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Bartholomé J, Mabiala A, Burlett R, Bert D, Leplé JC, Plomion C, Gion JM. The pulse of the tree is under genetic control: eucalyptus as a case study. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:338-356. [PMID: 32142191 DOI: 10.1111/tpj.14734] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 01/16/2020] [Accepted: 02/17/2020] [Indexed: 06/10/2023]
Abstract
The pulse of the tree (diurnal cycle of stem radius fluctuations) has been widely studied as a way of analyzing tree responses to the environment, including the phenotypic plasticity of tree-water relationships in particular. However, the genetic basis of this daily phenotype and its interplay with the environment remain largely unexplored. We characterized the genetic and environmental determinants of this response, by monitoring daily stem radius fluctuation (dSRF) on 210 trees from a Eucalyptus urophylla × E. grandis full-sib family over 2 years. The dSRF signal was broken down into hydraulic capacitance, assessed as the daily amplitude of shrinkage (DA), and net growth, estimated as the change in maximum radius between two consecutive days (ΔR). The environmental determinants of these two traits were clearly different: DA was positively correlated with atmospheric variables relating to water demand, while ΔR was associated with soil water content. The heritability for these two traits ranged from low to moderate over time, revealing a time-dependent or environment-dependent complex genetic determinism. We identified 686 and 384 daily quantitative trait loci (QTL) representing 32 and 31 QTL regions for DA and ΔR, respectively. The identification of gene networks underlying the 27 major genomics regions for both traits generated additional hypotheses concerning the biological mechanisms involved in response to water demand and supply. This study highlights that environmentally induced changes in daily stem radius fluctuation are genetically controlled in trees and suggests that these daily responses integrated over time shape the genetic architecture of mature traits.
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Affiliation(s)
- Jérôme Bartholomé
- BIOGECO, INRAE, University of Bordeaux, 33610, Cestas, France
- CIRAD, UMR AGAP, F-34398, Montpellier, France
- AGAP, University of Montpellier, CIRAD, INRA, Montpellier SupAgro, Montpellier, France
| | | | - Régis Burlett
- BIOGECO, INRAE, University of Bordeaux, 33610, Cestas, France
| | - Didier Bert
- BIOGECO, INRAE, University of Bordeaux, 33610, Cestas, France
| | | | | | - Jean-Marc Gion
- BIOGECO, INRAE, University of Bordeaux, 33610, Cestas, France
- CIRAD, UMR AGAP, F-34398, Montpellier, France
- AGAP, University of Montpellier, CIRAD, INRA, Montpellier SupAgro, Montpellier, France
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102
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Dayer S, Scharwies JD, Ramesh SA, Sullivan W, Doerflinger FC, Pagay V, Tyerman SD. Comparing Hydraulics Between Two Grapevine Cultivars Reveals Differences in Stomatal Regulation Under Water Stress and Exogenous ABA Applications. FRONTIERS IN PLANT SCIENCE 2020; 11:705. [PMID: 32636852 PMCID: PMC7316991 DOI: 10.3389/fpls.2020.00705] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 05/05/2020] [Indexed: 05/23/2023]
Abstract
Hydraulics of plants that have different strategies of stomatal regulation under water stress are relatively poorly understood. We explore how root and shoot hydraulics, stomatal conductance (g s), leaf and root aquaporin (AQP) expression, and abscisic acid (ABA) concentration in leaf xylem sap ([ABA]xylemsap) may be coordinated under mild water stress and exogenous ABA applications in two Vitis vinifera L. cultivars traditionally classified as near-isohydric (Grenache) and near-anisohydric (Syrah). Under water stress, Grenache exhibited stronger adjustments of plant and root hydraulic conductances and greater stomatal sensitivity to [ABA]xylemsap than Syrah resulting in greater conservation of soil moisture but not necessarily more isohydric behavior. Correlations between leaf (Ψleaf) and predawn (ΨPD) water potentials between cultivars suggested a "hydrodynamic" behavior rather than a particular iso-anisohydric classification. A significant decrease of Ψleaf in well-watered ABA-fed vines supported a role of ABA in the soil-leaf hydraulic pathway to regulate g s. Correlations between leaf and root AQPs expression levels under water deficit could explain the response of leaf (K leaf) and root (Lp r) hydraulic conductances in both cultivars. Additional studies under a wider range of soil water deficits are required to explore the possible differential regulation of g s and plant hydraulics in different cultivars and experimental conditions.
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Affiliation(s)
- Silvina Dayer
- School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, SA, Australia
| | - Johannes D. Scharwies
- School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, SA, Australia
| | - Sunita A. Ramesh
- School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, SA, Australia
| | - Wendy Sullivan
- School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, SA, Australia
| | | | - Vinay Pagay
- School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, SA, Australia
| | - Stephen D. Tyerman
- School of Agriculture, Food and Wine, The University of Adelaide, Glen Osmond, SA, Australia
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute, School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, SA, Australia
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103
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Jiang P, Meinzer FC, Wang H, Kou L, Dai X, Fu X. Below-ground determinants and ecological implications of shrub species' degree of isohydry in subtropical pine plantations. THE NEW PHYTOLOGIST 2020; 226:1656-1666. [PMID: 32096212 DOI: 10.1111/nph.16502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 02/16/2020] [Indexed: 06/10/2023]
Abstract
The degree of plant iso/anisohydry is a popular framework for characterising species-specific drought responses. However, we know little about associations between below-ground and above-ground hydraulic traits as well as the broader ecological implications of this framework. For 24 understory shrub species in seasonally dry subtropical coniferous plantations, we investigated contributions of the degree of isohydry to species' resource economy strategies, abundance, and importance value, and quantified the hydraulic conductance (Kh ) of above-ground and below-ground organs, magnitude of deep water acquisition (WAdeep ), shallow absorptive root traits (diameter, specific root length, tissue density), and resource-use efficiencies (Amax , maximum photosynthesis rate; PNUE, photosynthetic nitrogen-use efficiency). The extreme isohydric understory species had lower wood density (a proxy for higher growth rates) because their higher WAdeep and whole-plant Kh allowed higher Amax and PNUE, and thus did not necessarily show lower abundance and importance values. Although species' Kh was coordinated with their water foraging capacity in shallow soil, the more acquisitive deep roots were more crucial than shallow roots in shaping species' extreme isohydric behaviour. Our results provide new insights into the mechanisms through which below-ground hydraulic traits, especially those of deep roots, determine species' degree of isohydry and economic strategies.
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Affiliation(s)
- Peipei Jiang
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modelling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Frederick C Meinzer
- USDA Forest Service, Pacific Northwest Research Station, 3200 SW Jefferson Way, Corvallis, OR, 97331, USA
| | - Huimin Wang
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modelling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Liang Kou
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modelling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Xiaoqin Dai
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modelling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Xiaoli Fu
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modelling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100190, China
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104
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Grossiord C, Buckley TN, Cernusak LA, Novick KA, Poulter B, Siegwolf RTW, Sperry JS, McDowell NG. Plant responses to rising vapor pressure deficit. THE NEW PHYTOLOGIST 2020; 226:1550-1566. [PMID: 32064613 DOI: 10.1111/nph.16485] [Citation(s) in RCA: 337] [Impact Index Per Article: 84.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 02/04/2020] [Indexed: 05/24/2023]
Abstract
Recent decades have been characterized by increasing temperatures worldwide, resulting in an exponential climb in vapor pressure deficit (VPD). VPD has been identified as an increasingly important driver of plant functioning in terrestrial biomes and has been established as a major contributor in recent drought-induced plant mortality independent of other drivers associated with climate change. Despite this, few studies have isolated the physiological response of plant functioning to high VPD, thus limiting our understanding and ability to predict future impacts on terrestrial ecosystems. An abundance of evidence suggests that stomatal conductance declines under high VPD and transpiration increases in most species up until a given VPD threshold, leading to a cascade of subsequent impacts including reduced photosynthesis and growth, and higher risks of carbon starvation and hydraulic failure. Incorporation of photosynthetic and hydraulic traits in 'next-generation' land-surface models has the greatest potential for improved prediction of VPD responses at the plant- and global-scale, and will yield more mechanistic simulations of plant responses to a changing climate. By providing a fully integrated framework and evaluation of the impacts of high VPD on plant function, improvements in forecasting and long-term projections of climate impacts can be made.
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Affiliation(s)
- Charlotte Grossiord
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903, Birmensdorf, Switzerland
- École Polytechnique Fédérale de Lausanne EPFL, School of Architecture, Civil and Environmental Engineering ENAC, 1015, Lausanne, Switzerland
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, Davis, CA, 95616, USA
| | - Lucas A Cernusak
- College of Science and Engineering, James Cook University, Cairns, Qld, 4814, Australia
| | - Kimberly A Novick
- School of Public and Environmental Affairs, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - Benjamin Poulter
- Biospheric Sciences Lab, NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA
| | - Rolf T W Siegwolf
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903, Birmensdorf, Switzerland
| | - John S Sperry
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA
| | - Nate G McDowell
- Earth Systems Science Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
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105
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Eller CB, Rowland L, Mencuccini M, Rosas T, Williams K, Harper A, Medlyn BE, Wagner Y, Klein T, Teodoro GS, Oliveira RS, Matos IS, Rosado BHP, Fuchs K, Wohlfahrt G, Montagnani L, Meir P, Sitch S, Cox PM. Stomatal optimization based on xylem hydraulics (SOX) improves land surface model simulation of vegetation responses to climate. THE NEW PHYTOLOGIST 2020; 226:1622-1637. [PMID: 31916258 PMCID: PMC7318565 DOI: 10.1111/nph.16419] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 01/03/2020] [Indexed: 05/23/2023]
Abstract
Land surface models (LSMs) typically use empirical functions to represent vegetation responses to soil drought. These functions largely neglect recent advances in plant ecophysiology that link xylem hydraulic functioning with stomatal responses to climate. We developed an analytical stomatal optimization model based on xylem hydraulics (SOX) to predict plant responses to drought. Coupling SOX to the Joint UK Land Environment Simulator (JULES) LSM, we conducted a global evaluation of SOX against leaf- and ecosystem-level observations. SOX simulates leaf stomatal conductance responses to climate for woody plants more accurately and parsimoniously than the existing JULES stomatal conductance model. An ecosystem-level evaluation at 70 eddy flux sites shows that SOX decreases the sensitivity of gross primary productivity (GPP) to soil moisture, which improves the model agreement with observations and increases the predicted annual GPP by 30% in relation to JULES. SOX decreases JULES root-mean-square error in GPP by up to 45% in evergreen tropical forests, and can simulate realistic patterns of canopy water potential and soil water dynamics at the studied sites. SOX provides a parsimonious way to incorporate recent advances in plant hydraulics and optimality theory into LSMs, and an alternative to empirical stress factors.
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Affiliation(s)
- Cleiton B. Eller
- College of Life and Environmental SciencesUniversity of ExeterExeterEX4 4QFUK
- Department of Plant BiologyUniversity of CampinasCampinas13083‐862Brazil
| | - Lucy Rowland
- College of Life and Environmental SciencesUniversity of ExeterExeterEX4 4QFUK
| | - Maurizio Mencuccini
- CREAFBellaterra08193BarcelonaSpain
- ICREAPg. Lluís Companys 2308010BarcelonaSpain
| | - Teresa Rosas
- CREAFBellaterra08193BarcelonaSpain
- ICREAPg. Lluís Companys 2308010BarcelonaSpain
| | | | - Anna Harper
- College of Engineering, Mathematics and Physical SciencesUniversity of ExeterExeterEX4 4QFUK
| | - Belinda E. Medlyn
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityLocked Bag 1797PenrithNSW2751Australia
| | - Yael Wagner
- Department of Plant & Environmental SciencesWeizmann Institute of Science76100RehovotIsrael
| | - Tamir Klein
- Department of Plant & Environmental SciencesWeizmann Institute of Science76100RehovotIsrael
| | | | - Rafael S. Oliveira
- Department of Plant BiologyUniversity of CampinasCampinas13083‐862Brazil
| | - Ilaine S. Matos
- Department of Ecology – IBRAGRio de Janeiro State University (UERJ)Rio de Janeiro20550‐013Brazil
| | - Bruno H. P. Rosado
- Department of Ecology – IBRAGRio de Janeiro State University (UERJ)Rio de Janeiro20550‐013Brazil
| | - Kathrin Fuchs
- Department of Environmental Systems ScienceETH ZurichUniversitätstrasse 28092ZurichSwitzerland
| | - Georg Wohlfahrt
- Department of EcologyUniversity of InnsbruckInnsbruck6020Austria
| | - Leonardo Montagnani
- Forest ServicesAutonomous Province of BolzanoVia Brennero 639100BolzanoItaly
| | - Patrick Meir
- Research School of BiologyThe Australian National UniversityActonACT2601Australia
- School of GeosciencesUniversity of EdinburghEdinburghEH9 3FFUK
| | - Stephen Sitch
- College of Life and Environmental SciencesUniversity of ExeterExeterEX4 4QFUK
| | - Peter M. Cox
- College of Engineering, Mathematics and Physical SciencesUniversity of ExeterExeterEX4 4QFUK
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106
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Merlaen B, De Keyser E, Van Labeke MC. The jasmonic acid pathway, rather than abscisic acid, may partly explain contrasting stomatal responses in two strawberry cultivars under osmotic stress. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2020; 151:21-33. [PMID: 32179469 DOI: 10.1016/j.plaphy.2020.02.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/02/2020] [Accepted: 02/26/2020] [Indexed: 05/15/2023]
Abstract
Drought is a major threat in agriculture and horticulture, including commercial strawberry production. Here, we compare hormonal regulation of a first-line drought stress response, namely stomatal closure, in two Fragaria x ananassa cultivars, known to differ in their drought stress phenotype. We show that the observed difference in xylem abscisic acid accumulation cannot explain the different stomatal responses under osmotic stress. Foliar abscisic acid accumulation cannot fully account for the stomatal behavior in one of both cultivars either. An indirect effect of abscisic acid on stomatal conductance via an impact on leaf hydraulic conductance, possibly mediated via aquaporins, as is recently proposed in literature, was not observed here. Next, we show that these two cultivars respond differently to jasmonic acid and one of its precursors. This difference in sensitivity of the jasmonates pathway between both cultivars may partly explain the different stomatal response. This study contributes to the understanding of the regulation of an important drought stress response in an economically important crop prone to water deficit stress.
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Affiliation(s)
- Britt Merlaen
- Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Gent, Belgium.
| | - Ellen De Keyser
- Plant Sciences Unit, Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Caritasstraat 39, 9090, Melle, Belgium.
| | - Marie-Christine Van Labeke
- Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Gent, Belgium.
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107
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Medina-Villar S, Uscola M, Pérez-Corona ME, Jacobs DF. Environmental stress under climate change reduces plant performance, yet increases allelopathic potential of an invasive shrub. Biol Invasions 2020. [DOI: 10.1007/s10530-020-02286-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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108
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Lanning M, Wang L, Novick KA. The importance of cuticular permeance in assessing plant water-use strategies. TREE PHYSIOLOGY 2020; 40:425-432. [PMID: 32091105 DOI: 10.1093/treephys/tpaa020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 01/20/2020] [Accepted: 02/22/2020] [Indexed: 06/10/2023]
Abstract
Accurate understanding of plant responses to water stress is increasingly important for quantification of ecosystem carbon and water cycling under future climates. Plant water-use strategies can be characterized across a spectrum of water stress responses, from tight stomatal control (isohydric) to distinctly less stomatal control (anisohydric). A recent and popular classification method of plant water-use strategies utilizes the regression slope of predawn and midday leaf water potentials, σ, to reflect the coupling of soil water availability (predawn leaf water potential) and stomatal dynamics (daily decline in leaf water potential). This type of classification is important in predicting ecosystem drought response and resiliency. However, it fails to explain the relative stomatal responses to drought of Acer sacharrum and Quercus alba, improperly ranking them on the spectrum of isohydricity. We argue this inconsistency may be in part due to the cuticular conductance of different species. We used empirical and modeling evidence to show that plants with more permeable cuticles are more often classified as anisohydric; the σ values of those species were very well correlated with measured cuticular permeance. Furthermore, we found that midday leaf water potential in species with more permeable cuticles would continue to decrease as soils become drier, but not in those with less permeable cuticles. We devised a diagnostic parameter, Γ, to identify circumstances where the impact of cuticular conductance could cause species misclassification. The results suggest that cuticular conductance needs to be considered to better understand plant water-use strategies and to accurately predict forest responses to water stress under future climate scenarios.
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Affiliation(s)
- Matthew Lanning
- Department of Earth Science, Indiana University - Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Lixin Wang
- Department of Earth Science, Indiana University - Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202, USA
| | - Kimberly A Novick
- School of Public and Environmental Affairs, Indiana University Bloomington, 1315 East Tenth Street, Bloomington, IN 47405, USA
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109
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Differences in Near Isohydric and Anisohydric Behavior of Contrasting Poplar Hybrids (I-101 (Populus alba L.) × 84K (Populus alba L. × Populus glandulosa Uyeki)) under Drought-Rehydration Treatments. FORESTS 2020. [DOI: 10.3390/f11040402] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Carbon starvation and hydraulic failure are considered important factors in determining the mechanisms associated with tree mortality. In this study, iso/anisohydric classification was used to assess drought resistance and mortality mechanisms in two contrasting poplar species, as it is generally believed that isohydric species are more susceptible to carbon starvation, while anisohydric species are more susceptible to hydraulic failure. However, these assumptions are rarely tested in poplar genotypes with contrasting growth strategies. Thus, we subjected potted poplar genotypes (I-101 (Populus alba L.) × 84K (Populus alba L. × Populus glandulosa Uyeki)) with fast and slow growth rates to drought–rehydration treatments. The slow-growing genotype maintained higher stomatal conductance and lower predawn leaf water potential than the fast-growing genotype, thus exhibiting a near-anisohydric stomatal behavior throughout the treatment period. The nonstructural carbohydrate (NSC) content indicated that the two genotypes had the same trend of carbon change (e.g., the NSC content in the leaves increased with drought and then decreased). However, when NSC content data were combined with the growth and photosynthetic data, it was observed that the slow-growing genotype mobilized carbon to maintain hydraulic safety, while the NSC content of the fast-growing genotype among tissues was static. The percent loss of hydraulic conductivity in the branches during treatments indicated that the fast-growing genotype could recover more quickly from xylem embolism than the slow-growing genotype. The slow-growing genotype with a slow growth recovery after rehydration showed a significant increase in carbon consumption, combined with a significant increase in the hydraulic safety threshold value, indicating that there may be drought tolerance. In comparison, the fast-growing genotype showed a faster hydraulic recovery ability that had no effect on the NSC content in the leaves and roots. Our findings demonstrate intraspecific isohydric behavior in poplar; however, the trade-off between carbon distribution and stomatal regulation should be considered separately within genotypes of the same species. In addition, NSC plays an important role in water–carbon balance in the drought–rehydration cycle.
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110
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Väänänen PJ, Osem Y, Cohen S, Grünzweig JM. Differential drought resistance strategies of co-existing woodland species enduring the long rainless Eastern Mediterranean summer. TREE PHYSIOLOGY 2020; 40:305-320. [PMID: 31860712 DOI: 10.1093/treephys/tpz130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 08/28/2019] [Accepted: 09/17/2019] [Indexed: 06/10/2023]
Abstract
In anticipation of a drier climate and to project future changes in forest dynamics, it is imperative to understand species-specific differences in drought resistance. The objectives of this study were to form a comprehensive understanding of the drought resistance strategies adopted by Eastern Mediterranean woodland species, and to elaborate specific ecophysiological traits that can explain the observed variation in survival among these species. We examined leaf water potential (𝛹), gas exchange and stem hydraulics during 2-3 years in mature individuals of the key woody species Phillyrea latifolia L., Pistacia lentiscus L. and Quercus calliprinos Webb that co-exist in a dry woodland experiencing ~ 6 rainless summer months. As compared with the other two similarly functioning species, Phillyrea displayed considerably lower 𝛹 (minimum 𝛹 of -8.7 MPa in Phillyrea vs -4.2 MPa in Pistacia and Quercus), lower 𝛹 at stomatal closure and lower leaf turgor loss point (𝛹TLP ), but reduced hydraulic vulnerability and wider safety margins. Notably, Phillyrea allowed 𝛹 to drop below 𝛹TLP under severe drought, whereas the other two species maintained positive turgor. These results indicate that Phillyrea adopted a more anisohydric drought resistance strategy, while Pistacia and Quercus exhibited a more isohydric strategy and probably relied on deeper water reserves. Unlike the two relatively isohydric species, Phillyrea reached complete stomatal closure at the end of the dry summer. Despite assessing a large number of physiological traits, none of them could be directly related to tree mortality. Higher mortality was observed for Quercus than for the other two species, which may result from higher water consumption due to its 2.5-10 times larger crown volume. The observed patterns suggest that similar levels of drought resistance in terms of survival can be achieved via different drought resistance strategies. Conversely, similar resistance strategies in terms of isohydricity can lead to different levels of vulnerability to extreme drought.
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Affiliation(s)
- Päivi J Väänänen
- Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 7610001, Israel
- Department of Natural Resources, Agricultural Research Organization, Volcani Center, Bet-Dagan 50250, Israel
| | - Yagil Osem
- Department of Natural Resources, Agricultural Research Organization, Volcani Center, Bet-Dagan 50250, Israel
| | - Shabtai Cohen
- Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, Volcani Center, Bet-Dagan 50250, Israel
| | - 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, P.O. Box 12, Rehovot 7610001, Israel
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111
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Kannenberg SA, Phillips RP. Non-structural carbohydrate pools not linked to hydraulic strategies or carbon supply in tree saplings during severe drought and subsequent recovery. TREE PHYSIOLOGY 2020; 40:259-271. [PMID: 31860721 DOI: 10.1093/treephys/tpz132] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/30/2019] [Accepted: 11/16/2019] [Indexed: 06/10/2023]
Abstract
Non-structural carbohydrate (NSC) pools fluctuate based on the interplay between photosynthesis, demand from various carbon (C) sinks and tree hydraulic status. Thus, it has been hypothesized that tree species with isohydric stomatal control (i.e., trees that close stomata rapidly in response to drought) rely heavily on NSC pools to sustain metabolism, which can lead to negative physiological consequences such as C depletion. Here, we seek to use a species' degree of isohydry or anisohydry as a conceptual framework for understanding the interrelations between photosynthetic C supply, hydraulic damage and fluctuations in NSC pools. We conducted a 6-week experimental drought, followed by a 6-week recovery period, in a greenhouse on seven tree species that span the spectrum from isohydric to anisohydric. Throughout the experiment, we measured photosynthesis, hydraulic damage and NSC pools. Non-structural carbohydrate pools were remarkably stable across species and tissues-even highly isohydric species that drastically reduced C assimilation were able to maintain stored C. Despite these static NSC pools, we still inferred an important role for stored C during drought, as most species converted starches into sugars during water stress (and back again post-drought). Finally, we did not observe any linkages between C supply, hydraulic damage and NSC pools, indicating that NSC was maintained independent of variation in photosynthesis and hydraulic function. Our results advance the idea that C depletion is a rare phenomenon due to either active maintenance of NSC pools or sink limitation, and thus question the hypothesis that reductions in C assimilation necessarily lead to C depletion.
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Affiliation(s)
- Steven A Kannenberg
- School of Biological Sciences, University of Utah, 257 1400 East, Salt Lake City, UT 84112, USA
- Department of Biology, Indiana University, 1001 East 3rd Street, Bloomington, IN 47405, USA
| | - Richard P Phillips
- Department of Biology, Indiana University, 1001 East 3rd Street, Bloomington, IN 47405, USA
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112
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Torquato PR, Zou CB, Adhikari A, Adams HD, Will RE. Drought Tolerance and Competition in Eastern Redcedar ( Juniperus virginiana) Encroachment of the Oak-Dominated Cross Timbers. FRONTIERS IN PLANT SCIENCE 2020; 11:59. [PMID: 32117395 PMCID: PMC7020614 DOI: 10.3389/fpls.2020.00059] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 01/15/2020] [Indexed: 06/10/2023]
Abstract
On the dry, western edge of the eastern deciduous forest of the USA (Cross Timbers), the drought-tolerant, evergreen eastern redcedar (Juniperus virginiana) is encroaching into post oak- (Quercus stellata) dominated woodlands. The overall goal of this study was to examine whether the drought tolerance strategies of eastern redcedar provide it a competitive advantage over post oak and whether this is a key attribute facilitating its successful establishment in the Cross Timbers. Specifically, we assessed xylem water potential and leaf gas exchange of these two species growing in single-species stands and in a mixed-species stand. We found that both species exhibit a similar degree of isohydry and close their stomates to the same extent in response to declining xylem water potentials. Both species had similar relative reductions in gas exchange in response to drought, despite differences in xylem anatomy. However, post oak had leaf-level gas exchange rates approximately 5× greater than eastern redcedar during periods of high moisture availability. Therefore, it did not appear that eastern redcedar encroachment into an oak-dominated forest is facilitated by growing season differences in carbon gain, although evergreen eastern redcedar can conduct gas exchange year-round when conditions are favorable while post oak is deciduous. We found that volumetric soil water content (0-45 cm) was lower in the pure eastern redcedar stand than the mixed-species or pure post oak stand which may indicate that eastern redcedar may experience favorable soil moisture conditions when encroaching into open oak woodlands. Moreover, water potentials in eastern redcedar tended to be more negative in pure stands compared to the mixed stand. Our results suggest the two species may be using water from different depths, reducing competition. Overall, our findings indicate that eastern redcedar encroachment into formerly oak-dominated Cross Timbers forests likely will continue under moderate drought, in the absence of fire, with consequences for water budgets, carbon cycling, grazing forage, wildlife habitat, and wildfire risk.
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Affiliation(s)
- Patricia R. Torquato
- Department of Natural Resource Ecology and Management, Oklahoma State University, Stillwater, OK, United States
- School of Ecosystem and Forest Sciences, The University of Melbourne, Burnley, VIC, Australia
| | - Chris B. Zou
- Department of Natural Resource Ecology and Management, Oklahoma State University, Stillwater, OK, United States
| | - Arjun Adhikari
- Department of Natural Resource Ecology and Management, Oklahoma State University, Stillwater, OK, United States
| | - Henry D. Adams
- Department of Plant Biology, Ecology, and Evolution, Oklahoma State University, Stillwater, OK, United States
| | - Rodney E. Will
- Department of Natural Resource Ecology and Management, Oklahoma State University, Stillwater, OK, United States
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113
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Wu J, Serbin SP, Ely KS, Wolfe BT, Dickman LT, Grossiord C, Michaletz ST, Collins AD, Detto M, McDowell NG, Wright SJ, Rogers A. The response of stomatal conductance to seasonal drought in tropical forests. GLOBAL CHANGE BIOLOGY 2020; 26:823-839. [PMID: 31482618 DOI: 10.1111/gcb.14820] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 08/20/2019] [Indexed: 05/27/2023]
Abstract
Stomata regulate CO2 uptake for photosynthesis and water loss through transpiration. The approaches used to represent stomatal conductance (gs ) in models vary. In particular, current understanding of drivers of the variation in a key parameter in those models, the slope parameter (i.e. a measure of intrinsic plant water-use-efficiency), is still limited, particularly in the tropics. Here we collected diurnal measurements of leaf gas exchange and leaf water potential (Ψleaf ), and a suite of plant traits from the upper canopy of 15 tropical trees in two contrasting Panamanian forests throughout the dry season of the 2016 El Niño. The plant traits included wood density, leaf-mass-per-area (LMA), leaf carboxylation capacity (Vc,max ), leaf water content, the degree of isohydry, and predawn Ψleaf . We first investigated how the choice of four commonly used leaf-level gs models with and without the inclusion of Ψleaf as an additional predictor variable influence the ability to predict gs , and then explored the abiotic (i.e. month, site-month interaction) and biotic (i.e. tree-species-specific characteristics) drivers of slope parameter variation. Our results show that the inclusion of Ψleaf did not improve model performance and that the models that represent the response of gs to vapor pressure deficit performed better than corresponding models that respond to relative humidity. Within each gs model, we found large variation in the slope parameter, and this variation was attributable to the biotic driver, rather than abiotic drivers. We further investigated potential relationships between the slope parameter and the six available plant traits mentioned above, and found that only one trait, LMA, had a significant correlation with the slope parameter (R2 = 0.66, n = 15), highlighting a potential path towards improved model parameterization. This study advances understanding of gs dynamics over seasonal drought, and identifies a practical, trait-based approach to improve modeling of carbon and water exchange in tropical forests.
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Affiliation(s)
- Jin Wu
- Environmental & Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, USA
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong
| | - Shawn P Serbin
- Environmental & Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, USA
| | - Kim S Ely
- Environmental & Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, USA
| | - Brett T Wolfe
- Smithsonian Tropical Research Institute, Apartado, Panama
| | - L Turin Dickman
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Charlotte Grossiord
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Sean T Michaletz
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Adam D Collins
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Matteo Detto
- Smithsonian Tropical Research Institute, Apartado, Panama
- Ecology and Evolutionary Biology Department, Princeton University, Princeton, NJ, USA
| | - Nate G McDowell
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | | | - Alistair Rogers
- Environmental & Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, USA
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114
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Lu Y, Duursma RA, Farrior CE, Medlyn BE, Feng X. Optimal stomatal drought response shaped by competition for water and hydraulic risk can explain plant trait covariation. THE NEW PHYTOLOGIST 2020; 225:1206-1217. [PMID: 31538667 DOI: 10.1111/nph.16207] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 09/12/2019] [Indexed: 05/26/2023]
Abstract
The classical theory of stomatal optimization stipulates that stomata should act to maximize photosynthesis while minimizing transpiration. This theory, despite its remarkable success in reproducing empirical patterns, does not account for the fact that the available water to plants is dynamically regulated by plants themselves, and that plants compete for water in most locations. Here, we develop an alternative theory in which plants maximize the expected carbon gain under stochastic rainfall in a competitive environment. We further incorporate xylem hydraulic limitation as an additional constraint to transpiration and evaluate its impacts on stomatal optimization by incorporating the direct carbon cost of xylem recovery and the opportunity cost of reduced future photosynthesis as a result of irrecoverable xylem damage. We predict stomatal behaviour to be more conservative with a higher cost induced by xylem damage. By varying the unit carbon cost and extent of xylem recovery, characterizing the direct and opportunity cost of xylem damage, respectively, our model can reproduce several key patterns of stomatal-hydraulic trait covariations. By addressing the key elements of water limitation in plant gas exchange simultaneously, including plants' self-regulation of water availability, competition for water and hydraulic risk, our study provides a comprehensive theoretical basis for understanding stomatal behaviour.
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Affiliation(s)
- Yaojie Lu
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, 2751, NSW, Australia
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Twin Cities, MN, 55455, USA
| | - Remko A Duursma
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, 2751, NSW, Australia
| | - Caroline E Farrior
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Belinda E Medlyn
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, 2751, NSW, Australia
| | - Xue Feng
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Twin Cities, MN, 55455, USA
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115
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Carrière SD, Martin-StPaul NK, Cakpo CB, Patris N, Gillon M, Chalikakis K, Doussan C, Olioso A, Babic M, Jouineau A, Simioni G, Davi H. The role of deep vadose zone water in tree transpiration during drought periods in karst settings - Insights from isotopic tracing and leaf water potential. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 699:134332. [PMID: 31629315 DOI: 10.1016/j.scitotenv.2019.134332] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/04/2019] [Accepted: 09/05/2019] [Indexed: 06/10/2023]
Abstract
Karst environments are unusual because their dry, stony and shallow soils seem to be unfavorable to vegetation, and yet they are often covered with forests. How can trees survive in these environments? Where do they find the water that allows them to survive? This study uses midday and predawn water potentials and xylem water isotopes of branches to assess tree water status and the origin of transpired water. Monitoring was conducted during the summers of 2014 and 2015 in two dissimilar plots of Mediterranean forest located in karst environments. The results show that the three monitored tree species (Abies alba Mill, Fagus sylvatica L, and Quercus ilex L.) use deep water resources present in the karst vadose zone (unsaturated zone) more intensively during drier years. Quercus ilex, a species well- adapted to water stress, which grows at the drier site, uses the deep water resource very early in the summer season. Conversely, the two other species exploit the deep water resource only during severe drought. These results open up new perspectives to a better understanding of ecohydrological equilibrium and to improved water balance modeling in karst forest settings.
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Affiliation(s)
- Simon Damien Carrière
- INRA, UMR 1114 EMMAH, Domaine Saint Paul, INRA Centre de recherche PACA, 228 route de l'Aérodrome, CS 40509, Domaine Saint-Paul, Site Agroparc, France.
| | - Nicolas K Martin-StPaul
- INRA, URFM, Domaine Saint Paul, INRA Centre de recherche PACA, 228 route de l'Aérodrome, CS 40509, Domaine Saint-Paul, Site Agroparc, France
| | - Coffi Belmys Cakpo
- INRA, PSH, Domaine Saint Paul, INRA Centre de recherche PACA, 228 route de l'Aérodrome, CS 40509, Domaine Saint-Paul, Site Agroparc, France
| | - Nicolas Patris
- IRD, Hydroscience Montpellier, 300 Avenue du Professeur Emile Jeanbrau, 34090 Montpellier, France
| | - Marina Gillon
- UAPV, UMR 1114 EMMAH, 301 rue Baruch de Spinoza, BP 21239 84911 Avignon Cedex 9, France
| | | | - Claude Doussan
- INRA, UMR 1114 EMMAH, Domaine Saint Paul, INRA Centre de recherche PACA, 228 route de l'Aérodrome, CS 40509, Domaine Saint-Paul, Site Agroparc, France
| | - Albert Olioso
- INRA, UMR 1114 EMMAH, Domaine Saint Paul, INRA Centre de recherche PACA, 228 route de l'Aérodrome, CS 40509, Domaine Saint-Paul, Site Agroparc, France
| | - Milanka Babic
- UAPV, UMR 1114 EMMAH, 301 rue Baruch de Spinoza, BP 21239 84911 Avignon Cedex 9, France
| | - Arnaud Jouineau
- INRA, URFM, Domaine Saint Paul, INRA Centre de recherche PACA, 228 route de l'Aérodrome, CS 40509, Domaine Saint-Paul, Site Agroparc, France
| | - Guillaume Simioni
- INRA, URFM, Domaine Saint Paul, INRA Centre de recherche PACA, 228 route de l'Aérodrome, CS 40509, Domaine Saint-Paul, Site Agroparc, France
| | - Hendrik Davi
- INRA, URFM, Domaine Saint Paul, INRA Centre de recherche PACA, 228 route de l'Aérodrome, CS 40509, Domaine Saint-Paul, Site Agroparc, France
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116
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Jiang P, Wang H, Meinzer FC, Kou L, Dai X, Fu X. Linking reliance on deep soil water to resource economy strategies and abundance among coexisting understorey shrub species in subtropical pine plantations. THE NEW PHYTOLOGIST 2020; 225:222-233. [PMID: 31247133 DOI: 10.1111/nph.16027] [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: 05/09/2019] [Accepted: 06/21/2019] [Indexed: 06/09/2023]
Abstract
Strategies for deep soil water acquisition (WAdeep ) are critical to a species' adaptation to drought. However, it is unknown how WAdeep determines the abundance and resource economy strategies of understorey shrub species. With data from 13 understorey shrub species in subtropical coniferous plantations, we investigated associations between the magnitude of WAdeep , the seasonal plasticity of WAdeep , midday leaf water potential (Ψmd ), species abundance and resource economic traits across organs. Higher capacity for WAdeep was associated with higher intrinsic water use efficiency, but was not necessary for maintaining higher Ψmd in the dry season nor was it an ubiquitous trait possessed by the most common shrub species. Species with higher seasonal plasticity of WAdeep had lower wood density, indicating that fast species had higher plasticity in deep soil resource acquisition. However, the magnitude and plasticity of WAdeep were not related to shallow fine root economy traits, suggesting independent dimensions of soil resource acquisition between deep and shallow soil. Our results provide new insights into the mechanisms through which the magnitude and plasticity of WAdeep interact with shallow soil and aboveground resource acquisition traits to integrate the whole-plant economic spectrum and, thus, community assembly processes.
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Affiliation(s)
- Peipei Jiang
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Huimin Wang
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100190, China
- Zhongke-Ji'an Institute for Eco-Environmental Sciences, Ji'an, 343000, China
| | - Frederick C Meinzer
- USDA Forest Service, Pacific Northwest Research Station, 3200 SW Jefferson Way, Corvallis, OR, 97331, USA
| | - Liang Kou
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100190, China
- Zhongke-Ji'an Institute for Eco-Environmental Sciences, Ji'an, 343000, China
| | - Xiaoqin Dai
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100190, China
- Zhongke-Ji'an Institute for Eco-Environmental Sciences, Ji'an, 343000, China
| | - Xiaoli Fu
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100190, China
- Zhongke-Ji'an Institute for Eco-Environmental Sciences, Ji'an, 343000, China
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117
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Papastefanou P, Zang CS, Pugh TAM, Liu D, Grams TEE, Hickler T, Rammig A. A Dynamic Model for Strategies and Dynamics of Plant Water-Potential Regulation Under Drought Conditions. FRONTIERS IN PLANT SCIENCE 2020; 11:373. [PMID: 32411150 PMCID: PMC7199548 DOI: 10.3389/fpls.2020.00373] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/16/2020] [Indexed: 05/15/2023]
Abstract
Vegetation responds to drought through a complex interplay of plant hydraulic mechanisms, posing challenges for model development and parameterization. We present a mathematical model that describes the dynamics of leaf water-potential over time while considering different strategies by which plant species regulate their water-potentials. The model has two parameters: the parameter λ describing the adjustment of the leaf water potential to changes in soil water potential, and the parameter Δψww describing the typical 'well-watered' leaf water potentials at non-stressed (near-zero) levels of soil water potential. Our model was tested and calibrated on 110 time-series datasets containing the leaf- and soil water potentials of 66 species under drought and non-drought conditions. Our model successfully reproduces the measured leaf water potentials over time based on three different regulation strategies under drought. We found that three parameter sets derived from the measurement data reproduced the dynamics of 53% of an drought dataset, and 52% of a control dataset [root mean square error (RMSE) < 0.5 MPa)]. We conclude that, instead of quantifying water-potential-regulation of different plant species by complex modeling approaches, a small set of parameters may be sufficient to describe the water potential regulation behavior for large-scale modeling. Thus, our approach paves the way for a parsimonious representation of the full spectrum of plant hydraulic responses to drought in dynamic vegetation models.
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Affiliation(s)
- Phillip Papastefanou
- TUM School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany
- *Correspondence: Phillip Papastefanou, ;
| | - Christian S. Zang
- TUM School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany
| | - Thomas A. M. Pugh
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
- Birmingham Institute of Forest Research, University of Birmingham, Birmingham, United Kingdom
| | - Daijun Liu
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
- Birmingham Institute of Forest Research, University of Birmingham, Birmingham, United Kingdom
| | - Thorsten E. E. Grams
- TUM School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany
| | - Thomas Hickler
- Senckenberg Biodiversity and Climate Research Centre, Frankfurt, Germany
- Department of Physical Geography, Goethe University, Frankfurt, Germany
| | - Anja Rammig
- TUM School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany
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118
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Guo JS, Hultine KR, Koch GW, Kropp H, Ogle K. Temporal shifts in iso/anisohydry revealed from daily observations of plant water potential in a dominant desert shrub. THE NEW PHYTOLOGIST 2020; 225:713-726. [PMID: 31519032 DOI: 10.1111/nph.16196] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 09/06/2019] [Indexed: 05/25/2023]
Abstract
Plant species are characterized along a spectrum of isohydry to anisohydry depending on their regulation of water potential (Ψ), but the plasticity of hydraulic strategies is largely unknown. The role of environmental drivers was evaluated in the hydraulic behavior of Larrea tridentata, a drought-tolerant desert shrub that withstands a wide range of environmental conditions. With a 1.5 yr time-series of 2324 in situ measurements of daily predawn and midday Ψ, the temporal variability of hydraulic behavior was explored in relation to soil water supply, atmospheric demand and temperature. Hydraulic behavior in Larrea was highly dynamic, ranging from partial isohydry to extreme anisohydry. Larrea exhibited extreme anisohydry under wet soil conditions corresponding to periods of high productivity, whereas partial isohydry was exhibited after prolonged dry or cold conditions, when productivity was low. Environmental conditions can strongly influence plant hydraulic behavior at relatively fast timescales, which enhances our understanding of plant drought responses. Although species may exhibit a dominant hydraulic behavior, variable environmental conditions can prompt plasticity in Ψ regulation, particularly for species in seasonally dry climates.
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Affiliation(s)
- Jessica S Guo
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Kevin R Hultine
- Department of Research, Conservation, and Collections, Desert Botanical Garden, Phoenix, AZ, 85008, USA
| | - George W Koch
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Heather Kropp
- Department of Geography, Colgate University, Hamilton, NY, 13346, USA
| | - Kiona Ogle
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011, USA
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, 86011, USA
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119
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Sperlich D, Chang CT, Peñuelas J, Sabaté S. Responses of photosynthesis and component processes to drought and temperature stress: are Mediterranean trees fit for climate change? TREE PHYSIOLOGY 2019; 39:1783-1805. [PMID: 31553458 DOI: 10.1093/treephys/tpz089] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 03/19/2019] [Accepted: 08/15/2019] [Indexed: 05/24/2023]
Abstract
Global warming is raising concerns about the acclimatory capacity of trees and forests, especially in Mediterranean-type ecosystems. The sensitivity of photosynthesis to temperature is a key uncertainty for projecting the magnitude of terrestrial feedbacks on future climate change. While boreal, temperate and tropical species have been comparatively well investigated, our study provides the first comprehensive overview of the seasonal acclimatory responses of photosynthesis and its component processes to temperature in four Mediterranean climax species under natural conditions. We quantified seasonal changes in the responses of net photosynthesis (Anet), stomatal conductance (gs), mesophyllic conductance (gm) and electron-transport rate (Jcf), and investigated their sensitivity to drought and temperature stress in sunlit and shaded leaves of four Mediterranean tree species (Quercus ilex L., Pinus halepensis Mill., Arbutus unedo L. and Quercus pubescens Willd.). Sunlit leaves, but not shaded leaves, showed a pronounced seasonality in the temperature responses of Anet, gs, gm and Jcf. All four species and variables showed a remarkably dynamic and consistent acclimation of the thermal optimum (Topt), reaching peaks in summer ~29-32 °C. Changes in the shape of the response curves were, however, highly species-specific. Under severe drought, Topt of all variables were on average 22-29% lower. This was accompanied by narrower response curves above all in P. halepensis, reducing the optimal range for photosynthesis to the cooler morning or evening periods. Wider temperature-response curves and less strict stomatal control under severe drought were accompanied by wilting and drought-induced leaf shedding in Q. ilex and Q. pubescens and by additional branch dieback in A. unedo. Mild winter conditions led to a high Topt (~19.1-22.2 °C), benefitting the evergreen species, especially P. halepensis. Seasonal acclimation of Anet was explained better by gs and gm being less pronounced in Jcf. Drought was thus a key factor, in addition to growth temperature, to explain seasonal acclimation of photosynthesis. Severe drought periods may exceed more frequently the high acclimatory capacity of Mediterranean trees to high ambient temperatures, which could lead to reduced growth, increased leaf shedding and, for some species such as A. unedo, increased mortality risk.
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Affiliation(s)
- D Sperlich
- Chair of Forestry Economics and Forest Planning, Faculty of Environment and Natural Resources, University of Freiburg, 79085 Freiburg im Breisgau, Tennenbacherstr. 4, Germany
| | - C T Chang
- Department of Evolutionary Biology, Ecology and Environmental Sciences (BEECA), University of Barcelona (UB), Av. Diagonal 643, 08028 Barcelona
- CREAF, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain
| | - J Peñuelas
- CREAF, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain
- Global Ecology Unit CREAF-CSIC-UAB, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain
| | - S Sabaté
- Department of Evolutionary Biology, Ecology and Environmental Sciences (BEECA), University of Barcelona (UB), Av. Diagonal 643, 08028 Barcelona
- CREAF, Cerdanyola del Vallès, 08193 Barcelona, Catalonia, Spain
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120
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Tomasella M, Casolo V, Aichner N, Petruzzellis F, Savi T, Trifilò P, Nardini A. Non-structural carbohydrate and hydraulic dynamics during drought and recovery in Fraxinus ornus and Ostrya carpinifolia saplings. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2019; 145:1-9. [PMID: 31665662 DOI: 10.1016/j.plaphy.2019.10.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/14/2019] [Accepted: 10/17/2019] [Indexed: 06/10/2023]
Abstract
The maintenance of hydraulic function during and after a drought event is crucial for tree survival, but the importance of non-structural carbohydrates (NSCs) in the recovery phase is still debated. We tested whether higher NSC availability facilitates post-drought hydraulic recovery, by applying a short-term drought (Sdr) and a long-term drought combined with shading (Ldr+sh) in Fraxinus ornus and Ostrya carpinifolia. Plants were then re-irrigated and recovery was checked 24 h later, by measuring water potential, stem percentage loss of hydraulic conductance (PLC) and NSC content. The relative magnitude of hydraulic and carbon constraints was also assessed in desiccated plants. During drought, PLC increased only in F. ornus, while it was maintained almost constant in O. carpinifolia due to tighter stomatal control of xylem pressure (i.e. more isohydric). In F. ornus, only Sdr plants maintained high NSC contents at the end of drought and, when re-irrigated, recovered PLC to control values. Whereas hydraulic failure was ubiquitous, only F. ornus depleted NSC reserves at mortality. Our results suggest that preserving higher NSC content at the end of a drought can be important for the hydraulic resilience of trees.
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Affiliation(s)
- Martina Tomasella
- Dipartimento di Scienze della Vita, Università di Trieste. Via L. Giorgieri 10, 34127, Trieste, Italy
| | - Valentino Casolo
- Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Università di Udine. Via delle Scienze 91, 33100, Udine, Italy
| | - Natalie Aichner
- Dipartimento di Scienze della Vita, Università di Trieste. Via L. Giorgieri 10, 34127, Trieste, Italy
| | - Francesco Petruzzellis
- Dipartimento di Scienze della Vita, Università di Trieste. Via L. Giorgieri 10, 34127, Trieste, Italy
| | - Tadeja Savi
- Institute of Botany, Department of Integrative Biology and Biodiversity Research, BOKU, Gregor-Mendel-Straße 33, Vienna, 1190, Austria
| | - Patrizia Trifilò
- Dipartimento di Scienze Chimiche, Biologiche, Farmaceutiche ed Ambientali, Università di Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166, Messina, Italy
| | - Andrea Nardini
- Dipartimento di Scienze della Vita, Università di Trieste. Via L. Giorgieri 10, 34127, Trieste, Italy.
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121
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Wang X, Qiu B, Li W, Zhang Q. Impacts of drought and heatwave on the terrestrial ecosystem in China as revealed by satellite solar-induced chlorophyll fluorescence. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 693:133627. [PMID: 31377349 DOI: 10.1016/j.scitotenv.2019.133627] [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: 05/09/2019] [Revised: 07/23/2019] [Accepted: 07/26/2019] [Indexed: 06/10/2023]
Abstract
Droughts and heatwaves have been and will continue to bring large risks to terrestrial ecosystems. However, the understanding of how plants respond to drought and heatwave over broad spatial scales is still limited. In this paper, we use the 2009/2010 drought in Yunnan and the 2013 heatwave over southern China as case studies to investigate the potential of using satellite-observed solar-induced chlorophyll fluorescence (SIF) to monitor vegetation responses to drought and heatwave over broad spatial scales. The 2009/2010 drought onset follows a strong soil moisture deficit due to the yearlong below-normal precipitation in Yunnan from the autumn of 2009 to the spring of 2010. In the summer of 2013, southern China experienced the strongest heatwave due to the sudden temperature increase and rainfall deficit. The results show that SIF can reasonably capture the spatial and temporal dynamics of drought and heatwave development, as indicated by the large reduction in fluorescence yield (SIFyield). Moreover, SIFyield demonstrates a significant reduction and earlier response than traditional vegetation indices (enhanced vegetation index, EVI) during the early stages of drought and heatwave events. For both study areas, the spatial and temporal correlation analysis demonstrates that the SIFyield anomalies are more sensitive to a high vapor pressure deficit (VPD) than low soil moisture. This study implies that satellite observations of SIF have great potential for accurate and timely monitoring of drought and heatwave developments.
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Affiliation(s)
- Xiaorong Wang
- Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, International Institute for Earth System Sciences, Nanjing University, Nanjing, China; Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, China
| | - Bo Qiu
- Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, International Institute for Earth System Sciences, Nanjing University, Nanjing, China; Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, China.
| | - Wenkai Li
- Key Laboratory of Meteorological Disaster, Ministry of Education (KLME)/Joint International Research Laboratory of Climate and Environment Change (ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), Nanjing University of Information Science & Technology, Nanjing, China
| | - Qian Zhang
- Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, International Institute for Earth System Sciences, Nanjing University, Nanjing, China; Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, China
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122
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Holanda AER, Souza BC, Carvalho ECD, Oliveira RS, Martins FR, Muniz CR, Costa RC, Soares AA. How do leaf wetting events affect gas exchange and leaf lifespan of plants from seasonally dry tropical vegetation? PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:1097-1109. [PMID: 31251437 DOI: 10.1111/plb.13023] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 06/25/2019] [Indexed: 06/09/2023]
Abstract
Foliar uptake of dew is likely an important mechanism of water acquisition for plants from tropical dry environments. However, there is still limited experimental evidence describing the anatomical pathways involved in this process and the effects of this water subsidy on the maintenance of gas exchange and leaf lifespan of species from seasonally dry tropical vegetation such as the Brazilian caatinga. We performed scanning electron, bright-field and confocal microscopic analyses and used apoplastic tracers to examine the foliar water uptake (FWU) routes in four woody species with different foliar phenology and widely distributed in the caatinga. Leaves of plants subjected to water stress were exposed to dew simulation to evaluate the effects of the FWU on leaf water potentials, gas exchange and leaf lifespan. All species absorbed water through their leaf cuticles and/or peltate trichomes but FWU capacity differed among species. Leaf wetting by dew increased leaf lifespan duration up to 36 days compared to plants in the drought treatment. A positive effect on leaf gas exchange and new leaf production was only observed in the anisohydric and evergreen species. We showed that leaf wetting by dew is relevant for the physiology and leaf lifespan of plants from seasonally dry tropical vegetation, especially for evergreen species.
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Affiliation(s)
- A E R Holanda
- Graduate Program in Ecology and Natural Resources, Department of Biology, Federal University of Ceará, Fortaleza, Brazil
| | - B C Souza
- Graduate Program in Ecology and Natural Resources, Department of Biology, Federal University of Ceará, Fortaleza, Brazil
| | - E C D Carvalho
- Graduate Program in Ecology and Natural Resources, Department of Biology, Federal University of Ceará, Fortaleza, Brazil
| | - R S Oliveira
- Department of Plant Biology, Institute of Biology, University of Campinas - UNICAMP, Campinas, Brazil
| | - F R Martins
- Department of Plant Biology, Institute of Biology, University of Campinas - UNICAMP, Campinas, Brazil
| | - C R Muniz
- Embrapa Tropical Agroindustry, Fortaleza, Brazil
| | - R C Costa
- Department of Biology, Federal University of Ceará, Fortaleza, Brazil
| | - A A Soares
- Department of Biology, Federal University of Ceará, Fortaleza, Brazil
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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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124
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McCulloh KA, Domec JC, Johnson DM, Smith DD, Meinzer FC. A dynamic yet vulnerable pipeline: Integration and coordination of hydraulic traits across whole plants. PLANT, CELL & ENVIRONMENT 2019; 42:2789-2807. [PMID: 31273812 DOI: 10.1111/pce.13607] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 07/01/2019] [Accepted: 07/02/2019] [Indexed: 06/09/2023]
Abstract
The vast majority of measurements in the field of plant hydraulics have been on small-diameter branches from woody species. These measurements have provided considerable insight into plant functioning, but our understanding of plant physiology and ecology would benefit from a broader view, because branch hydraulic properties are influenced by many factors. Here, we discuss the influence that other components of the hydraulic network have on branch vulnerability to embolism propagation. We also modelled the impact of changes in the ratio of root-to-leaf areas and soil texture on vulnerability to hydraulic failure along the soil-to-leaf continuum and showed that hydraulic function is better maintained through changes in root vulnerability and root-to-leaf area ratio than in branch vulnerability. Differences among species in the stringency with which they regulate leaf water potential and in reliance on stored water to buffer changes in water potential also affect the need to construct embolism resistant branches. Many approaches, such as measurements on fine roots, small individuals, combining sap flow and psychrometry techniques, and modelling efforts, could vastly improve our understanding of whole-plant hydraulic functioning. A better understanding of how traits are coordinated across the whole plant will improve predictions for plant function under future climate conditions.
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Affiliation(s)
| | - Jean-Christophe Domec
- Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA
- Bordeaux Sciences Agro, UMR 1391 INRA-ISPA, 33175, Gradignan Cedex, France
| | - Daniel M Johnson
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA
| | - Duncan D Smith
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Frederick C Meinzer
- USDA Forest Service, Pacific Northwest Research Station, Corvallis, OR, 97331, USA
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125
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Norway Spruce (Picea abies L.) Provenances Use Different Physiological Strategies to Cope with Water Deficit. FORESTS 2019. [DOI: 10.3390/f10080651] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Research Highlights: In this study, we found different regulatory mechanisms in two contrasting provenances of Norway spruce responding to progressive drought stress. Background and Objectives: In the context of climate and environmental changes, the following question of high importance in scientific studies is: How will Norway spruce, which forms a dominant component in European mountain and boreal forests, be able to cope with the increasing frequencies and intensities of drought periods? The aim of the study was to investigate the physiological responses of eight-month-old seedlings, as a most vulnerable phase of forest tree life, for different spruce provenances, to find out variable strategies in relation to controlled drought stress. Materials and Methods: We performed an experiment under controlled conditions with spruce seedlings from a climatologically warmer stand of 410 m above sea level (a.s.l.), and a moderately cool stand of 931 m a.s.l. The soil water content, leaf predawn water potential, the osmotic potential of needles, the relative water content of needles, and the photosynthetic performance and the contents of primary metabolites (proline and abscisic acid) were investigated as indicators of the spruce seedlings’ responses to water stress. The status of the indicators was analyzed at different temporal intervals, using repeated measures analysis of variance (ANOVA), reflecting the seedlings´ water conditions (early drought, drought, or recovery). On a daily basis, the differences among the indicators were tested with one-way ANOVA. A principal component analysis (PCA) was used to identify the provenance-specific responses of tree drought indicators in a multi-dimensional data set. Results: The responses to drought stress differed between the provenances. Whereas seedlings of ´warm´ provenance from a low altitude performed a conservation strategy, with high amounts of accumulated abscisic acid and closing the stomata faster, the reactions of ´cool´ provenance seedlings from a higher altitude were not so sensitive and the plants’ water supply and photosynthetic performance remained significantly higher. These findings indicate that a higher drought resistance in ´cool´ provenance could be related to greater amounts of proline amino-acids, which are accumulated from the beginning of the drought simulation. Furthermore, proline accumulation resulting in increased stress tolerance is controlled through another mechanism than osmotic adjustment. Conclusions: The observed variations in the regulatory mechanisms used to develop adaptive strategies in different provenances are an important factor for seedling survival under a changing climate.
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126
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Condo TK, Reinhardt K. Large variation in branch and branch-tip hydraulic functional traits in Douglas-fir (Pseudotsuga menziesii) approaching lower treeline. TREE PHYSIOLOGY 2019; 39:1461-1472. [PMID: 31135912 DOI: 10.1093/treephys/tpz058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/29/2019] [Accepted: 05/13/2019] [Indexed: 06/09/2023]
Abstract
Few studies have quantified intraspecific variation of hydraulic functional traits in conifers across elevation gradients that include range boundaries. In the Intermountain West, USA, the lower elevational limit of forests (lower treeline) is generally assumed to be caused by water limitations to growth and water relations, yet few studies directly show this. To test this assumption, we measured changes in a suite of traits that characterize drought tolerance such as drought-induced hydraulic vulnerability, hydraulic transport capacity and morphological traits in branch tips and branches of Douglas-fir (Pseudotsuga menziesii var. glauca (Mirb.) Franco) along a 400-m elevation gradient in southeastern Idaho that included lower treeline. As elevation decreased, vulnerability to hydraulic dysfunction and maximum conductivity both decreased in branches; some hydraulic safety-efficiency trade-offs were evident. In branch tips, the water potential at the turgor loss point decreased, while maximum conductance increased with decreasing elevation, highlighting that branch-tip-level responses to less moisture availability accompanied by warmer temperatures might not be coordinated with branch responses. As the range boundary was approached, we did not observe non-linear changes in parameters among sites or increased variance within sites, which current ecological hypotheses on range limits suggest. Our results indicate that there is substantial plasticity in hydraulic functional traits in branch tips and branches of Douglas-fir, although the direction of the trends along the elevation gradient sometimes differed between organs. Such plasticity may mitigate the negative impacts of future drought on Douglas-fir productivity, slowing shifts in its range that are expected to occur with climate change.
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Affiliation(s)
- Theresa K Condo
- Department of Biological Sciences, Idaho State University, 921 S 8th Ave., Stop 8007, Pocatello, ID 83209, USA
| | - Keith Reinhardt
- Department of Biological Sciences, Idaho State University, 921 S 8th Ave., Stop 8007, Pocatello, ID 83209, USA
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127
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Gao J, Tian K. Stem and leaf traits as co-determinants of canopy water flux. PLANT DIVERSITY 2019; 41:258-265. [PMID: 31528785 PMCID: PMC6743011 DOI: 10.1016/j.pld.2019.06.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/10/2019] [Accepted: 06/12/2019] [Indexed: 05/26/2023]
Abstract
Transpiration through stomata in tree canopies plays an important role in terrestrial water cycles. However, the empirical relationship between leaf stomata anatomy and canopy stomatal conductance (G s) is surprisingly rare, thereby the underlying biological mechanisms of terrestrial water flux are not well elucidated. To gain further insight into these mechanisms, we reanalyzed the dataset of G s previously reported by Gao et al. (2015) using a quantile regression model. The results indicated that the reference G s (G sref, G s at 1 kPa) was negatively correlated with wood density at each quantile, which confirmed previous data; however, G sref was significantly correlated with stomatal density at the 0.6 quantile, i.e., 450 stomata mm-2. This highlighted the potential of using stomatal density as a trait to predict canopy water flux. A conceptual model of co-determinants of xylem and stomatal morphology suggests that these traits and their coordination may play a critical role in determining tree growth, physiological homeostatic response to environmental variables, water use efficiency, and drought resistance.
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Affiliation(s)
- Jianguo Gao
- Department of Ecology, College of Urban and Environmental Sciences, Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, No.5 Yiheyuan Road Haidian District, Beijing, 100871, PR China
- Coastal Ecosystems Research Station of the Yangtze River Estuary, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Fudan University, Shanghai, 200438, PR China
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, Chinese Academy of Sciences, South China Botanical Garden, Guangzhou, 510650, PR China
| | - Kai Tian
- School of Life Sciences, Nanjing University, Nanjing, 210023, PR China
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128
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Lachenbruch B, Zhao JP. Effects of phloem on canopy dieback, tested with manipulations and a canker pathogen in the Corylus avellana/Anisogramma anomala host/pathogen system. TREE PHYSIOLOGY 2019; 39:1086-1098. [PMID: 30938425 DOI: 10.1093/treephys/tpz027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 02/18/2019] [Accepted: 03/03/2019] [Indexed: 06/09/2023]
Abstract
Canker pathogens cause necrosis of the phloem, but in many host/pathogen systems, they also cause canopy dieback, which implicates xylem, not phloem dysfunction. We hypothesize that this dieback distal to the canker is caused by water stress resulting from the lack of a phloem-to-xylem connection, which in a healthy plant would allow delivery of nonstructural carbohydrates (NSCs) and water inward to aid in xylem embolism refilling. We tested several components of this hypothesis in the host/pathogen system Corylus avellana L./Anisogramma anomala (Peck) E. Müll (Eastern filbert blight). Cankers were non-girdling and usually ≥0.1 m long. As expected, healthy controls had higher specific conductivity (Ks) than diseased stems, but unexpectedly, had similar moisture content (m.c.), showing that the lower Ks did not result from more embolisms in the diseased stems. Moreover, manipulations that removed cambium and phloem to simulate a canker, or that shaded stems to lower NSCs, did not result in lower Ks or m.c. than controls. The outer millimeter of xylem adjacent to a canker had infrequent tyloses and/or fungal hyphae in many but not all samples, and dye studies showed little xylem water transport in that region, but the incidence of these blockages was insufficient to cause the observed 19% decrease in Ks. Healthy stems had higher m.c. than diseased stems above the canker (or analogous) location and were longer for the same leaf weight, suggestive of water stress in the upper portion of diseased stems. These results suggest that dieback distal to cankers in this system results from the bottleneck in water transport in the region adjacent to a canker, but did not find evidence to support the requirement of a phloem-to-xylem connection for continued water transport.
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Affiliation(s)
- B Lachenbruch
- Department of Forest Ecosystems & Society, Oregon State University, OR
| | - Jia-Ping Zhao
- State Key Laboratory of Tree Genetics and Breeding, Forestry Institute of New Technology, Chinese Academy of Forestry, Beijing, China
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129
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Martinez-Vilalta J, Anderegg WRL, Sapes G, Sala A. Greater focus on water pools may improve our ability to understand and anticipate drought-induced mortality in plants. THE NEW PHYTOLOGIST 2019; 223:22-32. [PMID: 30560995 DOI: 10.1111/nph.15644] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 12/06/2018] [Indexed: 05/23/2023]
Abstract
Drought-induced tree mortality has major impacts on ecosystem carbon and water cycles, and is expected to increase in forests across the globe with climate change. A large body of research in the past decade has advanced our understanding of plant water and carbon relations under drought. However, despite intense research, we still lack generalizable, cross-scale indicators of mortality risk. In this Viewpoint, we propose that a more explicit consideration of water pools could improve our ability to monitor and anticipate mortality risk. Specifically, we focus on the relative water content (RWC), a classic metric in plant water relations, as a potential indicator of mortality risk that is physiologically relevant and integrates different aspects related to hydraulics, stomatal responses and carbon economy under drought. Measures of plant water content are likely to have a strong mechanistic link with mortality and to be integrative, threshold-prone and relatively easy to measure and monitor at large spatial scales, and may complement current mortality metrics based on water potential, loss of hydraulic conductivity and nonstructural carbohydrates. We discuss some of the potential advantages and limitations of these metrics to improve our capacity to monitor and predict drought-induced tree mortality.
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Affiliation(s)
- Jordi Martinez-Vilalta
- CREAF, Cerdanyola del Valles, 08193, Barcelona, Spain
- Universitat Autònoma de Barcelona, Cerdanyola del Valles, 08193, Barcelona, Spain
| | | | - Gerard Sapes
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Anna Sala
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
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130
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Fu X, Meinzer FC, Woodruff DR, Liu YY, Smith DD, McCulloh KA, Howard AR. Coordination and trade-offs between leaf and stem hydraulic traits and stomatal regulation along a spectrum of isohydry to anisohydry. PLANT, CELL & ENVIRONMENT 2019; 42:2245-2258. [PMID: 30820970 DOI: 10.1111/pce.13543] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 02/22/2019] [Accepted: 02/24/2019] [Indexed: 06/09/2023]
Abstract
The degree of plant iso/anisohydry, a widely used framework for classifying species-specific hydraulic strategies, integrates multiple components of the whole-plant hydraulic pathway. However, little is known about how it associates with coordination of functional and structural traits within and across different organs. We examined stem and leaf hydraulic capacitance and conductivity/conductance, stem xylem anatomical features, stomatal regulation of daily minimum leaf and stem water potential (Ψ), and the kinetics of stomatal responses to vapour pressure deficit (VPD) in six diverse woody species differing markedly in their degree of iso/anisohydry. At the stem level, more anisohydric species had higher wood density and lower native capacitance and conductivity. Like stems, leaves of more anisohydric species had lower hydraulic conductance; however, unlike stems, their leaves had higher native capacitance at their daily minimum values of leaf Ψ. Moreover, rates of VPD-induced stomatal closure were related to intrinsic rather than native leaf capacitance and were not associated with species' degree of iso/anisohydry. Our results suggest a trade-off between hydraulic storage and efficiency in the leaf, but a coordination between hydraulic storage and efficiency in the stem along a spectrum of plant iso/anisohydry.
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Affiliation(s)
- Xiaoli Fu
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
- Zhongke-Ji'an Institute for Eco-Environmental Sciences, Ji'an, China
| | | | - David R Woodruff
- USDA Forest Service, Pacific Northwest Research Station, Corvallis, Oregon
| | - Yan-Yan Liu
- Key Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Guangxi Teachers Education University, Nanning, China
| | - Duncan D Smith
- Department of Botany, University of Wisconsin, Madison, Wisconsin
| | | | - Ava R Howard
- Department of Biology, Western Oregon University, Monmouth, Oregon
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131
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Beverly DP, Guadagno CR, Bretfeld M, Speckman HN, Albeke SE, Ewers BE. Hydraulic and photosynthetic responses of big sagebrush to the 2017 total solar eclipse. Sci Rep 2019; 9:8839. [PMID: 31222163 PMCID: PMC6586607 DOI: 10.1038/s41598-019-45400-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 06/04/2019] [Indexed: 11/09/2022] Open
Abstract
The total solar eclipse of August 21, 2017 created a path of totality ~115 km in width across the United States. While eclipse observations have shown distinct responses in animal behavior often emulating nocturnal behavior, the influence of eclipses on plant physiology are less understood. We investigated physiological perturbations due to rapid changes of sunlight and air temperature in big sagebrush (Artemisia tridentata ssp. vaseyana), a desert shrub common within the path of eclipse totality. Leaf gas exchange, water potential, and chlorophyll a fluorescence were monitored during the eclipse and compared to responses obtained the day before in absence of the eclipse. On the day of the eclipse, air temperature decreased by 6.4 °C, coupled with a 1.0 kPa drop in vapor pressure deficit having a 9-minute lag following totality. Using chlorophyll a fluorescence measurements, we found photosynthetic efficiency of photosystem II (Fv'/Fm') recovered to near dark acclimated state (i.e., 87%), but the short duration of darkness did not allow for complete recovery. Gas exchange data and a simple light response model were used to estimate a 14% reduction in carbon assimilation for one day over sagebrush dominated areas within the path of totality for the Western United States.
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Affiliation(s)
- Daniel P Beverly
- Department of Botany, University of Wyoming, Laramie, WY, 82071, USA.
- Water Resources, Environmental Science and Engineering, University of Wyoming, Laramie, WY, 82071, USA.
| | | | - Mario Bretfeld
- Department of Botany, University of Wyoming, Laramie, WY, 82071, USA
| | - Heather N Speckman
- Department of Botany, University of Wyoming, Laramie, WY, 82071, USA
- Program in Ecology, University of Wyoming, Laramie, WY, 82071, USA
| | - Shannon E Albeke
- Department of Geography and Wyoming Geographic Information Service Center, University of Wyoming, Laramie, WY, 82071, USA
- Program in Ecology, University of Wyoming, Laramie, WY, 82071, USA
| | - Brent E Ewers
- Department of Botany, University of Wyoming, Laramie, WY, 82071, USA
- Program in Ecology, University of Wyoming, Laramie, WY, 82071, USA
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132
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Kannenberg SA, Novick KA, Phillips RP. Anisohydric behavior linked to persistent hydraulic damage and delayed drought recovery across seven North American tree species. THE NEW PHYTOLOGIST 2019; 222:1862-1872. [PMID: 30664253 DOI: 10.1111/nph.15699] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 01/15/2019] [Indexed: 05/08/2023]
Abstract
The isohydry-anisohydry spectrum has become a popular way to characterize plant drought responses and recovery processes. Despite the proven utility of this framework for understanding the interconnected physiological changes plants undergo in response to water stress, new challenges have arisen pertaining to the traits and tradeoffs that underlie this concept. To test the utility of this framework for understanding hydraulic traits, drought physiology and recovery, we applied a 6 wk experimental soil moisture reduction to seven tree species followed by a 6 wk recovery period. Throughout, we measured hydraulic traits and monitored changes in gas exchange, leaf water potential, and hydraulic conductivity. Species' hydraulic traits were not coordinated, as some anisohydric species had surprisingly low resistance to embolism (P50 ) and negative safety margins. In addition to widespread hydraulic damage, these species also experienced reductions in photosynthesis and stem water potential during water stress, and delayed recovery time. Given that we observed no benefit of being anisohydric either during or after drought, our results indicate the need to reconsider the traits and tradeoffs that underlie anisohydric behavior, and to consider the environmental, biological and edaphic processes that could allow this strategy to flourish in forests.
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Affiliation(s)
- Steven A Kannenberg
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
| | - Kimberly A Novick
- School of Public and Environmental Affairs, Indiana University, Bloomington, IN, 47405, USA
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133
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Novick KA, Konings AG, Gentine P. Beyond soil water potential: An expanded view on isohydricity including land-atmosphere interactions and phenology. PLANT, CELL & ENVIRONMENT 2019; 42:1802-1815. [PMID: 30632172 DOI: 10.1111/pce.13517] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 01/02/2019] [Accepted: 01/07/2019] [Indexed: 05/21/2023]
Abstract
Over the past decade, the concept of isohydry or anisohydry, which describes the link between soil water potential (ΨS ), leaf water potential (ΨL ), and stomatal conductance (gs ), has soared in popularity. However, its utility has recently been questioned, and a surprising lack of coordination between the dynamics of ΨL and gs across biomes has been reported. Here, we offer a more expanded view of the isohydricity concept that considers effects of vapour pressure deficit (VPD) and leaf area index (AL ) on the apparent sensitivities of ΨL and gs to drought. After validating the model with tree- and ecosystem-scale data, we find that within a site, isohydricity is a strong predictor of limitations to stomatal function, though variation in VPD and leaf area, among other factors, can challenge its diagnosis. Across sites, the theory predicts that the degree of isohydricity is a good predictor of the sensitivity of gs to declining soil water in the absence of confounding effects from other drivers. However, if VPD effects are significant, they alone are sufficient to decouple the dynamics of ΨL and gs entirely. We conclude with a set of practical recommendations for future applications of the isohydricity framework within and across sites.
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Affiliation(s)
- Kimberly A Novick
- School of Public and Environmental Affairs, Indiana University Bloomington, Bloomington, Indiana
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, Stanford, California
| | - Pierre Gentine
- Department of Earth and Environmental Engineering, Columbia University, New York, New York
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134
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Wei L, Xu C, Jansen S, Zhou H, Christoffersen BO, Pockman WT, Middleton RS, Marshall JD, McDowell NG. A heuristic classification of woody plants based on contrasting shade and drought strategies. TREE PHYSIOLOGY 2019; 39:767-781. [PMID: 30715506 DOI: 10.1093/treephys/tpy146] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 11/21/2018] [Accepted: 12/19/2018] [Indexed: 06/09/2023]
Abstract
Woody plants vary in their adaptations to drought and shade. For a better prediction of vegetation responses to drought and shade within dynamic global vegetation models, it is critical to group species into functional types with similar adaptations. One of the key challenges is that the adaptations are generally determined by a large number of plant traits that may not be available for a large number of species. In this study, we present two heuristic woody plant groups that were separated using cluster analysis in a three-dimensional trait-environment space based on three key metrics for each species: mean xylem embolism resistance, shade tolerance and habitat aridity. The two heuristic groups separate these species into tolerators and avoiders. The tolerators either rely on their high embolism resistance to tolerate drought in arid habitats (e.g., Juniperus and Prunus) or rely on high shade tolerance to withstand shaded conditions in wet habitats (e.g., Picea, Abies and Acer). In contrast, all avoiders have low embolism resistance and low shade tolerance. In arid habitats, avoiders tend to minimize catastrophic embolism (e.g., most Pinus species) while in wet habitats, they may survive despite low shade tolerance (e.g., Betula, Populus, Alnus and Salix). Because our approach links traits to the environmental conditions, we expect it could be a promising framework for predicting changes in species composition, and therefore ecosystem function, under changing environmental conditions.
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Affiliation(s)
- Liang Wei
- Los Alamos National Laboratory, Earth and Environmental Sciences, Los Alamos, NM, USA
| | - Chonggang Xu
- Los Alamos National Laboratory, Earth and Environmental Sciences, Los Alamos, NM, USA
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, Ulm, Germany
| | - Hang Zhou
- Descartes Labs, Inc., 1613 Paseo De Peralta Ste. 200, Santa Fe, NM, USA
- Department of Geography, University of Idaho, Moscow, ID, USA
| | - Bradley O Christoffersen
- Department of Biology and School of Earth, Environmental, and Marine Sciences, University of Texas Rio Grande Valley, Edinburg, TX, USA
| | - William T Pockman
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Richard S Middleton
- Los Alamos National Laboratory, Earth and Environmental Sciences, Los Alamos, NM, USA
| | - John D Marshall
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogmarksgränd, Umeå, Sweden
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135
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Dickman LT, McDowell NG, Grossiord C, Collins AD, Wolfe BT, Detto M, Wright SJ, Medina-Vega JA, Goodsman D, Rogers A, Serbin SP, Wu J, Ely KS, Michaletz ST, Xu C, Kueppers L, Chambers JQ. Homoeostatic maintenance of nonstructural carbohydrates during the 2015-2016 El Niño drought across a tropical forest precipitation gradient. PLANT, CELL & ENVIRONMENT 2019; 42:1705-1714. [PMID: 30537216 DOI: 10.1111/pce.13501] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 11/26/2018] [Accepted: 12/02/2018] [Indexed: 06/09/2023]
Abstract
Nonstructural carbohydrates (NSCs) are essential for maintenance of plant metabolism and may be sensitive to short- and long-term climatic variation. NSC variation in moist tropical forests has rarely been studied, so regulation of NSCs in these systems is poorly understood. We measured foliar and branch NSC content in 23 tree species at three sites located across a large precipitation gradient in Panama during the 2015-2016 El Niño to examine how short- and long-term climatic variation impact carbohydrate dynamics. There was no significant difference in total NSCs as the drought progressed (leaf P = 0.32, branch P = 0.30) nor across the rainfall gradient (leaf P = 0.91, branch P = 0.96). Foliar soluble sugars decreased while starch increased over the duration of the dry period, suggesting greater partitioning of NSCs to storage than metabolism or transport as drought progressed. There was a large variation across species at all sites, but total foliar NSCs were positively correlated with leaf mass per area, whereas branch sugars were positively related to leaf temperature and negatively correlated with daily photosynthesis and wood density. The NSC homoeostasis across a wide range of conditions suggests that NSCs are an allocation priority in moist tropical forests.
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Affiliation(s)
- Lee Turin Dickman
- Earth & Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Nate G McDowell
- Earth Systems Analysis & Modeling, Pacific Northwest National Laboratory, Richland, Washington
| | - Charlotte Grossiord
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Forest Dynamics Research Unit, Birmensdorf, Switzerland
| | - Adam D Collins
- Earth & Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Brett T Wolfe
- Smithsonian Tropical Research Institute, Balboa, Panama
| | - Matteo Detto
- Ecology and Evolutionary Biology Department, Princeton University, Princeton, New Jersey
| | | | - José A Medina-Vega
- Smithsonian Tropical Research Institute, Balboa, Panama
- Forest Ecology and Forest Management Group, Wageningen University and Research, Wageningen, The Netherlands
| | - Devin Goodsman
- Earth & Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Alistair Rogers
- Environmental & Climate Sciences Department, Brookhaven National Laboratory, New York, New York
| | - Shawn P Serbin
- Environmental & Climate Sciences Department, Brookhaven National Laboratory, New York, New York
| | - Jin Wu
- Environmental & Climate Sciences Department, Brookhaven National Laboratory, New York, New York
| | - Kim S Ely
- Environmental & Climate Sciences Department, Brookhaven National Laboratory, New York, New York
| | - Sean T Michaletz
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Chonggang Xu
- Earth & Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico
| | - Lara Kueppers
- Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, California
| | - Jeffrey Q Chambers
- Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, California
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136
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Li X, Blackman CJ, Peters JMR, Choat B, Rymer PD, Medlyn BE, Tissue DT. More than iso/anisohydry: Hydroscapes integrate plant water use and drought tolerance traits in 10 eucalypt species from contrasting climates. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13320] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Ximeng Li
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
| | - Chris J. Blackman
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
| | - Jennifer M. R. Peters
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
| | - Paul D. Rymer
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
| | - Belinda E. Medlyn
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
| | - David T. Tissue
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
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137
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Feng X, Ackerly DD, Dawson TE, Manzoni S, McLaughlin B, Skelton RP, Vico G, Weitz AP, Thompson SE. Beyond isohydricity: The role of environmental variability in determining plant drought responses. PLANT, CELL & ENVIRONMENT 2019; 42:1104-1111. [PMID: 30513545 DOI: 10.1111/pce.13486] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 11/04/2018] [Accepted: 11/20/2018] [Indexed: 05/21/2023]
Abstract
Despite the appeal of the iso/anisohydric framework for classifying plant drought responses, recent studies have shown that such classifications can be strongly affected by a plant's environment. Here, we present measured in situ drought responses to demonstrate that apparent isohydricity can be conflated with environmental conditions that vary over space and time. In particular, we (a) use data from an oak species (Quercus douglasii) during the 2012-2015 extreme drought in California to demonstrate how temporal and spatial variability in the environment can influence plant water potential dynamics, masking the role of traits; (b) explain how these environmental variations might arise from climatic, topographic, and edaphic variability; (c) illustrate, through a "common garden" thought experiment, how existing trait-based or response-based isohydricity metrics can be confounded by these environmental variations, leading to Type-1 (false positive) and Type-2 (false negative) errors; and (d) advocate for the use of model-based approaches for formulating alternate classification schemes. Building on recent insights from greenhouse and vineyard studies, we offer additional evidence across multiple field sites to demonstrate the importance of spatial and temporal drivers of plants' apparent isohydricity. This evidence challenges the use of isohydricity indices, per se, to characterize plant water relations at the global scale.
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Affiliation(s)
- Xue Feng
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Minneapolis, Minnesota, 55455, USA
| | - David D Ackerly
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California, 94720, USA
| | - Todd E Dawson
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California, 94720, USA
- Department of Environmental Sciences, Policy, and Management, University of California, Berkeley, Berkeley, California, 94720, USA
| | - Stefano Manzoni
- Department of Physical Geography, Stockholm University, Stockholm, Sweden
- Bolin Centre for Climate Research, Stockholm, Sweden
| | | | - Robert P Skelton
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California, 94720, USA
| | - Giulia Vico
- Department of Crop Production Ecology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden
| | - Andrew P Weitz
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California, 94720, USA
| | - Sally E Thompson
- Department of Civil and Environmental Engineering, University of California, Berkeley, Berkeley, California, 94720, USA
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138
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Qaderi MM, Martel AB, Dixon SL. Environmental Factors Influence Plant Vascular System and Water Regulation. PLANTS 2019; 8:plants8030065. [PMID: 30875945 PMCID: PMC6473727 DOI: 10.3390/plants8030065] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/28/2019] [Accepted: 03/11/2019] [Indexed: 11/16/2022]
Abstract
Developmental initiation of plant vascular tissue, including xylem and phloem, from the vascular cambium depends on environmental factors, such as temperature and precipitation. Proper formation of vascular tissue is critical for the transpiration stream, along with photosynthesis as a whole. While effects of individual environmental factors on the transpiration stream are well studied, interactive effects of multiple stress factors are underrepresented. As expected, climate change will result in plants experiencing multiple co-occurring environmental stress factors, which require further studies. Also, the effects of the main climate change components (carbon dioxide, temperature, and drought) on vascular cambium are not well understood. This review aims at synthesizing current knowledge regarding the effects of the main climate change components on the initiation and differentiation of vascular cambium, the transpiration stream, and photosynthesis. We predict that combined environmental factors will result in increased diameter and density of xylem vessels or tracheids in the absence of water stress. However, drought may decrease the density of xylem vessels or tracheids. All interactive combinations are expected to increase vascular cell wall thickness, and therefore increase carbon allocation to these tissues. A comprehensive study of the effects of multiple environmental factors on plant vascular tissue and water regulation should help us understand plant responses to climate change.
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Affiliation(s)
- Mirwais M Qaderi
- Department of Biology, Mount Saint Vincent University, 166 Bedford Highway, Halifax, NS B3M 2J6, Canada.
- Department of Biology, Saint Mary's University, 923 Robie Street, Halifax, NS B3H 3C3, Canada.
| | - Ashley B Martel
- Department of Biology, Saint Mary's University, 923 Robie Street, Halifax, NS B3H 3C3, Canada.
| | - Sage L Dixon
- Department of Biology, Mount Saint Vincent University, 166 Bedford Highway, Halifax, NS B3M 2J6, Canada.
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139
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Abstract
Leaf water potential regulation is a key process in whole plant and ecosystem functioning. While low water potentials induced by open stomata may initially be associated with greater CO2 supply and a higher water flux from the rhizosphere to the canopy, they also inhibit cell growth, photosynthesis and ultimately water supply. Here, we show that plants regulate their leaf water potential in an optimal manner under given constraints using a simple leaf water status regulation model and data from a global dryland leaf water potential database. Model predictions agree strongly with observations across locations and species and are further supported by experimental data. Leaf water potentials non-linearly decline with soil water potential, underlining the shift from maximizing water supply to avoiding stress with declining water availability. Our results suggest that optimal regulation of the leaf water status under varying water supply and stress tolerance is a ubiquitous property of plants in drylands. The proposed model moreover provides a novel quantitative framework describing how plants respond to short- and long-term changes in water availability and may help elaborating models of plant and ecosystem functioning.
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140
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Ratzmann G, Meinzer FC, Tietjen B. Iso/Anisohydry: Still a Useful Concept. TRENDS IN PLANT SCIENCE 2019; 24:191-194. [PMID: 30797424 DOI: 10.1016/j.tplants.2019.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 12/19/2018] [Accepted: 01/07/2019] [Indexed: 06/09/2023]
Abstract
The iso/anisohydry concept characterizes plants according to their water status regulation. Coexisting definitions and misconceptions have recently led to considerable criticism. We discuss here reasons for the misconceptions, and propose a robust definition of iso/anisohydry using the leaf turgor loss point to integrate the complex interplay of plant hydraulic traits.
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Affiliation(s)
- Gregor Ratzmann
- Freie Universität Berlin, Institute of Biology, 14195 Berlin, Germany; Freie Universität Berlin, Dahlem Centre of Plant Sciences, 14195 Berlin, Germany.
| | - Frederick C Meinzer
- US Department of Agriculture (USDA) Forest Service, Pacific Northwest Research Station, Corvallis, OR 97331, USA
| | - Britta Tietjen
- Freie Universität Berlin, Institute of Biology, 14195 Berlin, Germany; Freie Universität Berlin, Dahlem Centre of Plant Sciences, 14195 Berlin, Germany; Berlin Brandenburg Institute of Advanced Biodiversity Research (BBIB), 14195 Berlin, Germany
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141
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Yue L, Chen F, Yu K, Xiao Z, Yu X, Wang Z, Xing B. Early development of apoplastic barriers and molecular mechanisms in juvenile maize roots in response to La 2O 3 nanoparticles. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 653:675-683. [PMID: 30759593 DOI: 10.1016/j.scitotenv.2018.10.320] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 10/20/2018] [Accepted: 10/24/2018] [Indexed: 05/27/2023]
Abstract
The increasing occurrence of engineered nanoparticles (NPs) in soils may decrease water uptake in crops, followed by lower crop yield and quality. As one of the most common rare earth oxide NPs, lanthanum oxide (La2O3) NPs may inhibit the relative expressions of aquaporin genes, thus reduce water uptake. In the present study, maize plants were exposed to different La2O3 NPs concentrations (0, 5, 50 mg L-1) for 72 h and 144 h right after the first leaf extended completely. Our results revealed that water uptake was reduced by La2O3 NPs through accelerating the development of apoplastic barriers in maize roots. The level of abscisic acid, determined by using ultra high performance liquid chromatography-tandem mass spectrometry, was increased upon La2O3 NPs exposure. Furthermore, ZmPAL, ZmCCR2 and ZmCAD6, the core genes specific for biosynthesis of lignin, were up-regulated by 3-13 fold in roots exposed to 50 mg L-1 La2O3 NPs. However, ZmF5H was suppressed, indicating that lignin with S units could be excluded for the formed lignin in apoplastic barriers upon La2O3 NPs exposure. The level of essential component of apoplastic barriers - lignin was increased by 1.5-fold. The early development of apoplastic barriers was observed, and stomatal conductance and transpiration rate of La2O3 NPs-treated plants were significantly decreased by 63%-83% and 42%-86%, respectively, as compared to the control. The lignin enriched apoplastic barriers in juvenile maize thus led to the reduction of water uptake, subsequently causing significant growth inhibition. This is the first study to show early development of root apoplastic barriers upon La2O3 NPs exposure. This study will help us better understand the function of apoplastic barriers in roots in response to NPs, further providing fundamental knowledge to develop safer and more efficient agricultural nanotechnology.
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Affiliation(s)
- Le Yue
- Institute of Environmental Processes and Pollution Control, and School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China
| | - Feiran Chen
- Institute of Environmental Processes and Pollution Control, and School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China
| | - Kaiqiang Yu
- College of Environmental Science and Engineering, and Ministry of Education Key Laboratory of Marine Environment and Ecology, Ocean University of China, Qingdao 266100, China
| | - Zhenggao Xiao
- Institute of Environmental Processes and Pollution Control, and School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China
| | - Xiaoyu Yu
- College of Environmental Science and Engineering, and Ministry of Education Key Laboratory of Marine Environment and Ecology, Ocean University of China, Qingdao 266100, China
| | - Zhenyu Wang
- Institute of Environmental Processes and Pollution Control, and School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, China.
| | - Baoshan Xing
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, United States.
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142
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Villalobos-González L, Muñoz-Araya M, Franck N, Pastenes C. Controversies in Midday Water Potential Regulation and Stomatal Behavior Might Result From the Environment, Genotype, and/or Rootstock: Evidence From Carménère and Syrah Grapevine Varieties. FRONTIERS IN PLANT SCIENCE 2019; 10:1522. [PMID: 31850024 PMCID: PMC6900739 DOI: 10.3389/fpls.2019.01522] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 10/31/2019] [Indexed: 05/04/2023]
Abstract
Controversies exist regarding the iso/anisohydric continuum for classifying plant water-use strategies. Isohydricity has been argued to result from plant-environment interaction rather than it being an intrinsic property of the plant itself. Discrepancies remain regarding the degree of isohydricity (σ) of plants and their threshold for physiological responses and resistance to drought. Thus, the aim of this study was to evaluate the isohydricity of the grapevine varieties Syrah and Carménère under a non-lethal water deficit progression from veraison from two different locations, the Cachapoal Valley (CV) and Maipo Valley (MV), in central Chile and with different rootstock only in Syrah. For this purpose, the midday stem water potential (Ψmds) regulation and stomatal responses to drought, leaf traits related to pressure-volume curves, stomatal sensitivity to ABA, cavitation threshold, and photosynthetic responses were assessed. A higher atmospheric water demand was observed in the CV compared to the MV, with lower Ψmds values in the former for both varieties. Also, the σ values in Carménère were 1.11 ± 0.14 MPa MPa-1 and 0.68 ± 0.18 MPa MPa-1 in the CV and MV, respectively, and in Syrah they were 1.10 ± 0.07 MPa MPa-1 in the CV and 0.60 ± 0.10 MPa MPa-1 in the MV. Even though similar variations in σ between locations in both varieties were evident, Carménère plants showed a conserved stomatal response to Ψmds in both study sites, while those of Syrah resulted in a higher stomatal sensitivity to Ψmds in the site of lower σ. Besides the differences in seasonal weather conditions, it is likely that the different rootstock and clonal variability of each season in Syrah were able to induce coordinated changes in σ, Ψgs12, and osmotic potential at full turgor (π0). On the other hand, irrespective of the σ, and given the similarity between the π0 and Ψgs12 in leaves before drought, it seems that π0 could be a convenient tool for assessing the Ψmds threshold values posing a risk to the plants in order to aid the irrigation decision making in grapevines under controlled water deficit. Finally, water deficits in vineyards might irreversibly compromise the photosynthetic capacity of leaves.
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Affiliation(s)
- Luis Villalobos-González
- Facultad de Ciencias Agronómicas, Universidad de Chile, Santiago, Chile
- Programa de Doctorado en Ciencias Silvoagropecuarias y Veterinarias, Campus Sur Universidad de Chile, La Pintana, Chile
- *Correspondence: Luis Villalobos-González, ; Claudio Pastenes,
| | | | | | - Claudio Pastenes
- Facultad de Ciencias Agronómicas, Universidad de Chile, Santiago, Chile
- *Correspondence: Luis Villalobos-González, ; Claudio Pastenes,
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143
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Yi K, Maxwell JT, Wenzel MK, Roman DT, Sauer PE, Phillips RP, Novick KA. Linking variation in intrinsic water-use efficiency to isohydricity: a comparison at multiple spatiotemporal scales. THE NEW PHYTOLOGIST 2019; 221:195-208. [PMID: 30117538 DOI: 10.1111/nph.15384] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/06/2018] [Indexed: 06/08/2023]
Abstract
Species-specific responses of plant intrinsic water-use efficiency (iWUE) to multiple environmental drivers associated with climate change, including soil moisture (θ), vapor pressure deficit (D), and atmospheric CO2 concentration (ca ), are poorly understood. We assessed how the iWUE and growth of several species of deciduous trees that span a gradient of isohydric to anisohydric water-use strategies respond to key environmental drivers (θ, D and ca ). iWUE was calculated for individual tree species using leaf-level gas exchange and tree-ring δ13 C in wood measurements, and for the whole forest using the eddy covariance method. The iWUE of the isohydric species was generally more sensitive to environmental change than the anisohydric species was, and increased significantly with rising D during the periods of water stress. At longer timescales, the influence of ca was pronounced for isohydric tulip poplar but not for others. Trees' physiological responses to changing environmental drivers can be interpreted differently depending on the observational scale. Care should be also taken in interpreting observed or modeled trends in iWUE that do not explicitly account for the influence of D.
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Affiliation(s)
- Koong Yi
- School of Public and Environmental Affairs, Indiana University Bloomington, 1315 East Tenth Street, Bloomington, IN, 47405, USA
| | - Justin T Maxwell
- Department of Geography, Indiana University Bloomington, 701 East Kirkwood Avenue, Bloomington, IN, 47405, USA
| | - Matthew K Wenzel
- School of Public and Environmental Affairs, Indiana University Bloomington, 1315 East Tenth Street, Bloomington, IN, 47405, USA
| | - D Tyler Roman
- US Department of Agriculture Forest Service, Northern Research Station, 1831 Highway 169 East, Grand Rapids, MN, 55744, USA
| | - Peter E Sauer
- Department of Geological Science, Indiana University Bloomington, 1001 East Tenth Street, Bloomington, IN, 47405, USA
| | - Richard P Phillips
- Department of Biology, Indiana University Bloomington, 1001 East Third Street, Bloomington, IN, 47405, USA
| | - Kimberly A Novick
- School of Public and Environmental Affairs, Indiana University Bloomington, 1315 East Tenth Street, Bloomington, IN, 47405, USA
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144
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Fu X, Meinzer FC. Metrics and proxies for stringency of regulation of plant water status (iso/anisohydry): a global data set reveals coordination and trade-offs among water transport traits. TREE PHYSIOLOGY 2019; 39:122-134. [PMID: 30257009 DOI: 10.1093/treephys/tpy087] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 07/25/2018] [Indexed: 05/21/2023]
Abstract
Plants operate along a continuum of stringency of regulation of plant water potential from isohydry to anisohydry. However, most metrics and proxies of plant iso/anisohydric behavior have been developed from limited sets of site-specific experiments. Understanding the underlying mechanisms that determine species' operating ranges along this continuum, independent of site and growing conditions, remains challenging. We compiled a global database to assess the global patterns of metrics and proxies of plant iso/anisohydry and then explored some of the underlying functional traits and trade-offs associated with stringency of regulation that determines where species operate along the continuum. Our results showed that arid and semi-arid biomes were associated with greater anisohydry than more mesic biomes, and angiosperms showed marginally greater anisohydry than gymnosperms. Leaf water potential at the turgor loss point (Ψtlp) and wood density were the two most powerful proxies for ranking the degree of plant iso/anisohydry for a wide range of species and biomes. Both of these simple traits can be easily and rapidly determined, and therefore show promise for a priori mapping and understanding of the global distribution pattern of the degree of plant iso/anisohydry. Generally, the most anisohydric species had the most negative values of Ψtlp and highest wood density, greatest resistance to embolism, lowest hydraulic capacitance and lowest leaf-specific hydraulic conductivity of their branches. Wood density in particular appeared to be central to a coordinated series of traits, trade-offs and behaviors along a continuum of iso/anisohydry. Quantification of species' operating ranges along a continuum of iso/anisohydry and identification of associated trade-offs among functional traits may hold promise for mechanistic modeling of species-specific responses to the anticipated more frequent and severe droughts under global climate change scenarios.
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Affiliation(s)
- Xiaoli Fu
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
- Jiangxi Key Laboratory of Ecosystem Processes and Information, Ji'an, China
| | - Frederick C Meinzer
- USDA Forest Service, Pacific Northwest Research Station, 3200 SW Jefferson Way, Corvallis, OR, USA
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145
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Zhou S, Zhang Y, Park Williams A, Gentine P. Projected increases in intensity, frequency, and terrestrial carbon costs of compound drought and aridity events. SCIENCE ADVANCES 2019; 5:eaau5740. [PMID: 30746452 PMCID: PMC6357735 DOI: 10.1126/sciadv.aau5740] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 12/10/2018] [Indexed: 05/05/2023]
Abstract
Drought and atmospheric aridity pose large risks to ecosystem services and agricultural production. However, these factors are seldom assessed together as compound events, although they often occur simultaneously. Drought stress on terrestrial carbon uptake is characterized by soil moisture (SM) deficit and high vapor pressure deficit (VPD). We used in situ observations and 15 Earth system models to show that compound events with very high VPD and low SM occur more frequently than expected if these events were independent. These compound events are projected to become more frequent and more extreme and exert increasingly negative effects on continental productivity. Models project intensified negative effects of high VPD and low SM on vegetation productivity, with the intensification of SM exceeding those of VPD in the Northern Hemisphere. These results highlight the importance of compound extreme events and their threats for the capability of continents to act as a carbon sink.
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Affiliation(s)
- Sha Zhou
- Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027, USA
| | - Yao Zhang
- Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027, USA
| | - A. Park Williams
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
| | - Pierre Gentine
- Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027, USA
- Earth Institute, Columbia University, New York, NY 10027, USA
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146
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Guo JS, Ogle K. Antecedent soil water content and vapor pressure deficit interactively control water potential in Larrea tridentata. THE NEW PHYTOLOGIST 2019; 221:218-232. [PMID: 30129140 DOI: 10.1111/nph.15374] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 07/04/2018] [Indexed: 05/21/2023]
Abstract
Plant water potential Ψ is regulated by stomatal responses to atmospheric moisture demand D and soil water availability W, but the timescales of influence and interactions between these drivers of plant Ψ are poorly understood. Here, we quantify the effects of antecedent D and W on plant Ψ in the desert shrub Larrea tridentata. Repeated measurements of plant baseline water potential ΨB and diurnal water potential ΨD were analyzed in a Bayesian framework to evaluate the influence of antecedent D and W at daily and subdaily timescales. Both ΨB and ΨD exhibited negative, 2- to 4-d lagged responses to daily-scale D; conversely, plant ΨD responded almost instantaneously to subdaily D, though the direction of this response depended on antecedent moisture conditions. Plant ΨB and ΨD responded positively and immediately (no lag) to shallow W, which contrasts the negative, lagged (6-7 d) response to deep W. The changing sensitivity of ΨD to subdaily D highlights shifting modes of plant Ψ regulation: D effects on ΨD range from negative to neutral to positive depending on past conditions and time of day. Explicit consideration of antecedent conditions across multiple timescales can reveal important complexities in plant responses.
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Affiliation(s)
- Jessica S Guo
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011, USA
- The Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Kiona Ogle
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011, USA
- The Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, 86011, USA
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147
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Isaac-Renton M, Montwé D, Hamann A, Spiecker H, Cherubini P, Treydte K. Northern forest tree populations are physiologically maladapted to drought. Nat Commun 2018; 9:5254. [PMID: 30531998 PMCID: PMC6288165 DOI: 10.1038/s41467-018-07701-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 11/14/2018] [Indexed: 11/08/2022] Open
Abstract
Northern forests at the leading edge of their distributions may not show increased primary productivity under climate warming, being limited by climatic extremes such as drought. Looking beyond tree growth to underlying physiological mechanisms is fundamental for accurate predictions of forest responses to climate warming and drought stress. Within a 32-year genetic field trial, we analyze relative contributions of xylem plasticity and inferred stomatal response to drought tolerance in regional populations of a widespread conifer. Genetic adaptation leads to varying responses under drought. Trailing-edge tree populations produce fewer tracheids with thicker cell walls, characteristic of drought-tolerance. Stomatal response explains the moderate drought tolerance of tree populations in central areas of the species range. Growth loss of the northern population is linked to low stomatal responsiveness combined with the production of tracheids with thinner cell walls. Forests of the western boreal may therefore lack physiological adaptations necessary to tolerate drier conditions.
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Affiliation(s)
- Miriam Isaac-Renton
- Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G 2H1, Canada.
| | - David Montwé
- Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G 2H1, Canada
| | - Andreas Hamann
- Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G 2H1, Canada
| | - Heinrich Spiecker
- Chair of Forest Growth and Dendroecology, Albert-Ludwigs-Universität-Freiburg, Tennenbacherstrasse 4, 79106, Freiburg, Germany
| | - Paolo Cherubini
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, CH-8903, Birmensdorf, Switzerland
| | - Kerstin Treydte
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, CH-8903, Birmensdorf, Switzerland
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148
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Islam M, Rahman M, Bräuning A. Long-Term Hydraulic Adjustment of Three Tropical Moist Forest Tree Species to Changing Climate. FRONTIERS IN PLANT SCIENCE 2018; 9:1761. [PMID: 30564255 PMCID: PMC6288455 DOI: 10.3389/fpls.2018.01761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 11/13/2018] [Indexed: 05/06/2023]
Abstract
Xylem hydraulic adjustment to global climatic changes was reported from temperate, boreal, and Mediterranean tree species. Yet, the long-term hydraulic adjustment in tropical tree species has not been studied so far. Here we developed the first standard chronologies of three hydraulic trait variables for three South Asian moist forest tree species to analyze their long-term hydraulic responses to changing climate. Based on wood anatomical measurements, we calculated Hagen-Poiseuille hydraulically weighted vessel diameter (DH), potential specific hydraulic conductivity (KS), and vulnerability index (VX) and developed standard chronologies of these variables for Chukrasia tabularis, Toona ciliata, and Lagerstroemia speciosa which are different in their xylem structure, wood density, shade tolerance, growth rates, and habitat preferences. Bootstrap correlation analysis revealed that vapor pressure deficit (VPD) strongly positively influenced the xylem water transport capacity in C. tabularis, whereas T. ciliata was affected by both temperature and precipitation. The hydraulic conductivity of L. speciosa was mainly affected by temperature. Different adjustment strategies were observed among the species, probably due to the differences in life history strategies and xylem properties. No positive relationship of conductivity and radial growth was found, but a trade-off between hydraulic safety and efficiency was observed in all studied species.
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Affiliation(s)
- Mahmuda Islam
- Department of Geography and Geosciences, Institute of Geography, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany
- Department of Forestry and Environmental Science, Shahjalal University of Science and Technology, Sylhet, Bangladesh
| | - Mizanur Rahman
- Department of Geography and Geosciences, Institute of Geography, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany
- Department of Forestry and Environmental Science, Shahjalal University of Science and Technology, Sylhet, Bangladesh
| | - Achim Bräuning
- Department of Geography and Geosciences, Institute of Geography, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany
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149
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Eller CB, Rowland L, Oliveira RS, Bittencourt PRL, Barros FV, da Costa ACL, Meir P, Friend AD, Mencuccini M, Sitch S, Cox P. Modelling tropical forest responses to drought and El Niño with a stomatal optimization model based on xylem hydraulics. Philos Trans R Soc Lond B Biol Sci 2018; 373:20170315. [PMID: 30297470 PMCID: PMC6178424 DOI: 10.1098/rstb.2017.0315] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2018] [Indexed: 11/12/2022] Open
Abstract
The current generation of dynamic global vegetation models (DGVMs) lacks a mechanistic representation of vegetation responses to soil drought, impairing their ability to accurately predict Earth system responses to future climate scenarios and climatic anomalies, such as El Niño events. We propose a simple numerical approach to model plant responses to drought coupling stomatal optimality theory and plant hydraulics that can be used in dynamic global vegetation models (DGVMs). The model is validated against stand-scale forest transpiration (E) observations from a long-term soil drought experiment and used to predict the response of three Amazonian forest sites to climatic anomalies during the twentieth century. We show that our stomatal optimization model produces realistic stomatal responses to environmental conditions and can accurately simulate how tropical forest E responds to seasonal, and even long-term soil drought. Our model predicts a stronger cumulative effect of climatic anomalies in Amazon forest sites exposed to soil drought during El Niño years than can be captured by alternative empirical drought representation schemes. The contrasting responses between our model and empirical drought factors highlight the utility of hydraulically-based stomatal optimization models to represent vegetation responses to drought and climatic anomalies in DGVMs.This article is part of a discussion meeting issue 'The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications'.
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Affiliation(s)
- Cleiton B Eller
- College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Lucy Rowland
- College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Rafael S Oliveira
- Department of Plant Biology, Institute of Biology, UNICAMP, Campinas, Brazil
| | - Paulo R L Bittencourt
- College of Life and Environmental Sciences, University of Exeter, Exeter, UK
- Department of Plant Biology, Institute of Biology, UNICAMP, Campinas, Brazil
| | - Fernanda V Barros
- Department of Plant Biology, Institute of Biology, UNICAMP, Campinas, Brazil
| | | | - Patrick Meir
- Research School of Biology, Australian National University, Canberra, Australia
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Andrew D Friend
- Department of Geography, University of Cambridge, Cambridge, UK
| | | | - Stephen Sitch
- College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Peter Cox
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
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150
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Brum M, Gutiérrez López J, Asbjornsen H, Licata J, Pypker T, Sanchez G, Oiveira RS. ENSO effects on the transpiration of eastern Amazon trees. Philos Trans R Soc Lond B Biol Sci 2018; 373:20180085. [PMID: 30297479 PMCID: PMC6178436 DOI: 10.1098/rstb.2018.0085] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/16/2018] [Indexed: 11/12/2022] Open
Abstract
Tree transpiration is important in the recycling of precipitation in the Amazon and might be negatively affected by El Niño-Southern Oscillation (ENSO)-induced droughts. To investigate the relative importance of soil moisture deficits versus increasing atmospheric demand (VPD) and determine if these drivers exert different controls over tree transpiration during the wet season versus the dry season (DS), we conducted sap flow measurements in a primary lowland tropical forest in eastern Amazon during the most extreme ENSO-induced drought (2015/2016) recorded in the Amazon. We also assessed whether trees occupying different canopy strata contribute equally to the overall stand transpiration (Tstand). Canopy trees were the primary source of Tstand However, subcanopy trees are still important as they transpired an amount similar to other biomes around the globe. Tree water use was higher during the DS, indicating that during extreme drought trees did not reduce transpiration in response to low soil moisture. Photosynthetically active radiation and VPD exerted an overriding effect on water use patterns relative to soil moisture during extreme drought, indicating that light and atmospheric constraints play a critical role in controlling ecosystem fluxes of water. Our study highlights the importance of canopy and subcanopy trees to the regional water balance and highlights the resilience to droughts that these trees show during an extreme ENSO event.This article is part of a discussion meeting issue 'The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications'.
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Affiliation(s)
- Mauro Brum
- Department of Plant Biology, Institute of Biology, CP 6109, State University of Campinas - UNICAMP, Campinas, São Paulo 13083-970, Brazil
| | - Jose Gutiérrez López
- Earth Systems Research Center, University of New Hampshire, Durham, NH 03824, USA
| | - Heidi Asbjornsen
- Earth Systems Research Center, University of New Hampshire, Durham, NH 03824, USA
| | - Julian Licata
- Instituto Nacional de Tecnología Agropecuaria, Estación Experimental Concordia, Concordia, Entre Ríos, Argentina
| | - Thomas Pypker
- Department of Natural Resource Sciences, Thompson Rivers University, Kamloops, British Columbia, Canada V2C0C8
| | - Gilson Sanchez
- AGROPALMA Company, PA-150 Highway, No Number, Km 74, Tailândia, Pará 68695-000, Brazil
| | - Rafael S Oiveira
- Department of Plant Biology, Institute of Biology, CP 6109, State University of Campinas - UNICAMP, Campinas, São Paulo 13083-970, Brazil
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