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Morgner E, Holloway-Phillips M, Basler D, Nelson DB, Kahmen A. Effects of increasing atmospheric CO 2 on leaf water δ 18O values are small and are attenuated in grasses and amplified in dicotyledonous herbs and legumes when transferred to cellulose δ 18O values. THE NEW PHYTOLOGIST 2024. [PMID: 38575849 DOI: 10.1111/nph.19713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 03/08/2024] [Indexed: 04/06/2024]
Abstract
The oxygen isotope composition of cellulose (δ18O values) has been suggested to contain information on stomatal conductance (gs) responses to rising pCO2. The extent by which pCO2 affects leaf water and cellulose δ18O values (δ18OLW and δ18OC) and the isotope processes that determine pCO2 effects on δ18OLW and δ18OC are, however, unknown. We tested the effects of pCO2 on gs, δ18OLW and δ18OC in a glasshouse experiment, where six plant species were grown under pCO2 ranging from 200 to 500 ppm. Increasing pCO2 caused a decline in gs and an increase in δ18OLW, as expected. Importantly, the effects of pCO2 on gs and δ18OLW were small and pCO2 effects on δ18OLW were not directly transferred to δ18OC but were attenuated in grasses and amplified in dicotyledonous herbs and legumes. This is likely because of functional group-specific pCO2 effects on the model parameter pxpex. Our study highlights important uncertainties when using δ18OC as a proxy for gs. Specifically, pCO2-triggered gs effects on δ18OLW and δ18OC are possibly too small to be detected in natural settings and a pCO2 effect on pxpex may render the commonly assumed negative linkage between δ18OC and gs to be incorrect, potentially confounding δ18OC based gs reconstructions.
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Affiliation(s)
- Eva Morgner
- Department of Environmental Sciences - Botany, University of Basel, 4056, Basel, Switzerland
| | | | - David Basler
- Department of Environmental Sciences - Botany, University of Basel, 4056, Basel, Switzerland
| | - Daniel B Nelson
- Department of Environmental Sciences - Botany, University of Basel, 4056, Basel, Switzerland
| | - Ansgar Kahmen
- Department of Environmental Sciences - Botany, University of Basel, 4056, Basel, Switzerland
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Holloway-Phillips M, Baan J, Nelson DB, Lehmann MM, Tcherkez G, Kahmen A. Species variation in the hydrogen isotope composition of leaf cellulose is mostly driven by isotopic variation in leaf sucrose. PLANT, CELL & ENVIRONMENT 2022; 45:2636-2651. [PMID: 35609972 DOI: 10.1111/pce.14362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 05/11/2022] [Indexed: 06/15/2023]
Abstract
Experimental approaches to isolate drivers of variation in the carbon-bound hydrogen isotope composition (δ2 H) of plant cellulose are rare and current models are limited in their application. This is in part due to a lack in understanding of how 2 H-fractionations in carbohydrates differ between species. We analysed, for the first time, the δ2 H of leaf sucrose along with the δ2 H and δ18 O of leaf cellulose and leaf and xylem water across seven herbaceous species and a starchless mutant of tobacco. The δ2 H of sucrose explained 66% of the δ2 H variation in cellulose (R2 = 0.66), which was associated with species differences in the 2 H enrichment of sucrose above leaf water ( ε sucrose <math altimg="urn:x-wiley:01407791:media:pce14362:pce14362-math-0001" wiley:location="equation/pce14362-math-0001.png" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mtext>\unicode{x003B5}</mtext><mtext>sucrose</mtext></msub></mrow></math> : -126% to -192‰) rather than by variation in leaf water δ2 H itself. ε sucrose <math altimg="urn:x-wiley:01407791:media:pce14362:pce14362-math-0002" wiley:location="equation/pce14362-math-0002.png" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mtext>\unicode{x003B5}</mtext><mtext>sucrose</mtext></msub></mrow></math> was positively related to dark respiration (R2 = 0.27), and isotopic exchange of hydrogen in sugars was positively related to the turnover time of carbohydrates (R2 = 0.38), but only when ε sucrose <math altimg="urn:x-wiley:01407791:media:pce14362:pce14362-math-0003" wiley:location="equation/pce14362-math-0003.png" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mrow><msub><mi mathvariant="normal">\unicode{x003B5}</mi><mtext>sucrose</mtext></msub></mrow></mrow></math> was fixed to the literature accepted value of - 171 <math altimg="urn:x-wiley:01407791:media:pce14362:pce14362-math-0004" wiley:location="equation/pce14362-math-0004.png" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mrow><mo>\unicode{x02212}</mo><mn>171</mn></mrow></mrow></math> ‰. No relation was found between isotopic exchange of hydrogen and oxygen, suggesting large differences in the processes shaping post-photosynthetic fractionation between elements. Our results strongly advocate that for robust applications of the leaf cellulose hydrogen isotope model, parameterization utilizing δ2 H of sugars is needed.
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Affiliation(s)
| | - Jochem Baan
- Department of Environmental Science-Botany, University of Basel, Basel, Switzerland
| | - Daniel B Nelson
- Department of Environmental Science-Botany, University of Basel, Basel, Switzerland
| | - Marco M Lehmann
- Research Unit of Forest Dynamics, Research Group of Ecosystem Ecology, Stable Isotope Research Centre, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmendsorf, Switzerland
| | - Guillaume Tcherkez
- Research School of Biology, College of Science, Australian National University, Canberra, Australian Capital Territory, Australia
- Institut de Recherche en Horticulture et Semences, Université d'Angers, INRAe, Beaucouzé, France
| | - Ansgar Kahmen
- Department of Environmental Science-Botany, University of Basel, Basel, Switzerland
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Cueni F, Nelson DB, Lehmann MM, Boner M, Kahmen A. Constraining parameter uncertainty for predicting oxygen and hydrogen isotope values in fruit. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:5016-5032. [PMID: 35512408 DOI: 10.1093/jxb/erac180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 05/04/2022] [Indexed: 06/14/2023]
Abstract
Understanding δ18O and δ2H values of agricultural products like fruit is of particular scientific interest in plant physiology, ecology, and forensic studies. Applications of mechanistic stable isotope models to predict δ18O and δ2H values of water and organic compounds in fruit, however, are hindered by a lack of empirical parameterizations and validations. We addressed this lack of data by experimentally evaluating model parameter values required to model δ18O and δ2H values of water and organic compounds in berries and leaves from strawberry and raspberry plants grown at different relative humidities. Our study revealed substantial differences between leaf and berry isotope values, consistent across the different relative humidity treatments. We demonstrated that existing isotope models can reproduce water and organic δ18O and δ2H values for leaves and berries. Yet, these simulations require organ-specific model parameterization to accurately predict δ18O and δ2H values of leaf and berry tissue and water pools. We quantified these organ-specific model parameters for both species and relative humidity conditions. Depending on the required model accuracy, species- and environment-specific model parameters may be justified. The parameter values determined in this study thus facilitate applications of stable isotope models where understanding δ18O and δ2H values of fruit is of scientific interest.
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Affiliation(s)
- Florian Cueni
- University of Basel, Department of Environmental Sciences - Botany, Schönbeinstrasse 6, 4056 Basel, Switzerland
- Agroisolab GmbH, Professor-Rehm-Strasse 6, 52428 Jülich, Germany
| | - Daniel B Nelson
- University of Basel, Department of Environmental Sciences - Botany, Schönbeinstrasse 6, 4056 Basel, Switzerland
| | - Marco M Lehmann
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Markus Boner
- Agroisolab GmbH, Professor-Rehm-Strasse 6, 52428 Jülich, Germany
| | - Ansgar Kahmen
- University of Basel, Department of Environmental Sciences - Botany, Schönbeinstrasse 6, 4056 Basel, Switzerland
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Wang Y, Yu W, Luo L, Li M, Liu X, Guo R, Ma Y, Xu B, Wu G, Zhao C, Jing Z, Wei F, Cui J, Zhang J, Qu D. How do precipitation events modify the stable isotope ratios in leaf water at Lhasa on the southern Tibetan Plateau? ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2022; 58:229-246. [PMID: 35503680 DOI: 10.1080/10256016.2022.2062343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 03/15/2022] [Indexed: 06/14/2023]
Abstract
Serving as a medium between source water and cellulose, leaf water contributes to the isotope ratios (δ18O, δ2H) of plant organic matter, which can be used for paleoclimate reconstruction. This study is the first to examine the diurnal variations in the δ18O and δ2H of leaf water on the southern Tibetan Plateau. The δ18O and δ2H of leaf water were relatively low when precipitation events occurred. In particular, 18O and 2H of leaf water became extremely depleted 5 h after the precipitation event. Our findings demonstrate that precipitation can modify the isotope ratios of leaf water from external and internal causes. First, precipitation events affect meteorological elements, lead to decreases in leaf transpiration, and immediately weaken the isotope enrichment of leaf water ('rapid effect' of precipitation). Second, precipitation events affect the internal plant-soil water cycle process, causing the plant to preferentially use deeper soil water, and the corresponding isotope ratios of leaf water exhibit extremely low values 5 h after precipitation events ('delay effect' of precipitation). This study suggests that researchers need to be cautious in separating the signals of precipitation and hydrological processes when interpreting isotope records preserved in tree-ring cellulose archives from the Tibetan Plateau.
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Affiliation(s)
- Yong Wang
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Wusheng Yu
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
- CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, People's Republic of China
| | - Lun Luo
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Minghui Li
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Xiaoming Liu
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Rong Guo
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Yaoming Ma
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
- CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Baiqing Xu
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
- CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, People's Republic of China
| | - Guangjan Wu
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
- CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, People's Republic of China
| | - Chengyi Zhao
- Land Science Research Center, School of Geographical Sciences, Nanjing University of Information Science & Technology, Nanjing, People's Republic of China
| | - Zhaowei Jing
- Deep-Sea Multidisciplinary Research Center, Pilot National Laboratory of Marine Science and Technology (Qingdao), Qingdao, China
| | - Feili Wei
- College of Urban and Environmental Sciences, Peking University, Beijing, People's Republic of China
| | - Jiangpeng Cui
- College of Urban and Environmental Sciences, Peking University, Beijing, People's Republic of China
| | - Jingyi Zhang
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Dongmei Qu
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, People's Republic of China
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Cueni F, Nelson DB, Kahmen A. Effects of phenotypic variability on the oxygen and hydrogen isotope compositions of grains in different winter wheat varieties. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2022; 58:60-80. [PMID: 34846959 DOI: 10.1080/10256016.2021.2002855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 09/25/2021] [Indexed: 06/13/2023]
Abstract
Stable isotope analyses are the leading method for geographic origin determination, especially of plant-based agricultural products. Origin analysis is typically done by comparing a suspicious sample to reference materials with known geographic origin. Reference materials are usually collected at the species level, assuming different varieties of a species to have comparable isotope compositions within a given location. We evaluated whether different phenotypes that are expressed in different varieties of winter wheat (Triticum aestivum L.) influence the oxygen (δ18O) and hydrogen (δ2H) isotope composition of plant tissue water and organic compounds. We found that mean δ18O and δ2H values among winter wheat varieties did not differ significantly in leaf water, however, differed significantly in bulk dried grain tissue. The differences in bulk dried grain δ18O and δ2H values among varieties can be related to differences in phenotypic trait expression among varieties. Despite this substantial phenotypic variability, the overall variability of bulk dried grain δ18O and δ2H values among varieties was small (SD 0.54 ‰ for oxygen, 3.60 ‰ for hydrogen). We thus conclude that reference materials collected at the species level should be sufficient for geographic origin analysis of winter wheat and possibly other cereals using δ18O and δ2H values.
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Affiliation(s)
- Florian Cueni
- Department of Environmental Sciences - Botany, University of Basel, Basel, Switzerland
- Agroisolab GmbH, Jülich, Germany
| | - Daniel B Nelson
- Department of Environmental Sciences - Botany, University of Basel, Basel, Switzerland
| | - Ansgar Kahmen
- Department of Environmental Sciences - Botany, University of Basel, Basel, Switzerland
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Wang P, Sun H, Li XY, Song X, Yang X, Wu X, Hu X, Yao H, Ma J, Ma J. Seasonal variations in water flux compositions controlled by leaf development: isotopic insights at the canopy-atmosphere interface. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2021; 65:1719-1732. [PMID: 33851245 DOI: 10.1007/s00484-021-02126-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 03/31/2021] [Accepted: 04/02/2021] [Indexed: 06/12/2023]
Abstract
Water-stable isotopes provide a valuable tool for tracing plant-water interactions, particularly evapotranspiration (ET) partitioning and leaf water dynamics at the plant-atmosphere interface. However, process-based investigations of plant/leaf development and the associated isotopic dynamics of water fluxes involving isotope enrichment at plant-atmosphere interfaces at the ecosystem scale remain challenging. In this study, in situ isotopic measurements and tracer-aided models were used to study the dynamic interactions between vegetation growth and the isotopic dynamics of water fluxes (ET, soil evaporation, and transpiration) involving isotope enrichment in canopy leaves in a multispecies grassland ecosystem. The day-to-day variations in the isotopic compositions of ET flux were mainly controlled by plant growth, which could be explained by the significant logarithmic relationship determined between the leaf area index and transpiration fraction. Leaf development promoted a significant increase in the isotopic composition of ET and led to a slight decrease in the isotopic composition of water in canopy leaves. The transpiration (evaporation) isoflux acted to increase (decrease) the δ18O of water vapor, and the total isoflux impacts depended on the seasonal tradeoffs between transpiration and evaporation. The isotopic evidence in ET fluxes demonstrates the biotic controls on day-to-day variations in water/energy flux partitioning through transpiration activity. This study emphasizes that stable isotopes of hydrogen and oxygen are effective tools for quantitative evaluations of the hydrological component partitioning of ecosystems and plant-climate interactions.
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Affiliation(s)
- Pei Wang
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China.
| | - Haitao Sun
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
| | - Xiao-Yan Li
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
| | - Xin Song
- College of Life Sciences and Oceanography, Shenzhen University, 3688 Nanshan Avenue, Shenzhen, 518000, Guangdong, China
| | - Xiaofan Yang
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
| | - Xiuchen Wu
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
| | - Xia Hu
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
| | - Hongyun Yao
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
| | - Jingjing Ma
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
| | - Juanjuan Ma
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
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Cueni F, Nelson DB, Boner M, Kahmen A. Using plant physiological stable oxygen isotope models to counter food fraud. Sci Rep 2021; 11:17314. [PMID: 34453087 PMCID: PMC8397719 DOI: 10.1038/s41598-021-96722-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 08/11/2021] [Indexed: 02/07/2023] Open
Abstract
Fraudulent food products, especially regarding false claims of geographic origin, impose economic damages of $30-$40 billion per year. Stable isotope methods, using oxygen isotopes (δ18O) in particular, are the leading forensic tools for identifying these crimes. Plant physiological stable oxygen isotope models simulate how precipitation δ18O values and climatic variables shape the δ18O values of water and organic compounds in plants. These models have the potential to simplify, speed up, and improve conventional stable isotope applications and produce temporally resolved, accurate, and precise region-of-origin assignments for agricultural food products. However, the validation of these models and thus the best choice of model parameters and input variables have limited the application of the models for the origin identification of food. In our study we test model predictions against a unique 11-year European strawberry δ18O reference dataset to evaluate how choices of input variable sources and model parameterization impact the prediction skill of the model. Our results show that modifying leaf-based model parameters specifically for fruit and with product-independent, but growth time specific environmental input data, plant physiological isotope models offer a new and dynamic method that can accurately predict the geographic origin of a plant product and can advance the field of stable isotope analysis to counter food fraud.
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Affiliation(s)
- Florian Cueni
- Department of Environmental Sciences - Botany, University of Basel, Schönbeinstrasse 6, 4056, Basel, Switzerland.
- Agroisolab GmbH, Professor-Rehm-Strasse 6, 52428, Jülich, Germany.
| | - Daniel B Nelson
- Department of Environmental Sciences - Botany, University of Basel, Schönbeinstrasse 6, 4056, Basel, Switzerland
| | - Markus Boner
- Agroisolab GmbH, Professor-Rehm-Strasse 6, 52428, Jülich, Germany
| | - Ansgar Kahmen
- Department of Environmental Sciences - Botany, University of Basel, Schönbeinstrasse 6, 4056, Basel, Switzerland
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Timofeeva G, Treydte K, Bugmann H, Salmon Y, Rigling A, Schaub M, Vollenweider P, Siegwolf R, Saurer M. How does varying water supply affect oxygen isotope variations in needles and tree rings of Scots pine? TREE PHYSIOLOGY 2020; 40:1366-1380. [PMID: 32589748 DOI: 10.1093/treephys/tpaa082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 04/01/2020] [Accepted: 06/19/2020] [Indexed: 06/11/2023]
Abstract
In many regions, drought is suspected to be a cause of Scots pine decline and mortality, but the underlying physiological mechanisms remain unclear. Because of their relationship to ecohydrological processes, δ18O values in tree rings are potentially useful for deciphering long-term physiological responses and tree adaptation to increasing drought. We therefore analyzed both needle- and stem-level isotope fractionations in mature trees exposed to varying water supply. In a first experiment, we investigated seasonal δ18O variations in soil and needle water of Scots pine in a dry inner Alpine valley in Switzerland, comparing drought-stressed trees with trees that were irrigated for more than 10 years. In a second experiment, we analyzed twentieth-century δ18O variations in tree rings of the same forest, including a group of trees that had recently died. We observed less 18O enrichment in needle water of drought-stressed compared with irrigated trees. We applied different isotope fractionation models to explain these results, including the Péclet and the two-pool correction, which considers the ratio of unenriched xylem water in the needles to total needle water. Based on anatomical measurements, we found this ratio to be unchanged in drought-stressed needles, although they were shorter. The observed lower 18O enrichment in needles of stressed trees was therefore likely caused by increased effective path length for water movement within the leaf lamina. In the tree-ring study, we observed lower δ18O values in tree rings of dead trees compared with survivors during several decades prior to their death. These lower values in declining trees are consistent with the lower needle water 18O enrichment observed for drought-stressed compared with irrigated trees, suggesting that this needle-level signal is reflected in the tree rings, although changes in rooting depth could also play a role. Our study demonstrates that long-term effects of drought are reflected in the tree-ring δ18O values, which helps to provide a better understanding of past tree physiological changes of Scots pine.
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Affiliation(s)
- Galina Timofeeva
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), Villigen 5232, Switzerland
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
- Forest Ecology, Institute of Terrestrial Ecosystems, ETH Zurich, Zurich 8092, Switzerland
| | - Kerstin Treydte
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
| | - Harald Bugmann
- Forest Ecology, Institute of Terrestrial Ecosystems, ETH Zurich, Zurich 8092, Switzerland
| | - Yann Salmon
- Department of Physics, University of Helsinki, Helsinki 00014, Finland
- School of GeoSciences, University of Edinburgh, Edinburgh EH9 3FF, UK
| | - Andreas Rigling
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
| | - Marcus Schaub
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
| | - Pierre Vollenweider
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
| | - Rolf Siegwolf
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), Villigen 5232, Switzerland
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
| | - Matthias Saurer
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), Villigen 5232, Switzerland
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
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A Plant's Electrical Parameters Indicate Its Physiological State: A Study of Intracellular Water Metabolism. PLANTS 2020; 9:plants9101256. [PMID: 32977716 PMCID: PMC7598578 DOI: 10.3390/plants9101256] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 02/03/2023]
Abstract
Almost all of a plant’s life activities involve electrochemical reactions. Plant electrical parameters respond quickly to environmental changes and are closely related to physiological activities. In this study, the theoretical intrinsic relationships between clamping force and leaf impedance (Z) or capacitive reactance (Xc) and capacitance (C) were revealed as 3-parameter exponential decay and linear models based on bioenergetics, respectively, for the first time. Leaf electrical characteristics including intrinsic impedance (IZ), capacitive reactance (IXc), capacitance (IC) and specific effective thickness (d) were successfully detected using the above-mentioned relationships and were used to manifest plant metabolic activity. The intracellular water-holding capacity (IWHC), water-use efficiency (IWUE), water-holding time (IWHT) and water transfer rate (WTR) of plant leaves were defined on the basis of IZ, IXc, IC and d, and applied to reflect the intracellular water metabolism. The results demonstrated that the leaves of Broussonetia papyrifera plants grown in agricultural soil had higher IC, d, IWHC, WTR, water content values and lower IZ, IXc values than those grown in moderately rocky desertified soil. The leaf IC, d, IWHC, WTR and water content values of herbaceous plants were higher than those of woody plants. Solanum tuberosum L. had higher leaf IC, d, IWHC and WTR values, but exhibited lower IZ, IXc, IWUE and IWHT values than Capsicum annuum L. This study highlighted that a plant’s electrical parameters based on bioenergetics clearly indicate its physiological process—e.g., the intracellular water metabolism.
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Ulrich DEM, Still C, Brooks JR, Kim Y, Meinzer FC. Investigating old-growth ponderosa pine physiology using tree-rings, δ 13 C, δ 18 O, and a process-based model. Ecology 2019; 100:e02656. [PMID: 30756385 PMCID: PMC6645703 DOI: 10.1002/ecy.2656] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/19/2018] [Accepted: 01/16/2019] [Indexed: 11/07/2022]
Abstract
In dealing with predicted changes in environmental conditions outside those experienced today, forest managers and researchers rely on process-based models to inform physiological processes and predict future forest growth responses. The carbon and oxygen isotope ratios of tree-ring cellulose (δ13 Ccell , δ18 Ocell ) reveal long-term, integrated physiological responses to environmental conditions. We incorporated a submodel of δ18 Ocell into the widely used Physiological Principles in Predicting Growth (3-PG) model for the first time, to complement a recently added δ13 Ccell submodel. We parameterized the model using previously reported stand characteristics and long-term trajectories of tree-ring growth, δ13 Ccell , and δ18 Ocell collected from the Metolius AmeriFlux site in central Oregon (upland trees). We then applied the parameterized model to a nearby set of riparian trees to investigate the physiological drivers of differences in observed basal area increment (BAI) and δ13 Ccell trajectories between upland and riparian trees. The model showed that greater available soil water and maximum canopy conductance likely explain the greater observed BAI and lower δ13 Ccell of riparian trees. Unexpectedly, both observed and simulated δ18 Ocell trajectories did not differ between the upland and riparian trees, likely due to similar δ18 O of source water isotope composition. The δ18 Ocell submodel with a Peclet effect improved model estimates of δ18 Ocell because its calculation utilizes 3-PG growth and allocation processes. Because simulated stand-level transpiration (E) is used in the δ18 O submodel, aspects of leaf-level anatomy such as the effective path length for transport of water from the xylem to the sites of evaporation could be estimated.
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Affiliation(s)
- Danielle E. M. Ulrich
- Bioscience DivisionLos Alamos National LaboratoryP.O. Box 1663 MS M888Los AlamosNew Mexico87545USA
| | - Christopher Still
- Department of Forest Ecosystems and SocietyOregon State UniversityCorvallisOregon97331USA
| | - J. Renée Brooks
- Western Ecology DivisionUS EPA/NHEERLCorvallisOregon97331USA
| | - Youngil Kim
- Department of Forest Ecosystems and SocietyOregon State UniversityCorvallisOregon97331USA
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11
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Barçante Ladvocat Cintra B, Gloor M, Boom A, Schöngart J, Locosselli GM, Brienen R. Contrasting controls on tree ring isotope variation for Amazon floodplain and terra firme trees. TREE PHYSIOLOGY 2019; 39:845-860. [PMID: 30824929 PMCID: PMC6594573 DOI: 10.1093/treephys/tpz009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 12/10/2018] [Accepted: 01/15/2019] [Indexed: 05/04/2023]
Abstract
Isotopes in tropical trees rings can improve our understanding of tree responses to climate. We assessed how climate and growing conditions affect tree-ring oxygen and carbon isotopes (δ18OTR and δ13CTR) in four Amazon trees. We analysed within-ring isotope variation for two terra firme (non-flooded) and two floodplain trees growing at sites with varying seasonality. We find distinct intra-annual patterns of δ18OTR and δ13CTR driven mostly by seasonal variation in weather and source water δ18O. Seasonal variation in isotopes was lowest for the tree growing under the wettest conditions. Tree ring cellulose isotope models based on existing theory reproduced well observed within-ring variation with possible contributions of both stomatal and mesophyll conductance to variation in δ13CTR. Climate analysis reveal that terra firme δ18OTR signals were related to basin-wide precipitation, indicating a source water δ18O influence, while floodplain trees recorded leaf enrichment effects related to local climate. Thus, intrinsically different processes (source water vs leaf enrichment) affect δ18OTR in the two different species analysed. These differences are likely a result of both species-specific traits and of the contrasting growing conditions in the floodplains and terra firme environments. Simultaneous analysis of δ13CTR and δ18OTR supports this interpretation as it shows strongly similar intra-annual patterns for both isotopes in the floodplain trees arising from a common control by leaf stomatal conductance, while terra firme trees showed less covariation between the two isotopes. Our results are interesting from a plant physiological perspective and have implications for climate reconstructions as trees record intrinsically different processes.
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Affiliation(s)
| | - Manuel Gloor
- School of Geography, University of Leeds, Leeds, Garstang North
| | - Arnoud Boom
- School of Geology, Geography and the Environment, Bennett Building, University Road, University of Leicester, Leicester, UK
| | - Jochen Schöngart
- National Institute for Amazon Research, Av. André Araújo, 2.936, Petrópolis, CEP 69.067-375, Manaus, Amazonas Brazil
| | - Giuliano Maselli Locosselli
- Institute of Biosciences, University of São Paulo, Rua do Matão, 14, Butantã, São Paulo, CEP 05508-090, Brazil
| | - Roel Brienen
- School of Geography, University of Leeds, Leeds, Garstang North
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12
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Belmecheri S, Wright WE, Szejner P, Morino KA, Monson RK. Carbon and oxygen isotope fractionations in tree rings reveal interactions between cambial phenology and seasonal climate. PLANT, CELL & ENVIRONMENT 2018; 41:2758-2772. [PMID: 29995977 DOI: 10.1111/pce.13401] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 06/23/2018] [Accepted: 07/02/2018] [Indexed: 06/08/2023]
Abstract
We developed novel approaches for using the isotope composition of tree-ring subdivisions to study seasonal dynamics in tree-climate relations. Across a 30-year time series, the δ13 C and δ18 O values of the earlywood (EW) cellulose in the annual rings of Pinus ponderosa reflected relatively high intrinsic water-use efficiencies and high evaporative fractionation of 18 O/16 O, respectively, compared with the false latewood (FLW), summerwood (SW), and latewood (LW) subdivisions. This result is counterintuitive, given the spring origins of the EW source water and midsummer origins of the FLW, SW, and LW. With the use of the Craig-Gordon (CG), isotope-climate model revealed that the isotope ratios in all of the ring subdivision are explained by the existence of seasonal lags, lasting several weeks, between the initial formation of tracheids and the production of cellulosic secondary cell walls during maturation. In contrast to some past studies, modification of the CG model according to conventional methods to account for mixing of needle water between fractionated and nonfractionated sources did not improve the accuracy of predictions. Our results reveal new potential in the use of tree-ring isotopes to reconstruct past intra-annual tree-climate relations if lags in cambial phenology are reconciled with isotope ratio observations and included in theoretical treatments.
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Affiliation(s)
- Soumaya Belmecheri
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona
| | - William E Wright
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona
| | - Paul Szejner
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona
| | - Kiyomi A Morino
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona
| | - Russell K Monson
- Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona
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13
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Liang J, Wright JS, Cui X, Sternberg L, Gan W, Lin G. Leaf anatomical traits determine the 18 O enrichment of leaf water in coastal halophytes. PLANT, CELL & ENVIRONMENT 2018; 41:2744-2757. [PMID: 29996176 DOI: 10.1111/pce.13398] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 07/02/2018] [Indexed: 06/08/2023]
Abstract
Anatomical adaptations to high-salinity environments in mangrove leaves may be recorded in leaf water isotopes. Recent studies observed lower 18 O enrichment (ΔL ) of leaf water with respect to source water in three mangrove species relative to adjacent freshwater trees, but the factors that govern this phenomenon remain unclear. To resolve this issue, we investigated leaf traits and ΔL in 15 species of true mangrove plants, 14 species of adjacent freshwater trees, and 4 species of semi-mangrove plants at five study sites along south-eastern coast of China. Our results confirm that ΔL was generally 3-4‰ lower for mangrove species than for adjacent freshwater or semi-mangrove species. We hypothesized that higher leaf water content (LWC) and lower leaf stomatal density (LS) both played important roles in reducing ΔL in mangroves relative to nearby freshwater plants. Both differences acted to elongate effective leaf mixing length (L) in mangroves by about 200% and lower stomatal conductance by about 30%. Péclet models based on both LWC and LS could accurately predict ΔL . Our findings highlight the potential species-specific anatomical determinants of ΔL (or L), which has important implications for the interpretation of environmental information from metabolites produced by leaf water isotopes in palaeoclimate research.
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Affiliation(s)
- Jie Liang
- Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing, China
- Joint Center for Global Change Studies, Beijing, China
- Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen, China
| | - Jonathan S Wright
- Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing, China
- Joint Center for Global Change Studies, Beijing, China
| | - Xiaowei Cui
- Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing, China
- Joint Center for Global Change Studies, Beijing, China
- Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen, China
| | - Leonel Sternberg
- Department of Biology, University of Miami, Coral Gables, Florida
| | - Weixiu Gan
- Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing, China
- Joint Center for Global Change Studies, Beijing, China
- Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen, China
| | - Guanghui Lin
- Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing, China
- Joint Center for Global Change Studies, Beijing, China
- Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen, China
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14
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Brinkmann N, Seeger S, Weiler M, Buchmann N, Eugster W, Kahmen A. Employing stable isotopes to determine the residence times of soil water and the temporal origin of water taken up by Fagus sylvatica and Picea abies in a temperate forest. THE NEW PHYTOLOGIST 2018; 219:1300-1313. [PMID: 29888480 DOI: 10.1111/nph.15255] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 05/03/2018] [Indexed: 06/08/2023]
Abstract
We assessed how the seasonal variability of precipitation δ2 H and δ18 O is propagated into soil and xylem waters of temperate trees, applied a hydrological model to estimate the residence time distribution of precipitation in the soil, and identified the temporal origin of water taken up by Picea abies and Fagus sylvatica over 4 yr. Residence times of precipitation in the soil varied between a few days and several months and increased with soil depth. On average, 50% of water consumed by trees throughout a year had precipitated during the growing season, while 40% had precipitated in the preceding winter or even earlier. Importantly, we detected subtle differences with respect to the temporal origin of water used by the two species. We conclude that both current precipitation and winter precipitation are important for the water supply of temperate trees and that winter precipitation could buffer negative impacts of spring or summer droughts. Our study additionally provides the means to obtain realistic estimates of source water δ2 H and δ18 O values for trees from precipitation isotope data, which is essential for improving model-based interpretations of δ18 O and δ2 H values in plants.
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Affiliation(s)
- Nadine Brinkmann
- Institute of Agricultural Sciences, ETH Zürich, Universitätsstrasse 2, Zurich, 8092, Switzerland
- Department of Environmental Sciences - Botany, University Basel, Schönbeinstrasse 6, Basel, 4056, Switzerland
| | - Stefan Seeger
- Faculty of Environment and Natural Resources, University of Freiburg, Fahnenbergplatz 1, Freiburg, 79098, Germany
| | - Markus Weiler
- Faculty of Environment and Natural Resources, University of Freiburg, Fahnenbergplatz 1, Freiburg, 79098, Germany
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH Zürich, Universitätsstrasse 2, Zurich, 8092, Switzerland
| | - Werner Eugster
- Institute of Agricultural Sciences, ETH Zürich, Universitätsstrasse 2, Zurich, 8092, Switzerland
| | - Ansgar Kahmen
- Department of Environmental Sciences - Botany, University Basel, Schönbeinstrasse 6, Basel, 4056, Switzerland
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15
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Plavcová L, Hronková M, Šimková M, Květoň J, Vráblová M, Kubásek J, Šantrůček J. Seasonal variation of δ 18O and δ 2H in leaf water of Fagus sylvatica L. and related water compartments. JOURNAL OF PLANT PHYSIOLOGY 2018; 227:56-65. [PMID: 29606360 DOI: 10.1016/j.jplph.2018.03.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 03/15/2018] [Indexed: 05/25/2023]
Abstract
The study aims to assess variability in leaf water isotopic enrichment occurring in the field under natural conditions. We focused on seasonal variation and difference between sun-exposed and shaded leaves. Isotopic composition (δ18O, δ2H) of leaf water was monitored in a beech tree (Fagus sylvatica L.) growing in the forest-meadow ecotone together with δ18O (2H) of water compartments which are in close relation to this signal, namely twig and soil water. The sampling was carried out in approximately two-week intervals during five consecutive vegetation seasons. The δ18O (2H) data showed a distinct seasonal pattern and a consistency in relative differences between the seasons and sample categories. Leaf water was the most isotopically enriched water compartment. The leaf water enrichment decreased toward the autumn reflecting the change in δ18O (2H) of source water and evaporative demands. The soil and twig water isotopic signal was depleted against current precipitation as it partly retained the isotopic signature from winter precipitation however the seasonal pattern of soil and twig water followed that of precipitation. No significant differences between sun-exposed and shaded samples were detected. Nevertheless, the observed strong seasonal pattern of isotope composition of leaf, twig and soil water should be taken into account when using leaf water enrichment for further calculations or modeling.
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Affiliation(s)
- Lenka Plavcová
- University of Hradec Králové, Faculty of Science, Rokitanského 62, CZ-50003, Hradec Králové, Czech Republic
| | - Marie Hronková
- University of South Bohemia, Faculty of Science, Branišovská 31, CZ-37005, České Budějovice, Czech Republic; Institute of Plant Molecular Biology, Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005, České Budějovice, Czech Republic
| | - Marie Šimková
- Institute of Plant Molecular Biology, Academy of Sciences of the Czech Republic, Branišovská 31, CZ-37005, České Budějovice, Czech Republic
| | - Jiří Květoň
- University of South Bohemia, Faculty of Science, Branišovská 31, CZ-37005, České Budějovice, Czech Republic
| | - Martina Vráblová
- University of South Bohemia, Faculty of Science, Branišovská 31, CZ-37005, České Budějovice, Czech Republic; VSB - Technical University of Ostrava, Institute of Environmental Technology, 17. listopadu 15, CZ-70833, Ostrava, Czech Republic
| | - Jiří Kubásek
- University of South Bohemia, Faculty of Science, Branišovská 31, CZ-37005, České Budějovice, Czech Republic
| | - Jiří Šantrůček
- University of South Bohemia, Faculty of Science, Branišovská 31, CZ-37005, České Budějovice, Czech Republic.
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16
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Thoma M, Frentress J, Tagliavini M, Scandellari F. Comparison of pore water samplers and cryogenic distillation under laboratory and field conditions for soil water stable isotope analysis. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2018; 54:403-417. [PMID: 29446985 DOI: 10.1080/10256016.2018.1437034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 01/15/2018] [Indexed: 06/08/2023]
Abstract
We used pore water samplers (PWS) to sample for isotope analysis (1) only water, (2) soil under laboratory conditions, and (3) soil in the field comparing the results with cryogenic extraction (CE). In (1) and (2), no significant differences between source and water extracted with PWS were detected with a mean absolute difference (MAD) always lower than 2 ‰ for δ2H and 1 ‰ for δ18O. In (2), CE water was more enriched than PWS-extracted water, with a MAD respect to source water of roughly 8 ‰ for δ2H and 4 ‰ for δ18O. In (3), PWS water was enriched relative to CE water by 3 ‰ for δ2H and 0.9 ‰ for δ18O. The latter result may be due to the distinct water portions sampled by the two methods. Large pores, easily sampled by PWS, likely retain recent, and enriched, summer precipitation while small pores, only sampled by CE, possibly retain isotopically depleted water from previous winter precipitation or irrigation inputs. Accuracy and precision were greater for PWS relative to CE. PWS is therefore suggested as viable tool to extract soil water for stable isotope analysis, particularly for soils used in this study (sandy and silty loams).
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Affiliation(s)
- Michael Thoma
- a Faculty of Science and Technology , Free University of Bozen-Bolzano, Bozen , Italy
| | - Jay Frentress
- a Faculty of Science and Technology , Free University of Bozen-Bolzano, Bozen , Italy
| | - Massimo Tagliavini
- a Faculty of Science and Technology , Free University of Bozen-Bolzano, Bozen , Italy
| | - Francesca Scandellari
- a Faculty of Science and Technology , Free University of Bozen-Bolzano, Bozen , Italy
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17
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A multiple time scale modeling investigation of leaf water isotope enrichment in a temperate grassland ecosystem. Ecol Res 2018. [DOI: 10.1007/s11284-018-1591-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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18
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Prieto I, Querejeta JI, Segrestin J, Volaire F, Roumet C. Leaf carbon and oxygen isotopes are coordinated with the leaf economics spectrum in Mediterranean rangeland species. Funct Ecol 2017. [DOI: 10.1111/1365-2435.13025] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Iván Prieto
- CEFECNRSUniv MontpellierUniv Paul Valéry Montpellier 3EPHEIRD Montpellier France
- Centro de Edafología y Biología Aplicada del Segura‐Consejo Superior de Investigaciones Científicas (CEBAS‐CSIC) Murcia Spain
| | - José I. Querejeta
- Centro de Edafología y Biología Aplicada del Segura‐Consejo Superior de Investigaciones Científicas (CEBAS‐CSIC) Murcia Spain
| | - Jules Segrestin
- CEFECNRSUniv MontpellierUniv Paul Valéry Montpellier 3EPHEIRD Montpellier France
| | - Florence Volaire
- CEFEINRACNRSUniv. MontpellierUniv Paul Valéry Montpellier 3EPHEIRD Montpellier France
| | - Catherine Roumet
- CEFECNRSUniv MontpellierUniv Paul Valéry Montpellier 3EPHEIRD Montpellier France
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19
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Liu J, An Z, Wang Z, Wu H. Using δD n-alkane as a proxy for paleo-environmental reconstruction: A good choice to sample at the site dominated by woods. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 599-600:554-559. [PMID: 28494281 DOI: 10.1016/j.scitotenv.2017.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 02/14/2017] [Accepted: 05/01/2017] [Indexed: 06/07/2023]
Abstract
Some studies have demonstrated that leaf wax δDn-alkane values for a single species varied significantly with seasons. However, it is still not clear that the seasonality patterns of leaf wax δDn-alkane values in higher plants. Meanwhile, few efforts have been pursued to assess the effect of the light slopes (sunny vs. cloudy) on leaf wax δDn-alkane values. In this study, we systematically investigated plant wax δDn-alkane values and soil n-alkane δD values along different light slopes in different seasons (spring vs. autumn), as well as the relationship of n-alkane δD values between plant leaves and soil. We found that plant wax δDn-alkane values were D-enriched by ca. 20‰ in spring relative to autumn, and ca. 10‰ in the sunny slope than in the cloudy slope. Moreover, surface soil n-alkane δD values varied consistently with plant wax δDn-alkane values for different seasons and light slopes. More importantly, plant wax δDn-alkane values showed clear seasonal variations, but varied slightly with light slopes. The variations of plant wax δDn-alkane values can be recorded in soil n-alkane δDn-alkane values. In addition, we found that leaf wax δDn-alkane values in a majority of species differed significantly among woods, non-woods and grasses at a site. Therefore, we suggested a good choice to sample at the site dominated by woods when leaf wax δDn-alkane values are utilized as a proxy for the reconstruction of the paleoenvironment.
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Affiliation(s)
- Jinzhao Liu
- School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an 710049, China; State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710075, China.
| | - Zhisheng An
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710075, China
| | - Zheng Wang
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710075, China
| | - Huawu Wu
- Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
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20
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Gerlein-Safdi C, Gauthier PPG, Sinkler CJ, Caylor KK. Leaf water 18 O and 2 H maps show directional enrichment discrepancy in Colocasia esculenta. PLANT, CELL & ENVIRONMENT 2017; 40:2095-2108. [PMID: 28658718 DOI: 10.1111/pce.13002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 05/31/2017] [Accepted: 06/02/2017] [Indexed: 06/07/2023]
Abstract
Spatial patterns of leaf water isotopes are challenging to predict because of the intricate link between vein and lamina water. Many models have attempted to predict these patterns, but to date, most have focused on monocots with parallel veins. These provide a simple system to study, but do not represent the majority of plant species. Here, a new protocol is developed using a Picarro induction module coupled to a cavity ringdown spectrometer to obtain maps of the leaf water isotopes (18 O and 2 H). The technique is applied to Colocasia esculenta leaves. The results are compared with isotope ratio mass spectrometry. In C. esculenta, a large enrichment in the radial direction is observed, but not in the longitudinal direction. The string-of-lakes model fails to predict the observed patterns, while the Farquhar-Gan model is more successful, especially when enrichment is accounted for along the radial direction. Our results show that reticulate-veined leaves experience a larger enrichment along the axis of the secondary veins than along the midrib. We hypothesize that this is due to the lower major/minor vein ratio that leads to longer pathways between major veins and sites of evaporation.
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Affiliation(s)
- Cynthia Gerlein-Safdi
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Paul P G Gauthier
- Department of Geosciences, Princeton University, Princeton, NJ, 08544, USA
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Craig James Sinkler
- Department of Geological, Environmental, and Marine Sciences, Rider University, Lawrenceville, NJ, 08648, USA
- EarthRes Group Inc., Pipersville, PA, 18947, USA
| | - Kelly Krispin Caylor
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, 08544, USA
- Department of Geography, UC Santa Barbara, Santa Barbara, CA, 93106, USA
- Bren School of Environmental Science and Management, UC Santa Barbara, Santa Barbara, CA, 93106, USA
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21
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Bögelein R, Thomas FM, Kahmen A. Leaf water 18 O and 2 H enrichment along vertical canopy profiles in a broadleaved and a conifer forest tree. PLANT, CELL & ENVIRONMENT 2017; 40:1086-1103. [PMID: 28042668 DOI: 10.1111/pce.12895] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 12/16/2016] [Accepted: 12/28/2016] [Indexed: 06/06/2023]
Abstract
Distinguishing meteorological and plant-mediated drivers of leaf water isotopic enrichment is prerequisite for ecological interpretations of stable hydrogen and oxygen isotopes in plant tissue. We measured input and leaf water δ2 H and δ18 O as well as micrometeorological and leaf morpho-physiological variables along a vertical gradient in a mature angiosperm (European beech) and gymnosperm (Douglas fir) tree. We used these variables and different enrichment models to quantify the influence of Péclet and non-steady state effects and of the biophysical drivers on leaf water enrichment. The two-pool model accurately described the diurnal variation of leaf water enrichment. The estimated unenriched water fraction was linked to leaf dry matter content across the canopy heights. Non-steady state effects and reduced stomatal conductance caused a higher enrichment of Douglas fir compared to beech leaf water. A dynamic effect analyses revealed that the light-induced vertical gradients of stomatal conductance and leaf temperature outbalanced each other in their effects on evaporative enrichment. We conclude that neither vertical canopy gradients nor the Péclet effect is important for estimates and interpretation of isotopic leaf water enrichment in hypostomatous trees. Contrarily, species-specific non-steady state effects and leaf temperatures as well as the water vapour isotope composition need careful consideration.
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Affiliation(s)
- Rebekka Bögelein
- Faculty of Regional and Environmental Sciences - Geobotany, University of Trier, 54296, Trier, Germany
| | - Frank M Thomas
- Faculty of Regional and Environmental Sciences - Geobotany, University of Trier, 54296, Trier, Germany
| | - Ansgar Kahmen
- Department of Environmental Sciences - Botany, University of Basel, 4056, Basel, Switzerland
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22
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Wernicke J, Hochreuther P, Grießinger J, Zhu H, Wang L, Bräuning A. Air mass origin signals in δ 18O of tree-ring cellulose revealed by back-trajectory modeling at the monsoonal Tibetan plateau. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2017; 61:1109-1124. [PMID: 28032196 DOI: 10.1007/s00484-016-1292-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 09/29/2016] [Accepted: 12/02/2016] [Indexed: 06/06/2023]
Abstract
A profound consideration of stable oxygen isotope source water origins is a precondition for an unambiguous palaeoenvironmental interpretation of terrestrial δ 18O archives. To stress the influence of air mass origins on widely used δ 18O tree-ring chronologies, we conducted correlation analyses between six annually resolved δ 18O tree-ring cellulose ([Formula: see text]) chronologies and mean annual air package origins obtained from backward trajectory modeling. This novel approach has been tested for a transect at the southeastern Tibetan plateau (TP), where air masses with different isotopic composition overlap. Detailed examinations of daily precipitation amounts and monthly precipitation δ 18O values ([Formula: see text]) were conducted with the ERA Interim and Laboratoire de Météorologie Dynamique General Circulation Model (LMDZiso) data, respectively. Particularly the southernmost study sites are influenced by a distinct amount effect. Here, air package origin [Formula: see text] relations are generally weaker in contrast to our northern located study sites. We found that tree-ring isotope signatures at dry sites with less rain days per year tend to be influenced stronger by air mass origin than tree-ring isotope values at semi-humid sites. That implies that the local hydroclimate history inferred from [Formula: see text] archives is better recorded at semi-humid sites.
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Affiliation(s)
- Jakob Wernicke
- Institute of Geography, University Erlangen-Nuremberg, Wetterkreuz 15, 91058, Erlangen, Germany.
| | - Philipp Hochreuther
- Institute of Geography, University Erlangen-Nuremberg, Wetterkreuz 15, 91058, Erlangen, Germany
| | - Jussi Grießinger
- Institute of Geography, University Erlangen-Nuremberg, Wetterkreuz 15, 91058, Erlangen, Germany
| | - Haifeng Zhu
- Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
| | - Lily Wang
- Institute of Geographical Sciences and Natural Resource Research, Chinese Academy of Sciences, Beijing, China
| | - Achim Bräuning
- Institute of Geography, University Erlangen-Nuremberg, Wetterkreuz 15, 91058, Erlangen, Germany
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Gamarra B, Kahmen A. Low secondary leaf wax n-alkane synthesis on fully mature leaves of C3 grasses grown at controlled environmental conditions and variable humidity. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2017; 31:218-226. [PMID: 27778411 DOI: 10.1002/rcm.7770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 10/17/2016] [Accepted: 10/17/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE Leaf wax n-alkanes are long-chained aliphatic compounds that are present in the cuticle of terrestrial plant leaves. Their δ2 H values are used for the reconstruction of past environments and for plant ecological investigations. The timing of n-alkane synthesis during leaf development and the rate of synthesis of secondary n-alkanes in fully matured leaves are still a matter of debate. METHODS Using a 2 H-labeling approach we estimated secondary leaf wax n-alkane synthesis rates in mature leaf blades of six C3 grass species grown in climate chambers under controlled environmental conditions. RESULTS We found that mature grass leaves continue the synthesis of leaf wax n-alkanes after leaf maturation. The rate of secondary n-alkanes synthesis was, however, relatively low and varied in response to atmospheric humidity and among species from 0.09 to 1.09% per day. CONCLUSIONS Our investigation provides new evidence on the timing of cuticular wax synthesis in grass leaves and indicates that the majority of n-alkanes are synthesized during the initial development of the leaf. Our study will improve the interpretation of leaf wax n-alkane δ2 H values in environmental and geological studies as it suggests that secondary synthesis of leaf wax n-alkanes in grass leaves contributes only slightly to the geological record. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Bruno Gamarra
- Department of Environmental Systems Sciences, ETH Zürich, Switzerland
- Department of Environmental Sciences - Botany, University of Basel, Switzerland
| | - Ansgar Kahmen
- Department of Environmental Sciences - Botany, University of Basel, Switzerland
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Gamarra B, Sachse D, Kahmen A. Effects of leaf water evaporative 2 H-enrichment and biosynthetic fractionation on leaf wax n-alkane δ 2 H values in C3 and C4 grasses. PLANT, CELL & ENVIRONMENT 2016; 39:2390-2403. [PMID: 27392279 DOI: 10.1111/pce.12789] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 06/14/2016] [Accepted: 06/14/2016] [Indexed: 06/06/2023]
Abstract
Leaf wax n-alkane δ2 H values carry important information about environmental and ecophysiological processes in plants. However, the physiological and biochemical drivers that shape leaf wax n-alkane δ2 H values are not completely understood. It is particularly unclear why n-alkanes in grasses are typically 2 H-depleted compared with plants from other taxonomic groups such as dicotyledonous plants and why C3 grasses are 2 H-depleted compared with C4 grasses. To resolve these uncertainties, we quantified the effects of leaf water evaporative 2 H-enrichment and biosynthetic hydrogen isotope fractionation on n-alkane δ2 H values for a range of C3 and C4 grasses grown in climate-controlled chambers. We found that only a fraction of leaf water evaporative 2 H-enrichment is imprinted on the leaf wax n-alkane δ2 H values in grasses. This is interesting, as previous studies have shown in dicotyledonous plants a nearly complete transfer of this 2 H-enrichment to the n-alkane δ2 H values. We thus infer that the typically observed 2 H-depletion of n-alkanes in grasses (as opposed to dicots) is because only a fraction of the leaf water evaporative 2 H-enrichment is imprinted on the δ2 H values. Our experiments also show that differences in n-alkane δ2 H values between C3 and C4 grasses are largely the result of systematic differences in biosynthetic fractionation between these two plant groups, which was on average -198‰ and-159‰ for C3 and C4 grasses, respectively.
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Affiliation(s)
- B Gamarra
- Department of Environmental Systems Sciences, ETH Zürich, 8092, Zurich, Switzerland.
- Department of Environmental Sciences - Botany, University of Basel, 4003, Basel, Switzerland.
| | - D Sachse
- Institut für Erd- und Umweltwissenschaften, Universität Potsdam, 144969, Potsdam, Germany
- Section 5.1: Geomorphology, Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences, 14473, Potsdam, Germany
| | - A Kahmen
- Department of Environmental Sciences - Botany, University of Basel, 4003, Basel, Switzerland
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Holloway-Phillips M, Cernusak LA, Barbour M, Song X, Cheesman A, Munksgaard N, Stuart-Williams H, Farquhar GD. Leaf vein fraction influences the Péclet effect and 18 O enrichment in leaf water. PLANT, CELL & ENVIRONMENT 2016; 39:2414-2427. [PMID: 27391079 DOI: 10.1111/pce.12792] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 06/22/2016] [Accepted: 06/23/2016] [Indexed: 06/06/2023]
Abstract
The process of evaporation results in the fractionation of water isotopes such that the lighter 16 O isotope preferentially escapes the gas phase leaving the heavier 18 O isotope to accumulate at the sites of evaporation. This applies to transpiration from a leaf with the degree of fractionation dependent on a number of environmental and physiological factors that are well understood. Nevertheless, the 18 O enrichment of bulk leaf water is often less than that predicted for the sites of evaporation. The advection of less enriched water in the transpiration stream has been suggested to limit the back diffusion of enriched evaporative site water (Péclet effect); however, evidence for this effect has been varied. In sampling across a range of species with different vein densities and saturated water contents, we demonstrate the importance of accounting for the relative 'pool' sizes of the vascular and mesophyll water for the interpretation of a Péclet effect. Further, we provide strong evidence for a Péclet signal within the xylem that if unaccounted for can lead to confounding of the estimated enrichment within the mesophyll water. This has important implications for understanding variation in the effective path length of the mesophyll and hence potentially the δ18 O of organic matter.
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Affiliation(s)
- Meisha Holloway-Phillips
- Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia.
| | - Lucas A Cernusak
- College of Science and Engineering, James Cook University, Cairns, Queensland, Australia
| | - Margaret Barbour
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, Camden, New South Wales, Australia
| | - Xin Song
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, Camden, New South Wales, Australia
| | - Alexander Cheesman
- College of Science and Engineering, James Cook University, Cairns, Queensland, Australia
| | - Niels Munksgaard
- College of Science and Engineering, James Cook University, Cairns, Queensland, Australia
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory, Australia
| | - Hilary Stuart-Williams
- Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Graham D Farquhar
- Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
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Song X, Barbour MM. Leaf water oxygen isotope measurement by direct equilibration. THE NEW PHYTOLOGIST 2016; 211:1120-1128. [PMID: 27147584 DOI: 10.1111/nph.13962] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 03/07/2016] [Indexed: 06/05/2023]
Abstract
The oxygen isotope composition of leaf water imparts a signal to a range of molecules in the atmosphere and biosphere, but has been notoriously difficult to measure in studies requiring a large number of samples as a consequence of the labour-intensive extraction step. We tested a method of direct equilibration of water in fresh leaf samples with CO2 , and subsequent oxygen isotope analysis on an optical spectrometer. The oxygen isotope composition of leaf water measured by the direct equilibration technique was strongly linearly related to that of cryogenically extracted leaf water in paired samples for a wide range of species with differing anatomy, with an R(2) of 0.95. The somewhat more enriched values produced by the direct equilibration method may reflect lack of full equilibration with unenriched water in the vascular bundles, but the strong relationship across a wide range of species suggests that this difference can be adequately corrected for using a simple linear relationship.
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Affiliation(s)
- Xin Song
- Centre for Carbon, Water and Food, The University of Sydney, 380 Werombi Road, Brownlow Hill, NSW, 2570, Australia
| | - Margaret M Barbour
- Centre for Carbon, Water and Food, The University of Sydney, 380 Werombi Road, Brownlow Hill, NSW, 2570, Australia
- Landcare Research, PO Box 40, Lincoln, 7640, New Zealand
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27
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Cernusak LA, Barbour MM, Arndt SK, Cheesman AW, English NB, Feild TS, Helliker BR, Holloway-Phillips MM, Holtum JAM, Kahmen A, McInerney FA, Munksgaard NC, Simonin KA, Song X, Stuart-Williams H, West JB, Farquhar GD. Stable isotopes in leaf water of terrestrial plants. PLANT, CELL & ENVIRONMENT 2016; 39:1087-102. [PMID: 26715126 DOI: 10.1111/pce.12703] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 11/21/2015] [Accepted: 12/16/2015] [Indexed: 05/14/2023]
Abstract
Leaf water contains naturally occurring stable isotopes of oxygen and hydrogen in abundances that vary spatially and temporally. When sufficiently understood, these can be harnessed for a wide range of applications. Here, we review the current state of knowledge of stable isotope enrichment of leaf water, and its relevance for isotopic signals incorporated into plant organic matter and atmospheric gases. Models describing evaporative enrichment of leaf water have become increasingly complex over time, reflecting enhanced spatial and temporal resolution. We recommend that practitioners choose a model with a level of complexity suited to their application, and provide guidance. At the same time, there exists some lingering uncertainty about the biophysical processes relevant to patterns of isotopic enrichment in leaf water. An important goal for future research is to link observed variations in isotopic composition to specific anatomical and physiological features of leaves that reflect differences in hydraulic design. New measurement techniques are developing rapidly, enabling determinations of both transpired and leaf water δ(18) O and δ(2) H to be made more easily and at higher temporal resolution than previously possible. We expect these technological advances to spur new developments in our understanding of patterns of stable isotope fractionation in leaf water.
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Affiliation(s)
- Lucas A Cernusak
- College of Marine and Environmental Sciences, James Cook University, Cairns, Australia
| | - Margaret M Barbour
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, Camden, Australia
| | - Stefan K Arndt
- School of Ecosystem and Forest Sciences, The University of Melbourne, Richmond, Australia
| | - Alexander W Cheesman
- College of Marine and Environmental Sciences, James Cook University, Cairns, Australia
| | - Nathan B English
- College of Marine and Environmental Sciences, James Cook University, Townsville, Australia
| | - Taylor S Feild
- College of Marine and Environmental Sciences, James Cook University, Townsville, Australia
| | - Brent R Helliker
- Department of Biology, University of Pennsylvania, Philadelphia, USA
| | | | - Joseph A M Holtum
- College of Marine and Environmental Sciences, James Cook University, Townsville, Australia
| | - Ansgar Kahmen
- Department of Environmental Sciences-Botany, University of Basel, Basel, Switzerland
| | | | - Niels C Munksgaard
- College of Science, Technology and Engineering, James Cook University, Cairns, Australia
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Australia
| | - Kevin A Simonin
- Department of Biology, San Francisco State University, San Francisco, USA
| | - Xin Song
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, Camden, Australia
| | | | - Jason B West
- Department of Ecosystem Science and Management, Texas A&M University, College Station, USA
| | - Graham D Farquhar
- Research School of Biology, The Australian National University, Canberra, Australia
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Roden J, Kahmen A, Buchmann N, Siegwolf R. The enigma of effective path length for (18) O enrichment in leaf water of conifers. PLANT, CELL & ENVIRONMENT 2015; 38:2551-2565. [PMID: 26037826 DOI: 10.1111/pce.12568] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Revised: 05/02/2015] [Accepted: 05/04/2015] [Indexed: 06/04/2023]
Abstract
The Péclet correction is often used to predict leaf evaporative enrichment and requires an estimate of effective path length (L). Studies to estimate L in conifer needles have produced unexpected patterns based on Péclet theory and leaf anatomy. We exposed seedlings of six conifer species to different vapour pressure deficits (VPD) in controlled climate chambers to produce steady-state leaf water enrichment (in (18) O). We measured leaf gas exchange, stable oxygen isotopic composition (δ(18) O) of input and plant waters as well as leaf anatomical characteristics. Variation in bulk needle water δ(18) O was strongly related to VPD. Conifer needles had large amounts of water within the vascular strand that was potentially unenriched (up to 40%). Both standard Craig-Gordon and Péclet models failed to accurately predict conifer leaf water δ(18) O without taking into consideration the unenriched water in the vascular strand and variable L. Although L was linearly related to mesophyll thickness, large within-species variation prevented the development of generalizations that could allow a broader use of the Péclet effect in predictive models. Our results point to the importance of within needle water pools and isolating mechanisms that need further investigation in order to integrate Péclet corrections with 'two compartment' leaf water concepts.
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Affiliation(s)
- John Roden
- Department of Biology, Southern Oregon University, Ashland, OR, 97520, USA
| | - Ansgar Kahmen
- Department of Environmental Sciences - Botany, University of Basel, 4056, Basel, Switzerland
| | - Nina Buchmann
- Department of Environmental Systems Science, Eidgenössische Technische Hochschule, 8092, Zürich
| | - Rolf Siegwolf
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, 5232, Villigen, Switzerland
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29
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Song X, Simonin KA, Loucos KE, Barbour MM. Modelling non-steady-state isotope enrichment of leaf water in a gas-exchange cuvette environment. PLANT, CELL & ENVIRONMENT 2015; 38:2618-2628. [PMID: 25993893 DOI: 10.1111/pce.12571] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 05/16/2015] [Accepted: 05/16/2015] [Indexed: 06/04/2023]
Abstract
The combined use of a gas-exchange system and laser-based isotope measurement is a tool of growing interest in plant ecophysiological studies, owing to its relevance for assessing isotopic variability in leaf water and/or transpiration under non-steady-state (NSS) conditions. However, the current Farquhar & Cernusak (F&C) NSS leaf water model, originally developed for open-field scenarios, is unsuited for use in a gas-exchange cuvette environment where isotope composition of water vapour (δv ) is intrinsically linked to that of transpiration (δE ). Here, we modified the F&C model to make it directly compatible with the δv -δE dynamic characteristic of a typical cuvette setting. The resultant new model suggests a role of 'net-flux' (rather than 'gross-flux' as suggested by the original F&C model)-based leaf water turnover rate in controlling the time constant (τ) for the approach to steady sate. The validity of the new model was subsequently confirmed in a cuvette experiment involving cotton leaves, for which we demonstrated close agreement between τ values predicted from the model and those measured from NSS variations in isotope enrichment of transpiration. Hence, we recommend that our new model be incorporated into future isotope studies involving a cuvette condition where the transpiration flux directly influences δv . There is an increasing popularity among plant ecophysiologists to use a gas-exchange system coupled to laser-based isotope measurement for investigating non-steady state (NSS) isotopic variability in leaf water (and/or transpiration); however, the current Farquhar & Cernusak (F&C) NSS leaf water model is unsuited for use in a gas-exchange cuvette environment due to its implicit assumption of isotope composition of water vapor (δv ) being constant and independent of that of transpiration (δE ). In the present study, we modified the F&C model to make it compatible with the dynamic relationship between δv and δE as is typically associated with a cuvette setting. Using an experiment conducted on cotton leaves, we show that the modified NSS model performed well in predicting the time constant for the exponential approach of leaf water toward steady state under cuvette conditions. Such a result demonstrates the applicability of this new model to gas-exchange cuvette conditions where the transpiration flux directly influences δv , and therefore suggests the need to incorporate this model into future isotope studies that employ a laser-cuvette coupled system.
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Affiliation(s)
- Xin Song
- Faculty of Agriculture and Environment, University of Sydney, Private Bag 4110, Narellan, New South Wales, 2567, Australia
| | - Kevin A Simonin
- Faculty of Agriculture and Environment, University of Sydney, Private Bag 4110, Narellan, New South Wales, 2567, Australia
| | - Karen E Loucos
- Faculty of Agriculture and Environment, University of Sydney, Private Bag 4110, Narellan, New South Wales, 2567, Australia
| | - Margaret M Barbour
- Faculty of Agriculture and Environment, University of Sydney, Private Bag 4110, Narellan, New South Wales, 2567, Australia
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30
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Ladd SN, Sachs JP. Hydrogen isotope response to changing salinity and rainfall in Australian mangroves. PLANT, CELL & ENVIRONMENT 2015; 38:2674-2687. [PMID: 26013204 DOI: 10.1111/pce.12579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 05/19/2015] [Accepted: 05/19/2015] [Indexed: 06/04/2023]
Abstract
Hydrogen isotope ratios ((2) H/(1) H, δ(2) H) of leaf waxes covary with those in precipitation and are therefore a useful paleohydrologic proxy. Mangroves are an exception to this relationship because their δ(2) H values are also influenced by salinity. The mechanisms underlying this response were investigated by measuring leaf lipid δ(2) H and leaf and xylem water δ(2) H and δ(18) O values from three mangrove species over 9.5 months in a subtropical Australian estuary. Net (2) H/(1) H fractionation between surface water and leaf lipids decreased by 0.5-1.0‰ ppt(-1) for n-alkanes and 0.4-0.8‰ ppt(-1) for isoprenoids. Xylem water was (2) H depleted relative to surface water, reflecting (2) H discrimination of 4-10‰ during water uptake at all salinities and opportunistic uptake of freshwater at high salinity. However, leaf water (2) H enrichment relative to estuary water was insensitive to salinity and identical for all species. Therefore, variations in leaf and xylem water δ(2) H values cannot explain the salinity-dependent (2) H depletion in leaf lipids, nor the 30‰ range in leaf lipid δ(2) H values among species. Biochemical changes in direct response to salt stress, such as increased compatible solute production or preferential use of stored carbohydrates, and/or the timing of lipid production and subsequent turnover rates, are more likely causes.
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Affiliation(s)
- S Nemiah Ladd
- School of Oceanography, University of Washington, Box 355315, Seattle, WA, 98195, USA.
| | - Julian P Sachs
- School of Oceanography, University of Washington, Box 355315, Seattle, WA, 98195, USA
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Life form-specific gradients in compound-specific hydrogen isotope ratios of modern leaf waxes along a North American Monsoonal transect. Oecologia 2015; 179:981-97. [DOI: 10.1007/s00442-015-3432-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 08/15/2015] [Indexed: 10/23/2022]
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Arndt SK, Sanders GJ, Bristow M, Hutley LB, Beringer J, Livesley SJ. Vulnerability of native savanna trees and exotic Khaya senegalensis to seasonal drought. TREE PHYSIOLOGY 2015; 35:783-791. [PMID: 25934988 DOI: 10.1093/treephys/tpv037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 04/06/2015] [Indexed: 06/04/2023]
Abstract
Seasonally dry ecosystems present a challenge to plants to maintain water relations. While native vegetation in seasonally dry ecosystems have evolved specific adaptations to the long dry season, there are risks to introduced exotic species. African mahogany, Khaya senegalensis Desr. (A. Juss.), is an exotic plantation species that has been introduced widely in Asia and northern Australia, but it is unknown if it has the physiological or phenotypic plasticity to cope with the strongly seasonal patterns of water availability in the tropical savanna climate of northern Australia. We investigated the gas exchange and water relations traits and adjustments to seasonal drought in K. senegalensis and native eucalypts (Eucalyptus tetrodonta F. Muell. and Corymbia latifolia F. Muell.) in a savanna ecosystem in northern Australia. The native eucalypts did not exhibit any signs of drought stress after 3 months of no rainfall and probably had access to deeper soil moisture late into the dry season. Leaf water potential, stomatal conductance, transpiration and photosynthesis all remained high in the dry season but osmotic adjustment was not observed. Overstorey leaf area index (LAI) was 0.6 in the native eucalypt savanna and did not change between wet and dry seasons. In contrast, the K. senegalensis plantation in the wet season was characterized by a high water potential, high stomatal conductance and transpiration and a high LAI of 2.4. In the dry season, K. senegalensis experienced mild drought stress with a predawn water potential -0.6 MPa. Overstorey LAI was halved, and stomatal conductance and transpiration drastically reduced, while minimum leaf water potentials did not change (-2 MPa) and no osmotic adjustment occurred. Khaya senegalensis exhibited an isohydric behaviour and also had a lower hydraulic vulnerability to cavitation in leaves, with a P50 of -2.3 MPa. The native eucalypts had twice the maximum leaf hydraulic conductance but a much higher P50 of -1.5 MPa. Khaya senegalensis has evolved in a wet-dry tropical climate in West Africa (600-800 mm) and appears to be well suited to the seasonal savanna climate of northern Australia. The species exhibited a large phenotypic plasticity through leaf area adjustments and conservative isohydric behaviour in the 6 months dry season while operating well above its critical hydraulic threshold.
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Affiliation(s)
- Stefan K Arndt
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, VIC 3121, Australia Terrestrial Ecosystem Research, Department of Microbiology and Ecosystem Science, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Gregor J Sanders
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, VIC 3121, Australia
| | - Mila Bristow
- School of Environment, Charles Darwin University, Casuarina, NT 0810, Australia
| | - Lindsay B Hutley
- School of Environment, Charles Darwin University, Casuarina, NT 0810, Australia
| | - Jason Beringer
- School of Earth and Environment, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Stephen J Livesley
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, VIC 3121, Australia
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Tipple BJ, Berke MA, Hambach B, Roden JS, Ehleringer JR. Predicting leaf wax n-alkane 2H/1H ratios: controlled water source and humidity experiments with hydroponically grown trees confirm predictions of Craig-Gordon model. PLANT, CELL & ENVIRONMENT 2015; 38:1035-1047. [PMID: 25266328 DOI: 10.1111/pce.12457] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 09/11/2014] [Accepted: 09/23/2014] [Indexed: 06/03/2023]
Abstract
The extent to which both water source and atmospheric humidity affect δ(2)H values of terrestrial plant leaf waxes will affect the interpretations of δ(2)H variation of leaf waxes as a proxy for hydrological conditions. To elucidate the effects of these parameters, we conducted a long-term experiment in which we grew two tree species, Populus fremontii and Betula occidentalis, hydroponically under combinations of six isotopically distinct waters and two different atmospheric humidities. We observed that leaf n-alkane δ(2)H values of both species were linearly related to source water δ(2)H values, but with slope differences associated with differing humidities. When a modified version of the Craig-Gordon model incorporating plant factors was used to predict the δ(2)H values of leaf water, all modelled leaf water values fit the same linear relationship with n-alkane δ(2)H values. These observations suggested a relatively constant biosynthetic fractionation factor between leaf water and n-alkanes. However, our calculations indicated a small difference in the biosynthetic fractionation factor between the two species, consistent with small differences calculated for species in other studies. At present, it remains unclear if these apparent interspecies differences in biosynthetic fractionation reflect species-specific biochemistry or a common biosynthetic fractionation factor with insufficient model parameterization.
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Affiliation(s)
- Brett J Tipple
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA; Global Change and Sustainability Center, University of Utah, Salt Lake City, UT, 84112, USA
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Larcher L, Hara-Nishimura I, Sternberg L. Effects of stomatal density and leaf water content on the ¹⁸O enrichment of leaf water. THE NEW PHYTOLOGIST 2015; 206:141-151. [PMID: 25408145 DOI: 10.1111/nph.13154] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 10/07/2014] [Indexed: 06/04/2023]
Abstract
Leaf water isotopic composition is imprinted in several biomarkers of interest and it is imperative that we understand the isotopic enrichment of leaf water. Here, we test the effect of stomatal density and leaf water content on the oxygen isotopic composition of leaf water in transgenic Arabidopsis plants expressing different stomatal densities, and several other species showing a range of stomatal density. We grew Arabidopsis plants hydroponically and collected other species in the field. Stomatal density and leaf water content were determined for each plant. We measured transpiration and extracted leaf water for isotopic determination. Using these measurements and the current leaf water isotope model, we calculated several of the parameters related to leaf water isotopic enrichment. High stomatal density promoted leaf water isotope enrichment. No conclusion, however, can be drawn regarding the effect of leaf water content on leaf water isotope enrichment. Factors such as transpiration might mask the effect of stomatal density on leaf water isotopic enrichment. We propose a method by which stomatal density can be incorporated in the current Peclet model of leaf water isotope enrichment. These findings have important applications in the use of plant-based metabolic proxies in paleoclimate studies.
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Affiliation(s)
- Leticia Larcher
- Programa de Pós Graduação em Ecologia e Conservação, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
| | - Ikuko Hara-Nishimura
- Graduate School of Science, Department of Botany, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Leonel Sternberg
- Department of Biology, University of Miami, 1301 Memorial Drive, Coral Gables, FL, 33124, USA
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36
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Loucos KE, Simonin KA, Song X, Barbour MM. Observed relationships between leaf H218O Péclet effective length and leaf hydraulic conductance reflect assumptions in Craig-Gordon model calculations. TREE PHYSIOLOGY 2015; 35:16-26. [PMID: 25576755 DOI: 10.1093/treephys/tpu110] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Stable oxygen isotope techniques may be a useful tool to investigate the pathways of water movement within leaves. However, implementation of such methods is limited due to uncertainty in the effective path length (L) for the Péclet effect in leaf water enrichment models. Previous studies have found relationships between L and physiological parameters such as transpiration rate (E) and leaf hydraulic conductance (k(leaf)) both within and between species. However, these studies relied on assumptions in their calculation of L, which were not directly tested. Eucalyptus paniculata Smith was used to evaluate the relationships between L, k(leaf) and E under differing water availability and a range of leaf temperatures. Coupled gas exchange and transpiration isotope measurements allowed previous assumptions to be directly tested. L was significantly and negatively related to both k(leaf) and E when the isotopic signature of water vapour was assumed to be in equilibrium with source water, was equivalent to the room vapour or equal to source water. However, the relationship between L and k(leaf) was non-significant when measured δ( 18)O of transpired vapour was used and disappeared entirely when non-steady-state leaves were excluded, and when evaporation site water was calculated from coupled gas exchange and transpiration isotope values. These results suggest that great care must be taken when calculating L, particularly regarding assumptions of isotopic steady state and δ( 18)O of vapour. Previous suggestions of changes in pathways for water movement as transpiration rate varied need to be reassessed in light of these observations.
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Affiliation(s)
- Karen E Loucos
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Rd, NSW 2570, Australia
| | - Kevin A Simonin
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Rd, NSW 2570, Australia Current address: Department of Biology, San Francisco State University, San Francisco, CA 94132, USA
| | - Xin Song
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Rd, NSW 2570, Australia
| | - Margaret M Barbour
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Rd, NSW 2570, Australia
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Song X, Clark KS, Helliker BR. Interpreting species-specific variation in tree-ring oxygen isotope ratios among three temperate forest trees. PLANT, CELL & ENVIRONMENT 2014; 37:2169-82. [PMID: 24588709 DOI: 10.1111/pce.12317] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 02/24/2014] [Accepted: 02/25/2014] [Indexed: 05/13/2023]
Abstract
Although considerable variation has been documented in tree-ring cellulose oxygen isotope ratios (δ(18)O(cell)) among co-occurring species, the underlying causes are unknown. Here, we used a combination of field measurements and modelling to investigate the mechanisms behind variations in late-wood δ(18) O(cell) (δ(18)O(lc)) among three co-occurring species (chestnut oak, black oak and pitch pine) in a temperate forest. For two growing seasons, we quantified among-species variation in δ(18)O(lc), as well as several variables that could potentially cause the δ(18)O(lc) variation. Data analysis based on the δ(18) O(cell) model rules out leaf water enrichment (Δ(18)O(lw)) and tree-ring formation period (Δt), but highlights source water δ(18) O (δ(18) O(sw)) as an important driver for the measured difference in δ(18)O(lc) between black and chestnut oak. However, the enriched δ(18)O(lc) in pitch pine relative to the oaks could not be sufficiently explained by consideration of the above three variables only, but rather, we show that differences in the proportion of oxygen exchange during cellulose synthesis (p(ex)) is most likely a key mechanism. Our demonstration of the relevance of some species-specific features (or lack thereof) to δ(18)O(cell) has important implications for isotope based ecophysiological/paleoclimate studies.
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Affiliation(s)
- Xin Song
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
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38
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Marias DE, Meinzer FC, Woodruff DR, Shaw DC, Voelker SL, Brooks JR, Lachenbruch B, Falk K, McKay J. Impacts of dwarf mistletoe on the physiology of host Tsuga heterophylla trees as recorded in tree-ring C and O stable isotopes. TREE PHYSIOLOGY 2014; 34:595-607. [PMID: 24973917 DOI: 10.1093/treephys/tpu046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Dwarf mistletoes, obligate, parasitic plants with diminutive aerial shoots, have long-term effects on host tree water relations, hydraulic architecture and photosynthetic gas exchange and can eventually induce tree death. To investigate the long-term (1886-2010) impacts of dwarf mistletoe on the growth and gas exchange characteristics of host western hemlock, we compared the diameter growth and tree-ring cellulose stable carbon (C) and oxygen (O) isotope ratios (δ(13)Ccell, δ(18)Ocell) of heavily infected and uninfected trees. The relative basal area growth of infected trees was significantly greater than that of uninfected trees in 1886-90, but declined more rapidly in infected than uninfected trees through time and became significantly lower in infected than uninfected trees in 2006-10. Infected trees had significantly lower δ(13)Ccell and δ(18)Ocell than uninfected trees. Differences in δ(18)Ocell between infected and uninfected trees were unexpected given that stomatal conductance and environmental variables that were expected to influence the δ(18)O values of leaf water were similar for both groups. However, estimates of mesophyll conductance (gm) were significantly lower and estimates of effective path length for water movement (L) were significantly higher in leaves of infected trees, consistent with their lower values of δ(18)Ocell. This study reconstructs the long-term physiological responses of western hemlock to dwarf mistletoe infection. The long-term diameter growth and δ(13)Ccell trajectories suggested that infected trees were growing faster than uninfected trees prior to becoming infected and subsequently declined in growth and leaf-level photosynthetic capacity compared with uninfected trees as the dwarf mistletoe infection became severe. This study further points to limitations of the dual-isotope approach for identifying sources of variation in δ(13)Ccell and indicates that changes in leaf internal properties such as gm and L that affect δ(18)Ocell must be considered.
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Affiliation(s)
- Danielle E Marias
- Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, Corvallis, OR 97331, USA
| | - Frederick C Meinzer
- Pacific Northwest Research Station, USDA Forest Service, Corvallis, OR 97331, USA
| | - David R Woodruff
- Pacific Northwest Research Station, USDA Forest Service, Corvallis, OR 97331, USA
| | - David C Shaw
- Forest Engineering, Resources and Management, Oregon State University, 280 Peavy Hall, Corvallis, OR 97331, USA
| | - Steven L Voelker
- Biology Department, Southern Oregon University, 1250 Siskiyou Blvd, Ashland, OR 97520, USA
| | - J Renée Brooks
- Western Ecology Division, US EPANHEERL, Corvallis, OR 97331, USA
| | - Barbara Lachenbruch
- Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, Corvallis, OR 97331, USA
| | - Kristen Falk
- Forest Engineering, Resources and Management, Oregon State University, 280 Peavy Hall, Corvallis, OR 97331, USA
| | - Jennifer McKay
- College of Earth, Oceanic, and Atmospheric Sciences, Oregon State University, 104 CEOAS Administration Building, Corvallis, OR 97331, USA
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Helliker BR. Reconstructing the δ(18) O of atmospheric water vapour via the CAM epiphyte Tillandsia usneoides: seasonal controls on δ(18) O in the field and large-scale reconstruction of δ(18) Oa. PLANT, CELL & ENVIRONMENT 2014; 37:541-556. [PMID: 23889204 DOI: 10.1111/pce.12167] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Using both oxygen isotope ratios of leaf water (δ(18) OL ) and cellulose (δ(18) OC ) of Tillandsia usneoides in situ, this paper examined how short- and long-term responses to environmental variation and model parameterization affected the reconstruction of the atmospheric water vapour (δ(18) Oa ). During sample-intensive field campaigns, predictions of δ(18) OL matched observations well using a non-steady-state model, but the model required data-rich parameterization. Predictions from the more easily parameterized maximum enrichment model (δ(18) OL-M ) matched observed δ(18) OL and observed δ(18) Oa when leaf water turnover was less than 3.5 d. Using the δ(18) OL-M model and weekly samples of δ(18) OL across two growing seasons in Florida, USA, reconstructed δ(18) Oa was -12.6 ± 0.3‰. This is compared with δ(18) Oa of -12.4 ± 0.2‰ resolved from the growing-season-weighted δ(18) OC . Both of these values were similar to δ(18) Oa in equilibrium with precipitation, -12.9‰. δ(18) Oa was also reconstructed through a large-scale transect with δ(18) OL and the growing-season-integrated δ(18) OC across the southeastern United States. There was considerable large-scale variation, but there was regional, weather-induced coherence in δ(18) Oa when using δ(18) OL . The reconstruction of δ(18) Oa with δ(18) OC generally supported the assumption of δ(18) Oa being in equilibrium with precipitation δ(18) O (δ(18) Oppt ), but the pool of δ(18) Oppt with which δ(18) Oa was in equilibrium - growing season versus annual δ(18) Oppt - changed with latitude.
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Affiliation(s)
- Brent R Helliker
- Department of Biology, University of Pennsylvania, 433 S. University Ave, Philadelphia, PA, 19104, USA
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Simonin KA, Roddy AB, Link P, Apodaca R, Tu KP, Hu J, Dawson TE, Barbour MM. Isotopic composition of transpiration and rates of change in leaf water isotopologue storage in response to environmental variables. PLANT, CELL & ENVIRONMENT 2013; 36:2190-206. [PMID: 23647101 DOI: 10.1111/pce.12129] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 04/18/2013] [Accepted: 04/22/2013] [Indexed: 05/27/2023]
Abstract
During daylight hours, the isotope composition of leaf water generally approximates steady-state leaf water isotope enrichment model predictions. However, until very recently there was little direct confirmation that isotopic steady-state (ISS) transpiration in fact exists. Using isotope ratio infrared spectroscopy (IRIS) and leaf gas exchange systems we evaluated the isotope composition of transpiration and the rate of change in leaf water isotopologue storage (isostorage) when leaves were exposed to variable environments. In doing so, we developed a method for controlling the absolute humidity entering the gas exchange cuvette for a wide range of concentrations without changing the isotope composition of water vapour. The measurement system allowed estimation of (18)O enrichment both at the evaporation site and for bulk leaf water, in the steady state and the non-steady state. We show that non-steady-state effects dominate the transpiration isoflux even when leaves are at physiological steady state. Our results suggest that a variable environment likely prevents ISS transpiration from being achieved and that this effect may be exacerbated by lengthy leaf water turnover times due to high leaf water contents.
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Affiliation(s)
- Kevin A Simonin
- Faculty of Agriculture and Environment, University of Sydney, Sydney, NSW, 2570, Australia
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Gessler A, Brandes E, Keitel C, Boda S, Kayler ZE, Granier A, Barbour M, Farquhar GD, Treydte K. The oxygen isotope enrichment of leaf-exported assimilates--does it always reflect lamina leaf water enrichment? THE NEW PHYTOLOGIST 2013; 200:144-157. [PMID: 23763637 PMCID: PMC3902987 DOI: 10.1111/nph.12359] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 05/09/2013] [Indexed: 05/12/2023]
Abstract
The oxygen stable isotope composition of plant organic matter (OM) (particularly of wood and cellulose in the tree ring archive) is valuable in studies of plant-climate interaction, but there is a lack of information on the transfer of the isotope signal from the leaf to heterotrophic tissues. We studied the oxygen isotopic composition and its enrichment above source water of leaf water over diel courses in five tree species covering a broad range of life forms. We tracked the transfer of the isotopic signal to leaf water-soluble OM and further to phloem-transported OM. Observed leaf water evaporative enrichment was consistent with values predicted from mechanistic models taking into account nonsteady-state conditions. While leaf water-soluble OM showed the expected (18)O enrichment in all species, phloem sugars were less enriched than expected from leaf water enrichment in Scots pine (Pinus sylvestris), European larch (Larix decidua) and Alpine ash (Eucalyptus delegatensis). Oxygen atom exchange with nonenriched water during phloem loading and transport, as well as a significant contribution of assimilates from bark photosynthesis, can explain these phloem (18)O enrichment patterns. Our results indicate species-specific uncoupling between the leaf water and the OM oxygen isotope signal, which is important for the interpretation of tree ring data.
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Affiliation(s)
- Arthur Gessler
- Leibniz Centre for Agricultural Landscape Research, Institute for Landscape BiogeochemistryEberswalderstr. 84, 15374, Müncheberg, Germany
- INRA, UMR 1137 Ecologie et Ecophysiologie Forestières INRA/Université de Lorraine54280, Champenoux, France
- Research School of Biology, Australian National UniversityBuilding 46, Acton, ACT, 0200, Autralia
| | - Elke Brandes
- INRA, UMR 1137 Ecologie et Ecophysiologie Forestières INRA/Université de Lorraine54280, Champenoux, France
| | - Claudia Keitel
- Research School of Biology, Australian National UniversityBuilding 46, Acton, ACT, 0200, Autralia
- Faculty of Agriculture and Environment, University of SydneyPrivate Bag 4011, Narellan, NSW, 2567, Australia
| | - Sonja Boda
- Swiss Federal Research Institute WSL, Research Unit Landscape DynamicsZürcherstrasse 111, CH-8903, Birmensdorf, Switzerland
| | - Zachary E Kayler
- Leibniz Centre for Agricultural Landscape Research, Institute for Landscape BiogeochemistryEberswalderstr. 84, 15374, Müncheberg, Germany
| | - André Granier
- INRA, UMR 1137 Ecologie et Ecophysiologie Forestières INRA/Université de Lorraine54280, Champenoux, France
| | - Margaret Barbour
- Faculty of Agriculture and Environment, University of SydneyPrivate Bag 4011, Narellan, NSW, 2567, Australia
| | - Graham D Farquhar
- Research School of Biology, Australian National UniversityBuilding 46, Acton, ACT, 0200, Autralia
| | - Kerstin Treydte
- Swiss Federal Research Institute WSL, Research Unit Landscape DynamicsZürcherstrasse 111, CH-8903, Birmensdorf, Switzerland
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Rosado BHP, De Mattos EA, Sternberg LDSL. Are leaf physiological traits related to leaf water isotopic enrichment in restinga woody species? AN ACAD BRAS CIENC 2013; 85:1035-46. [PMID: 24068091 DOI: 10.1590/s0001-37652013005000051] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 08/23/2012] [Indexed: 11/22/2022] Open
Abstract
During plant-transpiration, water molecules having the lighter stable isotopes of oxygen and hydrogen evaporate and diffuse at a faster rate through the stomata than molecules having the heavier isotopes, which cause isotopic enrichment of leaf water. Although previous models have assumed that leaf water is well-mixed and isotopically uniform, non-uniform stomatal closure, promoting different enrichments between cells, and different pools of water within leaves, due to morpho-physiological traits, might lead to inaccuracies in isotopic models predicting leaf water enrichment. We evaluate the role of leaf morpho-physiological traits on leaf water isotopic enrichment in woody species occurring in a coastal vegetation of Brazil known as restinga. Hydrogen and oxygen stable isotope values of soil, plant stem and leaf water and leaf traits were measured in six species from restinga vegetation during a drought and a wet period. Leaf water isotopic enrichment relative to stem water was more homogeneous among species during the drought in contrast to the wet period suggesting convergent responses to deal to temporal heterogeneity in water availability. Average leaf water isotopic enrichment relative to stem water during the drought period was highly correlated with relative apoplastic water content. We discuss this observation in the context of current models of leaf water isotopic enrichment as a function of the Péclet effect. We suggest that future studies should include relative apoplastic water content in isotopic models.
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Affiliation(s)
- Bruno H P Rosado
- Departamento de Ecologia, IB, CCS, Universidade Federal do Rio de Janeiro, Av. Brigadeiro Trompowski, s/n, C.P. 68020, 21941-970 Rio de Janeiro, RJ, Brasil.
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43
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Song X, Barbour MM, Farquhar GD, Vann DR, Helliker BR. Transpiration rate relates to within- and across-species variations in effective path length in a leaf water model of oxygen isotope enrichment. PLANT, CELL & ENVIRONMENT 2013; 36:1338-1351. [PMID: 23305086 DOI: 10.1111/pce.12063] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 12/15/2012] [Accepted: 12/17/2012] [Indexed: 06/01/2023]
Abstract
Stable oxygen isotope ratio of leaf water (δ(18)O(L)) yields valuable information on many aspects of plant-environment interactions. However, current understanding of the mechanistic controls on δ(18)O(L) does not provide complete characterization of effective path length (L) of the Péclet effect,--a key component of the leaf water model. In this study, we collected diurnal and seasonal series of leaf water enrichment and estimated L in six field-grown angiosperm and gymnosperm tree species. Our results suggest a pivotal role of leaf transpiration rate (E) in driving both within- and across-species variations in L. Our observation of the common presence of an inverse scaling of L with E in the different species therefore cautions against (1) the conventional treatment of L as a species-specific constant in leaf water or cellulose isotope (δ(18)O(p)) modelling; and (2) the use of δ(18)O(p) as a proxy for gs or E under low E conditions. Further, we show that incorporation of a multi-species L-E scaling into the leaf water model has the potential to both improve the prediction accuracy and simplify parameterization of the model when compared with the conventional approach. This has important implications for future modelling of oxygen isotope ratios.
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Affiliation(s)
- Xin Song
- Department of Biology, University of Pennsylvania, 433 S University Ave., Philadelphia, PA 19104, USA.
| | - Margaret M Barbour
- Landcare Research, PO Box 40, Lincoln, 7640, New Zealand
- Faculty of Agriculture and Environment, University of Sydney, Private Bag 4110, Narellan, NSW, 2567, Australia
| | - Graham D Farquhar
- Research School of Biology, The Australian National University, Canberra, ACT, 0200, Australia
| | - David R Vann
- Department of Biology, University of Pennsylvania, 433 S. University Ave., Philadelphia, PA, 19104, USA
| | - Brent R Helliker
- Department of Biology, University of Pennsylvania, 433 S. University Ave., Philadelphia, PA, 19104, USA
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44
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Cernusak LA, Kahmen A. The multifaceted relationship between leaf water (18)O enrichment and transpiration rate. PLANT, CELL & ENVIRONMENT 2013; 36:1239-1241. [PMID: 23421713 DOI: 10.1111/pce.12081] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 02/12/2013] [Indexed: 06/01/2023]
Affiliation(s)
- Lucas A Cernusak
- Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia.
| | - Ansgar Kahmen
- Institute of Agricultural Sciences, ETH Zurich, Zurich, 8092, Switzerland
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45
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Abstract
Leaf-wax n-alkanes (2)H/(1)H ratios are widely used as a proxy in climate reconstruction. Although the broad nature of the relationship between n-alkanes δ(2)H values and climate is appreciated, the quantitative details of the proxy remain elusive. To examine these details under natural environmental conditions, we studied a riparian broadleaf angiosperm species, Populus angustifolia, growing on water with a constant δ(2)H value and monitored the δ(2)H values of leaf-wax n-alkanes and of stem, leaf, stream, and atmospheric waters throughout the entire growing season. Here we found the δ(2)H values of leaf-wax n-alkanes recorded only a 2-wk period during leaf flush and did not vary for the 19 weeks thereafter when leaves remained active. We found δ(2)H values of leaf-wax n-alkanes of P. angustifolia record conditions earlier in the season rather than fully integrating the entire growing season. Using these data, we modeled precipitation δ(2)H values during the time of wax synthesis. We observed that the isotope ratios of this precipitation generally were (2)H-enriched compared with mean annual precipitation. This model provides a mechanistic basis of the often-observed (2)H-enrichment from the expected fractionation values in studies of broadleaf angiosperm leaf-wax δ(2)H. In addition, these findings may have implications for the spatial and temporal uses of n-alkane δ(2)H values in paleoapplications; when both plant community and growth form are known, this study allows the isolation of the precipitation dynamics of individual periods of the growing season.
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Ellsworth PV, Ellsworth PZ, Anderson WT, Sternberg LSL. The role of effective leaf mixing length in the relationship between the δ18 O of stem cellulose and source water across a salinity gradient. PLANT, CELL & ENVIRONMENT 2013; 36:138-148. [PMID: 22716972 DOI: 10.1111/j.1365-3040.2012.02562.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Previous mangrove tree ring studies attempted, unsuccessfully, to relate the δ(18) O of trunk cellulose (δ(18) O(CELL) ) to the δ(18) O of source water (δ(18) O(SW) ). Here, we tested whether biochemical fractionation associated with one of the oxygen in the cellulose glucose moiety or variation in leaf water oxygen isotope fractionation (Δ(LW) ) can interfere with the δ(18) O(SW) signal as it is recorded in the δ(18) O(CELL) of mangrove (saltwater) and hammock (freshwater) plants. We selected two transects experiencing a salinity gradient, located in the Florida Keys, USA. The δ(18) O(CELL) throughout both transects did not show the pattern expected based on that of the δ(18) O(SW) . We found that in one of the transects, biochemical fractionation interfered with the δ(18) O(SW) signal, while in the other transect Δ(LW) differed between mangrove and hammock plants. Observed differences in Δ(LW) between mangroves and hammocks were caused by a longer effective leaf mixing length (L) of the water pathway in mangrove leaves compared to those of hammock leaves. Changes in L could have caused the δ(18) O(CELL) to record not only variations in the δ(18) O(SW) but also in Δ(LW) making it impossible to isolate the δ(18) O(SW) signal.
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Moreno-Gutiérrez C, Dawson TE, Nicolás E, Querejeta JI. Isotopes reveal contrasting water use strategies among coexisting plant species in a Mediterranean ecosystem. THE NEW PHYTOLOGIST 2012; 196:489-496. [PMID: 22913668 DOI: 10.1111/j.1469-8137.2012.04276.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 07/09/2012] [Indexed: 05/20/2023]
Abstract
Variation in the stable carbon and oxygen isotope composition (δ13C, Δ18O) of co-occurring plant species may reflect the functional diversity of water use strategies present in natural plant communities. We investigated the patterns of water use among 10 coexisting plant species representing diverse taxonomic groups and life forms in semiarid southeast Spain by measuring their leaf δ13C and Δ18O, the oxygen isotope ratio of stem water and leaf gas exchange rates. Across species, Δ18O was tightly negatively correlated with stomatal conductance (gs), whereas δ13C was positively correlated with intrinsic water use efficiency (WUEi). Broad interspecific variation in Δ18O, δ13C and WUEi was largely determined by differences in gs, as indicated by a strong positive correlation between leaf δ13C and Δ18O across species The 10 co-occurring species segregated along a continuous ecophysiological gradient defined by their leaf δ13C and Δ18O, thus revealing a wide spectrum of stomatal regulation intensity and contrasting water use strategies ranging from 'profligate/opportunistic' (high gs, low WUEi) to 'conservative' (low gs, high WUEi). Coexisting species maintained their relative isotopic rankings in 2 yr with contrasting rainfall, suggesting the existence of species-specific 'isotopic niches' that reflect ecophysiological niche segregation in dryland plant communities.
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Affiliation(s)
- Cristina Moreno-Gutiérrez
- Centro de Edafología y Biología Aplicada del Segura (CEBAS-CSIC), Campus Universitario de Espinardo, PO Box 164, 30100, Murcia, Spain
| | - Todd E Dawson
- Center for Stable Isotope Biogeochemistry and the Department of Integrative Biology, University of California, Berkeley, CA, 94720, USA
| | - Emilio Nicolás
- Centro de Edafología y Biología Aplicada del Segura (CEBAS-CSIC), Campus Universitario de Espinardo, PO Box 164, 30100, Murcia, Spain
| | - José Ignacio Querejeta
- Centro de Edafología y Biología Aplicada del Segura (CEBAS-CSIC), Campus Universitario de Espinardo, PO Box 164, 30100, Murcia, Spain
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48
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Ferrio JP, Pou A, Florez-Sarasa I, Gessler A, Kodama N, Flexas J, Ribas-Carbó M. The Péclet effect on leaf water enrichment correlates with leaf hydraulic conductance and mesophyll conductance for CO(2). PLANT, CELL & ENVIRONMENT 2012; 35:611-625. [PMID: 21988489 DOI: 10.1111/j.1365-3040.2011.02440.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Leaf water gets isotopically enriched through transpiration, and diffusion of enriched water through the leaf depends on transpiration flow and the effective path length (L). The aim of this work was to relate L with physiological variables likely to respond to similar processes. We studied the response to drought and vein severing of leaf lamina hydraulic conductance (K(lamina) ), mesophyll conductance for CO(2) (g(m) ) and leaf water isotope enrichment in Vitis vinifera L cv. Grenache. We hypothesized that restrictions in water pathways would reduce K(lamina) and increase L. As a secondary hypothesis, we proposed that, given the common pathways for water and CO(2) involved, a similar response should be found in g(m) . Our results showed that L was strongly related to mesophyll variables, such as K(lamina) or g(m) across experimental drought and vein-cutting treatments, showing stronger relationships than with variables included as input parameters for the models, such as transpiration. Our findings were further supported by a literature survey showing a close link between L and leaf hydraulic conductance (K(leaf) = 31.5 × L(-0.43) , r(2) = 0.60, n = 24). The strong correlation found between L, K(lamina) and g(m) supports the idea that water and CO(2) share an important part of their diffusion pathways through the mesophyll.
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Affiliation(s)
- Juan Pedro Ferrio
- Department of Crop and Forest Science, Universitat de Lleida, Lleida, Spain
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49
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Kahmen A, Dawson TE, Vieth A, Sachse D. Leaf wax n-alkane δD values are determined early in the ontogeny of Populus trichocarpa leaves when grown under controlled environmental conditions. PLANT, CELL & ENVIRONMENT 2011; 34:1639-1651. [PMID: 21696403 DOI: 10.1111/j.1365-3040.2011.02360.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The stable hydrogen isotope ratios (δD) of leaf wax n-alkanes record valuable information on plant and ecosystem water relations. It remains, however, unknown if leaf wax n-alkane δD values record only environmental variation during the brief period of time of leaf growth or if leaf wax n-alkane δD values are affected by environmental variability throughout the entire lifespan of a leaf. To resolve these uncertainties, we irrigated Populus trichocarpa trees with a pulse of deuterium-enriched water and used compound-specific stable hydrogen isotope analyses to test if the applied tracer could be recovered from leaf wax n-alkanes of leaves that were at different stages of their development during the tracer application. Our experiment revealed that only leaf wax n-alkanes from leaves that had developed during the time of the tracer application were affected, while leaves that were already fully matured at the time of the tracer application were not. We conclude from our study that under controlled environmental conditions, leaf wax n-alkanes are synthesized only early in the ontogeny of a leaf. Our experiment has implications for the interpretation of leaf wax n-alkane δD values in an environmental context, as it suggests that these compounds record only a brief period of the environmental variability that a leaf experiences throughout its life.
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Affiliation(s)
- Ansgar Kahmen
- Center for Stable Isotope Biogeochemistry, Department of Integrative Biology, University of California, Berkeley, CA, USA.
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Helliker BR. On the controls of leaf-water oxygen isotope ratios in the atmospheric Crassulacean acid metabolism epiphyte Tillandsia usneoides. PLANT PHYSIOLOGY 2011; 155:2096-107. [PMID: 21300917 PMCID: PMC3091089 DOI: 10.1104/pp.111.172494] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Accepted: 02/06/2011] [Indexed: 05/14/2023]
Abstract
Previous theoretical work showed that leaf-water isotope ratio (δ(18)O(L)) of Crassulacean acid metabolism epiphytes was controlled by the δ(18)O of atmospheric water vapor (δ(18)O(a)), and observed δ(18)O(L) could be explained by both a non-steady-state model and a "maximum enrichment" steady-state model (δ(18)O(L-M)), the latter requiring only δ(18)O(a) and relative humidity (h) as inputs. δ(18)O(L), therefore, should contain an extractable record of δ(18)O(a). Previous empirical work supported this hypothesis but raised many questions. How does changing δ(18)O(a) and h affect δ(18)O(L)? Do hygroscopic trichomes affect observed δ(18)O(L)? Are observations of changes in water content required for the prediction of δ(18)O(L)? Does the leaf need to be at full isotopic steady state for observed δ(18)O(L) to equal δ(18)O(L-M)? These questions were examined with a climate-controlled experimental system capable of holding δ(18)O(a) constant for several weeks. Water adsorbed to trichomes required a correction ranging from 0.5‰ to 1‰. δ(18)O(L) could be predicted using constant values of water content and even total conductance. Tissue rehydration caused a transitory change in δ(18)O(L), but the consequent increase in total conductance led to a tighter coupling with δ(18)O(a). The non-steady-state leaf water models explained observed δ(18)O(L) (y = 0.93*x - 0.07; r(2) = 0.98) over a wide range of δ(18)O(a) and h. Predictions of δ(18)O(L-M) agreed with observations of δ(18)O(L) (y = 0.87*x - 0.99; r(2) = 0.92), and when h > 0.9, the leaf did not need to be at isotopic steady state for the δ(18)O(L-M) model to predict δ(18)O(L) in the Crassulacean acid metabolism epiphyte Tillandsia usneoides.
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Affiliation(s)
- Brent R Helliker
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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