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Knüver T, Bär A, Ganthaler A, Gebhardt T, Grams TEE, Häberle K, Hesse BD, Losso A, Tomedi I, Mayr S, Beikircher B. Recovery after long-term summer drought: Hydraulic measurements reveal legacy effects in trunks of Picea abies but not in Fagus sylvatica. PLANT BIOLOGY (STUTTGART, GERMANY) 2022; 24:1240-1253. [PMID: 35611757 PMCID: PMC10084041 DOI: 10.1111/plb.13444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
Climate change is expected to increase the frequency and intensity of summer droughts. Sufficient drought resistance, the ability to acclimate to and/or recover after drought, is thus crucial for forest tree species. However, studies on the hydraulics of mature trees during and after drought in natura are scarce. In this study, we analysed trunk water content (electrical resistivity: ER) and further hydraulic (water potential, sap flow density, specific hydraulic conductivity, vulnerability to embolism) as well as wood anatomical traits (tree ring width, conduit diameter, conduit wall reinforcement) of drought-stressed (artificially induced summer drought via throughfall-exclusion) and unstressed Picea abies and Fagus sylvatica trees. In P. abies, ER indicated a strong reduction in trunk water content after 5 years of summer drought, corresponding to significantly lower pre-dawn leaf water potential and xylem sap flow density. Vulnerability to embolism tended to be higher in drought-stressed trees. In F. sylvatica, only small differences between drought-stressed and control trees were observed. Re-watering led to a rapid increase in water potentials and xylem sap flow of both drought-stressed trees, and to increased growth rates in the next growing season. ER analyses revealed lower trunk water content in P. abies trees growing on throughfall-exclusion plots even 1 year after re-watering, indicating a limited capacity to restore internal water reserves. Results demonstrated that P. abies is more susceptible to recurrent summer drought than F. sylvatica, and can exhibit long-lasting and pronounced legacy effects in trunk water reserves.
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Affiliation(s)
- T. Knüver
- Department of BotanyUniversity of InnsbruckInnsbruckAustria
| | - A. Bär
- Department of BotanyUniversity of InnsbruckInnsbruckAustria
| | - A. Ganthaler
- Department of BotanyUniversity of InnsbruckInnsbruckAustria
| | - T. Gebhardt
- Technical University of MunichSchool of Life SciencesProfessorship for Land Surface‐Atmosphere Interactions AG Ecophysiology of PlantsFreisingGermany
| | - T. E. E. Grams
- Technical University of MunichSchool of Life SciencesProfessorship for Land Surface‐Atmosphere Interactions AG Ecophysiology of PlantsFreisingGermany
| | - K.‐H. Häberle
- Technical University of MunichSchool of Life SciencesChair of Restoration EcologyFreisingGermany
| | - B. D. Hesse
- Technical University of MunichSchool of Life SciencesProfessorship for Land Surface‐Atmosphere Interactions AG Ecophysiology of PlantsFreisingGermany
| | - A. Losso
- Department of BotanyUniversity of InnsbruckInnsbruckAustria
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityRichmondAustralia
| | - I. Tomedi
- Department of BotanyUniversity of InnsbruckInnsbruckAustria
| | - S. Mayr
- Department of BotanyUniversity of InnsbruckInnsbruckAustria
| | - B. Beikircher
- Department of BotanyUniversity of InnsbruckInnsbruckAustria
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2
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Taneda H, Ogasa MY, Yazaki K, Funayama-Noguchi S, Miyazawa Y, Mayr S, Maruta E. Impact of freeze-thaw-induced pit aspiration on stem water transport in the subalpine conifer Abies veitchii. PLANT PHYSIOLOGY 2022; 190:1687-1698. [PMID: 35997583 PMCID: PMC9614463 DOI: 10.1093/plphys/kiac388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 07/21/2022] [Indexed: 06/15/2023]
Abstract
During winter, subalpine conifers experience frequent freeze-thaw cycles in stem xylem that may cause embolism and pit aspiration due to increased water volume during the sap to ice transition. This study examined the occurrence and ecological impacts of a combination of freeze-thaw-induced pit aspiration and embolism triggered by natural and artificial stem freezing. In subalpine Veitch's fir (Abies veitchii) trees, the fraction of closed pits and embolized tracheids as well as conductivity losses were measured to examine pit aspiration and its effects. When trees incurred mild drought stress in February and early March, 70%-80% of stem conductivity was lost. Cryo-scanning electron microscopy indicated <20% embolized tracheids but ∼90% closed pits. Severe drought stress in late March caused 96% ± 1.2% (mean ± standard error) loss of stem conductivity, while the fraction of embolized tracheids increased to 64% ± 6.6%, and aspirated pit fraction decreased to 23% ± 5.6%. Experimental freeze-thaw cycles also increased pit aspiration from 7.1% ± 0.89% to 49% ± 10%, and the fraction of closed pits was positively correlated to the percent loss of stem hydraulic conductivity. The results indicated that freezing-induced pit aspiration is an important factor for stem xylem dysfunction under mild drought, and upon severe drought in winter; stem water transport is predominantly inhibited by xylem embolism.
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Affiliation(s)
- Haruhiko Taneda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Mayumi Y Ogasa
- Forest Ecology Group, Kansai Research Center, Forestry and Forest Products Research Institute, Kyoto, Japan
| | - Kenichi Yazaki
- Soil-Plant Ecosystem Group, Hokkaido Research Center, Forestry and Forest Products Research Institute, Sapporo, Japan
| | - Sachiko Funayama-Noguchi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | | | - Stefan Mayr
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Emiko Maruta
- Department of Biological Sciences, Faculty of Science, Kanagawa University, Yokohama, Japan
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3
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Ganthaler A, Bär A, Dämon B, Losso A, Nardini A, Dullin C, Tromba G, von Arx G, Mayr S. Alpine dwarf shrubs show high proportions of nonfunctional xylem: Visualization and quantification of species-specific patterns. PLANT, CELL & ENVIRONMENT 2022; 45:55-68. [PMID: 34783044 DOI: 10.1111/pce.14226] [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: 04/13/2021] [Revised: 07/15/2021] [Accepted: 07/15/2021] [Indexed: 06/13/2023]
Abstract
Xylem conductive capacity is a key determinant of plant hydraulic function and intimately linked to photosynthesis and productivity, but can be impeded by temporary or permanent conduit dysfunctions. Here we show that persistent xylem dysfunctions in unstressed plants are frequent in Alpine dwarf shrubs and occur in various but species-specific cross-sectional patterns. Combined synchrotron micro-computed tomography (micro-CT) imaging, xylem staining, and flow measurements in saturated samples of six widespread Ericaceae species evidence a high proportion (19%-50%) of hydraulically nonfunctional xylem areas in the absence of drought stress, with regular distribution of dysfunctions between or within growth rings. Dysfunctions were only partly reversible and reduced the specific hydraulic conductivity to 1.38 to 3.57 ×10-4 m2 s-1 MPa-1 . Decommission of inner growth rings was clearly related to stem age and a higher vulnerability to cavitation of older rings, while the high proportion of nonfunctional conduits in each annual ring needs further investigations. The lower the xylem fraction contributing to the transport function, the higher was the hydraulic efficiency of conducting xylem areas. Improved understanding of the functional lifespan of xylem elements and the prevalence and nature of dysfunctions is critical to correctly assess structure-function relationships and whole-plant hydraulic strategies.
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Affiliation(s)
- Andrea Ganthaler
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Andreas Bär
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Birgit Dämon
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Adriano Losso
- Department of Botany, University of Innsbruck, Innsbruck, Austria
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
| | - Andrea Nardini
- Dipartimento di Scienze della Vita, Università di Trieste, Trieste, Italy
| | - Christian Dullin
- Elettra-Sincrotrone Trieste, Basovizza, Italy
- Institute for Diagnostic and Interventional Radiology, University Medical Center, Göttingen, Germany
- Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
- Diagnostic and Interventional Radiology, University Hospital, Heidelberg, Germany
| | | | - Georg von Arx
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
| | - Stefan Mayr
- Department of Botany, University of Innsbruck, Innsbruck, Austria
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4
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Feng F, Losso A, Tyree M, Zhang S, Mayr S. Cavitation fatigue in conifers: a study on eight European species. PLANT PHYSIOLOGY 2021; 186:1580-1590. [PMID: 33905499 PMCID: PMC8260135 DOI: 10.1093/plphys/kiab170] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 03/27/2021] [Indexed: 06/12/2023]
Abstract
After drought-induced embolism and repair, tree xylem may be weakened against future drought events (cavitation fatigue). As there are few data on cavitation fatigue in conifers available, we quantified vulnerability curves (VCs) after embolism/repair cycles on eight European conifer species. We induced 50% and 100% loss of conductivity (LC) with a cavitron, and analyzed VCs. Embolism repair was obtained by vacuum infiltration. All species demonstrated complete embolism repair and a lack of any cavitation fatigue after 50% LC . After 100% LC, European larch (Larix decidua), stone pine (Pinus cembra), Norway spruce (Picea abies), and silver fir (Abies alba) remained unaffected, while mountain pine (Pinus mugo), yew (Taxus baccata), and common juniper (Juniperus communis) exhibited 0.4-0.9 MPa higher vulnerability to embolism. A small cavitation fatigue observed in Scots pine (Pinus sylvestris) was probably biased by incomplete embolism repair, as indicated by a correlation of vulnerability shifts and conductivity restoration. Our data demonstrate that cavitation fatigue in conifers is species-specific and depends on the intensity of preceding LC. The lack of fatigue effects after moderate LC, and relevant effects in only three species after high LC, indicate that conifers are relatively resistant against cavitation fatigue. This is remarkable considering the complex and delicate conifer pit architecture and may be important considering climate change projections.
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Affiliation(s)
- Feng Feng
- College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China
- Qinling National Forest Ecosystem Research Station, Huoditang, Ningshan, Shaanxi 711600, China
| | - Adriano Losso
- Department of Botany, University of Innsbruck, Innsbruck 6020, Austria
| | - Melvin Tyree
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
| | - Shuoxin Zhang
- College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China
- Qinling National Forest Ecosystem Research Station, Huoditang, Ningshan, Shaanxi 711600, China
| | - Stefan Mayr
- Department of Botany, University of Innsbruck, Innsbruck 6020, Austria
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Sasani N, Pâques LE, Boulanger G, Singh AP, Gierlinger N, Rosner S, Brendel O. Physiological and anatomical responses to drought stress differ between two larch species and their hybrid. TREES (BERLIN, GERMANY : WEST) 2021; 35:1467-1484. [PMID: 34720435 PMCID: PMC8550302 DOI: 10.1007/s00468-021-02129-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 04/07/2021] [Indexed: 06/13/2023]
Abstract
KEY MESSAGE Hybrid saplings were more reactive to soil water deficit than Japanese and European larch. European larch had hydraulically safer wood and anisohydric behavior, Japanese and hybrid larch showed isohydric strategy. ABSTRACT Deciduous larch species could be an alternative to evergreen conifers in reforestation, but little is known about drought sensitivity of their saplings. The effect of an experimental drought on hydraulics and quantitative wood anatomy was tested on saplings of European larch (EL, Larix decidua), Japanese larch (JL, Larix kaempferi) and their hybrid (HL). Across species, biomass, transpiration rate and relative water content were higher in controls than in drought stressed trees, but transpiration efficiency was lower. JL had the highest transpiration efficiency under drought, and EL the lowest, coinciding with slower growth of EL. Wood of EL formed before drought was hydraulically safer as shown by higher wall/lumen ratio and lower pit cavity area. EL neither had a significant increase in transpiration efficiency nor a reduction in transpiration rate under drought, suggesting that the stomata remained open under soil water deficit. HL saplings were the most reactive to water shortage, indicated by intra-annual density fluctuations and a decrease in relative water content of the sapwood. Significant reduction in transpiration by HL suggested a higher stomatal sensitivity, while the same leaf surface area was maintained and radial growth was still similar to its best parent, the JL. The latter showed a significantly lower leaf surface area under drought than controls. EL, with its hydraulically safer wood, followed an anisohydric behavior, while JL and HL revealed an isohydric strategy. Altogether, our results suggest species dependent acclimations to drought stress, whereby HL followed the strategy of JL rather than that of EL. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s00468-021-02129-4.
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Affiliation(s)
- Nadia Sasani
- Institute of Biophysics, University of Natural Resources and Life Sciences, Vienna, Austria
| | | | - Guillaume Boulanger
- Université de Lorraine, AgroParisTech, INRAE, UMR Silva, 54000 Nancy, France
| | - Adya P. Singh
- Institute of Biophysics, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Notburga Gierlinger
- Institute of Biophysics, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Sabine Rosner
- Institute of Botany, University of Natural Resources and Life Sciences, Gregor Mendel Strasse 33, 1180 Vienna, Austria
| | - Oliver Brendel
- Université de Lorraine, AgroParisTech, INRAE, UMR Silva, 54000 Nancy, France
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Walthert L, Ganthaler A, Mayr S, Saurer M, Waldner P, Walser M, Zweifel R, von Arx G. From the comfort zone to crown dieback: Sequence of physiological stress thresholds in mature European beech trees across progressive drought. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 753:141792. [PMID: 33207466 DOI: 10.1016/j.scitotenv.2020.141792] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 06/11/2023]
Abstract
Drought responses of mature trees are still poorly understood making it difficult to predict species distributions under a warmer climate. Using mature European beech (Fagus sylvatica L.), a widespread and economically important tree species in Europe, we aimed at developing an empirical stress-level scheme to describe its physiological response to drought. We analysed effects of decreasing soil and leaf water potential on soil water uptake, stem radius, native embolism, early defoliation and crown dieback with comprehensive measurements from overall nine hydrologically distinct beech stands across Switzerland, including records from the exceptional 2018 drought and the 2019/2020 post-drought period. Based on the observed responses to decreasing water potential we derived the following five stress levels: I (predawn leaf water potential >-0.4 MPa): no detectable hydraulic limitations; II (-0.4 to -1.3): persistent stem shrinkage begins and growth ceases; III (-1.3 to -2.1): onset of native embolism and defoliation; IV (-2.1 to -2.8): onset of crown dieback; V (<-2.8): transpiration ceases and crown dieback is >20%. Our scheme provides, for the first time, quantitative thresholds regarding the physiological downregulation of mature European beech trees under drought and therefore synthesises relevant and fundamental information for process-based species distribution models. Moreover, our study revealed that European beech is drought vulnerable, because it still transpires considerably at high levels of embolism and because defoliation occurs rather as a result of embolism than preventing embolism. During the 2018 drought, an exposure to the stress levels III-V of only one month was long enough to trigger substantial crown dieback in beech trees on shallow soils. On deep soils with a high water holding capacity, in contrast, water reserves in deep soil layers prevented drought stress in beech trees. This emphasises the importance to include local data on soil water availability when predicting the future distribution of European beech.
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Affiliation(s)
- Lorenz Walthert
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland.
| | - Andrea Ganthaler
- Department of Botany, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria
| | - Stefan Mayr
- Department of Botany, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria
| | - Matthias Saurer
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Peter Waldner
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Marco Walser
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Roman Zweifel
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Georg von Arx
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
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7
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Unterholzner L, Carrer M, Bär A, Beikircher B, Dämon B, Losso A, Prendin AL, Mayr S. Juniperus communis populations exhibit low variability in hydraulic safety and efficiency. TREE PHYSIOLOGY 2020; 40:1668-1679. [PMID: 32785622 DOI: 10.1093/treephys/tpaa103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 08/07/2020] [Indexed: 06/11/2023]
Abstract
The performance and distribution of woody species strongly depend on their adjustment to environmental conditions based on genotypic and phenotypic properties. Since more intense and frequent drought events are expected due to climate change, xylem hydraulic traits will play a key role under future conditions, and thus, knowledge of hydraulic variability is of key importance. In this study, we aimed to investigate the variability in hydraulic safety and efficiency of the conifer shrub Juniperus communis based on analyses along an elevational transect and a common garden approach. We studied (i) juniper plants growing between 700 and 2000 m a.s.l. Innsbruck, Austria, and (ii) plants grown in the Innsbruck botanical garden (Austria) from seeds collected at different sites across Europe (France, Austria, Ireland, Germany and Sweden). Due to contrasting environmental conditions at different elevation and provenance sites and the wide geographical study area, pronounced variation in xylem hydraulics was expected. Vulnerability to drought-induced embolisms (hydraulic safety) was assessed via the Cavitron and ultrasonic acoustic emission techniques, and the specific hydraulic conductivity (hydraulic efficiency) via flow measurements. Contrary to our hypothesis, relevant variability in hydraulic safety and efficiency was neither observed across elevations, indicating a low phenotypic variation, nor between provenances, despite expected genotypic differences. Interestingly, the provenance from the most humid and warmest site (Ireland) and the northernmost provenance (Sweden) showed the highest and the lowest embolism resistance, respectively. The hydraulic conductivity was correlated with plant height, which indicates that observed variation in hydraulic traits was mainly related to morphological differences between plants. We encourage future studies to underlie anatomical traits and the role of hydraulics for the broad ecological amplitude of J. communis.
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Affiliation(s)
| | - Marco Carrer
- Department TeSAF, Università degli Studi di Padova, Legnaro (PD) 35122, Italy
| | - Andreas Bär
- Institut für Botanik, Universität Innsbruck, Innsbruck 6020, Austria
| | | | - Birgit Dämon
- Institut für Botanik, Universität Innsbruck, Innsbruck 6020, Austria
| | - Adriano Losso
- Institut für Botanik, Universität Innsbruck, Innsbruck 6020, Austria
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW 2753, Australia
| | | | - Stefan Mayr
- Institut für Botanik, Universität Innsbruck, Innsbruck 6020, Austria
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Mayr S, Schmid P, Beikircher B, Feng F, Badel E. Die hard: timberline conifers survive annual winter embolism. THE NEW PHYTOLOGIST 2020; 226:13-20. [PMID: 31677276 PMCID: PMC7065000 DOI: 10.1111/nph.16304] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 10/27/2019] [Indexed: 05/02/2023]
Abstract
During winter, timberline trees are exposed to drought and frost, factors known to induce embolism. Studies indicated that conifers cope with winter embolism by xylem refilling. We analysed the loss of hydraulic conductivity (LC) in Picea abies branch xylem over 10 years, and correlated winter embolism to climate parameters. LC was investigated by direct X-ray micro-computer tomography (micro-CT) observations and potential cavitation fatigue by Cavitron measurements. Trees showed up to 100% winter embolism, whereby LC was highest, when climate variables indicated frost drought and likely freeze-thaw stress further increased LC. During summer, LC never exceeded 16%, due to hydraulic recovery. Micro-CT revealed homogenous embolism during winter and that recovery was based on xylem refilling. Summer samples exhibited lower LC in outermost compared to older tree rings, although no cavitation fatigue was detected. Long-term data and micro-CT observations demonstrate that timberline trees can survive annual cycles of pronounced winter-embolism followed by xylem refilling. Only a small portion of the xylem conductivity cannot be restored during the first year, while remaining conduits are refilled without fatigue during consecutive years. We identify important research topics to better understand the complex induction and repair of embolism at the timberline and its relevance to general plant hydraulics.
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Affiliation(s)
- Stefan Mayr
- Department of BotanyUniversity of InnsbruckSternwartestr. 156020InnsbruckAustria
| | - Peter Schmid
- Department of BotanyUniversity of InnsbruckSternwartestr. 156020InnsbruckAustria
| | - Barbara Beikircher
- Department of BotanyUniversity of InnsbruckSternwartestr. 156020InnsbruckAustria
| | - Feng Feng
- College of ForestryNorthwest A&F University3 Taicheng RdYangling712100ShaanxiChina
| | - Eric Badel
- INRA, PIAFUniversité Clermont AuvergneF‐63000Clermont–FerrandFrance
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9
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Baker KV, Tai X, Miller ML, Johnson DM. Six co-occurring conifer species in northern Idaho exhibit a continuum of hydraulic strategies during an extreme drought year. AOB PLANTS 2019; 11:plz056. [PMID: 31656556 PMCID: PMC6804486 DOI: 10.1093/aobpla/plz056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 09/02/2019] [Indexed: 06/10/2023]
Abstract
As growing seasons in the northwestern USA lengthen, on track with climate predictions, the mixed conifer forests that dominate this region will experience extended seasonal drought conditions. The year of 2015, which had the most extreme drought for the area on record, offered a potential analogue of future conditions. During this period, we measured the daily courses of water potential and gas exchange as well as the hydraulic conductivity and vulnerability to embolism of six dominant native conifer species, Abies grandis, Larix occidentalis, Pinus ponderosa, Pinus monticola, Pseudotsuga menziesii and Thuja occidentalis, to determine their responses to 5 months of record-low precipitation. The deep ash-capped soils of the region allowed gas exchange to continue without significant evidence of water stress for almost 2 months after the last rainfall event. Midday water potentials never fell below -2.2 MPa in the evergreen species and -2.7 MPa in the one deciduous species. Branch xylem was resistant to embolism, with P 50 values ranging from -3.3 to -7.0 MPa. Root xylem, however, was more vulnerable, with P 50 values from -1.3 to -4.6 MPa. With predawn water potentials as low as -1.3 MPa, the two Pinus species likely experienced declines in root hydraulic conductivity. Stomatal conductance of all six species was significantly responsive to vapour pressure only in the dry months (August-October), with no response evident in the wet months (June-July). While there were similarities among species, they exhibited a continuum of isohydry and safety margins. Despite the severity of this drought, all species were able to continue photosynthesis until mid-October, likely due to the mediating effects of the meter-deep, ash-capped silty-loam soils with large water storage capacity. Areas with these soil types, which are characteristic of much of the northwestern USA, could serve as refugia under drier and warmer future conditions.
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Affiliation(s)
- Kathryn V Baker
- Department of Forest, Rangeland and Fire Sciences, University of Idaho, Moscow, ID, USA
- Department of Environmental Science, Marist College, Poughkeepsie, NY, USA
| | - Xiaonan Tai
- Department of Geology and Geophysics, University of Utah, Salt Lake City, UT, USA
| | - Megan L Miller
- Department of Forest, Rangeland and Fire Sciences, University of Idaho, Moscow, ID, USA
| | - Daniel M Johnson
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, USA
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10
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Ganthaler A, Marx K, Beikircher B, Mayr S. Are hydraulic patterns of lianas different from trees? New insights from Hedera helix. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:2811-2822. [PMID: 30796444 PMCID: PMC6506770 DOI: 10.1093/jxb/erz071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 02/11/2019] [Indexed: 05/31/2023]
Abstract
Lianas form long and flexible but disproportionately narrow stems, and thus require particular strategies to maintain the integrity of xylem water transport and ensure supply to large crown areas. The hydraulic architecture of lianas and the respective within-plant coordination of transport efficiency and safety, and the underlying anatomical variations in xylem, are largely unexplored. We analysed Hedera helix, a liana widespread in European temperate forests, with respect to hydraulic and xylem anatomical variations between the main stem and branches, between juvenile and adult life phases, and along the vertical axis. Main stems were significantly less embolism resistant but exhibited a higher hydraulic conductivity than branches. In branches, the cell turgor loss point of leaves decreased, while the embolism resistance and conductivity of xylem, as well as conduit diameters, increased with height. High water-transport capacities allow ivy to compensate for the small cross-section of stems, while the limited resistance to drought-induced xylem dysfunction of the main stem is probably linked to conservative stomatal regulation. Pronounced differences in xylem anatomy, hydraulic efficiency, and safety between the main stem and branches and along the vertical axis are surprisingly similar to those of self-supporting plants, and indicate that the coordination of carbon and water economies requires similar internal adjustments in tall plants.
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Affiliation(s)
- Andrea Ganthaler
- Department of Botany, University of Innsbruck, Sternwartestrasse, Innsbruck, Austria
| | - Katharina Marx
- Department of Botany, University of Innsbruck, Sternwartestrasse, Innsbruck, Austria
| | - Barbara Beikircher
- Department of Botany, University of Innsbruck, Sternwartestrasse, Innsbruck, Austria
| | - Stefan Mayr
- Department of Botany, University of Innsbruck, Sternwartestrasse, Innsbruck, Austria
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11
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Beikircher B, Losso A, Gemassmer M, Jansen S, Mayr S. Does fertilization explain the extraordinary hydraulic behaviour of apple trees? JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:1915-1925. [PMID: 30793193 PMCID: PMC6436149 DOI: 10.1093/jxb/erz070] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 02/07/2019] [Indexed: 05/13/2023]
Abstract
Fertilization of woody plants plays a central role in agriculture and forestry, but little is known about how plant water relations are thereby affected. Here we investigated the impact of fertilization on tree hydraulics, and xylem and pit anatomy in the high-yield apple cultivars Golden and Red Delicious. In fertilized trees of Golden Delicious, specific hydraulic conductivity of branch xylem, hydraulic conductance of the root system, and maximum stomatal conductance increased considerably. In Red Delicious, differences between fertilized and control trees were less pronounced. In both cultivars, xylem embolism resistance of fertilized trees was significantly lower and stomatal closure occurred at lower water potentials. Furthermore, water potential at turgor loss point and osmotic potential at full saturation were higher and cell wall elasticity was lower in fertilized plants, suggesting reduced drought tolerance of leaves. Anatomical differences were observed regarding conduit diameters, cell wall reinforcement, pit membrane thickness, pit chamber depth, and stomatal pore length, with more pronounced differences in Golden Delicious. The findings reveal altered hydraulic behaviour in both apple cultivars upon fertilization. The increased vulnerability to hydraulic failure might pose a considerable risk for apple productivity under a changing climate, which should be considered for future cultivation and management practices.
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Affiliation(s)
- Barbara Beikircher
- University of Innsbruck, Institute of Botany, Sternwartestrasse, Innsbruck, Austria
| | - Adriano Losso
- University of Innsbruck, Institute of Botany, Sternwartestrasse, Innsbruck, Austria
| | - Marilena Gemassmer
- University of Innsbruck, Institute of Botany, Sternwartestrasse, Innsbruck, Austria
| | - Steven Jansen
- Ulm University, Institute of Systematic Botany and Ecology, Albert-Einstein-Allee, Ulm, Germany
| | - Stefan Mayr
- University of Innsbruck, Institute of Botany, Sternwartestrasse, Innsbruck, Austria
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12
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Prendin AL, Mayr S, Beikircher B, von Arx G, Petit G. Xylem anatomical adjustments prioritize hydraulic efficiency over safety as Norway spruce trees grow taller. TREE PHYSIOLOGY 2018; 38:1088-1097. [PMID: 29920598 DOI: 10.1093/treephys/tpy065] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 05/16/2018] [Indexed: 05/23/2023]
Abstract
As a tree grows taller, the increase in gravitational pressure and path length resistance results in lower water potentials at a given flow rate and higher carbon construction costs to transport a given amount of water to the leaves. We investigated how hydraulic safety and efficiency are coordinated under the constraints of higher cavitation risks and higher carbon construction costs with increasing tree height. We combined measurements of xylem tracheid anatomical traits with the vulnerability to drought-induced embolism and hydraulic conductivity of the apical shoots of 2- to 37-m tall Picea abies trees growing at two sites in the Dolomites (Italian Eastern Alps). We found that the theoretical hydraulic conductivity of the apical shoots increased with tree height at both sites (P < 0.001) as a result of an increase in either total tracheid number or mean hydraulic diameter. The xylem water potential inducing 50% loss of apical conductance significantly increased from small (-4.45 ± 0.20 MPa) to tall trees (-3.65 ± 0.03 MPa) (P = 0.007). The more conductive xylem at the treetop of taller trees allows the full compensation for the height-related hydraulic constraints and minimizes the additional carbon costs of transporting water over a longer path length. The corresponding increase in vulnerability to cavitation shows that hydraulic efficiency is prioritized over safety during height growth.
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Affiliation(s)
- Angela Luisa Prendin
- Department TeSAF-Department of Territorio e Sistemi Agro-Forestali, Università degli Studi di Padova, viale dell'Università 16, Legnaro (PD), Italy
| | - Stefan Mayr
- Institut für Botanik, Universität Innsbruck, Sternwartestraße 15, Innsbruck, Austria
| | - Barbara Beikircher
- Institut für Botanik, Universität Innsbruck, Sternwartestraße 15, Innsbruck, Austria
| | - Georg von Arx
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, Birmensdorf, Switzerland
- Climatic Change and Climate Impacts, Institute for Environmental Sciences, 66 Boulevard Carl-Vogt, Geneva, Switzerland
| | - Giai Petit
- Department TeSAF-Department of Territorio e Sistemi Agro-Forestali, Università degli Studi di Padova, viale dell'Università 16, Legnaro (PD), Italy
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13
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Zhang Y, Lamarque LJ, Torres-Ruiz JM, Schuldt B, Karimi Z, Li S, Qin DW, Bittencourt P, Burlett R, Cao KF, Delzon S, Oliveira R, Pereira L, Jansen S. Testing the plant pneumatic method to estimate xylem embolism resistance in stems of temperate trees. TREE PHYSIOLOGY 2018; 38:1016-1025. [PMID: 29474679 PMCID: PMC6025199 DOI: 10.1093/treephys/tpy015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 01/19/2018] [Accepted: 01/31/2018] [Indexed: 05/23/2023]
Abstract
Methods to estimate xylem embolism resistance generally rely on hydraulic measurements, which can be far from straightforward. Recently, a pneumatic method based on air flow measurements of terminal branch ends was proposed to construct vulnerability curves by linking the amount of air extracted from a branch with the degree of embolism. We applied this novel technique for 10 temperate tree species, including six diffuse, two ring-porous and two gymnosperm species, and compared the pneumatic curves with hydraulic ones obtained from either the flow-centrifuge or the hydraulic-bench dehydration method. We found that the pneumatic method provides a good estimate of the degree of xylem embolism for all angiosperm species. The xylem pressure at 50% and 88% loss of hydraulic conductivity (i.e., Ψ50 and Ψ88) based on the methods applied showed a strongly significant correlation for all eight angiosperms. However, the pneumatic method showed significantly reduced Ψ50 values for the two conifers. Our findings suggest that the pneumatic method could provide a fast and accurate approach for angiosperms due to its convenience and feasibility, at least within the range of embolism resistances covered by our samples.
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Affiliation(s)
- Ya Zhang
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, Ulm, Germany
| | - Laurent J Lamarque
- BIOGECO, INRA, University of Bordeaux, Pessac, France
- EGFV, INRA, University of Bordeaux, Villenave d’Ornon, France
| | | | - Bernhard Schuldt
- Albrecht-von-Haller-Institute for Plant Sciences, Göttingen University, Göttingen, Germany
| | - Zohreh Karimi
- Department of Biology, Faculty of Science, Golestan University, Gorgan, Iran
| | - Shan Li
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, Ulm, Germany
- Department of Wood Anatomy and Utilization, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing, PR China
| | - De-Wen Qin
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, PR China
| | - Paulo Bittencourt
- Department of Plant Biology, Institute of Biology, PO Box 6109, University of Campinas – UNICAMP, Campinas, SP, Brazil
| | - Régis Burlett
- BIOGECO, INRA, University of Bordeaux, Pessac, France
| | - Kun-Fang Cao
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, PR China
| | | | - Rafael Oliveira
- Department of Plant Biology, Institute of Biology, PO Box 6109, University of Campinas – UNICAMP, Campinas, SP, Brazil
| | - Luciano Pereira
- Department of Plant Biology, Institute of Biology, PO Box 6109, University of Campinas – UNICAMP, Campinas, SP, Brazil
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, Ulm, Germany
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14
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Bär A, Nardini A, Mayr S. Post-fire effects in xylem hydraulics of Picea abies, Pinus sylvestris and Fagus sylvatica. THE NEW PHYTOLOGIST 2018; 217:1484-1493. [PMID: 29193122 DOI: 10.1111/nph.14916] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/23/2017] [Indexed: 06/07/2023]
Abstract
Recent studies on post-fire tree mortality suggest a role for heat-induced alterations of the hydraulic system. We analyzed heat effects on xylem hydraulics both in the laboratory and at a forest site hit by fire. Stem vulnerability to drought-induced embolism and hydraulic conductivity were measured in Picea abies, Pinus sylvestris and Fagus sylvatica. Control branches were compared with samples experimentally exposed to 90°C or damaged by a natural forest fire. In addition, xylem anatomical changes were examined microscopically. Experimental heating caused structural changes in the xylem and increased vulnerability in all species. The largest shifts in vulnerability thresholds (1.3 MPa) were observed in P. sylvestris. F. sylvatica also showed heat-induced reductions (49%) in hydraulic conductivity. At the field site, increased vulnerability was observed in damaged branches of P. sylvestris and F. sylvatica, and the xylem of F. sylvatica was 39% less conductive in damaged than in undamaged branches. These results provide evidence for heat-induced impairment of tree hydraulics after fire. The effects recorded at the forest fire site corresponded to those obtained in laboratory experiments, and revealed pronounced hydraulic risks in P. sylvestris and F. sylvatica. Knowledge of species-specific hydraulic impairments induced by fire and heat is a prerequisite for accurate estimation of post-fire mortality risks.
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Affiliation(s)
- Andreas Bär
- Department of Botany, University of Innsbruck, Sternwartestraße 15, 6020, Innsbruck, Austria
| | - Andrea Nardini
- Department of Life Sciences, University of Trieste, Via L. Giorgieri 10, 34127, Trieste, Italy
| | - Stefan Mayr
- Department of Botany, University of Innsbruck, Sternwartestraße 15, 6020, Innsbruck, Austria
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15
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Tomasella M, Beikircher B, Häberle KH, Hesse B, Kallenbach C, Matyssek R, Mayr S. Acclimation of branch and leaf hydraulics in adult Fagus sylvatica and Picea abies in a forest through-fall exclusion experiment. TREE PHYSIOLOGY 2018; 38:198-211. [PMID: 29177459 DOI: 10.1093/treephys/tpx140] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 10/03/2017] [Indexed: 05/26/2023]
Abstract
Decreasing water availability due to climate change poses the question of whether and to what extent tree species are able to hydraulically acclimate and how hydraulic traits of stems and leaves are coordinated under drought. In a through-fall exclusion experiment, hydraulic acclimation was analyzed in a mixed forest stand of Fagus sylvatica L. and Picea abies (L.) Karst. In drought-stressed (TE, through-fall exclusion over 2 years) and control (CO) trees, hydraulic vulnerability was studied in branches as well as in leaves (F. sylvatica) and end-twigs (P. abies, entirely formed during the drought period) sampled at the same height in sun-exposed portions of the tree crown. In addition, relevant xylem anatomical traits and leaf pressure-volume relations were analyzed. The TE trees reached pre-dawn water potentials down to -1.6 MPa. In both species, water potentials at 50% loss of xylem hydraulic conductivity were ~0.4 MPa more negative in TE than in CO branches. Foliage hydraulic vulnerability (expressed as water potential at 50% loss of leaf/end-twig hydraulic conductance) and water potential at turgor loss point were also, respectively, 0.4 and 0.5 MPa lower in TE trees. Minor differences were observed in conduit mean hydraulic diameter and cell wall reinforcement. Our findings indicate significant and fast hydraulic acclimation under relatively mild drought in both tree species. Acclimation was well coordinated between branches and foliage, which might be essential for survival and productivity of mature trees under future drought periods.
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Affiliation(s)
- Martina Tomasella
- Department of Ecology and Ecosystem Management, Chair for Ecophysiology of Plants, Technical University of Munich, Hans-Carl-von-Carlowitz Platz 2, 85354 Freising, Germany
| | - Barbara Beikircher
- Department of Botany, University of Innsbruck, Sternwartestraße 15, 6020 Innsbruck, Austria
| | - Karl-Heinz Häberle
- Department of Ecology and Ecosystem Management, Chair for Ecophysiology of Plants, Technical University of Munich, Hans-Carl-von-Carlowitz Platz 2, 85354 Freising, Germany
| | - Benjamin Hesse
- Department of Ecology and Ecosystem Management, Chair for Ecophysiology of Plants, Technical University of Munich, Hans-Carl-von-Carlowitz Platz 2, 85354 Freising, Germany
| | - Christian Kallenbach
- Department of Ecology and Ecosystem Management, Chair for Ecophysiology of Plants, Technical University of Munich, Hans-Carl-von-Carlowitz Platz 2, 85354 Freising, Germany
| | - Rainer Matyssek
- Department of Ecology and Ecosystem Management, Chair for Ecophysiology of Plants, Technical University of Munich, Hans-Carl-von-Carlowitz Platz 2, 85354 Freising, Germany
| | - Stefan Mayr
- Department of Botany, University of Innsbruck, Sternwartestraße 15, 6020 Innsbruck, Austria
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16
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Martin-StPaul N, Delzon S, Cochard H. Plant resistance to drought depends on timely stomatal closure. Ecol Lett 2017; 20:1437-1447. [DOI: 10.1111/ele.12851] [Citation(s) in RCA: 357] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 07/04/2017] [Accepted: 08/17/2017] [Indexed: 12/17/2022]
Affiliation(s)
| | | | - Hervé Cochard
- Université Clermont-Auvergne; INRA; PIAF; 63000, Clermont-Ferrand France
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17
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Battipaglia G, Savi T, Ascoli D, Castagneri D, Esposito A, Mayr S, Nardini A. Effects of prescribed burning on ecophysiological, anatomical and stem hydraulic properties in Pinus pinea L. TREE PHYSIOLOGY 2016; 36:1019-1031. [PMID: 27178842 DOI: 10.1093/treephys/tpw034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 03/22/2016] [Indexed: 06/05/2023]
Abstract
Prescribed burning (PB) is a widespread management technique for wildfire hazard abatement. Understanding PB effects on tree ecophysiology is key to defining burn prescriptions aimed at reducing fire hazard in Mediterranean pine plantations, such as Pinus pinea L. stands. We assessed physiological responses of adult P. pinea trees to PB using a combination of dendroecological, anatomical, hydraulic and isotopic analyses. Tree-ring widths, xylem cell wall thickness, lumen area, hydraulic diameter and tree-ring δ(13)C and δ(18)O were measured in trees on burned and control sites. Vulnerability curves were elaborated to assess tree hydraulic efficiency or safety. Despite the relatively intense thermal treatment (the residence time of temperatures above 50 °C at the stem surface ranged between 242 and 2239 s), burned trees did not suffer mechanical damage to stems, nor significant reduction in radial growth. Moreover, the PB did not affect xylem structure and tree hydraulics. No variations in (13)C-derived water use efficiency were recorded. This confirmed the high resistance of P. pinea to surface fire at the stem base. However, burned trees showed consistently lower δ(18)O values in the PB year, as a likely consequence of reduced competition for water and nutrients due to the understory burning, which increased both photosynthetic activity and stomatal conductance. Our multi-approach analysis offers new perspectives on post-fire survival strategies of P. pinea in an environment where fires are predicted to increase in frequency and severity during the 21st century.
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Affiliation(s)
- Giovanna Battipaglia
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Second University of Naples, Via Vivaldi 43, 81100 Caserta, Italy Ecole Pratique des Hautes Etudes (PALECO EPHE), Centre for Bio-Archaeology and Ecology, Institut des Sciences de l'Evolution, University of Montpellier 2, F-34090 Montpellier, France CMCC, Euro-Mediterranean Center on Climate Change, via Augusto Imperatore 16, 73100 Lecce, Italy
| | - Tadeja Savi
- Department of Life Sciences, University of Trieste, Via L. Giorgieri 10, 34127 Trieste, Italy
| | - Davide Ascoli
- Department of Agricultural, Forest and Food Sciences, University of Torino, Largo Paolo Braccini 2, 10095 Grugliasco (TO), Italy
| | - Daniele Castagneri
- Department of Land, Environment, Agriculture and Forestry, University of Padua, Via dell'Università 16, 35020 Legnaro (PD), Italy
| | - Assunta Esposito
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Second University of Naples, Via Vivaldi 43, 81100 Caserta, Italy
| | - Stefan Mayr
- Institut für Botanik Universität Innsbruck, Sternwartestr. 15, 6020 Innsbruck, Austria
| | - Andrea Nardini
- Department of Life Sciences, University of Trieste, Via L. Giorgieri 10, 34127 Trieste, Italy
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18
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Pivovaroff AL, Burlett R, Lavigne B, Cochard H, Santiago LS, Delzon S. Testing the 'microbubble effect' using the Cavitron technique to measure xylem water extraction curves. AOB PLANTS 2016; 8:plw011. [PMID: 26903487 PMCID: PMC4804203 DOI: 10.1093/aobpla/plw011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 02/05/2016] [Indexed: 05/20/2023]
Abstract
Plant resistance to xylem cavitation is a major drought adaptation trait and is essential to characterizing vulnerability to climate change. Cavitation resistance can be determined with vulnerability curves. In the past decade, new techniques have increased the ease and speed at which vulnerability curves are produced. However, these new techniques are also subject to new artefacts, especially as related to long-vesselled species. We tested the reliability of the 'flow rotor' centrifuge technique, the so-called Cavitron, and investigated one potential mechanism behind the open vessel artefact in centrifuge-based vulnerability curves: the microbubble effect. The microbubble effect hypothesizes that microbubbles introduced to open vessels, either through sample flushing or injection of solution, travel by buoyancy or mass flow towards the axis of rotation where they artefactually nucleate cavitation. To test the microbubble effect, we constructed vulnerability curves using three different rotor sizes for five species with varying maximum vessel length, as well as water extraction curves that are constructed without injection of solution into the rotor. We found that the Cavitron technique is robust to measure resistance to cavitation in tracheid-bearing and short-vesselled species, but not for long-vesselled ones. Moreover, our results support the microbubble effect hypothesis as the major cause for the open vessel artefact in long-vesselled species.
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Affiliation(s)
- Alexandria L Pivovaroff
- La Kretz Center for California Conservation Science, University of California Los Angeles, Los Angeles, CA 90095, USA Université de Bordeaux, UMR BIOGECO, 33405 Talence, France Department of Botany and Plant Sciences, University of California Riverside, 2150 Batchelor Hall, Riverside, CA 92521, USA
| | - Régis Burlett
- Université de Bordeaux, UMR BIOGECO, 33405 Talence, France
| | - Bruno Lavigne
- Université de Bordeaux, UMR BIOGECO, 33405 Talence, France
| | - Hervé Cochard
- INRA, UMR 547 PIAF, Université Clermont Auvergne, 63100 Clermont-Ferrand, France
| | - Louis S Santiago
- Department of Botany and Plant Sciences, University of California Riverside, 2150 Batchelor Hall, Riverside, CA 92521, USA
| | - Sylvain Delzon
- Université de Bordeaux, UMR BIOGECO, 33405 Talence, France INRA, UMR 1202 BIOGECO, 33612 Cestas, France
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19
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Elevational trends in hydraulic efficiency and safety of Pinus cembra roots. Oecologia 2015; 180:1091-102. [PMID: 26678990 PMCID: PMC4943587 DOI: 10.1007/s00442-015-3513-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 11/17/2015] [Indexed: 11/25/2022]
Abstract
In alpine regions, elevational gradients in environmental parameters
are reflected by structural and functional changes in plant traits. Elevational
changes in plant water relations have also been demonstrated, but comparable
information on root hydraulics is generally lacking. We analyzed the hydraulic
efficiency (specific hydraulic conductivity ks, entire root system conductance KR) and vulnerability to drought-induced embolism (water
potential at 50 % loss of conductivity Ψ50) of the roots of Pinus
cembra trees growing along an elevational transect of 600 m. Hydraulic
parameters of the roots were compared with those of the stem and related to
anatomical traits {mean conduit diameter (d),
wall reinforcement [(t/b)2]}. We hypothesized that
temperature-related restrictions in root function would cause a progressive
limitation of hydraulic efficiency and safety with increasing elevation. We found
that both root ks and KR decreased from low (1600 m a.s.l.: ks
5.6 ± 0.7 kg m−1 s−1 MPa−1,
KR
0.049 ± 0.005 kg m−2 s −1 MPa−1)
to high elevation (2100 m a.s.l.: ks
4.2 ± 0.6 kg m−1 s−1 MPa−1,
KR
0.035 ± 0.006 kg m−2 s−1 MPa−1),
with small trees showing higher KR than large trees. ks was higher in roots than in stems
(0.5 ± 0.05 kg m−1s−1MPa−1).
Ψ50 values were similar across elevations and overall less
negative in roots (Ψ50 −3.6 ± 0.1 MPa) than in stems (Ψ50 −3.9 ± 0.1 MPa). In roots, large-diameter tracheids were
lacking at high elevation and (t/b)2 increased, while d did not change. The elevational decrease in root
hydraulic efficiency reflects a limitation in timberline tree hydraulics. In
contrast, hydraulic safety was similar across elevations, indicating that avoidance
of hydraulic failure is important for timberline trees. As hydraulic patterns can
only partly be explained by the anatomical parameters studied, limitations and/or
adaptations at the pit level are likely.
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20
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Nolf M, Beikircher B, Rosner S, Nolf A, Mayr S. Xylem cavitation resistance can be estimated based on time-dependent rate of acoustic emissions. THE NEW PHYTOLOGIST 2015; 208:625-32. [PMID: 26010417 PMCID: PMC4744691 DOI: 10.1111/nph.13476] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 04/22/2015] [Indexed: 05/05/2023]
Abstract
Acoustic emission (AE) analysis allows nondestructive monitoring of embolism formation in plant xylem, but signal interpretation and agreement of acoustically measured hydraulic vulnerability with reference hydraulic techniques remain under debate. We compared the hydraulic vulnerability of 16 species and three crop tree cultivars using hydraulic flow measurements and acoustic emission monitoring, proposing the use of time-dependent AE rates as a novel parameter for AE analysis. There was a linear correlation between the water potential (Ψ) at 50% loss of hydraulic conductivity (P50 ) and the Ψ at maximum AE activity (Pmaxrate ), where species with lower P50 also had lower Pmaxrate (P < 0.001, R(2) = 0.76). Using AE rates instead of cumulative counts for AE analysis allows more efficient estimation of P50 , while excluding problematic AE at late stages of dehydration.
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Affiliation(s)
- Markus Nolf
- Institute of BotanyUniversity of InnsbruckSternwartestr. 15Innsbruck6020Austria
- Hawkesbury Institute for the EnvironmentUniversity of Western SydneyRichmondNSW2753Australia
| | - Barbara Beikircher
- Institute of BotanyUniversity of InnsbruckSternwartestr. 15Innsbruck6020Austria
| | - Sabine Rosner
- Institute of BotanyBOKU ViennaGregor Mendel Str. 33Vienna1180Austria
| | - Anton Nolf
- Institute for Experimental PhysicsUniversity of InnsbruckTechnikerstr. 25Innsbruck6020Austria
| | - Stefan Mayr
- Institute of BotanyUniversity of InnsbruckSternwartestr. 15Innsbruck6020Austria
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21
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Mayr S, Bertel C, Dämon B, Beikircher B. Static and dynamic bending has minor effects on xylem hydraulics of conifer branches (Picea abies, Pinus sylvestris). PLANT, CELL & ENVIRONMENT 2014; 37:2151-7. [PMID: 24697679 PMCID: PMC4312774 DOI: 10.1111/pce.12307] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/06/2014] [Accepted: 02/08/2014] [Indexed: 05/16/2023]
Abstract
The xylem hydraulic efficiency and safety is usually measured on mechanically unstressed samples, although trees may be exposed to combined hydraulic and mechanical stress in the field. We analysed changes in hydraulic conductivity and vulnerability to drought-induced embolism during static bending of Picea abies and Pinus sylvestris branches as well as the effect of dynamic bending on the vulnerability. We hypothesized this mechanical stress to substantially impair xylem hydraulics. Intense static bending caused an only small decrease in hydraulic conductance (-19.5 ± 2.4% in P. abies) but no shift in vulnerability thresholds. Dynamic bending caused a 0.4 and 0.8 MPa decrease of the water potential at 50 and 88% loss of conductivity in P. sylvestris, but did not affect vulnerability thresholds in P. abies. With respect to applied extreme bending radii, effects on plant hydraulics were surprisingly small and are thus probably of minor eco-physiological importance. More importantly, results indicate that available xylem hydraulic analyses (of conifers) sufficiently reflect plant hydraulics under field conditions.
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Affiliation(s)
- Stefan Mayr
- Department of Botany, University of Innsbruck, Sternwartestr. 15, A-6020, Innsbruck, Austria
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22
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Charra-Vaskou K, Badel E, Burlett R, Cochard H, Delzon S, Mayr S. Hydraulic efficiency and safety of vascular and non-vascular components in Pinus pinaster leaves. TREE PHYSIOLOGY 2012; 32:1161-1170. [PMID: 22907978 DOI: 10.1093/treephys/tps071] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Leaves, the distal section of the soil-plant-atmosphere continuum, exhibit the lowest water potentials in a plant. In contrast to angiosperm leaves, knowledge of the hydraulic architecture of conifer needles is scant. We investigated the hydraulic efficiency and safety of Pinus pinaster needles, comparing different techniques. The xylem hydraulic conductivity (k(s)) and embolism vulnerability (P(50)) of both needle and stem were measured using the cavitron technique. The conductance and vulnerability of whole needles were measured via rehydration kinetics, and Cryo-SEM and 3D X-ray microtomographic observations were used as reference tools to validate physical measurements. The needle xylem of P. pinaster had lower hydraulic efficiency (k(s) = 2.0 × 10(-4) m(2) MPa(-1) s(-1)) and safety (P(50) = - 1.5 MPa) than stem xylem (k(s) = 7.7 × 10(-4) m(2) MPa(-1) s(-1); P(50) = - 3.6 to - 3.2 MPa). P(50) of whole needles (both extra-vascular and vascular pathways) was - 0.5 MPa, suggesting that non-vascular tissues were more vulnerable than the xylem. During dehydration to - 3.5 MPa, collapse and embolism in xylem tracheids, and gap formation in surrounding tissues were observed. However, a discrepancy in hydraulic and acoustic results appeared compared with visualizations, arguing for greater caution with these techniques when applied to needles. Our results indicate that the most distal parts of the water transport pathway are limiting for hydraulics of P. pinaster. Needle tissues exhibit a low hydraulic efficiency and low hydraulic safety, but may also act to buffer short-term water deficits, thus preventing xylem embolism.
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Affiliation(s)
- Katline Charra-Vaskou
- Department of Botany, University of Innsbruck, Sternwartestr. 15, A-6020 Innsbruck, Austria.
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Melcher PJ, Michele Holbrook N, Burns MJ, Zwieniecki MA, Cobb AR, Brodribb TJ, Choat B, Sack L. Measurements of stem xylem hydraulic conductivity in the laboratory and field. Methods Ecol Evol 2012. [DOI: 10.1111/j.2041-210x.2012.00204.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Nardini A, Salleo S, Jansen S. More than just a vulnerable pipeline: xylem physiology in the light of ion-mediated regulation of plant water transport. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:4701-18. [PMID: 21765173 DOI: 10.1093/jxb/err208] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Major restrictions to the hydraulic conductance of xylem (K(XYL)) in vascular plants have traditionally been attributed to anatomical constraints. More recently, changes in the cationic concentration of xylem sap have been suggested to be responsible for short-term changes in K(XYL) based on data for 35 dicot species, and very few gymnosperms and ferns, indicating that xylem water transport may no longer be considered as an entirely passive process. Recent studies have revealed that this so-called ionic effect: (i) varies from little or no increase to >30%, (ii) is species specific, (iii) changes on a seasonal basis, (iv) depends on the cationic concentration, (v) is enhanced in embolized stems, and (vi) is positively correlated with vessel grouping. Furthermore, the ionic effect has been suggested to play functional roles in planta with respect to: (i) phloem-mediated control of xylem hydraulic properties, (ii) compensation of cavitation-induced loss of hydraulic conductance, with the result of optimizing light and water utilization, and (iii) differential regulation of water delivery to branches exposed to different levels of light. Pits are likely to play a key role in the ionic effect, which has largely been explained as a consequence of the poly-electrolytic nature and hydrogel properties of the pectic matrix of interconduit pit membranes, despite little evidence that pit membrane pectins remain present after cell hydrolysis. More research is needed to address the ionic effect in more species, physico-chemical properties of pit membranes, and how the ionic effect may increase xylem hydraulic conductance 'on demand'.
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Affiliation(s)
- Andrea Nardini
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, Italia.
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