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Lai Y, Tang S, Lambers H, Hietz P, Tang W, Gilliam FS, Lu X, Luo X, Lin Y, Wang S, Zeng F, Wang Q, Kuang Y. Global change progressively increases foliar nitrogen-phosphorus ratios in China's subtropical forests. GLOBAL CHANGE BIOLOGY 2024; 30:e17201. [PMID: 38385993 DOI: 10.1111/gcb.17201] [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: 09/06/2023] [Revised: 12/31/2023] [Accepted: 02/02/2024] [Indexed: 02/23/2024]
Abstract
Globally increased nitrogen (N) to phosphorus (P) ratios (N/P) affect the structure and functioning of terrestrial ecosystems, but few studies have addressed the variation of foliar N/P over time in subtropical forests. Foliar N/P indicates N versus P limitation in terrestrial ecosystems. Quantifying long-term dynamics of foliar N/P and their potential drivers is crucial for predicting nutrient status and functioning in forest ecosystems under global change. We detected temporal trends of foliar N/P, quantitatively estimated their potential drivers and their interaction between plant types (evergreen vs. deciduous and trees vs. shrubs), using 1811 herbarium specimens of 12 widely distributed species collected during 1920-2010 across China's subtropical forests. We found significant decreases in foliar P concentrations (23.1%) and increases in foliar N/P (21.2%). Foliar N/P increased more in evergreen species (22.9%) than in deciduous species (16.9%). Changes in atmospheric CO2 concentrations (P CO 2 $$ {\mathrm{P}}_{{\mathrm{CO}}_2} $$ ), atmospheric N deposition and mean annual temperature (MAT) dominantly contributed to the increased foliar N/P of evergreen species, whileP CO 2 $$ {\mathrm{P}}_{{\mathrm{CO}}_2} $$ , MAT, and vapor pressure deficit, to that of deciduous species. Under future Shared Socioeconomic Pathway (SSP) scenarios, increasing MAT andP CO 2 $$ {\mathrm{P}}_{{\mathrm{CO}}_2} $$ would continuously increase more foliar N/P in deciduous species than in evergreen species, with more 12.9%, 17.7%, and 19.4% versus 6.1%, 7.9%, and 8.9% of magnitudes under the scenarios of SSP1-2.6, SSP3-7.0, and SSP5-8.5, respectively. The results suggest that global change has intensified and will progressively aggravate N-P imbalance, further altering community composition and ecosystem functioning of subtropical forests.
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Affiliation(s)
- Yuan Lai
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Songbo Tang
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Hans Lambers
- School of Biological Sciences, University of Western Australia, Perth, Western Australia, Australia
| | - Peter Hietz
- Institute of Botany, University of Natural Resources and Life Sciences, Vienna, Austria
| | | | - Frank S Gilliam
- Department of Earth and Environmental Sciences, University of West Florida, Pensacola, Florida, USA
| | - Xiankai Lu
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Xianzhen Luo
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Yutong Lin
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Shu Wang
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Feiyan Zeng
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Qi Wang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-Environmental Pollution Control and Management, Institute of Eco-Environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou, China
| | - Yuanwen Kuang
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
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Holloway-Phillips M, Cernusak LA, Nelson DB, Lehmann MM, Tcherkez G, Kahmen A. Covariation between oxygen and hydrogen stable isotopes declines along the path from xylem water to wood cellulose across an aridity gradient. THE NEW PHYTOLOGIST 2023; 240:1758-1773. [PMID: 37680025 DOI: 10.1111/nph.19248] [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: 01/17/2023] [Accepted: 08/16/2023] [Indexed: 09/09/2023]
Abstract
Oxygen and hydrogen isotopes of cellulose in plant biology are commonly used to infer environmental conditions, often from time series measurements of tree rings. However, the covariation (or the lack thereof) between δ18 O and δ2 H in plant cellulose is still poorly understood. We compared plant water, and leaf and branch cellulose from dominant tree species across an aridity gradient in Northern Australia, to examine how δ18 O and δ2 H relate to each other and to mean annual precipitation (MAP). We identified a decline in covariation from xylem to leaf water, and onwards from leaf to branch wood cellulose. Covariation in leaf water isotopic enrichment (Δ) was partially preserved in leaf cellulose but not branch wood cellulose. Furthermore, whilst δ2 H was well-correlated between leaf and branch, there was an offset in δ18 O between organs that increased with decreasing MAP. Our findings strongly suggest that postphotosynthetic isotope exchange with water is more apparent for oxygen isotopes, whereas variable kinetic and nonequilibrium isotope effects add complexity to interpreting metabolic-induced δ2 H patterns. Varying oxygen isotope exchange in wood and leaf cellulose must be accounted for when δ18 O is used to reconstruct climatic scenarios. Conversely, comparing δ2 H and δ18 O patterns may reveal environmentally induced shifts in metabolism.
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Affiliation(s)
- Meisha Holloway-Phillips
- Department of Environmental Sciences-Botany, University of Basel, 4056, Basel, Switzerland
- Research Unit of Forest Dynamics, Research Group of Ecosystem Ecology, Stable Isotope Research Centre, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903, Birmendsorf, Switzerland
| | - Lucas A Cernusak
- College of Science and Engineering, James Cook University, Cairns, Qld, 4878, Australia
| | - Daniel B Nelson
- Department of Environmental Sciences-Botany, University of Basel, 4056, Basel, Switzerland
| | - Marco M Lehmann
- Research Unit of Forest Dynamics, Research Group of Ecosystem Ecology, Stable Isotope Research Centre, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903, Birmendsorf, Switzerland
| | - Guillaume Tcherkez
- Research School of Biology, College of Science, Australian National University, Canberra, ACT, 2601, Australia
- Institut de Recherche en Horticulture et Semences, Université d'Angers, INRAe, 42 rue Georges Morel, 49070, Beaucouzé, France
| | - Ansgar Kahmen
- Department of Environmental Sciences-Botany, University of Basel, 4056, Basel, Switzerland
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Ampornpitak R, Nathalang A, Tor-ngern P. Water-use characteristics of Syzygium antisepticum and Adinandra integerrima in a secondary forest of Khao Yai National Park in Thailand with implications for environmental management. PeerJ 2023; 11:e16525. [PMID: 38050611 PMCID: PMC10693818 DOI: 10.7717/peerj.16525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 11/05/2023] [Indexed: 12/06/2023] Open
Abstract
Background Southeast Asia has experienced widespread deforestation and change in land use. Consequently, many reforestation projects have been initiated in this region. However, it is imperative to carefully choose the tree species for planting, especially in light of the increasing climate variability and the potential alteration of plantation on the watershed water balance. Thus, the information regarding water-use characteristics of various tree species and sizes is critical in the tree species selection for reforestation. Methods We estimated tree water use (T) of dominant species including Syzygium antisepticum and Adinandra integerrima, hereafter Sa and Ai, respectively, in a secondary tropical forest in Khao Yai National Park, Thailand, using sap flow data, and compared T between species and size classes. Additionally, we evaluated the responses of T of both species in each size class to environmental factors including soil moisture and vapor pressure deficit (VPD). Results Results showed consistently higher T in Sa compared to Ai across ranges of VPD and soil moisture. Under low soil moisture, T of Sa responded to VPD, following a saturating exponential pattern while Ai maintained T across different VPD levels, irrespective of tree size. No responses of T to VPD were observed in either species when soil water was moderate. When soil moisture was high, T of both species significantly increased and saturated at high VPD, albeit the responses were less sensitive in large trees. Our results imply that Ai may be suitable for reforestation in water-limited areas where droughts frequently occur to minimize reforestation impact on water availability to downstream ecosystems. In contrast, Sa should be planted in regions with abundant and reliable water resources. However, a mixed species plantation should be generally considered to increase forest resilience to increasing climate variation.
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Affiliation(s)
- Ratchanon Ampornpitak
- International Program in Hazardous Substance and Environmental Management, Graduate School, Chulalongkorn University, Bangkok, Thailand
- Center of Excellence on Hazardous Substance Management, Chulalongkorn University, Bangkok, Thailand
| | - Anuttara Nathalang
- National Biobank of Thailand, National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Pantana Tor-ngern
- Department of Environmental Science, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
- Water Science and Technology for Sustainable Environment Research Unit, Chulalongkorn University, Bangkok, Thailand
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Florin SA, Roberts P, Marwick B, Patton NR, Shulmeister J, Lovelock CE, Barry LA, Hua Q, Nango M, Djandjomerr D, Fullagar R, Wallis LA, Fairbairn AS, Clarkson C. Pandanus nutshell generates a palaeoprecipitation record for human occupation at Madjedbebe, northern Australia. Nat Ecol Evol 2021; 5:295-303. [PMID: 33495592 PMCID: PMC7929916 DOI: 10.1038/s41559-020-01379-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 12/03/2020] [Indexed: 11/11/2022]
Abstract
Little is known about the Pleistocene climatic context of northern Australia at the time of early human settlement. Here we generate a palaeoprecipitation proxy using stable carbon isotope analysis of modern and archaeological pandanus nutshell from Madjedbebe, Australia's oldest known archaeological site. We document fluctuations in precipitation over the last 65,000 years and identify periods of lower precipitation during the penultimate and last glacial stages, Marine Isotope Stages 4 and 2. However, the lowest effective annual precipitation is recorded at the present time. Periods of lower precipitation, including the earliest phase of occupation, correspond with peaks in exotic stone raw materials and artefact discard at the site. This pattern is interpreted as suggesting increased group mobility and intensified use of the region during drier periods.
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Affiliation(s)
- S Anna Florin
- School of Social Science, The University of Queensland, Brisbane, Queensland, Australia.
- Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, University of Wollongong, Wollongong, New South Wales, Australia.
| | - Patrick Roberts
- School of Social Science, The University of Queensland, Brisbane, Queensland, Australia
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany
| | - Ben Marwick
- Department of Anthropology, University of Washington, Seattle, WA, USA
| | - Nicholas R Patton
- School of Earth and Environment, University of Canterbury, Christchurch, New Zealand
| | - James Shulmeister
- Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, University of Wollongong, Wollongong, New South Wales, Australia
- School of Earth and Environment, University of Canterbury, Christchurch, New Zealand
- School of Earth and Environmental Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Catherine E Lovelock
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Linda A Barry
- Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia
| | - Quan Hua
- Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia
| | - May Nango
- Gundjeihmi Aboriginal Corporation, Jabiru, Northern Territory, Australia
| | | | - Richard Fullagar
- Centre for Archaeological Science, School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, New South Wales, Australia
| | - Lynley A Wallis
- Griffith Centre for Social and Cultural Research, Griffith University, Nathan, Queensland, Australia
| | - Andrew S Fairbairn
- School of Social Science, The University of Queensland, Brisbane, Queensland, Australia.
- Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, University of Wollongong, Wollongong, New South Wales, Australia.
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany.
| | - Chris Clarkson
- School of Social Science, The University of Queensland, Brisbane, Queensland, Australia.
- Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, University of Wollongong, Wollongong, New South Wales, Australia.
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany.
- Centre for Archaeological Science, School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, New South Wales, Australia.
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Water use of Prosopis juliflora and its impacts on catchment water budget and rural livelihoods in Afar Region, Ethiopia. Sci Rep 2021; 11:2688. [PMID: 33514795 PMCID: PMC7846740 DOI: 10.1038/s41598-021-81776-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 01/05/2021] [Indexed: 01/30/2023] Open
Abstract
Dense impenetrable thickets of invasive trees and shrubs compete with other water users and thus disrupt ecosystem functioning and services. This study assessed water use by the evergreen Prosopis juliflora, one of the dominant invasive tree species in semi-arid and arid ecosystems in the tropical regions of Eastern Africa. The objectives of the study were to (1) analyze the seasonal water use patterns of P. juliflora in various locations in Afar Region, Ethiopia, (2) up-scale the water use from individual tree transpiration and stand evapotranspiration (ET) to the entire invaded area, and 3) estimate the monetary value of water lost due to the invasion. The sap flow rates of individual P. juliflora trees were measured using the heat ratio method while stand ET was quantified using the eddy covariance method. Transpiration by individual trees ranged from 1-36 L/day, with an average of 7 L of water per tree per day. The daily average transpiration of a Prosopis tree was about 3.4 (± 0.5) mm and the daily average ET of a dense Prosopis stand was about 3.7 (± 1.6) mm. Using a fractional cover map of P. juliflora (over an area of 1.18 million ha), water use of P. juliflora in Afar Region was estimated to be approximately 3.1-3.3 billion m3/yr. This volume of water would be sufficient to irrigate about 460,000 ha of cotton or 330,000 ha of sugar cane, the main crops in the area, which would generate an estimated net benefit of approximately US$ 320 million and US$ 470 million per growing season from cotton and sugarcane, respectively. Hence, P. juliflora invasion in the Afar Region has serious impacts on water availability and on the provision of other ecosystem services and ultimately on rural livelihoods.
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Santini F, Climent JM, Voltas J. Phenotypic integration and life history strategies among populations of Pinus halepensis: an insight through structural equation modelling. ANNALS OF BOTANY 2020; 124:1161-1172. [PMID: 31115443 PMCID: PMC6943711 DOI: 10.1093/aob/mcz088] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 05/20/2019] [Indexed: 05/26/2023]
Abstract
BACKGROUND AND AIMS Understanding inter-population variation in the allocation of resources to specific anatomical compartments and physiological processes is crucial to disentangle adaptive patterns in forest species. This work aims to evaluate phenotypic integration and trade-offs among functional traits as determinants of life history strategies in populations of a circum-Mediterranean pine that dwells in environments where water and other resources are in limited supply. METHODS Adult individuals of 51 populations of Pinus halepensis grown in a common garden were characterized for 11 phenotypic traits, including direct and indirect measures of water uptake at different depths, leaf area, stomatal conductance, chlorophyll content, non-structural carbohydrates, stem diameter and tree height, age at first reproduction and cone production. The population differentiation in these traits was tested through analysis of variance (ANOVA). The resulting populations' means were carried forward to a structural equation model evaluating phenotypic integration between six latent variables (summer water uptake depth, summer transpiration, spring photosynthetic capacity, growth, reserve accumulation and reproduction). KEY RESULTS Water uptake depth and transpiration covaried negatively among populations, as the likely result of a common selective pressure for drought resistance, while spring photosynthetic capacity was lower in populations originating from dry areas. Transpiration positively influenced growth, while growth was negatively related to reproduction and reserves among populations. Water uptake depth negatively influenced reproduction. CONCLUSIONS The observed patterns indicate a differentiation in life cycle features between fast-growing and slow-growing populations, with the latter investing significantly more in reproduction and reserves. We speculate that such contrasting strategies result from different arrays of life history traits underlying the very different ecological conditions that the Aleppo pine must face across its distribution range. These comprise, principally, drought as the main stressor and fire as the main ecological disturbance of the Mediterranean basin.
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Affiliation(s)
- Filippo Santini
- Joint Research Unit CTFC – AGROTECNIO, Lleida, Spain
- Department of Crop and Forest Sciences, University of Lleida, Lleida, Spain
| | - José M Climent
- INIA-CIFOR, Department of Ecology and Forest Genetics, Madrid, Spain
| | - Jordi Voltas
- Joint Research Unit CTFC – AGROTECNIO, Lleida, Spain
- Department of Crop and Forest Sciences, University of Lleida, Lleida, Spain
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Bloomfield KJ, Prentice IC, Cernusak LA, Eamus D, Medlyn BE, Rumman R, Wright IJ, Boer MM, Cale P, Cleverly J, Egerton JJG, Ellsworth DS, Evans BJ, Hayes LS, Hutchinson MF, Liddell MJ, Macfarlane C, Meyer WS, Togashi HF, Wardlaw T, Zhu L, Atkin OK. The validity of optimal leaf traits modelled on environmental conditions. THE NEW PHYTOLOGIST 2019; 221:1409-1423. [PMID: 30242841 DOI: 10.1111/nph.15495] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 09/07/2018] [Indexed: 06/08/2023]
Abstract
The ratio of leaf intercellular to ambient CO2 (χ) is modulated by stomatal conductance (gs ). These quantities link carbon (C) assimilation with transpiration, and along with photosynthetic capacities (Vcmax and Jmax ) are required to model terrestrial C uptake. We use optimization criteria based on the growth environment to generate predicted values of photosynthetic and water-use efficiency traits and test these against a unique dataset. Leaf gas-exchange parameters and carbon isotope discrimination were analysed in relation to local climate across a continental network of study sites. Sun-exposed leaves of 50 species at seven sites were measured in contrasting seasons. Values of χ predicted from growth temperature and vapour pressure deficit were closely correlated to ratios derived from C isotope (δ13 C) measurements. Correlations were stronger in the growing season. Predicted values of photosynthetic traits, including carboxylation capacity (Vcmax ), derived from δ13 C, growth temperature and solar radiation, showed meaningful agreement with inferred values derived from gas-exchange measurements. Between-site differences in water-use efficiency were, however, only weakly linked to the plant's growth environment and did not show seasonal variation. These results support the general hypothesis that many key parameters required by Earth system models are adaptive and predictable from plants' growth environments.
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Affiliation(s)
- Keith J Bloomfield
- Division of Plant Sciences, Research School of Biology, The Australian National University, Building 46, Canberra, ACT, 2601, Australia
| | - I Colin Prentice
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
- AXA Chair of Biosphere and Climate Impacts, Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, SL5 7PY, UK
| | - Lucas A Cernusak
- Department of Marine and Tropical Biology, James Cook University, Cairns, Qld, 4878, Australia
| | - Derek Eamus
- School of Life Sciences, University of Technology Sydney, NSW, 2007, Australia
| | - Belinda E Medlyn
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Rizwana Rumman
- School of Life Sciences, University of Technology Sydney, NSW, 2007, Australia
| | - Ian J Wright
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
| | - Matthias M Boer
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Peter Cale
- Australian Landscape Trust, Renmark, SA, 5341, Australia
| | - James Cleverly
- School of Life Sciences, University of Technology Sydney, NSW, 2007, Australia
- Terrestrial Ecosystem Research Network (TERN), University of Technology Sydney, Goddard Building, The University of Queensland, St Lucia, QLD 4072, Australia
| | - John J G Egerton
- Division of Plant Sciences, Research School of Biology, The Australian National University, Building 46, Canberra, ACT, 2601, Australia
| | - David S Ellsworth
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Bradley J Evans
- Faculty of Agriculture and Environment, Department of Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
| | - Lucy S Hayes
- Division of Plant Sciences, Research School of Biology, The Australian National University, Building 46, Canberra, ACT, 2601, Australia
| | - Michael F Hutchinson
- Fenner School of Environment and Society, Australian National University, Canberra, ACT, 2601, Australia
| | - Michael J Liddell
- Centre for Tropical, Environmental, and Sustainability Sciences, James Cook University, Cairns, Qld, 4878, Australia
| | - Craig Macfarlane
- CSIRO Land and Water, Private Bag 5, Wembley, WA, 6913, Australia
| | - Wayne S Meyer
- Earth and Environmental Sciences, University of Adelaide, Adelaide, SA, 5064, Australia
| | - Henrique F Togashi
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
| | - Tim Wardlaw
- ARC Centre for Forest Value, University of Tasmania, Hobart, TAS, 7005, Australia
| | - Lingling Zhu
- Division of Plant Sciences, Research School of Biology, The Australian National University, Building 46, Canberra, ACT, 2601, Australia
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Building 134, Canberra, ACT, 2601, Australia
| | - Owen K Atkin
- Division of Plant Sciences, Research School of Biology, The Australian National University, Building 46, Canberra, ACT, 2601, Australia
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Building 134, Canberra, ACT, 2601, Australia
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Garrido M, Silva H, Franck N, Arenas J, Acevedo E. Evaluation of Morpho-Physiological Traits Adjustment of Prosopis tamarugo Under Long-Term Groundwater Depletion in the Hyper-Arid Atacama Desert. FRONTIERS IN PLANT SCIENCE 2018; 9:453. [PMID: 29686691 PMCID: PMC5900453 DOI: 10.3389/fpls.2018.00453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 03/22/2018] [Indexed: 05/06/2023]
Abstract
Water extraction from the underground aquifers of the Pampa del Tamarugal (Atacama Desert, Chile) reduced the growing area of Prosopis tamarugo, a strict phreatic species endemic to northern Chile. The objective of this work was to evaluate the effect of various architectural and morpho-physiological traits adjustment of P. tamarugo subjected to three groundwater depletion intervals (GWDr): <1 m (control), 1-4 m and 6-9 m. The traits were evaluated at three levels, plant [height, trunk cross-section area, leaf fraction (fGCC), and crown size], organ [length of internodes, leaf mass per unit area (LMA), leaflet mass and area], and tissue level [wood density (WD), leaf 13C, 18O isotope composition (δ), and intrinsic water use efficiency (iWUE)]. In addition, soil water content (VWC) to 1.3 m soil depth, pre-dawn and midday water potential difference (ΔΨ), and stomatal conductance (gs) were evaluated. At the deeper GWDr, P. tamarugo experienced significant growth restriction and reduced fGCC, the remaining canopy had a significantly higher LMA associated with smaller leaflets. No differences in internode length and WD were observed. Values for δ13C and δ18O indicated that as GWDr increased, iWUE increased as a result of partial stomata closure with no significant effect on net assimilation over time. The morpho-physiological changes experienced by P. tamarugo allowed it to acclimate and survive in a condition of groundwater depletion, keeping a functional but diminished canopy. These adjustments allowed maintenance of a relatively high gs; ΔΨ was not different among GWDrs despite smaller VWC at greater GWDr. Although current conservation initiatives of this species are promising, forest deterioration is expected continue as groundwater depth increases.
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Affiliation(s)
- Marco Garrido
- Soil-Plant-Water Relations Laboratory, Agricultural Production Department, Faculty of Agronomical Sciences, Universidad de Chile, Santiago, Chile
| | - Herman Silva
- Soil-Plant-Water Relations Laboratory, Agricultural Production Department, Faculty of Agronomical Sciences, Universidad de Chile, Santiago, Chile
| | - Nicolás Franck
- Soil-Plant-Water Relations Laboratory, Agricultural Production Department, Faculty of Agronomical Sciences, Universidad de Chile, Santiago, Chile
| | - Jorge Arenas
- Faculty of Natural Renewable Resources, Desert Agriculture, Universidad Arturo Prat, Iquique, Chile
| | - Edmundo Acevedo
- Soil-Plant-Water Relations Laboratory, Agricultural Production Department, Faculty of Agronomical Sciences, Universidad de Chile, Santiago, Chile
- *Correspondence: Edmundo Acevedo
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Zolfaghar S, Villalobos-Vega R, Zeppel M, Cleverly J, Rumman R, Hingee M, Boulain N, Li Z, Eamus D. Transpiration of Eucalyptus woodlands across a natural gradient of depth-to-groundwater. TREE PHYSIOLOGY 2017; 37:961-975. [PMID: 28369559 DOI: 10.1093/treephys/tpx024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 02/24/2017] [Indexed: 05/22/2023]
Abstract
Water resources and their management present social, economic and environmental challenges, with demand for human consumptive, industrial and environmental uses increasing globally. However, environmental water requirements, that is, the allocation of water to the maintenance of ecosystem health, are often neglected or poorly quantified. Further, transpiration by trees is commonly a major determinant of the hydrological balance of woodlands but recognition of the role of groundwater in hydrological balances of woodlands remains inadequate, particularly in mesic climates. In this study, we measured rates of tree water-use and sapwood 13C isotopic ratio in a mesic, temperate Eucalypt woodland along a naturally occurring gradient of depth-to-groundwater (DGW), to examine daily, seasonal and annual patterns of transpiration. We found that: (i) the maximum rate of stand transpiration was observed at the second shallowest site (4.3 m) rather than the shallowest (2.4 m); (ii) as DGW increased from 4.3 to 37.5 m, stand transpiration declined; (iii) the smallest rate of stand transpiration was observed at the deepest (37.5 m) site; (iv) intrinsic water-use efficiency was smallest at the two intermediate DGW sites as reflected in the Δ13C of the most recently formed sapwood and largest at the deepest and shallowest DGW sites, reflecting the imposition of flooding at the shallowest site and the inaccessibility of groundwater at the deepest site; and (v) there was no evidence of convergence in rates of water-use for co-occurring species at any site. We conclude that even in mesic environments groundwater can be utilized by trees. We further conclude that these forests are facultatively groundwater-dependent when groundwater depth is <9 m and suggest that during drier-than-average years the contribution of groundwater to stand transpiration is likely to increase significantly at the three shallowest DGW sites.
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Affiliation(s)
- Sepideh Zolfaghar
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
- National Centre for Groundwater Research and Training, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
| | - Randol Villalobos-Vega
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
- National Centre for Groundwater Research and Training, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
| | - Melanie Zeppel
- Department of Biological Sciences, Macquarie University, Balaclava Road, North Ryde, NSW 2107, Australia
| | - James Cleverly
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW2007, Australia
| | - Rizwana Rumman
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
- National Centre for Groundwater Research and Training, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
| | - Matthew Hingee
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW2007, Australia
| | - Nicolas Boulain
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW2007, Australia
| | - Zheng Li
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW2007, Australia
| | - Derek Eamus
- School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
- National Centre for Groundwater Research and Training, University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
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Hernandez MJ, Montes F, Ruiz F, Lopez G, Pita P. The effect of vapour pressure deficit on stomatal conductance, sap pH and leaf-specific hydraulic conductance in Eucalyptus globulus clones grown under two watering regimes. ANNALS OF BOTANY 2016; 117:1063-71. [PMID: 27052343 PMCID: PMC4866316 DOI: 10.1093/aob/mcw031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 11/19/2015] [Accepted: 01/08/2016] [Indexed: 05/30/2023]
Abstract
BACKGROUND AND AIMS Stomatal conductance has long been considered of key interest in the study of plant adaptation to water stress. The expected increase in extreme meteorological events under a climate change scenario may compromise survival in Eucalyptus globulus plantations established in south-western Spain. We investigated to what extent changes in stomatal conductance in response to high vapour pressure deficits and water shortage are mediated by hydraulic and chemical signals in greenhouse-grown E. globulus clones. METHODS Rooted cuttings were grown in pots and submitted to two watering regimes. Stomatal conductance, shoot water potential, sap pH and hydraulic conductance were measured consecutively in each plant over 4 weeks under vapour pressure deficits ranging 0·42 to 2·25 kPa. Evapotranspiration, growth in leaf area and shoot biomass were also determined. KEY RESULTS There was a significant effect of both clone and watering regime in stomatal conductance and leaf-specific hydraulic conductance, but not in sap pH. Sap pH decreased as water potential and stomatal conductance decreased under increasing vapour pressure deficit. There was no significant relationship between stomatal conductance and leaf-specific hydraulic conductance. Stomata closure precluded shoot water potential from falling below -1·8 MPa. The percentage loss of hydraulic conductance ranged from 40 to 85 %. The highest and lowest leaf-specific hydraulic conductances were measured in clones from the same half-sib families. Water shortage reduced growth and evapotranspiration, decreases in evapotranspiration ranging from 14 to 32 % in the five clones tested. CONCLUSIONS Changes in sap pH seemed to be a response to changes in atmospheric conditions rather than soil water in the species. Stomata closed after a considerable amount of hydraulic conductance was lost, although intraspecific differences in leaf-specific hydraulic conductance suggest the possibility of selection for improved productivity under water-limiting conditions combined with high temperatures in the early stages of growth.
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Affiliation(s)
| | | | - Federico Ruiz
- ENCE S.A., Ctra A-5000 km 7·5. Apartado 223, 21007 Huelva, Spain
| | - Gustavo Lopez
- ENCE S.A., Ctra A-5000 km 7·5. Apartado 223, 21007 Huelva, Spain
| | - Pilar Pita
- School of Forestry Engineering and Natural Resources, Technical University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
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11
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Below-ground interspecific competition for water in a rubber agroforestry system may enhance water utilization in plants. Sci Rep 2016; 6:19502. [PMID: 26781071 PMCID: PMC4726060 DOI: 10.1038/srep19502] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Accepted: 12/14/2015] [Indexed: 11/22/2022] Open
Abstract
Rubber-based (Hevea brasiliensis) agroforestry systems are regarded as the best way to improve the sustainability of rubber monocultures, but few reports have examined water use in such systems. Accordingly, we tested whether interplanting facilitates water utilization of rubber trees using stable isotope (δD, δ18O, and δ13C) methods and by measuring soil water content (SWC), shoot potential, and leaf C and N concentrations in a Hevea-Flemingia agroforestry system in Xishuangbanna, southwestern China. We detected a big difference in the utilization of different soil layer water between both species in this agroforestry system, as evidenced by the opposite seasonal fluctuations in both δD and δ18O in stem water. However, similar predawn shoot potential of rubber trees at both sites demonstrating that the interplanted species did not affect the water requirements of rubber trees greatly. Rubber trees with higher δ13C and more stable physiological indexes in this agroforestry system showed higher water use efficiency (WUE) and tolerance ability, and the SWC results suggested this agroforestry is conductive to water conservation. Our results clearly indicated that intercropping legume plants with rubber trees can benefit rubber trees own higher N supply, increase their WUE and better utilize soil water of each soil layer.
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12
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Klein T, Randin C, Körner C. Water availability predicts forest canopy height at the global scale. Ecol Lett 2015; 18:1311-20. [PMID: 26423470 DOI: 10.1111/ele.12525] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 07/26/2015] [Accepted: 08/24/2015] [Indexed: 11/28/2022]
Abstract
The tendency of trees to grow taller with increasing water availability is common knowledge. Yet a robust, universal relationship between the spatial distribution of water availability and forest canopy height (H) is lacking. Here, we created a global water availability map by calculating an annual budget as the difference between precipitation (P) and potential evapotranspiration (PET) at a 1-km spatial resolution, and in turn correlated it with a global H map of the same resolution. Across forested areas over the globe, Hmean increased with P-PET, roughly: Hmean (m) = 19.3 + 0.077*(P-PET). Maximum forest canopy height also increased gradually from ~ 5 to ~ 50 m, saturating at ~ 45 m for P-PET > 500 mm. Forests were far from their maximum height potential in cold, boreal regions and in disturbed areas. The strong association between forest height and P-PET provides a useful tool when studying future forest dynamics under climate change, and in quantifying anthropogenic forest disturbance.
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Affiliation(s)
- Tamir Klein
- Institute of Botany, University of Basel, Schönbeinstrasse 6, Basel, 4056, Switzerland
| | - Christophe Randin
- Institute of Botany, University of Basel, Schönbeinstrasse 6, Basel, 4056, Switzerland.,Department of Ecology & Evolution, University of Lausanne, Basel, Switzerland
| | - Christian Körner
- Institute of Botany, University of Basel, Schönbeinstrasse 6, Basel, 4056, Switzerland
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13
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Zolfaghar S, Villalobos-Vega R, Zeppel M, Eamus D. The hydraulic architecture of Eucalyptus trees growing across a gradient of depth-to-groundwater. FUNCTIONAL PLANT BIOLOGY : FPB 2015; 42:888-898. [PMID: 32480731 DOI: 10.1071/fp14324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 06/09/2015] [Indexed: 06/11/2023]
Abstract
Heterogeneity in water availability acts as an important driver of variation in plant structure and function. Changes in hydraulic architecture represent a key mechanism by which adaptation to changes in water availability can be expressed in plants. The aim of this study was to investigate whether differences in depth-to-groundwater influence the hydraulic architecture of Eucalyptus trees in remnant woodlands within mesic environments. Hydraulic architecture of trees was examined in winter and summer by measuring the following traits: Huber value (HV: the ratio between sapwood area and leaf area), branch hydraulic conductivity (leaf and sapwood area specific), sapwood density, xylem vulnerability (P50 and Pe) and hydraulic safety margins across four sites where depth-to-groundwater ranged from 2.4 to 37.5m. Huber value increased significantly as depth-to-groundwater increased. Neither sapwood density nor branch hydraulic conductivity (sapwood and leaf area specific) varied significantly across sites. Xylem vulnerability to embolism (represented by P50 and Pe) in both seasons was significantly and negatively correlated with depth-to-groundwater. Hydraulic safety margins increased with increasing depth-to-groundwater and therefore trees growing at sites with deeper water tables were less sensitive to drought induced embolism. These results showed plasticity in some, but not all, hydraulic traits (as reflected in HV, P50, Pe and hydraulic safety margin) in response to increase in depth-to-groundwater in a mesic environment.
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Affiliation(s)
- Sepideh Zolfaghar
- University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
| | | | - Melanie Zeppel
- Department of Biological Sciences, Macquarie University, Balaclava Road, North Ryde, NSW 2109, Australia
| | - Derek Eamus
- University of Technology Sydney, PO Box 123, Broadway, Sydney, NSW 2007, Australia
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14
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Zolfaghar S, Villalobos-Vega R, Cleverly J, Eamus D. Co-ordination among leaf water relations and xylem vulnerability to embolism of Eucalyptus trees growing along a depth-to-groundwater gradient. TREE PHYSIOLOGY 2015; 35:732-743. [PMID: 26023059 DOI: 10.1093/treephys/tpv039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 04/19/2015] [Indexed: 06/04/2023]
Abstract
The importance of groundwater resources in arid and semi-arid areas for plant survival is well documented. However, there have been few studies examining the importance and impacts of groundwater availability in mesic environments. The aim of this study was to determine how depth-to-groundwater (DGW) impacts on leaf water relations, leaf structure and branch xylem vulnerability to embolism in a mesic environment. We hypothesize that increasing DGW results in increased resistance to drought stress and that this will be manifested across leaf and branch attributes pertaining to water relations. We further investigate whether there is co-ordination across leaf and branch-scale level responses to increased DGW. Four species were used in this study: Eucalyptus globoidea Blakely, E. piperita Sm., E. sclerophylla (Blakely) L.A.S.Johnson & Blaxell and E. sieberi L.A.S.Johnson. Six sites were chosen along an 11 km transect to span a range of average DGW: 2.4, 4.3, 9.8, 13, 16.3 and 37.5 m. Leaf water relations of trees showed less sensitivity to drought stress as DGW increased. This was reflected in significantly lower leaf turgor loss point and maximum osmotic potential, increased maximum turgor and a reduced leaf relative water content as DGW increased. At shallow DGW sites, minimum diurnal leaf water potentials were generally more negative than leaf water potential at zero turgor, but the reverse was observed at deep sites, indicating a larger growth potential safety margin at deep sites compared with shallow sites. Leaf cell wall elasticity varied independently of DGW. Xylem vulnerability to embolism was quantified as the water potential associated with 50% loss of conductance (P 50). In both summer and winter P 50 was significantly and negatively correlated with DGW. Co-ordination between leaf- and branch-level responses to increase in DGW was apparent, which strongly supports the conclusion that groundwater supply influenced woodland structure and functional behaviour.
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Affiliation(s)
- Sepideh Zolfaghar
- University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia National Centre for Groundwater Research and Training, University of Technology Sydney, PO BOX 123, Broadway, NSW, 2007, Australia
| | - Randol Villalobos-Vega
- University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia National Centre for Groundwater Research and Training, University of Technology Sydney, PO BOX 123, Broadway, NSW, 2007, Australia
| | - James Cleverly
- University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia National Centre for Groundwater Research and Training, University of Technology Sydney, PO BOX 123, Broadway, NSW, 2007, Australia
| | - Derek Eamus
- University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia National Centre for Groundwater Research and Training, University of Technology Sydney, PO BOX 123, Broadway, NSW, 2007, Australia
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15
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Arndt SK, Sanders GJ, Bristow M, Hutley LB, Beringer J, Livesley SJ. Vulnerability of native savanna trees and exotic Khaya senegalensis to seasonal drought. TREE PHYSIOLOGY 2015; 35:783-791. [PMID: 25934988 DOI: 10.1093/treephys/tpv037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 04/06/2015] [Indexed: 06/04/2023]
Abstract
Seasonally dry ecosystems present a challenge to plants to maintain water relations. While native vegetation in seasonally dry ecosystems have evolved specific adaptations to the long dry season, there are risks to introduced exotic species. African mahogany, Khaya senegalensis Desr. (A. Juss.), is an exotic plantation species that has been introduced widely in Asia and northern Australia, but it is unknown if it has the physiological or phenotypic plasticity to cope with the strongly seasonal patterns of water availability in the tropical savanna climate of northern Australia. We investigated the gas exchange and water relations traits and adjustments to seasonal drought in K. senegalensis and native eucalypts (Eucalyptus tetrodonta F. Muell. and Corymbia latifolia F. Muell.) in a savanna ecosystem in northern Australia. The native eucalypts did not exhibit any signs of drought stress after 3 months of no rainfall and probably had access to deeper soil moisture late into the dry season. Leaf water potential, stomatal conductance, transpiration and photosynthesis all remained high in the dry season but osmotic adjustment was not observed. Overstorey leaf area index (LAI) was 0.6 in the native eucalypt savanna and did not change between wet and dry seasons. In contrast, the K. senegalensis plantation in the wet season was characterized by a high water potential, high stomatal conductance and transpiration and a high LAI of 2.4. In the dry season, K. senegalensis experienced mild drought stress with a predawn water potential -0.6 MPa. Overstorey LAI was halved, and stomatal conductance and transpiration drastically reduced, while minimum leaf water potentials did not change (-2 MPa) and no osmotic adjustment occurred. Khaya senegalensis exhibited an isohydric behaviour and also had a lower hydraulic vulnerability to cavitation in leaves, with a P50 of -2.3 MPa. The native eucalypts had twice the maximum leaf hydraulic conductance but a much higher P50 of -1.5 MPa. Khaya senegalensis has evolved in a wet-dry tropical climate in West Africa (600-800 mm) and appears to be well suited to the seasonal savanna climate of northern Australia. The species exhibited a large phenotypic plasticity through leaf area adjustments and conservative isohydric behaviour in the 6 months dry season while operating well above its critical hydraulic threshold.
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Affiliation(s)
- Stefan K Arndt
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, VIC 3121, Australia Terrestrial Ecosystem Research, Department of Microbiology and Ecosystem Science, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Gregor J Sanders
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, VIC 3121, Australia
| | - Mila Bristow
- School of Environment, Charles Darwin University, Casuarina, NT 0810, Australia
| | - Lindsay B Hutley
- School of Environment, Charles Darwin University, Casuarina, NT 0810, Australia
| | - Jason Beringer
- School of Earth and Environment, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Stephen J Livesley
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, VIC 3121, Australia
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16
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Cernusak LA, Ubierna N, Winter K, Holtum JAM, Marshall JD, Farquhar GD. Environmental and physiological determinants of carbon isotope discrimination in terrestrial plants. THE NEW PHYTOLOGIST 2013; 200:950-65. [PMID: 23902460 DOI: 10.1111/nph.12423] [Citation(s) in RCA: 232] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Accepted: 06/25/2013] [Indexed: 05/05/2023]
Abstract
Stable carbon isotope ratios (δ(13) C) of terrestrial plants are employed across a diverse range of applications in environmental and plant sciences; however, the kind of information that is desired from the δ(13) C signal often differs. At the extremes, it ranges between purely environmental and purely biological. Here, we review environmental drivers of variation in carbon isotope discrimination (Δ) in terrestrial plants, and the biological processes that can either damp or amplify the response. For C3 plants, where Δ is primarily controlled by the ratio of intercellular to ambient CO2 concentrations (ci /ca ), coordination between stomatal conductance and photosynthesis and leaf area adjustment tends to constrain the potential environmentally driven range of Δ. For C4 plants, variation in bundle-sheath leakiness to CO2 can either damp or amplify the effects of ci /ca on Δ. For plants with crassulacean acid metabolism (CAM), Δ varies over a relatively large range as a function of the proportion of daytime to night-time CO2 fixation. This range can be substantially broadened by environmental effects on Δ when carbon uptake takes place primarily during the day. The effective use of Δ across its full range of applications will require a holistic view of the interplay between environmental control and physiological modulation of the environmental signal.
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Affiliation(s)
- Lucas A Cernusak
- Department of Marine and Tropical Biology, James Cook University, Cairns, Qld, Australia
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17
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Wei L, Lockington DA, Poh SC, Gasparon M, Lovelock CE. Water use patterns of estuarine vegetation in a tidal creek system. Oecologia 2012; 172:485-94. [PMID: 23070143 DOI: 10.1007/s00442-012-2495-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2011] [Accepted: 09/29/2012] [Indexed: 10/27/2022]
Abstract
Water availability is a key determinant of the zonation patterns in estuarine vegetation, but water availability and the use of different water sources over space and time are not well understood. We have determined the seasonal water use patterns of riparian vegetation over an estuarine ecotone. Our aim was to investigate how the water use patterns of estuarine vegetation respond to variations in the availability of tidal creek water and rain-derived freshwater. The levels of natural stable isotopes of oxygen and hydrogen were assessed in the stem of the mangrove Avicennia marina (tall and scrub growth forms), Casuarina glauca and Melaleuca quinquenervia that were distributed along transects from river/creek-front towards inland habitats. The isotopic composition of plant tissues and the potential water sources were assessed in both the wet season, when freshwater from rainfall is present, and the dry season, when mangrove trees are expected to be more dependent on tidal water, and when Casuarina and Melaleuca are expected to be dependent on groundwater. Our results indicate that rainwater during the wet season contributes significantly to estuarine vegetation, even to creek-side mangroves which are inundated by tidal creek water daily, and that estuarine vegetation depends primarily on freshwater throughout the year. In contrast, high intertidal scrub mangroves were found to use the greatest proportion of tidal creek water, supplemented by groundwater in the dry season. Contrary to prediction, inland trees C. glauca and M. quinquenervia were found also to rely predominantly on rainwater--even in the dry season. The results of this study reveal a high level of complexity in vegetation water use in estuarine settings.
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Affiliation(s)
- Lili Wei
- National Centre for Groundwater Research and Training, Canberra, Australia.
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18
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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.
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Affiliation(s)
- Sebastian Pfautsch
- Faculty of Agriculture, Food and Natural Resources, University of Sydney, 1 Central Avenue, Eveleigh, NSW 2015, Australia.
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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)).
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Affiliation(s)
- Melanie Zeppel
- Plant Functional Biology and Climate Change Cluster and Department of Environmental Sciences, University of Technology, Sydney, NSW 2007, Australia
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20
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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.
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Affiliation(s)
- Jennifer L Carter
- CSIRO Sustainable Ecosystems, Centre for Environment and Life Sciences, Private Bag 5, Wembley, Western Australia 6913, Australia.
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21
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Bleby TM, Colquhoun IJ, Adams MA. Architectural plasticity in young Eucalyptus marginata on restored bauxite mines and adjacent natural forest in south-western Australia. TREE PHYSIOLOGY 2009; 29:1033-1045. [PMID: 19556233 DOI: 10.1093/treephys/tpp044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The aboveground architecture of Eucalyptus marginata (Jarrah) was investigated in chronosequences of young trees (2.5, 5 and 10 m height) growing in a seasonally dry climate in a natural forest environment with intact soils, and on adjacent restored bauxite mine sites on soils with highly modified A and B horizons above an intact C horizon. Compared to forest trees, trees on restored sites were much younger and faster growing, with straighter, more clearly defined main stems and deeper, narrower crowns containing a greater number of branches that were longer, thinner and more vertically angled. Trees on restored sites also had a higher fraction of biomass in leaves than forest trees, as indicated by 20-25% thicker leaves, 30-70% greater leaf area, 10-30% greater leaf area to sapwood area ratios and 5-30% lesser branch Huber values. Differences in crown architecture and biomass distribution were consistent with putatively greater soil-water, nutrient and light availability on restored sites. Our results demonstrate that under the same climatic conditions, E. marginata displays a high degree of plasticity of aboveground architecture in response to the net effects of resource availability and soil environment. These differences in architecture are likely to have functional consequences in relation to tree hydraulics and growth that, on larger scales, is likely to affect the water and carbon balances of restored forest ecosystems. This study highlights substrate as a significant determinant of tree architecture in water-limited environments. It further suggests that the architecture of young trees on restored sites may need to change again if they are to survive likely longer-term changes in resource availability.
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Affiliation(s)
- Timothy M Bleby
- School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia.
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O’Grady AP, Cook PG, Eamus D, Duguid A, Wischusen JDH, Fass T, Worldege D. Convergence of tree water use within an arid-zone woodland. Oecologia 2009; 160:643-55. [DOI: 10.1007/s00442-009-1332-y] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Accepted: 03/11/2009] [Indexed: 10/20/2022]
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Zeppel M, Macinnis-Ng C, Palmer A, Taylor D, Whitley R, Fuentes S, Yunusa I, Williams M, Eamus D. An analysis of the sensitivity of sap flux to soil and plant variables assessed for an Australian woodland using a soil-plant-atmosphere model. FUNCTIONAL PLANT BIOLOGY : FPB 2008; 35:509-520. [PMID: 32688807 DOI: 10.1071/fp08114] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Accepted: 06/10/2008] [Indexed: 06/11/2023]
Abstract
Daily and seasonal patterns of tree water use were measured for the two dominant tree species, Angophora bakeri E.C.Hall (narrow-leaved apple) and Eucalyptus sclerophylla (Blakely) L.A.S. Johnson & Blaxell (scribbly gum), in a temperate, open, evergreen woodland using sap flow sensors, along with information about soil, leaf, tree and micro-climatological variables. The aims of this work were to: (a) validate a soil-plant-atmosphere (SPA) model for the specific site; (b) determine the total depth from which water uptake must occur to achieve the observed rates of tree sap flow; (c) examine whether the water content of the upper soil profile was a significant determinant of daily rates of sap flow; and (d) examine the sensitivity of sap flow to several biotic factors. It was found that: (a) the SPA model was able to accurately replicate the hourly, daily and seasonal patterns of sap flow; (b) water uptake must have occurred from depths of up to 3 m; (c) sap flow was independent of the water content of the top 80 cm of the soil profile; and (d) sap flow was very sensitive to the leaf area of the stand, whole tree hydraulic conductance and the critical water potential of the leaves, but insensitive to stem capacitance and increases in root biomass. These results are important to future studies of the regulation of vegetation water use, landscape-scale behaviour of vegetation, and to water resource managers, because they allow testing of large-scale management options without the need for large-scale manipulations of vegetation cover.
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Affiliation(s)
- Melanie Zeppel
- Institute for Water and Environmental Resource Management and Department of Environmental Sciences, University of Technology, Sydney, NSW 2007, Australia
| | - Catriona Macinnis-Ng
- Institute for Water and Environmental Resource Management and Department of Environmental Sciences, University of Technology, Sydney, NSW 2007, Australia
| | - Anthony Palmer
- Institute for Water and Environmental Resource Management and Department of Environmental Sciences, University of Technology, Sydney, NSW 2007, Australia
| | - Daniel Taylor
- Institute for Water and Environmental Resource Management and Department of Environmental Sciences, University of Technology, Sydney, NSW 2007, Australia
| | - Rhys Whitley
- Institute for Water and Environmental Resource Management and Department of Environmental Sciences, University of Technology, Sydney, NSW 2007, Australia
| | - Sigfredo Fuentes
- Institute for Water and Environmental Resource Management and Department of Environmental Sciences, University of Technology, Sydney, NSW 2007, Australia
| | - Isa Yunusa
- Institute for Water and Environmental Resource Management and Department of Environmental Sciences, University of Technology, Sydney, NSW 2007, Australia
| | - Mathew Williams
- School of GeoSciences, University of Edinburgh, Edinburgh EH9 3JN, UK
| | - Derek Eamus
- Institute for Water and Environmental Resource Management and Department of Environmental Sciences, University of Technology, Sydney, NSW 2007, Australia
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Cernusak LA, Hutley LB, Beringer J, Tapper NJ. Stem and leaf gas exchange and their responses to fire in a north Australian tropical savanna. PLANT, CELL & ENVIRONMENT 2006; 29:632-46. [PMID: 17080613 DOI: 10.1111/j.1365-3040.2005.01442.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We measured stem CO2 efflux and leaf gas exchange in a tropical savanna ecosystem in northern Australia, and assessed the impact of fire on these processes. Gas exchange of mature leaves that flushed after a fire showed only slight differences from that of mature leaves on unburned trees. Expanding leaves typically showed net losses of CO2 to the atmosphere in both burned and unburned trees, even under saturating irradiance. Fire caused stem CO2 efflux to decline in overstory trees, when measured 8 weeks post-fire. This decline was thought to have resulted from reduced availability of C substrate for respiration, due to reduced canopy photosynthesis caused by leaf scorching, and to priority allocation of fixed C towards reconstruction of a new canopy. At the ecosystem scale, we estimated the annual above-ground woody-tissue CO2 efflux to be 275 g C m(-2) ground area year(-1) in a non-fire year, or approximately 13% of the annual gross primary production. We contrasted the canopy physiology of two co-dominant overstory tree species, one of which has a smooth bark on its branches capable of photosynthetic re-fixation (Eucalyptus miniata), and the other of which has a thick, rough bark incapable of re-fixation (Eucalyptus tetrodonta). Eucalyptus miniata supported a larger branch sapwood cross-sectional area in the crown per unit subtending leaf area, and had higher leaf stomatal conductance and photosynthesis than E. tetrodonta. Re-fixation by photosynthetic bark reduces the C cost of delivering water to evaporative sites in leaves, because it reduces the net C cost of constructing and maintaining sapwood. We suggest that re-fixation allowed leaves of E. miniata to photosynthesize at higher rates than those of E. tetrodonta, while the two invested similar amounts of C in the maintenance of branch sapwood.
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Affiliation(s)
- Lucas A Cernusak
- School of Science and Primary Industries, Faculty of Education, Health and Science, Charles Darwin University, Darwin, NT 0909, Australia.
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