中国植被生产力对干湿变化的响应

Response of vegetation productivity to wet and dry changes in China

随着全球气温的持续升高,水资源可利用性对植被生长的影响是否发生了变化仍不清楚。本文评估了1982—2018年中国植被生产力对干湿变化响应的长期演变趋势及植被响应的时间尺度阈值,这将对降低陆地生态系统管理成本和双碳目标实现具有重要意义。①在研究期内中国植被生产力的水分胁迫不断增强。②在多时间尺度干湿变化中,61.18%的植被覆盖区存在过干旱化显著抑制了该区域的植被光合作用;28.89%的植被覆盖区存在过水分过剩显著抑制了该区域的植被光合作用。③干旱化显著胁迫植被生产力的最小响应时间缩短,而水分过剩显著约束植被生产力的最大响应时间延长,表明干旱化抑制植被生产力影响越来越容易,水分过剩对植被生产力产生抑制作用越来越困难。因此,1982—2018年中国植被生产力的水分约束正在增加。本文结果揭示了气候持续变暖背景下的水资源可利用性对植被生长影响的变化趋势,为水—碳耦合关系及水碳循环提供科学依据。

As global temperatures continue to rise,the impact of water availability on vegetation productivity remains unclear.This study aims to assess the long-term trends of vegetation productivity response to wet and dry changes and the time-scale thresholds of vegetation response in China from 1982 to 2018,which will be important for reducing the management costs of terrestrial ecosystems and achieving the goals of carbon peaking and carbon neutrality.Results show that:(1)Water stress on vegetation productivity in China has increased throughout the study period.(2)In multiple time scale dry and wet variations,61.18%of the vegetated cover areas had water deficit significantly inhibiting vegetative photosynthesis.In contrast,28.29%of the vegetated cover areas had water surplus significantly inhibiting vegetative photosynthesis.(3)The minimum response time for vegetation productivity significantly stressed by aridification has been shortened,while the maximum response time for vegetation productivity significantly constrained by water surplus has been lengthened.These observations indicate that it became easier for aridification to suppress vegetation productivity effects and more difficult for the water surplus to produce suppressive effects on vegetation productivity.Consequently,the water constraint on vegetation productivity in China has been intensifying over the past 37 years.These findings shed light on the evolving trend of water availability in the face of ongoing climate warming,providing a scientific basis for understanding the coupling relationship between water and carbon,as well as the water-carbon cycle.