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Dukat P, Hölttä T, Oren R, Salmon Y, Urbaniak M, Vesala T, Aalto J, Lintunen A. Partitioning seasonal stem carbon dioxide efflux into stem respiration, bark photosynthesis, and transport-related flux in Scots pine. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:4944-4959. [PMID: 38779859 PMCID: PMC11350082 DOI: 10.1093/jxb/erae242] [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: 10/23/2023] [Accepted: 05/22/2024] [Indexed: 05/25/2024]
Abstract
Stem CO2 efflux is an important component of the carbon balance in forests. The efflux is considered to principally reflect the net result of two dominating and opposing processes: stem respiration and stem photosynthesis. In addition, transport of CO2 in xylem sap is thought to play an appreciable role in affecting the net flux. This work presents an approach to partition stem CO2 efflux among these processes using sap-flux data and CO2-exchange measurements from dark and transparent chambers placed on mature Scots pine (Pinus sylvestris) trees. Seasonal changes and monthly parameters describing the studied processes were determined. Respiration contributed most to stem net CO2 flux, reaching up to 79% (considering the sum of the absolute values of stem respiration, stem photosynthesis, and flux from CO2 transported in xylem sap to be 100%) in June, when stem growth was greatest. The contribution of photosynthesis accounted for up to 13% of the stem net CO2 flux, increasing over the monitoring period. CO2 transported axially with sap flow decreased towards the end of the growing season. At a reference temperature, respiration decreased starting around midsummer, while its temperature sensitivity increased during the summer. A decline was observed for photosynthetic quantum yield around midsummer together with a decrease in light-saturation point. The proposed approach facilitates modeling net stem CO2 flux at a range of time scales.
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Affiliation(s)
- Paulina Dukat
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
- Laboratory of Meteorology, Department of Construction and Geoengineering, Faculty of Environmental Engineering and Mechanical Engineering, Poznan University of Life Sciences, Piątkowska 94, 60-649 Poznań, Poland
| | - Teemu Hölttä
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
| | - Ram Oren
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
- Nicholas School of the Environment & Pratt School of Engineering, Duke University, Durham NC, USA
| | - Yann Salmon
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
- Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
| | - Marek Urbaniak
- Laboratory of Meteorology, Department of Construction and Geoengineering, Faculty of Environmental Engineering and Mechanical Engineering, Poznan University of Life Sciences, Piątkowska 94, 60-649 Poznań, Poland
| | - Timo Vesala
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
- Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
| | - Juho Aalto
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
| | - Anna Lintunen
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
- Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
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Ge M, Korrensalo A, Laiho R, Kohl L, Lohila A, Pihlatie M, Li X, Laine AM, Anttila J, Putkinen A, Wang W, Koskinen M. Plant-mediated CH 4 exchange in wetlands: A review of mechanisms and measurement methods with implications for modelling. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 914:169662. [PMID: 38159777 DOI: 10.1016/j.scitotenv.2023.169662] [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: 07/03/2023] [Revised: 12/22/2023] [Accepted: 12/22/2023] [Indexed: 01/03/2024]
Abstract
Plant-mediated CH4 transport (PMT) is the dominant pathway through which soil-produced CH4 can escape into the atmosphere and thus plays an important role in controlling ecosystem CH4 emission. PMT is affected by abiotic and biotic factors simultaneously, and the effects of biotic factors, such as the dominant plant species and their traits, can override the effects of abiotic factors. Increasing evidence shows that plant-mediated CH4 fluxes include not only PMT, but also within-plant CH4 production and oxidation due to the detection of methanogens and methanotrophs attached to the shoots. Despite the inter-species and seasonal differences, and the probable contribution of within-plant microbes to total plant-mediated CH4 exchange (PME), current process-based ecosystem models only estimate PMT based on the bulk biomass or leaf area index of aerenchymatous plants. We highlight five knowledge gaps to which more research efforts should be devoted. First, large between-species variation, even within the same family, complicates general estimation of PMT, and calls for further work on the key dominant species in different types of wetlands. Second, the interface (rhizosphere-root, root-shoot, or leaf-atmosphere) and plant traits controlling PMT remain poorly documented, but would be required for generalizations from species to relevant functional groups. Third, the main environmental controls of PMT across species remain uncertain. Fourth, the role of within-plant CH4 production and oxidation is poorly quantified. Fifth, the simplistic description of PMT in current process models results in uncertainty and potentially high errors in predictions of the ecosystem CH4 flux. Our review suggest that flux measurements should be conducted over multiple growing seasons and be paired with trait assessment and microbial analysis, and that trait-based models should be developed. Only then we are capable to accurately estimate plant-mediated CH4 emissions, and eventually ecosystem total CH4 emissions at both regional and global scales.
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Affiliation(s)
- Mengyu Ge
- Department of Agricultural Sciences, University of Helsinki, PO Box 56, Helsinki 00014, Finland; Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, University of Helsinki, PO Box 56, Helsinki 00014, Finland.
| | - Aino Korrensalo
- Department of Environmental and Biological Sciences, University of Eastern Finland, PO Box 111, Kuopio 80101, Finland; Natural Resources Institute Finland, Latokartanonkaari 9, Helsinki 00790, Finland
| | - Raija Laiho
- Natural Resources Institute Finland, Latokartanonkaari 9, Helsinki 00790, Finland
| | - Lukas Kohl
- Department of Agricultural Sciences, University of Helsinki, PO Box 56, Helsinki 00014, Finland; Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, University of Helsinki, PO Box 56, Helsinki 00014, Finland; Department of Environmental and Biological Sciences, University of Eastern Finland, PO Box 111, Kuopio 80101, Finland
| | - Annalea Lohila
- Finnish Meteorological Institute, Erik Palménin aukio 1, Helsinki 00560, Finland
| | - Mari Pihlatie
- Department of Agricultural Sciences, University of Helsinki, PO Box 56, Helsinki 00014, Finland; Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, University of Helsinki, PO Box 56, Helsinki 00014, Finland; Department of Agricultural Sciences, Viikki Plant Science Centre (ViPS), University of Helsinki, PO Box 56, 00014 Helsinki, Finland
| | - Xuefei Li
- Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, University of Helsinki, PO Box 56, Helsinki 00014, Finland
| | - Anna M Laine
- Geological Survey of Finland, PO Box 1237, 70211 Kuopio, Finland
| | - Jani Anttila
- Natural Resources Institute Finland, Latokartanonkaari 9, Helsinki 00790, Finland
| | - Anuliina Putkinen
- Department of Agricultural Sciences, University of Helsinki, PO Box 56, Helsinki 00014, Finland; Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, University of Helsinki, PO Box 56, Helsinki 00014, Finland
| | - Weifeng Wang
- College of Biology and the Environment, Nanjing Forestry University, 210037 Nanjing, China
| | - Markku Koskinen
- Department of Agricultural Sciences, University of Helsinki, PO Box 56, Helsinki 00014, Finland; Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, University of Helsinki, PO Box 56, Helsinki 00014, Finland
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3
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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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Han X, Jing Y, Xu C, Gao L, Li M, Liu Y, Qi H. Root-Zone CO2 Concentration Affects Partitioning and Assimilation of Carbon in Oriental Melon Seedlings. Int J Mol Sci 2022; 23:ijms231810694. [PMID: 36142602 PMCID: PMC9500774 DOI: 10.3390/ijms231810694] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 09/06/2022] [Accepted: 09/09/2022] [Indexed: 11/26/2022] Open
Abstract
Root-zone CO2 is essential for plant growth and metabolism. However, the partitioning and assimilation processes of CO2 absorbed by roots remain unclear in various parts of the oriental melon. We investigated the time at which root-zone CO2 enters the oriental melon root system, and its distribution in different parts of the plant, using 13C stable isotopic tracer experiments, as well as the effects of high root-zone CO2 on leaf carbon assimilation-related enzyme activities and gene expressions under 0.2%, 0.5% and 1% root-zone CO2 concentrations. The results showed that oriental melon roots could absorb CO2 and transport it quickly to the stems and leaves. The distribution of 13C in roots, stems and leaves increased with an increase in the labeled root-zone CO2 concentration, and the δ13C values in roots, stems and leaves increased initially, and then decreased with an increase in feeding time, reaching a peak at 24 h after 13C isotope labeling. The total accumulation of 13C in plants under the 0.5% and 1% 13CO2 concentrations was lower than that in the 0.2% 13CO2 treatment. However, the distributional proportion of 13C in leaves under 0.5% and 1% 13CO2 was significantly higher than that under the 0.2% CO2 concentration. Photosynthetic carbon assimilation-related enzyme activities and gene expressions in the leaves of oriental melon seedlings were inhibited after 9 days of high root-zone CO2 treatment. According to these results, oriental melon plants’ carbon distribution was affected by long-term high root-zone CO2, and reduced the carbon assimilation ability of the leaves. These findings provide a basis for the further quantification of the contribution of root-zone CO2 to plant communities in natural field conditions.
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Affiliation(s)
- Xintong Han
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
- Key Laboratory of Protected Horticulture Ministry of Education, Shenyang 110866, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology, Shenyang 110866, China
| | - Yuna Jing
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
- Key Laboratory of Protected Horticulture Ministry of Education, Shenyang 110866, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology, Shenyang 110866, China
| | - Chuanqiang Xu
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
- Key Laboratory of Protected Horticulture Ministry of Education, Shenyang 110866, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology, Shenyang 110866, China
| | - Lijia Gao
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
- Key Laboratory of Protected Horticulture Ministry of Education, Shenyang 110866, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology, Shenyang 110866, China
| | - Minghui Li
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
- Key Laboratory of Protected Horticulture Ministry of Education, Shenyang 110866, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology, Shenyang 110866, China
| | - Yiling Liu
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
- Key Laboratory of Protected Horticulture Ministry of Education, Shenyang 110866, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology, Shenyang 110866, China
- Correspondence: (Y.L.); (H.Q.)
| | - Hongyan Qi
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
- Key Laboratory of Protected Horticulture Ministry of Education, Shenyang 110866, China
- National & Local Joint Engineering Research Center of Northern Horticultural Facilities Design & Application Technology, Shenyang 110866, China
- Correspondence: (Y.L.); (H.Q.)
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5
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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: 6] [Impact Index Per Article: 2.0] [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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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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7
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Marler TE, Krishnapillai MV. Vertical Strata and Stem Carbon Dioxide Efflux in Cycas Trees. PLANTS (BASEL, SWITZERLAND) 2020; 9:E230. [PMID: 32054006 PMCID: PMC7076351 DOI: 10.3390/plants9020230] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 02/02/2020] [Accepted: 02/09/2020] [Indexed: 11/16/2022]
Abstract
Stem respiration is influenced by the vertical location of tree stems, but the influence of vertical location on stem respiration in a representative cycad species has not been determined. We quantified the influence of vertical strata on stem carbon dioxide efflux (Es) for six arborescent Cycas L. species to characterize this component of stem respiration and ecosystem carbon cycling. The influence of strata on Es was remarkably consistent among the species, with a stable baseline flux characterizing the full mid-strata of the pachycaulous stems and an increase in Es at the lowest and highest strata. The mid-strata flux ranged from 1.8 µmol·m-2·s-1 for Cycas micronesica K.D. Hill to 3.5 µmol·m-2·s-1 for Cycas revoluta Thunb. For all species, Es increased about 30% at the lowest stratum and about 80% at the highest stratum. A significant quadratic model adequately described the Es patterns for all six species. The increase of Es at the lowest stratum was consistent with the influence of root-respired carbon dioxide entering the stem via sap flow, then contributing to Es via radial conductance to the stem surface. The substantial increase in Es at the highest stratum is likely a result of the growth and maintenance respiration of the massive cycad primary thickening meristem that constructs the unique pachycaulous cycad stem.
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Affiliation(s)
- Thomas E. Marler
- College of Natural and Applied Sciences, University of Guam, Mangilao, Guam 96923, USA
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8
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Katayama A, Kume T, Ichihashi R, Nakagawa M. Vertical variation in wood CO2 efflux is not uniformly related to height: measurement across various species and sizes of Bornean tropical rainforest trees. TREE PHYSIOLOGY 2019; 39:1000-1008. [PMID: 30976804 DOI: 10.1093/treephys/tpz022] [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: 10/02/2018] [Revised: 02/05/2019] [Accepted: 04/02/2019] [Indexed: 06/09/2023]
Abstract
Limited knowledge about vertical variation in wood CO2 efflux (Rwood) is still a cause of uncertainty in Rwood estimates at individual and ecosystem scales. Although previous studies found higher Rwood in the canopy, they examined several tree species of similar size. In contrast, in the present study, we measured vertical variation in Rwood for 18 trees including 13 species, using a canopy crane for a more precise determination of the vertical variation in Rwood, for various species and sizes of trees in order to examine the factors affecting vertical variation in Rwood and thus, to better understand the effect of taking into account the vertical and inter-individual variation on estimates of Rwood at the individual scale. We did not find any clear pattern of vertical variation; Rwood increased significantly with measurement height for only one tree, while it decreased for two more trees, and was not significantly related with measurement height in 15 other trees. Canopy to breast height Rwood ratio was not related to diameter at breast height or crown ratio, which supposedly are factors affecting vertical variation in Rwood. On average, Rwood estimates at individual scale, considering inter-individual variation but ignoring vertical variation, were only 6% higher than estimates considering both forms of variation. However, estimates considering vertical variation, while ignoring inter-individual variation, were 13% higher than estimates considering both forms of variation. These results suggest that individual measurements at breast height are more important for estimating Rwood at the individual scale, and that any error in Rwood estimation at this scale, due to the absence of any more measurements along tree height, is really quite negligible. This study measured various species and sizes of trees, which may be attributed to no clear vertical variation because factors causing vertical variation can differ among species and sizes.
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Affiliation(s)
- Ayumi Katayama
- Shiiba Research Forest, Kyushu University, Shiiba, Miyazaki, Japan
| | - Tomonori Kume
- Kasuya Research Forest, Kyushu University, Sasaguri, Fukuoka, Japan
- School of Forestry and Resource Conservation, National Taiwan University, Taipei, Taiwan
| | - Ryuji Ichihashi
- Shiiba Research Forest, Kyushu University, Shiiba, Miyazaki, Japan
| | - Michiko Nakagawa
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, Japan
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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: 10] [Impact Index Per Article: 2.0] [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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10
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Rissanen K, Hölttä T, Bäck J. Transpiration directly regulates the emissions of water-soluble short-chained OVOCs. PLANT, CELL & ENVIRONMENT 2018; 41:2288-2298. [PMID: 29676016 DOI: 10.1111/pce.13318] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 03/29/2018] [Accepted: 04/02/2018] [Indexed: 05/10/2023]
Abstract
Most plant-based emissions of volatile organic compounds are considered mainly temperature dependent. However, certain oxygenated volatile organic compounds (OVOCs) have high water solubility; thus, also stomatal conductance could regulate their emissions from shoots. Due to their water solubility and sources in stem and roots, it has also been suggested that their emissions could be affected by transport in the xylem sap. Yet further understanding on the role of transport has been lacking until present. We used shoot-scale long-term dynamic flux data from Scots pines (Pinus sylvestris) to analyse the effects of transpiration and transport in xylem sap flow on emissions of 3 water-soluble OVOCs: methanol, acetone, and acetaldehyde. We found a direct effect of transpiration on the shoot emissions of the 3 OVOCs. The emissions were best explained by a regression model that combined linear transpiration and exponential temperature effects. In addition, a structural equation model indicated that stomatal conductance affects emissions mainly indirectly, by regulating transpiration. A part of the temperature's effect is also indirect. The tight coupling of shoot emissions to transpiration clearly evidences that these OVOCs are transported in the xylem sap from their sources in roots and stem to leaves and to ambient air.
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Affiliation(s)
- K Rissanen
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, FIN-00014, Finland
| | - T Hölttä
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, FIN-00014, Finland
| | - J Bäck
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, FIN-00014, Finland
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11
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Rowland L, da Costa ACL, Oliveira AAR, Oliveira RS, Bittencourt PL, Costa PB, Giles AL, Sosa AI, Coughlin I, Godlee JL, Vasconcelos SS, Junior JAS, Ferreira LV, Mencuccini M, Meir P. Drought stress and tree size determine stem CO 2 efflux in a tropical forest. THE NEW PHYTOLOGIST 2018; 218:1393-1405. [PMID: 29397028 PMCID: PMC5969101 DOI: 10.1111/nph.15024] [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: 10/11/2017] [Accepted: 12/22/2017] [Indexed: 05/10/2023]
Abstract
CO2 efflux from stems (CO2_stem ) accounts for a substantial fraction of tropical forest gross primary productivity, but the climate sensitivity of this flux remains poorly understood. We present a study of tropical forest CO2_stem from 215 trees across wet and dry seasons, at the world's longest running tropical forest drought experiment site. We show a 27% increase in wet season CO2_stem in the droughted forest relative to a control forest. This was driven by increasing CO2_stem in trees 10-40 cm diameter. Furthermore, we show that drought increases the proportion of maintenance to growth respiration in trees > 20 cm diameter, including large increases in maintenance respiration in the largest droughted trees, > 40 cm diameter. However, we found no clear taxonomic influence on CO2_stem and were unable to accurately predict how drought sensitivity altered ecosystem scale CO2_stem , due to substantial uncertainty introduced by contrasting methods previously employed to scale CO2_stem fluxes. Our findings indicate that under future scenarios of elevated drought, increases in CO2_stem may augment carbon losses, weakening or potentially reversing the tropical forest carbon sink. However, due to substantial uncertainties in scaling CO2_stem fluxes, stand-scale future estimates of changes in stem CO2 emissions remain highly uncertain.
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Affiliation(s)
- Lucy Rowland
- College of Life and Environmental SciencesUniversity of ExeterExeterEX4 4RJUK
| | | | | | | | | | | | | | - Azul I. Sosa
- Instituto de BiologiaUNICAMPCampinasSP13083‐970Brasil
| | - Ingrid Coughlin
- Departamento de BiologiaFFCLRPUniversidade de São PauloRibeirão PretoSP14040‐900Brasil
| | - John L. Godlee
- School of GeoSciencesUniversity of EdinburghEdinburghEH9 3FFUK
| | | | - João A. S. Junior
- Instituto de GeosciênciasUniversidade Federal do ParáBelémPA66075‐110Brasil
| | | | | | - Patrick Meir
- School of GeoSciencesUniversity of EdinburghEdinburghEH9 3FFUK
- Research School of BiologyAustralian National UniversityCanberraACT2601Australia
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12
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Salomón RL, De Schepper V, Valbuena-Carabaña M, Gil L, Steppe K. Daytime depression in temperature-normalised stem CO 2 efflux in young poplar trees is dominated by low turgor pressure rather than by internal transport of respired CO 2. THE NEW PHYTOLOGIST 2018; 217:586-598. [PMID: 28984360 DOI: 10.1111/nph.14831] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 09/01/2017] [Indexed: 06/07/2023]
Abstract
Daytime decreases in temperature-normalised stem CO2 efflux (EA_D ) are commonly ascribed to internal transport of respired CO2 (FT ) or to an attenuated respiratory activity due to lowered turgor pressure. The two are difficult to separate as they are simultaneously driven by sap flow dynamics. To achieve combined gradients in turgor pressure and FT , sap flow rates in poplar trees were manipulated through severe defoliation, severe drought, moderate defoliation and moderate drought. Turgor pressure was mechanistically modelled using measurements of sap flow, stem diameter variation, and soil and stem water potential. A mass balance approach considering internal and external CO2 fluxes was applied to estimate FT . Under well-watered control conditions, both turgor pressure and sap flow, as a proxy of FT , were reliable predictors of EA_D . After tree manipulation, only turgor pressure was a robust predictor of EA_D . Moreover, FT accounted for < 15% of EA_D . Our results suggest that daytime reductions in turgor pressure and associated constrained growth are the main cause of EA_D in young poplar trees. Turgor pressure is determined by both carbohydrate supply and water availability, and should be considered to improve our widely used but inaccurate temperature-based predictions of woody tissue respiration in global models.
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Affiliation(s)
- Roberto L Salomón
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000, Ghent, Belgium
- Forest Genetics and Ecophysiology Research Group, E.T.S. Forestry Engineering, Technical University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Veerle De Schepper
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000, Ghent, Belgium
| | - María Valbuena-Carabaña
- Forest Genetics and Ecophysiology Research Group, E.T.S. Forestry Engineering, Technical University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Luis Gil
- Forest Genetics and Ecophysiology Research Group, E.T.S. Forestry Engineering, Technical University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain
| | - Kathy Steppe
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000, Ghent, Belgium
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13
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Fan H, McGuire MA, Teskey RO. Effects of stem size on stem respiration and its flux components in yellow-poplar (Liriodendron tulipifera L.) trees. TREE PHYSIOLOGY 2017; 37:1536-1545. [PMID: 28985420 DOI: 10.1093/treephys/tpx084] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 06/07/2017] [Indexed: 06/07/2023]
Abstract
Carbon dioxide (CO2) released from respiring cells in the stems of trees (RS) can diffuse radially to the atmosphere (EA) or dissolve in xylem sap and move internally in the tree (FT). Previous studies have observed that EA decreases as stem or branch diameter increases, but the cause of this relationship has not been determined, nor has the relationship been confirmed between stem diameter and RS, which includes both EA and FT. In this study, for the first time the mass balance technique was used to estimate RS of stems of Liriodendron tulipifera L. trees of different diameters, ranging from 16 to 60 cm, growing on the same site. The magnitude of the component fluxes scaled with tree size. Among the five trees, the contribution of EA to RS decreased linearly with increasing stem diameter and sapwood area while the contribution of FT to RS increased linearly with stem diameter and sapwood area. For the smallest tree EA was 86% of RS but it was only 46% of RS in the largest tree. As tree size increased a greater proportion of respired CO2 dissolved in sap and remained within the tree. Due to increase in FT with tree size, we observed that trees of different sizes had the same RS even though they had different EA. This appears to explain why the EA of stems and branches decreases as their size increases.
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Affiliation(s)
- Hailan Fan
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China
- Fujian Provincial Key Laboratory of Forest Ecosystem Processing and Management, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Mary Anne McGuire
- Warnell School of Forestry and Natural Resources, 180 E. Green Street, University of Georgia, Athens, GA 30602, USA
| | - Robert O Teskey
- Warnell School of Forestry and Natural Resources, 180 E. Green Street, University of Georgia, Athens, GA 30602, USA
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14
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Han F, Wang X, Zhou H, Li Y, Hu D. Temporal dynamics and vertical variations in stem CO 2 efflux of Styphnolobium japonicum. JOURNAL OF PLANT RESEARCH 2017; 130:845-858. [PMID: 28536983 DOI: 10.1007/s10265-017-0951-3] [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: 10/18/2016] [Accepted: 04/14/2017] [Indexed: 06/07/2023]
Abstract
CO2 efflux (ECO2) from stems and branches is highly variable within trees. To investigate the mechanisms underlying the temporal dynamics and vertical variations in ECO2, we measured the stem ECO2 by infrared gas analysis (IRGA) and meteorological conditions at 10 different heights from 0.1 to 3.7 m aboveground on two consecutive days every month for 1 year in six Styphnolobium japonicum trees with a similar size. The results indicated that the seasonal change in ECO2 roughly followed the seasonal variations in woody tissue temperature (TW) and stem radial diameter increment (Di). Together, TW and Di explained the monthly change in ECO2, and the contributions of TW and Di changed with the stem positions and growth stages. The diurnal patterns of ECO2 differed greatly between the growing and dormant season, showing a bimodal distribution with an obvious midday depression in the former and a unimodal distribution in the latter. The strong vertical variation in the day-time ECO2 of the growing season was mainly caused by the vertical gradients of TW, Di and difference in sapwood volume per unit of the stem surface along the trunk. The temperature-sensitivity coefficient (Q10) was not constant, as assumed in some models, but was instead vertically altered and highly dependent on the measurement temperature. For all stem positions, the highest Q10 value appeared at approximately 5 °C, and both higher and lower temperatures decreased Q10. Our study demonstrated that application of a constant Q10 would cause an estimation error when scaling up chamber-based measurements to annual carbon budgets at the whole-stem level.
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Affiliation(s)
- Fengsen Han
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, Republic of China
- University of Chinese Academy of Sciences, Beijing, 100049, Republic of China
| | - Xiaolin Wang
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, Republic of China
| | - Hongxuan Zhou
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, Republic of China
| | - Yuanzheng Li
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, Republic of China
- University of Chinese Academy of Sciences, Beijing, 100049, Republic of China
| | - Dan Hu
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, Republic of China.
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15
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Zachariah EJ, Sabulal B, Nair DNK, Johnson AJ, Kumar CSP. Carbon dioxide emission from bamboo culms. PLANT BIOLOGY (STUTTGART, GERMANY) 2016; 18:400-405. [PMID: 26802362 DOI: 10.1111/plb.12435] [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: 01/14/2016] [Accepted: 01/18/2016] [Indexed: 06/05/2023]
Abstract
Bamboos are one of the fastest growing plants on Earth, and are widely considered to have high ability to capture and sequester atmospheric carbon, and consequently to mitigate climate change. We tested this hypothesis by measuring carbon dioxide (CO2 ) emissions from bamboo culms and comparing them with their biomass sequestration potential. We analysed diurnal effluxes from Bambusa vulgaris culm surface and gas mixtures inside hollow sections of various bamboos using gas chromatography. Corresponding variations in gas pressure inside the bamboo section and culm surface temperature were measured. SEM micrographs of rhizome and bud portions of bamboo culms were also recorded. We found very high CO2 effluxes from culm surface, nodes and buds of bamboos. Positive gas pressure and very high concentrations of CO2 were observed inside hollow sections of bamboos. The CO2 effluxes observed from bamboos were very high compared to their carbon sequestration potential. Our measurements suggest that bamboos are net emitters of CO2 during their lifespan.
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Affiliation(s)
- E J Zachariah
- Atmospheric Sciences Division, National Centre for Earth Science Studies, Thiruvananthapuram, India
| | - B Sabulal
- Phytochemistry and Phytopharmacology Division, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Thiruvananthapuram, India
| | - D N K Nair
- Atmospheric Sciences Division, National Centre for Earth Science Studies, Thiruvananthapuram, India
| | - A J Johnson
- Phytochemistry and Phytopharmacology Division, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Thiruvananthapuram, India
| | - C S P Kumar
- Atmospheric Sciences Division, National Centre for Earth Science Studies, Thiruvananthapuram, India
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16
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Rodríguez-Calcerrada J, López R, Salomón R, Gordaliza GG, Valbuena-Carabaña M, Oleksyn J, Gil L. Stem CO2 efflux in six co-occurring tree species: underlying factors and ecological implications. PLANT, CELL & ENVIRONMENT 2015; 38:1104-1115. [PMID: 25292455 DOI: 10.1111/pce.12463] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 09/26/2014] [Accepted: 09/29/2014] [Indexed: 06/03/2023]
Abstract
Stem respiration plays a role in species coexistence and forest dynamics. Here we examined the intra- and inter-specific variability of stem CO2 efflux (E) in dominant and suppressed trees of six deciduous species in a mixed forest stand: Fagus sylvatica L., Quercus petraea [Matt.] Liebl, Quercus pyrenaica Willd., Prunus avium L., Sorbus aucuparia L. and Crataegus monogyna Jacq. We conducted measurements in late autumn. Within species, dominants had higher E per unit stem surface area (Es ) mainly because sapwood depth was higher than in suppressed trees. Across species, however, differences in Es corresponded with differences in the proportion of living parenchyma in sapwood and concentration of non-structural carbohydrates (NSC). Across species, Es was strongly and NSC marginally positively related with an index of drought tolerance, suggesting that slow growth of drought-tolerant trees is related to higher NSC concentration and Es . We conclude that, during the leafless period, E is indicative of maintenance respiration and is related with some ecological characteristics of the species, such as drought resistance; that sapwood depth is the main factor explaining variability in Es within species; and that the proportion of NSC in the sapwood is the main factor behind variability in Es among species.
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Affiliation(s)
- Jesús Rodríguez-Calcerrada
- Forest Genetics and Ecophysiology Research Group, School of Forestry Engineering, Technical University of Madrid, Madrid, 28040, Spain
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17
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Bloemen J, Bauweraerts I, De Vos F, Vanhove C, Vandenberghe S, Boeckx P, Steppe K. Fate of xylem-transported 11C- and 13C-labeled CO2 in leaves of poplar. PHYSIOLOGIA PLANTARUM 2015; 153:555-64. [PMID: 25142926 DOI: 10.1111/ppl.12262] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 07/02/2014] [Indexed: 05/26/2023]
Abstract
In recent studies, assimilation of xylem-transported CO2 has gained considerable attention as a means of recycling respired CO2 in trees. However, we still lack a clear and detailed picture on the magnitude of xylem-transported CO2 assimilation, in particular within leaf tissues. To this end, detached poplar leaves (Populus × canadensis Moench 'Robusta') were allowed to take up a dissolved (13)CO2 label serving as a proxy of xylem-transported CO2 entering the leaf from the branch. The uptake rate of the (13)C was manipulated by altering the vapor pressure deficit (VPD) (0.84, 1.29 and 1.83 kPa). Highest tissue enrichments were observed under the highest VPD. Among tissues, highest enrichment was observed in the petiole and the veins, regardless of the VPD treatment. Analysis of non-labeled leaves showed that some (13)C diffused from the labeled leaves and was fixed in the mesophyll of the non-labeled leaves. However, (13)C leaf tissue enrichment analysis with elemental analysis coupled to isotope ratio mass spectrometry was limited in spatial resolution at the leaf tissue level. Therefore, (11)C-based CO2 labeling combined with positron autoradiography was used and showed a more detailed spatial distribution within a single tissue, in particular in secondary veins. Therefore, in addition to (13)C, (11) C-based autoradiography can be used to study the fate of xylem-transported CO2 at leaf level, allowing the acquisition of data at a yet unprecedented resolution.
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Affiliation(s)
- Jasper Bloemen
- Laboratory of Plant Ecology, Ghent University, 9000, Gent, Belgium
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18
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Dařenová E, Pavelka M, Janouš D. Dynamics of temperature normalized stem CO<sub>2</sub> efflux in Norway spruce stand. ACTA UNIVERSITATIS AGRICULTURAE ET SILVICULTURAE MENDELIANAE BRUNENSIS 2014. [DOI: 10.11118/actaun201159060121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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19
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Yang Y, Zhao M, Xu X, Sun Z, Yin G, Piao S. Diurnal and seasonal change in stem respiration of Larix principis-rupprechtii trees, northern China. PLoS One 2014; 9:e89294. [PMID: 24586668 PMCID: PMC3935864 DOI: 10.1371/journal.pone.0089294] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 01/17/2014] [Indexed: 12/02/2022] Open
Abstract
Stem respiration is a critical and uncertain component of ecosystem carbon cycle. Few studies reported diurnal change in stem respiration as well as its linkage with climate. In this study, we investigated the diurnal and seasonal change in stem respiration and its linkage with environmental factors, in larch plantations of northern China from 2010 to 2012. The stem respiration per unit surface area (RS) showed clear diurnal cycles, ranging from 1.65±0.10 to 2.69±0.15 µmol m(-2) s(-1), increased after 6∶00, peaked at 15∶00 and then decreased. Both stem temperature and air temperature show similar diurnal pattern, while the diurnal pattern of air relative humidity is just the opposite to Rs. Similar to the diurnal cycles, seasonal change in RS followed the pattern of stem temperature. RS increased from May (1.28±0.07 µmol m(-2) s(-1)) when the stem temperature was relatively low and peaked in July (3.02±0.10 µmol m(-2) s(-1)) when the stem temperature was also the highest. Further regression analyses show that RS exponentially increases with increasing temperature, and the Q10 of Rs at mid daytime (1.97±0.17 at 12∶00 and 1.96±0.10 at 15∶00) is significantly lower than that of mid nighttime (2.60±0.14 at 00∶00 and 2.71±0.25 at 03∶00) Q10. This result not only implies that Rs is more sensitive to night than day warming, but also highlights that temperature responses of Rs estimated by only daytime measurement can lead to underestimated stem respiration increase under global warming, especially considering that temperature increase is faster during nighttime.
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Affiliation(s)
- Yan Yang
- Department of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China
| | - Miao Zhao
- Department of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China
| | - Xiangtao Xu
- Department of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China
- Department of Geosciences, Princeton University, Princeton, New Jersey, United States of America
| | - Zhenzhong Sun
- Department of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China
| | - Guodong Yin
- Department of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China
| | - Shilong Piao
- Department of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China
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20
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Bloemen J, Agneessens L, Van Meulebroek L, Aubrey DP, McGuire MA, Teskey RO, Steppe K. Stem girdling affects the quantity of CO2 transported in xylem as well as CO2 efflux from soil. THE NEW PHYTOLOGIST 2014; 201:897-907. [PMID: 24400900 DOI: 10.1111/nph.12568] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 09/26/2013] [Indexed: 05/24/2023]
Abstract
There is recent clear evidence that an important fraction of root-respired CO2 is transported upward in the transpiration stream in tree stems rather than fluxing to the soil. In this study, we aimed to quantify the contribution of root-respired CO2 to both soil CO2 efflux and xylem CO2 transport by manipulating the autotrophic component of belowground respiration. We compared soil CO2 efflux and the flux of root-respired CO2 transported in the transpiration stream in girdled and nongirdled 9-yr-old oak trees (Quercus robur) to assess the impact of a change in the autotrophic component of belowground respiration on both CO2 fluxes. Stem girdling decreased xylem CO2 concentration, indicating that belowground respiration contributes to the aboveground transport of internal CO2 . Girdling also decreased soil CO2 efflux. These results confirmed that root respiration contributes to xylem CO2 transport and that failure to account for this flux results in inaccurate estimates of belowground respiration when efflux-based methods are used. This research adds to the growing body of evidence that efflux-based measurements of belowground respiration underestimate autotrophic contributions.
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Affiliation(s)
- Jasper Bloemen
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Ghent University, Coupure links 653, 9000, Gent, Belgium
| | - Laura Agneessens
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Ghent University, Coupure links 653, 9000, Gent, Belgium
| | - Lieven Van Meulebroek
- Department of Veterinary Public Health and Food Safety, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium
| | - Doug P Aubrey
- Department of Biology, Georgia Southern University, PO Box 8042, Statesboro, GA, 30460-8042, USA
| | - Mary Anne McGuire
- Warnell School of Forestry and Natural Resources, University of Georgia, 180 East Green St, Athens, GA, 30602-2152, USA
| | - Robert O Teskey
- Warnell School of Forestry and Natural Resources, University of Georgia, 180 East Green St, Athens, GA, 30602-2152, USA
| | - Kathy Steppe
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Ghent University, Coupure links 653, 9000, Gent, Belgium
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21
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Pangala SR, Gowing DJ, Hornibrook ERC, Gauci V. Controls on methane emissions from Alnus glutinosa saplings. THE NEW PHYTOLOGIST 2014; 201:887-896. [PMID: 24219654 DOI: 10.1111/nph.12561] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 09/20/2013] [Indexed: 06/02/2023]
Abstract
Recent studies have confirmed significant tree-mediated methane emissions in wetlands; however, conditions and processes controlling such emissions are unclear. Here we identify factors that control the emission of methane from Alnus glutinosa. Methane fluxes from the soil surface, tree stem surfaces, leaf surfaces and whole mesocosms, pore water methane concentrations and physiological factors (assimilation rate, stomatal conductance and transpiration) were measured from 4-yr old A. glutinosa trees grown under two artificially controlled water-table positions. Up to 64% of methane emitted from the high water-table mesocosms was transported to the atmosphere through A. glutinosa. Stem emissions from 2 to 22 cm above the soil surface accounted for up to 42% of total tree-mediated methane emissions. Methane emissions were not detected from leaves and no relationship existed between leaf surface area and rates of tree-mediated methane emissions. Tree stem methane flux strength was controlled by the amount of methane dissolved in pore water and the density of stem lenticels. Our data show that stem surfaces dominate methane egress from A. glutinosa, suggesting that leaf area index is not a suitable approach for scaling tree-mediated methane emissions from all types of forested wetland.
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Affiliation(s)
- Sunitha R Pangala
- Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR), Department of Environment, Earth and Ecosystems, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
| | - David J Gowing
- Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR), Department of Environment, Earth and Ecosystems, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
| | - Edward R C Hornibrook
- School of Earth Sciences, Bristol Biogeochemistry Research Centre & Cabot Institute, University of Bristol, Will Memorial Building, Queen's Road, Bristol, BS8 1RJ, UK
| | - Vincent Gauci
- Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR), Department of Environment, Earth and Ecosystems, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
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22
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Bloemen J, McGuire MA, Aubrey DP, Teskey RO, Steppe K. Assimilation of xylem-transported CO2 is dependent on transpiration rate but is small relative to atmospheric fixation. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:2129-38. [PMID: 23580747 DOI: 10.1093/jxb/ert071] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The effect of transpiration rate on internal assimilation of CO2 released from respiring cells has not previously been quantified. In this study, detached branches of Populus deltoides were allowed to take up (13)CO2-labelled solution at either high (high label, HL) or low (low label, LL) (13)CO2 concentrations. The uptake of the (13)CO2 label served as a proxy for the internal transport of respired CO2, whilst the transpiration rate was manipulated at the leaf level by altering the vapour pressure deficit (VPD) of the air. Simultaneously, leaf gas exchange was measured, allowing comparison of internal CO2 assimilation with that assimilated from the atmosphere. Subsequent (13)C analysis of branch and leaf tissues revealed that woody tissues assimilated more label under high VPD, corresponding to higher transpiration, than under low VPD. More (13)C was assimilated in leaf tissue than in woody tissue under the HL treatment, whereas more (13)C was assimilated in woody tissue than in leaf tissue under the LL treatment. The ratio of (13)CO2 assimilated from the internal source to CO2 assimilated from the atmosphere was highest for the branches under the HL and high VPD treatment, but was relatively small regardless of VPD×label treatment combination (up to 1.9%). These results showed that assimilation of internal CO2 is highly dependent on the rate of transpiration and xylem sap [CO2]. Therefore, it can be expected that the relative contribution of internal CO2 recycling to tree carbon gain is strongly dependent on factors controlling transpiration, respiration, and photosynthesis.
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Affiliation(s)
- Jasper Bloemen
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Gent, Belgium.
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23
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Etzold S, Zweifel R, Ruehr NK, Eugster W, Buchmann N. Long-term stem CO2 concentration measurements in Norway spruce in relation to biotic and abiotic factors. THE NEW PHYTOLOGIST 2013; 197:1173-1184. [PMID: 23316716 DOI: 10.1111/nph.12115] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 11/26/2012] [Indexed: 06/01/2023]
Abstract
Stem CO(2) concentrations (stem [CO(2)]) undergo large temporal variations that need to be understood to better link tree physiological processes to biosphere-atmosphere CO(2) exchange. During 19 months, stem [CO(2)] was continuously measured in mature subalpine Norway spruce trees (Picea abies) and jointly analysed with stem, soil and air temperatures, sap flow rates, stem radius changes and CO(2) efflux rates from stem and soil on different time scales. Stem [CO(2)] exhibited a strong seasonality, of which over 80% could be explained with stem and soil temperatures. Both physical equilibrium processes of CO(2) between water and air according to Henry's law as well as physiological effects, including sap flow and local respiration, concurrently contributed to these temporal variations. Moreover, the explanatory power of potential biological drivers (stem radius changes, sap flow and soil respiration) varied strongly with season and temporal resolution. We conclude that seasonal and daily courses of stem [CO(2)] in spruce trees are a combined effect of physical equilibrium and tree physiological processes. Furthermore, we emphasize the relevance of axial diffusion of CO(2) along air-filled spaces in the wood, and potential wound response processes owing to sensor installation.
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Affiliation(s)
- Sophia Etzold
- Swiss Federal Research Institute WSL, Zuercherstrasse 111, 8903, Birmensdorf, Switzerland
| | - Roman Zweifel
- Swiss Federal Research Institute WSL, Zuercherstrasse 111, 8903, Birmensdorf, Switzerland
| | - Nadine K Ruehr
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), 82467, Garmisch-Partenkirchen, Germany
| | - Werner Eugster
- ETH Zurich, Institute of Agricultural Sciences, Universitaetsstrasse 2, 8092, Zurich, Switzerland
| | - Nina Buchmann
- ETH Zurich, Institute of Agricultural Sciences, Universitaetsstrasse 2, 8092, Zurich, Switzerland
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24
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Ubierna N, Kumar AS, Cernusak LA, Pangle RE, Gag PJ, Marshall JD. Storage and transpiration have negligible effects on delta13C of stem CO2 efflux in large conifer trees. TREE PHYSIOLOGY 2009; 29:1563-1574. [PMID: 19840994 DOI: 10.1093/treephys/tpp089] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Stem respiration rates are often quantified by measuring the CO(2) efflux from stems into chambers. It has been suggested that these measurements underestimate respiration because some of the respired CO(2) can be either retained or transported upwards in the transpiration stream. If the stem CO(2) efflux does not represent all respired CO(2), then the interpretation of its isotopic signal may be compromised as well. The C-isotope composition of the respired CO(2) and the measured efflux could differ due to (i) the release of CO(2) produced elsewhere into the stem and transported upwards in xylem water (soil CO(2) or root respired CO(2)); (ii) the retention or release of CO(2) storage pools within the tree stem and (iii) the removal of CO(2) by the transpiration stream. We investigated the effects of these processes in large conifer trees using two manipulative experiments: a labelling experiment and a crown removal experiment. The labelling experiment used an extreme enrichment of dissolved CO(2) in soil water to assess the C uptake by the roots. In this experiment, we found no contamination of the stem CO(2) pool despite clear evidence that the water itself had been taken up. The crown removal experiment tested for vertical CO(2) flux in xylem water by eliminating transpiration. Here, we found no change in the delta(13)C of stem CO(2) efflux (delta(EA); P > 0.05). We concluded that for these large conifers, sap-flow influenced neither delta(13)C of stem efflux nor that of the stem CO(2) pool. By parameterizing Henry's Law for conditions inside the stem, we estimated the transport flux to represent 1-3% of the stem CO(2) efflux to the atmosphere. Finally, assuming a 2 per thousand difference between delta(13)C of root and stem respiration, we estimated that potential contamination of delta(EA) by root respired CO(2) would be < 0.1 per thousand. Thus, neither the release of soil or root CO(2), nor storage in the stem, nor vertical transport of CO(2) in the xylem sap had any detectable influence on delta(13)C of the CO(2) measured in stem efflux.
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Affiliation(s)
- Nerea Ubierna
- Department of Forest Resources, University of Idaho, Moscow, ID 83844-1133, USA.
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25
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Abstract
It is known that stem CO2 efflux differs somewhat both temporally and spatially from actual stem respiration, but relations between these two are not fully understood. A physical model of CO2 diffusion and advection by xylem sap flow is developed to interpret the CO2 flux signal from the stem. Model predictions are compared against measured CO2 efflux data from a field-grown 16-m Pinus sylvestris L. tree. The ratio of CO2 efflux to CO2 production is predicted to be much larger in the upper part of the tree than in the lower part as the xylem sap carries the respired CO2 upwards. The model also predicts the temperature dependency of real respiration to be higher than that of the CO2 efflux due to the slowness of diffusion. The relation between stem respiration and CO2 efflux depends strongly on the sap flow rate, radial diffusion resistance and stem geometry and size. The model may be used to scale individual CO2 efflux measurements to evaluate the respiration rate of whole trees and forests.
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Affiliation(s)
- Teemu Hölttä
- Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014, Finland.
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26
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Eyles A, Pinkard EA, O'Grady AP, Worledge D, Warren CR. Role of corticular photosynthesis following defoliation in Eucalyptus globulus. PLANT, CELL & ENVIRONMENT 2009; 32:1004-14. [PMID: 19344333 DOI: 10.1111/j.1365-3040.2009.01984.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Defoliation can reduce net fixation of atmospheric CO(2) by the canopy, but increase the intensity and duration of photosynthetically active radiation on stems. Stem CO(2) flux and leaf gas exchange in young Eucalyptus globulus seedlings were measured to assess the impact of defoliation on these processes and to determine the potential contribution of re-fixation by photosynthetic inner bark in offsetting the effects of defoliation in a woody species. Pot and field trials examined how artificial defoliation of the canopy affected the photosynthetic characteristics of main stems of young Eucalyptus globulus seedlings. Defoliated potted seedlings were characterized by transient increases in foliar photosynthetic rates and concomitant decreases in stem CO(2) fluxes (both in the dark and light). Defoliated field-grown seedlings showed similar stem CO(2) flux responses, but of reduced magnitude. Despite demonstrating increased re-fixation capability, defoliated potted-seedlings had slowed stem growth. The green stem of seedlings exhibited largely shade-adapted characteristics. Defoliation reduced stem chlorophyll a/b ratio and increased carotenoid concentration. An increased capacity to re-fix internally respired CO(2) (up to 96%) suggested that stem re-fixation represents a previously unexplored mechanism to minimize the impact of foliar loss by maximizing the contribution of all photosynthetic tissues, particularly for young seedlings.
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Affiliation(s)
- Alieta Eyles
- Cooperative Research Centre for Forestry, Private Bag 12, Hobart, Tas. 7001, Australia.
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27
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Gruber A, Wieser G, Oberhuber W. Intra-annual dynamics of stem CO2 efflux in relation to cambial activity and xylem development in Pinus cembra. TREE PHYSIOLOGY 2009; 29:641-9. [PMID: 19203979 PMCID: PMC3013296 DOI: 10.1093/treephys/tpp001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The relationship between stem CO(2) efflux (E(S)), cambial activity and xylem production in Pinus cembra L. was determined at the timberline (1950 m a.s.l.) of the Central Austrian Alps, for 1 year. The E(S) was measured continuously from June 2006 to August 2007 using an infrared gas-analysis system. Cambial activity and xylem production were determined by repeated microcore sampling of the developing tree ring, and radial increment was monitored using automated point dendrometers. Besides temperature, the number of living tracheids and cambial cells was predominantly responsible for E(S), and E(S) normalized to 10 degrees C (E(S10)) was significantly correlated to the number of living cells throughout the year (r(2) = 0.574; P < 0.001). However, elevated E(S) and missing correlation between E(S10) and xylem production were detected during cambial reactivation in April and during transition from active phase to rest, which occurred in August and lasted until early September. Results of this study indicate that (i) during seasonal variations in cambial activity, nonlinearity between E(S) and xylem production occurs and (ii) elevated metabolic activity during transition stages in the cambial active-dormancy cycle influences the carbon budget of P. cembra. Daily radial stem increment was primarily influenced by the number of enlarging cells and was not correlated to E(S).
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Affiliation(s)
- A Gruber
- Institute of Botany, University of Innsbruck, 6020 Innsbruck, Austria
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28
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McGuire MA, Marshall JD, Teskey RO. Assimilation of xylem-transported 13C-labelled CO2 in leaves and branches of sycamore (Platanus occidentalis L.). JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:3809-17. [PMID: 19602545 PMCID: PMC2736895 DOI: 10.1093/jxb/erp222] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Previous reports have shown that CO(2) dissolved in xylem sap in tree stems can move upward in the transpiration stream. To determine the fate of this dissolved CO(2), the internal transport of respired CO(2) at high concentration from the bole of the tree was simulated by allowing detached young branches of sycamore (Platanus occidentalis L.) to transpire water enriched with a known quantity of (13)CO(2) in sunlight. Simultaneously, leaf net photosynthesis and CO(2) efflux from woody tissue were measured. Branch and leaf tissues were subsequently analysed for (13)C content to determine the quantity of transported (13)CO(2) label that was fixed. Treatment branches assimilated an average of 35% (SE=2.4) of the (13)CO(2) label taken up in the treatment water. The majority was fixed in the woody tissue of the branches, with smaller amounts fixed in the leaves and petioles. Overall, the fixation of internally transported (13)CO(2) label by woody tissues averaged 6% of the assimilation of CO(2) from the atmosphere by the leaves. Woody tissue assimilation rates calculated from measurements of (13)C differed from rates calculated from measurements of CO(2) efflux in the lower branch but not in the upper branch. The results of this study showed unequivocally that CO(2) transported in xylem sap can be fixed in photosynthetic cells in the leaves and branches of sycamore trees and provided evidence that recycling of xylem-transported CO(2) may be an important means by which trees reduce the carbon cost of respiration.
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Affiliation(s)
- M A McGuire
- School of Forestry and Natural Resources, University of Georgia, Athens, Georgia 30602, USA.
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29
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Cerasoli S, McGuire MA, Faria J, Mourato M, Schmidt M, Pereira JS, Chaves MM, Teskey RO. CO2 efflux, CO2 concentration and photosynthetic refixation in stems of Eucalyptus globulus (Labill.). JOURNAL OF EXPERIMENTAL BOTANY 2008; 60:99-105. [PMID: 19036840 DOI: 10.1093/jxb/ern272] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In spite of the importance of respiration in forest carbon budgets, the mechanisms by which physiological factors control stem respiration are unclear. An experiment was set up in a Eucalyptus globulus plantation in central Portugal with monoculture stands of 5-year-old and 10-year-old trees. CO(2) efflux from stems under shaded and unshaded conditions, as well as the concentration of CO(2) dissolved in sap [CO(2)(*)], stem temperature, and sap flow were measured with the objective of improving our understanding of the factors controlling CO(2) release from stems of E. globulus. CO(2) efflux was consistently higher in 5-year-old, compared with 10-year-old, stems, averaging 3.4 versus 1.3 mumol m(-2) s(-1), respectively. Temperature and [CO(2)(*)] both had important, and similar, influences on the rate of CO(2) efflux from the stems, but neither explained the difference in the magnitude of CO(2) efflux between trees of different age and size. No relationship was found between efflux and sap flow, and efflux was independent of tree volume, suggesting the presence of substantial barriers to the diffusion of CO(2) from the xylem to the atmosphere in this species. The rate of corticular photosynthesis was the same in trees of both ages and only reduced CO(2) efflux by 7%, probably due to the low irradiance at the stem surface below the canopy. The younger trees were growing at a much faster rate than the older trees. The difference between CO(2) efflux from the younger and older stems appears to have resulted from a difference in growth respiration rather than a difference in the rate of diffusion of xylem-transported CO(2).
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Affiliation(s)
- S Cerasoli
- Departamento de Egenharia Floresta, Instituto Superior de Agronomia, Universidade Técnica de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
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30
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Teskey RO, Saveyn A, Steppe K, McGuire MA. Origin, fate and significance of CO2 in tree stems. THE NEW PHYTOLOGIST 2007; 177:17-32. [PMID: 18028298 DOI: 10.1111/j.1469-8137.2007.02286.x] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Although some CO(2) released by respiring cells in tree stems diffuses directly to the atmosphere, on a daily basis 15-55% can remain within the tree. High concentrations of CO(2) build up in stems because of barriers to diffusion in the inner bark and xylem. In contrast with atmospheric [CO(2)] of c. 0.04%, the [CO(2)] in tree stems is often between 3 and 10%, and sometimes exceeds 20%. The [CO(2)] in stems varies diurnally and seasonally. Some respired CO(2) remaining in the stem dissolves in xylem sap and is transported toward the leaves. A portion can be fixed by photosynthetic cells in woody tissues, and a portion diffuses out of the stem into the atmosphere remote from the site of origin. It is now evident that measurements of CO(2) efflux to the atmosphere, which have been commonly used to estimate the rate of woody tissue respiration, do not adequately account for the internal fluxes of CO(2). New approaches to quantify both internal and external fluxes of CO(2) have been developed to estimate the rate of woody tissue respiration. A more complete assessment of internal fluxes of CO(2) in stems will improve our understanding of the carbon balance of trees.
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Affiliation(s)
- Robert O Teskey
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
| | - An Saveyn
- Laboratory of Plant Ecology, Ghent University, Gent, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Ghent University, Gent, Belgium
| | - Mary Anne McGuire
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
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31
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Saveyn A, Steppe K, McGuire MA, Lemeur R, Teskey RO. Stem respiration and carbon dioxide efflux of young Populus deltoides trees in relation to temperature and xylem carbon dioxide concentration. Oecologia 2007; 154:637-49. [PMID: 17957386 DOI: 10.1007/s00442-007-0868-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Accepted: 09/24/2007] [Indexed: 10/22/2022]
Abstract
Oxidative respiration is strongly temperature driven. However, in woody stems, efflux of CO(2) to the atmosphere (E (A)), commonly used to estimate the rate of respiration (R (S)), and stem temperature (T (st)) have often been poorly correlated, which we hypothesized was due to transport of respired CO(2) in xylem sap, especially under high rates of sap flow (f (s)). To test this, we measured E (A), T (st), f (s) and xylem sap CO(2) concentrations ([CO(2)*]) in 3-year-old Populus deltoides trees under different weather conditions (sunny and rainy days) in autumn. We also calculated R (S) by mass balance as the sum of both outward and internal CO(2) fluxes and hypothesized that R (S) would correlate better with T (st) than E (A). We found that E (A) sometimes correlated well with T (st), but not on sunny mornings and afternoons or on rainy days. When the temperature effect on E (A) was accounted for, a clear positive relationship between E (A) and xylem [CO(2)*] was found. [CO(2)*] varied diurnally and increased substantially at night and during periods of rain. Changes in [CO(2)*] were related to changes in f (s) but not T (st). We conclude that changes in both respiration and internal CO(2) transport altered E (A). The dominant component flux of R (S) was E (A). However, on a 24-h basis, the internal transport flux represented 9-18% and 3-7% of R (S) on sunny and rainy days, respectively, indicating that the contribution of stem respiration to forest C balance may be larger than previously estimated based on E (A) measurements. Unexpectedly, the relationship between R (S) and T (st) was sometimes weak in two of the three trees. We conclude that in addition to temperature, other factors such as water deficits or substrate availability exert control on the rate of stem respiration so that simple temperature functions are not sufficient to predict stem respiration.
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Affiliation(s)
- An Saveyn
- Laboratory of Plant Ecology, Ghent University, Coupure Links 653, 9000, Gent, Belgium.
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32
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Steppe K, Saveyn A, McGuire MA, Lemeur R, Teskey RO. Resistance to radial CO 2 diffusion contributes to between-tree variation in CO 2 efflux of Populus deltoides stems. FUNCTIONAL PLANT BIOLOGY : FPB 2007; 34:785-792. [PMID: 32689406 DOI: 10.1071/fp07077] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Accepted: 06/14/2007] [Indexed: 06/11/2023]
Abstract
Rates of CO2 efflux of stems and branches are highly variable among and within trees and across stands. Scaling factors have only partially succeeded in accounting for the observed variations. In this study, the resistance to radial CO2 diffusion was quantified for tree stems of an eastern cottonwood (Populus deltoides Bartr. ex Marsh.) clone by direct manipulation of the CO2 concentration ([CO2]) of xylem sap under controlled conditions. Tree-specific linear relationships between rates of stem CO2 efflux (JO) and xylem [CO2] were found. The resistance to radial CO2 diffusion differed 6-fold among the trees and influenced the balance between the amount of CO2 retained in the xylem v. that which diffused to the atmosphere. Therefore, we hypothesised that variability in the resistance to radial CO2 diffusion might be an overlooked cause for the inconsistencies and large variations in woody tissue CO2 efflux. It was found that transition from light to dark conditions caused a rapid increase in JO and xylem [CO2], both in manipulated trees and in an intact tree with no sap manipulation. This resulted in an increased resistance to radial CO2 diffusion during the dark, at least for trees with smaller daytime resistances. Stem diameter changes measured in the intact tree supported the idea that higher actual respiration rates occurred at night owing to higher metabolism in relation to an improved water status and higher turgor pressure.
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Affiliation(s)
- Kathy Steppe
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium
| | - An Saveyn
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium
| | - Mary Anne McGuire
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
| | - Raoul Lemeur
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium
| | - Robert O Teskey
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
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