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

Area of Science:

• Ecology
• Environmental Science
• Climate Science

Background:

• Alpine ecosystems on the Qinghai-Tibetan Plateau are vital for climate mitigation and biodiversity.
• Understanding water use efficiency (WUE) is crucial for managing these sensitive environments.

Purpose of the Study:

• To quantify water use efficiency (WUE) in alpine steppe, meadow, and swamp ecosystems.
• To identify environmental and biological factors controlling WUE across different alpine ecosystems.

Main Methods:

• Combined eddy covariance system data with the Shuttleworth-Wallace (S-W) model.
• Measured continuous mass exchange: gross primary productivity (GPP), evapotranspiration (ET), and canopy transpiration (T) from 2016-2018.
• Analyzed ecosystem WUE (WUEe = GPP/ET) and canopy WUE (WUEc = GPP/T).

Main Results:

• Yearly WUEe ranged from 1.40 to 2.16 g C kg⁻¹ H₂O; yearly WUEc ranged from 2.46 to 8.93 g C kg⁻¹ H₂O across the three ecosystems.
• Plant functional group proportion significantly explained variations in WUEe.
• Community species diversity correlated well with WUEc.

Conclusions:

• Community composition and plant traits critically regulate WUEe and WUEc in alpine ecosystems.
• Mechanisms controlling WUEe and WUEc differ fundamentally, highlighting the need for distinct management strategies.