Community Composition and Structure Affect Ecosystem and Canopy Water Use Efficiency Across Three Typical Alpine Ecosystems

Yuzhe Li; Xinyuan Zhang; Quanqin Shao; Jiangwen Fan; Zhi Chen; Jinwei Dong; Zhongmin Hu; Yue Zhan

doi:10.3389/fpls.2021.771424

Community Composition and Structure Affect Ecosystem and Canopy Water Use Efficiency Across Three Typical Alpine Ecosystems

Front Plant Sci. 2022 Jan 20:12:771424. doi: 10.3389/fpls.2021.771424. eCollection 2021.

Authors

Yuzhe Li¹, Xinyuan Zhang^{1

2}, Quanqin Shao¹, Jiangwen Fan¹, Zhi Chen³, Jinwei Dong¹, Zhongmin Hu⁴, Yue Zhan⁵

Affiliations

¹ Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.
² School of Earth Sciences and Resources, China University of Geosciences, Beijing, China.
³ Key Laboratory of Ecosystem Network Observation and Modeling, Synthesis Research Center of Chinese Ecosystem Research Network, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.
⁴ School of Geography, South China Normal University, Guangzhou, China.
⁵ College of Forestry, Nanjing Forestry University, Nanjing, China.

Abstract

Unique ecosystems distributed in alpine areas of the Qinghai-Tibetan Plateau play important roles in climate change mitigation, local food supply, and conservation of species diversity. To understand the water use efficiency (WUE) of this fragile and sensitive region, this study combined observed data from the eddy covariance system and the Shuttleworth-Wallace (S-W) model to measure the continuous mass exchange, including gross primary productivity (GPP), evapotranspiration (ET), and canopy transpiration (T) throughout 2 or 3 years (2016-2018) in three common alpine ecosystems (i.e., alpine steppe, alpine meadow, and alpine swamp). These ecosystems represent a water availability gradient and thus provide the opportunity to quantify environmental and biological controls on WUE at various spatiotemporal scales. We analyzed the ecosystem WUE (WUEe; defined as the ratio of GPP to ET) and canopy WUE (WUEc; defined as the ratio of GPP and canopy T). It was found that the yearly WUEe was 1.40, 1.63, and 2.16 g C kg^-1 H₂O, and the yearly WUEc was 8.93, 2.46, and 5.19 g C kg^-1 H₂O in the three typical ecosystems, respectively. The controlling factors of yearly WUE diverged between WUEe and WUEc. We found that plant functional group proportion (e.g., gramineous and Cyperaceae) highly explained the yearly WUEe variation across sites, and a good correlation was observed between community species diversity and WUEc. These findings suggest that community composition and trait change are critical in regulating WUEe and WUEc across different alpine ecosystems and that the regulation mechanisms may differ fundamentally between WUEe and WUEc.

Keywords: Qinghai–Tibetan Plateau; alpine ecosystem; canopy water use efficiency; community characteristics; ecosystem water use efficiency; evapotranspiration partition.