Water availability regulates abrupt shifts in global terrestrial vegetation productivity by reducing resilience

Abrupt shifts in vegetation productivity induced by environmental change profoundly affect ecosystem functions and services, such as carbon sequestration, biodiversity maintenance, and climate regulation, yet their long-term global patterns and underlying drivers remain insufficiently understood. In this study, abrupt shifts in vegetation productivity were identified using two independent long-term satellite datasets, and early warning signals were assessed through ecosystem resilience. The main drivers of resilience decline were further examined across land cover, climate, and human-activity dimensions. The results showed that negative abrupt shifts were predominantly concentrated in high northern latitudes and equatorial regions, and that both negative and positive abrupt shifts displayed distinct increasing trends after 2002. A sharp decline in ecosystem resilience was also detected during the four years preceding abrupt shifts. Changes in water availability were identified as the primary factor contributing to the reduced resilience of global ecosystems, as evidenced by the driver trajectory, generalized additive models, and convergent cross-mapping methods. This study provides insight into the pervasive occurrence of abrupt shifts in vegetation productivity and the discernible impact of climate change. When projecting vegetation dynamics under future climate change, it is essential to consider the significant uncertainties associated with abrupt shifts.

环境变化引发的植被生产力突变，会深刻影响生态系统功能与服务，如碳固存（carbon sequestration）、生物多样性维持（biodiversity maintenance）与气候调节（climate regulation），但目前学界对其全球长期分布格局及潜在驱动因子仍缺乏充分认知。本研究依托两套独立的长期卫星数据集识别植被生产力突变，并通过生态系统韧性（ecosystem resilience）评估预警信号；进一步从土地覆被、气候及人类活动多个维度，解析了生态系统韧性下降的主要驱动因子。结果显示，负向植被生产力突变主要集中在高北纬地区与赤道区域，且2002年后正负向突变均呈现显著上升趋势；在突变发生前的四年间，生态系统韧性同样出现了显著下降。通过驱动轨迹、广义加性模型（Generalized Additive Models）与收敛交叉映射（Convergent Cross-Mapping）方法的分析结果证实，水分可利用性变化是导致全球生态系统韧性下降的核心因素。本研究揭示了植被生产力突变的普遍发生特征，以及气候变化带来的可观测影响。在未来气候变化情景下预测植被动态时，必须充分考虑突变相关的显著不确定性。