Global water use efficiency saturation due to increased vapor pressure deficit

• 成果类型: Article
• 署名作者: Li, Fei; Xiao, Jingfeng; Chen, Jiquan; Ballantyne, Ashley; Jin, Ke; Li, Bing; Abraha, Michael; John, Ranjeet
• 署名单位: Chinese Academy of Agricultural Sciences; Institute of Grassland Research, CAAS; Michigan State University; University System Of New Hampshire; University of New Hampshire; University of Montana System; University of Montana; Universite Paris Saclay; Centre National de la Recherche Scientifique (CNRS); CEA; University of South Dakota; University of South Dakota
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-13120
• DOI: 10.1126/science.adf5041
• 发表日期: 2023-08-11
• 页码: 672-677
• 关键词: gross primary production; stomatal conductance; carbon-dioxide; co2 fertilization; eddy covariance; nitrogen; LAND; evapotranspiration; MODEL; PRODUCTIVITY

摘要

The ratio of carbon assimilation to water evapotranspiration (ET) of an ecosystem, referred to as ecosystem water use efficiency (WUEeco), is widely expected to increase because of the rising atmospheric carbon dioxide concentration (C-a). However, little is known about the interactive effects of rising C-a and climate change on WUEeco. On the basis of upscaled estimates from machine learning methods and global FLUXNET observations, we show that global WUEeco has not risen since 2001 because of the asymmetric effects of an increased vapor pressure deficit (VPD), which depressed photosynthesis and enhanced ET. An undiminished ET trend indicates that rising temperature and VPD may play a more important role in regulating ET than declining stomatal conductance. Projected increases in VPD are predicted to affect the future coupling of the terrestrial carbon and water cycles.