 2025 Jan 9.
Surface greenness alters regional water storage by regulating hydrological processes, thereby modulating water constraints on ecosystem functions and feeding back sustainability. In semi-arid regions, excessive revegetation may exacerbate regional water resource depletion, intensify water limitations on ecosystems, and threaten long-term sustainability. However, these changes have not been adequately assessed. In this study, we employed the Ecosystem Limitation Index (ELI) to differentiate water and energy limitations on ecosystem function. We analyzed its changes and relationship with water storage across China's semi-arid Loess Plateau, where strict revegetation has been implemented since the 2000s. Our results showed a substantial decline in ELI at the plateau scale, suggesting a significant reduction in water limitation. Whereas, ELI increased notably in the eastern and southwestern forest lands, covering 28.4% of the plateau, in contrast to the northwestern grass and desert lands (26.2%), where ELI decreased significantly. The increase in terrestrial water storage (TWS), especially groundwater storage (GWS) availability, is responsible for the declining water constraints on the ecosystem, albeit TWS and GWS substantially reduced with an annual rate of -0.76 cm and -0.49 cm in water thickness, respectively. Spatial trend analysis and Convergence Cross Mapping (CCM) causal detection revealed that the low surface greening rate before 2000 contributed to the regain in TWS and GWS, while the accelerated greening after 2000 has enhanced the shrinkage of regional TWS and GWS. Our findings suggested that the high greening rate of the Loess Plateau over the past decades was potentially achieved at the expense of regional water storage, underscoring the urgent need for water-saving strategies in future revegetation efforts to ensure ecosystem sustainability.
地表植被覆盖情况通过调节水文过程改变区域水储量，进而调节生态系统功能的水分限制并反馈可持续性。在半干旱地区，过度植被恢复可能会加剧区域水资源枯竭，强化生态系统的水分限制，并威胁长期可持续性。然而，这些变化尚未得到充分评估。在本研究中，我们采用生态系统限制指数（ELI）来区分生态系统功能的水分和能量限制。我们分析了其变化以及与中国半干旱黄土高原水储量的关系，自21世纪以来该地区实施了严格的植被恢复措施。我们的结果表明，在高原尺度上ELI大幅下降，表明水分限制显著减少。然而，在占高原面积28.4%的东部和西南部林地，ELI显著增加，与之形成对比的是占26.2%的西北部草地和荒漠地区，ELI显著下降。陆地水储量（TWS）的增加，尤其是地下水储量（GWS）的可利用性，是生态系统水分限制下降的原因，尽管TWS和GWS分别以每年-0.76厘米和-0.49厘米的水层厚度大幅减少。空间趋势分析和收敛交叉映射（CCM）因果检测表明，2000年前较低的地表绿化率有助于TWS和GWS的恢复，而2000年后加速的绿化增强了区域TWS和GWS的缩减。我们的研究结果表明，过去几十年黄土高原的高绿化率可能是以区域水储量为代价实现的，这凸显了未来植被恢复工作中迫切需要节水策略以确保生态系统可持续性。
