J Plant Ecol ›› 2022, Vol. 15 ›› Issue (5): 921-932 .DOI: 10.1093/jpe/rtac033

• Research Articles • Previous Articles     Next Articles

Variability in evapotranspiration shifts from meteorological to biological control under wet versus drought conditions in an alpine meadow

Mingjie Xu1, Tingting An1, Zhoutao Zheng2,3,4, Tao Zhang1, *, Yangjian Zhang2,3,4,* and Guirui Yu2,4   

  1. 1 College of Agronomy, Shenyang Agricultural University, Shenyang 110866, China, 2 Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China, 3 Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China, 4 College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China

    *Corresponding author. E-mail: zhangt@syau.edu.cn (T.Z.); zhangyj@igsnrr.ac.cn (Y.Z.)
  • Received:2021-06-18 Revised:2021-07-21 Accepted:2021-12-14 Online:2022-03-05 Published:2022-09-01


The Tibetan Plateau is generally referred to as the Chinese water tower, and evapotranspiration (ET) affects the water budget and stability of alpine meadows on the Tibetan Plateau. However, its variability and controlling mechanisms have not been well documented under the drier conditions induced by global warming. Therefore, this study aimed to clarify whether meteorological or biological factors primarily affected the variability in ET under contrasting water conditions in the alpine meadow ecosystem on the Tibetan Plateau. Based on 6-year (2013–2018) eddy covariance observations and the corresponding meteorological and biological data, linear perturbation analyses were employed to isolate the contributions of meteorological and biological factors to the variability in evapotranspiration (δET). The results showed that δET was mainly driven by meteorological factors in wet peak seasons (July and August), and was dominated by net radiation (Rn) and air temperature (Ta), indicating that the inadequate available energy is the factor limiting ET. However, the dominant factors affecting δET shifted from meteorological to biological in dry peak seasons when the canopy stomatal conductance (gs) and leaf area index were dominant. At this point, the ecosystem was limited by the water conditions. These results provide empirical insights into how meteorological and biological factors regulate variability in ET under contrasting water conditions. These findings can further improve our understanding of water cycle processes and can help effectively manage water resources in alpine meadow ecosystems under future climate change conditions.

Key words: ET, climate effects, biotic effects, eddy covariance, Tibetan Plateau

青藏高原被称为中国水塔,其蒸散(evapotranspiration, ET)影响着青藏高原的水分平衡及高寒草甸生态系统的稳定性。然而,全球变化进程对青藏高原蒸散的变异及其控制机制的影响尚不明晰。因此,本研究旨在明晰不同水分条件下,青藏高原高寒草甸生态系统蒸散变异受气象因子主控亦或是受生物因子主控。基于6年(2013–2018)的碳通量与气象因子和生物因子数据,采用线性扰动分析法量化了各气象因子和生物因子对蒸散变异的贡献。研究结果表明,在湿润年的生长旺季(7–8月),气象因子主控蒸散的变异。能量供应的不足限制了蒸散,因此净辐射和温度主控了蒸散的变异。在干旱年的生长旺季,蒸散变异由气象因子主控转变为生物因子主控,蒸散变异主要受到冠层导度和叶面积指数的控制。此时,生态系统受水分限制。本研究为深入研究不同水分条件下气象和生物因子如何控制蒸散变异提供了经验;有助于深刻理解水循环过程,可为未来气候变化条件下有效管理高寒草甸生态系统水资源提供理论基础。

关键词: 蒸散, 气象影响, 生物影响, 涡度相关, 青藏高原