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

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.

Responses in the Coupling of Carbon and Water Vapor Exchanges of Irrigated and Rainfed Andean Potato (<i>Solanum Tuberosum</i> Subsp. Andigenum) Agroecosystems

“…Water and carbon fluxes are tightly coupled systems (Brunsell and Wilson, 2013;Díaz et al, 2022;Gentine et al, 2019;van Dijke et al, 2020a), which tend to be synchronized since they share common environmental controls, and the stomatal path of water vapor and CO2 exchange during photosynthesis (Gentine et al, 2019;Krich et al, 2022;Leuning, 1995;Lin et al, 2015;Lombardozzi et al, 2012). This essential tradeoff of water (ET) for carbon (GPP) (Díaz et al, 2022;Law et al, 2002), and their coupled relationship, could be quantified through water use efficiency (WUE), which connects water and carbon fluxes together and is a key indicator of ecosystem CO2-water coupling (Ali et al, 2017;Gentine et al, 2019;Hu et al, 2008;Keenan et al, 2013a;Li et al, 2022;Niu et al, 2011;Tang et al, 2015). However, though the WUE concept provides useful information to optimize water and carbon management in crop production (Keenan et al, 2013b;Oo et al, 2023;Xie et al, 2016) the influence of vapor pressure deficit (VPD) on canopy conductance (Monteith, 1986;Wagle et al, 2016) could lead to misinterpretation of carbon uptake and water loss responses to environment (Wagle et al, 2016).…”

Editorial: Patterns, functions, and processes of alpine grassland ecosystems under global change

“…Seven papers in this SI assess the variations of alpine ecosystem functions, and the response and feedback of ecological processes using long-term simulated experiments and large-scale transect surveys. Some of the studies used the entire TP as the study area and evaluated the complex biodiversity-ecosystem function relationships ( Zhang et al., 2022 ; Qi et al., 2022 ), the effects of soil physico-chemical properties on plant species diversity ( Han et al., 2022 ), the mechanism of plant communities on different EMF patterns ( Wang et al., 2021 ), and on the canopy water use efficiency ( Li et al., 2022b ). Other studies investigated the impacts of human activities on ecosystems, especially alpine grasslands and meadows, with regard to overgrazing, rodent destroy, and grassland degradation.…”

Assessing carbon dynamics of irrigated and rainfed potato (>i<Solanum tuberosum>/i< L.) cropping systems in the Andean hillside landscape

“…Water and carbon fluxes are tightly coupled systems Díaz et al, 2022;Gentine et al, 2019;van Dijke et al, 2020a), which tend to be synchronized since they share common environmental controls, and the stomatal path of water vapor and CO2 exchange during photosynthesis (Gentine et al, 2019;Krich et al, 2022;Leuning, 1995;Lin et al, 2015;Lombardozzi et al, 2012b). This essential tradeoff of water (ET) for carbon (GPP) (Díaz et al, 2022b;Law et al, 2002b), and their coupled relationship, could be quantified through water use efficiency (WUE), which connects water and carbon fluxes together and is a key indicator of ecosystem CO2-water coupling (Ali et al, 2017;Gentine et al, 2019;Hu et al, 2008;Keenan et al, 2013a;Li et al, 2022;Niu et al, 2011;Tang et al, 2015). However, though the WUE concept provides useful information to optimize water and carbon management in crop production (Keenan et al, 2013b;Oo et al, 2023;Xie et al, 2016) the influence of vapor pressure deficit (VPD) on canopy conductance (Monteith, 1986;Wagle et al, 2016) could lead to misinterpretation of carbon uptake and water loss responses to environment (Wagle et al, 2016).…”