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Chhajed SS, Wright IJ, Perez-Priego O. Theory and tests for coordination among hydraulic and photosynthetic traits in co-occurring woody species. THE NEW PHYTOLOGIST 2024. [PMID: 39044658 DOI: 10.1111/nph.19987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 05/30/2024] [Indexed: 07/25/2024]
Abstract
Co-occurring plants show wide variation in their hydraulic and photosynthetic traits. Here, we extended 'least-cost' optimality theory to derive predictions for how variation in key hydraulic traits potentially affects the cost of acquiring and using water in photosynthesis and how this, in turn, should drive variation in photosynthetic traits. We tested these ideas across 18 woody species at a temperate woodland in eastern Australia, focusing on hydraulic traits representing different aspects of plant water balance, that is storage (sapwood capacitance, CS), demand vs supply (branch leaf : sapwood area ratio, AL : AS and leaf : sapwood mass ratio and ML : MS), access to soil water (proxied by predawn leaf water potential, ΨPD) and physical strength (sapwood density, WD). Species with higher AL : AS had higher ratio of leaf-internal to ambient CO2 concentration during photosynthesis (ci : ca), a trait central to the least-cost theory framework. CS and the daily operating range of tissue water potential (∆Ψ) had an interactive effect on ci : ca. CS, WD and ΨPD were significantly correlated with each other. These results, along with those from multivariate analyses, underscored the pivotal role leaf : sapwood allocation (AL : AS), and water storage (CS) play in coordination between plant hydraulic and photosynthetic systems. This study uniquely explored the role of hydraulic traits in predicting species-specific photosynthetic variation based on optimality theory and highlights important mechanistic links within the plant carbon-water balance.
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Affiliation(s)
- Shubham S Chhajed
- School of Natural Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
- ARC Centre for Plant Success in Nature & Agriculture, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Ian J Wright
- School of Natural Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
- ARC Centre for Plant Success in Nature & Agriculture, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Oscar Perez-Priego
- Department of Forest Engineering, University of Córdoba, Campus de Rabanales, Crta. N-IV km. 396, C.P. 14071, Córdoba, Spain
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Thompson RA. A neutral theory of plant carbon allocation. TREE PHYSIOLOGY 2024; 44:tpad151. [PMID: 38102767 DOI: 10.1093/treephys/tpad151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 12/10/2023] [Indexed: 12/17/2023]
Abstract
How plants use the carbon they gain from photosynthesis remains a key area of study among plant ecologists. Although numerous theories have been presented throughout the years, the field lacks a clear null model. To fill this gap, I have developed the first null model, or neutral theory, of plant carbon allocation using probability theory, plant biochemistry and graph theory at the level of a leaf. Neutral theories have been used to establish a null hypothesis in molecular evolution and community assembly to describe how much of an ecological phenomenon can be described by chance alone. Here, the aim of a neutral theory of plant carbon allocation is to ask: how is carbon partitioned between sinks if one assumes plants do not prioritize certain sinks over others? Using the biochemical network of plant carbon metabolism, I show that, if allocation was strictly random, carbon is more likely to be allocated to storage, defense, respiration and finally growth. This 'neutral hierarchy' suggests that a sink's biochemical distance from photosynthesis plays an important role in carbon allocation patterns, highlighting the potentially adaptive role of this biochemical network for plant survival in variable environments. A brief simulation underscores that our ability to measure the carbon allocation from photosynthesis to a given sink is unreliable due to simple probabilistic rules. While neutral theory may not explain all patterns of carbon allocation, its utility is in the minimal assumptions and role as a null model against which future data should be tested.
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Affiliation(s)
- R Alex Thompson
- School of the Environment, Washington State University, Pullman, WA 99164, USA
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de Tomás Marín S, Galán Díaz J, Rodríguez-Calcerrada J, Prieto I, de la Riva EG. Linking functional composition moments of the sub-Mediterranean ecotone with environmental drivers. FRONTIERS IN PLANT SCIENCE 2023; 14:1303022. [PMID: 38143583 PMCID: PMC10748396 DOI: 10.3389/fpls.2023.1303022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 11/17/2023] [Indexed: 12/26/2023]
Abstract
Introduction Functional trait-based approaches are extensively applied to the study of mechanisms governing community assembly along environmental gradients. These approaches have been classically based on studying differences in mean values among species, but there is increasing recognition that alternative metrics of trait distributions should be considered to decipher the mechanisms determining community assembly and species coexistence. Under this framework, the main aim of this study is to unravel the effects of environmental conditions as drivers of plant community assembly in sub-Mediterranean ecotones. Methods We set 60 plots in six plant communities of a sub-Mediterranean forest in Central Spain, and measured key above- and belowground functional traits in 411 individuals belonging to 19 species, along with abiotic variables. We calculated community-weighted mean (CWM), skewness (CWS) and kurtosis (CWK) of three plant dimensions, and used maximum likelihood techniques to analyze how variation in these functional community traits was driven by abiotic factors. Additionally, we estimated the relative contribution of intraspecific trait variability and species turnover to variation in CWM. Results and discussion The first three axes of variation of the principal component analyses were related to three main plant ecological dimensions: Leaf Economics Spectrum, Root Economics Spectrum and plant hydraulic architecture, respectively. Type of community was the most important factor determining differences in the functional structure among communities, as compared to the role of abiotic variables. We found strong differences among communities in their CWMs in line with their biogeographic origin (Eurosiberian vs Mediterranean), while differences in CWS and CWK indicate different trends in the functional structure among communities and the coexistence of different functional strategies, respectively. Moreover, changes in functional composition were primarily due to intraspecific variability. Conclusion We observed a high number of strategies in the forest with the different communities spreading along the acquisitive-conservative axis of resource-use, partly matching their Eurosiberian-Mediterranean nature, respectively. Intraspecific trait variability, rather than species turnover, stood as the most relevant factor when analyzing functional changes and assembly patterns among communities. Altogether, our data support the notion that ecotones are ecosystems where relatively minor environmental shifts may result in changes in plant and functional composition.
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Affiliation(s)
- Sergio de Tomás Marín
- Department of Ecology, Brandenburgische Technische Universität Cottbus-Senftenberg, Cottbus, Germany
| | - Javier Galán Díaz
- Department of Pharmacology, Pharmacognosy and Botany, Faculty of Pharmacy, Universidad Complutense de Madrid, Madrid, Spain
| | - Jesús Rodríguez-Calcerrada
- Functioning of Forest Systems in a Changing Environment Research Group, Universidad Politécnica de Madrid, Madrid, Spain
| | - Iván Prieto
- Ecology Department, Faculty of Biology and Environmental Sciences, Universidad de León, León, Spain
| | - Enrique G. de la Riva
- Department of Ecology, Brandenburgische Technische Universität Cottbus-Senftenberg, Cottbus, Germany
- Ecology Department, Faculty of Biology and Environmental Sciences, Universidad de León, León, Spain
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Moran ME, Aparecido LMT, Koepke DF, Cooper HF, Doughty CE, Gehring CA, Throop HL, Whitham TG, Allan GJ, Hultine KR. Limits of thermal and hydrological tolerance in a foundation tree species (Populus fremontii) in the desert southwestern United States. THE NEW PHYTOLOGIST 2023; 240:2298-2311. [PMID: 37680030 DOI: 10.1111/nph.19247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 08/05/2023] [Indexed: 09/09/2023]
Abstract
Populus fremontii is among the most dominant, and ecologically important riparian tree species in the western United States and can thrive in hyper-arid riparian corridors. Yet, P. fremontii forests have rapidly declined over the last decade, particularly in places where temperatures sometimes exceed 50°C. We evaluated high temperature tolerance of leaf metabolism, leaf thermoregulation, and leaf hydraulic function in eight P. fremontii populations spanning a 5.3°C mean annual temperature gradient in a well-watered common garden, and at source locations throughout the lower Colorado River Basin. Two major results emerged. First, despite having an exceptionally high Tcrit (the temperature at which Photosystem II is disrupted) relative to other tree taxa, recent heat waves exceeded Tcrit , requiring evaporative leaf cooling to maintain leaf-to-air thermal safety margins. Second, in midsummer, genotypes from the warmest locations maintained lower midday leaf temperatures, a higher midday stomatal conductance, and maintained turgor pressure at lower water potentials than genotypes from more temperate locations. Taken together, results suggest that under well-watered conditions, P. fremontii can regulate leaf temperature below Tcrit along the warm edge of its distribution. Nevertheless, reduced Colorado River flows threaten to lower water tables below levels needed for evaporative cooling during episodic heat waves.
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Affiliation(s)
- Madeline E Moran
- School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Luiza M T Aparecido
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, 85287, USA
| | - Dan F Koepke
- Department of Research, Conservation and Collections, Desert Botanical Garden, Phoenix, AZ, 85008, USA
| | - Hillary F Cooper
- Department of Biological Sciences and Center for Adaptable Western Landscapes, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Christopher E Doughty
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Catherine A Gehring
- Department of Biological Sciences and Center for Adaptable Western Landscapes, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Heather L Throop
- School of Life Sciences, Arizona State University, Tempe, AZ, 85287, USA
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, 85287, USA
| | - Thomas G Whitham
- Department of Biological Sciences and Center for Adaptable Western Landscapes, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Gerard J Allan
- Department of Biological Sciences and Center for Adaptable Western Landscapes, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Kevin R Hultine
- Department of Research, Conservation and Collections, Desert Botanical Garden, Phoenix, AZ, 85008, USA
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Zhu LW, Zhao P. Climate-driven sapwood-specific hydraulic conductivity and the Huber value but not leaf-specific hydraulic conductivity on a global scale. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 857:159334. [PMID: 36220474 DOI: 10.1016/j.scitotenv.2022.159334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/27/2022] [Accepted: 10/06/2022] [Indexed: 06/16/2023]
Abstract
Efficient water transport is crucial for plant growth and survival. Plant hydraulic conductivity varies between functional groups and biomes and is strongly influenced by changing environmental conditions. However, correlations of conductivity-related hydraulic traits with climatic variables are not fully understood, preventing clarification of plant form and function under climate change scenarios. By compiling leaf-specific hydraulic conductivity (KL), sapwood-specific hydraulic conductivity (Ks), and Huber values (Hv, sapwood area to leaf area ratio) along with climatic variables including mean annual temperature (MAT), mean annual precipitation (MAP) and aridity index (AI) for 428 species across a wide range of plant functional types (PFTs) and biomes at a global scale, we found greater variability of KL within PFTs and biomes than across PFTs and biomes. Interaction effects between PFTs and biomes on KL and Ks were found. The interaction between MAT and MAP played a significant role in Ks and Hv (t = 3.89, P < 0.001 for Ks and t = -5.77, P < 0.001 for Hv). With increasing AI, Ks increased and Hv decreased. KL was not influenced by the investigated climatic variables. Our study provides a better understanding of the dynamics of hydraulic structure and function across functional groups and biomes and of the abiotic drivers of their large-scale variations.
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Affiliation(s)
- Li-Wei Zhu
- South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Ping Zhao
- South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
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Xu GQ, Kandlikar GS, Vaz MC. Evolutionary lability underlies drought adaptation of Australian shrubs along aridity gradients. FRONTIERS IN PLANT SCIENCE 2022; 13:949531. [PMID: 36275606 PMCID: PMC9585297 DOI: 10.3389/fpls.2022.949531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
Leaf drought tolerance traits influence plant survival in water deficit conditions, and these traits are influenced by both the plant's evolutionary history and the environment in which the plant is currently growing. However, due to the substantial phenotypic plasticity in leaf traits, we still do not know to what degree variation in leaf traits is governed by species' phylogenetic history or by their environment. To explore this question, we re-examined a drought tolerance dataset from 37 native Australian shrub species with varying climate origins growing in a common garden located in Melbourne, Australia. We previously measured seven leaf morphophysiological traits, and here, we estimated how phylogenetically conserved these traits are. We quantified phylogeny and the strength of correlation between the morphological traits and physiological traits before and after accounting for shared phylogenetic history. We also evaluated the relationship between species' leaf traits and the climate of their native ranges. We present three main findings: (a) most leaf drought tolerance traits had weak phylogenetic signals, which is consistent with the convergent evolution of these traits. (b) There is weak but consistent coordination between distinct leaf drought tolerance traits, which can be masked due to species' phylogenetic histories. (c) Leaf drought tolerance traits show strong correlations with the climate of species' origins, and this relationship is only weakly impacted by phylogenetic signals. Therefore, the role of phylogeny on the coordination among leaf functional traits and their links to climate were limited. A better understanding of trait-environment relationships might be more pivotal than understanding the evolution of these traits for improving the predictions of species' response to climate change-type drought, especially for shrub species that span substantial aridity gradients.
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Affiliation(s)
- Gui-Qing Xu
- State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China
| | - Gaurav S. Kandlikar
- Division of Biological Sciences and Division of Plant Sciences, University of Missouri, Columbia, MO, United States
| | - Marcel C. Vaz
- Wilkes University, Institute for Environmental Science and Sustainability, Wilkes-Barre, PA, United States
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Dulamsuren C, Hauck M. Drought stress mitigation by nitrogen in boreal forests inferred from stable isotopes. GLOBAL CHANGE BIOLOGY 2021; 27:5211-5224. [PMID: 34309985 DOI: 10.1111/gcb.15813] [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: 06/01/2021] [Revised: 07/21/2021] [Accepted: 07/21/2021] [Indexed: 06/13/2023]
Abstract
Forest growth in most parts of the boreal zone is originally limited by low temperatures and low nitrogen availability. Due to the rapid climate warming at high latitudes, an increasing forest area is switching to drought limitation, especially in continental and southern parts of the boreal forest. Studies addressing this issue were mostly dendrochronological and remote-sensing analyses focusing on climatic effects, but not answering the question whether drought is effective alone or in combination with nitrogen shortage at limiting the forests' productivity and vitality. Here we show in a case study from larch forests of Mongolia with a combination of stable isotope analyses, tree-ring analysis and bioindication of the local variability of livestock densities using epiphytic lichens that, in the studied highly drought-prone forests at the southern fringe of the boreal forest in Inner Asia, the trees' vulnerability to drought is modified by nitrogen fertilization from livestock kept in the vicinity and the edge of the forests. The most likely mechanism behind this drought-nitrogen interaction is the reduction of stomatal conductance, which is known to be induced by low nitrogen levels in plants. Nitrogen fertilization by the livestock could, thus, shorten the times of stomatal closure and thereby increase tree growth, which we measured as radial stem increment. Even though the underlying mechanisms, which were so far examined in angiosperms, should be experimentally tested for conifers, our results indicate that focusing on water alone is not enough to understand the climate change response of drought-limited boreal forests.
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Affiliation(s)
| | - Markus Hauck
- Applied Vegetation Ecology, University of Freiburg, Freiburg, Germany
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Guillemot J, Asensio V, Bordron B, Nouvellon Y, le Maire G, Bouillet JP, Domec JC, Delgado Rojas JS, Abreu-Junior CH, Battie-Laclau P, Cornut I, Germon A, De Moraes Gonçalves JL, Robin A, Laclau JP. Increased hydraulic constraints in Eucalyptus plantations fertilized with potassium. PLANT, CELL & ENVIRONMENT 2021; 44:2938-2950. [PMID: 34033133 DOI: 10.1111/pce.14102] [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: 01/21/2021] [Accepted: 05/20/2021] [Indexed: 06/12/2023]
Abstract
Fertilization is commonly used to increase growth in forest plantations, but it may also affect tree water relations and responses to drought. Here, we measured changes in biomass, transpiration, sapwood-to-leaf area ratio (As :Al ) and sap flow driving force (ΔΨ) during the 6-year rotation of tropical plantations of Eucalyptus grandis under controlled conditions for throughfall and potassium (K) fertilization. K fertilization increased final tree height by 8 m. Throughfall exclusion scarcely affected tree functioning because of deep soil water uptake. Tree growth increased in K-supplied plots and remained stable in K-depleted plots as tree height increased, while growth per unit leaf area increased in all plots. Stand transpiration and hydraulic conductance standardized per leaf area increased with height in K-depleted plots, but remained stable or decreased in K-supplied plots. Greater Al in K-supplied plots increased the hydraulic constraints on water use. This involved a direct mechanism through halved As :Al in K-supplied plots relative to K-depleted plots, and an indirect mechanism through deteriorated water status in K-supplied plots, which prevented the increase in ΔΨ with tree height. K fertilization in tropical plantations reduces the hydraulic compensation to growth, which could increase the risk of drought-induced dieback under climate change.
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Affiliation(s)
- Joannès Guillemot
- CIRAD, UMR Eco&Sols, Montpellier, France
- Eco&Sols, Univ Montpellier, CIRAD, INRAe, IRD, Montpellier SupAgro, Montpellier, France
- Department of Forest Sciences, Universidade de São Paulo, "Luiz de Queiroz" College of Agriculture (USP-ESALQ), Piracicaba, Brazil
| | - Verónica Asensio
- Department of Forest Sciences, Universidade de São Paulo, "Luiz de Queiroz" College of Agriculture (USP-ESALQ), Piracicaba, Brazil
- Center of Nuclear Energy in Agriculture, Universidade de São Paulo (USP-CENA), Piracicaba, Brazil
- Edafotec SL, Vigo, Spain
| | - Bruno Bordron
- CIRAD, UMR Eco&Sols, Montpellier, France
- Eco&Sols, Univ Montpellier, CIRAD, INRAe, IRD, Montpellier SupAgro, Montpellier, France
- Department of Forest Sciences, Universidade de São Paulo, "Luiz de Queiroz" College of Agriculture (USP-ESALQ), Piracicaba, Brazil
| | - Yann Nouvellon
- CIRAD, UMR Eco&Sols, Montpellier, France
- Eco&Sols, Univ Montpellier, CIRAD, INRAe, IRD, Montpellier SupAgro, Montpellier, France
- Department of Forest Sciences, Universidade de São Paulo, "Luiz de Queiroz" College of Agriculture (USP-ESALQ), Piracicaba, Brazil
| | - Guerric le Maire
- CIRAD, UMR Eco&Sols, Montpellier, France
- Eco&Sols, Univ Montpellier, CIRAD, INRAe, IRD, Montpellier SupAgro, Montpellier, France
- NIPE, UNICAMP, Campinas, Brazil
| | - Jean-Pierre Bouillet
- CIRAD, UMR Eco&Sols, Montpellier, France
- Eco&Sols, Univ Montpellier, CIRAD, INRAe, IRD, Montpellier SupAgro, Montpellier, France
- Department of Forest Sciences, Universidade de São Paulo, "Luiz de Queiroz" College of Agriculture (USP-ESALQ), Piracicaba, Brazil
| | - Jean-Christophe Domec
- Bordeaux Sciences Agro, UMR INRAe-ISPA 1391, Gradignan, France
- Nicholas School of the Environment, Duke University, Durham, North Carolina, USA
| | - Juan Sinforiano Delgado Rojas
- Department of Forest Sciences, Universidade de São Paulo, "Luiz de Queiroz" College of Agriculture (USP-ESALQ), Piracicaba, Brazil
| | | | - Patricia Battie-Laclau
- Department of Forest Sciences, Universidade de São Paulo, "Luiz de Queiroz" College of Agriculture (USP-ESALQ), Piracicaba, Brazil
- Center of Nuclear Energy in Agriculture, Universidade de São Paulo (USP-CENA), Piracicaba, Brazil
| | - Ivan Cornut
- CIRAD, UMR Eco&Sols, Montpellier, France
- Eco&Sols, Univ Montpellier, CIRAD, INRAe, IRD, Montpellier SupAgro, Montpellier, France
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
| | - Amandine Germon
- CIRAD, UMR Eco&Sols, Montpellier, France
- Eco&Sols, Univ Montpellier, CIRAD, INRAe, IRD, Montpellier SupAgro, Montpellier, France
- School of Agricultural Sciences, UNESP-São Paulo State University, Botucatu, Brazil
| | | | - Agnès Robin
- CIRAD, UMR Eco&Sols, Montpellier, France
- Eco&Sols, Univ Montpellier, CIRAD, INRAe, IRD, Montpellier SupAgro, Montpellier, France
- Department of Forest Sciences, Universidade de São Paulo, "Luiz de Queiroz" College of Agriculture (USP-ESALQ), Piracicaba, Brazil
- School of Agricultural Sciences, UNESP-São Paulo State University, Botucatu, Brazil
| | - Jean-Paul Laclau
- CIRAD, UMR Eco&Sols, Montpellier, France
- Eco&Sols, Univ Montpellier, CIRAD, INRAe, IRD, Montpellier SupAgro, Montpellier, France
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A multiple-trait analysis of ecohydrological acclimatisation in a dryland phreatophytic shrub. Oecologia 2021; 196:1179-1193. [PMID: 34331567 PMCID: PMC8367881 DOI: 10.1007/s00442-021-04993-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 07/19/2021] [Indexed: 10/26/2022]
Abstract
Water is the main limiting factor for groundwater-dependent ecosystems (GDEs) in drylands. Predicted climate change (precipitation reductions and temperature increases) and anthropogenic activities such as groundwater drawdown jeopardise the functioning of these ecosystems, presenting new challenges for their management. We developed a trait-based analysis to examine the spatiotemporal variability in the ecophysiology of Ziziphus lotus, a long-lived phreatophyte that dominates one of the few terrestrial GDEs of semiarid regions in Europe. We assessed morpho-functional traits and stem water potential along a naturally occurring gradient of depth-to-groundwater (DTGW, 2-25 m) in a coastal aquifer, and throughout the species-growing season. Increasing DTGW and salinity negatively affected photosynthetic and transpiration rates, increasing plant water stress (lower predawn and midday water potential), and positively affected Huber value (sapwood cross-sectional area per leaf area), reducing leaf area and likely, plant hydraulic demand. However, the species showed greater salt-tolerance at shallow depths. Despite groundwater characteristics, higher atmospheric evaporative demand in the study area, which occurred in summer, fostered higher transpiration rates and water stress, and promoted carbon assimilation and water loss more intensively at shallow water tables. This multiple-trait analysis allowed us to identify plant ecophysiological thresholds related to the increase in salinity, but mostly in DTGW (13 m), and in the evaporative demand during the growing season. These findings highlight the existence of tipping points in the functioning of a long-lived phreatophyte in drylands and can contribute to the sustainable management of GDEs in southern Europe, paving the way for further studies on phreatophytic species.
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Oyanoghafo OO, O’ Brien C, Choat B, Tissue D, Rymer PD. Vulnerability to xylem cavitation of Hakea species (Proteaceae) from a range of biomes and life histories predicted by climatic niche. ANNALS OF BOTANY 2021; 127:909-918. [PMID: 33606015 PMCID: PMC8225280 DOI: 10.1093/aob/mcab020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 02/17/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND AND AIMS Extreme drought conditions across the globe are impacting biodiversity, with serious implications for the persistence of native species. However, quantitative data on physiological tolerance are not available for diverse flora to inform conservation management. We quantified physiological resistance to cavitation in the diverse Hakea genus (Proteaceae) to test predictions based on climatic origin, life history and functional traits. METHODS We sampled terminal branches of replicate plants of 16 species in a common garden. Xylem cavitation was induced in branches under varying water potentials (tension) in a centrifuge, and the tension generating 50 % loss of conductivity (stem P50) was characterized as a metric for cavitation resistance. The same branches were used to estimate plant functional traits, including wood density, specific leaf area and Huber value (sap flow area to leaf area ratio). KEY RESULTS There was significant variation in stem P50 among species, which was negatively associated with the species climate origin (rainfall and aridity). Cavitation resistance did not differ among life histories; however, a drought avoidance strategy with terete leaf form and greater Huber value may be important for species to colonize and persist in the arid biome. CONCLUSIONS This study highlights climate (rainfall and aridity), rather than life history and functional traits, as the key predictor of variation in cavitation resistance (stem P50). Rainfall for species origin was the best predictor of cavitation resistance, explaining variation in stem P50, which appears to be a major determinant of species distribution. This study also indicates that stem P50 is an adaptive trait, genetically determined, and hence reliable and robust for predicting species vulnerability to climate change. Our findings will contribute to future prediction of species vulnerability to drought and adaptive management under climate change.
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Affiliation(s)
- Osazee O Oyanoghafo
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2751,Australia
- Department of Plant Biology and Biotechnology, Faculty of Life Sciences, University of Benin, Benin City, Nigeria
| | - Corey O’ Brien
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2751,Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2751,Australia
| | - David Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2751,Australia
| | - Paul D Rymer
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2751,Australia
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Potkay A, Trugman AT, Wang Y, Venturas MD, Anderegg WRL, Mattos CRC, Fan Y. Coupled whole-tree optimality and xylem hydraulics explain dynamic biomass partitioning. THE NEW PHYTOLOGIST 2021; 230:2226-2245. [PMID: 33521942 DOI: 10.1111/nph.17242] [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: 07/23/2020] [Accepted: 01/25/2021] [Indexed: 06/12/2023]
Abstract
Trees partition biomass in response to resource limitation and physiological activity. It is presumed that these strategies evolved to optimize some measure of fitness. If the optimization criterion can be specified, then allometry can be modeled from first principles without prescribed parameterization. We present the Tree Hydraulics and Optimal Resource Partitioning (THORP) model, which optimizes allometry by estimating allocation fractions to organs as proportional to their ratio of marginal gain to marginal cost, where gain is net canopy photosynthesis rate, and costs are senescence rates. Root total biomass and profile shape are predicted simultaneously by a unified optimization. Optimal partitioning is solved by a numerically efficient analytical solution. THORP's predictions agree with reported tree biomass partitioning in response to size, water limitations, elevated CO2 and pruning. Roots were sensitive to soil moisture profiles and grew down to the groundwater table when present. Groundwater buffered against water stress regardless of meteorology, stabilizing allometry and root profiles as deep as c. 30 m. Much of plant allometry can be explained by hydraulic considerations. However, nutrient limitations cannot be fully ignored. Rooting mass and profiles were synchronized with hydrological conditions and groundwater even at considerable depths, illustrating that the below ground shapes whole-tree allometry.
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Affiliation(s)
- Aaron Potkay
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ, 08854, USA
| | - Anna T Trugman
- Department of Geography, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Yujie Wang
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Martin D Venturas
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - William R L Anderegg
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - Caio R C Mattos
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ, 08854, USA
| | - Ying Fan
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ, 08854, USA
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12
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Skiadaresis G, Schwarz J, Stahl K, Bauhus J. Groundwater extraction reduces tree vitality, growth and xylem hydraulic capacity in Quercus robur during and after drought events. Sci Rep 2021; 11:5149. [PMID: 33664306 PMCID: PMC7970862 DOI: 10.1038/s41598-021-84322-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 02/15/2021] [Indexed: 01/31/2023] Open
Abstract
Climate change is expected to pose major direct and indirect threats to groundwater-dependent forest ecosystems. Forests that concurrently experience increased rates of water extraction may face unprecedented exposure to droughts. Here, we examined differences in stem growth and xylem hydraulic architecture of 216 oak trees from sites with contrasting groundwater availability, including sites where groundwater extraction has led to reduced water availability for trees over several decades. We expected reduced growth and xylem hydraulic capacity for trees at groundwater extraction sites both under normal and unfavourable growing conditions. Compared to sites without extraction, trees at sites with groundwater extraction showed reduced growth and hydraulic conductivity both during periods of moderate and extremely low soil water availability. Trees of low vigour, which were more frequent at sites with groundwater extraction, were not able to recover growth and hydraulic capacity following drought, pointing to prolonged drought effects. Long-term water deficit resulting in reduced CO2 assimilation and hydraulic capacity after drought are very likely responsible for observed reductions in tree vitality at extraction sites. Our results demonstrate that groundwater access maintains tree function and resilience to drought and is therefore important for tree health in the context of climate change.
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Affiliation(s)
- Georgios Skiadaresis
- Chair of Silviculture, Institute of Forest Sciences, University of Freiburg, Tennenbacherstrasse 4, 79085, Freiburg im Breisgau, Germany.
| | - Julia Schwarz
- Chair of Silviculture, Institute of Forest Sciences, University of Freiburg, Tennenbacherstrasse 4, 79085, Freiburg im Breisgau, Germany
| | - Kerstin Stahl
- Chair of Environmental Hydrological Systems, University of Freiburg, Friedrichstrasse 39, 79098, Freiburg im Breisgau, Germany
| | - Jürgen Bauhus
- Chair of Silviculture, Institute of Forest Sciences, University of Freiburg, Tennenbacherstrasse 4, 79085, Freiburg im Breisgau, Germany
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13
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De Kauwe MG, Medlyn BE, Ukkola AM, Mu M, Sabot MEB, Pitman AJ, Meir P, Cernusak LA, Rifai SW, Choat B, Tissue DT, Blackman CJ, Li X, Roderick M, Briggs PR. Identifying areas at risk of drought-induced tree mortality across South-Eastern Australia. GLOBAL CHANGE BIOLOGY 2020; 26:5716-5733. [PMID: 32512628 DOI: 10.1111/gcb.15215] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 05/25/2020] [Indexed: 06/11/2023]
Abstract
South-East Australia has recently been subjected to two of the worst droughts in the historical record (Millennium Drought, 2000-2009 and Big Dry, 2017-2019). Unfortunately, a lack of forest monitoring has made it difficult to determine whether widespread tree mortality has resulted from these droughts. Anecdotal observations suggest the Big Dry may have led to more significant tree mortality than the Millennium drought. Critically, to be able to robustly project future expected climate change effects on Australian vegetation, we need to assess the vulnerability of Australian trees to drought. Here we implemented a model of plant hydraulics into the Community Atmosphere Biosphere Land Exchange (CABLE) land surface model. We parameterized the drought response behaviour of five broad vegetation types, based on a common garden dry-down experiment with species originating across a rainfall gradient (188-1,125 mm/year) across South-East Australia. The new hydraulics model significantly improved (~35%-45% reduction in root mean square error) CABLE's previous predictions of latent heat fluxes during periods of water stress at two eddy covariance sites in Australia. Landscape-scale predictions of the greatest percentage loss of hydraulic conductivity (PLC) of about 40%-60%, were broadly consistent with satellite estimates of regions of the greatest change in both droughts. In neither drought did CABLE predict that trees would have reached critical PLC in widespread areas (i.e. it projected a low mortality risk), although the model highlighted critical levels near the desert regions of South-East Australia where few trees live. Overall, our experimentally constrained model results imply significant resilience to drought conferred by hydraulic function, but also highlight critical data and scientific gaps. Our approach presents a promising avenue to integrate experimental data and make regional-scale predictions of potential drought-induced hydraulic failure.
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Affiliation(s)
- Martin G De Kauwe
- ARC Centre of Excellence for Climate Extremes, Sydney, NSW, Australia
- Climate Change Research Centre, University of New South Wales, Sydney, NSW, Australia
- Evolution & Ecology Research Centre, University of New South Wales, Sydney, NSW, Australia
| | - Belinda E Medlyn
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Anna M Ukkola
- ARC Centre of Excellence for Climate Extremes, Sydney, NSW, Australia
- Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia
| | - Mengyuan Mu
- ARC Centre of Excellence for Climate Extremes, Sydney, NSW, Australia
- Climate Change Research Centre, University of New South Wales, Sydney, NSW, Australia
| | - Manon E B Sabot
- ARC Centre of Excellence for Climate Extremes, Sydney, NSW, Australia
- Climate Change Research Centre, University of New South Wales, Sydney, NSW, Australia
- Evolution & Ecology Research Centre, University of New South Wales, Sydney, NSW, Australia
| | - Andrew J Pitman
- ARC Centre of Excellence for Climate Extremes, Sydney, NSW, Australia
- Climate Change Research Centre, University of New South Wales, Sydney, NSW, Australia
| | - Patrick Meir
- Research School of Biology, The Australian National University, Acton, ACT, Australia
- School of Geosciences, University of Edinburgh, Edinburgh, UK
| | - Lucas A Cernusak
- College of Science and Engineering, James Cook University, Cairns, Qld, Australia
| | - Sami W Rifai
- Climate Change Research Centre, University of New South Wales, Sydney, NSW, Australia
| | - Brendan Choat
- 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
| | - Chris J Blackman
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Ximeng Li
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Michael Roderick
- ARC Centre of Excellence for Climate Extremes, Sydney, NSW, Australia
- Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia
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14
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Pritzkow C, Williamson V, Szota C, Trouvé R, Arndt SK. Phenotypic plasticity and genetic adaptation of functional traits influences intra-specific variation in hydraulic efficiency and safety. TREE PHYSIOLOGY 2020; 40:215-229. [PMID: 31860729 DOI: 10.1093/treephys/tpz121] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 09/24/2019] [Accepted: 11/14/2019] [Indexed: 06/10/2023]
Abstract
Understanding which hydraulic traits are under genetic control and/or are phenotypically plastic is essential in understanding how tree species will respond to rapid shifts in climate. We quantified hydraulic traits in Eucalyptus obliqua L'Her. across a precipitation gradient in the field to describe (i) trait variation in relation to long-term climate and (ii) the short-term (seasonal) ability of traits to adjust (i.e., phenotypic plasticity). Seedlings from each field population were raised under controlled conditions to assess (iii) which traits are under strong genetic control. In the field, drier populations had smaller leaves with anatomically thicker xylem vessel walls, a lower leaf hydraulic vulnerability and a lower water potential at turgor loss point, which likely confers higher hydraulic safety. Traits such as the water potential at turgor loss point and ratio of sapwood to leaf area (Huber value) showed significant adjustment from wet to dry conditions in the field, indicating phenotypic plasticity and importantly, the ability to increase hydraulic safety in the short term. In the nursery, seedlings from drier populations had smaller leaves and a lower leaf hydraulic vulnerability, suggesting that key traits associated with hydraulic safety are under strong genetic control. Overall, our study suggests a strong genetic control over traits associated with hydraulic safety, which may compromise the survival of wet-origin populations in drier future climates. However, phenotypic plasticity in physiological and morphological traits may confer sufficient hydraulic safety to facilitate genetic adaptation.
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Affiliation(s)
- Carola Pritzkow
- School of Ecosystem and Forest Sciences, University of Melbourne, 500 Yarra Blvd Burnley, VIC 3121, Australia
| | - Virginia Williamson
- School of Ecosystem and Forest Sciences, University of Melbourne, 500 Yarra Blvd Burnley, VIC 3121, Australia
| | - Christopher Szota
- School of Ecosystem and Forest Sciences, University of Melbourne, 500 Yarra Blvd Burnley, VIC 3121, Australia
| | - Raphael Trouvé
- School of Ecosystem and Forest Sciences, University of Melbourne, 500 Yarra Blvd Burnley, VIC 3121, Australia
| | - Stefan K Arndt
- School of Ecosystem and Forest Sciences, University of Melbourne, 500 Yarra Blvd Burnley, VIC 3121, Australia
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15
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Sperry JS, Venturas MD, Todd HN, Trugman AT, Anderegg WRL, Wang Y, Tai X. The impact of rising CO 2 and acclimation on the response of US forests to global warming. Proc Natl Acad Sci U S A 2019; 116:25734-25744. [PMID: 31767760 PMCID: PMC6926066 DOI: 10.1073/pnas.1913072116] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The response of forests to climate change depends in part on whether the photosynthetic benefit from increased atmospheric CO2 (∆Ca = future minus historic CO2) compensates for increased physiological stresses from higher temperature (∆T). We predicted the outcome of these competing responses by using optimization theory and a mechanistic model of tree water transport and photosynthesis. We simulated current and future productivity, stress, and mortality in mature monospecific stands with soil, species, and climate sampled from 20 continental US locations. We modeled stands with and without acclimation to ∆Ca and ∆T, where acclimated forests adjusted leaf area, photosynthetic capacity, and stand density to maximize productivity while avoiding stress. Without acclimation, the ∆Ca-driven boost in net primary productivity (NPP) was compromised by ∆T-driven stress and mortality associated with vascular failure. With acclimation, the ∆Ca-driven boost in NPP and stand biomass (C storage) was accentuated for cooler futures but negated for warmer futures by a ∆T-driven reduction in NPP and biomass. Thus, hotter futures reduced forest biomass through either mortality or acclimation. Forest outcomes depended on whether projected climatic ∆Ca/∆T ratios were above or below physiological thresholds that neutralized the negative impacts of warming. Critically, if forests do not acclimate, the ∆Ca/∆T must be above ca 89 ppm⋅°C-1 to avoid chronic stress, a threshold met by 55% of climate projections. If forests do acclimate, the ∆Ca/∆T must rise above ca 67 ppm⋅°C-1 for NPP and biomass to increase, a lower threshold met by 71% of projections.
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Affiliation(s)
- John S Sperry
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112
| | - Martin D Venturas
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112;
| | - Henry N Todd
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112
| | - Anna T Trugman
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112
- Department of Geography, University of California, Santa Barbara, CA 93106
| | | | - Yujie Wang
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112
| | - Xiaonan Tai
- Department of Geology and Geophysics, University of Utah, Salt Lake City, UT 84112
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16
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Trugman AT, Anderegg LDL, Wolfe BT, Birami B, Ruehr NK, Detto M, Bartlett MK, Anderegg WRL. Climate and plant trait strategies determine tree carbon allocation to leaves and mediate future forest productivity. GLOBAL CHANGE BIOLOGY 2019; 25:3395-3405. [PMID: 31070834 DOI: 10.1111/gcb.14680] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 05/02/2019] [Accepted: 05/04/2019] [Indexed: 06/09/2023]
Abstract
Forest leaf area has enormous leverage on the carbon cycle because it mediates both forest productivity and resilience to climate extremes. Despite widespread evidence that trees are capable of adjusting to changes in environment across both space and time through modifying carbon allocation to leaves, many vegetation models use fixed carbon allocation schemes independent of environment, which introduces large uncertainties into predictions of future forest responses to atmospheric CO2 fertilization and anthropogenic climate change. Here, we develop an optimization-based model, whereby tree carbon allocation to leaves is an emergent property of environment and plant hydraulic traits. Using a combination of meta-analysis, observational datasets, and model predictions, we find strong evidence that optimal hydraulic-carbon coupling explains observed patterns in leaf allocation across large environmental and CO2 concentration gradients. Furthermore, testing the sensitivity of leaf allocation strategy to a diversity in hydraulic and economic spectrum physiological traits, we show that plant hydraulic traits in particular have an enormous impact on the global change response of forest leaf area. Our results provide a rigorous theoretical underpinning for improving carbon cycle predictions through advancing model predictions of leaf area, and underscore that tree-level carbon allocation to leaves should be derived from first principles using mechanistic plant hydraulic processes in the next generation of vegetation models.
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Affiliation(s)
- Anna T Trugman
- School of Biological Sciences, University of Utah, Salt Lake City, Utah
- Department of Geography, University of California, Santa, Santa Barbara, California
| | - Leander D L Anderegg
- Department of Global Ecology, Carnegie Institution for Science, Stanford, California
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California
| | - Brett T Wolfe
- Smithsonian Tropical Research Institute, Balboa, Panama
| | - Benjamin Birami
- Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology (KIT), Garmisch-Partenkirchen, Germany
| | - Nadine K Ruehr
- Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology (KIT), Garmisch-Partenkirchen, Germany
| | - Matteo Detto
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey
| | - Megan K Bartlett
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey
- Department of Viticulture and Enology, University of California, Davis, California
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17
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Tariq A, Pan K, Olatunji OA, Graciano C, Li Z, Li N, Song D, Sun F, Wu X, Dakhil MA, Sun X, Zhang L. Impact of phosphorus application on drought resistant responses of Eucalyptus grandis seedlings. PHYSIOLOGIA PLANTARUM 2019; 166:894-908. [PMID: 30414178 DOI: 10.1111/ppl.12868] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 10/22/2018] [Accepted: 10/29/2018] [Indexed: 05/11/2023]
Abstract
Eucalyptus grandis is the most widely planted tree species worldwide and can face severe drought during the initial months after planting because the root system is developing. A complete randomized design was used to study the effects of two water regimes (well-watered and water-stressed) and phosphorus (P) applications (with and without P) on the morphological and physio-biochemical responses of E. grandis. Drought had negative effects on the growth and metabolism of E. grandis, as indicated by changes in morphological traits, decreased net photosynthetic rates (Pn ), pigment concentrations, leaf relative water contents (LRWCs), nitrogenous compounds, over-production of reactive oxygen species (ROS) and higher lipid peroxidation. However, E. grandis showed effective drought tolerance strategies, such as reduced leaf area and transpiration rate (E), higher accumulation of soluble sugars and proline and a strong antioxidative enzyme system. P fertilization had positive effects on well-watered seedlings due to improved growth and photosynthesis, which indicated the high P requirements during the initial E. grandis growth stage. In drought-stressed seedlings, P application had no effects on the morphological traits, but it significantly improved the LRWC, Pn , quantum efficiency of photosystem II (Fv /Fm ), chlorophyll pigments, nitrogenous compounds and reduced lipid peroxidation. P fertilization improved E. grandis seedling growth under well-watered conditions but also ameliorated some leaf physiological traits under drought conditions. The effects of P fertilization are mainly due to the enhancement of plant N nutrition. Therefore, P can be used as a fertilizer to improve growth and production in the face of future climate change.
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Affiliation(s)
- Akash Tariq
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization and Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
- International College, University of Chinese Academy of Sciences, Beijing, China
| | - Kaiwen Pan
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization and Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
| | - Olusanya A Olatunji
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization and Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
- International College, University of Chinese Academy of Sciences, Beijing, China
| | - Corina Graciano
- Instituto de Fisiología Vegetal, Consejo Nacional de Investigaciones Científicas y Técnicas - Universidad Nacional de La Plata, Buenos Aires, Argentina
| | - Zilong Li
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization and Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
- International College, University of Chinese Academy of Sciences, Beijing, China
| | - Ningning Li
- College of Resources and Environment, Southwest University, Chongqing, China
| | - Dagang Song
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization and Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
- International College, University of Chinese Academy of Sciences, Beijing, China
| | - Feng Sun
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization and Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
- International College, University of Chinese Academy of Sciences, Beijing, China
| | - Xiaogang Wu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization and Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
| | - Mohammed A Dakhil
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization and Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
- International College, University of Chinese Academy of Sciences, Beijing, China
- Botany and Microbiology department, Faculty of Science, Helwan University, Cairo, 11790, Egypt
| | - Xiaoming Sun
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization and Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
| | - Lin Zhang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization and Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, Sichuan, China
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18
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Zhu SD, Li RH, He PC, Siddiq Z, Cao KF, Ye Q. Large branch and leaf hydraulic safety margins in subtropical evergreen broadleaved forest. TREE PHYSIOLOGY 2019; 39:1405-1415. [PMID: 30901055 DOI: 10.1093/treephys/tpz028] [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: 09/09/2018] [Revised: 02/21/2019] [Accepted: 03/07/2019] [Indexed: 06/09/2023]
Abstract
As a global biodiversity hotspot, the subtropical evergreen broadleaved forest (SEBF) in southern China is strongly influenced by the humid monsoon climate, with distinct hot-wet and cool-dry seasons. However, the hydraulic strategies of this forest are not well understood. Branch and leaf hydraulic safety margins (HSMbranch and HSMleaf, respectively), as well as seasonal changes in predawn and midday leaf water potential (Ψpd and Ψmd), stomatal conductance (Gs), leaf to sapwood area ratio (AL/AS) and turgor loss point (Ψtlp), were examined for woody species in a mature SEBF. For comparison, we compiled these traits of tropical dry forests (TDFs) and Mediterranean-type woodlands (MWs) from the literature because they experience a hot-dry season. We found that on average, SEBF showed larger HSMbranch and HSMleaf than TDF and MW. During the dry season, TDF and MW species displayed a significant decrease in Ψpd and Ψmd. However, SEBF species showed a slight decrease in Ψpd but an increase in Ψmd. Similar to TDF and MW species, Gs was substantially lower in the dry season for SEBF species, but this might be primarily because of the low atmospheric temperature (low vapor pressure deficit). On the other hand, AL/AS and Ψtlp were not significant different between seasons for any SEBF species. Most SEBF species had leaves that were more resistant to cavitation than branches. Additionally, species with stronger leaf-to-branch vulnerability segmentation tended to have smaller HSMleaf but larger HSMbranch. Our results suggest that SEBF is at low hydraulic risk under the current climate.
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Affiliation(s)
- Shi-Dan Zhu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, Daxuedong Road, Xixiangtang District, Nanning, Guangxi, China
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Daxuedong Road, Xixiangtang District, Nanning, Guangxi, China
| | - Rong-Hua Li
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road, Tianhe District, Guangzhou, Guangdong, China
| | - Peng-Cheng He
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road, Tianhe District, Guangzhou, Guangdong, China
| | - Zafar Siddiq
- Department of Botany, Government College University, Katchery Road, Lahore, Pakistan
| | - Kun-Fang Cao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, Daxuedong Road, Xixiangtang District, Nanning, Guangxi, China
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Daxuedong Road, Xixiangtang District, Nanning, Guangxi, China
| | - Qing Ye
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road, Tianhe District, Guangzhou, Guangdong, China
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19
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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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20
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Effect of Long-Term vs. Short-Term Ambient Ozone Exposure on Radial Stem Growth, Sap Flux and Xylem Morphology of O3-Sensitive Poplar Trees. FORESTS 2019. [DOI: 10.3390/f10050396] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
High ozone (O3) pollution impairs the carbon and water balance of trees, which is of special interest in planted forests. However, the effect of long-term O3 exposure on tree growth and water use, little remains known. In this study, we analysed the relationships of intra-annual stem growth pattern, seasonal sap flow dynamics and xylem morphology to assess the effect of long term O3 exposure of mature O3-sensitive hybrid poplars (‘Oxford’ clone). Rooted cuttings were planted in autumn 2007 and drip irrigated with 2 liters of water as ambient O3 treatment, or 450 ppm ethylenediurea (N-[2-(2-oxo-1-imidazolidinyl)ethyl]-N0-phenylurea, abbreviated as EDU) solution as O3 protection treatment over all growing seasons. During 2013, point dendrometers and heat pulses were installed to monitor radial growth, stem water relations and sap flow. Ambient O3 did not affect growth rates, even if the seasonal culmination point was 20 days earlier on average than that recorded in the O3 protected trees. Under ambient O3, trees showed reduced seasonal sap flow, however, the lower water use was due to a decrease of Huber value (decrease of leaf area for sapwood unit) rather than to a change in xylem morphology or due to a direct effect of sluggish stomatal responses on transpiration. Under high evaporative demand and ambient O3 concentrations, trees showed a high use of internal stem water resources modulated by stomatal sluggishness, thus predisposing them to be more sensitive water deficit during summer. The results of this study help untangle the compensatory mechanisms involved in the acclimation processes of forest species to long-term O3 exposure in a context of global change.
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Lucani CJ, Brodribb TJ, Jordan G, Mitchell PJ. Intraspecific variation in drought susceptibility in Eucalyptus globulus is linked to differences in leaf vulnerability. FUNCTIONAL PLANT BIOLOGY : FPB 2019; 46:286-293. [PMID: 32172771 DOI: 10.1071/fp18077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 10/19/2018] [Indexed: 06/10/2023]
Abstract
Understanding intraspecific variation in the vulnerability of the xylem to hydraulic failure during drought is critical in predicting the response of forest tree species to climate change. However, few studies have assessed intraspecific variation in this trait, and a likely limitation is the large number of measurements required to generate the standard 'vulnerability curve' used to assess hydraulic failure. Here we explore an alternative approach that requires fewer measurements, and assess within species variation in leaf xylem vulnerability in Eucalyptus globulus Labill., an ecologically and economically important species with known genetic variation in drought tolerance. Using this approach we demonstrate significant phenotypic differences and evidence of plasticity among two provenances with contrasting drought tolerance.
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Affiliation(s)
- Christopher J Lucani
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tas. 7001, Australia
| | - Timothy J Brodribb
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tas. 7001, Australia
| | - Greg Jordan
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tas. 7001, Australia
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22
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Guérin M, Martin‐Benito D, von Arx G, Andreu‐Hayles L, Griffin KL, Hamdan R, McDowell NG, Muscarella R, Pockman W, Gentine P. Interannual variations in needle and sapwood traits of Pinus edulis branches under an experimental drought. Ecol Evol 2018; 8:1655-1672. [PMID: 29435241 PMCID: PMC5792598 DOI: 10.1002/ece3.3743] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Revised: 10/05/2017] [Accepted: 11/20/2017] [Indexed: 01/02/2023] Open
Abstract
In the southwestern USA, recent large-scale die-offs of conifers raise the question of their resilience and mortality under droughts. To date, little is known about the interannual structural response to droughts. We hypothesized that piñon pines (Pinus edulis) respond to drought by reducing the drop of leaf water potential in branches from year to year through needle morphological adjustments. We tested our hypothesis using a 7-year experiment in central New Mexico with three watering treatments (irrigated, normal, and rain exclusion). We analyzed how variation in "evaporative structure" (needle length, stomatal diameter, stomatal density, stomatal conductance) responded to watering treatment and interannual climate variability. We further analyzed annual functional adjustments by comparing yearly addition of needle area (LA) with yearly addition of sapwood area (SA) and distance to tip (d), defining the yearly ratios SA:LA and SA:LA/d. Needle length (l) increased with increasing winter and monsoon water supply, and showed more interannual variability when the soil was drier. Stomatal density increased with dryness, while stomatal diameter was reduced. As a result, anatomical maximal stomatal conductance was relatively invariant across treatments. SA:LA and SA:LA/d showed significant differences across treatments and contrary to our expectation were lower with reduced water input. Within average precipitation ranges, the response of these ratios to soil moisture was similar across treatments. However, when extreme soil drought was combined with high VPD, needle length, SA:LA and SA:LA/d became highly nonlinear, emphasizing the existence of a response threshold of combined high VPD and dry soil conditions. In new branch tissues, the response of annual functional ratios to water stress was immediate (same year) and does not attempt to reduce the drop of water potential. We suggest that unfavorable evaporative structural response to drought is compensated by dynamic stomatal control to maximize photosynthesis rates.
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Affiliation(s)
- Marceau Guérin
- Department of Earth and Environmental EngineeringColumbia UniversityNew YorkNYUSA
| | - Dario Martin‐Benito
- Forest EcologyDepartment of Environmental SciencesSwiss Federal Institute of TechnologyETH ZurichZürichSwitzerland
- Forest Research Center (INIA‐CIFOR)MadridSpain
- Tree‐ring LaboratoryLamont‐Doherty Earth Observatory of Columbia UniversityPalisadesNYUSA
| | - Georg von Arx
- Swiss Federal Institute for Forest, Snow and Landscape Research WSLBirmensdorfSwitzerland
- Climatic Change and Climate ImpactsInstitute for Environmental SciencesGenevaSwitzerland
| | - Laia Andreu‐Hayles
- Tree‐ring LaboratoryLamont‐Doherty Earth Observatory of Columbia UniversityPalisadesNYUSA
| | - Kevin L. Griffin
- Department of Earth and Environmental SciencesLamont‐Doherty Earth Observatory of Columbia UniversityPalisadesNYUSA
| | | | - Nate G. McDowell
- Atmospheric Sciences and Global Change DivisionPacific Northwest National LaboratoryRichlandWAUSA
| | - Robert Muscarella
- Ecoinformatics & BiodiversityDepartment of BioscienceAarhus UniversityAarhusDenmark
| | - William Pockman
- Department of BiologyUniversity of New MexicoAlbuquerqueNMUSA
| | - Pierre Gentine
- Department of Earth and Environmental EngineeringEarth InstituteColumbia UniversityNew YorkNYUSA
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23
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Zhu SD, Chen YJ, Fu PL, Cao KF. Different hydraulic traits of woody plants from tropical forests with contrasting soil water availability. TREE PHYSIOLOGY 2017; 37:1469-1477. [PMID: 28985366 DOI: 10.1093/treephys/tpx094] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 06/22/2017] [Indexed: 05/18/2023]
Abstract
In southwestern China, tropical karst forests (KF) and non-karst rain forests (NKF) have different species composition and forest structure owing to contrasting soil water availability, but with a few species that occur in both forests. Plant hydraulic traits are important for understanding the species' distribution patterns in these two forest types, but related studies are rare. In this study, we investigated hydraulic conductivity, vulnerability to drought-induced cavitation and wood anatomy of 23 abundant and typical woody species from a KF and a neighboring NKF, as well as two Bauhinia liana species common to both forests. We found that the KF species tended to have higher sapwood density, smaller vessel diameter, lower specific hydraulic conductivity (ks) and leaf to sapwood area ratio, and were more resistant to cavitation than NKF species. Across the 23 species distinctly occurring in either KF or NKF, there was a significant tradeoff between hydraulic efficiency and safety, which might be an underlying mechanism for distributions of these species across the two forests. Interestingly, by possessing rather large and long vessels, the two Bauhinia liana species had extremely high ks but were also high resistance to cavitation (escaping hydraulic tradeoff). This might be partially due to their distinctly dimorphic vessels, but contribute to their wide occurrence in both forests.
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Affiliation(s)
- Shi-Dan Zhu
- Guangxi Key Laboratory of Forest Ecology and Conservation, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Forestry, Guangxi University, Nanning 530004, Guangxi, China
| | - Ya-Jun Chen
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, Yunnan, China
| | - Pei-Li Fu
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, Yunnan, China
| | - Kun-Fang Cao
- Guangxi Key Laboratory of Forest Ecology and Conservation, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Forestry, Guangxi University, Nanning 530004, Guangxi, China
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24
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Bazihizina N, Veneklaas EJ, Barrett-Lennard EG, Colmer TD. Hydraulic redistribution: limitations for plants in saline soils. PLANT, CELL & ENVIRONMENT 2017; 40:2437-2446. [PMID: 28707352 DOI: 10.1111/pce.13020] [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: 01/10/2017] [Accepted: 06/25/2017] [Indexed: 06/07/2023]
Abstract
Hydraulic redistribution (HR), the movement of water from wet to dry patches in the soil via roots, occurs in different ecosystems and plant species. By extension of the principle that HR is driven by gradients in soil water potential, HR has been proposed to occur for plants in saline soils. Despite the inherent spatial patchiness and salinity gradients in these soils, the lack of direct evidence of HR in response to osmotic gradients prompted us to ask the question: are there physical or physiological constraints to HR for plants in saline environments? We propose that build-up of ions in the root xylem sap and in the leaf apoplast, with the latter resulting in a large predawn disequilibrium of water potential in shoots compared with roots and soil, would both impede HR. We present a conceptual model that illustrates how processes in root systems in heterogeneous salinity with water potential gradients, even if equal to those in non-saline soils, will experience a dampened magnitude of water potential gradients in the soil-plant continuum, minimizing or preventing HR. Finally, we provide an outlook for understanding the relevance of HR for plants in saline environments by addressing key research questions on plant salinity tolerance.
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Affiliation(s)
- Nadia Bazihizina
- Department of Agrifood Production and Environmental Sciences, Università degli Studi di Firenze, Viale delle Idee 30, 50019 Sesto Fiorentino, Florence, Italy
- School of Land and Food, University of Tasmania, Hobart, TAS, 7001, Australia
- UWA School of Agriculture and Environment, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Erik J Veneklaas
- UWA School of Agriculture and Environment, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
- School of Biological Sciences, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
- The UWA Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Edward G Barrett-Lennard
- UWA School of Agriculture and Environment, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
- Department of Agriculture and Food, Western Australia, 3 Baron-Hay Court, South, Perth, Western Australia, 6151, Australia
- School of Veterinary and Life Science, Murdoch University, 90 South Street, Murdoch, Western Australia, 6150, Australia
| | - Timothy D Colmer
- UWA School of Agriculture and Environment, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
- The UWA Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
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25
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Zolfaghar S, Villalobos-Vega R, Zeppel M, Cleverly J, Rumman R, Hingee M, Boulain N, Li Z, Eamus D. Transpiration of Eucalyptus woodlands across a natural gradient of depth-to-groundwater. TREE PHYSIOLOGY 2017; 37:961-975. [PMID: 28369559 DOI: 10.1093/treephys/tpx024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 02/24/2017] [Indexed: 05/22/2023]
Abstract
Water resources and their management present social, economic and environmental challenges, with demand for human consumptive, industrial and environmental uses increasing globally. However, environmental water requirements, that is, the allocation of water to the maintenance of ecosystem health, are often neglected or poorly quantified. Further, transpiration by trees is commonly a major determinant of the hydrological balance of woodlands but recognition of the role of groundwater in hydrological balances of woodlands remains inadequate, particularly in mesic climates. In this study, we measured rates of tree water-use and sapwood 13C isotopic ratio in a mesic, temperate Eucalypt woodland along a naturally occurring gradient of depth-to-groundwater (DGW), to examine daily, seasonal and annual patterns of transpiration. We found that: (i) the maximum rate of stand transpiration was observed at the second shallowest site (4.3 m) rather than the shallowest (2.4 m); (ii) as DGW increased from 4.3 to 37.5 m, stand transpiration declined; (iii) the smallest rate of stand transpiration was observed at the deepest (37.5 m) site; (iv) intrinsic water-use efficiency was smallest at the two intermediate DGW sites as reflected in the Δ13C of the most recently formed sapwood and largest at the deepest and shallowest DGW sites, reflecting the imposition of flooding at the shallowest site and the inaccessibility of groundwater at the deepest site; and (v) there was no evidence of convergence in rates of water-use for co-occurring species at any site. We conclude that even in mesic environments groundwater can be utilized by trees. We further conclude that these forests are facultatively groundwater-dependent when groundwater depth is <9 m and suggest that during drier-than-average years the contribution of groundwater to stand transpiration is likely to increase significantly at the three shallowest DGW sites.
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Affiliation(s)
- Sepideh Zolfaghar
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
- National Centre for Groundwater Research and Training, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
| | - Randol Villalobos-Vega
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
- National Centre for Groundwater Research and Training, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
| | - Melanie Zeppel
- Department of Biological Sciences, Macquarie University, Balaclava Road, North Ryde, NSW 2107, Australia
| | - James Cleverly
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW2007, Australia
| | - Rizwana Rumman
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
- National Centre for Groundwater Research and Training, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
| | - Matthew Hingee
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW2007, Australia
| | - Nicolas Boulain
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW2007, Australia
| | - Zheng Li
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW2007, Australia
| | - Derek Eamus
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
- National Centre for Groundwater Research and Training, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
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26
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Evaristo J, McDonnell JJ. Prevalence and magnitude of groundwater use by vegetation: a global stable isotope meta-analysis. Sci Rep 2017; 7:44110. [PMID: 28281644 PMCID: PMC5345103 DOI: 10.1038/srep44110] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 02/02/2017] [Indexed: 11/09/2022] Open
Abstract
The role of groundwater as a resource in sustaining terrestrial vegetation is widely recognized. But the global prevalence and magnitude of groundwater use by vegetation is unknown. Here we perform a meta-analysis of plant xylem water stable isotope (δ2H and δ18O, n = 7367) information from 138 published papers - representing 251 genera, and 414 species of angiosperms (n = 376) and gymnosperms (n = 38). We show that the prevalence of groundwater use by vegetation (defined as the number of samples out of a universe of plant samples reported to have groundwater contribution to xylem water) is 37% (95% confidence interval, 28-46%). This is across 162 sites and 12 terrestrial biomes (89% of heterogeneity explained; Q-value = 1235; P < 0.0001). However, the magnitude of groundwater source contribution to the xylem water mixture (defined as the proportion of groundwater contribution in xylem water) is limited to 23% (95% CI, 20-26%; 95% prediction interval, 3-77%). Spatial analysis shows that the magnitude of groundwater source contribution increases with aridity. Our results suggest that while groundwater influence is globally prevalent, its proportional contribution to the total terrestrial transpiration is limited.
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Affiliation(s)
- Jaivime Evaristo
- Global Institute for Water Security and School of Environment and Sustainability, University of Saskatchewan, Saskatoon, Canada
| | - Jeffrey J. McDonnell
- Global Institute for Water Security and School of Environment and Sustainability, University of Saskatchewan, Saskatoon, Canada
- School of Geosciences, University of Aberdeen, Aberdeen, Scotland, United Kingdom
- Department of Forest Engineering, Resources and Management, Oregon State University, Corvallis, Oregon 97330 USA
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27
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Glanville K, Ryan T, Tomlinson M, Muriuki G, Ronan M, Pollett A. A Method for Catchment Scale Mapping of Groundwater-Dependent Ecosystems to Support Natural Resource Management (Queensland, Australia). ENVIRONMENTAL MANAGEMENT 2016; 57:432-449. [PMID: 26404433 DOI: 10.1007/s00267-015-0612-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 09/10/2015] [Indexed: 06/05/2023]
Abstract
Immediate and foreseeable threats to groundwater-dependent ecosystems (GDEs) are widely acknowledged, many linked to altered groundwater regimes including changes in groundwater flow, flux, pressure, level and/or quality (Eamus et al. in Aust J Bot 54:97-114, 2006a). Natural resource managers and other decision-makers often lack sufficient information at an appropriate scale to understand the groundwater dependency of ecosystems and ensure that GDEs are adequately considered in decision-making processes. This paper describes a new catchment scale mapping method for GDEs based on the integration of local expert knowledge with detailed spatial datasets to delineate GDEs at a scale compatible with management and planning activities. This overcomes one of the key criticisms often levelled at broader scale mapping methods-that information from local and regional experts, with significant understanding of landscape processes and ecosystems, is not incorporated into the datasets used by decision-makers. Expert knowledge is conveyed in the form of pictorial conceptual models representing the components, processes and interrelationships of groundwater within a catchment and the ecosystems dependent on it. Each mapped GDE is linked to a pictorial conceptual model and a mapping rule-set to provide decision-makers with valuable information about where, how and why GDEs exist in a landscape.
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Affiliation(s)
- K Glanville
- Department of Natural Resources and Mines, Queensland Government, 400 George Street, Brisbane, QLD, 4000, Australia.
- Department of Science, Information Technology, and Innovation, Queensland Government, Queensland Herbarium, Mount Coot-tha Road, Toowong, QLD, 4066, Australia.
| | - T Ryan
- Department of Science, Information Technology, and Innovation, Queensland Government, Queensland Herbarium, Mount Coot-tha Road, Toowong, QLD, 4066, Australia
| | - M Tomlinson
- Department of Natural Resources and Mines, Queensland Government, 400 George Street, Brisbane, QLD, 4000, Australia
- Department of the Environment, Australian Government, John Gorton Building, King Edward Terrace, Parkes, ACT, 2600, Australia
| | - G Muriuki
- Department of Science, Information Technology, and Innovation, Queensland Government, Queensland Herbarium, Mount Coot-tha Road, Toowong, QLD, 4066, Australia
- The University of Queensland, St Lucia, QLD, 4072, Australia
| | - M Ronan
- Department of Environment and Heritage Protection, Queensland Government, 400 George Street, Brisbane, QLD, 4000, Australia
| | - A Pollett
- Department of Natural Resources and Mines, Queensland Government, 52-64 Currie Street, Nambour, QLD, 4560, Australia
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Zolfaghar S, Villalobos-Vega R, Zeppel M, Eamus D. The hydraulic architecture of Eucalyptus trees growing across a gradient of depth-to-groundwater. FUNCTIONAL PLANT BIOLOGY : FPB 2015; 42:888-898. [PMID: 32480731 DOI: 10.1071/fp14324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 06/09/2015] [Indexed: 06/11/2023]
Abstract
Heterogeneity in water availability acts as an important driver of variation in plant structure and function. Changes in hydraulic architecture represent a key mechanism by which adaptation to changes in water availability can be expressed in plants. The aim of this study was to investigate whether differences in depth-to-groundwater influence the hydraulic architecture of Eucalyptus trees in remnant woodlands within mesic environments. Hydraulic architecture of trees was examined in winter and summer by measuring the following traits: Huber value (HV: the ratio between sapwood area and leaf area), branch hydraulic conductivity (leaf and sapwood area specific), sapwood density, xylem vulnerability (P50 and Pe) and hydraulic safety margins across four sites where depth-to-groundwater ranged from 2.4 to 37.5m. Huber value increased significantly as depth-to-groundwater increased. Neither sapwood density nor branch hydraulic conductivity (sapwood and leaf area specific) varied significantly across sites. Xylem vulnerability to embolism (represented by P50 and Pe) in both seasons was significantly and negatively correlated with depth-to-groundwater. Hydraulic safety margins increased with increasing depth-to-groundwater and therefore trees growing at sites with deeper water tables were less sensitive to drought induced embolism. These results showed plasticity in some, but not all, hydraulic traits (as reflected in HV, P50, Pe and hydraulic safety margin) in response to increase in depth-to-groundwater in a mesic environment.
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Affiliation(s)
- Sepideh Zolfaghar
- University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
| | | | - Melanie Zeppel
- Department of Biological Sciences, Macquarie University, Balaclava Road, North Ryde, NSW 2109, Australia
| | - Derek Eamus
- University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
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Zolfaghar S, Villalobos-Vega R, Cleverly J, Eamus D. Co-ordination among leaf water relations and xylem vulnerability to embolism of Eucalyptus trees growing along a depth-to-groundwater gradient. TREE PHYSIOLOGY 2015; 35:732-743. [PMID: 26023059 DOI: 10.1093/treephys/tpv039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 04/19/2015] [Indexed: 06/04/2023]
Abstract
The importance of groundwater resources in arid and semi-arid areas for plant survival is well documented. However, there have been few studies examining the importance and impacts of groundwater availability in mesic environments. The aim of this study was to determine how depth-to-groundwater (DGW) impacts on leaf water relations, leaf structure and branch xylem vulnerability to embolism in a mesic environment. We hypothesize that increasing DGW results in increased resistance to drought stress and that this will be manifested across leaf and branch attributes pertaining to water relations. We further investigate whether there is co-ordination across leaf and branch-scale level responses to increased DGW. Four species were used in this study: Eucalyptus globoidea Blakely, E. piperita Sm., E. sclerophylla (Blakely) L.A.S.Johnson & Blaxell and E. sieberi L.A.S.Johnson. Six sites were chosen along an 11 km transect to span a range of average DGW: 2.4, 4.3, 9.8, 13, 16.3 and 37.5 m. Leaf water relations of trees showed less sensitivity to drought stress as DGW increased. This was reflected in significantly lower leaf turgor loss point and maximum osmotic potential, increased maximum turgor and a reduced leaf relative water content as DGW increased. At shallow DGW sites, minimum diurnal leaf water potentials were generally more negative than leaf water potential at zero turgor, but the reverse was observed at deep sites, indicating a larger growth potential safety margin at deep sites compared with shallow sites. Leaf cell wall elasticity varied independently of DGW. Xylem vulnerability to embolism was quantified as the water potential associated with 50% loss of conductance (P 50). In both summer and winter P 50 was significantly and negatively correlated with DGW. Co-ordination between leaf- and branch-level responses to increase in DGW was apparent, which strongly supports the conclusion that groundwater supply influenced woodland structure and functional behaviour.
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Affiliation(s)
- Sepideh Zolfaghar
- University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia National Centre for Groundwater Research and Training, University of Technology Sydney, PO BOX 123, Broadway, NSW, 2007, Australia
| | - Randol Villalobos-Vega
- University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia National Centre for Groundwater Research and Training, University of Technology Sydney, PO BOX 123, Broadway, NSW, 2007, Australia
| | - James Cleverly
- University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia National Centre for Groundwater Research and Training, University of Technology Sydney, PO BOX 123, Broadway, NSW, 2007, Australia
| | - Derek Eamus
- University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia National Centre for Groundwater Research and Training, University of Technology Sydney, PO BOX 123, Broadway, NSW, 2007, Australia
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30
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Le Maitre DC, Gush MB, Dzikiti S. Impacts of invading alien plant species on water flows at stand and catchment scales. AOB PLANTS 2015; 7:plv043. [PMID: 25935861 PMCID: PMC4480063 DOI: 10.1093/aobpla/plv043] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 03/26/2015] [Indexed: 06/04/2023]
Abstract
There have been many studies of the diverse impacts of invasions by alien plants but few have assessed impacts on water resources. We reviewed the information on the impacts of invasions on surface runoff and groundwater resources at stand to catchment scales and covering a full annual cycle. Most of the research is South African so the emphasis is on South Africa's major invaders with data from commercial forest plantations where relevant. Catchment studies worldwide have shown that changes in vegetation structure and the physiology of the dominant plant species result in changes in surface runoff and groundwater discharge, whether they involve native or alien plant species. Where there is little change in vegetation structure [e.g. leaf area (index), height, rooting depth and seasonality] the effects of invasions generally are small or undetectable. In South Africa, the most important woody invaders typically are taller and deeper rooted than the native species. The impacts of changes in evaporation (and thus runoff) in dryland settings are constrained by water availability to the plants and, thus, by rainfall. Where the dryland invaders are evergreen and the native vegetation (grass) is seasonal, the increases can reach 300-400 mm/year. Where the native vegetation is evergreen (shrublands) the increases are ∼200-300 mm/year. Where water availability is greater (riparian settings or shallow water tables), invading tree water-use can reach 1.5-2.0 times that of the same species in a dryland setting. So, riparian invasions have a much greater impact per unit area invaded than dryland invasions. The available data are scattered and incomplete, and there are many gaps and issues that must be addressed before a thorough understanding of the impacts at the site scale can be gained and used in extrapolating to watershed scales, and in converting changes in flows to water supply system yields.
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Affiliation(s)
- D C Le Maitre
- CSIR Natural Resources and the Environment, PO Box 320, Stellenbosch 7599, South Africa Centre for Invasion Biology, Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
| | - M B Gush
- CSIR Natural Resources and the Environment, PO Box 320, Stellenbosch 7599, South Africa
| | - S Dzikiti
- CSIR Natural Resources and the Environment, PO Box 320, Stellenbosch 7599, South Africa
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Christina M, Le Maire G, Battie-Laclau P, Nouvellon Y, Bouillet JP, Jourdan C, de Moraes Gonçalves JL, Laclau JP. Measured and modeled interactive effects of potassium deficiency and water deficit on gross primary productivity and light-use efficiency in Eucalyptus grandis plantations. GLOBAL CHANGE BIOLOGY 2015; 21:2022-39. [PMID: 25430918 DOI: 10.1111/gcb.12817] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 10/06/2014] [Indexed: 05/16/2023]
Abstract
Global climate change is expected to increase the length of drought periods in many tropical regions. Although large amounts of potassium (K) are applied in tropical crops and planted forests, little is known about the interaction between K nutrition and water deficit on the physiological mechanisms governing plant growth. A process-based model (MAESPA) parameterized in a split-plot experiment in Brazil was used to gain insight into the combined effects of K deficiency and water deficit on absorbed radiation (aPAR), gross primary productivity (GPP), and light-use efficiency for carbon assimilation and stem biomass production (LUEC and LUEs ) in Eucalyptus grandis plantations. The main-plot factor was the water supply (undisturbed rainfall vs. 37% of throughfall excluded) and the subplot factor was the K supply (with or without 0.45 mol K m(-2 ) K addition). Mean GPP was 28% lower without K addition over the first 3 years after planting whether throughfall was partly excluded or not. K deficiency reduced aPAR by 20% and LUEC by 10% over the whole period of growth. With K addition, throughfall exclusion decreased GPP by 25%, resulting from a 21% decrease in LUEC at the end of the study period. The effect of the combination of K deficiency and water deficit was less severe than the sum of the effects of K deficiency and water deficit individually, leading to a reduction in stem biomass production, gross primary productivity and LUE similar to K deficiency on its own. The modeling approach showed that K nutrition and water deficit influenced absorbed radiation essentially through changes in leaf area index and tree height. The changes in gross primary productivity and light-use efficiency were, however, driven by a more complex set of tree parameters, especially those controlling water uptake by roots and leaf photosynthetic capacities.
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Affiliation(s)
- Mathias Christina
- UMR Eco&Sols, CIRAD, 2 place Viala, 34060, Montpellier, France; SupAgro Montpellier, 2 place Viala, 34060, Montpellier, France
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Martin-Stpaul NK, Limousin JM, Vogt-Schilb H, Rodríguez-Calcerrada J, Rambal S, Longepierre D, Misson L. The temporal response to drought in a Mediterranean evergreen tree: comparing a regional precipitation gradient and a throughfall exclusion experiment. GLOBAL CHANGE BIOLOGY 2013; 19:2413-26. [PMID: 23553916 DOI: 10.1111/gcb.12215] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 03/01/2013] [Accepted: 03/12/2013] [Indexed: 05/25/2023]
Abstract
Like many midlatitude ecosystems, Mediterranean forests will suffer longer and more intense droughts with the ongoing climate change. The responses to drought in long-lived trees differ depending on the time scale considered, and short-term responses are currently better understood than longer term acclimation. We assessed the temporal changes in trees facing a chronic reduction in water availability by comparing leaf-scale physiological traits, branch-scale hydraulic traits, and stand-scale biomass partitioning in the evergreen Quercus ilex across a regional precipitation gradient (long-term changes) and in a partial throughfall exclusion experiment (TEE, medium term changes). At the leaf scale, gas exchange, mass per unit area and nitrogen concentration showed homeostatic responses to drought as they did not change among the sites of the precipitation gradient or in the experimental treatments of the TEE. A similar homeostatic response was observed for the xylem vulnerability to cavitation at the branch scale. In contrast, the ratio of leaf area over sapwood area (LA/SA) in young branches exhibited a transient response to drought because it decreased in response to the TEE the first 4 years of treatment, but did not change among the sites of the gradient. At the stand scale, leaf area index (LAI) decreased, and the ratios of stem SA to LAI and of fine root area to LAI both increased in trees subjected to throughfall exclusion and from the wettest to the driest site of the gradient. Taken together, these results suggest that acclimation to chronic drought in long-lived Q. ilex is mediated by changes in hydraulic allometry that shift progressively from low (branch) to high (stand) organizational levels, and act to maintain the leaf water potential within the range of xylem hydraulic function and leaf photosynthetic assimilation.
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Caplan JS, Yeakley JA. Functional morphology underlies performance differences among invasive and non-invasive ruderal Rubus species. Oecologia 2013; 173:363-74. [DOI: 10.1007/s00442-013-2639-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 02/28/2013] [Indexed: 10/26/2022]
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Abstract
Shallow groundwater affects terrestrial ecosystems by sustaining river base-flow and root-zone soil water in the absence of rain, but little is known about the global patterns of water table depth and where it provides vital support for land ecosystems. We present global observations of water table depth compiled from government archives and literature, and fill in data gaps and infer patterns and processes using a groundwater model forced by modern climate, terrain, and sea level. Patterns in water table depth explain patterns in wetlands at the global scale and vegetation gradients at regional and local scales. Overall, shallow groundwater influences 22 to 32% of global land area, including ~15% as groundwater-fed surface water features and 7 to 17% with the water table or its capillary fringe within plant rooting depths.
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Affiliation(s)
- Y Fan
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08854, USA.
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Lewis JD, Phillips NG, Logan BA, Hricko CR, Tissue DT. Leaf photosynthesis, respiration and stomatal conductance in six Eucalyptus species native to mesic and xeric environments growing in a common garden. TREE PHYSIOLOGY 2011; 31:997-1006. [PMID: 21937672 DOI: 10.1093/treephys/tpr087] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Trees adapted to mesic and xeric habits may differ in a suite of physiological responses that affect leaf-level carbon balance, including the relationship between photosynthesis (A) and respiration at night (R(n)). Understanding the factors that regulate physiological function in mesic and xeric species is critical for predicting changes in growth and distribution under changing climates. In this study, we examined the relationship between A and R(n), and leaf traits that may regulate A and R(n), in six Eucalyptus species native to mesic or xeric ecosystems, during two 24-h cycles in a common garden under high soil moisture. Peak A and R(n) generally were higher in xeric compared with mesic species. Across species, A and R(n) covaried, correlated with leaf mass per area, leaf N per unit area and daytime soluble sugar accumulation. A also covaried with g(s), which accounted for 93% of the variation in A within species. These results suggest that A and R(n) in these six Eucalyptus species were linked through leaf N and carbohydrates. Further, the relationship between A and R(n) across species suggests that differences in this relationship between mesic and xeric Eucalyptus species in their native habitats may be largely driven by environmental factors rather than inter-specific genetic variation.
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Affiliation(s)
- James D Lewis
- Hawkesbury Institute for Environment, University of Western Sydney, Richmond, NSW 2753, Australia.
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