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Salomón RL, Helm J, Gessler A, Grams TEE, Hilman B, Muhr J, Steppe K, Wittmann C, Hartmann H. The quandary of sources and sinks of CO2 efflux in tree stems-new insights and future directions. TREE PHYSIOLOGY 2024; 44:tpad157. [PMID: 38214910 DOI: 10.1093/treephys/tpad157] [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: 09/15/2023] [Accepted: 12/12/2023] [Indexed: 01/13/2024]
Abstract
Stem respiration (RS) substantially contributes to the return of photo assimilated carbon to the atmosphere and, thus, to the tree and ecosystem carbon balance. Stem CO2 efflux (ECO2) is often used as a proxy for RS. However, this metric has often been challenged because of the uncertain origin of CO2 emitted from the stem due to post-respiratory processes. In this Insight, we (i) describe processes affecting the quantification of RS, (ii) review common methodological approaches to quantify and model RS and (iii) develop a research agenda to fill the most relevant knowledge gaps that we identified. Dissolution, transport and accumulation of respired CO2 away from its production site, reassimilation of respired CO2 via stem photosynthesis and the enzyme phosphoenolpyruvate carboxylase, axial CO2 diffusion in the gas phase, shifts in the respiratory substrate and non-respiratory oxygen (O2) consumption are the most relevant processes causing divergence between RS and measured stem gas exchange (ECO2 or O2 influx, IO2). Two common methodological approaches to estimate RS, namely the CO2 mass balance approach and the O2 consumption technique, circumvent some of these processes but have yielded inconsistent results regarding the fate of respired CO2. Stem respiration modelling has recently progressed at the organ and tree levels. However, its implementation in large-scale models, commonly operated from a source-driven perspective, is unlikely to reflect adequate mechanisms. Finally, we propose hypotheses and approaches to advance the knowledge of the stem carbon balance, the role of sap pH on RS, the reassimilation of respired CO2, RS upscaling procedures, large-scale RS modelling and shifts in respiratory metabolism during environmental stress.
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Affiliation(s)
- Roberto L Salomón
- Universidad Politécnica de Madrid (UPM), Departamento de Sistemas y Recursos Naturales, Research Group FORESCENT, Antonio Novais 10, 28040, Madrid, Spain
- Department of Plants and Crops, Laboratory of Plant Ecology, Ghent University, Faculty of Bioscience Engineering, Coupure Links 653, 9000 Ghent, Belgium
| | - Juliane Helm
- Max-Planck-Institute for Biogeochemistry, Biogeochemical Processes, Hans-Knöll-Str. 10, 07743 Jena, Germany
- Department of Environmental Sciences - Botany, Basel University, Schönbeinstr. 6, Basel CH-4056, Switzerland
| | - Arthur Gessler
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zurcherstrasse 111, 8903 Birmensdorf, Switzerland
- Institute of Terrestrial Ecosystems, ETH Zürich, Rämistrasse 101, 8902 Zurich, Switzerland
| | - Thorsten E E Grams
- Technical University of Munich, Ecophysiology of Plants, Land Surface - Atmosphere Interactions, Von-Carlowitz-Platz 2, 85354 Freising, Germany
| | - Boaz Hilman
- Max-Planck-Institute for Biogeochemistry, Biogeochemical Processes, Hans-Knöll-Str. 10, 07743 Jena, Germany
| | - Jan Muhr
- Department of Forest Botany and Tree Physiology, Laboratory for Radioisotopes, Georg-August Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany
| | - Kathy Steppe
- Department of Plants and Crops, Laboratory of Plant Ecology, Ghent University, Faculty of Bioscience Engineering, Coupure Links 653, 9000 Ghent, Belgium
| | - Christiane Wittmann
- Faculty of Biology, Botanical Garden, University of Duisburg-Essen, Universitätsstrasse 5, 45117 Essen, Germany
| | - Henrik Hartmann
- Max-Planck-Institute for Biogeochemistry, Biogeochemical Processes, Hans-Knöll-Str. 10, 07743 Jena, Germany
- Institute for Forest Protection, Julius Kühn Institute Federal Research Centre for Cultivated Plants, Erwin-Baur-Straße 27, 06484 Quedlinburg, Germany
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Darenova E, Knott R, Vichta T. Does lower water availability limit stem CO 2 efflux of oak and hornbeam coppices? AOB PLANTS 2024; 16:plae023. [PMID: 38638333 PMCID: PMC11025467 DOI: 10.1093/aobpla/plae023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 04/04/2024] [Indexed: 04/20/2024]
Abstract
Recent changes in water availability can be crucial for the development, growth and carbon budget of forests. Therefore, our aim was to determine the effect of reduced throughfall and severe summer drought on stem CO2 efflux as a function of temperature and stem increment. Stem CO2 efflux was measured using the chamber method on oak and hornbeam under four treatments: coppice, thinned coppice, and both coppice and thinned coppice with 30 %-reduced throughfall. The first year of the experiment had favourable soil water availability and the second year was characterized by a dry summer. While reduced throughfall had no effect on stem CO2 efflux, the summer drought decreased efflux by 43-81 % during July and August. The stem CO2 efflux was reduced less severely (by 13-40 %) in September when the drought persisted but the stem increment was already negligible. The stem increment was also strongly affected by the drought, which was reflected in its paired relationship with stem CO2 efflux over the two experimental years. The study showed that summer dry periods significantly and rapidly reduce stem CO2 efflux, whereas a constant 30 % rainfall reduction needs probably a longer time to affect stem properties, and indirectly stem CO2 efflux.
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Affiliation(s)
- Eva Darenova
- Global Change Research Institute of the Czech Academy of Sciences, Belidla 986/4a, 60300 Brno, Czech Republic
- Department of Forest Ecology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 1665/1, Brno 613 00, Czech Republic
| | - Robert Knott
- Department of Silviculture, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 1665/1, Brno 613 00, Czech Republic
| | - Tomáš Vichta
- Department of Geology and Soil Science, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemedelska 1665/1, Brno 613 00, Czech Republic
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Tarvainen L, Henriksson N, Näsholm T, Marshall JD. Among-species variation in sap pH affects the xylem CO 2 transport potential in trees. THE NEW PHYTOLOGIST 2023; 238:926-931. [PMID: 36683449 DOI: 10.1111/nph.18768] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 12/26/2022] [Indexed: 06/17/2023]
Affiliation(s)
- Lasse Tarvainen
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 461, Gothenburg, SE-405 30, Sweden
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Skogmarksgränd, SE-901 83, Umeå, Sweden
| | - Nils Henriksson
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Skogmarksgränd, SE-901 83, Umeå, Sweden
| | - Torgny Näsholm
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Skogmarksgränd, SE-901 83, Umeå, Sweden
| | - John D Marshall
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Skogmarksgränd, SE-901 83, Umeå, Sweden
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Jardine K, Augusto E, Levine SD, Sunder A, Som S, Chambers J. Development of a lightweight, portable, waterproof, and low power stem respiration system for trees. MethodsX 2022; 10:101986. [PMID: 36654532 PMCID: PMC9841172 DOI: 10.1016/j.mex.2022.101986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 12/26/2022] [Indexed: 12/30/2022] Open
Abstract
Stem respiration is a quantitatively important, but poorly understood component of ecosystem carbon cycling in terrestrial ecosystems. However, a dynamic stem gas exchange system for quantifying real-time stem carbon dioxide (CO2) efflux (Es) is not commercially available resulting in limited observations based on the static method where air is recirculated through a stem enclosure. The static method has limited temporal resolution, suffers from condensation issues, requires a leak-free enclosure, which is often difficult to verify in the field, and requires physically removing the chamber or flushing it with ambient air before starting each measurement.•With the goal of improving our quantitative understanding of biophysical, physiological, biochemical, and environmental factors that influence diurnal Es patterns, here we present a custom system for quantifying real-time stem Es in remote tropical forests.•The system is low cost, lightweight, and waterproof with low power requirements (1.2-2.4 W) for real-time monitoring of stem Es using a 3D printed dynamic stem chamber and a 12V car battery. The design offers control over the flow rate through the stem chamber, eliminates the need for a pump to introduce air into the chamber, and water condensation issues by removing water vapor prior to CO2 analysis.•Following a simple CO2 infrared gas analyzer (IRGA) calibration and match procedure with a 400-ppm standard, we quantified diurnal Es observations over a 24-hours period during the summer growing season from an ash tree (Fraxinus sp.) in Fort Collins, Colorado. The results are consistent with previous laboratory and field studies that show Es can be suppressed during the day relative to the night.
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Affiliation(s)
- Kolby Jardine
- Climate and Ecosystem Sciences Division, Department of Ecology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
- Laboratório de Manejo Florestal, Instituto Nacional de Pesquisas na Amazônia - INPA, Manaus, AM 69.067-375, Brazil
- Corresponding author.
| | - Edson Augusto
- Laboratório de Manejo Florestal, Instituto Nacional de Pesquisas na Amazônia - INPA, Manaus, AM 69.067-375, Brazil
| | - Sienna D. Levine
- Energy systems, University of California Davis, Shields Ave, Davis, CA 95616, United States
| | - Aatish Sunder
- Climate and Ecosystem Sciences Division, Department of Ecology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
| | - Suman Som
- Climate and Ecosystem Sciences Division, Department of Ecology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
| | - Jeffrey Chambers
- Climate and Ecosystem Sciences Division, Department of Ecology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
- Laboratório de Manejo Florestal, Instituto Nacional de Pesquisas na Amazônia - INPA, Manaus, AM 69.067-375, Brazil
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Oren I, Mannerheim N, Fangmeier A, Buchmann N, Grünzweig JM. Patterns of total root and shoot carbon dioxide fluxes and their impact on daily tree carbon budget in large tropical tree saplings. TREE PHYSIOLOGY 2022; 42:958-970. [PMID: 34940886 DOI: 10.1093/treephys/tpab169] [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: 04/29/2021] [Accepted: 12/13/2021] [Indexed: 06/14/2023]
Abstract
A significant amount of the carbon (C) assimilated in photosynthesis by trees is re-emitted to the atmosphere via the respiratory CO2 flux of roots. Because of technical constraints, we have little understanding of the extent and dynamics of the respiratory CO2 flux of roots at the total root system scale (RCF). This study aimed to fill this gap and to quantify the daily C budget of entire trees. We used aeroponics as a novel approach to measure directly and simultaneously RCF and the net CO2 flux of the entire shoot (SCF), to estimate their night- and day-time contributions to daily tree CO2 budget and to estimate the relative contribution of different root categories to RCF in large saplings of the tropical tree species Ceiba pentandra (L.) Gaertn. By maintaining root temperature within a narrow range (24-27.5 °C), we controlled for its effect on RCF, thus allowing the potential relationship between RCF and SCF to be tested. The carbon gain of the fast-growing saplings was 0.79 ± 0.10 g C sapling-1 day-1, with day-time shoot CO2 uptake outweighing night-time shoot and day- and night-time root CO2 losses by a factor of two. Other than a slight rise in the morning hours, RCF was relatively stable and not coupled to the daily dynamics of SCF. Albeit having lower specific respiration rates compared with fine-roots, the relative contributions of coarse-roots (diameter >2 mm) to RCF were substantial because of their large biomass and were estimated to range from 43 to 63% of RCF at midday of different days during the growing season. The results of this study suggest that (i) the entire root system needs to be monitored for its impact on the tree CO2 budget, (ii) RCF cannot be derived from SCF and (iii) the importance of coarse-root respiration to RCF may be greater than appreciated.
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Affiliation(s)
- Israel Oren
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Herzl Street POB 12, Rehovot 7610001, Israel
- Current affiliation: Université catholique de Louvain, Earth and Life Institute, Croix du Sud 2-11, 1348 Louvain-la-Neuve, Belgium
| | - Neringa Mannerheim
- Institute of Agricultural Sciences, ETH Zürich, Universitätstrasse 2, Zürich 8092, Switzerland
| | - Andreas Fangmeier
- Institute of Landscape and Plant Ecology, University of Hohenheim, August-von-Hartmann-Str. 3, Stuttgart 70599, Germany
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH Zürich, Universitätstrasse 2, Zürich 8092, Switzerland
| | - José M Grünzweig
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Herzl Street POB 12, Rehovot 7610001, Israel
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Salomón RL, De Roo L, Oleksyn J, Steppe K. Mechanistic drivers of stem respiration: A modelling exercise across species and seasons. PLANT, CELL & ENVIRONMENT 2022; 45:1270-1285. [PMID: 34914118 DOI: 10.1111/pce.14246] [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: 08/03/2021] [Revised: 09/22/2021] [Accepted: 12/03/2021] [Indexed: 06/14/2023]
Abstract
Stem respiration (RS ) plays a crucial role in plant carbon budgets. However, its poor understanding limits our ability to model woody tissue and whole-tree respiration. A biophysical model of stem water and carbon fluxes (TReSpire) was calibrated on cedar, maple and oak trees during spring and late summer. For this, stem sap flow, water potential, diameter variation, temperature, CO2 efflux, allometry and biochemistry were monitored. Shoot photosynthesis (PN ) and nonstructural carbohydrates (NSC) were additionally measured to evaluate source-sink relations. The highest RS and stem growth was found in maple and oak during spring, both being seasonally decoupled from PN and [NSC]. Temperature largely affected maintenance respiration (RM ) in the short term, but temperature-normalized RM was highly variable on a seasonal timescale. Overall, most of the respired CO2 radially diffused to the atmosphere (>87%) while the remainder was transported upward with the transpiration stream. The modelling exercise highlights the sink-driven behaviour of RS and the significance of overall metabolic activity on nitrogen (N) allocation patterns and N-normalized respiratory costs to capture RS variability over the long term. These insights should be considered when modelling plant respiration, whose representation is currently biased towards a better understanding of leaf metabolism.
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Affiliation(s)
- Roberto L Salomón
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
- Sistemas Naturales e Historia Forestal, Universidad Politécnica de Madrid, Madrid, Spain
| | - Linus De Roo
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Jacek Oleksyn
- Polish Academy of Sciences, Institute of Dendrology, Körnik, Poland
| | - Kathy Steppe
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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7
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Lintunen A, Preisler Y, Oz I, Yakir D, Vesala T, Hölttä T. Bark Transpiration Rates Can Reach Needle Transpiration Rates Under Dry Conditions in a Semi-arid Forest. FRONTIERS IN PLANT SCIENCE 2021; 12:790684. [PMID: 34987535 PMCID: PMC8721219 DOI: 10.3389/fpls.2021.790684] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 11/17/2021] [Indexed: 05/25/2023]
Abstract
Drought can cause tree mortality through hydraulic failure and carbon starvation. To prevent excess water loss, plants typically close their stomata before massive embolism formation occurs. However, unregulated water loss through leaf cuticles and bark continues after stomatal closure. Here, we studied the diurnal and seasonal dynamics of bark transpiration and how it is affected by tree water availability. We measured continuously for six months water loss and CO2 efflux from branch segments and needle-bearing shoots in Pinus halepensis growing in a control and an irrigation plot in a semi-arid forest in Israel. Our aim was to find out how much passive bark transpiration is affected by tree water status in comparison with shoot transpiration and bark CO2 emission that involve active plant processes, and what is the role of bark transpiration in total tree water use during dry summer conditions. Maximum daily water loss rate per bark area was 0.03-0.14 mmol m-2 s-1, which was typically ~76% of the shoot transpiration rate (on leaf area basis) but could even surpass the shoot transpiration rate during the highest evaporative demand in the control plot. Irrigation did not affect bark transpiration rate. Bark transpiration was estimated to account for 64-78% of total water loss in drought-stressed trees, but only for 6-11% of the irrigated trees, due to differences in stomatal control between the treatments. Water uptake through bark was observed during most nights, but it was not high enough to replenish the lost water during the day. Unlike bark transpiration, branch CO2 efflux decreased during drought due to decreased metabolic activity. Our results demonstrate that although bark transpiration represents a small fraction of the total water loss through transpiration from foliage in non-stressed trees, it may have a large impact during drought.
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Affiliation(s)
- Anna Lintunen
- Institute for Atmospheric and Earth System Research/Physics, University of Helsinki, Helsinki, Finland
- Institute for Atmospheric and Earth System Research/Forest Sciences, University of Helsinki, Helsinki, Finland
| | - Yakir Preisler
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot,Israel
| | - Itay Oz
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot,Israel
| | - Dan Yakir
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot,Israel
| | - Timo Vesala
- Institute for Atmospheric and Earth System Research/Physics, University of Helsinki, Helsinki, Finland
- Institute for Atmospheric and Earth System Research/Forest Sciences, University of Helsinki, Helsinki, Finland
- Laboratory of Ecosystem-Atmospheric Interactions of Forest - Mire Complexes, Yugra State University, Khanty-Mansiysk, Russia
| | - Teemu Hölttä
- Institute for Atmospheric and Earth System Research/Forest Sciences, University of Helsinki, Helsinki, Finland
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Salomón RL, De Roo L, Bodé S, Boeckx P, Steppe K. Efflux and assimilation of xylem-transported CO 2 in stems and leaves of tree species with different wood anatomy. PLANT, CELL & ENVIRONMENT 2021; 44:3494-3508. [PMID: 33822389 DOI: 10.1111/pce.14062] [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: 01/13/2021] [Revised: 03/30/2021] [Accepted: 03/31/2021] [Indexed: 06/12/2023]
Abstract
Determining the fate of CO2 respired in woody tissues is necessary to understand plant respiratory physiology and to evaluate CO2 recycling mechanisms. An aqueous 13 C-enriched CO2 solution was infused into the stem of 3-4 m tall trees to estimate efflux and assimilation of xylem-transported CO2 via cavity ring-down laser spectroscopy and isotope ratio mass spectrometry, respectively. Different tree locations (lower stem, upper stem and leafy shoots) and tissues (xylem, bark and leaves) were monitored in species with tracheid, diffuse- and ring-porous wood anatomy (cedar, maple and oak, respectively). Radial xylem CO2 diffusivity and xylem [CO2 ] were lower in cedar relative to maple and oak trees, thereby limiting label diffusion. Part of the labeled 13 CO2 was assimilated in cedar (8.7%) and oak (20.6%) trees, mostly in xylem and bark tissues of the stem, while limited solution uptake in maple trees hindered the detection of label assimilation. Little label reached foliar tissues, suggesting substantial label loss along the stem-branch transition following reductions in the radial diffusive pathway. Differences in respiration rates and radial xylem CO2 diffusivity (lower in conifer relative to angiosperm species) might reconcile discrepancies in efflux and assimilation of xylem-transported CO2 so far observed between taxonomic clades.
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Affiliation(s)
- Roberto Luis Salomón
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
- Grupo de Investigación Sistemas Naturales e Historia Forestal, Universidad Politécnica de Madrid, Madrid, Spain
| | - Linus De Roo
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Samuel Bodé
- Isotope Bioscience Laboratory-ISOFYS, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Pascal Boeckx
- Isotope Bioscience Laboratory-ISOFYS, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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Lauriks F, Salomón RL, De Roo L, Steppe K. Leaf and tree responses of young European aspen trees to elevated atmospheric CO2 concentration vary over the season. TREE PHYSIOLOGY 2021; 41:1877-1892. [PMID: 33824983 DOI: 10.1093/treephys/tpab048] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 03/31/2021] [Indexed: 06/12/2023]
Abstract
Elevated atmospheric CO2 concentration (eCO2) commonly stimulates net leaf assimilation, decreases stomatal conductance and has no clear effect on leaf respiration. However, effects of eCO2 on whole-tree functioning and its seasonal dynamics remain far more uncertain. To evaluate temporal and spatial variability in eCO2 effects, 1-year-old European aspen trees were grown in two treatment chambers under ambient (aCO2, 400 p.p.m.) and elevated (eCO2, 700 p.p.m.) CO2 concentrations during an early (spring 2019) and late (autumn 2018) seasonal experiment. Leaf (net carbon assimilation, stomatal conductance and leaf respiration) and whole-tree (stem growth, sap flow and stem CO2 efflux) responses to eCO2 were measured. Under eCO2, carbon assimilation was stimulated during the early (1.63-fold) and late (1.26-fold) seasonal experiments. Stimulation of carbon assimilation changed over time with largest increases observed in spring when stem volumetric growth was highest, followed by late season down-regulation, when stem volumetric growth ceased. The neutral eCO2 effect on stomatal conductance and leaf respiration measured at leaf level paralleled the unresponsive canopy conductance (derived from sap flow measurements) and stem CO2 efflux measured at tree level. Our results highlight that seasonality in carbon demand for tree growth substantially affects the magnitude of the response to eCO2 at both leaf and whole-tree level.
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Affiliation(s)
- Fran Lauriks
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium
| | - Roberto Luis Salomón
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium
- Grupo de Investigación Sistemas Naturales e Historia Forestal, Universidad Politécnica de Madrid, Madrid 28040, Spain
| | - Linus De Roo
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium
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Tarvainen L, Wallin G, Linder S, Näsholm T, Oren R, Ottosson Löfvenius M, Räntfors M, Tor-Ngern P, Marshall JD. Limited vertical CO2 transport in stems of mature boreal Pinus sylvestris trees. TREE PHYSIOLOGY 2021; 41:63-75. [PMID: 32864696 DOI: 10.1093/treephys/tpaa113] [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: 01/21/2020] [Accepted: 08/25/2020] [Indexed: 05/14/2023]
Abstract
Several studies have suggested that CO2 transport in the transpiration stream can considerably bias estimates of root and stem respiration in ring-porous and diffuse-porous tree species. Whether this also happens in species with tracheid xylem anatomy and lower sap flow rates, such as conifers, is currently unclear. We infused 13C-labelled solution into the xylem near the base of two 90-year-old Pinus sylvestris L. trees. A custom-built gas exchange system and an online isotopic analyser were used to sample the CO2 efflux and its isotopic composition continuously from four positions along the bole and one upper canopy shoot in each tree. Phloem and needle tissue 13C enrichment was also evaluated at these positions. Most of the 13C label was lost by diffusion within a few metres of the infusion point indicating rapid CO2 loss during vertical xylem transport. No 13C enrichment was detected in the upper bole needle tissues. Furthermore, mass balance calculations showed that c. 97% of the locally respired CO2 diffused radially to the atmosphere. Our results support the notion that xylem CO2 transport is of limited magnitude in conifers. This implies that the concerns that stem transport of CO2 derived from root respiration biases chamber-based estimates of forest carbon cycling may be unwarranted for mature conifer stands.
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Affiliation(s)
- Lasse Tarvainen
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Skogmarksgränd, SE-901 83 Umeå, Sweden
- Department of Biological and Environmental Sciences, University of Gothenburg, Carl Skottsbergs gata 22B, SE-405 30 Gothenburg, Sweden
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Linnaeus väg 6, SE-901 87 Umeå, Sweden
| | - Göran Wallin
- Department of Biological and Environmental Sciences, University of Gothenburg, Carl Skottsbergs gata 22B, SE-405 30 Gothenburg, Sweden
| | - Sune Linder
- Southern Swedish Forest Research Centre, SLU, PO Box 49, SE-230 53, Alnarp, Sweden
| | - Torgny Näsholm
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Skogmarksgränd, SE-901 83 Umeå, Sweden
| | - Ram Oren
- Nicholas School of the Environment, Duke University, Grainger Hall, 9 Circuit Drive, Box 90328, Durham, NC 27708-0328, USA
- Pratt School of Engineering, Duke University, 305 Teer Building, Box 90271, Durham, NC 27708-0271, USA
- Department of Forest Sciences, University of Helsinki, Latokartanonkaari 7, Box 27, FI-00014 Helsinki, Finland
| | - Mikaell Ottosson Löfvenius
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Skogmarksgränd, SE-901 83 Umeå, Sweden
| | - Mats Räntfors
- Department of Biological and Environmental Sciences, University of Gothenburg, Carl Skottsbergs gata 22B, SE-405 30 Gothenburg, Sweden
| | - Pantana Tor-Ngern
- Department of Environmental Science, Faculty of Science, Chulalongkorn University, 254 Phayathai Rd, Wang Mai, Pathum Wan District, 10330 Bangkok, Thailand
- Environment, Health and Social Data Analytics Research Group, Chulalongkorn University, 254 Phayathai Rd, Wang Mai, Pathum Wan District, 10330 Bangkok, Thailand
| | - John D Marshall
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Skogmarksgränd, SE-901 83 Umeå, Sweden
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D'Andrea E, Rezaie N, Prislan P, Gričar J, Collalti A, Muhr J, Matteucci G. Frost and drought: Effects of extreme weather events on stem carbon dynamics in a Mediterranean beech forest. PLANT, CELL & ENVIRONMENT 2020; 43:2365-2379. [PMID: 32705694 DOI: 10.1111/pce.13858] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 07/17/2020] [Accepted: 07/20/2020] [Indexed: 06/11/2023]
Abstract
The effects of short-term extreme events on tree functioning and physiology are still rather elusive. European beech is one of the most sensitive species to late frost and water shortage. We investigated the intra-annual C dynamics in stems under such conditions. Wood formation and stem CO2 efflux were monitored in a Mediterranean beech forest for 3 years (2015-2017), including a late frost (2016) and a summer drought (2017). The late frost reduced radial growth and, consequently, the amount of carbon fixed in the stem biomass by 80%. Stem carbon dioxide efflux in 2016 was reduced by 25%, which can be attributed to the reduction of effluxes due to growth respiration. Counter to our expectations, we found no effects of the 2017 summer drought on radial growth and stem carbon efflux. The studied extreme weather events had various effects on tree growth. Even though late spring frost had a strong impact on beech radial growth in the current year, trees fully recovered in the following growing season, indicating high resilience of beech to this stressful event.
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Affiliation(s)
- Ettore D'Andrea
- National Research Council of Italy, Institute for Agriculture and Forestry Systems in the Mediterranean (CNR-ISAFOM), Ercolano, Naples, Italy
| | - Negar Rezaie
- National Research Council of Italy, Institute for Agriculture and Forestry Systems in the Mediterranean (CNR-ISAFOM), Ercolano, Naples, Italy
- Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria, Centro Ricerca Ingegneria e Trasformazioni Agroalimentari (CREA-IT), Monterotondo Scalo, Rome, Italy
| | | | | | - Alessio Collalti
- National Research Council of Italy, Institute for Agriculture and Forestry Systems in the Mediterranean (CNR-ISAFOM), Perugia, Perugia, Italy
- Department of Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Jan Muhr
- Bioclimatology, University of Göttingen, Göttingen, Germany
- Department of Biogeochemical Processes, Max-Planck-Institute for Biogeochemistry, Jena, Germany
| | - Giorgio Matteucci
- National Research Council of Italy, Institute for Agriculture and Forestry Systems in the Mediterranean (CNR-ISAFOM), Ercolano, Naples, Italy
- Institute for BioEconomy (CNR-IBE), National Research Council of Italy, Sesto Fiorentino, Florence, Italy
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12
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Mincke J, Courtyn J, Vanhove C, Vandenberghe S, Steppe K. Studying in vivo dynamics of xylem-transported 11CO2 using positron emission tomography. TREE PHYSIOLOGY 2020; 40:1058-1070. [PMID: 32333788 DOI: 10.1093/treephys/tpaa048] [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: 12/10/2019] [Accepted: 04/20/2020] [Indexed: 05/26/2023]
Abstract
Respired CO2 in woody tissues can build up in the xylem and dissolve in the sap solution to be transported through the plant. From the sap, a fraction of the CO2 can either be radially diffuse to the atmosphere or be assimilated in chloroplasts present in woody tissues. These processes occur simultaneously in stems and branches, making it difficult to study their specific dynamics. Therefore, an 11C-enriched aqueous solution was administered to young branches of Populus tremula L., which were subsequently imaged by positron emission tomography (PET). This approach allows in vivo visualization of the internal movement of CO2 inside branches at high spatial and temporal resolution, and enables direct measurement of the transport speed of xylem-transported CO2 (vCO2). Through compartmental modeling of the dynamic data obtained from the PET images, we (i) quantified vCO2 and (ii) proposed a new method to assess the fate of xylem-transported 11CO2 within the branches. It was found that a fraction of 0.49 min-1 of CO2 present in the xylem was transported upwards. A fraction of 0.38 min-1 diffused radially from the sap to the surrounding parenchyma and apoplastic spaces (CO2,PA) to be assimilated by woody tissue photosynthesis. Another 0.12 min-1 of the xylem-transported CO2 diffused to the atmosphere via efflux. The remaining CO2 (i.e., 0.01 min-1) was stored as CO2,PA, representing the build-up within parenchyma and apoplastic spaces to be assimilated or directed to the atmosphere. Here, we demonstrate the outstanding potential of 11CO2-based plant-PET in combination with compartmental modeling to advance our understanding of internal CO2 movement and the respiratory physiology within woody tissues.
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Affiliation(s)
- Jens Mincke
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
- MEDISIP-INFINITY, Department of Electronics and Information Systems, Faculty of Engineering and Architecture, Ghent University, Corneel Heymanslaan 10, 9000 Ghent, Belgium
| | - Jan Courtyn
- Medical Molecular Imaging and Therapy, Department of Radiology and Nuclear Medicine, Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium
| | - Christian Vanhove
- MEDISIP-INFINITY, Department of Electronics and Information Systems, Faculty of Engineering and Architecture, Ghent University, Corneel Heymanslaan 10, 9000 Ghent, Belgium
| | - Stefaan Vandenberghe
- MEDISIP-INFINITY, Department of Electronics and Information Systems, Faculty of Engineering and Architecture, Ghent University, Corneel Heymanslaan 10, 9000 Ghent, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
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13
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De Roo L, Salomón RL, Steppe K. Woody tissue photosynthesis reduces stem CO 2 efflux by half and remains unaffected by drought stress in young Populus tremula trees. PLANT, CELL & ENVIRONMENT 2020; 43:981-991. [PMID: 31884680 DOI: 10.1111/pce.13711] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/19/2019] [Accepted: 12/21/2019] [Indexed: 06/10/2023]
Abstract
A substantial portion of locally respired CO2 in stems can be assimilated by chloroplast-containing tissues. Woody tissue photosynthesis (Pwt ) therefore plays a major role in the stem carbon balance. To study the impact of Pwt on stem carbon cycling along a gradient of water availability, stem CO2 efflux (EA ), xylem CO2 concentration ([CO2 ]), and xylem water potential (Ψxylem ) were measured in 4-year-old Populus tremula L. trees exposed to drought stress and different regimes of light exclusion of woody tissues. Under well-watered conditions, local Pwt decreased EA up to 30%. Axial CO2 diffusion (Dax ) induced by distant Pwt caused an additional decrease in EA of up to 25% and limited xylem [CO2 ] build-up. Under drought stress, absolute decreases in EA driven by Pwt remained stable, denoting that Pwt was not affected by drought. At the end of the dry period, when transpiration was low, local Pwt and Dax offset 20% and 10% of stem respiration on a daily basis, respectively. These results highlight (a) the importance of Pwt for an adequate interpretation of EA measurements and (b) homeostatic Pwt along a drought stress gradient, which might play a crucial role to fuel stem metabolism when leaf carbon uptake and phloem transport are limited.
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Affiliation(s)
- Linus De Roo
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Roberto Luis Salomón
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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14
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Marler TE, Lindström AJ. Diel patterns of stem CO 2 efflux vary among cycads, arborescent monocots, and woody eudicots and gymnosperms. PLANT SIGNALING & BEHAVIOR 2020; 15:1732661. [PMID: 32100615 PMCID: PMC7194385 DOI: 10.1080/15592324.2020.1732661] [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: 01/25/2020] [Revised: 02/13/2020] [Accepted: 02/15/2020] [Indexed: 05/28/2023]
Abstract
The diel patterns of stem carbon dioxide efflux (Es) were determined for cycads, monocots, and woody eudicot and gymnosperm tree species. Stem Es at a height of 30-40 cm was measured every 2 h throughout 31-h campaigns. Our range of Es was 1.5-4.0 µmol·m-2·s-1 for cycads, 1.0-3.5 µmol·m-2·s-1 for arborescent monocots, and 1.5-4.5 µmol·m-2·s-1 for woody eudicot and gymnosperm trees species. Time of day did not influence Es of cycads or monocots. In contrast, the woody stems of eudicots and gymnosperms exhibited diurnal Es that was 36% to 40% greater than nocturnal Es. The established literature based on Es of woody tree species cannot be used to estimate habitat carbon cycles in habitats which contain cycad or monocot trees. Time of day must be included for accuracy of research on Es of woody tree species. Failures to account for the spatiotemporal differences of Es may explain some of the disparity in outcomes of published stem respiration studies.
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Affiliation(s)
- Thomas E. Marler
- College of Natural and Applied Sciences, University of Guam, Mangilao, Guam, USA
| | - Anders J. Lindström
- Plant Collections Department, Nong Nooch Tropical Botanical Garden, Sattahip, Thailand
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15
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Salomón RL, De Roo L, Oleksyn J, De Pauw DJW, Steppe K. TReSpire - a biophysical TRee Stem respiration model. THE NEW PHYTOLOGIST 2020; 225:2214-2230. [PMID: 31494939 DOI: 10.1111/nph.16174] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 08/29/2019] [Indexed: 06/10/2023]
Abstract
Mechanistic models of plant respiration remain poorly developed, especially in stems and woody tissues where measurements of CO2 efflux do not necessarily reflect local respiratory activity. We built a process-based model of stem respiration that couples water and carbon fluxes at the organ level (TReSpire). To this end, sap flow, stem diameter variations, xylem and soil water potential, stem temperature, stem CO2 efflux and nonstructural carbohydrates were measured in a maple tree, while xylem CO2 concentration and additional stem and xylem diameter variations were monitored in an ancillary tree for model validation. TReSpire realistically described: (1) turgor pressure to differentiate growing from nongrowing metabolism; (2) maintenance expenditures in xylem and outer tissues based on Arrhenius kinetics and nitrogen content; and (3) radial CO2 diffusivity and CO2 solubility and transport in the sap solution. Collinearity issues with phloem unloading rates and sugar-starch interconversion rates suggest parallel submodelling to close the stem carbon balance. TReSpire brings a breakthrough in the modelling of stem water and carbon fluxes at a detailed (hourly) temporal resolution. TReSpire is calibrated from a sink-driven perspective, and has potential to advance our understanding on stem growth dynamics, CO2 fluxes and underlying respiratory physiology across different species and phenological stages.
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Affiliation(s)
- Roberto L Salomón
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent, 9000, Belgium
| | - Linus De Roo
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent, 9000, Belgium
| | - Jacek Oleksyn
- Polish Academy of Sciences, Institute of Dendrology, Parkowa 5, Kórnik, PL-62-035, Poland
| | - Dirk J W De Pauw
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent, 9000, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent, 9000, Belgium
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16
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Rodríguez-Calcerrada J, Salomón RL, Gordaliza GG, Miranda JC, Miranda E, de la Riva EG, Gil L. Respiratory costs of producing and maintaining stem biomass in eight co-occurring tree species. TREE PHYSIOLOGY 2019; 39:1838-1854. [PMID: 31211374 DOI: 10.1093/treephys/tpz069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 05/09/2019] [Accepted: 06/04/2019] [Indexed: 06/09/2023]
Abstract
Given the importance of carbon allocation for plant performance and fitness, it is expected that competition and abiotic stress influence respiratory costs associated with stem wood biomass production and maintenance. In this study, stem respiration (R) was measured together with stem diameter increment in adult trees of eight co-occurring species in a sub-Mediterranean forest stand for 2 years. We estimated growth R (Rg), maintenance R (Rm) and the growth respiration coefficient (GRC) using two gas exchange methods: (i) estimating Rg as the product of growth and GRC (then Rm as R minus Rg) and (ii) estimating Rm from temperature-dependent kinetics of basal Rm at the dormant season (then Rg as R minus Rm). In both cases, stem basal-area growth rates governed intra-annual variation in R, Rg and Rm. Maximum annual Rm occurred slightly before or after maximum Rg. The mean contribution of Rm to R during the growing season ranged from 56% to 88% across species using method 1 and from 23% to 66% using method 2. An analysis accounting for the phylogenetic distance among species indicated that more shade-tolerant, faster growing species exhibited higher Rm and Rg than less shade-tolerant, slower growing ones, suggesting a balance between carbon supply and demand mediated by growth. However, GRC was not related to species growth rate, wood density, or drought and shade tolerance across the surveyed species nor across 27 tree species for which GRC was compiled. The GRC estimates based on wood chemical analysis were lower (0.19) than those based on gas exchange methods (0.35). These results give partial support to the hypothesis that wood production and maintenance costs are related to species ecology and highlight the divergence of respiratory parameters widely used in plant models according to the methodological approach applied to derive them.
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Affiliation(s)
- Jesús Rodríguez-Calcerrada
- Forest Genetics and Ecophysiology Research Group, School of Forestry Engineering, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Roberto L Salomón
- Forest Genetics and Ecophysiology Research Group, School of Forestry Engineering, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - Guillermo G Gordaliza
- Forest Genetics and Ecophysiology Research Group, School of Forestry Engineering, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - José C Miranda
- Forest Genetics and Ecophysiology Research Group, School of Forestry Engineering, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Eva Miranda
- Forest Genetics and Ecophysiology Research Group, School of Forestry Engineering, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Enrique G de la Riva
- Department of Ecology, Brandenburg University of Technology, 03046 Cottbus, Germany
| | - Luis Gil
- Forest Genetics and Ecophysiology Research Group, School of Forestry Engineering, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
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17
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Salomón RL, Steppe K, Crous KY, Noh NJ, Ellsworth DS. Elevated CO 2 does not affect stem CO 2 efflux nor stem respiration in a dry Eucalyptus woodland, but it shifts the vertical gradient in xylem [CO 2 ]. PLANT, CELL & ENVIRONMENT 2019; 42:2151-2164. [PMID: 30903994 DOI: 10.1111/pce.13550] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 03/12/2019] [Accepted: 03/20/2019] [Indexed: 06/09/2023]
Abstract
To quantify stem respiration (RS ) under elevated CO2 (eCO2 ), stem CO2 efflux (EA ) and CO2 flux through the xylem (FT ) should be accounted for, because part of respired CO2 is transported upwards with the sap solution. However, previous studies have used EA as a proxy of RS , which could lead to equivocal conclusions. Here, to test the effect of eCO2 on RS , both EA and FT were measured in a free-air CO2 enrichment experiment located in a mature Eucalyptus native forest. Drought stress substantially reduced EA and RS , which were unaffected by eCO2 , likely as a consequence of its neutral effect on stem growth in this phosphorus-limited site. However, xylem CO2 concentration measured near the stem base was higher under eCO2 , and decreased along the stem resulting in a negative contribution of FT to RS , whereas the contribution of FT to RS under ambient CO2 was positive. Negative FT indicates net efflux of CO2 respired below the monitored stem segment, likely coming from the roots. Our results highlight the role of nutrient availability on the dependency of RS on eCO2 and suggest stimulated root respiration under eCO2 that may shift vertical gradients in xylem [CO2 ] confounding the interpretation of EA measurements.
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Affiliation(s)
- Roberto L Salomón
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, 9000, Ghent, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, 9000, Ghent, Belgium
| | - Kristine Y Crous
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, 2751, Australia
| | - Nam Jin Noh
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, 2751, Australia
| | - David S Ellsworth
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, 2751, Australia
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18
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Salomón RL, De Roo L, Bodé S, Boeckx P, Steppe K. Isotope ratio laser spectroscopy to disentangle xylem-transported from locally respired CO2 in stem CO2 efflux. TREE PHYSIOLOGY 2019; 39:819-830. [PMID: 30726992 DOI: 10.1093/treephys/tpy152] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 12/18/2018] [Accepted: 01/02/2019] [Indexed: 06/09/2023]
Abstract
Respired CO2 in woody tissues radially diffuses to the atmosphere or it is transported upward with the transpiration stream, making the origin of CO2 in stem CO2 efflux (EA) uncertain, which may confound stem respiration (RS) estimates. An aqueous 13C-enriched solution was infused into stems of Populus tremula L. trees, and real-time measurements of 13C-CO2 and 12C-CO2 in EA were performed via Cavity Ring Down Laser Spectroscopy (CRDS). The contribution of locally respired CO2 (LCO2) and xylem-transported CO2 (TCO2) to EA was estimated from their different isotopic composition. Mean daily values of TCO2/EA ranged from 13% to 38%, evidencing the notable role that xylem CO2 transport plays in the assessment of stem respiration. Mean daily TCO2/EA did not differ between treatments of drought stress and light exclusion of woody tissues, but they showed different TCO2/EA dynamics on a sub-daily time scale. Sub-daily CO2 diffusion patterns were explained by a light-induced axial CO2 gradient ascribed to woody tissue photosynthesis, and the resistance to radial CO2 diffusion determined by bark water content. Here, we demonstrate the outstanding potential of CRDS paired with 13C-CO2 labelling to advance in the understanding of CO2 movement at the plant-atmosphere interface and the respiratory physiology in woody tissues.
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Affiliation(s)
- Roberto L Salomón
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Linus De Roo
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Samuel Bodé
- Isotope Bioscience Laboratory - ISOFYS, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium
| | - Pascal Boeckx
- Isotope Bioscience Laboratory - ISOFYS, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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19
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Darenova E, Szatniewska J, Acosta M, Pavelka M. Variability of stem CO2 efflux response to temperature over the diel period. TREE PHYSIOLOGY 2019; 39:877-887. [PMID: 30597110 DOI: 10.1093/treephys/tpy134] [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: 06/08/2018] [Revised: 10/22/2018] [Accepted: 11/20/2018] [Indexed: 06/09/2023]
Abstract
This study presents results from continuous measurements of stem CO2 efflux carried out for seven growing seasons in a young Norway spruce forest. The objective of the study was to determine differences in temperature sensitivity of stem CO2 efflux (Q10) during night (when sap flow is zero or nearly zero), during early afternoon (when the maximum rate of sap flow occurs) and during two transition periods between the aforementioned periods. The highest Q10 was recorded during the period of zero sap flow, while the lowest Q10 was observed in period of the highest sap flow. Calculating Q10 using only data from the period of zero sap flow resulted in a Q10 that was higher by as much as 19% compared with Q10 calculated using 24 h data. On the other hand, basing the calculation on data from the period of the highest sap flow yielded 5.6% lower Q10 than if 24 h data were used. Considering that change in CO2 efflux lagged in time behind changing stem temperature, there was only a small effect on calculated Q10 for periods with zero and the highest sap flow. A larger effect of the time lag (by as much as 15%) was observed for the two transition periods. Stem CO2 efflux was modelled based on the night CO2 efflux response to temperature. This model had a tendency to overestimate CO2 efflux during daytime, thus indicating potential daytime depression of stem CO2 efflux compared with the values predicated on the basis of temperature caused by CO2 transport upward in the sap flow. This view was supported by our results inasmuch as the overestimation grew with sap flow that was modelled on the basis of photosynthetically active radiation and vapour pressure deficit.
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Affiliation(s)
- Eva Darenova
- Global Change Research Institute CAS, v.v.i., Belidla 4a, Brno, Czech Republic
| | - Justyna Szatniewska
- Global Change Research Institute CAS, v.v.i., Belidla 4a, Brno, Czech Republic
| | - Manuel Acosta
- Global Change Research Institute CAS, v.v.i., Belidla 4a, Brno, Czech Republic
| | - Marian Pavelka
- Global Change Research Institute CAS, v.v.i., Belidla 4a, Brno, Czech Republic
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20
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Fatichi S, Pappas C, Zscheischler J, Leuzinger S. Modelling carbon sources and sinks in terrestrial vegetation. THE NEW PHYTOLOGIST 2019; 221:652-668. [PMID: 30339280 DOI: 10.1111/nph.15451] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 08/12/2018] [Indexed: 05/06/2023]
Abstract
Contents Summary 652 I. Introduction 652 II. Discrepancy in predicting the effects of rising [CO2 ] on the terrestrial C sink 655 III. Carbon and nutrient storage in plants and its modelling 656 IV. Modelling the source and the sink: a plant perspective 657 V. Plant-scale water and Carbon flux models 660 VI. Challenges for the future 662 Acknowledgements 663 Authors contributions 663 References 663 SUMMARY: The increase in atmospheric CO2 in the future is one of the most certain projections in environmental sciences. Understanding whether vegetation carbon assimilation, growth, and changes in vegetation carbon stocks are affected by higher atmospheric CO2 and translating this understanding in mechanistic vegetation models is of utmost importance. This is highlighted by inconsistencies between global-scale studies that attribute terrestrial carbon sinks to CO2 stimulation of gross and net primary production on the one hand, and forest inventories, tree-scale studies, and plant physiological evidence showing a much less pronounced CO2 fertilization effect on the other hand. Here, we review how plant carbon sources and sinks are currently described in terrestrial biosphere models. We highlight an uneven representation of complexity between the modelling of photosynthesis and other processes, such as plant respiration, direct carbon sinks, and carbon allocation, largely driven by available observations. Despite a general lack of data on carbon sink dynamics to drive model improvements, ways forward toward a mechanistic representation of plant carbon sinks are discussed, leveraging on results obtained from plant-scale models and on observations geared toward model developments.
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Affiliation(s)
- Simone Fatichi
- Institute of Environmental Engineering, ETH Zurich, Stefano Franscini Platz 5, 8093, Zurich, Switzerland
| | - Christoforos Pappas
- Département de géographie and Centre d'études nordiques, Université de Montréal, Montreal, QC, H2V 2B8, Canada
| | - Jakob Zscheischler
- Institute for Atmospheric and Climate Science, ETH Zurich, Universitätstrasse 16, 8092, Zurich, Switzerland
| | - Sebastian Leuzinger
- Institute for Applied Ecology New Zealand, School of Science, Auckland University of Technology, Wakefield Street 46, 1142, Auckland, New Zealand
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Wittmann C, Pfanz H. More than just CO 2 -recycling: corticular photosynthesis as a mechanism to reduce the risk of an energy crisis induced by low oxygen. THE NEW PHYTOLOGIST 2018; 219:551-564. [PMID: 29767842 DOI: 10.1111/nph.15198] [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: 11/20/2017] [Accepted: 03/19/2018] [Indexed: 06/08/2023]
Abstract
Reassimilation of internal CO2 via corticular photosynthesis (PScort ) has an important effect on the carbon economy of trees. However, little is known about its role as a source of O2 supply to the stem parenchyma and its implications in consumption and movement of O2 within trees. PScort of young Populus nigra (black poplar) trees was investigated by combining optical micro-optode measurements with monitoring of stem chlorophyll fluorescence. During times of zero sap flow in spring, stem oxygen concentrations (cO2 ) exhibited large temporal changes. In the sapwood, over 80% of diurnal changes in cO2 could be explained by respiration rates (Rd(mod) ). In the cortex, photosynthetic oxygen release during the day altered this relationship. With daytime illumination, oxygen levels in the cortex steadily increased from subambient and even exhibited a diel period of superoxia of up to 110% (% air sat.). By contrast, in the sapwood, cO2 never reached ambient levels; the diurnal oxygen deficit was up to 25% of air saturation. Our results confirm that PScort is not only a CO2 -recycling mechanism, it is also a mechanism to actively raise the cortical O2 concentration and counteract temporal/spatial hypoxia inside plant stems.
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Affiliation(s)
- Christiane Wittmann
- Department of Applied Botany and Volcano Biology, University of Duisburg-Essen, Essen, 45117, Germany
| | - Hardy Pfanz
- Department of Applied Botany and Volcano Biology, University of Duisburg-Essen, Essen, 45117, Germany
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