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Castillo-Argaez R, Sapes G, Mallen N, Lippert A, John GP, Zare A, Hammond WM. Spectral ecophysiology: hyperspectral pressure-volume curves to estimate leaf turgor loss. THE NEW PHYTOLOGIST 2024; 242:935-946. [PMID: 38482720 DOI: 10.1111/nph.19669] [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: 11/28/2023] [Accepted: 02/19/2024] [Indexed: 04/12/2024]
Abstract
Turgor loss point (TLP) is an important proxy for plant drought tolerance, species habitat suitability, and drought-induced plant mortality risk. Thus, TLP serves as a critical tool for evaluating climate change impacts on plants, making it imperative to develop high-throughput and in situ methods to measure TLP. We developed hyperspectral pressure-volume curves (PV curves) to estimate TLP using leaf spectral reflectance. We used partial least square regression models to estimate water potential (Ψ) and relative water content (RWC) for two species, Frangula caroliniana and Magnolia grandiflora. RWC and Ψ's model for each species had R2 ≥ 0.7 and %RMSE = 7-10. We constructed PV curves with model estimates and compared the accuracy of directly measured and spectra-predicted TLP. Our findings indicate that leaf spectral measurements are an alternative method for estimating TLP. F. caroliniana TLP's values were -1.62 ± 0.15 (means ± SD) and -1.62 ± 0.34 MPa for observed and reflectance predicted, respectively (P > 0.05), while M. grandiflora were -1.78 ± 0.34 and -1.66 ± 0.41 MPa (P > 0.05). The estimation of TLP through leaf reflectance-based PV curves opens a broad range of possibilities for future research aimed at understanding and monitoring plant water relations on a large scale with spectral ecophysiology.
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Affiliation(s)
| | - Gerard Sapes
- Agronomy Department, University of Florida, Gainesville, FL, 32611, USA
| | - Nicole Mallen
- Agronomy Department, University of Florida, Gainesville, FL, 32611, USA
| | - Alston Lippert
- Agronomy Department, University of Florida, Gainesville, FL, 32611, USA
| | - Grace P John
- Department of Biology, University of Florida, Gainesville, FL, 32611, USA
| | - Alina Zare
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - William M Hammond
- Agronomy Department, University of Florida, Gainesville, FL, 32611, USA
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2
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Zhang X, Ma S, Hu H, Li F, Bao W, Huang L. A trade-off between leaf hydraulic efficiency and safety across three xerophytic species in response to increased rock fragment content. TREE PHYSIOLOGY 2024; 44:tpae010. [PMID: 38245807 PMCID: PMC10918055 DOI: 10.1093/treephys/tpae010] [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: 08/11/2023] [Revised: 01/05/2024] [Accepted: 01/14/2024] [Indexed: 01/22/2024]
Abstract
Limited information is available on the variation of plant leaf hydraulic traits in relation to soil rock fragment content (RFC), particularly for xerophytes native to rocky mountain areas. In this study, we conducted a field experiment with four gradients of RFC (0, 25, 50 and 75% ν ν-1) on three different xerophytic species (Sophora davidii, Cotinus szechuanensis and Bauhinia brachycarpa). We measured predawn and midday leaf water potential (Ψleaf), leaf hydraulic conductance (Kleaf), Ψleaf induced 50% loss of Kleaf (P50), pressure-volume curve traits and leaf structure. A consistent response of hydraulic traits to increased RFC was observed in three species. Kleaf showed a decrease, whereas P50 and turgor loss point (Ψtlp) became increasingly negative with increasing RFC. Thus, a clear trade-off between hydraulic efficiency and safety was observed in the xerophytic species. In all three species, the reduction in Kleaf was associated with an increase in leaf mass per area. In S. davidii, alterations in Kleaf and P50 were driven by leaf vein density (VLA) and Ψtlp. In C. szechuanensis, Ψtlp and VLA drove the changes in Kleaf and P50, respectively. In B. brachycarpa, changes in P50 were driven by VLA, whereas changes in both Kleaf and P50 were simultaneously influenced by Ψtlp. Our findings suggest that adaptation to increased rockiness necessarily implies a trade-off between leaf hydraulic efficiency and safety in xerophytic species. Additionally, the trade-off between leaf hydraulic efficiency and safety among xerophytic species is likely to result from processes occurring in the xylem and the outside-xylem hydraulic pathways. These findings contribute to a better understanding of the survival strategies and mechanisms of xerophytes in rocky soils, and provide a theoretical basis for the persistence of xerophytic species in areas with stony substrates.
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Affiliation(s)
- Xiulong Zhang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4 South Renmin Road, Wuhou District, Chengdu, Sichuan 610041, China
| | - Shaowei Ma
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4 South Renmin Road, Wuhou District, Chengdu, Sichuan 610041, China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Hui Hu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4 South Renmin Road, Wuhou District, Chengdu, Sichuan 610041, China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Fanglan Li
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4 South Renmin Road, Wuhou District, Chengdu, Sichuan 610041, China
| | - Weikai Bao
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4 South Renmin Road, Wuhou District, Chengdu, Sichuan 610041, China
| | - Long Huang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4 South Renmin Road, Wuhou District, Chengdu, Sichuan 610041, China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Shijingshan District, Beijing 100049, China
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3
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Blackman CJ, Billon LM, Cartailler J, Torres-Ruiz JM, Cochard H. Key hydraulic traits control the dynamics of plant dehydration in four contrasting tree species during drought. TREE PHYSIOLOGY 2023; 43:1772-1783. [PMID: 37318310 PMCID: PMC10652334 DOI: 10.1093/treephys/tpad075] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/07/2023] [Accepted: 06/08/2023] [Indexed: 06/16/2023]
Abstract
Trees are at risk of mortality during extreme drought, yet our understanding of the traits that govern the timing of drought-induced hydraulic failure remains limited. To address this, we tested SurEau, a trait-based soil-plant-atmosphere model designed to predict the dynamics of plant dehydration as represented by the changes in water potential against those observed in potted trees of four contrasting species (Pinus halepensis Mill., Populus nigra L., Quercus ilex L. and Cedrus atlantica (Endl.) Manetti ex Carriére) exposed to drought. SurEau was parameterized with a range of plant hydraulic and allometric traits, soil and climatic variables. We found a close correspondence between the predicted and observed plant water potential (in MPa) dynamics during the early phase drought, leading to stomatal closure, as well as during the latter phase of drought, leading to hydraulic failure in all four species. A global model's sensitivity analysis revealed that, for a common plant size (leaf area) and soil volume, dehydration time from full hydration to stomatal closure (Tclose) was most strongly controlled by the leaf osmotic potential (Pi0) and its influence on stomatal closure, in all four species, while the maximum stomatal conductance (gsmax) also contributed to Tclose in Q. ilex and C. atlantica. Dehydration times from stomatal closure to hydraulic failure (Tcav) was most strongly controlled by Pi0, the branch residual conductance (gres) and Q10a sensitivity of gres in the three evergreen species, while xylem embolism resistance (P50) was most influential in the deciduous species P. nigra. Our findings point to SurEau as a highly useful model for predicting changes in plant water status during drought and suggest that adjustments made in key hydraulic traits are potentially beneficial to delaying the onset of drought-induced hydraulic failure in trees.
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Affiliation(s)
- Chris J Blackman
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, School of Natural Sciences, University of Tasmania, Hobart 7001, Australia
- Université Clermont-Auvergne, INRAE, PIAF, Clermont-Ferrand 63100, France
| | - Lise-Marie Billon
- Université Clermont-Auvergne, INRAE, PIAF, Clermont-Ferrand 63100, France
| | - Julien Cartailler
- Université Clermont-Auvergne, INRAE, PIAF, Clermont-Ferrand 63100, France
| | - José M Torres-Ruiz
- Université Clermont-Auvergne, INRAE, PIAF, Clermont-Ferrand 63100, France
| | - Hervé Cochard
- Université Clermont-Auvergne, INRAE, PIAF, Clermont-Ferrand 63100, France
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Zhang Y, Zhao J, Xu J, Chai Y, Liu P, Quan J, Wu X, Li C, Yue M. Effects of Water Availability on the Relationships Between Hydraulic and Economic Traits in the Quercus wutaishanica Forests. FRONTIERS IN PLANT SCIENCE 2022; 13:902509. [PMID: 35720582 PMCID: PMC9199496 DOI: 10.3389/fpls.2022.902509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 05/03/2022] [Indexed: 05/02/2023]
Abstract
Water availability is a key environmental factor affecting plant species distribution, and the relationships between hydraulic and economic traits are important for understanding the species' distribution patterns. However, in the same community type but within different soil water availabilities, the relationships in congeneric species remain ambiguous. In northwest China, Quercus wutaishanica forests in the Qinling Mountains (QM, humid region) and Loess Plateau (LP, drought region) have different species composition owing to contrasting soil water availability, but with common species occurring in two regions. We analyzed eight hydraulic traits [stomatal density (SD), vein density (VD), wood specific gravity (WSGbranch), lower leaf area: sapwood area (Al: As), stomatal length (SL), turgor loss point (ΨTlp), maximum vessel diameter (Vdmax) and height (Height)] and five economic traits [leaf dry matter content (LDMC), leaf tissue density (TD), leaf dry mass per area (LMA), Leaf thickness (LT) and maximum net photosynthetic rate (Pmax)] of congeneric species (including common species and endemic species) in Q. wutaishanica forests of QM and LP. We explored whether the congeneric species have different economic and hydraulic traits across regions. And whether the relationship between hydraulic and economic traits was determined by soil water availability, and whether it was related to species distribution and congeneric endemic species composition of the same community. We found that LP species tended to have higher SD, VD, WSGbranch, Al: As, SL, ΨTlp and Vdmax than QM species. There was a significant trade-off between hydraulic efficiency and safety across congeneric species. Also, the relationships between hydraulic and economic traits were closer in LP than in QM. These results suggested that relationships between hydraulic and economic traits, hydraulic efficiency and safety played the role in constraining species distribution across regions. Interestingly, some relationships between traits changed (from significant correlation to non-correlation) in common species across two regions (from LP to QM), but not in endemic species. The change of these seven pairs of relationships might be a reason for common species' wide occurrence in the two Q. wutaishanica forests with different soil water availability. In drought or humid conditions, congeneric species developed different types of adaptation mechanisms. The study helps to understand the environmental adaptive strategies of plant species, and the results improve our understanding of the role of both hydraulic and economic traits during community assembly.
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Affiliation(s)
- Yuhan Zhang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Xi'an, China
| | - Jiale Zhao
- Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Xi'an, China
| | - Jinshi Xu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Xi'an, China
| | - Yongfu Chai
- Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Xi'an, China
| | - Peiliang Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Xi'an, China
| | - Jiaxin Quan
- Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Xi'an, China
| | - Xipin Wu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Xi'an, China
| | - Cunxia Li
- Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Xi'an, China
| | - Ming Yue
- Key Laboratory of Resource Biology and Biotechnology in Western China, Northwest University, Xi'an, China
- Xi'an Botanical Garden of Shaanxi Province/Institute of Botany of Shaanxi Province, Xi'an, China
- *Correspondence: Ming Yue,
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5
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Wu G, Chen D, Zhou Z. Contrasting Hydraulic Efficiency and Photosynthesis Strategy in Differential Successional Stages of a Subtropical Forest in a Karst Region. PLANTS 2021; 10:plants10122604. [PMID: 34961075 PMCID: PMC8705339 DOI: 10.3390/plants10122604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/17/2021] [Accepted: 11/22/2021] [Indexed: 11/16/2022]
Abstract
Understanding the successional process from a disturbed forest to a mature forest is essential for species recovery and conservation initiatives. The resource acquisition and drought tolerance of plants can be instructive to predictions of species abundance and distribution for different forests. However, they have not been adequately tested at different successional stages in karst regions. Here, we selected seven dominant species in an early-succession forest and 17 species in a late-succession forest in a karst region of southwestern China. Resource acquisition-related traits such as hydraulic conductivity and photosynthetic rate, and drought tolerance-related traits, including turgor loss point and wood density, were measured. We found that species in the early-succession forest had a higher hydraulic conductance and photosynthetic rate than those in the late-succession forest, while leaf water potential at turgor loss point and wood density showed nonsignificant differences between the two forests. In addition, we observed a significant negative relationship between photosynthetic rate and drought tolerance in the early-succession forest, which was not identified in late-succession forests. Our study indicates that resource acquisition rather than drought tolerance was the key factor explaining plant distributions in forests at different successional stages in karst regions. We also suggest that the resource acquisition and drought tolerance trade-off hypothesis is not always supported for karst region species. Our study could inform about the design of species replacements in successional forests and provide forest management and restoration guidelines for karst regions.
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Fuchs S, Leuschner C, Mathias Link R, Schuldt B. Hydraulic variability of three temperate broadleaf tree species along a water availability gradient in central Europe. THE NEW PHYTOLOGIST 2021; 231:1387-1400. [PMID: 33964029 DOI: 10.1111/nph.17448] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 05/01/2021] [Indexed: 06/12/2023]
Abstract
Plant hydraulic traits are key for understanding and predicting tree drought responses. Information about the degree of the traits' intra-specific variability may guide the selection of drought-resistant genotypes and is crucial for trait-based modelling approaches. For the three temperate minor broadleaf tree species Acer platanoides, Carpinus betulus and Tilia cordata, we measured xylem embolism resistance (P50 ), leaf turgor loss point (PTLP ), specific hydraulic conductivity (KS ), Huber values (HVs), and hydraulic safety margins in adult trees across a precipitation gradient. We further quantified trait variability on different organizational levels (inter-specific to within-canopy variation), and analysed its relationship to climatic and soil water availability. Although we observed a certain intra-specific trait variability (ITV) in safety-related traits (P50 , PTLP ) with higher within-tree and between-tree than between populations variability, the magnitude was small compared to inter-specific differences, which explained 78.4% and 58.3% of the variance in P50 and PTLP , respectively. In contrast, efficiency-related traits (KS , HV) showed a high ITV both within populations and within the crowns of single trees. Surprisingly, the observed ITV of all traits was neither driven by climatic nor soil water availability. In conclusion, the high degree of conservatism in safety-related traits highlights their potential for trait-based modelling approaches.
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Affiliation(s)
- Sebastian Fuchs
- Plant Ecology, Albrecht von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, Goettingen, 37073, Germany
| | - Christoph Leuschner
- Plant Ecology, Albrecht von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, Goettingen, 37073, Germany
- Centre for Biodiversity and Sustainable Land Use (CBL), University of Goettingen, Goettingen, 37075, Germany
| | - Roman Mathias Link
- Plant Ecology, Albrecht von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, Goettingen, 37073, Germany
| | - Bernhard Schuldt
- Plant Ecology, Albrecht von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, Goettingen, 37073, Germany
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7
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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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8
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Hanley PA, Arndt SK, Livesley SJ, Szota C. Relating the climate envelopes of urban tree species to their drought and thermal tolerance. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 753:142012. [PMID: 33207433 DOI: 10.1016/j.scitotenv.2020.142012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 08/18/2020] [Accepted: 08/25/2020] [Indexed: 06/11/2023]
Abstract
Analysing the climate envelope of plant species has been suggested as a tool to predict the vulnerability of tree species in future urban climates. However, there is little evidence that the climate envelope of a plant species directly relates to the drought and thermal tolerance of that species, at least not at the resolution required to identify or rank species vulnerability. Here, we attempted to predict drought and thermal tolerance of commonly used urban tree species using climate variables derived exclusively from open-source global occurrence data. We quantified three drought and thermal tolerance traits for 43 urban tree species in a common garden experiment: stomatal sensitivity to vapour pressure deficit, leaf water potential at the turgor loss point, and leaf thermal tolerance. We then attempted to predict each tolerance trait from variables derived from the climate envelope of each species, using occurrence data from the Global Biodiversity Information Facility. We found no strong relationships between drought and thermal tolerance traits and climatic variables. Across wide environmental gradients, plant tolerance and climate are inherently linked. But our results suggest that climate envelopes determined from species occurrence data alone may not predict drought or thermal tolerance at the resolution required to select tree species for future urban forests. We should focus on identifying the most relevant strategies and traits required to describe tolerance which in combination with climate envelope analysis should ultimately predict growth and mortality of trees in urban landscapes.
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Affiliation(s)
- Paul A Hanley
- School of Ecosystem and Forest Sciences, Faculty of Science, The University of Melbourne, Australia
| | - Stefan K Arndt
- School of Ecosystem and Forest Sciences, Faculty of Science, The University of Melbourne, Australia
| | - Stephen J Livesley
- School of Ecosystem and Forest Sciences, Faculty of Science, The University of Melbourne, Australia
| | - Christopher Szota
- School of Ecosystem and Forest Sciences, Faculty of Science, The University of Melbourne, Australia.
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9
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Mead A, Peñaloza Ramirez J, Bartlett MK, Wright JW, Sack L, Sork VL. Seedling response to water stress in valley oak (Quercus lobata) is shaped by different gene networks across populations. Mol Ecol 2019; 28:5248-5264. [PMID: 31652373 DOI: 10.1111/mec.15289] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 10/21/2019] [Accepted: 10/23/2019] [Indexed: 12/16/2022]
Abstract
Drought is a major stress for plants, creating a strong selection pressure for traits that enable plant growth and survival in dry environments. Many drought responses are conserved species-wide responses, while others vary among populations distributed across heterogeneous environments. We tested how six populations of the widely distributed California valley oak (Quercus lobata) sampled from contrasting climates would differ in their response to soil drying relative to well-watered controls in a common environment by measuring ecophysiological traits in 93 individuals and gene expression (RNA-seq) in 42 individuals. Populations did not differ in their adjustment of turgor loss point during soil drying, suggesting a generalized species-wide response. Differential expression analysis identified 689 genes with a common response to treatment across populations and 470 genes with population-specific responses. Weighted gene co-expression network analysis (WGCNA) identified groups of genes with similar expression patterns that may be regulated together (gene modules). Several gene modules responded differently to water stress among populations, suggesting regional differences in gene network regulation. Populations from sites with a high mean annual temperature responded to the imposed water stress with significantly greater changes in gene module expression, indicating that these populations may be locally adapted to respond to drought. We propose that this variation among valley oak populations provides a mechanism for differential tolerance to the increasingly frequent and severe droughts in California.
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Affiliation(s)
- Alayna Mead
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, CA, USA
| | - Juan Peñaloza Ramirez
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, CA, USA
| | - Megan K Bartlett
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, CA, USA
| | - Jessica W Wright
- USDA Forest Service, Pacific Southwest Research Station, Davis, CA, USA
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, CA, USA.,Institute of the Environment and Sustainability, University of California, Los Angeles, Los Angeles, CA, USA
| | - Victoria L Sork
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, CA, USA.,Institute of the Environment and Sustainability, University of California, Los Angeles, Los Angeles, CA, USA
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10
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Du P, Arndt SK, Farrell C. Is plant survival on green roofs related to their drought response, water use or climate of origin? THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 667:25-32. [PMID: 30825818 DOI: 10.1016/j.scitotenv.2019.02.349] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/22/2019] [Accepted: 02/22/2019] [Indexed: 06/09/2023]
Abstract
Green roofs are novel urban ecosystems with shallow substrate depths and low water availability. Hence, it is critical to select green roof plants that can survive water-deficits, particularly in climates with hot and dry summers. Shrubs are perennial plants which can be drought resistant and may be suitable for green roofs. However, studies about survival and health of shrubs are limited. The aim of this study was to determine whether plant climate of origin aridity, drought response and water use strategies could be used to select shrubs which can survive on green roofs that experience water-deficit. We selected 15 shrub species from a range of climates (dry, mesic and wet) and planted them together in 20 replicate green roof modules with 130 mm deep substrate. We monitored substrate water contents, plant minimum water potentials (ψmin), health (visual score), percentage survival and related survival with their turgor loss point (ψtlp) and water use strategies (evapotranspiration rates in a related glasshouse experiment). We also determined whether plants could recover after dry periods by rewatering after the summer. Mean gravimetric soil water content decreased to approximately 5% after summer drought, which resulted in mortality. Overall, survival ranged between 10% and 100% for the 15 species. However, survival was not related to their ψtlp or water use strategies. While shrubs from more arid climates had lower ψmin in response to dry substrates, this did not result in greater survival and health. Following rewatering, only four shrub species resprouted. Hence, as plant drought response, water use strategy and climate of origin were not strongly related to survival, we suggest survival on green roofs is likely to be determined by a combination of physiological traits. Emergency irrigation for shrubs growing on green roofs in hot and dry climates is recommended during summer to keep them alive.
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Affiliation(s)
- Pengzhen Du
- Department of Ecosystem and Forestry Science, University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria 3121, Australia
| | - Stefan K Arndt
- Department of Ecosystem and Forestry Science, University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria 3121, Australia
| | - Claire Farrell
- Department of Ecosystem and Forestry Science, University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria 3121, Australia.
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11
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Li X, Blackman CJ, Choat B, Rymer PD, Medlyn BE, Tissue DT. Drought tolerance traits do not vary across sites differing in water availability in Banksia serrata (Proteaceae). FUNCTIONAL PLANT BIOLOGY : FPB 2019; 46:624-633. [PMID: 30961787 DOI: 10.1071/fp18238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 02/23/2019] [Indexed: 06/09/2023]
Abstract
Interspecific variation in plant hydraulic traits plays a major role in shaping species distributions across climates, yet variation within species is poorly understood. Here we report on intraspecific variation of hydraulic traits in Banksia serrata (L.f.) sampled from three sites characterised by contrasting climates (warm-wet, warm-dry and cool-wet). Hydraulic characteristics including vulnerability to embolism, hydraulic conductance, pressure-volume traits and key morphological traits were measured. Vulnerability to embolism in leaf and stem, defined by the water potential inducing 50 and 88% loss of hydraulic conductivity (P50 and P88 respectively), did not differ across sites. However, plants from the warm-dry environment exhibited higher stem conductivity (Ks) than the cool-wet environment. Leaf turgor loss point (TLP) did not vary among sites, but warm-dry site plants showed lower leaf capacitance (C*FT) and higher modulus of elasticity (ε) than the other two sites. Plants from the cool-wet site had lower specific leaf area (SLA) and plants from the warm-dry site had lower sapwood density (WD). Overall, key hydraulic traits were generally conserved across populations despite differences in mean site water availability, and the safety-efficiency trade-off was absent in this species. These results suggest that B. serrata has limited ability to adjust hydraulic architecture in response to environmental change and thus may be susceptible to climate change-type drought stress.
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Affiliation(s)
- Ximeng Li
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - Chris J Blackman
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - Paul D Rymer
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - Belinda E Medlyn
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia; and Corresponding author.
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Du P, Arndt SK, Farrell C. Relationships between plant drought response, traits, and climate of origin for green roof plant selection. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2018; 28:1752-1761. [PMID: 30039552 DOI: 10.1002/eap.1782] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 05/01/2018] [Accepted: 05/15/2018] [Indexed: 06/08/2023]
Abstract
The ideal species for green or vegetated roofs should have high water use after rainfall to maximize stormwater retention but also survive periods with low water availability in dry substrates. Shrubs have great potential for green roofs because they have higher rates of water use, and many species are also drought tolerant. However, not all shrub species will be suitable and there may be a trade-off between water use and drought tolerance. We conducted a glasshouse experiment to determine the possible trade-offs between shrub water use for stormwater management and their response to drought conditions. We selected 20 shrubs from a wide range of climates of origin, represented by heat moisture index (HMI) and mean annual precipitation (MAP). Under well-watered (WW) and water-deficit (WD) conditions, we assessed morphological responses to water availability; evapotranspiration rate (ET) and midday water potential (ΨMD ) were used to evaluate species water use and drought response. In response to WD, all 20 shrubs adjusted their morphology and physiology. However, there were no species that simultaneously achieved high rates of water use (high ET) under WW and high drought tolerance (low ΨMD ) under WD conditions. Although some species which had high water use under WW conditions could avoid drought stress (high ΨMD ). Water use was strongly related to plant biomass, total leaf area, and leaf traits (specific leaf area [SLA] and leaf area ratio [LAR]). Conversely, drought response (ΨMD ) was not related to morphological traits. Species' climate of origin was not related to drought response or water use. Drought-avoiding shrubs (high ΨMD ) could optimize rainfall reduction on green roofs. Water use was related to biomass, leaf area, and leaf traits; thus, these traits could be used to assist the selection of shrubs for stormwater mitigation on green roofs. The natural distribution of species was not related to their water use or drought response, which suggests that shrubs from less arid climates may be suitable for use on green roofs. Selecting species based on traits and not climate of origin could both improve green roof performance and biodiversity outcomes by expanding the current plant palette.
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Affiliation(s)
- Pengzhen Du
- Department of Ecosystem and Forestry Science, University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, 3121, Australia
| | - Stefan K Arndt
- Department of Ecosystem and Forestry Science, University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, 3121, Australia
| | - Claire Farrell
- Department of Ecosystem and Forestry Science, University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, 3121, Australia
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Blackman CJ. Leaf turgor loss as a predictor of plant drought response strategies. TREE PHYSIOLOGY 2018; 38:655-657. [PMID: 29726963 DOI: 10.1093/treephys/tpy047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 04/13/2018] [Indexed: 06/08/2023]
Affiliation(s)
- Chris J Blackman
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751 Australia
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Nolan RH, Fairweather KA, Tarin T, Santini NS, Cleverly J, Faux R, Eamus D. Divergence in plant water-use strategies in semiarid woody species. FUNCTIONAL PLANT BIOLOGY : FPB 2017; 44:1134-1146. [PMID: 32480639 DOI: 10.1071/fp17079] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 07/16/2017] [Indexed: 06/11/2023]
Abstract
Partitioning of water resources amongst plant species within a single climate envelope is possible if the species differ in key hydraulic traits. We examined 11 bivariate trait relationships across nine woody species found in the Ti-Tree basin of central Australia. We found that species with limited access to soil moisture, evidenced by low pre-dawn leaf water potential, displayed anisohydric behaviour (e.g. large seasonal fluctuations in minimum leaf water potential), had greater sapwood density and lower osmotic potential at full turgor. Osmotic potential at full turgor was positively correlated with the leaf water potential at turgor loss, which was, in turn, positively correlated with the water potential at incipient stomatal closure. We also observed divergent behaviour in two species of Mulga, a complex of closely related Acacia species which range from tall shrubs to low trees and dominate large areas of arid and semiarid Australia. These Mulga species had much lower minimum leaf water potentials and lower specific leaf area compared with the other seven species. Finally, one species, Hakea macrocarpa A.Cunn ex.R.Br., had traits that may allow it to tolerate seasonal dryness (through possession of small specific leaf area and cavitation resistant xylem) despite exhibiting cellular water relations that were similar to groundwater-dependent species. We conclude that traits related to water transport and leaf water status differ across species that experience differences in soil water availability and that this enables a diversity of species to exist in this low rainfall environment.
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Affiliation(s)
- Rachael H Nolan
- Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia
| | - Kendal A Fairweather
- Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia
| | - Tonantzin Tarin
- Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia
| | - Nadia S Santini
- Centre for Marine Bio-Innovation, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - James Cleverly
- Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia
| | - Ralph Faux
- Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia
| | - Derek Eamus
- Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia
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Farrell C, Szota C, Arndt SK. Does the turgor loss point characterize drought response in dryland plants? PLANT, CELL & ENVIRONMENT 2017; 40:1500-1511. [PMID: 28342210 DOI: 10.1111/pce.12948] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 02/22/2017] [Accepted: 02/24/2017] [Indexed: 05/18/2023]
Abstract
The water potential at turgor loss point (Ψtlp ) has been suggested as a key functional trait for determining plant drought tolerance, because of its close relationship with stomatal closure. Ψtlp may indicate drought tolerance as plants, which maintain gas exchange at lower midday water potentials as soil water availability declines also have lower Ψtlp . We evaluated 17 species from seasonally dry habitats, representing a range of life-forms, under well-watered and drought conditions, to determine how Ψtlp relates to stomatal sensitivity (pre-dawn water potential at stomatal closure: Ψgs0 ) and drought strategy (degree of isohydry or anisohydry; ΔΨMD between well-watered conditions and stomatal closure). Although Ψgs0 was related to Ψtlp , Ψgs0 was better related to drought strategy (ΔΨMD ). Drought avoiders (isohydric) closed stomata at water potentials higher than their Ψtlp ; whereas, drought tolerant (anisohydric) species maintained stomatal conductance at lower water potentials than their Ψtlp and were more dehydration tolerant. There was no significant relationship between Ψtlp and ΔΨMD . While Ψtlp has been related to biome water availability, we found that Ψtlp did not relate strongly to stomatal closure or drought strategy, for either drought avoiders or tolerators. We therefore suggest caution in using Ψtlp to predict vulnerability to drought.
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Affiliation(s)
- Claire Farrell
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, 3121, Australia
| | - Christopher Szota
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, 3121, Australia
| | - Stefan K Arndt
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, 3121, Australia
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Bourne AE, Creek D, Peters JMR, Ellsworth DS, Choat B. Species climate range influences hydraulic and stomatal traits in Eucalyptus species. ANNALS OF BOTANY 2017; 120:123-133. [PMID: 28369162 PMCID: PMC5737682 DOI: 10.1093/aob/mcx020] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 02/17/2017] [Indexed: 05/05/2023]
Abstract
BACKGROUND AND AIMS Plant hydraulic traits influence the capacity of species to grow and survive in water-limited environments, but their comparative study at a common site has been limited. The primary aim of this study was to determine whether selective pressures on species originating in drought-prone environments constrain hydraulic traits among related species grown under common conditions. METHODS Leaf tissue water relations, xylem anatomy, stomatal behaviour and vulnerability to drought-induced embolism were measured on six Eucalyptus species growing in a common garden to determine whether these traits were related to current species climate range and to understand linkages between the traits. KEY RESULTS Hydraulically weighted xylem vessel diameter, leaf turgor loss point, the water potential at stomatal closure and vulnerability to drought-induced embolism were significantly ( P < 0·05) correlated with climate parameters from the species range. There was a co-ordination between stem and leaf parameters with the water potential at turgor loss, 12 % loss of conductivity and the point of stomatal closure significantly correlated. CONCLUSIONS The correlation of hydraulic, stomatal and anatomical traits with climate variables from the species' original ranges suggests that these traits are genetically constrained. The conservative nature of xylem traits in Eucalyptus trees has important implications for the limits of species responses to changing environmental conditions and thus for species survival and distribution into the future, and yields new information for physiological models.
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Affiliation(s)
- Aimee E. Bourne
- Western Sydney University, Hawkesbury Institute for the Environment, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - Danielle Creek
- Western Sydney University, Hawkesbury Institute for the Environment, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - Jennifer M. R. Peters
- Western Sydney University, Hawkesbury Institute for the Environment, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - David S. Ellsworth
- Western Sydney University, Hawkesbury Institute for the Environment, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - Brendan Choat
- Western Sydney University, Hawkesbury Institute for the Environment, Locked Bag 1797, Penrith, NSW 2751, Australia
- For correspondence. E-mail
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