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Drake JE, Vårhammar A, Aspinwall MJ, Pfautsch S, Ghannoum O, Tissue DT, Tjoelker MG. Pushing the envelope: do narrowly and widely distributed Eucalyptus species differ in response to climate warming? THE NEW PHYTOLOGIST 2024; 243:82-97. [PMID: 38666344 DOI: 10.1111/nph.19774] [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: 10/03/2023] [Accepted: 03/29/2024] [Indexed: 06/07/2024]
Abstract
Contemporary climate change will push many tree species into conditions that are outside their current climate envelopes. Using the Eucalyptus genus as a model, we addressed whether species with narrower geographical distributions show constrained ability to cope with warming relative to species with wider distributions, and whether this ability differs among species from tropical and temperate climates. We grew seedlings of widely and narrowly distributed Eucalyptus species from temperate and tropical Australia in a glasshouse under two temperature regimes: the summer temperature at seed origin and +3.5°C. We measured physical traits and leaf-level gas exchange to assess warming influences on growth rates, allocation patterns, and physiological acclimation capacity. Warming generally stimulated growth, such that higher relative growth rates early in development placed seedlings on a trajectory of greater mass accumulation. The growth enhancement under warming was larger among widely than narrowly distributed species and among temperate rather than tropical provenances. The differential growth enhancement was primarily attributable to leaf area production and adjustments of specific leaf area. Our results suggest that tree species, including those with climate envelopes that will be exceeded by contemporary climate warming, possess capacity to physiologically acclimate but may have varying ability to adjust morphology.
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Affiliation(s)
- John E Drake
- Department of Sustainable Resources Management, College of Environmental Science and Forestry, State University of New York, 1 Forestry Drive, Syracuse, NY, 13210, USA
| | - Angelica Vårhammar
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | | | - Sebastian Pfautsch
- Urban Transformations Research Centre, Western Sydney University, Locked Bag 1797, Penrith, 2751, NSW, Australia
| | - Oula Ghannoum
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Mark G Tjoelker
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
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2
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Speckert TC, Petibon F, Wiesenberg GLB. Late-season biosynthesis of leaf fatty acids and n-alkanes of a mature beech ( Fagus sylvatica) tree traced via 13CO 2 pulse-chase labelling and compound-specific isotope analysis. FRONTIERS IN PLANT SCIENCE 2023; 13:1029026. [PMID: 36684794 PMCID: PMC9853289 DOI: 10.3389/fpls.2022.1029026] [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: 08/26/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Leaf cuticular waxes play an important role in reducing evapotranspiration via diffusion. However, the ability of mature trees to regulate the biosynthesis of waxes to changing conditions (e.g., drought, light exposition) remain an open question, especially during the late growing season. This holds also true for one of the most widely distributed trees in Central Europe, the European beech tree (Fagus sylvatica L.). In order to investigate the ongoing formation of wax constituents like alkanes and fatty acids, we conducted a 13CO2 pulse-chase labelling experiment on sun-exposed and shaded branches of a mature beech tree during the late summer 2018. The 13C-label was traced via compound-specific δ13C isotope analysis of n-alkanes and fatty acids to determine the de-novo biosynthesis within these compound classes. We did not observe a significant change in lipid concentrations during the late growing season, but we found higher n-alkane concentrations in sun-exposed compared to shaded leaves in August and September. The n-alkane and fatty acid composition showed ongoing modifications during the late growing season. Together with the uptake and following subsequent decrease of the 13C-label, this suggests ongoing de-novo biosynthesis, especially of fatty acids in European beech leaves. Moreover, there is a high variability in the 13C-label among individual branches and between sun-exposed and shaded leaves. At the same time, sun-exposed leaves invest more of the assimilated C into secondary metabolites such as lipids than shaded leaves. This indicates that the investigated mature beech tree could adjust its lipid production and composition in order to acclimate to changes in microclimates within the tree crown and during the investigated period.
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3
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Hikino K, Danzberger J, Riedel VP, Hesse BD, Hafner BD, Gebhardt T, Rehschuh R, Ruehr NK, Brunn M, Bauerle TL, Landhäusser SM, Lehmann MM, Rötzer T, Pretzsch H, Buegger F, Weikl F, Pritsch K, Grams TEE. Dynamics of initial carbon allocation after drought release in mature Norway spruce-Increased belowground allocation of current photoassimilates covers only half of the carbon used for fine-root growth. GLOBAL CHANGE BIOLOGY 2022; 28:6889-6905. [PMID: 36039835 DOI: 10.1111/gcb.16388] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 07/02/2022] [Indexed: 06/15/2023]
Abstract
After drought events, tree recovery depends on sufficient carbon (C) allocation to the sink organs. The present study aimed to elucidate dynamics of tree-level C sink activity and allocation of recent photoassimilates (Cnew ) and stored C in c. 70-year-old Norway spruce (Picea abies) trees during a 4-week period after drought release. We conducted a continuous, whole-tree 13 C labeling in parallel with controlled watering after 5 years of experimental summer drought. The fate of Cnew to growth and CO2 efflux was tracked along branches, stems, coarse- and fine roots, ectomycorrhizae and root exudates to soil CO2 efflux after drought release. Compared with control trees, drought recovering trees showed an overall 6% lower C sink activity and 19% less allocation of Cnew to aboveground sinks, indicating a low priority for aboveground sinks during recovery. In contrast, fine-root growth in recovering trees was seven times greater than that of controls. However, only half of the C used for new fine-root growth was comprised of Cnew while the other half was supplied by stored C. For drought recovery of mature spruce trees, in addition to Cnew , stored C appears to be critical for the regeneration of the fine-root system and the associated water uptake capacity.
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Affiliation(s)
- Kyohsuke Hikino
- Professorship for Land Surface-Atmosphere Interactions, Ecophysiology of Plants, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Jasmin Danzberger
- Institute of Biochemical Plant Pathology, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - Vincent P Riedel
- Professorship for Land Surface-Atmosphere Interactions, Ecophysiology of Plants, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Benjamin D Hesse
- Professorship for Land Surface-Atmosphere Interactions, Ecophysiology of Plants, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Benjamin D Hafner
- School of Integrative Plant Science, Cornell University, Ithaca, New York, USA
| | - Timo Gebhardt
- Professorship for Land Surface-Atmosphere Interactions, Ecophysiology of Plants, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Romy Rehschuh
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research-Atmospheric Environmental Research (KIT/IMK-IFU), Garmisch-Partenkirchen, Germany
- Institute of General Ecology and Environmental Protection, Technische Universität Dresden, Pienner Str. 7, Tharandt, 01737, Germany
| | - Nadine K Ruehr
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research-Atmospheric Environmental Research (KIT/IMK-IFU), Garmisch-Partenkirchen, Germany
| | - Melanie Brunn
- Institute for Environmental Sciences, University Koblenz-Landau, Landau, Germany
| | - Taryn L Bauerle
- School of Integrative Plant Science, Cornell University, Ithaca, New York, USA
| | - Simon M Landhäusser
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
| | - Marco M Lehmann
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Forest Dynamics, Birmensdorf, Switzerland
| | - Thomas Rötzer
- Forest Growth and Yield Science, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Hans Pretzsch
- Forest Growth and Yield Science, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Franz Buegger
- Institute of Biochemical Plant Pathology, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - Fabian Weikl
- Professorship for Land Surface-Atmosphere Interactions, Ecophysiology of Plants, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
- Institute of Biochemical Plant Pathology, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - Karin Pritsch
- Institute of Biochemical Plant Pathology, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - Thorsten E E Grams
- Professorship for Land Surface-Atmosphere Interactions, Ecophysiology of Plants, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
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4
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Cong Y, Saurer M, Bai E, Siegwolf R, Gessler A, Liu K, Han H, Dang Y, Xu W, He HS, Li MH. In situ 13CO2 labeling reveals that alpine treeline trees allocate less photoassimilates to roots compared with low-elevation trees. TREE PHYSIOLOGY 2022; 42:1943-1956. [PMID: 35535565 DOI: 10.1093/treephys/tpac048] [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: 10/18/2021] [Accepted: 04/13/2022] [Indexed: 06/14/2023]
Abstract
Carbon (C) allocation plays a crucial role for survival and growth of alpine treeline trees, however it is still poorly understood. Using in situ 13CO2 labeling, we investigated the leaf photosynthesis and the allocation of 13C labeled photoassimilates in various tissues (leaves, twigs and fine roots) in treeline trees and low-elevation trees. Non-structural carbohydrate concentrations were also determined. The alpine treeline trees (2000 m. a.s.l.), compared with low-elevation trees (1700 m a.s.l.), did not show any disadvantage in photosynthesis, but the former allocated proportionally less newly assimilated C belowground than the latter. Carbon residence time in leaves was longer in treeline trees (19 days) than that in low-elevation ones (10 days). We found an overall lower density of newly assimilated C in treeline trees. The alpine treeline trees may have a photosynthetic compensatory mechanism to counteract the negative effects of the harsh treeline environment (e.g., lower temperature and shorter growing season) on C gain. Lower temperature at treeline may limit the sink activity and C downward transport via phloem, and shorter treeline growing season may result in early cessation of root growth, decreases sink strength, which all together lead to lower density of new C in the sink tissues and finally limit the growth of the alpine treeline trees.
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Affiliation(s)
- Yu Cong
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, 5268 Renmin Street, Nanguan District, Changchun 130024, China
- Northeast Institute of Geography and Agricultural Ecology, Chinese Academy of Sciences, 4888 Shengbei Street, Kuancheng District, Changchun 130102, China
| | - Matthias Saurer
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse111, Birmensdorf CH-8903, Switzerland
| | - Edith Bai
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, 5268 Renmin Street, Nanguan District, Changchun 130024, China
| | - Rolf Siegwolf
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse111, Birmensdorf CH-8903, Switzerland
| | - Arthur Gessler
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse111, Birmensdorf CH-8903, Switzerland
- Institute of Terrestrial Ecosystems, ETH Zurich, Universitaetsstrasse 16, Zurich 8092, Switzerland
| | - Kai Liu
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, 5268 Renmin Street, Nanguan District, Changchun 130024, China
| | - Hudong Han
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, 5268 Renmin Street, Nanguan District, Changchun 130024, China
| | - Yongcai Dang
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, 5268 Renmin Street, Nanguan District, Changchun 130024, China
| | - Wenhua Xu
- Institute of Agricultural Resource and Environment, Jilin Academy of Agricultural Sciences, 1363 Shengtai Street, Nanguan District, Changchun 130033, China
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenhe District, Shenyang 110016, China
| | - Hong S He
- School of Natural Resources, University of Missouri, Columbia, MO 65211, USA
| | - Mai-He Li
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, 5268 Renmin Street, Nanguan District, Changchun 130024, China
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse111, Birmensdorf CH-8903, Switzerland
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5
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Needham JF, Arellano G, Davies SJ, Fisher RA, Hammer V, Knox RG, Mitre D, Muller-Landau HC, Zuleta D, Koven CD. Tree crown damage and its effects on forest carbon cycling in a tropical forest. GLOBAL CHANGE BIOLOGY 2022; 28:5560-5574. [PMID: 35748712 DOI: 10.1111/gcb.16318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Abstract
Crown damage can account for over 23% of canopy biomass turnover in tropical forests and is a strong predictor of tree mortality; yet, it is not typically represented in vegetation models. We incorporate crown damage into the Functionally Assembled Terrestrial Ecosystem Simulator (FATES), to evaluate how lags between damage and tree recovery or death alter demographic rates and patterns of carbon turnover. We represent crown damage as a reduction in a tree's crown area and leaf and branch biomass, and allow associated variation in the ratio of aboveground to belowground plant tissue. We compare simulations with crown damage to simulations with equivalent instant increases in mortality and benchmark results against data from Barro Colorado Island (BCI), Panama. In FATES, crown damage causes decreases in growth rates that match observations from BCI. Crown damage leads to increases in carbon starvation mortality in FATES, but only in configurations with high root respiration and decreases in carbon storage following damage. Crown damage also alters competitive dynamics, as plant functional types that can recover from crown damage outcompete those that cannot. This is a first exploration of the trade-off between the additional complexity of the novel crown damage module and improved predictive capabilities. At BCI, a tropical forest that does not experience high levels of disturbance, both the crown damage simulations and simulations with equivalent increases in mortality does a reasonable job of capturing observations. The crown damage module provides functionality for exploring dynamics in forests with more extreme disturbances such as cyclones and for capturing the synergistic effects of disturbances that overlap in space and time.
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Affiliation(s)
- Jessica F Needham
- Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Gabriel Arellano
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, USA
- Oikobit LLC, Albuquerque, New Mexico, USA
| | - Stuart J Davies
- Forest Global Earth Observatory, Smithsonian Tropical Research Institute, Washington, District of Columbia, USA
| | - Rosie A Fisher
- CICERO Center for International Climate Research, Oslo, Norway
| | - Valerie Hammer
- University of California, Berkeley, Berkeley, California, USA
| | - Ryan G Knox
- Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - David Mitre
- Smithsonian Tropical Research Institute, Apartado, Repu ́blica de Panamá
| | | | - Daniel Zuleta
- Forest Global Earth Observatory, Smithsonian Tropical Research Institute, Washington, District of Columbia, USA
| | - Charlie D Koven
- Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, California, USA
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6
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Rehschuh R, Ruehr NK. Diverging responses of water and carbon relations during and after heat and hot drought stress in Pinus sylvestris. TREE PHYSIOLOGY 2022; 42:1532-1548. [PMID: 34740258 PMCID: PMC9366868 DOI: 10.1093/treephys/tpab141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Accepted: 10/22/2021] [Indexed: 06/13/2023]
Abstract
Forests are increasingly affected by heatwaves, often co-occurring with drought, with consequences for water and carbon (C) cycling. However, our ability to project tree resilience to more intense hot droughts remains limited. Here, we used single tree chambers (n = 18) to investigate transpiration (E), net assimilation (Anet), root respiration (Rroot) and stem diameter change in Scots pine seedlings in a control treatment and during gradually intensifying heat or drought-heat stress (max. 42 °C), including recovery. Alongside this, we assessed indicators of stress impacts and recovery capacities. In the heat treatment, excessive leaf heating was mitigated via increased E, while under drought-heat, E ceased and leaf temperatures reached 46 °C. However, leaf electrolyte leakage was negligible, while light-adapted quantum yield of photosystem II (F'v/F'm) declined alongside Anet moderately in heat, but strongly in drought-heat seedlings, in which respiration exceeded C uptake. Drought-heat largely affected the hydraulic system as apparent in stem diameter shrinkage, declining relative needle water content (RWCNeedle) and water potential (ΨNeedle) reaching -2.7 MPa, alongside a 90% decline of leaf hydraulic conductance (KLeaf). Heat alone resulted in low functional impairment and all measured parameters recovered quickly. Contrary, following drought-heat, the recovery of KLeaf was incomplete and stem hydraulic conductivity (KS) was 25% lower than the control. However, F'v/F'm recovered and the tree net C balance reached control values 2 days post-stress, with stem increment rates accelerating during the second recovery week. This indicates a new equilibrium of C uptake and release in drought-heat seedlings independent of hydraulic impairment, which may slowly contribute to the repair of damaged tissues. In summary, Scots pine recovered rapidly following moderate heat stress, while combined with drought, hydraulic and thermal stress intensified, resulting in functional damage and slow recovery of hydraulic conductance. This incomplete hydraulic recovery could critically limit evaporative cooling capacities and C uptake under repeated heatwaves.
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Affiliation(s)
| | - Nadine K Ruehr
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research-Atmospheric Environmental Research (KIT/IMK-IFU), Kreuzeckbahnstraße 19, 82467 Garmisch-Partenkirchen, Germany
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7
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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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8
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Fernández de Simón B, Cadahía E, Aranda I. Aerial and underground organs display specific metabolic strategies to cope with water stress under rising atmospheric CO 2 in Fagus sylvatica L. PHYSIOLOGIA PLANTARUM 2022; 174:e13711. [PMID: 35570621 PMCID: PMC9321914 DOI: 10.1111/ppl.13711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 04/26/2022] [Indexed: 06/15/2023]
Abstract
Beech is known to be a moderately drought-sensitive tree species, and future increases in atmospheric concentrations of CO2 ([CO2 ]) could influence its ecological interactions, also with changes at the metabolic level. The metabolome of leaves and roots of drought-stressed beech seedlings grown under two different [CO2 ] (400 (aCO2 ) and 800 (eCO2 ) ppm) was analyzed together with gas exchange parameters and water status. Water stress estimated from predawn leaf water potential (Ψpd ) was similar under both [CO2 ], although eCO2 had a positive impact on net photosynthesis and intrinsic water use efficiency. The aerial and underground organs showed different metabolomes. Leaves mainly stored C metabolites, while those of N and P accumulated differentially in roots. Drought triggered the proline and N-rich amino acids biosynthesis in roots through the activation of arginine and proline pathways. Besides the TCA cycle, polyols and soluble sugar biosynthesis were activated in roots, with no clear pattern seen in the leaves, prioritizing the root functioning as metabolites sink. eCO2 slightly altered this metabolic acclimation to drought, reflecting mitigation of its effect. The leaves showed only minor changes, investing C surplus in secondary metabolites and malic acid. The TCA cycle metabolites and osmotically active substances increased in roots, but many other metabolites decreased as if the water stress was dampened. Above- and belowground plant metabolomes were differentially affected by two drivers of climate change, water scarcity and high [CO2 ], showing different chemical responsiveness that could modulate the tree adaptation to future climatic scenarios.
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Affiliation(s)
- Brígida Fernández de Simón
- Grupo de Ecología Funcional de Especies ForestalesCentro de Investigacion Forestal (CIFOR‐INIA) CSICMadridSpain
| | - Estrella Cadahía
- Grupo de Ecología Funcional de Especies ForestalesCentro de Investigacion Forestal (CIFOR‐INIA) CSICMadridSpain
| | - Ismael Aranda
- Grupo de Ecología Funcional de Especies ForestalesCentro de Investigacion Forestal (CIFOR‐INIA) CSICMadridSpain
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9
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Tsuji C, Dannoura M, Desalme D, Angeli N, Takanashi S, Kominami Y, Epron D. Drought affects the fate of non-structural carbohydrates in hinoki cypress. TREE PHYSIOLOGY 2022; 42:784-796. [PMID: 34635913 DOI: 10.1093/treephys/tpab135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 10/01/2021] [Indexed: 06/13/2023]
Abstract
Tree species that close stomata early in response to drought are likely to suffer from an imbalance between limited carbohydrate supply due to reduced photosynthesis and metabolic demand. Our objective was to clarify the dynamic responses of non-structural carbohydrates to drought in a water-saving species, the hinoki cypress (Chamaecyparis obtusa Sieb. et Zucc.). To this end, we pulse-labeled young trees with 13CO2 10 days after the beginning of the drought treatment. Trees were harvested 7 days later, early during drought progression, and 86 days later when they had suffered from a long and severe drought. The labeled carbon (C) was traced in phloem extract, in the organic matter and starch of all the organs, and in the soluble sugars (sucrose, glucose and fructose) of the most metabolically active organs (foliage, green branches and fine roots). No drought-related changes in labeled C partitioning between belowground and aboveground organs were observed. The C allocation between non-structural carbohydrates was altered early during drought progression: starch concentration was lower by half in the photosynthetic organs, while the concentration of almost all soluble sugars tended to increase. The preferential allocation of labeled C to glucose and fructose reflected an increased demand for soluble sugars for osmotic adjustment. After 3 months of a lethal drought, the concentrations of soluble sugars and starch were admittedly lower in drought-stressed trees than in the controls, but the pool of non-structural carbohydrates was far from completely depleted. However, the allocation to storage had been impaired by drought; photosynthesis and the sugar translocation rate had also been reduced by drought. Failure to maintain cell turgor through osmoregulation and to refill embolized xylem due to the depletion in soluble sugars in the roots could have resulted in tree mortality in hinoki cypress, though the total pool of carbohydrate was not completely depleted.
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Affiliation(s)
- Chiaki Tsuji
- Graduate School of Environmental Studies, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501, Japan
| | - Masako Dannoura
- Graduate School of Environmental Studies, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501, Japan
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Dorine Desalme
- Université de Lorraine, AgroParisTech, INRAE, UMR Silva, 34 cours Léopold, Nancy F-54000, France
| | - Nicolas Angeli
- Université de Lorraine, AgroParisTech, INRAE, UMR Silva, 34 cours Léopold, Nancy F-54000, France
| | - Satoru Takanashi
- Forestry and Forest Products Research Institute, Kansai Research Centre, 68 Nagaikyutaroh, Momoyama, Fushimi, Kyoto 612-0855, Japan
| | - Yuji Kominami
- Forestry and Forest Products Research Institute, 1 Matsunosato, Ibaraki, Tsukuba 305-8687, Japan
| | - Daniel Epron
- Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
- Université de Lorraine, AgroParisTech, INRAE, UMR Silva, 34 cours Léopold, Nancy F-54000, France
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10
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Rehschuh R, Rehschuh S, Gast A, Jakab AL, Lehmann MM, Saurer M, Gessler A, Ruehr NK. Tree allocation dynamics beyond heat and hot drought stress reveal changes in carbon storage, belowground translocation and growth. THE NEW PHYTOLOGIST 2022; 233:687-704. [PMID: 34668198 DOI: 10.1111/nph.17815] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 10/12/2021] [Indexed: 06/13/2023]
Abstract
Heatwaves combined with drought affect tree functioning with as yet undetermined legacy effects on carbon (C) and nitrogen (N) allocation. We continuously monitored shoot and root gas exchange, δ13 CO2 of respiration and stem growth in well-watered and drought-treated Pinus sylvestris (Scots pine) seedlings exposed to increasing daytime temperatures (max. 42°C) and evaporative demand. Following stress release, we used 13 CO2 canopy pulse-labeling, supplemented by soil-applied 15 N, to determine allocation to plant compartments, respiration and soil microbial biomass (SMB) over 2.5 wk. Previously heat-treated seedlings rapidly translocated 13 C along the long-distance transport path, to root respiration (Rroot ; 7.1 h) and SMB (3 d). Furthermore, 13 C accumulated in branch cellulose, suggesting secondary growth enhancement. However, in recovering drought-heat seedlings, the mean residence time of 13 C in needles increased, whereas C translocation to Rroot was delayed (13.8 h) and 13 C incorporated into starch rather than cellulose. Concurrently, we observed stress-induced low N uptake and aboveground allocation. C and N allocation during early recovery were affected by stress type and impact. Although C uptake increased quickly in both treatments, drought-heat in combination reduced the above-belowground coupling and starch accumulated in leaves at the expense of growth. Accordingly, C allocation during recovery depends on phloem translocation capacity.
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Affiliation(s)
- Romy Rehschuh
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
| | - Stephanie Rehschuh
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
| | - Andreas Gast
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
| | - Andrea-Livia Jakab
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
| | - Marco M Lehmann
- Swiss Federal Research Institute WSL, Research Unit Forest Dynamics, Birmensdorf, 8903, Switzerland
| | - Matthias Saurer
- Swiss Federal Research Institute WSL, Research Unit Forest Dynamics, Birmensdorf, 8903, Switzerland
| | - Arthur Gessler
- Swiss Federal Research Institute WSL, Research Unit Forest Dynamics, Birmensdorf, 8903, Switzerland
- Department of Environmental System Sciences, ETH Zurich, Zurich, 8092, Switzerland
| | - Nadine K Ruehr
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
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11
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Furze ME, Wainwright DK, Huggett BA, Knipfer T, McElrone AJ, Brodersen CR. Ecologically driven selection of nonstructural carbohydrate storage in oak trees. THE NEW PHYTOLOGIST 2021; 232:567-578. [PMID: 34235751 DOI: 10.1111/nph.17605] [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: 02/08/2021] [Accepted: 06/26/2021] [Indexed: 06/13/2023]
Abstract
Leaf habit is a major axis of plant diversity that has consequences for carbon balance since the leaf is the primary site of photosynthesis. Nonstructural carbohydrates (NSCs) produced by photosynthesis can be allocated to storage and serve as a resiliency mechanism to future abiotic and biotic stress. However, how leaf habit affects NSC storage in an evolutionary context has not been shown. Using a comparative physiological framework and an analysis of evolutionary model fitting, we examined if variation in NSC storage is explained by leaf habit. We measured sugar and starch concentrations in 51 oak species (Quercus spp.) growing in a common garden and representing multiple evolutions of three different leaf habits (deciduous, brevideciduous and evergreen). The best fitting evolutionary models indicated that deciduous oak species are evolving towards higher NSC concentrations than their brevideciduous and evergreen relatives. Notably, this was observed for starch (the primary storage molecule) in the stem (a long-term C storage organ). Overall, our work provides insight into the evolutionary drivers of NSC storage and suggests that a deciduous strategy may confer an advantage against stress associated with a changing world. Future work should examine additional clades to further corroborate this idea.
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Affiliation(s)
- Morgan E Furze
- School of the Environment, Yale University, New Haven, CT, 06511, USA
| | - Dylan K Wainwright
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06511, USA
| | - Brett A Huggett
- Department of Biology, Bates College, Lewiston, ME, 04240, USA
| | - Thorsten Knipfer
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, 95616, USA
| | - Andrew J McElrone
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, 95616, USA
- US Department of Agriculture - Agricultural Research Service, Crops Pathology and Genetics Research Unit, Davis, CA, 95618, USA
| | - Craig R Brodersen
- School of the Environment, Yale University, New Haven, CT, 06511, USA
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12
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Matallana-Ramirez LP, Whetten RW, Sanchez GM, Payn KG. Breeding for Climate Change Resilience: A Case Study of Loblolly Pine ( Pinus taeda L.) in North America. FRONTIERS IN PLANT SCIENCE 2021; 12:606908. [PMID: 33995428 PMCID: PMC8119900 DOI: 10.3389/fpls.2021.606908] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 04/08/2021] [Indexed: 05/25/2023]
Abstract
Earth's atmosphere is warming and the effects of climate change are becoming evident. A key observation is that both the average levels and the variability of temperature and precipitation are changing. Information and data from new technologies are developing in parallel to provide multidisciplinary opportunities to address and overcome the consequences of these changes in forest ecosystems. Changes in temperature and water availability impose multidimensional environmental constraints that trigger changes from the molecular to the forest stand level. These can represent a threat for the normal development of the tree from early seedling recruitment to adulthood both through direct mortality, and by increasing susceptibility to pathogens, insect attack, and fire damage. This review summarizes the strengths and shortcomings of previous work in the areas of genetic variation related to cold and drought stress in forest species with particular emphasis on loblolly pine (Pinus taeda L.), the most-planted tree species in North America. We describe and discuss the implementation of management and breeding strategies to increase resilience and adaptation, and discuss how new technologies in the areas of engineering and genomics are shaping the future of phenotype-genotype studies. Lessons learned from the study of species important in intensively-managed forest ecosystems may also prove to be of value in helping less-intensively managed forest ecosystems adapt to climate change, thereby increasing the sustainability and resilience of forestlands for the future.
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Affiliation(s)
- Lilian P. Matallana-Ramirez
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, Raleigh, NC, United States
| | - Ross W. Whetten
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, Raleigh, NC, United States
| | - Georgina M. Sanchez
- Center for Geospatial Analytics, North Carolina State University, Raleigh, Raleigh, NC, United States
| | - Kitt G. Payn
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, Raleigh, NC, United States
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13
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Sun J, Chen Y, Zhou H, Hu Z, Liao W, Yang Q, Song X. Carbon isotope ratio of leaf litter correlates with litter production in a mangrove ecosystem in South China. MARINE POLLUTION BULLETIN 2020; 157:111224. [PMID: 32658662 DOI: 10.1016/j.marpolbul.2020.111224] [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: 08/17/2019] [Revised: 04/17/2020] [Accepted: 04/23/2020] [Indexed: 06/11/2023]
Abstract
As an important ecological process, litter production is generally recognized as being directly relevant to net primary productivity and carbon storage of mangrove ecosystems. In the present study, we made continuous, monthly assessment of litter production from 2010 to 2016 for five mangrove sites in Shenzhen Futian Mangrove Nature Reserve. Results showed that all mangrove locations displayed distinct seasonality in litter production, and that the alien species produced significantly more litters than the native species. Carbon isotope analysis revealed an interesting, strongly negative relationship between litter production and δ13C of leaf litter (δ13CLL) among the five studied sites. Although it has long been known that δ13C of plant leaves correlates with water use efficiency and some components of plant productivity, the observed δ13CLL-litter production linkage is novel, justifying future exploration of δ13CLL as an potential indicator of litter production and net primary productivity in mangrove ecosystems.
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Affiliation(s)
- Jian Sun
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; Shenzhen Research Institute, Sun Yat-sen University, Shenzhen 518057, China
| | - Yongle Chen
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Haichao Zhou
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China; Shenzhen Key Laboratory of Marine Biological Resources and Ecological Environment, Shenzhen University, Shenzhen 518000, China
| | - Zhangli Hu
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China; Shenzhen Key Laboratory of Marine Biological Resources and Ecological Environment, Shenzhen University, Shenzhen 518000, China
| | - Wenbo Liao
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Qiong Yang
- Guangdong Neilingding Futian National Nature Reserve, Shenzhen 518040, China
| | - Xin Song
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China; Shenzhen Key Laboratory of Marine Biological Resources and Ecological Environment, Shenzhen University, Shenzhen 518000, China.
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14
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Oke TA, Turetsky MR. Evaluating
Sphagnum
traits in the context of resource economics and optimal partitioning theories. OIKOS 2020. [DOI: 10.1111/oik.07195] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tobi A. Oke
- Marine Science Inst., The Univ. of Texas Austin 750 Channel View Drive Port Aransas TX 78373 USA
| | - Merritt R. Turetsky
- Inst. of Arctic and Alpine Research, Univ. of Colorado Boulder, Boulder, CO, USA, and: Dept of Integrative Biology, Univ. of Guelph Guelph ON Canada
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15
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Mannerheim N, Blessing CH, Oren I, Grünzweig JM, Bachofen C, Buchmann N. Carbon allocation to the root system of tropical tree Ceiba pentandra using 13C pulse labelling in an aeroponic facility. TREE PHYSIOLOGY 2020; 40:350-366. [PMID: 31976538 DOI: 10.1093/treephys/tpz142] [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: 01/18/2019] [Revised: 10/28/2019] [Accepted: 12/18/2019] [Indexed: 06/10/2023]
Abstract
Despite the important role of tropical forest ecosystems in the uptake and storage of atmospheric carbon dioxide (CO2), the carbon (C) dynamics of tropical tree species remains poorly understood, especially regarding belowground roots. This study assessed the allocation of newly assimilated C in the fast-growing pioneer tropical tree species Ceiba pentandra (L.), with a special focus on different root categories. During a 5-day pulse-labelling experiment, 9-month-old (~3.5-m-tall) saplings were labelled with 13CO2 in a large-scale aeroponic facility, which allowed tracing the label in bulk biomass and in non-structural carbohydrates (sugars and starch) as well as respiratory CO2 from the canopy to the root system, including both woody and non-woody roots. A combined logistic and exponential model was used to evaluate 13C mean transfer time and mean residence time (MRT) to the root systems. We found 13C in the root phloem as early as 2 h after the labelling, indicating a mean C transfer velocity of 2.4 ± 0.1 m h-1. Five days after pulse labelling, 27% of the tracers taken up by the trees were found in the leaves and 13% were recovered in the woody tissue of the trunk, 6% in the bark and 2% in the root systems, while 52% were lost, most likely by respiration and exudation. Larger amounts of 13C were found in root sugars than in starch, the former also demonstrating shorter MRT than starch. Of all investigated root categories, non-woody white roots (NRW) showed the largest 13C enrichment and peaked in the deepest NRW (2-3.5 m) as early as 24 ± 2 h after labelling. In contrast to coarse woody brown roots, the sink strength of NRW increased with root depth. The findings of this study improve the understanding of C allocation in young tropical trees and provide unique insights into the changing contributions of woody and non-woody roots to C sink strengths with depth.
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Affiliation(s)
- Neringa Mannerheim
- Institute of Agricultural Sciences, ETH Zurich, Universitaetstrasse 2, 8092 Zurich, Switzerland
| | - Carola H Blessing
- Landwirtschaftliches Technologiezentrum Augustenberg, Kutschenweg 20, 76287 Rheinstetten-Forchheim, Germany
| | - Israel Oren
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, POB 12, Rehovot 7610001, Israel
| | - José M Grünzweig
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, POB 12, Rehovot 7610001, Israel
| | - Christoph Bachofen
- Institute of Agricultural Sciences, ETH Zurich, Universitaetstrasse 2, 8092 Zurich, Switzerland
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH Zurich, Universitaetstrasse 2, 8092 Zurich, Switzerland
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16
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Nóbrega C, Marques H, Moreira T. Insights of carbon assimilation and allocation in young cork oak (Quercus suber L.) plants using Carbon-14. PHYSIOLOGIA PLANTARUM 2020; 168:725-735. [PMID: 31381158 DOI: 10.1111/ppl.13017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 07/22/2019] [Accepted: 07/31/2019] [Indexed: 06/10/2023]
Abstract
14 C methods were applied to young, woody, branched and well-watered cork oak (Quercus suber L.) plants to determine carbon assimilation and its distribution among plant organs. Carbon assimilation rates by attached leaves clamped in a foliar 14 CO2 assimilation chamber containing 3.7 × 104 Bq of a portable ventilated diffusion porometer were measured at different 14 CO2 pulse-labeling periods (15, 30, 45, 60 and 120 s) in summer. Allocation of recently fixed C by attached leaves within plants was evaluated 7 days after a 60-min of 5.6 MBq of 14 CO2 pulse-labeling in late winter. 14 CO2 pulse-labeling was separately induced on leaves of a lower branch, two opposite branches at the same lower level, a middle branch and a top branch. 14 C activity incorporated into the plants was measured by liquid scintillation and autoradiography. Our results show the optimum 14 CO2 pulse-labeling period is between 15 and 30 s, which corresponds to 9.81 ± 0.15 and 9.16 ± 0.12 µmol m-2 s-1 C assimilation rates in summer, respectively. The investment of current assimilates ranged from 18 to 29% in leaves, 1 to 7% in lateral branches, 0 to 3% in the stem and over 65% in roots, in late winter. Roots displayed the greatest sink strength for the total 14 C recovered by whole-plants. These results were expected because the trial was done in winter, when cork oak does not produce their leaves. Our results highlight the contribution of current assimilates for growth and maintenance of roots, in young woody plants under Mediterranean climate.
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Affiliation(s)
- Carla Nóbrega
- Unidade Estratégica de Investigação e Seviços dos Sistemas Agrários e Florestais e Sanidade vegetal (UEISSAFSV), Instituto Nacional de Investigação Agrária e Veterinária, I.P., 2780-157, Oeiras, Portugal
| | - Helena Marques
- Departamento de Gestão e Valorização da Floresta (DGVF), Instituto da Conservação da Natureza e das Florestas, I.P., 1050-191, Lisboa, Portugal
| | - Tomaz Moreira
- Colégio Luís António Verney, Universidade de Évora, 7000-671, Évora, Portugal
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17
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Lehmann MM, Goldsmith GR, Mirande-Ney C, Weigt RB, Schönbeck L, Kahmen A, Gessler A, Siegwolf RTW, Saurer M. The 18 O-signal transfer from water vapour to leaf water and assimilates varies among plant species and growth forms. PLANT, CELL & ENVIRONMENT 2020; 43:510-523. [PMID: 31732962 DOI: 10.1111/pce.13682] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 11/11/2019] [Accepted: 11/14/2019] [Indexed: 06/10/2023]
Abstract
The 18 O signature of atmospheric water vapour (δ18 OV ) is known to be transferred via leaf water to assimilates. It remains, however, unclear how the 18 O-signal transfer differs among plant species and growth forms. We performed a 9-hr greenhouse fog experiment (relative humidity ≥ 98%) with 18 O-depleted water vapour (-106.7‰) on 140 plant species of eight different growth forms during daytime. We quantified the 18 O-signal transfer by calculating the mean residence time of O in leaf water (MRTLW ) and sugars (MRTSugars ) and related it to leaf traits and physiological drivers. MRTLW increased with leaf succulence and thickness, varying between 1.4 and 10.8 hr. MRTSugars was shorter in C3 and C4 plants than in crassulacean acid metabolism (CAM) plants and highly variable among species and growth forms; MRTSugars was shortest for grasses and aquatic plants, intermediate for broadleaf trees, shrubs, and herbs, and longest for conifers, epiphytes, and succulents. Sucrose was more sensitive to δ18 OV variations than other assimilates. Our comprehensive study shows that plant species and growth forms vary strongly in their sensitivity to δ18 OV variations, which is important for the interpretation of δ18 O values in plant organic material and compounds and thus for the reconstruction of climatic conditions and plant functional responses.
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Affiliation(s)
- Marco M Lehmann
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, 8903, Switzerland
| | - Gregory R Goldsmith
- Schmid College of Science and Technology, Chapman University, Orange, CA, 92866
| | | | - Rosemarie B Weigt
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, 8903, Switzerland
| | - Leonie Schönbeck
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, 8903, Switzerland
| | - Ansgar Kahmen
- Department of Environmental Sciences-Botany, University of Basel, Basel, 4056, Switzerland
| | - Arthur Gessler
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, 8903, Switzerland
| | - Rolf T W Siegwolf
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, 8903, Switzerland
| | - Matthias Saurer
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, 8903, Switzerland
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18
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Oren I, Mannerheim N, Dumbur R, Fangmeier A, Buchmann N, Grünzweig JM. Patterns and dynamics of canopy-root coupling in tropical tree saplings vary with light intensity but not with root depth. THE NEW PHYTOLOGIST 2020; 225:727-739. [PMID: 31469437 DOI: 10.1111/nph.16153] [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: 06/20/2019] [Accepted: 08/23/2019] [Indexed: 06/10/2023]
Abstract
Carbon (C) dynamics in canopy and roots influence whole-tree carbon fluxes, but little is known about canopy regulation of tree-root activity. Here, the patterns and dynamics of canopy-root C coupling are assessed in tropical trees. Large aeroponics facility was used to study the root systems of Ceiba pentandra and Khaya anthotheca saplings directly at different light intensities. In Ceiba, root respiration (Rr ) co-varied with photosynthesis (An ) in large saplings (3-to-7-m canopy-root axis) at high-light, but showed no consistent pattern at low-light. At medium-light and in small saplings (c. 1-m axis), Rr tended to decrease transiently towards midday. Proximal roots had higher Rr and nonstructural carbohydrate concentrations than distal roots, but canopy-root coupling was unaffected by root location. In medium-sized Khaya, no Rr pattern was observed, and in both species, Rr was unrelated to temperature. The early-afternoon increase in Rr suggests that canopy-root coupling is based on mass flow of newly fixed C in the phloem, whereas the early-morning rise in Rr with An indicates an additional coupling signal that travels faster than the phloem sap. In large saplings and potentially also in higher trees, light and possibly additional environmental factors control the diurnal patterns of canopy-root coupling, irrespective of root location.
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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, Hebrew University of Jerusalem, 7610001, Rehovot, Israel
| | - Neringa Mannerheim
- Institute of Agricultural Sciences, ETH Zürich, Universitätstrasse 2, 8092, Zürich, Switzerland
| | - Rita Dumbur
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, 7610001, Rehovot, Israel
| | - Andreas Fangmeier
- Institute of Landscape and Plant Ecology, University of Hohenheim, August-von-Hartmann-Str. 3, 70599, Stuttgart, Germany
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH Zürich, Universitätstrasse 2, 8092, Zürich, Switzerland
| | - José M Grünzweig
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, 7610001, Rehovot, Israel
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19
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Furze ME, Drake JE, Wiesenbauer J, Richter A, Pendall E. Carbon isotopic tracing of sugars throughout whole-trees exposed to climate warming. PLANT, CELL & ENVIRONMENT 2019; 42:3253-3263. [PMID: 31335973 DOI: 10.1111/pce.13625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 07/16/2019] [Accepted: 07/18/2019] [Indexed: 06/10/2023]
Abstract
Trees allocate C from sources to sinks by way of a series of processes involving carbohydrate transport and utilization. Yet these dynamics are not well characterized in trees, and it is unclear how these dynamics will respond to a warmer world. Here, we conducted a warming and pulse-chase experiment on Eucalyptus parramattensis growing in a whole-tree chamber system to test whether warming impacts carbon allocation by increasing the speed of carbohydrate dynamics. We pulse-labelled large (6-m tall) trees with 13 C-CO2 to follow recently fixed C through different organs by using compound-specific isotope analysis of sugars. We then compared concentrations and mean residence times of individual sugars between ambient and warmed (+3°C) treatments. Trees dynamically allocated 13 C-labelled sugars throughout the aboveground-belowground continuum. We did not, however, find a significant treatment effect on C dynamics, as sugar concentrations and mean residence times were not altered by warming. From the canopy to the root system, 13 C enrichment of sugars decreased, and mean residence times increased, reflecting dilution and mixing of recent photoassimilates with older reserves along the transport pathway. Our results suggest that a locally endemic eucalypt was seemingly able to adjust its physiology to warming representative of future temperature predictions for Australia.
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Affiliation(s)
- Morgan E Furze
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, 02138
| | - John E Drake
- Department of Forest and Natural Resources Management, College of Environmental Science and Forestry, State University of New York, Syracuse, New York, 13210
| | - Julia Wiesenbauer
- Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, 1010, Austria
| | - Andreas Richter
- Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, 1010, Austria
| | - Elise Pendall
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, 2751, Australia
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20
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Lauder JD, Moran EV, Hart SC. Fight or flight? Potential tradeoffs between drought defense and reproduction in conifers. TREE PHYSIOLOGY 2019; 39:1071-1085. [PMID: 30924877 DOI: 10.1093/treephys/tpz031] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 12/26/2018] [Accepted: 03/03/2019] [Indexed: 06/09/2023]
Abstract
Plants frequently exhibit tradeoffs between reproduction and growth when resources are limited, and often change these allocation patterns in response to stress. Shorter-lived plants such as annuals tend to allocate relatively more resources toward reproduction when stressed, while longer-lived plants tend to invest more heavily in survival and stress defense. However, severe stress may affect the fitness implications of allocating relatively more resources to reproduction versus stress defense. Increased drought intensity and duration have led to widespread mortality events in coniferous forests. In this review, we ask how potential tradeoffs between reproduction and survival influence the likelihood of drought-induced mortality and species persistence. We propose that trees may exhibit what we call 'fight or flight' behaviors under stress. 'Fight' behaviors involve greater resource allocation toward survival (e.g., growth, drought-resistant xylem and pest defense). 'Flight' consists of higher relative allocation of resources to reproduction, potentially increasing both offspring production and mortality risk for the adult. We hypothesize that flight behaviors increase as drought stress escalates the likelihood of mortality in a given location.
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Affiliation(s)
- Jeffrey D Lauder
- Quantitative and Systems Biology Graduate Group, University of California, Merced, N. Lake Road, Merced, CA, USA
| | - Emily V Moran
- Department of Life & Environmental Sciences and Sierra Nevada Research Institute, University of California, Merced, N. Lake Road, Merced, CA, USA
| | - Stephen C Hart
- Department of Life & Environmental Sciences and Sierra Nevada Research Institute, University of California, Merced, N. Lake Road, Merced, CA, USA
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21
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Mannerheim N, Werner RA, Buchmann N. Measurement precision and accuracy of high artificial enrichment 15 N and 13 C tracer samples. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2019; 33:1153-1163. [PMID: 30942511 DOI: 10.1002/rcm.8451] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 03/26/2019] [Accepted: 03/27/2019] [Indexed: 06/09/2023]
Abstract
RATIONALE Oversaturation of the Faraday cup amplifiers of isotope ratio mass spectrometers when using tracers that are highly enriched in heavier isotopes (up to 99.9%) remains a major bottleneck to obtaining high-precision measurements. The memory effect plays a key role in reducing tracer sample measurement precision and accuracy. Several sample preparation approaches are known to reduce memory effects and to improve tracer sample measurement precision. However, the potential benefits when using very high enrichment tracer samples (> +1000 mUr) have not been tested. METHODS In this study, we test how specific sample positioning for measurements and frequent use of natural isotope abundance reference materials within the sequence affects the precision and accuracy of isotopic ratio analyses when using a Flash elemental analyser coupled to a Deltaplus XP isotope ratio mass spectrometer for very high enrichment (> +22000 mUr) 15 N tracer sample measurements. Furthermore, we investigate if tracer sample dilution with natural isotope abundance materials reduces memory effects and increases measurement precision and accuracy when measurements of high-enrichment 15 N and 13 C biomass tracer samples are conducted. RESULTS Frequent use of natural isotope abundance materials and specific positioning increased 15 N tracer sample precision, but it had a negative effect on the precision of quality control substances. 15 N and 13 C tracer sample dilution improved measurement precision by a maximum of ±0.9 mUr; however, a strong linear relationship between the original and the calculated φ values was found. Highly enriched 15 N tracer samples caused a maximum memory effect of 0.11%. High levels of 15 N abundance within the samples affected measurement accuracy by an average of 6.7%. CONCLUSIONS We conclude that highly enriched tracer samples do not require dilution before analysis. Tracer sample precision can be improved by using a specific measurement order of expected isotope abundance and by the frequent use of natural abundance reference materials.
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Affiliation(s)
- Neringa Mannerheim
- Institute of Agricultural Sciences, ETH Zurich, Universitätstrasse 2, 8092, Zurich, Switzerland
| | - Roland A Werner
- Institute of Agricultural Sciences, ETH Zurich, Universitätstrasse 2, 8092, Zurich, Switzerland
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH Zurich, Universitätstrasse 2, 8092, Zurich, Switzerland
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Drake JE, Furze ME, Tjoelker MG, Carrillo Y, Barton CVM, Pendall E. Climate warming and tree carbon use efficiency in a whole-tree 13 CO 2 tracer study. THE NEW PHYTOLOGIST 2019; 222:1313-1324. [PMID: 30840319 DOI: 10.1111/nph.15721] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 01/21/2019] [Indexed: 06/09/2023]
Abstract
Autotrophic respiration is a major driver of the global C cycle and may contribute a positive climate warming feedback through increased atmospheric concentrations of CO2 . The extent of this feedback depends on plants' ability to acclimate respiration to maintain a constant carbon use efficiency (CUE). We quantified respiratory partitioning of gross primary production (GPP) and CUE of field-grown trees in a long-term warming experiment (+3°C). We delivered a 13 C-CO2 pulse to whole tree crowns and chased that pulse in the respiration of leaves, whole crowns, roots, and soil. We also measured the isotopic composition of soil microbial biomass and the respiration rates of leaves and whole crowns. We documented homeostatic respiratory acclimation of foliar and whole-crown respiration rates; the trees adjusted to experimental warming such that leaf-level respiration rates were not increased. Experimental warming had no detectable impact on respiratory partitioning or mean residence times. Of the 13 C label acquired by the trees, aboveground respiration consumed 10%, belowground respiration consumed 40%, and the remaining 50% was retained. Experimental warming of +3°C did not alter respiratory partitioning at the scale of entire trees, suggesting that complete acclimation of respiration to warming is likely to dampen a positive climate warming feedback.
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Affiliation(s)
- John E Drake
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
- Department of Forest and Natural Resources Management, College of Environmental Science and Forestry, State University of New York, Syracuse, NY, 13210, USA
| | - Morgan E Furze
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Mark G Tjoelker
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Yolima Carrillo
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Craig V M Barton
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Elise Pendall
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
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23
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Drake JE, Tjoelker MG, Aspinwall MJ, Reich PB, Pfautsch S, Barton CVM. The partitioning of gross primary production for young Eucalyptus tereticornis trees under experimental warming and altered water availability. THE NEW PHYTOLOGIST 2019; 222:1298-1312. [PMID: 30536971 DOI: 10.1111/nph.15629] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 11/20/2018] [Indexed: 05/11/2023]
Abstract
The allocation of carbon (C) is an important component of tree physiology that influences growth and ecosystem C storage. Allocation is challenging to measure, and its sensitivity to environmental changes such as warming and altered water availability is uncertain. We exposed young Eucalyptus tereticornis trees to +3°C warming and elimination of summer precipitation in the field using whole-tree chambers. We calculated C allocation terms using detailed measurements of growth and continuous whole-crown CO2 and water exchange measurements. Trees grew from small saplings to nearly 9 m height during this 15-month experiment. Warming accelerated growth and leaf area development, and it increased the partitioning of gross primary production (GPP) to aboveground respiration and growth while decreasing partitioning below ground. Eliminating summer precipitation reduced C gain and growth but did not impact GPP partitioning. Trees utilized deep soil water and avoided strongly negative water potentials. Warming increased growth respiration, but maintenance respiration acclimated homeostatically. The increasing growth in the warmed treatment resulted in higher rates of respiration, even with complete acclimation of maintenance respiration. Warming-induced stimulations of tree growth likely involve increased C allocation above ground, particularly to leaf area development, whereas reduced water availability may not stimulate allocation to roots.
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Affiliation(s)
- John E Drake
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- Forest and Natural Resources Management, SUNY-ESF, 1 Forestry Drive, Syracuse, NY, 13210, USA
| | - Mark G Tjoelker
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Michael J Aspinwall
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- Department of Biology, University of North Florida, 1 UNF Drive, Jacksonville, FL, 32224, USA
| | - Peter B Reich
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- Department of Forest Resources, University of Minnesota, 1530 Cleveland Ave N., St Paul, MN, 55108, USA
| | - Sebastian Pfautsch
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- School of Social Science and Psychology (Urban Studies), Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Craig V M Barton
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
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24
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Rao S, Wu Y, Wang R. Bicarbonate stimulates non-structural carbohydrate pools of Camptotheca acuminata. PHYSIOLOGIA PLANTARUM 2019; 165:780-789. [PMID: 29900556 DOI: 10.1111/ppl.12785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 06/04/2018] [Accepted: 06/06/2018] [Indexed: 06/08/2023]
Abstract
The role of root-derived dissolved inorganic carbon (DIC) has been emphasized lately, as it can provide an alternative source of carbon for photosynthesis. The fate of newly fixed DIC and its effect on non-structural carbohydrate (NSC) pools has not been thoroughly elucidated to date. To this end, we used 13 C (NaHCO3 ) as a substrate tracer to investigate the incorporation of newly fixed bicarbonate into the plant organs and NSC compounds of Camptotheca acuminata seedlings for 24 and 72 h. NSC levels across the organs were all markedly increased within 24 h of labeling treatment and afterward only decreased in stems at 72 h. The variation range of NSC concentrations in roots was considerably smaller than in the stem and leaves. As time passed, the δ13 C in NSC compounds was significantly affected by 13 C labeling and was more positive in the roots than in the stem and leaves. Starch was more 13 C-enriched than was soluble carbohydrate, and the δ13 C of root starch was as high as -4.70‰. Bicarbonate incorporation into newly formed NSC compounds contributed up to 0.24% of the root starch within 72 h. These data provided strong evidence that bicarbonate not only acted as a C source that contributed slightly to the NSC pools but also stimulated the increase in NSC pools. The present study expands our understanding of the rapid change of NSC pools across the organs in response to bicarbonate.
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Affiliation(s)
- Sen Rao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanyou Wu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Rui Wang
- Food and Pharmaceutical Engineering Institute, Guiyang University, Guiyang 550005, China
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Hesse BD, Goisser M, Hartmann H, Grams TEE. Repeated summer drought delays sugar export from the leaf and impairs phloem transport in mature beech. TREE PHYSIOLOGY 2019; 39:192-200. [PMID: 30388272 DOI: 10.1093/treephys/tpy122] [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: 05/14/2018] [Revised: 09/07/2018] [Accepted: 10/05/2018] [Indexed: 05/24/2023]
Abstract
Phloem sustains maintenance and growth processes through transport of sugars from source to sink organs. Under low water availability, tree functioning is impaired, i.e., growth/photosynthesis decline and phloem transport may be hindered. In a 3-year throughfall exclusion (TE) experiment on mature European beech (Fagus sylvatica L.) we conducted 13CO2 branch labeling to investigate translocation of recently fixed photoassimilates under experimental drought over 2 years (2015 and 2016). We hypothesized (H1) that mean residence time of photoassimilates in leaves (MRT) increases, whereas (H2) phloem transport velocity (Vphloem) decreases under drought. Transport of carbohydrates in the phloem was assessed via δ13C of CO2 efflux measured at two branch positions following 13CO2 labeling. Pre-dawn water potential (ΨPD) and time-integrated soil water deficit (iSWD) were used to quantify drought stress. The MRT increased by 46% from 32.1 ± 5.4 h in control (CO) to 46.9 ± 12.3 h in TE trees, supporting H1, and positively correlated (P < 0.001) with iSWD. Confirming H2, Vphloem in 2016 decreased by 47% from 20.7 ± 5.8 cm h-1 in CO to 11.0 ± 2.9 cm h-1 in TE trees and positively correlated with ΨPD (P = 0.001). We suggest that the positive correlation between MRT and iSWD is a result of the accumulation of osmolytes maintaining cell turgor in the leaves under longer drought periods. Furthermore, we propose that the positive correlation between Vphloem and ΨPD is due to a lower water uptake of phloem conduits from surrounding tissues under increasing drought leading to a higher phloem sap viscosity and lower Vphloem. The two mechanisms increasing MRT and reducing Vphloem respond differently to low water availability and impair trees' carbon translocation under drought.
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Affiliation(s)
- Benjamin D Hesse
- Technical University of Munich, Department of Ecology and Ecosystem Management - Chair for Ecophysiology of Plants, Hans-Carl-von-Carlowitz Platz 2, Freising, Germany
| | - Michael Goisser
- Technical University of Munich, Department of Ecology and Ecosystem Management - Chair for Ecophysiology of Plants, Hans-Carl-von-Carlowitz Platz 2, Freising, Germany
| | - Henrik Hartmann
- Max-Planck Institute for Biogeochemistry, Department of Biogeochemical Processes, Hans Knöll Str. 10, Jena, Germany
| | - Thorsten E E Grams
- Technical University of Munich, Department of Ecology and Ecosystem Management - Chair for Ecophysiology of Plants, Hans-Carl-von-Carlowitz Platz 2, Freising, Germany
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26
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Salmon Y, Dietrich L, Sevanto S, Hölttä T, Dannoura M, Epron D. Drought impacts on tree phloem: from cell-level responses to ecological significance. TREE PHYSIOLOGY 2019; 39:173-191. [PMID: 30726983 DOI: 10.1093/treephys/tpy153] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 12/03/2018] [Accepted: 01/25/2019] [Indexed: 06/09/2023]
Abstract
On-going climate change is increasing the risk of drought stress across large areas worldwide. Such drought events decrease ecosystem productivity and have been increasingly linked to tree mortality. Understanding how trees respond to water shortage is key to predicting the future of ecosystem functions. Phloem is at the core of the tree functions, moving resources such as non-structural carbohydrates, nutrients, and defence and information molecules across the whole plant. Phloem function and ability to transport resources is tightly controlled by the balance of carbon and water fluxes within the tree. As such, drought is expected to impact phloem function by decreasing the amount of available water and new photoassimilates. Yet, the effect of drought on the phloem has received surprisingly little attention in the last decades. Here we review existing knowledge on drought impacts on phloem transport from loading and unloading processes at cellular level to possible effects on long-distance transport and consequences to ecosystems via ecophysiological feedbacks. We also point to new research frontiers that need to be explored to improve our understanding of phloem function under drought. In particular, we show how phloem transport is affected differently by increasing drought intensity, from no response to a slowdown, and explore how severe drought might actually disrupt the phloem transport enough to threaten tree survival. Because transport of resources affects other organisms interacting with the tree, we also review the ecological consequences of phloem response to drought and especially predatory, mutualistic and competitive relations. Finally, as phloem is the main path for carbon from sources to sink, we show how drought can affect biogeochemical cycles through changes in phloem transport. Overall, existing knowledge is consistent with the hypotheses that phloem response to drought matters for understanding tree and ecosystem function. However, future research on a large range of species and ecosystems is urgently needed to gain a comprehensive understanding of the question.
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Affiliation(s)
- Yann Salmon
- Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, Gustaf Hällströmin katu 2b, University of Helsinki, Helsinki, Finland
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, Latokartanonkaari 7, University of Helsinki, Helsinki, Finland
| | - Lars Dietrich
- Department of Environmental Sciences, University of Basel, Schönbeinstrasse 6, Basel, Switzerland
| | - Sanna Sevanto
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, PO Box 1663 MA 495, Los Alamos, NM, USA
| | - Teemu Hölttä
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, Latokartanonkaari 7, University of Helsinki, Helsinki, Finland
| | - Masako Dannoura
- Kyoto University, Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto, Japan
- Kyoto University, Laboratory of Forest Utilization, Graduate School of Agriculture, Kyoto, Japan
| | - Daniel Epron
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
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27
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Hubeau M, Mincke J, Vanhove C, Courtyn J, Vandenberghe S, Steppe K. Plant-PET to investigate phloem vulnerability to drought in Populus tremula under changing climate regimes. TREE PHYSIOLOGY 2019; 39:211-221. [PMID: 30597097 DOI: 10.1093/treephys/tpy131] [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: 04/11/2018] [Revised: 10/24/2018] [Accepted: 11/06/2018] [Indexed: 05/26/2023]
Abstract
Phloem transport is of great importance in trees to distribute assimilated carbon across the entire tree. Nevertheless, knowledge of phloem is incomplete, because of the complexity of measuring its transport and characteristics. Only few studies have addressed how phloem transport might alter under climatic changes, with most data originating from theoretical studies. We measured phloem characteristics in leaves of young Populus tremula L. trees grown during 5 months under ambient (TA, 404 ppm ± 5) and elevated (TE, 659 ppm ± 3) atmospheric CO2 concentration ([CO2]) using a combination of positron emission tomography (PET) and compartmental modelling. Short-term phloem dynamics were measured in vivo and non-invasively using the short-lived isotope of carbon, 11C (half-life 20.4 min). Trees were scanned in well-watered and dry conditions to assess changes in phloem characteristics induced by drought. Reliability of the PET-derived results was verified with reported observations in the literature. Phloem speed was highest in well-watered TE trees and strongly reduced by 81% under drought, whereas phloem speed reduced by 61% in TA trees at the same level of drought. These findings led us to speculate that phloem transport in TE trees might be more vulnerable to drought. We discuss how a higher phloem vulnerability to drought in a changing climate could impact tree hydraulic functioning. Taken together our results suggest that trees grown for 5 months under elevated [CO2] seem to be less well-acclimated to face projected hotter droughts in a changing climate.
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Affiliation(s)
- Michiel Hubeau
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Jens Mincke
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
- Medical Imaging and Signal Processing - Innovative Flemish In-vivo Imaging Technology, Department of Electronics and Information Systems, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium
| | - Christian Vanhove
- Medical Imaging and Signal Processing - Innovative Flemish In-vivo Imaging Technology, Department of Electronics and Information Systems, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium
| | - Jan Courtyn
- Medical Molecular Imaging and Therapy, Department of Radiology and Nuclear Medicine, Ghent University Hospital, Ghent, Belgium
| | - Stefaan Vandenberghe
- Medical Imaging and Signal Processing - Innovative Flemish In-vivo Imaging Technology, Department of Electronics and Information Systems, Faculty of Engineering and Architecture, 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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28
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Dannoura M, Epron D, Desalme D, Massonnet C, Tsuji S, Plain C, Priault P, Gérant D. The impact of prolonged drought on phloem anatomy and phloem transport in young beech trees. TREE PHYSIOLOGY 2019; 39:201-210. [PMID: 29931112 DOI: 10.1093/treephys/tpy070] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/04/2018] [Accepted: 05/18/2018] [Indexed: 06/08/2023]
Abstract
Phloem failure has recently been recognized as one of the mechanisms causing tree mortality under drought, though direct evidence is still lacking. We combined 13C pulse-labelling of 8-year-old beech trees (Fagus sylvatica L.) growing outdoors in a nursery with an anatomical study of the phloem tissue in their stems to examine how drought alters carbon transport and phloem transport capacity. For the six trees under drought, predawn leaf water potential ranged from -0.7 to -2.4 MPa, compared with an average of -0.2 MPa in five control trees with no water stress. We also observed a longer residence time of excess 13C in the foliage and the phloem sap in trees under drought compared with controls. Compared with controls, excess 13C in trunk respiration peaked later in trees under moderate drought conditions and showed no decline even after 4 days under more severe drought conditions. We estimated higher phloem sap viscosity in trees under drought. We also observed much smaller sieve-tube radii in all drought-stressed trees, which led to lower sieve-tube conductivity and lower phloem conductance in the tree stem. We concluded that prolonged drought affected phloem transport capacity through a change in anatomy and that the slowdown of phloem transport under drought likely resulted from a reduced driving force due to lower hydrostatic pressure between the source and sink organs.
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Affiliation(s)
- Masako Dannoura
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
- Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto University, Kyoto, Japan
- Laboratory of Forest Utilization, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Daniel Epron
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Dorine Desalme
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Catherine Massonnet
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Shoko Tsuji
- Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto University, Kyoto, Japan
| | - Caroline Plain
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Pierrick Priault
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Dominique Gérant
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
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29
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Kono Y, Ishida A, Saiki ST, Yoshimura K, Dannoura M, Yazaki K, Kimura F, Yoshimura J, Aikawa SI. Initial hydraulic failure followed by late-stage carbon starvation leads to drought-induced death in the tree Trema orientalis. Commun Biol 2019; 2:8. [PMID: 30623104 PMCID: PMC6323055 DOI: 10.1038/s42003-018-0256-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 12/07/2018] [Indexed: 11/09/2022] Open
Abstract
Drought-induced tree death has become a serious problem in global forest ecosystems. Two nonexclusive hypotheses, hydraulic failure and carbon starvation, have been proposed to explain tree die-offs. To clarify the mechanisms, we investigated the physiological processes of drought-induced tree death in saplings with contrasting Huber values (sapwood area/total leaf area). First, hydraulic failure and reduced respiration were found in the initial process of tree decline, and in the last stage carbon starvation led to tree death. The carbohydrate reserves at the stem bases, low in healthy trees, accumulated at the beginning of the declining process due to phloem transport failure, and then decreased just before dying. The concentrations of non-structural carbohydrates at the stem bases are a good indicator of tree damage. The physiological processes and carbon sink-source dynamics that occur during lethal drought provide important insights into the adaptive measures underlying forest die-offs under global warming conditions.
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Affiliation(s)
- Yuri Kono
- Center for Ecological Research, Kyoto University, Otsu, Shiga 520-2113 Japan
| | - Atsushi Ishida
- Center for Ecological Research, Kyoto University, Otsu, Shiga 520-2113 Japan
| | - Shin-Taro Saiki
- Center for Ecological Research, Kyoto University, Otsu, Shiga 520-2113 Japan
- Forestry and Forest Products Research Institute, Tsukuba, Ibaraki 305-8687 Japan
| | - Kenichi Yoshimura
- Faculty of Agriculture, Yamagata University, Tsuruoka, Yamagata 997-8555 Japan
| | - Masako Dannoura
- Kyoto University Graduate School of Global Environmental Studies, Kyoto, Kyoto 606-8502 Japan
- Faculty of Agriculture, Kyoto University, Kyoto, Kyoto 606-8502 Japan
| | - Kenichi Yazaki
- Forestry and Forest Products Research Institute, Tsukuba, Ibaraki 305-8687 Japan
| | - Fuku Kimura
- Graduate School of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa 252-0880 Japan
| | - Jin Yoshimura
- Graduate School of Science and Technology and Department of Mathematical and Systems Engineering, Shizuoka University, Naka-Ku, Hamamatsu Shizuoka, 432-8561 Japan
- Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210 USA
- Marine Biosystems Research Center, Chiba University, Kamogawa, Chiba 299-5502 Japan
| | - Shin-ichi Aikawa
- Japan Forest Technology Association, Chiyoda, Tokyo 102-5281 Japan
- Graduate School of Science and Engineering, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo 192-0397 Japan
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30
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Marín-Guirao L, Bernardeau-Esteller J, García-Muñoz R, Ramos A, Ontoria Y, Romero J, Pérez M, Ruiz JM, Procaccini G. Carbon economy of Mediterranean seagrasses in response to thermal stress. MARINE POLLUTION BULLETIN 2018; 135:617-629. [PMID: 30301080 DOI: 10.1016/j.marpolbul.2018.07.050] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/16/2018] [Accepted: 07/19/2018] [Indexed: 05/27/2023]
Abstract
Increased plant mortality in temperate seagrass populations has been recently observed after summer heatwaves, although the underlying causes of plant death are yet unknown. The potential energetic constrains resulting from anomalous thermal events could be the reason that triggered seagrass mortality, as demonstrated for benthic invertebrates. To test this hypothesis, the carbon balance of Posidonia oceanica and Cymodocea nodosa plants from contrasting thermal environments was investigated during a simulated heatwave, by analyzing their photosynthetic performance, carbon balance (ratio photosynthesis:respiration), carbohydrates content, growth and mortality. Both species were able to overcome and recover from the thermal stress produced by the six-week exposure to temperatures 4 °C above mean summer levels, albeit plants from cold waters were more sensitive to warming than plants from warm waters as reflected by their inability to maintain their P:R ratio unaltered. The strategies through which plants tend to preserve their energetic status varied depending on the biology of the species and the thermal origin of plants. These included respiratory homeostasis (P. oceanica warm-plants), carbon diversion from growth to respiration (C. nodosa cold-plants) or storage (P. oceanica warm-plants) and changes in biomass allocation (C. nodosa warm-plants). Findings suggest an important geographic heterogeneity in the overall response of Mediterranean seagrasses to warming with potential negative impacts on the functions and services offered by seagrass meadows including among others their capacity for carbon sequestration and carbon export to adjacent ecosystems.
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Affiliation(s)
- L Marín-Guirao
- Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy.
| | - J Bernardeau-Esteller
- Seagrass Ecology Group, Oceanographic Center of Murcia, Spanish Institute of Oceanography C/Varadero, 30740 San Pedro del Pinatar, Murcia, Spain
| | - R García-Muñoz
- Seagrass Ecology Group, Oceanographic Center of Murcia, Spanish Institute of Oceanography C/Varadero, 30740 San Pedro del Pinatar, Murcia, Spain
| | - A Ramos
- Seagrass Ecology Group, Oceanographic Center of Murcia, Spanish Institute of Oceanography C/Varadero, 30740 San Pedro del Pinatar, Murcia, Spain
| | - Y Ontoria
- Department of Evolutionary Biology, Ecology, and Environmental Sciences, Universitat de Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain
| | - J Romero
- Department of Evolutionary Biology, Ecology, and Environmental Sciences, Universitat de Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain
| | - M Pérez
- Department of Evolutionary Biology, Ecology, and Environmental Sciences, Universitat de Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain
| | - J M Ruiz
- Seagrass Ecology Group, Oceanographic Center of Murcia, Spanish Institute of Oceanography C/Varadero, 30740 San Pedro del Pinatar, Murcia, Spain
| | - G Procaccini
- Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
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Klimešová J, Martínková J, Ottaviani G. Belowground plant functional ecology: Towards an integrated perspective. Funct Ecol 2018. [DOI: 10.1111/1365-2435.13145] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jitka Klimešová
- Department of Functional EcologyInstitute of BotanyCzech Academy of Sciences Třeboň Czech Republic
- Department of BotanyFaculty of ScienceCharles University Praha Czech Republic
| | - Jana Martínková
- Department of Functional EcologyInstitute of BotanyCzech Academy of Sciences Třeboň Czech Republic
| | - Gianluigi Ottaviani
- Department of Functional EcologyInstitute of BotanyCzech Academy of Sciences Třeboň Czech Republic
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Pflug EE, Buchmann N, Siegwolf RTW, Schaub M, Rigling A, Arend M. Resilient Leaf Physiological Response of European Beech ( Fagus sylvatica L.) to Summer Drought and Drought Release. FRONTIERS IN PLANT SCIENCE 2018; 9:187. [PMID: 29515605 PMCID: PMC5825912 DOI: 10.3389/fpls.2018.00187] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 01/31/2018] [Indexed: 05/22/2023]
Abstract
Drought is a major environmental constraint to trees, causing severe stress and thus adversely affecting their functional integrity. European beech (Fagus sylvatica L.) is a key species in mesic forests that is commonly expected to suffer in a future climate with more intense and frequent droughts. Here, we assessed the seasonal response of leaf physiological characteristics of beech saplings to drought and drought release to investigate their potential to recover from the imposed stress and overcome previous limitations. Saplings were transplanted to model ecosystems and exposed to a simulated summer drought. Pre-dawn water potentials (ψpd), stomatal conductance (gS), intercellular CO2 concentration (ci), net-photosynthesis (AN), PSII chlorophyll fluorescence (PItot), non-structural carbohydrate concentrations (NSC; soluble sugars, starch) and carbon isotope signatures were measured in leaves throughout the growing season. Pre-dawn water potentials (ψpd), gS, ci, AN, and PItot decreased as drought progressed, and the concentration of soluble sugars increased at the expense of starch. Carbon isotopes in soluble sugars (δ13CS) showed a distinct increase under drought, suggesting, together with decreased ci, stomatal limitation of AN. Drought effects on ψpd, ci, and NSC disappeared shortly after re-watering, while full recovery of gS, AN, and PItot was delayed by 1 week. The fast recovery of NSC was reflected by a rapid decay of the drought signal in δ13C values, indicating a rapid turnover of assimilates and a reactivation of carbon metabolism. After recovery, the previously drought-exposed saplings showed a stimulation of AN and a trend toward elevated starch concentrations, which counteracted the previous drought limitations. Overall, our results suggest that the internal water relations of beech saplings and the physiological activity of leaves are restored rapidly after drought release. In the case of AN, stimulation after drought may partially compensate for limitations on photosynthetic activity during drought. Our observations suggest high resilience of beech to drought, contradicting the general belief that beech is particularly sensitive to environmental stressors.
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Affiliation(s)
- Ellen E. Pflug
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
- Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Rolf T. W. Siegwolf
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, Switzerland
| | - Marcus Schaub
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
| | - Andreas Rigling
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
| | - Matthias Arend
- Physiological Plant Ecology, University of Basel, Basel, Switzerland
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Galiano L, Timofeeva G, Saurer M, Siegwolf R, Martínez-Vilalta J, Hommel R, Gessler A. The fate of recently fixed carbon after drought release: towards unravelling C storage regulation in Tilia platyphyllos and Pinus sylvestris. PLANT, CELL & ENVIRONMENT 2017; 40:1711-1724. [PMID: 28432768 DOI: 10.1111/pce.12972] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 04/04/2017] [Accepted: 04/07/2017] [Indexed: 06/07/2023]
Abstract
Carbon reserves are important for maintaining tree function during and after stress. Increasing tree mortality driven by drought globally has renewed the interest in how plants regulate allocation of recently fixed C to reserve formation. Three-year-old seedlings of two species (Tilia platyphyllos and Pinus sylvestris) were exposed to two intensities of experimental drought during ~10 weeks, and 13 C pulse labelling was subsequently applied with rewetting. Tracking the 13 C label across different organs and C compounds (soluble sugars, starch, myo-inositol, lipids and cellulose), together with the monitoring of gas exchange and C mass balances over time, allowed for the identification of variations in C allocation priorities and tree C balances that are associated with drought effects and subsequent drought release. The results demonstrate that soluble sugars accumulated in P. sylvestris under drought conditions independently of growth trends; thus, non-structural carbohydrates (NSC) formation cannot be simply considered a passive overflow process in this species. Once drought ceased, C allocation to storage was still prioritized at the expense of growth, which suggested the presence of 'drought memory effects', possibly to ensure future growth and survival. On the contrary, NSC and growth dynamics in T. platyphyllos were consistent with a passive (overflow) view of NSC formation.
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Affiliation(s)
- Lucía Galiano
- Swiss Federal Research Institute WSL, Birmensdorf, CH-8903, Switzerland
- Institute of Hydrology, University of Freiburg, Freiburg, D-79098, Germany
| | - Galina Timofeeva
- Swiss Federal Research Institute WSL, Birmensdorf, CH-8903, Switzerland
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute PSI, Villigen, CH-5232, Switzerland
- Forest Ecology, Department of Environmental Systems Science, Institute of Terrestrial Ecosystems, ETH Zürich, Zürich, CH-8092, Switzerland
| | - Matthias Saurer
- Swiss Federal Research Institute WSL, Birmensdorf, CH-8903, Switzerland
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute PSI, Villigen, CH-5232, Switzerland
| | - Rolf Siegwolf
- Swiss Federal Research Institute WSL, Birmensdorf, CH-8903, Switzerland
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute PSI, Villigen, CH-5232, Switzerland
| | - Jordi Martínez-Vilalta
- CREAF, Cerdanyola del Vallès, E-08193, Spain
- Autonomous University of Barcelona UAB, Cerdanyola del Vallès, E-08193, Spain
| | - Robert Hommel
- Eberswalde University of Sustainable Development, Schicklerstraße 5, 16225, Eberswalde, Germany
| | - Arthur Gessler
- Swiss Federal Research Institute WSL, Birmensdorf, CH-8903, Switzerland
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Hacket-Pain AJ, Lageard JGA, Thomas PA. Drought and reproductive effort interact to control growth of a temperate broadleaved tree species (Fagus sylvatica). TREE PHYSIOLOGY 2017; 37:744-754. [PMID: 28338975 DOI: 10.1093/treephys/tpx025] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 02/27/2017] [Indexed: 06/06/2023]
Abstract
Interannual variation in radial growth is influenced by a range of physiological processes, including variation in annual reproductive effort, although the importance of reproductive allocation has rarely been quantified. In this study, we use long stand-level records of annual seed production, radial growth (tree ring width) and meteorological conditions to analyse the relative importance of summer drought and reproductive effort in controlling the growth of Fagus sylvatica L., a typical masting species. We show that both summer drought and reproductive effort (masting) influenced growth. Importantly, the effects of summer drought and masting were interactive, with the greatest reductions in growth found in years when high reproductive effort (i.e., mast years) coincided with summer drought. Conversely, mast years that coincided with non-drought summers were associated with little reduction in radial growth, as were drought years that did not coincide with mast years. The results show that the strength of an inferred trade-off between growth and reproduction in this species (the cost of reproduction) is dependent on environmental stress, with a stronger trade-off in years with more stressful growing conditions. These results have widespread implications for understanding interannual variability in growth, and observed relationships between growth and climate.
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Affiliation(s)
- Andrew J Hacket-Pain
- St Catherine's College, Manor Road, Oxford OX1 3UJ, UK
- Fitzwilliam College, Storey's Way, Cambridge CB3 0DG, UK
| | - Jonathan G A Lageard
- Division of Geography and Environmental Management, Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, UK
| | - Peter A Thomas
- School of Life Sciences, Keele University, Keele, Staffordshire ST5 5BG, UK
- Harvard Forest, Harvard University, Harvard Forest, 324 North Main Street, Petersham, MA 01366, USA
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Liesche J. Sucrose transporters and plasmodesmal regulation in passive phloem loading. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2017; 59:311-321. [PMID: 28429873 DOI: 10.1111/jipb.12548] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 04/21/2017] [Indexed: 06/07/2023]
Abstract
An essential step for the distribution of carbon throughout the whole plant is the loading of sugars into the phloem in source organs. In many plants, accumulation of sugars in the sieve element-companion cell (SE-CC) complex is mediated and regulated by active processes. However, for poplar and many other tree species, a passive symplasmic mechanism of phloem loading has been proposed, characterized by symplasmic continuity along the pre-phloem pathway and the absence of active sugar accumulation in the SE-CC complex. A high overall leaf sugar concentration is thought to enable diffusion of sucrose into the phloem. In this review, we critically evaluate current evidence regarding the mechanism of passive symplasmic phloem loading, with a focus on the potential influence of active sugar transport and plasmodesmal regulation. The limited experimental data, combined with theoretical considerations, suggest that a concomitant operation of passive symplasmic and active phloem loading in the same minor vein is unlikely. However, active sugar transport could well play an important role in how passively loading plants might modulate the rate of sugar export from leaves. Insights into the operation of this mechanism has direct implications for our understanding of how these plants utilize assimilated carbon.
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Affiliation(s)
- Johannes Liesche
- College of Life Science, Northwest A&F University, No 3 Taicheng Road, Yangling 712100, China
- Biomass Energy Center for Arid and Semi-arid lands, Northwest A&F University, Yangling 712100, China
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Liu JF, Arend M, Yang WJ, Schaub M, Ni YY, Gessler A, Jiang ZP, Rigling A, Li MH. Effects of drought on leaf carbon source and growth of European beech are modulated by soil type. Sci Rep 2017; 7:42462. [PMID: 28195166 PMCID: PMC5307967 DOI: 10.1038/srep42462] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 01/11/2017] [Indexed: 02/01/2023] Open
Abstract
Drought potentially affects carbon balance and growth of trees, but little is known to what extent soil plays a role in the trade-off between carbon gain and growth investment. In the present study, we analyzed leaf non-structural carbohydrates (NSC) as an indicator of the balance of photosynthetic carbon gain and carbon use, as well as growth of European beech (Fagus sylvatica L.) saplings, which were grown on two different soil types (calcareous and acidic) in model ecosystems and subjected to a severe summer drought. Our results showed that drought led in general to increased total NSC concentrations and to decreased growth rate, and drought reduced shoot and stem growth of plants in acidic soil rather than in calcareous soil. This result indicated that soil type modulated the carbon trade-off between net leaf carbon gain and carbon investment to growth. In drought-stressed trees, leaf starch concentration and growth correlated negatively whereas soluble sugar:starch ratio and growth correlated positively, which may contribute to a better understanding of growth regulation under drought conditions. Our results emphasize the role of soil in determining the trade-off between the balance of carbon gain and carbon use on the leaf level and growth under stress (e.g. drought).
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Affiliation(s)
- Jian-Feng Liu
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China
- Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland
| | - Matthias Arend
- Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland
- Institute of Botany, University of Basel, Basel, Switzerland
| | - Wen-Juan Yang
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China
| | - Marcus Schaub
- Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland
| | - Yan-Yan Ni
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China
| | - Arthur Gessler
- Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland
- Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
| | - Ze-Ping Jiang
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China
| | - Andreas Rigling
- Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland
| | - Mai-He Li
- Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
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Marias DE, Meinzer FC, Still C. Impacts of leaf age and heat stress duration on photosynthetic gas exchange and foliar nonstructural carbohydrates in Coffea arabica. Ecol Evol 2017; 7:1297-1310. [PMID: 28303198 PMCID: PMC5306013 DOI: 10.1002/ece3.2681] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/28/2016] [Accepted: 11/27/2016] [Indexed: 01/04/2023] Open
Abstract
Given future climate predictions of increased temperature, and frequency and intensity of heat waves in the tropics, suitable habitat to grow ecologically, economically, and socially valuable Coffea arabica is severely threatened. We investigated how leaf age and heat stress duration impact recovery from heat stress in C. arabica. Treated plants were heated in a growth chamber at 49°C for 45 or 90 min. Physiological recovery was monitored in situ using gas exchange, chlorophyll fluorescence (the ratio of variable to maximum fluorescence, FV/FM), and leaf nonstructural carbohydrate (NSC) on mature and expanding leaves before and 2, 15, 25, and 50 days after treatment. Regardless of leaf age, the 90-min treatment resulted in greater FV/FM reduction 2 days after treatment and slower recovery than the 45-min treatment. In both treatments, photosynthesis of expanding leaves recovered more slowly than in mature leaves. Stomatal conductance (gs) decreased in expanding leaves but did not change in mature leaves. These responses led to reduced intrinsic water-use efficiency with increasing heat stress duration in both age classes. Based on a leaf energy balance model, aftereffects of heat stress would be exacerbated by increases in leaf temperature at low gs under full sunlight where C. arabica is often grown, but also under partial sunlight. Starch and total NSC content of the 45-min group significantly decreased 2 days after treatment and then accumulated 15 and 25 days after treatment coinciding with recovery of photosynthesis and FV/FM. In contrast, sucrose of the 90-min group accumulated at day 2 suggesting that phloem transport was inhibited. Both treatment group responses contrasted with control plant total NSC and starch, which declined with time associated with subsequent flower and fruit production. No treated plants produced flowers or fruits, suggesting that short duration heat stress can lead to crop failure.
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Affiliation(s)
- Danielle E. Marias
- Department of Forest Ecosystems and SocietyOregon State UniversityCorvallisORUSA
| | | | - Christopher Still
- Department of Forest Ecosystems and SocietyOregon State UniversityCorvallisORUSA
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Desalme D, Priault P, Gérant D, Dannoura M, Maillard P, Plain C, Epron D. Seasonal variations drive short-term dynamics and partitioning of recently assimilated carbon in the foliage of adult beech and pine. THE NEW PHYTOLOGIST 2017; 213:140-153. [PMID: 27513732 DOI: 10.1111/nph.14124] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 06/28/2016] [Indexed: 06/06/2023]
Abstract
13 CO2 pulse-labelling experiments were performed in situ on adult beeches (Fagus sylvatica) and pines (Pinus pinaster) at different phenological stages to study seasonal and interspecific short-term dynamics and partitioning of recently assimilated carbon (C) in leaves. Polar fraction (PF, including soluble sugars, amino acids and organic acids) and starch were purified from foliage sampled during a 10-d chase period. C contents, isotopic compositions and 13 C dynamics parameters were determined in bulk foliage, PF and starch. Decrease in 13 C amount in bulk foliage followed a two-pool exponential model highlighting 13 C partitioning between 'mobile' and 'stable' pools, the relative proportion of the latter being maximal in beech leaves in May. Early in the growing season, new foliage acted as a strong C sink in both species, but although young leaves and needles were already photosynthesizing, the latter were still supplied with previous-year needle photosynthates 2 months after budburst. Mean 13 C residence times (MRT) were minimal in summer, indicating fast photosynthate export to supply perennial organ growth in both species. In late summer, MRT differed between senescing beech leaves and overwintering pine needles. Seasonal variations of 13 C partitioning and dynamics in field-grown tree foliage are closely linked to phenological differences between deciduous and evergreen trees.
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Affiliation(s)
- Dorine Desalme
- Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France
| | - Pierrick Priault
- Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France
| | - Dominique Gérant
- Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France
| | - Masako Dannoura
- INRA, UMR 1263, F-33883 Villenave d'Ornon, France
- Laboratory of Forest Utilization, Kyoto University, Kyoto 606-8502, Japan
| | - Pascale Maillard
- Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France
| | - Caroline Plain
- Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France
| | - Daniel Epron
- Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France
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39
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Soil microbial communities buffer physiological responses to drought stress in three hardwood species. Oecologia 2016; 183:631-641. [DOI: 10.1007/s00442-016-3783-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 11/17/2016] [Indexed: 02/07/2023]
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Blessing CH, Barthel M, Gentsch L, Buchmann N. Strong Coupling of Shoot Assimilation and Soil Respiration during Drought and Recovery Periods in Beech As Indicated by Natural Abundance δ 13C Measurements. FRONTIERS IN PLANT SCIENCE 2016; 7:1710. [PMID: 27909442 PMCID: PMC5112276 DOI: 10.3389/fpls.2016.01710] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 10/31/2016] [Indexed: 05/27/2023]
Abstract
Drought down-regulates above- and belowground carbon fluxes, however, the resilience of trees to drought will also depend on the speed and magnitude of recovery of these above- and belowground fluxes after re-wetting. Carbon isotope composition of above- and belowground carbon fluxes at natural abundance provides a methodological approach to study the coupling between photosynthesis and soil respiration (SR) under conditions (such as drought) that influence photosynthetic carbon isotope discrimination. In turn, the direct supply of root respiration with recent photoassimilates will impact on the carbon isotope composition of soil-respired CO2. We independently measured shoot and soil CO2 fluxes of beech saplings (Fagus sylvatica L.) and their respective δ13C continuously with laser spectroscopy at natural abundance. We quantified the speed of recovery of drought stressed trees after re-watering and traced photosynthetic carbon isotope signal in the carbon isotope composition of soil-respired CO2. Stomatal conductance responded strongly to the moderate drought (-65%), induced by reduced soil moisture content as well as increased vapor pressure deficit. Simultaneously, carbon isotope discrimination decreased by 8‰, which in turn caused a significant increase in δ13C of recent metabolites (1.5-2.5‰) and in δ13C of SR (1-1.5‰). Generally, shoot and soil CO2 fluxes and their δ13C were in alignment during drought and subsequent stress release, clearly demonstrating a permanent dependence of root respiration on recently fixed photoassimilates, rather than on older reserves. After re-watering, the drought signal persisted longer in δ13C of the water soluble fraction that integrates multiple metabolites (soluble sugars, amino acids, organic acids) than in the neutral fraction which represents most recently assimilated sugars or in the δ13C of SR. Nevertheless, full recovery of all aboveground physiological variables was reached within 4 days - and within 7 days for SR - indicating high resilience of (young) beech against moderate drought.
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Affiliation(s)
- Carola H. Blessing
- Centre for Carbon Water and Food, University of Sydney, Brownlow HillNSW, Australia
- Institute of Agricultural Sciences, ETH ZürichZürich, Switzerland
| | - Matti Barthel
- Institute of Agricultural Sciences, ETH ZürichZürich, Switzerland
| | - Lydia Gentsch
- Chair of Bioclimatology, Georg-August University of GöttingenGöttingen, Germany
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH ZürichZürich, Switzerland
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Hommel R, Siegwolf R, Zavadlav S, Arend M, Schaub M, Galiano L, Haeni M, Kayler ZE, Gessler A. Impact of interspecific competition and drought on the allocation of new assimilates in trees. PLANT BIOLOGY (STUTTGART, GERMANY) 2016; 18:785-96. [PMID: 27061772 DOI: 10.1111/plb.12461] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 04/07/2016] [Indexed: 05/21/2023]
Abstract
In trees, the interplay between reduced carbon assimilation and the inability to transport carbohydrates to the sites of demand under drought might be one of the mechanisms leading to carbon starvation. However, we largely lack knowledge on how drought effects on new assimilate allocation differ between species with different drought sensitivities and how these effects are modified by interspecific competition. We assessed the fate of (13) C labelled assimilates in above- and belowground plant organs and in root/rhizosphere respired CO2 in saplings of drought-tolerant Norway maple (Acer platanoides) and drought-sensitive European beech (Fagus sylvatica) exposed to moderate drought, either in mono- or mixed culture. While drought reduced stomatal conductance and photosynthesis rates in both species, both maintained assimilate transport belowground. Beech even allocated more new assimilate to the roots under moderate drought compared to non-limited water supply conditions, and this pattern was even more pronounced under interspecific competition. Even though maple was a superior competitor compared to beech under non-limited soil water conditions, as indicated by the changes in above- and belowground biomass of both species in the interspecific competition treatments, we can state that beech was still able to efficiently allocate new assimilate belowground under combined drought and interspecific competition. This might be seen as a strategy to maintain root osmotic potential and to prioritise root functioning. Our results thus show that beech tolerates moderate drought stress plus competition without losing its ability to supply belowground tissues. It remains to be explored in future work if this strategy is also valid during long-term drought exposure.
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Affiliation(s)
- R Hommel
- Leibniz Centre for Agricultural Landscape Research (ZALF), Institute for Landscape Biogeochemistry, Müncheberg, Germany
| | - R Siegwolf
- Laboratory of Atmospheric Chemistry, Stable Isotopes and Ecosystem Fluxes, Paul Scherrer Institute (PSI), Villigen, Switzerland
| | - S Zavadlav
- Department of Forest Physiology and Genetics, Ljubljana, Slovenia
| | - M Arend
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
| | - M Schaub
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
| | - L Galiano
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
- Institute of Hydrology, University of Freiburg, Freiburg, Germany
| | - M Haeni
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
| | - Z E Kayler
- Leibniz Centre for Agricultural Landscape Research (ZALF), Institute for Landscape Biogeochemistry, Müncheberg, Germany
| | - A Gessler
- Leibniz Centre for Agricultural Landscape Research (ZALF), Institute for Landscape Biogeochemistry, Müncheberg, Germany
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
- Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
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Batista Silva W, Daloso DM, Fernie AR, Nunes-Nesi A, Araújo WL. Can stable isotope mass spectrometry replace radiolabelled approaches in metabolic studies? PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2016; 249:59-69. [PMID: 27297990 DOI: 10.1016/j.plantsci.2016.05.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 04/21/2016] [Accepted: 05/13/2016] [Indexed: 05/03/2023]
Abstract
Metabolic pathways and the key regulatory points thereof can be deduced using isotopically labelled substrates. One prerequisite is the accurate measurement of the labeling pattern of targeted metabolites. The subsequent estimation of metabolic fluxes following incubation in radiolabelled substrates has been extensively used. Radiolabelling is a sensitive approach and allows determination of total label uptake since the total radiolabel content is easy to detect. However, the incubation of cells, tissues or the whole plant in a stable isotope enriched environment and the use of either mass spectrometry or nuclear magnetic resonance techniques to determine label incorporation within specific metabolites offers the possibility to readily obtain metabolic information with higher resolution. It additionally also offers an important complement to other post-genomic strategies such as metabolite profiling providing insights into the regulation of the metabolic network and thus allowing a more thorough description of plant cellular function. Thus, although safety concerns mean that stable isotope feeding is generally preferred, the techniques are in truth highly complementary and application of both approaches in tandem currently probably provides the best route towards a comprehensive understanding of plant cellular metabolism.
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Affiliation(s)
- Willian Batista Silva
- Max Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa-MG, Brazil.
| | - Danilo M Daloso
- Max-Planck-Institute of Molecular Plant Physiology Am Mühlenberg 1, 14476,Golm Potsdam, Germany.
| | - Alisdair R Fernie
- Max-Planck-Institute of Molecular Plant Physiology Am Mühlenberg 1, 14476,Golm Potsdam, Germany.
| | - Adriano Nunes-Nesi
- Max Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa-MG, Brazil.
| | - Wagner L Araújo
- Max Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa-MG, Brazil.
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Hartmann H, Trumbore S. Understanding the roles of nonstructural carbohydrates in forest trees - from what we can measure to what we want to know. THE NEW PHYTOLOGIST 2016; 211:386-403. [PMID: 27061438 DOI: 10.1111/nph.13955] [Citation(s) in RCA: 264] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/01/2016] [Indexed: 05/17/2023]
Abstract
Contents 386 I. 386 II. 388 III. 392 IV. 392 V. 396 VI. 399 399 References 399 SUMMARY: Carbohydrates provide the building blocks for plant structures as well as versatile resources for metabolic processes. The nonstructural carbohydrates (NSC), mainly sugars and starch, fulfil distinct functional roles, including transport, energy metabolism and osmoregulation, and provide substrates for the synthesis of defence compounds or exchange with symbionts involved in nutrient acquisition or defence. At the whole-plant level, NSC storage buffers the asynchrony of supply and demand on diel, seasonal or decadal temporal scales and across plant organs. Despite its central role in plant function and in stand-level carbon cycling, our understanding of storage dynamics, its controls and response to environmental stresses is very limited, even after a century of research. This reflects the fact that often storage is defined by what we can measure, that is, NSC concentrations, and the interpretation of these as a proxy for a single function, storage, rather than the outcome of a range of NSC source and sink functions. New isotopic tools allow direct quantification of timescales involved in NSC dynamics, and show that NSC-C fixed years to decades previously is used to support tree functions. Here we review recent advances, with emphasis on the context of the interactions between NSC, drought and tree mortality.
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Affiliation(s)
- Henrik Hartmann
- Max-Planck Institute for Biogeochemistry, Hans Knöll Str. 10, 07745, Jena, Germany
| | - Susan Trumbore
- Max-Planck Institute for Biogeochemistry, Hans Knöll Str. 10, 07745, Jena, Germany
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Carbon Allocation into Different Fine-Root Classes of Young Abies alba Trees Is Affected More by Phenology than by Simulated Browsing. PLoS One 2016; 11:e0154687. [PMID: 27123860 PMCID: PMC4849635 DOI: 10.1371/journal.pone.0154687] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 04/18/2016] [Indexed: 12/02/2022] Open
Abstract
Abies alba (European silver fir) was used to investigate possible effects of simulated browsing on C allocation belowground by 13CO2 pulse-labelling at spring, summer or autumn, and by harvesting the trees at the same time point of the labelling or at a later season for biomass and for 13C-allocation into the fine-root system. Before budburst in spring, the leader shoots and 50% of all lateral shoots of half of the investigated 5-year old Abies alba saplings were clipped to simulate browsing. At harvest, different fine-root classes were separated, and starch as an important storage compartment was analysed for concentrations. The phenology had a strong effect on the allocation of the 13C-label from shoots to roots. In spring, shoots did not supply the fine-roots with high amounts of the 13C-label, because the fine-roots contained less than 1% of the applied 13C. In summer and autumn, however, shoots allocated relatively high amounts of the 13C-label to the fine roots. The incorporation of the 13C-label as structural C or as starch into the roots is strongly dependent on the root type and the root diameter. In newly formed fine roots, 3–5% of the applied 13C was incorporated, whereas 1–3% in the ≤0.5 mm root class and 1–1.5% in the >0.5–1.0 mm root class were recorded. Highest 13C-enrichment in the starch was recorded in the newly formed fine roots in autumn. The clipping treatment had a significant positive effect on the amount of allocated 13C-label to the fine roots after the spring labelling, with high relative 13C-contents observed in the ≤0.5 mm and the >0.5–1.0 mm fine-root classes of clipped trees. No effects of the clipping were observed after summer and autumn labelling in the 13C-allocation patterns. Overall, our data imply that the season of C assimilation and, thus, the phenology of trees is the main determinant of the C allocation from shoots to roots and is clearly more important than browsing.
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Sevanto S, Dickman LT. Where does the carbon go?--Plant carbon allocation under climate change. TREE PHYSIOLOGY 2015; 35:581-584. [PMID: 26109074 DOI: 10.1093/treephys/tpv059] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Affiliation(s)
- Sanna Sevanto
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Bikini Atoll Road MS J495, Los Alamos, NM 87545, USA
| | - L Turin Dickman
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Bikini Atoll Road MS J495, Los Alamos, NM 87545, USA
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