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Fickle JC, Pratt RB, Jacobsen AL. Xylem structure and hydraulic function in roots and stems of chaparral shrub species from high and low elevation in the Sierra Nevada, California. Physiol Plant 2023; 175:e13970. [PMID: 37401910 DOI: 10.1111/ppl.13970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 06/16/2023] [Accepted: 06/25/2023] [Indexed: 07/05/2023]
Abstract
Xylem structure and hydraulics were compared between individuals at lower and upper elevation distribution limits for five chaparral shrub species along a steep transect in the southern Sierra Nevada, California, USA. Higher-elevation plants experienced frequent winter freeze-thaw events and increased precipitation. We hypothesized that environmental differences would lead to xylem trait differences between high and low elevations, but predictions were complicated because both water stress (low elevation) and freeze-thaw events (high elevation) may select for similar traits, such as narrow vessel diameter. We found significant changes in the ratio of stem xylem area to leaf area (Huber value) between elevations, with more xylem area required to support leaves at low elevations. Co-occurring species significantly differed in their xylem traits, suggesting diverse strategies to cope with the highly seasonal environment of this Mediterranean-type climate region. Roots were more hydraulically efficient and more vulnerable to embolism relative to stems, potentially due to roots being buffered from freeze-thaw stress, which allows them to maintain wider diameter vessels. Knowledge of the structure and function of both roots and stems is likely important in understanding whole-plant response to environmental gradients.
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Affiliation(s)
- Jaycie C Fickle
- Department of Biology, California State University, Bakersfield, California, USA
- University of Utah, Salt Lake City, Utah, USA
| | - R Brandon Pratt
- Department of Biology, California State University, Bakersfield, California, USA
| | - Anna L Jacobsen
- Department of Biology, California State University, Bakersfield, California, USA
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2
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An YD, Roddy AB, Zhang TH, Jiang GF. Hydraulic differences between flowers and leaves are driven primarily by pressure-volume traits and water loss. Front Plant Sci 2023; 14:1130724. [PMID: 37324689 PMCID: PMC10264769 DOI: 10.3389/fpls.2023.1130724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 05/16/2023] [Indexed: 06/17/2023]
Abstract
Flowers are critical for successful reproduction and have been a major axis of diversification among angiosperms. As the frequency and severity of droughts are increasing globally, maintaining water balance of flowers is crucial for food security and other ecosystem services that rely on flowering. Yet remarkably little is known about the hydraulic strategies of flowers. We characterized hydraulic strategies of leaves and flowers of ten species by combining anatomical observations using light and scanning electron microscopy with measurements of hydraulic physiology (minimum diffusive conductance (g min) and pressure-volume (PV) curves parameters). We predicted that flowers would exhibit higher g min and higher hydraulic capacitance than leaves, which would be associated with differences in intervessel pit traits because of their different hydraulic strategies. We found that, compared to leaves, flowers exhibited: 1) higher g min, which was associated with higher hydraulic capacitance (C T); 2) lower variation in intervessel pit traits and differences in pit membrane area and pit aperture shape; and 3) independent coordination between intervessel pit traits and other anatomical and physiological traits; 4) independent evolution of most traits in flowers and leaves, resulting in 5) large differences in the regions of multivariate trait space occupied by flowers and leaves. Furthermore, across organs intervessel pit trait variation was orthogonal to variation in other anatomical and physiological traits, suggesting that pit traits represent an independent axis of variation that have as yet been unquantified in flowers. These results suggest that flowers, employ a drought-avoidant strategy of maintaining high capacitance that compensates for their higher g min to prevent excessive declines in water potentials. This drought-avoidant strategy may have relaxed selection on intervessel pit traits and allowed them to vary independently from other anatomical and physiological traits. Furthermore, the independent evolution of floral and foliar anatomical and physiological traits highlights their modular development despite being borne from the same apical meristem.
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Affiliation(s)
- Yi-Dong An
- Guangxi Key Laboratory of Forest Ecology and Conservation, Guangxi Colleges and Universities Key Laboratory for Cultivation and Utilization of Subtropical Forest Plantation, and State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Nanning, Guangxi, China
| | - Adam B. Roddy
- Institute of Environment, Department of Biological Sciences, Florida International University, Miami, FL, United States
| | - Tian-Hao Zhang
- Guangxi Key Laboratory of Forest Ecology and Conservation, Guangxi Colleges and Universities Key Laboratory for Cultivation and Utilization of Subtropical Forest Plantation, and State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Nanning, Guangxi, China
| | - Guo-Feng Jiang
- Guangxi Key Laboratory of Forest Ecology and Conservation, Guangxi Colleges and Universities Key Laboratory for Cultivation and Utilization of Subtropical Forest Plantation, and State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Nanning, Guangxi, China
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3
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Avila RT, Kane CN, Batz TA, Trabi C, Damatta FM, Jansen S, McAdam SAM. The relative area of vessels in xylem correlates with stem embolism resistance within and between genera. Tree Physiol 2023; 43:75-87. [PMID: 36070431 DOI: 10.1093/treephys/tpac110] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/30/2022] [Indexed: 06/15/2023]
Abstract
The resistance of xylem conduits to embolism is a major factor defining drought tolerance and can set the distributional limits of species across rainfall gradients. Recent work suggests that the proximity of vessels to neighbors increases the vulnerability of a conduit. We therefore investigated whether the relative vessel area of xylem correlates with intra- and inter-generic variation in xylem embolism resistance in species pairs or triplets from the genera Acer, Cinnamomum, Ilex, Quercus and Persea, adapted to environments differing in aridity. We used the optical vulnerability method to assess embolism resistance in stems and conducted anatomical measurements on the xylem in which embolism resistance was quantified. Vessel lumen fraction (VLF) correlated with xylem embolism resistance across and within genera. A low VLF likely increases the resistance to gas movement between conduits, by diffusion or advection, whereas a high VLF enhances gas transport thorough increased conduit-to-conduit connectivity and reduced distances between conduits and therefore the likelihood of embolism propagation. We suggest that the rate of gas movement due to local pressure differences and xylem network connectivity is a central driver of embolism propagation in angiosperm vessels.
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Affiliation(s)
- Rodrigo T Avila
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36570-900, Brazil
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
| | - Cade N Kane
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
| | - Timothy A Batz
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
| | - Christophe Trabi
- Faculty of Natural Sciences, Institute of Systematic Botany and Ecology, Ulm University, Ulm, Baden-Württemberg 89081, Germany
| | - Fábio M Damatta
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36570-900, Brazil
| | - Steven Jansen
- Faculty of Natural Sciences, Institute of Systematic Botany and Ecology, Ulm University, Ulm, Baden-Württemberg 89081, Germany
| | - Scott A M McAdam
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
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4
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Nie ZF, Liao ZQ, Yao GQ, Tian XQ, Bi MH, Teixeira da Silva JA, Gao TP, Fang XW. Divergent stem hydraulic strategies of Caragana korshinskii resprouts following a disturbance. Tree Physiol 2022; 42:325-336. [PMID: 34387352 DOI: 10.1093/treephys/tpab108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
Resprouting plants are distributed in many vegetation communities worldwide. With increasing resprout age post-severe-disturbance, new stems grow rapidly at their early age, and decrease in their growth with gradually decreasing water status thereafter. However, there is little knowledge about how stem hydraulic strategies and anatomical traits vary post-disturbance. In this study, the stem water potential (Ψstem), maximum stem hydraulic conductivity (Kstem-max), water potential at 50% loss of hydraulic conductivity (Kstem P50) and anatomical traits of Caragana korshinkii resprouts were measured during a 1- to 13-year post-disturbance period. We found that the Kstem-max decreased with resprout age from 1-year-old resprouts (84.2 mol m-1 s-1 MPa-1) to 13-year-old resprouts (54.2 mol m-1 s-1 MPa-1) as a result of decreases in the aperture fraction (Fap) and the sum of aperture area on per unit intervessel wall area (Aap). The Kstem P50 of the resprouts decreased from 1-year-old resprouts (-1.8 MPa) to 13-year-old resprouts (-2.9 MPa) as a result of increases in vessel implosion resistance (t/b)2, wood density (WD), vessel grouping index (GI) and decreases in Fap and Aap. These shifts in hydraulic structure and function resulted in an age-based divergence in hydraulic strategies i.e., a change from an acquisitive strategy to a conservative strategy, with increasing resprout age post-disturbance.
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Affiliation(s)
- Zheng-Fei Nie
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Zhong-Qiang Liao
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Guang-Qian Yao
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Xue-Qian Tian
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Min-Hui Bi
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | | | - Tian-Peng Gao
- School of Biological and Environmental Engineering, Xi'an University, Xi'an 710065, China
| | - Xiang-Wen Fang
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
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Song Y, Poorter L, Horsting A, Delzon S, Sterck F. Pit and tracheid anatomy explain hydraulic safety but not hydraulic efficiency of 28 conifer species. J Exp Bot 2022; 73:1033-1048. [PMID: 34626106 PMCID: PMC8793876 DOI: 10.1093/jxb/erab449] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 10/07/2021] [Indexed: 05/16/2023]
Abstract
Conifers face increased drought mortality risks because of drought-induced embolism in their vascular system. Variation in embolism resistance may result from species differences in pit structure and function, as pits control the air seeding between water-transporting conduits. This study quantifies variation in embolism resistance and hydraulic conductivity for 28 conifer species grown in a 50-year-old common garden experiment and assesses the underlying mechanisms. Conifer species with a small pit aperture, high pit aperture resistance, and large valve effect were more resistant to embolism, as they all may reduce air seeding. Surprisingly, hydraulic conductivity was only negatively correlated with tracheid cell wall thickness. Embolism resistance and its underlying pit traits related to pit size and sealing were more strongly phylogenetically controlled than hydraulic conductivity and anatomical tracheid traits. Conifers differed in hydraulic safety and hydraulic efficiency, but there was no trade-off between safety and efficiency because they are driven by different xylem anatomical traits that are under different phylogenetic control.
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Affiliation(s)
- Yanjun Song
- Forest Ecology and Forest Management Group, Wageningen University and Research, PO Box 47, 6700 AA, Wageningen, The Netherlands
| | - Lourens Poorter
- Forest Ecology and Forest Management Group, Wageningen University and Research, PO Box 47, 6700 AA, Wageningen, The Netherlands
| | - Angelina Horsting
- Forest Ecology and Forest Management Group, Wageningen University and Research, PO Box 47, 6700 AA, Wageningen, The Netherlands
| | - Sylvain Delzon
- University of Bordeaux, INRA, UMR BIOGECO, 33450 Talence, France
| | - Frank Sterck
- Forest Ecology and Forest Management Group, Wageningen University and Research, PO Box 47, 6700 AA, Wageningen, The Netherlands
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6
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Fontes CG, Pinto‐Ledezma J, Jacobsen AL, Pratt RB, Cavender‐Bares J. Adaptive variation among oaks in wood anatomical properties is shaped by climate of origin and shows limited plasticity across environments. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13964] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Clarissa G. Fontes
- Department of Ecology, Evolution and Behavior University of Minnesota Saint Paul MN USA
| | - Jesús Pinto‐Ledezma
- Department of Ecology, Evolution and Behavior University of Minnesota Saint Paul MN USA
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7
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Baer AB, Fickle JC, Medina J, Robles C, Pratt RB, Jacobsen AL. Xylem biomechanics, water storage, and density within roots and shoots of an angiosperm tree species. J Exp Bot 2021; 72:7984-7997. [PMID: 34410349 DOI: 10.1093/jxb/erab384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 08/17/2021] [Indexed: 06/13/2023]
Abstract
Xylem is a complex tissue that forms the bulk of tree bodies and has several functions, including to conduct water, store water and nutrients, and biomechanically support the plant body. We examined how xylem functional traits varied at different positions within 9-year-old Populus balsamifera subsp. trichocarpa. Whole trees were excavated, and xylem samples were collected at 1-m increments along the main root-to-shoot axis of six trees, from root tip to shoot tip. We examined biomechanical and water-storage traits of the xylem, including using a non-invasive imaging technique to examine water content within long, intact branches (high-resolution computed tomography; microCT). Xylem density, strength, and stiffness were greater in shoots than roots. Along the main root-to-shoot axis, xylem strength and stiffness were greatest at shoot tips, and the tissue became linearly weaker and less stiff down the plant and through the root. Roots had greater water storage with lower biomechanical support, and shoots had biomechanically stronger and stiffer xylem with lower water storage. These findings support trade-offs among xylem functions between roots and shoots. Understanding how xylem functions differ throughout tree bodies is important in understanding whole-tree functioning and how terrestrial plants endure numerous environmental challenges over decades of growth.
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Affiliation(s)
- Alex B Baer
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
| | - Jaycie C Fickle
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
| | - Jackeline Medina
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
| | - Catherine Robles
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
| | - R Brandon Pratt
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
| | - Anna L Jacobsen
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
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8
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Yao GQ, Nie ZF, Zeng YY, Waseem M, Hasan MM, Tian XQ, Liao ZQ, Siddique KHM, Fang XW. A clear trade-off between leaf hydraulic efficiency and safety in an aridland shrub during regrowth. Plant Cell Environ 2021; 44:3347-3357. [PMID: 34327717 DOI: 10.1111/pce.14156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 07/16/2021] [Accepted: 07/18/2021] [Indexed: 06/13/2023]
Abstract
It has been suggested that a trade-off between hydraulic efficiency and safety is related to drought adaptation across species. However, whether leaf hydraulic efficiency is sacrificed for safety during woody resprout regrowth after crown removal is not well understood. We measured leaf water potential (ψleaf ) at predawn (ψpd ) and midday (ψmid ), leaf maximum hydraulic conductance (Kleaf-max ), ψleaf at induction 50% loss of Kleaf-max (Kleaf P50 ), leaf area-specific whole-plant hydraulic conductance (LSC), leaf vein structure and turgor loss point (πtlp ) in 1- to 13-year-old resprouts of the aridland shrub (Caragana korshinskii). ψpd was similar, ψmid and Kleaf P50 became more negative, and Kleaf-max decreased in resprouts with the increasing age; thus, leaf hydraulic efficiency clearly traded off against safety. The difference between ψmid and Kleaf P50 , leaf hydraulic safety margin, increased gradually with increasing resprout age. More negative ψmid and Kleaf P50 were closely related to decreasing LSC and more negative πtlp , respectively, and the decreasing Kleaf-max arose from the lower minor vein density and the narrower midrib xylem vessels. Our results showed that a clear trade-off between leaf hydraulic efficiency and safety helps C. korshinskii resprouts adapt to increasing water stress as they approach final size.
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Affiliation(s)
- Guang-Qian Yao
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province, China
| | - Zheng-Fei Nie
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province, China
| | - Yuan-Yuan Zeng
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province, China
| | - Muhammad Waseem
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province, China
| | - Md Mahadi Hasan
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province, China
| | - Xue-Qian Tian
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province, China
| | - Zhong-Qiang Liao
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province, China
| | - Kadambot H M Siddique
- The UWA Institute of Agriculture and UWA School of Agriculture and Environment, The University of Western Australia, Perth, Western Australia, Australia
| | - Xiang-Wen Fang
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, Gansu Province, China
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Avila RT, Cardoso AA, Batz TA, Kane CN, DaMatta FM, McAdam SAM. Limited plasticity in embolism resistance in response to light in leaves and stems in species with considerable vulnerability segmentation. Physiol Plant 2021; 172:2142-2152. [PMID: 33942915 DOI: 10.1111/ppl.13450] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 04/23/2021] [Accepted: 04/30/2021] [Indexed: 06/12/2023]
Abstract
Xylem resistance to embolism is a key metric determining plant survival during drought. Yet, we have a limited understanding of the degree of plasticity in vulnerability to embolism. Here, we tested whether light availability influences embolism resistance in leaves and stems. The optical vulnerability method was used to assess stem and leaf resistance to embolism in Phellodendron amurense and Ilex verticillata acclimated to sun and shade microenvironments within the same canopy. In both species, we found considerable segmentation in xylem resistance to embolism between leaves and stems, but only minor acclimation in response to light availability. With the addition of a third species, Betula pubescens, which shows no vulnerability segmentation, we sought to investigate xylem anatomical traits that might correlate with strong vulnerability segmentation. We found a correlation between the area fraction of vessels in the xylem and embolism resistance across species and tissue types. Our results suggest that minimal acclimation of embolism resistance occurs in response to light environment in the same individual and that the degree of vulnerability segmentation between leaves and stems might be determined by the vessel lumen fraction of the xylem.
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Affiliation(s)
- Rodrigo T Avila
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Brazil
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Amanda A Cardoso
- Instituto de Ciências da Natureza, Universidade Federal de Alfenas, Alfenas, Brazil
| | - Timothy A Batz
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Cade N Kane
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Fábio M DaMatta
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Brazil
| | - Scott A M McAdam
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
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10
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van Blerk JJ, West AG, Altwegg R, Hoffman MT. Does a trade-off between growth plasticity and resource conservatism mediate post-fire shrubland responses to rainfall seasonality? New Phytol 2021; 230:1407-1420. [PMID: 33524198 DOI: 10.1111/nph.17246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 01/27/2021] [Indexed: 06/12/2023]
Abstract
Growth plasticity may allow fire-prone species to maximize their recovery rates during temporary, sporadic periods of rainfall availability in the post-fire environment. However, moisture-driven growth plasticity could be maladaptive in nutrient-limited environments that require tighter control of growth and resource use. We investigated whether a trade-off between plasticity and conservatism mediates growth responses to altered rainfall seasonality in neighbouring shrubland communities that occupy different soils. We monitored post-fire vegetation regrowth in two structurally similar, Mediterranean-type shrublands for 3 years. We investigated the effects of experimentally altered rainfall seasonality on post-fire species' growth rates. We found that moisture-driven growth plasticity was higher among species occupying the fertile soils of the renosterveld site relative to those occupying the nutrient-poor soils of the fynbos site. This resulted in higher overall responsiveness of post-fire recovery patterns in renosterveld to experimental shifts in rainfall seasonality. In post-fire shrubland communities, the trade-off between moisture-dependent growth plasticity and resource conservatism could be mediated by soil nutrient availability. Therefore, edaphic differences between structurally similar shrublands could lead to differences in their sensitivity to post-fire rainfall seasonality.
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Affiliation(s)
- Justin J van Blerk
- Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa
| | - Adam G West
- Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa
| | - Res Altwegg
- Centre for Statistics in Ecology, Environment and Conservation, Department of Statistical Sciences, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa
| | - M Timm Hoffman
- Plant Conservation Unit, Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa
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11
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Abstract
Chaparral shrubs in southern California may be vulnerable to frequent fire and severe drought. Drought may diminish postfire recovery or worsen impact of short-interval fires. Field-based studies have not shown the extent and magnitude of drought effects on recovery, which may vary among chaparral types and climatic zones. We tracked regional patterns of shrub cover based on June-solstice Landsat Normalized Difference Vegetation Index series, compared between the periods 1984-1989 and 2014-2018. High spatial resolution ortho-imagery was used to map shrub cover in distributed sample plots, to empirically constrain the Landsat-based estimates of mature-stage lateral canopy recovery. We evaluated precipitation, climatic water deficit (CWD), and Palmer Drought Severity Index in summer and wet seasons preceding and following fire, as regional predictors of recovery in 982 locations between the Pacific Coast and inland deserts. Wet-season CWD was the strongest drought-metric predictor of recovery, contributing 34-43 % of explanatory power in multivariate regressions (R 2 =0.16-0.42). Limited recovery linked to drought was most prevalent in transmontane chamise chaparral; impacts were minor in montane areas, and in mixed and montane chaparral types. Elevation was correlated negatively to recovery of transmontane chamise; this may imply acute drought sensitivity in resprouts which predominate seedlings at higher elevations. Landsat Visible Atmospherically Resistant Index (sensitive to live-fuel moisture) was evaluated as a landscape-scale predictor of recovery and explained the greatest amount of variance in a multivariate regression (R 2 = 0.53). We find that drought severity was more closely related to recovery differences among twice-burned sites than was fire-return interval. Summarily, drought has a major role in long-term shrub cover reduction within xeric chaparral ecotones bounding the Mojave Desert and Colorado Desert, likely in tandem with other global change stressors.
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Affiliation(s)
- Emanuel A Storey
- Department of Geography, San Diego State University, 5500 Campanile Drive, San Diego, California 92182, USA
| | - Douglas A Stow
- Department of Geography, San Diego State University, 5500 Campanile Drive, San Diego, California 92182, USA
| | - Dar A Roberts
- Department of Geography, University of California-Santa Barbara, 3611 Ellison Hall, Santa Barbara, California 93106, USA
| | - John F O'Leary
- Department of Geography, San Diego State University, 5500 Campanile Drive, San Diego, California 92182, USA
| | - Frank W Davis
- Bren School of Environmental Science and Management, University of California-Santa Barbara, 2400 Bren Hall, Santa Barbara, California 93106, USA
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12
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Olson M, Rosell JA, Martínez‐Pérez C, León‐Gómez C, Fajardo A, Isnard S, Cervantes‐Alcayde MA, Echeverría A, Figueroa‐Abundiz VA, Segovia‐Rivas A, Trueba S, Vázquez‐Segovia K. Xylem vessel‐diameter–shoot‐length scaling: ecological significance of porosity types and other traits. ECOL MONOGR 2020. [DOI: 10.1002/ecm.1410] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Mark Olson
- Instituto de Biología Universidad Nacional Autónoma de México Tercer Circuito s/n de Ciudad Universitaria Ciudad de México 04510 México
| | - Julieta A. Rosell
- Laboratorio Nacional de Ciencias de la Sostenibilidad Instituto de Ecología Universidad Nacional Autónoma de México Tercer Circuito s/n de Ciudad Universitaria Ciudad de México 04510 México
| | - Cecilia Martínez‐Pérez
- Instituto de Biología Universidad Nacional Autónoma de México Tercer Circuito s/n de Ciudad Universitaria Ciudad de México 04510 México
| | - Calixto León‐Gómez
- Instituto de Biología Universidad Nacional Autónoma de México Tercer Circuito s/n de Ciudad Universitaria Ciudad de México 04510 México
| | - Alex Fajardo
- Centro de Investigación en Ecosistemas de la Patagonia (CIEP) Camino Baguales s/n Coyhaique 5951601 Chile
| | - Sandrine Isnard
- Botanique et Modélisation de l’Architecture de Plantes de des Végétations Institut de Recherche pourle Développement Centre de Coopération Internationale en Recherche Agronomique pour le Développement Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique Université de Montpellier Montpellier 34398 France
- Botanique et Modélisation de l’Architecture de Plantes de des Végétations Institut de Recherche pourle Développement Herbier de Nouvelle‐Caledonia Nouméa 98848 New Caledonia
| | - María Angélica Cervantes‐Alcayde
- Instituto de Biología Universidad Nacional Autónoma de México Tercer Circuito s/n de Ciudad Universitaria Ciudad de México 04510 México
| | - Alberto Echeverría
- Instituto de Biología Universidad Nacional Autónoma de México Tercer Circuito s/n de Ciudad Universitaria Ciudad de México 04510 México
| | - Víctor A. Figueroa‐Abundiz
- Instituto de Biología Universidad Nacional Autónoma de México Tercer Circuito s/n de Ciudad Universitaria Ciudad de México 04510 México
| | - Alí Segovia‐Rivas
- Instituto de Biología Universidad Nacional Autónoma de México Tercer Circuito s/n de Ciudad Universitaria Ciudad de México 04510 México
| | - Santiago Trueba
- Botanique et Modélisation de l’Architecture de Plantes de des Végétations Institut de Recherche pourle Développement Centre de Coopération Internationale en Recherche Agronomique pour le Développement Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique Université de Montpellier Montpellier 34398 France
- Botanique et Modélisation de l’Architecture de Plantes de des Végétations Institut de Recherche pourle Développement Herbier de Nouvelle‐Caledonia Nouméa 98848 New Caledonia
- School of Forestry & Environmental Studies Yale University New Haven Connecticut 06511 USA
| | - Karen Vázquez‐Segovia
- Laboratorio Nacional de Ciencias de la Sostenibilidad Instituto de Ecología Universidad Nacional Autónoma de México Tercer Circuito s/n de Ciudad Universitaria Ciudad de México 04510 México
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13
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Cary KL, Ranieri GM, Pittermann J. Xylem form and function under extreme nutrient limitation: an example from California's pygmy forest. New Phytol 2020; 226:760-769. [PMID: 31900931 DOI: 10.1111/nph.16405] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 12/19/2019] [Indexed: 06/10/2023]
Abstract
Xylem anatomy and function have large implications for plant growth as well as survival during drought, but the impact of nutrient limitation on xylem is not fully understood. This study examines the pygmy forest in California, a plant community that experiences negligible water stress but is severely stunted by low-nutrient and acidic soil, to investigate how nutrient limitation affects xylem function. Thirteen key anatomical and hydraulic traits of stems of four species were compared between pygmy forest plants and nearby conspecifics growing on richer soil. Resistance to cavitation (P50 ), a critical trait for predicting survival during drought, had highly species-specific responses: in one species, pygmy plants had a 26% decrease in cavitation resistance compared to higher-nutrient conspecifics, while in another species, pygmy plants had a 56% increase in cavitation resistance. Other traits responded to nutrient limitation more consistently: pygmy plants had smaller xylem conduits and higher leaf-specific conductivity (KL ) than conspecific controls. Edaphic stress, even in the absence of water stress, altered xylem structure and thus had substantial impacts on water transport. Importantly, nutrient limitation shifted cavitation resistance in a species-specific and unpredictable manner; this finding has implications for the assessment of cavitation resistance in other natural systems.
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Affiliation(s)
- Katharine L Cary
- University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, USA
| | - Gina M Ranieri
- University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, USA
| | - Jarmila Pittermann
- University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, USA
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14
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Li S, Hao GY, Niinemets Ü, Harley PC, Wanke S, Lens F, Zhang YJ, Cao KF. The effects of intervessel pit characteristics on xylem hydraulic efficiency and photosynthesis in hemiepiphytic and non-hemiepiphytic Ficus species. Physiol Plant 2019; 167:661-675. [PMID: 30637766 DOI: 10.1111/ppl.12923] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 12/21/2018] [Accepted: 01/08/2019] [Indexed: 06/09/2023]
Abstract
Xylem vulnerability to cavitation and hydraulic efficiency are directly linked to fine-scale bordered pit features in water-conducting cells of vascular plants. However, it is unclear how pit characteristics influence water transport and carbon economy in tropical species. The primary aim of this study was to evaluate functional implications of changes in pit characteristics for water relations and photosynthetic traits in tropical Ficus species with different growth forms (i.e. hemiepiphytic and non-hemiepiphytic) grown under common conditions. Intervessel pit characteristics were measured using scanning electron microscopy in five hemiepiphytic and five non-hemiepiphytic Ficus species to determine whether these traits were related to hydraulics, leaf photosynthesis, stomatal conductance and wood density. Ficus species varied greatly in intervessel pit structure, hydraulic conductivity and leaf physiology, and clear differences were observed between the two growth forms. The area and diameter of pit aperture were negatively correlated with sapwood-specific hydraulic conductivity, mass-based net assimilation rate, stomatal conductance (gs ), intercellular CO2 concentration (Ci ) and the petiole vessel lumen diameters (Dv ), but positively correlated with wood density. Pit morphology was only negatively correlated with sapwood- and leaf-specific hydraulic conductivity and Dv . Pit density was positively correlated with gs , Ci and Dv , but negatively with intrinsic leaf water-use efficiency. Pit and pit aperture shape were not significantly correlated with any of the physiological traits. These findings indicate a significant role of pit characteristics in xylem water transport, carbon assimilation and ecophysiological adaptation of Ficus species in tropical rain forests.
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Affiliation(s)
- Shuai Li
- Department of Plant Physiology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu, 51014, Estonia
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
| | - Guang-You Hao
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Liaoning, Shenyang, 110016, China
| | - Ülo Niinemets
- Department of Plant Physiology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu, 51014, Estonia
| | - Peter C Harley
- Department of Plant Physiology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu, 51014, Estonia
| | - Stefan Wanke
- Institut für Botanik, Technische Universität Dresden, Dresden, 01062, Germany
| | - Frederic Lens
- Naturalis Biodiversity Center, Leiden University, PO Box 9517, 2300RA, Leiden, The Netherlands
| | - Yong-Jiang Zhang
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
- School of Biology and Ecology, University of Maine, Orono, ME, 04469, USA
| | - Kun-Fang Cao
- College of Forestry, Guangxi University, Plant Ecophysiology and Evolution Group, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Key Laboratory of Forest Ecology and Conservation, Nanning, Guangxi, 530004, China
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15
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Matzner SL, Ronning N, Hawkinson J, Cummiskey T, Buchanan J, Miller E, Carlisle G. Does acclimation in cavitation resistance due to mechanical perturbation support the pit area or conduit reinforcement hypotheses in Phaseolus vulgaris? Physiol Plant 2019; 167:378-390. [PMID: 30537192 PMCID: PMC6557702 DOI: 10.1111/ppl.12895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 12/01/2018] [Accepted: 12/04/2018] [Indexed: 05/23/2023]
Abstract
Two Phaseolus vulgaris L. cultivars were exposed to reduced water and stem mechanical perturbation treatments (flexing) to determine if acclimation to these treatments induced hydraulic changes, altered cavitation resistance and changed stem mechanical properties. Additionally, this study sought to determine if changes in cavitation resistance would support the pit area or conduit reinforcement hypotheses. Flexing reduced biomass, leaf area, xylem vessel area and hydraulic conductivity. One cultivar had greater measures of stem strength and cavitation resistance. Flexing increased cavitation resistance (P50 ) but did not increase Young's modulus, rigidity or flexural strength on dried stems. Stem rigidity and basal diameter were correlated with leaf mass. The ratio of conduit wall thickness to span [(t/b)h 2 ] increased under high water and flexing treatments while rigidity decreased for one cultivar exposed to both flexing and lower water suggesting an inability to compensate for two simultaneous stresses. Although P50 was not correlated with measures of mechanical strength, P50 was correlated with vessel diameter, consistent with the pit area hypothesis. This study confirmed that mechanical perturbation can impact xylem structural properties and result in altered plant water flow characteristics and cavitation resistance. Long-term hydraulic acclimation in these herbaceous annuals was constrained by similar tradeoffs that constrain hydraulic properties across species.
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16
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De Baerdemaeker NJF, Arachchige KNR, Zinkernagel J, Van den Bulcke J, Van Acker J, Schenk HJ, Steppe K. The stability enigma of hydraulic vulnerability curves: addressing the link between hydraulic conductivity and drought-induced embolism. Tree Physiol 2019; 39:1646-1664. [PMID: 31274162 DOI: 10.1093/treephys/tpz078] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 03/29/2019] [Accepted: 06/13/2019] [Indexed: 05/29/2023]
Abstract
Maintaining xylem water transport under drought is vital for plants, but xylem failure does occur when drought-induced embolisms form and progressively spread through the xylem. The hydraulic method is widely considered the gold standard to quantify drought-induced xylem embolism. The method determines hydraulic conductivity (Kh) in cut branch samples, dehydrated to specific drought levels, by pushing water through them. The technique is widely considered for its reliable Kh measurements, but there is some uncertainty in the literature over how to define stable Kh and how that relates to the degree of xylem embolism formation. Therefore, the most common setup for this method was extended to measure four parameters: (i) inlet Kh, (ii) outlet Kh, (iii) radial flow from xylem to surrounding living tissue and (iv) the pressure difference across the sample. From a strictly theoretical viewpoint, hydraulic steady state, where inflow equals outflow and radial flow is zero, will result in stable Kh. Application of the setup to Malus domestica Borkh. branches showed that achieving hydraulic steady state takes considerable time (up to 300 min) and that time to reach steady state increased with declining xylem water potentials. During each experimental run, Kh and xylem water potentials dynamically increased, which was supported by X-ray computed microtomography visualizations of embolism refilling under both high- (8 kPa) and low-pressure (2 kPa) heads. Supplying pressurized water can hence cause artificial refilling of vessels, which makes it difficult to achieve a truly stable Kh in partially embolized xylem.
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Affiliation(s)
- Niels J F De Baerdemaeker
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
| | | | - Jana Zinkernagel
- Department of Vegetable Crops, Hochschule Geisenheim University, 65366 Geisenheim, Germany
| | - Jan Van den Bulcke
- UGCT-Laboratory of Wood Technology, Department of Environment, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
| | - Joris Van Acker
- UGCT-Laboratory of Wood Technology, Department of Environment, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
| | - H Jochen Schenk
- Plants and H2O Laboratory, Department of Biological Science, California State University Fullerton, PO Box 6850, Fullerton, CA 92834-6850, USA
| | - Kathy Steppe
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
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17
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Menezes‐Silva PE, Loram‐Lourenço L, Alves RDFB, Sousa LF, Almeida SEDS, Farnese FS. Different ways to die in a changing world: Consequences of climate change for tree species performance and survival through an ecophysiological perspective. Ecol Evol 2019; 9:11979-11999. [PMID: 31695903 PMCID: PMC6822037 DOI: 10.1002/ece3.5663] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 08/22/2019] [Accepted: 08/28/2019] [Indexed: 01/10/2023] Open
Abstract
Anthropogenic activities such as uncontrolled deforestation and increasing greenhouse gas emissions are responsible for triggering a series of environmental imbalances that affect the Earth's complex climate dynamics. As a consequence of these changes, several climate models forecast an intensification of extreme weather events over the upcoming decades, including heat waves and increasingly severe drought and flood episodes. The occurrence of such extreme weather will prompt profound changes in several plant communities, resulting in massive forest dieback events that can trigger a massive loss of biodiversity in several biomes worldwide. Despite the gravity of the situation, our knowledge regarding how extreme weather events can undermine the performance, survival, and distribution of forest species remains very fragmented. Therefore, the present review aimed to provide a broad and integrated perspective of the main biochemical, physiological, and morpho-anatomical disorders that may compromise the performance and survival of forest species exposed to climate change factors, particularly drought, flooding, and global warming. In addition, we also discuss the controversial effects of high CO2 concentrations in enhancing plant growth and reducing the deleterious effects of some extreme climatic events. We conclude with a discussion about the possible effects that the factors associated with the climate change might have on species distribution and forest composition.
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Affiliation(s)
| | - Lucas Loram‐Lourenço
- Laboratory of Plant EcophysiologyInstituto Federal Goiano – Campus Rio VerdeGoiásBrazil
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18
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Smith MG, Arndt SK, Miller RE, Kasel S, Bennett LT. Trees use more non-structural carbohydrate reserves during epicormic than basal resprouting. Tree Physiol 2018; 38:1779-1791. [PMID: 30219862 DOI: 10.1093/treephys/tpy099] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 08/21/2018] [Indexed: 06/08/2023]
Abstract
Non-structural carbohydrates (NSCs) are crucial to support tree resprouting after disturbances that damage the crown or stem. Epicormic resprouting (from stem) could demand more from NSC reserves than basal resprouting (following top-kill), since epicormically resprouting trees need to maintain a greater living biomass. Yet, little is known about NSC use during epicormic resprouting, particularly the relative importance of stem and below-ground NSC reserves. We compared the distribution and magnitude of NSC decreases during epicormic and basal resprouting by experimentally removing crowns or stems of 14-year-old Eucalyptus obliqua L'Hér. trees in native forest, then harvesting these trees over a 10-month period (start, sprouts emerged, sprouts expanded) to measure changes in NSC concentration and mass by organ (stem, lignotuber, roots). We hypothesized that (i) NSC depletion during resprouting is primarily due to decreases in starch rather than soluble sugars concentrations; (ii) during epicormic resprouting, stem NSC concentrations are decreased irrespective of any decreases in roots; and (iii) absolute decreases in NSC mass are greater for epicormic than basal resprouting during the leafless period due to the carbon demands associated with maintaining greater living biomass. Results confirmed our hypotheses; starch was the primary storage carbohydrate, stems were an important source of starch during epicormic resprouting and carbon demands of maintenance functions were greater for epicormic resprouting, leading to greater decreases in NSC reserves. Roots were a more important starch storage organ than the lignotuber for both epicormic and basal resprouting. The proportional decrease in starch was severe for both modes of resprouting due to a long leafless period, after which trees resprouting epicormically relied on starch reserves for longer than those resprouting basally. It remains to be seen how the timing of disturbance affects the timing and vigour of resprouting, and how long-term NSC recovery differs for epicormic and basal resprouting.
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Affiliation(s)
- Merryn G Smith
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, Australia
| | - Stefan K Arndt
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, Australia
| | - Rebecca E Miller
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, Australia
| | - Sabine Kasel
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, Victoria, Australia
| | - Lauren T Bennett
- School of Ecosystem and Forest Sciences, The University of Melbourne, 4 Water Street, Creswick, Victoria, Australia
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19
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Refsland T, Fraterrigo J. Fire increases drought vulnerability of
Quercus alba
juveniles by altering forest microclimate and nitrogen availability. Funct Ecol 2018. [DOI: 10.1111/1365-2435.13193] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tyler Refsland
- Program in Ecology, Evolution and Conservation BiologyUniversity of Illinois Urbana Illinois
| | - Jennifer Fraterrigo
- Program in Ecology, Evolution and Conservation BiologyUniversity of Illinois Urbana Illinois
- Department of Natural Resources and Environmental SciencesUniversity of Illinois Urbana Illinois
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20
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Venturas MD, Sperry JS, Hacke UG. Plant xylem hydraulics: What we understand, current research, and future challenges. J Integr Plant Biol 2017; 59:356-389. [PMID: 28296168 DOI: 10.1111/jipb.12534] [Citation(s) in RCA: 159] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 03/09/2017] [Indexed: 05/22/2023]
Abstract
Herein we review the current state-of-the-art of plant hydraulics in the context of plant physiology, ecology, and evolution, focusing on current and future research opportunities. We explain the physics of water transport in plants and the limits of this transport system, highlighting the relationships between xylem structure and function. We describe the great variety of techniques existing for evaluating xylem resistance to cavitation. We address several methodological issues and their connection with current debates on conduit refilling and exponentially shaped vulnerability curves. We analyze the trade-offs existing between water transport safety and efficiency. We also stress how little information is available on molecular biology of cavitation and the potential role of aquaporins in conduit refilling. Finally, we draw attention to how plant hydraulic traits can be used for modeling stomatal responses to environmental variables and climate change, including drought mortality.
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Affiliation(s)
- Martin D Venturas
- Department of Biology, University of Utah, 257 S 1400E, Salt Lake City, UT, 84112, USA
| | - John S Sperry
- Department of Biology, University of Utah, 257 S 1400E, Salt Lake City, UT, 84112, USA
| | - Uwe G Hacke
- Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G 2E3, Canada
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21
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Pratt RB, Jacobsen AL. Conflicting demands on angiosperm xylem: Tradeoffs among storage, transport and biomechanics. Plant Cell Environ 2017; 40:897-913. [PMID: 27861981 DOI: 10.1111/pce.12862] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 10/31/2016] [Indexed: 05/26/2023]
Abstract
The secondary xylem of woody plants transports water mechanically supports the plant body and stores resources. These three functions are interdependent giving rise to tradeoffs in function. Understanding the relationships among these functions and their structural basis forms the context in which to interpret xylem evolution. The tradeoff between xylem transport efficiency and safety from cavitation has been carefully examined with less focus on other functions, particularly storage. Here, we synthesize data on all three xylem functions in angiosperm branch xylem in the context of tradeoffs. Species that have low safety and efficiency, examined from a resource economics perspective, are predicted to be adapted for slow resource acquisition and turnover as characterizes some environments. Tradeoffs with water storage primarily arise because of differences in fibre traits, while tradeoffs in carbohydrate storage are driven by parenchyma content of tissue. We find support for a tradeoff between safety from cavitation and storage of both water and starch in branch xylem tissue and between water storage capacity and mechanical strength. Living fibres may facilitate carbohydrate storage without compromising mechanical strength. The division of labour between different xylem cell types allows for considerable functional and structural diversity at multiple scales.
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Affiliation(s)
- R Brandon Pratt
- California State University, Bakersfield, Department of Biology, Bakersfield, CA, 93311, USA
| | - Anna L Jacobsen
- California State University, Bakersfield, Department of Biology, Bakersfield, CA, 93311, USA
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22
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Zhang WW, Song J, Wang M, Liu YY, Li N, Zhang YJ, Holbrook NM, Hao GY. Divergences in hydraulic architecture form an important basis for niche differentiation between diploid and polyploid Betula species in NE China. Tree Physiol 2017; 37:604-616. [PMID: 28338717 DOI: 10.1093/treephys/tpx004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 01/25/2017] [Indexed: 05/02/2023]
Abstract
Habitat differentiation between polyploid and diploid plants are frequently observed, with polyploids usually occupying more stressed environments. In woody plants, polyploidization can greatly affect wood characteristics but knowledge of its influences on xylem hydraulics is scarce. The four Betula species in NE China, representing two diploids and two polyploids with obvious habitat differentiation, provide an exceptional study system for investigating the impact of polyploidization on environmental adaptation of trees from the point view of xylem hydraulics. To test the hypothesis that changes in hydraulic architecture play an important role in determining their niche differentiation, we measured wood structural traits at both the tissue and pit levels and quantified xylem water transport efficiency and safety in these species. The two polyploids had significantly larger hydraulic weighted mean vessel diameters than the two diploids (45.1 and 45.5 vs 25.9 and 24.5 μm) although the polyploids are occupying more stressed environments. As indicated by more negative water potentials corresponding to 50% loss of stem hydraulic conductivities, the two polyploids exhibited significantly higher resistance to drought-induced embolism than the two diploids (-5.23 and -5.05 vs -3.86 and -3.13 MPa) despite their larger vessel diameters. This seeming discrepancy is reconciled by distinct characteristics favoring greater embolism resistance at the pit level in the two polyploid species. Our results showed clearly that the two polyploid species have remarkably different pit-level anatomical traits favoring greater hydraulic safety than their congeneric diploid species, which have likely contributed to the abundance of polyploid birches in more stressed habitats; however, less porous inter-conduit pits together with a reduced leaf to sapwood area may have compromised their competitiveness under more favorable conditions. Contrasts in hydraulic architecture between diploid and polyploid Betula species suggest an important functional basis for their clear habitat differentiation along environmental gradients in Changbai Mountain of NE China.
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Affiliation(s)
- Wei-Wei Zhang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, Liaoning, China
| | - Jia Song
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Miao Wang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, Liaoning, China
| | - Yan-Yan Liu
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Na Li
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, Liaoning, China
| | - Yong-Jiang Zhang
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - N Michele Holbrook
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- The Arnold Arboretum of Harvard University, Boston, MA 02131, USA
| | - Guang-You Hao
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, Liaoning, China
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23
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Parra A, Moreno JM. Post-fire environments are favourable for plant functioning of seeder and resprouter Mediterranean shrubs, even under drought. New Phytol 2017; 214:1118-1131. [PMID: 28240348 DOI: 10.1111/nph.14454] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 12/22/2016] [Indexed: 06/06/2023]
Abstract
Understanding how drought affects seeder and resprouter plants during post-fire regeneration is important for the anticipation of Mediterranean vegetation vulnerability in a context of increasing drought and fire caused by climate change. A Mediterranean shrubland was subjected to various drought treatments (including 45% rainfall reduction, 7 months drought yr-1 ), before and after experimental burning, by means of a rainout-shelter system with an irrigation facility. Predawn shoot water potential (Ψpd ), relative growth rate (RGR), specific leaf area (SLA) and bulk leaf carbon isotopic composition (δ13 C) were monitored in the main woody species during the first 3 yr after fire. Cistus ladanifer seedlings showed higher Ψpd , RGR and SLA, and lower δ13 C, than unburned plants during the first two post-fire years. Seedlings under drought maintained relatively high Ψpd , but suffered a decrease in Ψpd and RGR, and an increase in δ13 C, relative to control treatments. Erica arborea, E. scoparia and Phillyrea angustifolia resprouts had higher Ψpd and RGR than unburned plants during the first post-fire year. Resprouters were largely unaffected by drought. Overall, despite marked differences between the two functional groups, post-fire environments were favourable for plant functioning of both seeder and resprouter shrubs, even under the most severe drought conditions implemented.
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Affiliation(s)
- Antonio Parra
- Departamento de Ciencias Ambientales, Universidad de Castilla-La Mancha, Toledo, 45071, Spain
| | - José M Moreno
- Departamento de Ciencias Ambientales, Universidad de Castilla-La Mancha, Toledo, 45071, Spain
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