1
|
Blackman CJ, Halliwell B, Hartill GE, Brodribb TJ. Petiole XLA (xylem to leaf area ratio) integrates hydraulic safety and efficiency across a diverse group of eucalypt leaves. PLANT, CELL & ENVIRONMENT 2024; 47:49-58. [PMID: 37680088 DOI: 10.1111/pce.14713] [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: 03/14/2023] [Revised: 07/06/2023] [Accepted: 08/27/2023] [Indexed: 09/09/2023]
Abstract
A theoretical trade-off between the efficiency and safety of water transport systems in plants is used to explain diverse ecological patterns, from tree size to community structure. Despite its pervasive influence, this theory has marginal empirical support. This may be partially due to obfuscation of associations by wide phylogenetic sampling or non-standard sampling between studies. To address this, we examine the coordination of structural and anatomical traits linked to hydraulic safety and efficiency in the leaves of an ecologically diverse group of eucalypts. We introduce a new trait for characterising leaf water transport function measured as the cross-sectional XA at the petiole divided by the downstream leaf area (XLApetiole ). Variation in XLApetiole revealed support for a safety-efficiency trade-off in eucalypt leaves. XLApetiole was negatively correlated with theoretical petiole xylem conductivity (Ks_petiole ) and strongly negatively correlated with leaf cavitation vulnerability (Ψ50leaf ). Species with lower Ψ50leaf exhibited petiole xylem with narrower vessels and greater fibre wall area fractions. Our findings highlight XLApetiole as a novel integrative trait that provides insights into the evolution of leaf form and function in eucalypts and holds promise for wider use among diverse species.
Collapse
Affiliation(s)
- Chris J Blackman
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | - Ben Halliwell
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | - Gabrielle E Hartill
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | - Timothy J Brodribb
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia
| |
Collapse
|
2
|
Zhu LW, Zhao P. Climate-driven sapwood-specific hydraulic conductivity and the Huber value but not leaf-specific hydraulic conductivity on a global scale. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 857:159334. [PMID: 36220474 DOI: 10.1016/j.scitotenv.2022.159334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/27/2022] [Accepted: 10/06/2022] [Indexed: 06/16/2023]
Abstract
Efficient water transport is crucial for plant growth and survival. Plant hydraulic conductivity varies between functional groups and biomes and is strongly influenced by changing environmental conditions. However, correlations of conductivity-related hydraulic traits with climatic variables are not fully understood, preventing clarification of plant form and function under climate change scenarios. By compiling leaf-specific hydraulic conductivity (KL), sapwood-specific hydraulic conductivity (Ks), and Huber values (Hv, sapwood area to leaf area ratio) along with climatic variables including mean annual temperature (MAT), mean annual precipitation (MAP) and aridity index (AI) for 428 species across a wide range of plant functional types (PFTs) and biomes at a global scale, we found greater variability of KL within PFTs and biomes than across PFTs and biomes. Interaction effects between PFTs and biomes on KL and Ks were found. The interaction between MAT and MAP played a significant role in Ks and Hv (t = 3.89, P < 0.001 for Ks and t = -5.77, P < 0.001 for Hv). With increasing AI, Ks increased and Hv decreased. KL was not influenced by the investigated climatic variables. Our study provides a better understanding of the dynamics of hydraulic structure and function across functional groups and biomes and of the abiotic drivers of their large-scale variations.
Collapse
Affiliation(s)
- Li-Wei Zhu
- South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Ping Zhao
- South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
| |
Collapse
|
3
|
Staples TL, Mayfield MM, England JR, Dwyer JM. Drivers of Acacia and Eucalyptus growth rate differ in strength and direction in restoration plantings across Australia. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2636. [PMID: 35404495 PMCID: PMC9539508 DOI: 10.1002/eap.2636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 01/24/2022] [Accepted: 02/18/2022] [Indexed: 05/31/2023]
Abstract
Functional traits are proxies for a species' ecology and physiology and are often correlated with plant vital rates. As such they have the potential to guide species selection for restoration projects. However, predictive trait-based models often only explain a small proportion of plant performance, suggesting that commonly measured traits do not capture all important ecological differences between species. Some residual variation in vital rates may be evolutionarily conserved and captured using taxonomic groupings alongside common functional traits. We tested this hypothesis using growth rate data for 17,299 trees and shrubs from 80 species of Eucalyptus and 43 species of Acacia, two hyper-diverse and co-occurring genera, collected from 497 neighborhood plots in 137 Australian mixed-species revegetation plantings. We modeled relative growth rates of individual plants as a function of environmental conditions, species-mean functional traits, and neighbor density and diversity, across a moisture availability gradient. We then assessed whether the strength and direction of these relationships differed between the two genera. We found that the inclusion of genus-specific relationships offered a significant but modest improvement to model fit (1.6%-1.7% greater R2 than simpler models). More importantly, almost all correlates of growth rate differed between Eucalyptus and Acacia in strength, direction, or how they changed along the moisture gradient. These differences mapped onto physiological differences between the genera that were not captured solely by measured functional traits. Our findings suggest taxonomic groupings can capture or mediate variation in plant performance missed by common functional traits. The inclusion of taxonomy can provide a more nuanced understanding of how functional traits interact with abiotic and biotic conditions to drive plant performance, which may be important for constructing trait-based frameworks to improve restoration outcomes.
Collapse
Affiliation(s)
- Timothy L. Staples
- School of Biological SciencesThe University of QueenslandBrisbaneQueenslandAustralia
- CSIRO Land and Water, EcoSciences PrecinctDutton ParkQueenslandAustralia
| | - Margaret M. Mayfield
- School of Biological SciencesThe University of QueenslandBrisbaneQueenslandAustralia
| | | | - John M. Dwyer
- School of Biological SciencesThe University of QueenslandBrisbaneQueenslandAustralia
- CSIRO Land and Water, EcoSciences PrecinctDutton ParkQueenslandAustralia
| |
Collapse
|
4
|
Whole-Plant Water Use and Hydraulics of Populus euphratica and Tamarix ramosissima Seedlings in Adaption to Groundwater Variation. WATER 2022. [DOI: 10.3390/w14121869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Riparian phreatophytes in hyperarid areas face selection pressure from limiting groundwater availability and high transpiration demand. We examined whole-plant water use and hydraulic traits in Populus euphratica and Tamarix ramosissima seedlings to understand how they adapt to groundwater variations. These species coexist in the Tarim River floodplain of western China. Measurements were performed on 3-year-old seedlings grown in lysimeters simulating various groundwater depths. P. euphratica had relatively greater leaf area-specific water use due to its comparatively higher sapwood area to leaf area ratio (Hv). A high Hv indicates that its sapwood has a limited capacity to support its leaf area. P. euphratica also showed significantly higher leaf-specific conductivity (ksl) than T. ramosissima but both had similar sapwood-specific conductivities (kss). Therefore, it was Hv rather than kss which accounted for the interspecific difference in ksl. When groundwater was not directly available, ksl and Hv in P. euphratica were increased. This response favors water loss control, but limits plant growth. In contrast, T. ramosissima is more capable of using deep groundwater. Stomatal sensitivity to increasing leaf-to-area vapor pressure deficit was also higher in P. euphratica. Overall, P. euphratica is less effective than T. ramosissima at compensating for transpirational water loss at a whole-plant level. For this reason, P. euphratica is restricted to riverbanks, whereas T. ramosissima occurs over a wide range of groundwater depths.
Collapse
|
5
|
Arend M, Link RM, Zahnd C, Hoch G, Schuldt B, Kahmen A. Lack of hydraulic recovery as a cause of post-drought foliage reduction and canopy decline in European beech. THE NEW PHYTOLOGIST 2022; 234:1195-1205. [PMID: 35238410 PMCID: PMC9310744 DOI: 10.1111/nph.18065] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 02/19/2022] [Indexed: 05/06/2023]
Abstract
European beech (Fagus sylvatica) was among the most affected tree species during the severe 2018 European drought. It not only suffered from instant physiological stress but also showed severe symptoms of defoliation and canopy decline in the following year. To explore the underlying mechanisms, we used the Swiss-Canopy-Crane II site and studied in branches of healthy and symptomatic trees the repair of hydraulic function and concentration of carbohydrates during the 2018 drought and in 2019. We found loss of hydraulic conductance in 2018, which did not recover in 2019 in trees that developed defoliation symptoms in the year after drought. Reduced branch foliation in symptomatic trees was associated with a gradual decline in wood starch concentration throughout summer 2019. Visualization of water transport in healthy and symptomatic branches in the year after the drought confirmed the close relationship between xylem functionality and supported branch leaf area. Our findings showed that embolized xylem does not regain function in the season following a drought and that sustained branch hydraulic dysfunction is counterbalanced by the reduction in supported leaf area. It suggests acclimation of leaf development after drought to mitigate disturbances in canopy hydraulic function.
Collapse
Affiliation(s)
- Matthias Arend
- Physiological Plant EcologyUniversity of Basel4056BaselSwitzerland
| | - Roman Mathias Link
- Ecophysiology and Vegetation EcologyUniversität Würzburg97082WürzburgGermany
| | - Cedric Zahnd
- Physiological Plant EcologyUniversity of Basel4056BaselSwitzerland
| | - Günter Hoch
- Physiological Plant EcologyUniversity of Basel4056BaselSwitzerland
| | - Bernhard Schuldt
- Ecophysiology and Vegetation EcologyUniversität Würzburg97082WürzburgGermany
| | - Ansgar Kahmen
- Physiological Plant EcologyUniversity of Basel4056BaselSwitzerland
| |
Collapse
|
6
|
Peters JMR, López R, Nolf M, Hutley LB, Wardlaw T, Cernusak LA, Choat B. Living on the edge: A continental-scale assessment of forest vulnerability to drought. GLOBAL CHANGE BIOLOGY 2021; 27:3620-3641. [PMID: 33852767 DOI: 10.1111/gcb.15641] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/12/2021] [Indexed: 06/12/2023]
Abstract
Globally, forests are facing an increasing risk of mass tree mortality events associated with extreme droughts and higher temperatures. Hydraulic dysfunction is considered a key mechanism of drought-triggered dieback. By leveraging the climate breadth of the Australian landscape and a national network of research sites (Terrestrial Ecosystem Research Network), we conducted a continental-scale study of physiological and hydraulic traits of 33 native tree species from contrasting environments to disentangle the complexities of plant response to drought across communities. We found strong relationships between key plant hydraulic traits and site aridity. Leaf turgor loss point and xylem embolism resistance were correlated with minimum water potential experienced by each species. Across the data set, there was a strong coordination between hydraulic traits, including those linked to hydraulic safety, stomatal regulation and the cost of carbon investment into woody tissue. These results illustrate that aridity has acted as a strong selective pressure, shaping hydraulic traits of tree species across the Australian landscape. Hydraulic safety margins were constrained across sites, with species from wetter sites tending to have smaller safety margin compared with species at drier sites, suggesting trees are operating close to their hydraulic thresholds and forest biomes across the spectrum may be susceptible to shifts in climate that result in the intensification of drought.
Collapse
Affiliation(s)
- Jennifer M R Peters
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Rosana López
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Markus Nolf
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Lindsay B Hutley
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT, Australia
| | - Tim Wardlaw
- ARC Centre for Forest Value, University of Tasmania, Hobart, Tas, Australia
| | - Lucas A Cernusak
- College of Science and Engineering, James Cook University, Cairns, Qld, Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| |
Collapse
|
7
|
Westerhuis EL, Nano CE, Morton SR, Christian KA, Schlesinger CA. Stability and predictability of bird assemblages in an arid riparian woodland during contrasting periods of resource availability. AUSTRAL ECOL 2020. [DOI: 10.1111/aec.12933] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Erin L. Westerhuis
- Research Institute for the Environment and Livelihoods; Charles Darwin University; Alice Springs Northern Territory 0870 Australia
| | - Catherine E.M. Nano
- Flora and Fauna Division; Department of Environment and Natural Resources; Northern Territory Government; Alice Springs Northern Territory Australia
| | - Stephen R. Morton
- Research Institute for the Environment and Livelihoods; Charles Darwin University; Alice Springs Northern Territory 0870 Australia
| | - Keith A. Christian
- Research Institute for the Environment and Livelihoods; Charles Darwin University; Casuarina Northern Territory Australia
| | - Christine A. Schlesinger
- Research Institute for the Environment and Livelihoods; Charles Darwin University; Alice Springs Northern Territory 0870 Australia
| |
Collapse
|
8
|
Tarin T, Nolan RH, Medlyn BE, Cleverly J, Eamus D. Water-use efficiency in a semi-arid woodland with high rainfall variability. GLOBAL CHANGE BIOLOGY 2020; 26:496-508. [PMID: 31597216 DOI: 10.1111/gcb.14866] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 08/30/2019] [Accepted: 10/03/2019] [Indexed: 06/10/2023]
Abstract
As the ratio of carbon uptake to water use by vegetation, water-use efficiency (WUE) is a key ecosystem property linking global carbon and water cycles. It can be estimated in several ways, but it is currently unclear how different measures of WUE relate, and how well they each capture variation in WUE with soil moisture availability. We evaluated WUE in an Acacia-dominated woodland ecosystem of central Australia at various spatial and temporal scales using stable carbon isotope analysis, leaf gas exchange and eddy covariance (EC) fluxes. Semi-arid Australia has a highly variable rainfall pattern, making it an ideal system to study how WUE varies with water availability. We normalized our measures of WUE across a range of vapour pressure deficits using g1 , which is a parameter derived from an optimal stomatal conductance model and which is inversely related to WUE. Continuous measures of whole-ecosystem g1 obtained from EC data were elevated in the 3 days following rain, indicating a strong effect of soil evaporation. Once these values were removed, a close relationship of g1 with soil moisture content was observed. Leaf-scale values of g1 derived from gas exchange were in close agreement with ecosystem-scale values. In contrast, values of g1 obtained from stable isotopes did not vary with soil moisture availability, potentially indicating remobilization of stored carbon during dry periods. Our comprehensive comparison of alternative measures of WUE shows the importance of stomatal control of fluxes in this highly variable rainfall climate and demonstrates the ability of these different measures to quantify this effect. Our study provides the empirical evidence required to better predict the dynamic carbon-water relations in semi-arid Australian ecosystems.
Collapse
Affiliation(s)
- Tonantzin Tarin
- Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, Sydney, NSW, Australia
- Department of Soil and Plant Sciences, University of Delaware, Newark, DE, USA
| | - Rachael H Nolan
- Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, Sydney, NSW, Australia
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Belinda E Medlyn
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - James Cleverly
- Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, Sydney, NSW, Australia
- Terrestrial Ecosystem Research Network (TERN), University of Technology, Sydney, NSW, Australia
| | - Derek Eamus
- Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, Sydney, NSW, Australia
| |
Collapse
|
9
|
Brodersen CR, Roddy AB, Wason JW, McElrone AJ. Functional Status of Xylem Through Time. ANNUAL REVIEW OF PLANT BIOLOGY 2019; 70:407-433. [PMID: 30822114 DOI: 10.1146/annurev-arplant-050718-100455] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Water transport in vascular plants represents a critical component of terrestrial water cycles and supplies the water needed for the exchange of CO2 in the atmosphere for photosynthesis. Yet, many fundamental principles of water transport are difficult to assess given the scale and location of plant xylem. Here we review the mechanistic principles that underpin long-distance water transport in vascular plants, with a focus on woody species. We also discuss the recent development of noninvasive tools to study the functional status of xylem networks in planta. Limitations of current methods to detect drought-induced xylem blockages (e.g., embolisms) and quantify corresponding declines in sap flow, and the coordination of hydraulic dysfunction with other physiological processes are assessed. Future avenues of research focused on cross-validation of plant hydraulics methods are discussed, as well as a proposed fundamental shift in the theory and methodology used to characterize and measure plant water use.
Collapse
Affiliation(s)
- Craig R Brodersen
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA;
| | - Adam B Roddy
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA;
| | - Jay W Wason
- School of Forest Resources, University of Maine, Orono, Maine 04469, USA
| | - Andrew J McElrone
- US Department of Agriculture, Agricultural Research Service, Davis, California 95616, USA
- Department of Viticulture and Enology, University of California, Davis, California 95616, USA
| |
Collapse
|
10
|
Yu T, Feng Q, Si J, Xi H, O'Grady AP, Pinkard EA. Responses of riparian forests to flood irrigation in the hyper-arid zone of NW China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 648:1421-1430. [PMID: 30340287 DOI: 10.1016/j.scitotenv.2018.08.287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 08/21/2018] [Accepted: 08/21/2018] [Indexed: 06/08/2023]
Abstract
Knowledge of forest water use is crucial to water resources managers, especially in arid environments. Flood irrigation has sometimes been used to ameliorate forest decline, however, there has only been limited research on vegetation responses to these interventions. We undertook a study to quantify evapotranspiration (ET) and its components, transpiration (T) and evaporation (E), of two Populus euphratica Oliv. stands (MA: middle-aged and OA: old-aged) with and without flood irrigation in the lower Heihe River Basin of NW China. ET and T were measured using eddy covariance and sap flow methods, respectively. Understory E was estimated by difference. Annual ET was 766.4 mm in the MA stand and 532.5 mm in the OA stand with an average of 4.2 and 2.9 mm d-1 during the growing season, respectively. ET of the MA stand was 44% higher than that of the OA stand, with contributions of 28% and 16% from E and T. Despite stand density, leaf area index and canopy cover being higher in the MA than OA stand sapwood area within the two stands was similar (MA 6.04 m2 ha-1 and OA 6.02 m2 ha-1). We hypothesised lower understory E and a lower E to ET ratio in the MA stand than OA stand. However, E was approximately 63% of ET in both stands. Therefore, we conclude that differences in ET, T and E were mainly associated with the flood irrigation. This was further supported by the comparable ET between the OA stand and the other studies in arid regions of Central Asia. In conclusion, flood irrigation has a less significant effect on canopy water use (T) than understory E suggesting alternatives to flood irrigation might be more appropriate in this water-limited ecosystem.
Collapse
Affiliation(s)
- Tengfei Yu
- Alax Desert Eco-Hydrology Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Key Laboratory of Eco-Hydrology of Inland River Basin, Chinese Academy of Sciences, Lanzhou 730000, China; Gansu Hydrology and Water Resources Engineering Research Center, Lanzhou 730000, China.
| | - Qi Feng
- Alax Desert Eco-Hydrology Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Key Laboratory of Eco-Hydrology of Inland River Basin, Chinese Academy of Sciences, Lanzhou 730000, China; Gansu Hydrology and Water Resources Engineering Research Center, Lanzhou 730000, China
| | - Jianhua Si
- Alax Desert Eco-Hydrology Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Key Laboratory of Eco-Hydrology of Inland River Basin, Chinese Academy of Sciences, Lanzhou 730000, China; Gansu Hydrology and Water Resources Engineering Research Center, Lanzhou 730000, China
| | - Haiyang Xi
- Alax Desert Eco-Hydrology Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Key Laboratory of Eco-Hydrology of Inland River Basin, Chinese Academy of Sciences, Lanzhou 730000, China; Gansu Hydrology and Water Resources Engineering Research Center, Lanzhou 730000, China
| | - Anthony P O'Grady
- CSIRO Land and Water, 15 College Rd, Sandy Bay, Hobart 7005, Australia
| | | |
Collapse
|
11
|
Miyazawa Y, Du S, Taniguchi T, Yamanaka N, Kumagai T. Gas exchange by the mesic-origin, arid land plantation species Robinia pseudoacacia under annual summer reduction in plant hydraulic conductance. TREE PHYSIOLOGY 2018; 38:1166-1179. [PMID: 29608763 DOI: 10.1093/treephys/tpy032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 03/06/2018] [Indexed: 06/08/2023]
Abstract
The mesic-origin plantation species Robinia pseudoacacia L. has been successfully grown in many arid land plantations around the world but often exhibits dieback and reduced growth due to drought. Therefore, to explore the behavior of this species under changing environmental conditions, we examined the relationship between ecophysiological traits, gas exchange and plant hydraulics over a 3-year period in trees that experienced reduced plant hydraulic conductance (Gp) in summer. We found that the transpiration rate, stomatal conductance (Gs) and minimum leaf water potential (Ψlmin) decreased in early summer in response to a decrease in Gp, and that Gp did not recover until the expansion of new leaves in spring. However, we did not observe any changes in the leaf area index or other ecophysiological traits at the leaf level in response to this reduction in Gp. Furthermore, model simulations based on measured data revealed that the canopy-scale photosynthetic rate (Ac) was 15-25% higher than the simulated Ac when it was assumed that Ψlmin remained constant after spring but almost the same as the simulated Ac when it was assumed that Gp remained high even after spring. These findings indicate that R. pseudoacacia was frequently exposed to a reduced Gp at the study site but offset its effects on Ac by plastically lowering Ψlmin to avoid experiencing any further reduction in Gp or Gs.
Collapse
Affiliation(s)
- Yoshiyuki Miyazawa
- Department of Geography, University of Hawai'i at Manoa, Honolulu, HI, USA
- Research Institute for East Asian Environments, Kyushu University, 744 Motooka, Fukuoka, Japan
| | - Sheng Du
- State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi, China
| | - Takeshi Taniguchi
- Aridland Research Center, Tottori University, Hamasaka, Tottori, Japan
| | - Norikazu Yamanaka
- Aridland Research Center, Tottori University, Hamasaka, Tottori, Japan
| | - Tomo'omi Kumagai
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan
| |
Collapse
|
12
|
Nolan RH, Tarin T, Santini NS, McAdam SAM, Ruman R, Eamus D. Differences in osmotic adjustment, foliar abscisic acid dynamics, and stomatal regulation between an isohydric and anisohydric woody angiosperm during drought. PLANT, CELL & ENVIRONMENT 2017; 40:3122-3134. [PMID: 28982212 DOI: 10.1111/pce.13077] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 09/18/2017] [Accepted: 09/20/2017] [Indexed: 06/07/2023]
Abstract
Species are often classified along a continuum from isohydric to anisohydric, with isohydric species exhibiting tighter regulation of leaf water potential through stomatal closure in response to drought. We investigated plasticity in stomatal regulation in an isohydric (Eucalyptus camaldulensis) and an anisohydric (Acacia aptaneura) angiosperm species subject to repeated drying cycles. We also assessed foliar abscisic acid (ABA) content dynamics, aboveground/belowground biomass allocation and nonstructural carbohydrates. The anisohydric species exhibited large plasticity in the turgor loss point (ΨTLP ), with plants subject to repeated drying exhibiting lower ΨTLP and correspondingly larger stomatal conductance at low water potential, compared to plants not previously exposed to drought. The anisohydric species exhibited a switch from ABA to water potential-driven stomatal closure during drought, a response previously only reported for anisohydric gymnosperms. The isohydric species showed little osmotic adjustment, with no evidence of switching to water potential-driven stomatal closure, but did exhibit increased root:shoot ratios. There were no differences in carbohydrate depletion between species. We conclude that a large range in ΨTLP and biphasic ABA dynamics are indicative of anisohydric species, and these traits are associated with exposure to low minimum foliar water potential, dense sapwood and large resistance to xylem embolism.
Collapse
Affiliation(s)
- Rachael H Nolan
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Ultimo, New South Wales, 2007, Australia
| | - Tonantzin Tarin
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Ultimo, New South Wales, 2007, Australia
| | - Nadia S Santini
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Ultimo, New South Wales, 2007, Australia
- Institute of Ecology, National Autonomous University of Mexico, External Circuit S/N annex Botanical Garden exterior, University City, Mexico City, 04500, Mexico
| | - Scott A M McAdam
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, 7001, Australia
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA
| | - Rizwana Ruman
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Ultimo, New South Wales, 2007, Australia
| | - Derek Eamus
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Ultimo, New South Wales, 2007, Australia
| |
Collapse
|
13
|
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.
Collapse
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
| |
Collapse
|
14
|
Nolan RH, Tarin T, Fairweather KA, Cleverly J, Eamus D. Variation in photosynthetic traits related to access to water in semiarid Australian woody species. FUNCTIONAL PLANT BIOLOGY : FPB 2017; 44:1087-1097. [PMID: 32480635 DOI: 10.1071/fp17096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 07/11/2017] [Indexed: 06/11/2023]
Abstract
Low soil water content can limit photosynthesis by reducing stomatal conductance. Here, we explore relationships among traits pertaining to carbon uptake and pre-dawn leaf water potential (as an index of soil water availability) across eight species found in semiarid central Australia. We found that as pre-dawn leaf water potential declined, stomatal limitations to photosynthesis increased, as did foliar nitrogen, which enhanced photosynthesis. Nitrogen-fixing Acacia species had higher foliar nitrogen concentrations compared with non-nitrogen fixing species, although there was considerable variability of traits within the Acacia genus. From principal component analysis we found that the most dissimilar species was Acacia aptaneura Maslin&J.E.Reid compared with both Eucalyptus camaldulensis Dehnh. and Corymbia opaca. (D.J.Carr & S.G.M.Carr)K.D.Hill&L.A.S.Johnson, having both the largest foliar N content, equal largest leaf mass per area and experiencing the lowest pre-dawn water potential of all species. A. aptaneura has shallow roots and grows above a hardpan that excludes access to groundwater, in contrast to E. camaldulensis and C. opaca, which are known to access groundwater. We conclude that ecohydrological niche separation is an important factor driving the variability of within-biome traits related to carbon gain. These observations have important implications for global vegetation models, which are parameterised with many of the traits measured here, but are often limited by data availability.
Collapse
Affiliation(s)
- Rachael H Nolan
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia
| | - Tonantzin Tarin
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia
| | - Kendal A Fairweather
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia
| | - James Cleverly
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia
| | - Derek Eamus
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia
| |
Collapse
|
15
|
Funk JL, Larson JE, Ames GM, Butterfield BJ, Cavender‐Bares J, Firn J, Laughlin DC, Sutton‐Grier AE, Williams L, Wright J. Revisiting the
H
oly
G
rail: using plant functional traits to understand ecological processes. Biol Rev Camb Philos Soc 2016; 92:1156-1173. [DOI: 10.1111/brv.12275] [Citation(s) in RCA: 389] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 03/14/2016] [Accepted: 03/17/2016] [Indexed: 12/14/2022]
Affiliation(s)
- Jennifer L. Funk
- Schmid College of Science and Technology, Chapman University 1 University Drive Orange CA 92866 USA
| | - Julie E. Larson
- Schmid College of Science and Technology, Chapman University 1 University Drive Orange CA 92866 USA
| | - Gregory M. Ames
- Department of Biology Duke University Box 90338 Durham NC 27708 USA
| | - Bradley J. Butterfield
- Merriam‐Powell Center for Environmental Research and Department of Biological Sciences Northern Arizona University Box 5640 Flagstaff AZ 86011 USA
| | - Jeannine Cavender‐Bares
- Department of Ecology, Evolution and Behavior University of Minnesota 1475 Gortner Avenue St. Paul MN 55108 USA
| | - Jennifer Firn
- School of Earth, Environmental and Biological Sciences, Queensland University of Technology Gardens Point Brisbane Queensland 4000 Australia
| | - Daniel C. Laughlin
- Environmental Research Institute and School of Science University of Waikato Private Bag 3105 Hamilton 3240 New Zealand
| | - Ariana E. Sutton‐Grier
- National Ocean Service National Oceanic and Atmospheric Administration 1305 East‐West Highway Silver Spring MD 20910 USA
- Earth System Science Interdisciplinary Center University of Maryland 5825 University Research Ct #4001 College Park MD 20740 USA
| | - Laura Williams
- Department of Ecology, Evolution and Behavior University of Minnesota 1475 Gortner Avenue St. Paul MN 55108 USA
| | - Justin Wright
- Department of Biology Duke University Box 90338 Durham NC 27708 USA
| |
Collapse
|
16
|
Modelling Seasonal and Inter-annual Variations in Carbon and Water Fluxes in an Arid-Zone Acacia Savanna Woodland, 1981–2012. Ecosystems 2016. [DOI: 10.1007/s10021-015-9956-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
17
|
Elkin C, Giuggiola A, Rigling A, Bugmann H. Short- and long-term efficacy of forest thinning to mitigate drought impacts in mountain forests in the European Alps. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2015; 25:1083-1098. [PMID: 26465044 DOI: 10.1890/14-0690.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In many regions of the world, drought is projected to increase under climate change, with potential negative consequences for forests and their ecosystem services (ES). Forest thinning has been proposed as a method for at least temporarily mitigating drought impacts, but its general applicability and longer-term impacts are unclear. We use a process-based forest model to upscale experimental data for evaluating the impacts of forest thinning in a drought-susceptible valley in the interior of the European Alps, with the specific aim of assessing (1) when and where thinning may be most effective and (2) the longer-term implications for forest dynamics. Simulations indicate that forests will be impacted by climate-induced increases in drought across a broad elevation range. At lower elevations, where drought is currently prevalent, thinning is projected to temporarily reduce tree mortality, but to have minor impacts on forest dynamics in the longer term. Thinning may be particularly useful at intermediate and higher elevations as a means of temporarily reducing mortality in drought-sensitive species such as Norway spruce and larch, which currently dominate these elevations. However, in the longer term, even intense thinning will likely not be sufficient to prevent a climate change induced dieback of these species, which is projected to occur under even moderate climate change. Thinning is also projected to have the largest impact on long-term forest dynamics at intermediate elevations, with the magnitude of the impact depending on the timing and intensity of thinning. More intense thinning that is done later is projected to more strongly promote a transition to more drought-tolerant species. We conclude that thinning is a viable option for temporarily reducing the negative drought impacts on forests, but that efficient implementation of thinning should be contingent on a site-specific evaluation of the near term risk of significant drought, and how thinning will impact the rate and direction of climate driven forest conversion.
Collapse
|
18
|
Givnish TJ, Wong SC, Stuart-Williams H, Holloway-Phillips M, Farquhar GD. Determinants of maximum tree height inEucalyptusspecies along a rainfall gradient in Victoria, Australia. Ecology 2014. [DOI: 10.1890/14-0240.1] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
19
|
Johnstone D, Tausz M, Moore G, Nicolas M. Bark and leaf chlorophyll fluorescence are linked to wood structural changes in Eucalyptus saligna. AOB PLANTS 2014; 6:plt057. [PMID: 24790120 PMCID: PMC3922302 DOI: 10.1093/aobpla/plt057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2013] [Accepted: 12/09/2013] [Indexed: 06/03/2023]
Abstract
Wood structure and wood anatomy are usually considered to be largely independent of the physiological processes that govern tree growth. This paper reports a statistical relationship between leaf and bark chlorophyll fluorescence and wood density. A relationship between leaf and bark chlorophyll fluorescence and the quantity of wood decay in a tree is also described. There was a statistically significant relationship between the leaf chlorophyll fluorescence parameter Fv/Fm and wood density and the quantity of wood decay in summer, but not in spring or autumn. Leaf chlorophyll fluorescence at 0.05 ms (the O step) could predict the quantity of wood decay in trees in spring. Bark chlorophyll fluorescence could predict wood density in spring using the Fv/Fm parameter, but not in summer or autumn. There was a consistent statistical relationship in spring, summer and autumn between the bark chlorophyll fluorescence parameter Fv/Fm and wood decay. This study indicates a relationship between chlorophyll fluorescence and wood structural changes, particularly with bark chlorenchyma.
Collapse
Affiliation(s)
- Denise Johnstone
- Department of Resource Management and Geography, University of Melbourne, Burnley Campus, Richmond 3012, Australia
| | - Michael Tausz
- Department of Forest and Ecosystem Science, University of Melbourne, Creswick Campus, Creswick 3363, Australia
| | - Gregory Moore
- Department of Resource Management and Geography, University of Melbourne, Burnley Campus, Richmond 3012, Australia
| | - Marc Nicolas
- Department of Agriculture and Food Systems, University of Melbourne, Parkville Campus, Parkville 3010, Australia
| |
Collapse
|
20
|
Liu F, Archer SR, Gelwick F, Bai E, Boutton TW, Wu XB. Woody plant encroachment into grasslands: spatial patterns of functional group distribution and community development. PLoS One 2013; 8:e84364. [PMID: 24367655 PMCID: PMC3867480 DOI: 10.1371/journal.pone.0084364] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 11/21/2013] [Indexed: 11/18/2022] Open
Abstract
Woody plant encroachment into grasslands has been globally widespread. The woody species invading grasslands represent a variety of contrasting plant functional groups and growth forms. Are some woody plant functional types (PFTs) better suited to invade grasslands than others? To what extent do local patterns of distribution and abundance of woody PFTs invading grasslands reflect intrinsic topoedaphic properties versus plant-induced changes in soil properties? We addressed these questions in the Southern Great Plains, United States at a subtropical grassland known to have been encroached upon by woody species over the past 50-100 years. A total of 20 woody species (9 tree-statured; 11 shrub-statured) were encountered along a transect extending from an upland into a playa basin. About half of the encroaching woody plants were potential N2-fixers (55% of species), but they contributed only 7% to 16 % of the total basal area. Most species and the PFTs they represent were ubiquitously distributed along the topoedaphic gradient, but with varying abundances. Overstory-understory comparisons suggest that while future species composition of these woody communities is likely to change, PFT composition is not. Canonical correspondence analysis (CCA) ordination and variance partitioning (Partial CCA) indicated that woody species and PFT composition in developing woody communities was primarily influenced by intrinsic landscape location variables (e.g., soil texture) and secondarily by plant-induced changes in soil organic carbon and total nitrogen content. The ubiquitous distribution of species and PFTs suggests that woody plants are generally well-suited to a broad range of grassland topoedaphic settings. However, here we only examined categorical and non-quantitative functional traits. Although intrinsic soil properties exerted more control over the floristics of grassland-to-woodland succession did plant modifications of soil carbon and nitrogen concentrations, the latter are likely to influence productivity and nutrient cycling and may, over longer time-frames, feed back to influence PFT distributions.
Collapse
Affiliation(s)
- Feng Liu
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
- Department of Ecosystem Science and Management, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
| | - Steven R. Archer
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, United States of America
| | - Frances Gelwick
- Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Edith Bai
- State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
| | - Thomas W. Boutton
- Department of Ecosystem Science and Management, Texas A&M University, College Station, Texas, United States of America
| | - Xinyuan Ben Wu
- Department of Ecosystem Science and Management, Texas A&M University, College Station, Texas, United States of America
| |
Collapse
|
21
|
Johnstone D, Moore G, Tausz M, Nicolas M. The measurement of plant vitality in landscape trees. ACTA ACUST UNITED AC 2013. [DOI: 10.1080/03071375.2013.783746] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
22
|
Vandegehuchte MW, Steppe K. Improving sap flux density measurements by correctly determining thermal diffusivity, differentiating between bound and unbound water. TREE PHYSIOLOGY 2012; 32:930-942. [PMID: 22543477 DOI: 10.1093/treephys/tps034] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Several heat-based sap flow methods, such as the heat field deformation method and the heat ratio method, include the thermal diffusivity D of the sapwood as a crucial parameter. Despite its importance, little attention has been paid to determine D in a plant physiological context. Therefore, D is mostly set as a constant, calculated during zero flow conditions or from a method of mixtures, taking into account wood density and moisture content. In this latter method, however, the meaning of the moisture content is misinterpreted, making it theoretically incorrect for D calculations in sapwood. A correction to this method, which includes the correct application of the moisture content, is proposed. This correction was tested for European and American beech and Eucalyptus caliginosa Blakely & McKie. Depending on the dry wood density and moisture content, the original approach over- or underestimates D and, hence, sap flux density by 10% and more.
Collapse
Affiliation(s)
- Maurits W Vandegehuchte
- Laboratory of Plant Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Gent, Belgium.
| | | |
Collapse
|
23
|
Page GFM, Liu J, Grierson PF. Three-dimensional xylem networks and phyllode properties of co-occurring Acacia. PLANT, CELL & ENVIRONMENT 2011; 34:2149-2158. [PMID: 21848859 DOI: 10.1111/j.1365-3040.2011.02411.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Reduced leaf size is often correlated to increased aridity, where smaller leaves demand less water via xylem conduits. However, it is unknown if differences in three-dimensional (3D) xylem connectivity reflect leaf-level adaptations. We used X-ray microtomography (micro-CT) to quantify 3D xylem connectivity in ∼5 mm diameter branch sections of co-occurring semi-arid Acacia species of varied phyllode size. We compared 3D connectivity to minimum branch water potential and two-dimensional (2D) vessel attributes derived from sections produced by micro-CT. 2D attributes included vessel area, density, vessel size to number ratio (S) and vessel lumen fraction (F). Trees with terete phyllodes had less negative water potentials than broad phyllode variants. 3D xylem connectivity was conserved across all trees regardless of phyllode type or minimum water potential. We also found that xylem connectivity was sensitive to vessel lumen fraction (F) and not the size to number ratio (S) even though F was consistent among species and phyllode variants. Our results demonstrate that differences in phyllode anatomy, and not xylem connectivity, likely explain diversity of drought tolerance among closely related Acacia species. Further analysis using our approach across a broader range of species will improve understanding of adaptations in the xylem networks of arid zone species.
Collapse
Affiliation(s)
- Gerald F M Page
- Ecosystems Research Group, School of Plant Biology, The University of Western Australia, Crawley, WA 6009, Australia
| | | | | |
Collapse
|
24
|
Pfautsch S, Keitel C, Turnbull TL, Braimbridge MJ, Wright TE, Simpson RR, O'Brien JA, Adams MA. Diurnal patterns of water use in Eucalyptus victrix indicate pronounced desiccation-rehydration cycles despite unlimited water supply. TREE PHYSIOLOGY 2011; 31:1041-1051. [PMID: 21908853 DOI: 10.1093/treephys/tpr082] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Knowledge about nocturnal transpiration (E(night)) of trees is increasing and its impact on regional water and carbon balance has been recognized. Most of this knowledge has been generated in temperate or equatorial regions. Yet, little is known about E(night) and tree water use (Q) in semi-arid regions. We investigated the influence of atmospheric conditions on daytime (Q(day)) and nighttime water transport (Q(night)) of Eucalyptus victrix L.A.S. Johnson & K.D. Hill growing over shallow groundwater (not >1.5 m in depth) in semi-arid tropical Australia. We recorded Q(day) and Q(night) at different tree heights in conjunction with measurements of stomatal conductance (g(s)) and partitioned E(night) from refilling processes. Q of average-sized trees (200-400 mm diameter) was 1000-3000 l month(-1), but increased exponentially with diameter such that large trees (>500 mm diameter) used up to 8000 l month(-1). Q was remarkably stable across seasons. Water flux densities (J(s)) varied significantly at different tree heights during day and night. We show that g(s) remained significantly different from zero and E(night) was always greater than zero due to vapor pressure deficits (D) that remained >1.5 kPa at night throughout the year. Q(night) reached a maximum of 50% of Q(day) and was >0.03 mm h(-1) averaged across seasons. Refilling began during afternoon hours and continued well into the night. Q(night) eventually stabilized and closely tracked D(night). Coupling of Q(night) and D(night) was particularly strong during the wet season (R2 = 0.95). We suggest that these trees have developed the capacity to withstand a pronounced desiccation-rehydration cycle in a semi-arid environment. Such a cycle has important implications for local and regional hydrological budgets of semi-arid landscapes, as large nighttime water fluxes must be included in any accounting.
Collapse
Affiliation(s)
- Sebastian Pfautsch
- Faculty of Agriculture, Food and Natural Resources, University of Sydney, 1 Central Avenue, Eveleigh, NSW 2015, Australia.
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Abstract
Forest canopies exchange a large part of the mass and energy between the earth and the atmosphere. The processes that regulate these exchanges have been of interest to scientists from a diverse range of disciplines for a long time. The International Union of Forest Research Organizations (IUFRO) Canopy Processes Working Group provides a forum for these scientists to explore canopy processes at scales ranging from the leaf to the ecosystem. Given the changes in climate that are being experienced in response to rising [CO(2)], there is a need to understand how forest canopy processes respond to altered environments. Globally, native and managed forests represent the largest terrestrial biome and, in wood and soils, the largest terrestrial stores of carbon. Changing climates have significant implications for carbon storage in forests, as well as their water use, species diversity and management. In order to address these issues, the Canopy Processes Working Group held a travelling workshop in south-east Australia during October 2010 to examine the impact of changing climates on forest canopies, highlighting knowledge gaps and developing new research directions.
Collapse
|
26
|
Fan DY, Jie SL, Liu CC, Zhang XY, Xu XW, Zhang SR, Xie ZQ. The trade-off between safety and efficiency in hydraulic architecture in 31 woody species in a karst area. TREE PHYSIOLOGY 2011; 31:865-877. [PMID: 21865304 DOI: 10.1093/treephys/tpr076] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Karst topography is a special landscape shaped by the dissolution of one or more layers of soluble bedrock, usually carbonate rock such as limestone or dolomite. Due to subterranean drainage, overland flow, extraction of water by plants and evapotranspiration, there may be very limited surface water. The hydraulic architecture that plants use to adapt to karst topography is very interesting, but few systematic reports exist. The karst area in southwestern China is unique when compared with other karst areas at similar latitudes, because of its abundant precipitation, with rainfall concentrated in the growing season. In theory, resistance to water-stress-induced cavitation via air seeding should be accompanied by decreased pore hydraulic conductivity and stem hydraulic conductivity. However, evidence for such trade-offs across species is ambiguous. We measured the hydraulic structure and foliar stable carbon isotope ratios of 31 karst woody plants at three locations in Guizhou Province, China, to evaluate the functional coordination between resistance to cavitation and specific conductivity. We also applied phylogenetically independent contrast (PIC) analysis in situations where the inter-species correlations of functional traits may be biased on the potential similarity of closely related species. The average xylem tension measurement, at which 50% of hydraulic conductivity of the plants was lost (Ψ(50)), was only -1.27 MPa. Stem Ψ(50) was positively associated with specific conductance (K(s)) (P < 0.05) and leaf specific conductance (K(l)) (P < 0.05). However, the PIC correlation for both relationships was not statistically significant. δ(13)C was positively related to K(l) in both the traditional cross-species correlation analysis and the corresponding PIC correlations (P < 0.05). The Huber value (sapwood area:leaf area ratio) was negatively correlated with K(s) in both the traditional cross-species correlation and the corresponding PIC correlations (P < 0.01). The characteristics of hydraulic architecture measured in this study showed that karst plants in China are not highly cavitation-resistant species. This study also supports the idea that there may not be an evolutionary trade-off between resistance to cavitation and specific conductivity in woody plants. Whole-plant hydraulic adjustment may decouple the trade-off relationship between safety and efficiency at the branch level.
Collapse
Affiliation(s)
- Da-Yong Fan
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093, China
| | | | | | | | | | | | | |
Collapse
|
27
|
Isarangkool Na Ayutthaya S, Do FC, Pannangpetch K, Junjittakarn J, Maeght JL, Rocheteau A, Cochard H. Water loss regulation in mature Hevea brasiliensis: effects of intermittent drought in the rainy season and hydraulic regulation. TREE PHYSIOLOGY 2011; 31:751-62. [PMID: 21746745 DOI: 10.1093/treephys/tpr058] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Effects of soil and atmospheric drought on whole-tree transpiration (E(T)), leaf water potential (Ψ(L)) and whole-tree hydraulic conductance (K(T)) were investigated in mature rubber trees (Hevea brasiliensis, clone RRIM 600) during the full canopy stage in the rainy season in a drought-prone area of northeast Thailand. Under well-watered soil conditions, transpiration was tightly regulated in response to high evaporative demand, i.e., above reference evapotranspiration (ET(0)) ~2.2 mm day(-1) or maximum vapor pressure deficit ~1.8 kPa. When the trees experienced intermittent soil drought E(T) decreased sharply when relative extractable water in the top soil was < 0.4. The midday leaf water potential (Ψ(md)) on sunny days did not change as a function of soil drought and remained stable at approximately - 1.95 MPa, i.e., displaying isohydric behavior. The decrease in E(T) was mainly due to the change in K(T). K(T) remained constant over a wide range of environmental conditions and decreased sharply at low soil water availability. A simple hydraulic model incorporating critical minimum water potential and the response of whole-tree hydraulic conductance to relative extractable water correctly simulated patterns of transpiration over 6 months. We conclude that an explicit and simplified framework of hydraulic limitation hypothesis was sufficient to describe water use regulation of a mature rubber tree stand in water-limited conditions. Given the complexity of constraints in the soil-plant-atmosphere pathway, our results confirm the relevance of this approach to synthesize the overall behavior of trees under drought.
Collapse
|
28
|
Kraft NJB, Metz MR, Condit RS, Chave J. The relationship between wood density and mortality in a global tropical forest data set. THE NEW PHYTOLOGIST 2010; 188:1124-1136. [PMID: 21058950 DOI: 10.1111/j.1469-8137.2010.03444.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Wood density is thought to be an important indicator of plant life history because it is coupled to many aspects of whole-plant form and function. We used a hierarchical Bayesian approach to explain variation in mortality rates with wood density, drawing on data for 765,500 trees from 1639 species at 10 sites located across the Old and New World tropics. Mortality rates declined with increasing wood density at five of 10 sites. Similar negative trends were detected at four additional sites, while one site showed no relationship. Our model explained 40% of variation in mortality on average. Both wood density and mortality rates show a high degree of phylogenetic conservatism. Grouping species by family across sites in a second analysis, we found considerable variation in the relationship between wood density and mortality, with 10 of 27 families demonstrating a strong negative relationship. Our results highlight the importance of wood density as a functional trait in tropical forests, as it is strongly linked to variation in survival. However, the relationship varied among families, plots, and even census intervals within sites, indicating that the factors responsible for the relationship between wood density and mortality vary spatially, taxonomically and temporally.
Collapse
Affiliation(s)
- Nathan J B Kraft
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
| | | | | | | |
Collapse
|
29
|
Abstract
This review is focused on woody legumes from the southern continents. We highlight that the evolution of the Caesalpinioideae and Mimosoideae with old soils, with variable supplies of water and also with fire has produced a suite of advantageous physiological characteristics. These include good potential for nitrogen fixation and mechanisms for acquiring P. The latter includes the ability to form cluster roots and produce extracellular phosphatase enzymes. Further, many of the species in these subfamilies are known to synthesize in significant amounts osmotically compatible solutes, such as pinitol and other cyclitols/polyols, that help them cope with even severe drought conditions. In many cases, these species regenerate prolifically after fire from seed. Such species and their beneficial characters can now be better exploited to help sequester carbon, provide key nutrients such as nitrogen and phosphorus for companion crops and other plants and provide feedstocks for a range of industries, including energy industries.
Collapse
Affiliation(s)
- Mark A Adams
- Faculty of Agriculture, Food and Natural Resources, University of Sydney, Australian Technology Park, Eveleigh, NSW 2015, Australia.
| | | | | |
Collapse
|
30
|
Zeppel M, Tissue D, Taylor D, Macinnis-Ng C, Eamus D. Rates of nocturnal transpiration in two evergreen temperate woodland species with differing water-use strategies. TREE PHYSIOLOGY 2010; 30:988-1000. [PMID: 20566582 DOI: 10.1093/treephys/tpq053] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Nocturnal fluxes may be a significant factor in the annual water budget of forested ecosystems. Here, we assessed sap flow in two co-occurring evergreen species (Eucalyptus parramattensis and Angophora bakeri) in a temperate woodland for 2 years in order to quantify the magnitude of seasonal nocturnal sap flow (E(n)) under different environmental conditions. The two species showed different diurnal water relations, demonstrated by different diurnal curves of stomatal conductance, sap flow and leaf water potential. The relative influence of several microclimatic variables, including wind speed (U), vapour pressure deficit (D), the product of U and D (UD) and soil moisture content, were quantified. D exerted the strongest influence on E(n) (r² = 0.59-0.86), soil moisture content influenced E(n) when D was constant, but U and UD did not generally influence E(n). In both species, cuticular conductance (G(c)) was a small proportion of total leaf conductance (G(s)) and was not a major pathway for E(n). We found that E(n) was primarily a function of transpiration from the canopy rather than refilling of stem storage, with canopy transpiration accounting for 50-70% of nocturnal flows. Mean E(n) was 6-8% of the 24-h flux across seasons (spring, summer and winter), but was up to 19% of the 24-h flux on some days in both species. Despite different daytime strategies in water use of the two species, both species demonstrated low night-time water loss, suggesting similar controls on water loss at night. In order to account for the impact of E(n) on pre-dawn leaf water potential arising from the influence of disequilibria between root zone and leaf water potential, we also developed a simple model to more accurately predict soil water potential (ψ(s)).
Collapse
Affiliation(s)
- Melanie Zeppel
- Plant Functional Biology and Climate Change Cluster and Department of Environmental Sciences, University of Technology, Sydney, NSW 2007, Australia
| | | | | | | | | |
Collapse
|
31
|
Gotsch SG, Geiger EL, Franco AC, Goldstein G, Meinzer FC, Hoffmann WA. Allocation to leaf area and sapwood area affects water relations of co-occurring savanna and forest trees. Oecologia 2010; 163:291-301. [PMID: 20058025 DOI: 10.1007/s00442-009-1543-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Accepted: 12/08/2009] [Indexed: 11/28/2022]
Abstract
Water availability is a principal factor limiting the distribution of closed-canopy forest in the seasonal tropics, suggesting that forest tree species may not be well adapted to cope with seasonal drought. We studied 11 congeneric species pairs, each containing one forest and one savanna species, to test the hypothesis that forest trees have a lower capacity to maintain seasonal homeostasis in water relations relative to savanna species. To quantify this, we measured sap flow, leaf water potential (Psi(L)), stomatal conductance (g (s)), wood density, and Huber value (sapwood area:leaf area) of the 22 study species. We found significant differences in the water relations of these two species types. Leaf area specific hydraulic conductance of the soil/root/leaf pathway (G (t)) was greater for savanna species than forest species. The lower G (t) of forest trees resulted in significantly lower Psi(L) and g (s) in the late dry season relative to savanna trees. The differences in G (t) can be explained by differences in biomass allocation of savanna and forest trees. Savanna species had higher Huber values relative to forest species, conferring greater transport capacity on a leaf area basis. Forest trees have a lower capacity to maintain homeostasis in Psi(L) due to greater allocation to leaf area relative to savanna species. Despite significant differences in water relations, relationships between traits such as wood density and minimum Psi(L) were indistinguishable for the two species groups, indicating that forest and savanna share a common axis of water-use strategies involving multiple traits.
Collapse
Affiliation(s)
- Sybil G Gotsch
- Department of Plant Biology, North Carolina State University, Campus Box 7612, Raleigh, NC 27695-7612, USA.
| | | | | | | | | | | |
Collapse
|
32
|
Carter JL, White DA. Plasticity in the Huber value contributes to homeostasis in leaf water relations of a mallee Eucalypt with variation to groundwater depth. TREE PHYSIOLOGY 2009; 29:1407-1418. [PMID: 19797243 DOI: 10.1093/treephys/tpp076] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Information on how vegetation adapts to differences in water supply is critical for predicting vegetation survival, growth and water use, which, in turn, has important impacts on site hydrology. Many field studies assess adaptation to water stress by comparing between disparate sites, which makes it difficult to distinguish between physiological or morphological changes and long-term genetic adaptation. When planting trees into new environments, the phenotypic adaptations of a species to water stress will be of primary interest. This study examined the response to water availability of Eucalyptus kochii ssp. borealis (C. Gardner) D. Nicolle, commonly integrated with agriculture in south-western Australia for environmental and economic benefits. By choosing a site where the groundwater depth varied but where climate and soil type were the same, we were able to isolate tree response to water supply. Tree growth, leaf area and stand water use were much larger for trees over shallow groundwater than for trees over a deep water table below a silcrete hardpan. However, water use on a leaf area basis was similar in trees over deep and shallow groundwater, as were the minimum leaf water potential observed over different seasons and the turgor loss point. We conclude that homeostasis in leaf water use and water relations was maintained through a combination of stomatal control and adjustment of sapwood-to-leaf area ratios (Huber value). Differences in the Huber value with groundwater depth were associated with different sapwood-specific conductivity and water use on a sapwood area basis. Knowledge of the coordination between water supply, leaf area, sapwood area and leaf transpiration rate for different species will be important when predicting stand water use.
Collapse
Affiliation(s)
- Jennifer L Carter
- CSIRO Sustainable Ecosystems, Centre for Environment and Life Sciences, Private Bag 5, Wembley, Western Australia 6913, Australia.
| | | |
Collapse
|