The test of the ecohydrological separation hypothesis in a dry zone of the northeastern Tibetan Plateau

Qiu, Xue; Zhang, Mingjun; Wang, Shengjie; Evaristo, Jaivime; Argiriou, Athanassios A.; Guo, Rong; Chen, Rong; Meng, Hongfei; Che, Cunwei; Qu, Deye

doi:10.1002/eco.2077

Cited by 19 publications

(10 citation statements)

References 21 publications

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“…Plants can access shallow and deep soil water, as well as groundwater with a tendency to prioritize the use of stable and continuous water sources (Zhao & Wang, ), at least in regions where some sources are continuously available. Several studies based on an isotope approach and focusing on the identification of different water sources accessed by plants have been conducted at individual sites in many regions of the world and on different plant species (e.g., to name a few recent studies, Allen, Kirchner, Braun, Siegwolf, & Goldsmith, ; Chi, Zhou, Yang, Li, & Zheng, ; Dubbert, Caldeira, Dubbert, & Werner, ; Evaristo et al, ; Nie et al, ; Oerter, Siebert, Bowling, & Bowen, ; Qiu et al, ). Recent meta‐analyses assessed plant water sources across different biomes and plant species (Barbeta & Peñuelas, ; Evaristo, Jasechko, & McDonnell, ; Evaristo & McDonnell, , ).…”

Section: Introductionmentioning

confidence: 99%

Depth distribution of soil water sourced by plants at the global scale: A new direct inference approach

et al. 2020

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The depth distribution of soil water contributions to plant water uptake is poorly known. Here we evaluate the main water sources used by plants at the global scale and the effect of climate and plant groups on water uptake variability and depth distribution. The global meta‐analysis is based on isotope data (δ2H and δ18O) extracted from 65 peer‐reviewed papers published between 1990 and 2017. We applied a new direct inference method to quantify the overlap between xylem water and soil water sources used by plants. The median overlap between xylem water and soil water at different depths varied between 28% and 100%, but they were generally >50%. The shallow (0‐10 cm) soil water overlap with xylem water was largest in cold regions (100% ± 0%) and lowest at tropical sites (about 28%). Conversely, the median overlap between xylem water and deep soil water was largest in the arid and the tropical zones (>75%) and much smaller in the temperate and cold zones. Our results suggest that the isotopic composition of xylem water reflects mostly the signature of shallow soil water (<30 cm) in the cold and the temperate zones, whereas in the arid and the tropical zones, plants appear to exploit water in deeper soil layers. Our novel, simple statistically‐based direct inference method performed well in determining these differences in water sources, and can be applied more widely to isotope‐based plant water uptake studies.

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Section: Introductionmentioning

confidence: 99%

Depth distribution of soil water sourced by plants at the global scale: A new direct inference approach

et al. 2020

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“…Xu et al, (2019) showed that trees transpire water from first rainfall event that recharged soil water storages during the wet season, and supported transpiration during the dry season. While some synthesis (e.g., J. Evaristo, Jasechko, et al, 2015) and field‐based investigations have found that the use of tightly bound water by trees is widespread across different biomes (G. R. Goldsmith, Muñoz‐Villers, et al, 2012; Hervé‐Fernández et al, 2016), others have not (Geris et al, 2015; Qiu et al, 2019). Nevertheless, the mechanisms governing tree water source apportionment are still unclear (Berry et al, 2017; Penna et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Tree water deficit and dynamic source water partitioning

Nehemy

Benettin

Asadollahi

et al. 2020

Hydrological Processes

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The stable isotopes of hydrogen and oxygen (δ 2 H and δ 18 O, respectively) have been widely used to investigate tree water source partitioning. These tracers have shed new light on patterns of tree water use in time and space. However, there are several limiting factors to this methodology (e.g., the difficult assessment of isotope fractionation in trees, and the labor-intensity associated with the collection of significant sample sizes) and the use of isotopes alone has not been enough to provide a mechanistic understanding of source water partitioning. Here, we combine isotope data in xylem and soil water with measurements of tree's physiological information including tree water deficit (TWD), fine root distribution, and soil matric potential, to investigate the mechanism driving tree water source partitioning. We used a 2 m 3 lysimeter with willow trees (Salix viminalis) planted within, to conduct a high spatial-temporal resolution experiment. TWD provided an integrated response of plant water status to water supply and demand. The combined isotopic and TWD measurement showed that short-term variation (within days) in source water partitioning is determined mainly by plant hydraulic response to changes in soil matric potential. We observed

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“…The development of low-cost and easy-to-use spectroscopic techniques for the collection and isotopic analysis of water samples at a high temporal resolution (e.g., Kerstel et al, 1999;Penna et al, 2010;von Freyberg et al, 2017) stimulated the application of stable isotopes to investigate the water fluxes in the soil-plant-atmosphere continuum (Brooks et al, 2010;McDonnell, 2014). An increasing number of new studies has been conducted to better understand water dynamics, such as water uptake and evapotranspiration partitioning, in the soil-plant-low atmosphere continuum in different climates and in both natural (e.g., Allen et al, 2019;Dubbert et al, 2019;Liu et al, 2019a;Oerter et al, 2019;Qiu et al, 2019) and managed (agricultural and agroforest) (e.g., Liu et al, 2019b;Quade et al, 2019;Zhang et al, 2019;Penna et al, 2020) environments. Compared to the rapid increase of the number of studies using a stable isotope approach, only a small fraction of them focused on the comparison of two or more soil or plant water extraction techniques (Sprenger et al, 2015;Orlowski et al, 2016b;Millar et al, 2018;Fischer et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

A comparative study of plant water extraction methods for isotopic analyses: Scholander-type pressure chamber vs. cryogenic vacuum distillation

Zuecco

Amin

Frentress

et al. 2020

Preprint

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Abstract. Recent tracer-based studies using stable isotopes of hydrogen and oxygen showed that different methods for extracting water from plant tissues can return different isotopic composition due to the presence of organic compounds and the extraction of different plant water pools. One of the most used methods to extract plant water is the cryogenic vacuum distillation (CVD), which tends to extract total plant water. Conversely, the Scholander-type pressure chamber (SPC), which is commonly used by tree physiologists to measure shoot water potential and determine plant water stress, has been rarely applied to extract plant water for isotopic analyses. In this work, we analyzed the variability in the isotopic composition of plant water extracted by SPC and CVD, also considering the potential variability in the isotopic signature of the plant tissues (i.e., leaves, twig without bark, twig with bark, twig close to the trunk of the tree, and wood core) and plant species (i.e., alder, apple, chestnut and beech). The extraction of plant water by SPC is simple, can be carried out in situ, and it does not require specific laboratory work as in case of CVD. However, the main limitation of SPC is the very small water volume that can be extracted from the lignified shoots during conditions of water deficit, compared to CVD. Our results indicated that plant water extracted by SPC and CVD were significantly different. The difference in the isotopic composition obtained by the two extraction methods was smaller in the beech samples compared to alder, apple and chestnut samples. The isotopic signature of alder, apple and chestnut plant water extracted by SPC was more enriched in δ2H and δ18O, respectively, than the samples obtained by CVD. We conclude that plant water extraction by SPC is not an alternative for CVD, as SPC likely extracts only water within the xylem (dead cells), whereas CVD tends to retrieve all water stored in the sampled tissue, from both living and dead cells. However, studies aiming to quantify the relative contribution of the water sources to transpiration should rely more on the isotopic composition of xylem water transpiring during the sampling day (which is theoretically sampled by SPC), than the isotopic composition of total plant water (sampled by CVD), which also contains a fraction of water that could be stored in plant tissues for long time.

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The test of the ecohydrological separation hypothesis in a dry zone of the northeastern Tibetan Plateau

Cited by 19 publications

References 21 publications

Depth distribution of soil water sourced by plants at the global scale: A new direct inference approach

Depth distribution of soil water sourced by plants at the global scale: A new direct inference approach

Tree water deficit and dynamic source water partitioning

A comparative study of plant water extraction methods for isotopic analyses: Scholander-type pressure chamber vs. cryogenic vacuum distillation

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