School of Agriculture, Food and Ecosystem Sciences - Research Publications

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    Can we integrate ecological approaches to improve plant selection for green infrastructure?
    Farrell, C ; Livesley, SJ ; Arndt, SK ; Beaumont, L ; Burley, H ; Ellsworth, D ; Esperon-Rodriguez, M ; Fletcher, TD ; Gallagher, R ; Ossola, A ; Power, SA ; Marchin, R ; Rayner, JP ; Rymer, PD ; Staas, L ; Szota, C ; Williams, NSG ; Leishman, M (ELSEVIER GMBH, 2022-10)
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    Selecting tree species with high transpiration and drought avoidance to optimise runoff reduction in passive irrigation systems
    Thom, JK ; Livesley, SJ ; Fletcher, TD ; Farrell, C ; Arndt, SK ; Konarska, J ; Szota, C (ELSEVIER, 2022-03-15)
    Rainfall in cities can generate large volumes of stormwater runoff which degrades receiving waterways. Irrigating trees with runoff (passive irrigation) has the potential to increase transpiration and contribute to stormwater management by reducing runoff received by downstream waterways, but the stochastic nature of rainfall may expose trees with high transpiration to drought stress. We hypothesized that for success in passive irrigation systems, tree species should exhibit i) high maximum transpiration rates under well-watered conditions, ii) drought avoidance between rainfall events, and iii) high recovery of transpiration with rainfall following a drought. We assessed 13 commonly planted urban tree species in Melbourne, Australia against three metrics representing these behaviours (crop factor, hydroscape area, and transpiration recovery, respectively) in a glasshouse experiment. To aid species selection, we also investigated the relationships between these three metrics and commonly measured plant traits, including leaf turgor loss point, wood density, and sapwood to leaf area ratio (Huber value). Only one species (Tristaniopsis laurina) exhibited a combination of high crop factor (>1.1 mm mm-1 d-1) indicating high transpiration, small hydroscape area (<3 MPa2) indicating drought avoidance, and high transpiration recovery (>85%) following water deficit. Hence, of the species measured, it had the greatest potential to reduce runoff from passive irrigation systems while avoiding drought stress. Nevertheless, several other species showed moderate transpiration, hydroscape areas and transpiration recovery, indicating a balanced strategy likely suitable for passive irrigation systems. Huber values were negatively related to crop factor and transpiration recovery and may therefore be a useful tool to aid species selection. We propose that selecting tree species with high transpiration rates that can avoid drought and recover well could greatly reduce stormwater runoff, while supporting broader environmental benefits such as urban cooling in cities.
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    Tree water-use strategies to improve stormwater retention performance of biofiltration systems
    Szota, C ; McCarthy, MJ ; Sanders, GJ ; Farrell, C ; Fletcher, TD ; Arndt, SK ; Livesley, SJ (PERGAMON-ELSEVIER SCIENCE LTD, 2018-11-01)
    Biofiltration systems are highly valued in urban landscapes as they remove pollutants from stormwater runoff whilst contributing to a reduction in runoff volumes. Integrating trees in biofilters may improve their runoff retention performance, as trees have greater transpiration than commonly used sedge or herb species. High transpiration rates will rapidly deplete retained water, creating storage capacity prior to the next runoff event. However, a tree with high transpiration rates in a biofilter system will likely be frequently exposed to drought stress. Selecting appropriate tree species therefore requires an understanding of how different trees use water and how they respond to substrate drying. We selected 20 tree species and quantified evapotranspiration (ET) and drought stress (leaf water potential; Ψ) in relation to substrate water content. To compare species, we developed metrics which describe: (i) maximum rates of ET under well-watered conditions, (ii) the sensitivity of ET and (iii) the response of Ψ to declining substrate water content. Using these three metrics, we classified species into three groups: risky, balanced or conservative. Risky and balanced species showed high maximum ET, whereas conservative species always had low ET. As substrates dried, the balanced species down-regulated ET to delay the onset of drought stress; whereas risky species did not. Therefore, balanced species with high ET are more likely to improve the retention performance of biofiltration systems without introducing significant drought risk. This classification of tree water use strategies can be easily integrated into water balance models and improve tree species selection for biofiltration systems.
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    AusTraits, a curated plant trait database for the Australian flora
    Falster, D ; Gallagher, R ; Wenk, EH ; Wright, IJ ; Indiarto, D ; Andrew, SC ; Baxter, C ; Lawson, J ; Allen, S ; Fuchs, A ; Monro, A ; Kar, F ; Adams, MA ; Ahrens, CW ; Alfonzetti, M ; Angevin, T ; Apgaua, DMG ; Arndt, S ; Atkin, OK ; Atkinson, J ; Auld, T ; Baker, A ; von Balthazar, M ; Bean, A ; Blackman, CJ ; Bloomfeld, K ; Bowman, DMJS ; Bragg, J ; Brodribb, TJ ; Buckton, G ; Burrows, G ; Caldwell, E ; Camac, J ; Carpenter, R ; Catford, J ; Cawthray, GR ; Cernusak, LA ; Chandler, G ; Chapman, AR ; Cheal, D ; Cheesman, AW ; Chen, S-C ; Choat, B ; Clinton, B ; Clode, PL ; Coleman, H ; Cornwell, WK ; Cosgrove, M ; Crisp, M ; Cross, E ; Crous, KY ; Cunningham, S ; Curran, T ; Curtis, E ; Daws, M ; DeGabriel, JL ; Denton, MD ; Dong, N ; Du, P ; Duan, H ; Duncan, DH ; Duncan, RP ; Duretto, M ; Dwyer, JM ; Edwards, C ; Esperon-Rodriguez, M ; Evans, JR ; Everingham, SE ; Farrell, C ; Firn, J ; Fonseca, CR ; French, BJ ; Frood, D ; Funk, JL ; Geange, SR ; Ghannoum, O ; Gleason, SM ; Gosper, CR ; Gray, E ; Groom, PK ; Grootemaat, S ; Gross, C ; Guerin, G ; Guja, L ; Hahs, AK ; Harrison, MT ; Hayes, PE ; Henery, M ; Hochuli, D ; Howell, J ; Huang, G ; Hughes, L ; Huisman, J ; Ilic, J ; Jagdish, A ; Jin, D ; Jordan, G ; Jurado, E ; Kanowski, J ; Kasel, S ; Kellermann, J ; Kenny, B ; Kohout, M ; Kooyman, RM ; Kotowska, MM ; Lai, HR ; Laliberte, E ; Lambers, H ; Lamont, BB ; Lanfear, R ; van Langevelde, F ; Laughlin, DC ; Laugier-kitchener, B-A ; Laurance, S ; Lehmann, CER ; Leigh, A ; Leishman, MR ; Lenz, T ; Lepschi, B ; Lewis, JD ; Lim, F ; Liu, U ; Lord, J ; Lusk, CH ; Macinnis-Ng, C ; McPherson, H ; Magallon, S ; Manea, A ; Lopez-Martinez, A ; Mayfeld, M ; McCarthy, JK ; Meers, T ; van der Merwe, M ; Metcalfe, DJ ; Milberg, P ; Mokany, K ; Moles, AT ; Moore, BD ; Moore, N ; Morgan, JW ; Morris, W ; Muir, A ; Munroe, S ; Nicholson, A ; Nicolle, D ; Nicotra, AB ; Niinemets, U ; North, T ; O'Reilly-Nugent, A ; O'Sullivan, OS ; Oberle, B ; Onoda, Y ; Ooi, MKJ ; Osborne, CP ; Paczkowska, G ; Pekin, B ; Pereira, CG ; Pickering, C ; Pickup, M ; Pollock, LJ ; Poot, P ; Powell, JR ; Power, S ; Prentice, IC ; Prior, L ; Prober, SM ; Read, J ; Reynolds, V ; Richards, AE ; Richardson, B ; Roderick, ML ; Rosell, JA ; Rossetto, M ; Rye, B ; Rymer, PD ; Sams, M ; Sanson, G ; Sauquet, H ; Schmidt, S ; Schoenenberger, J ; Schulze, E-D ; Sendall, K ; Sinclair, S ; Smith, B ; Smith, R ; Soper, F ; Sparrow, B ; Standish, RJ ; Staples, TL ; Stephens, R ; Szota, C ; Taseski, G ; Tasker, E ; Thomas, F ; Tissue, DT ; Tjoelker, MG ; Tng, DYP ; de Tombeur, F ; Tomlinson, K ; Turner, NC ; Veneklaas, EJ ; Venn, S ; Vesk, P ; Vlasveld, C ; Vorontsova, MS ; Warren, CA ; Warwick, N ; Weerasinghe, LK ; Wells, J ; Westoby, M ; White, M ; Williams, NSG ; Wills, J ; Wilson, PG ; Yates, C ; Zanne, AE ; Zemunik, G ; Zieminska, K (NATURE PORTFOLIO, 2021-09-30)
    We introduce the AusTraits database - a compilation of values of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 448 traits across 28,640 taxa from field campaigns, published literature, taxonomic monographs, and individual taxon descriptions. Traits vary in scope from physiological measures of performance (e.g. photosynthetic gas exchange, water-use efficiency) to morphological attributes (e.g. leaf area, seed mass, plant height) which link to aspects of ecological variation. AusTraits contains curated and harmonised individual- and species-level measurements coupled to, where available, contextual information on site properties and experimental conditions. This article provides information on version 3.0.2 of AusTraits which contains data for 997,808 trait-by-taxon combinations. We envision AusTraits as an ongoing collaborative initiative for easily archiving and sharing trait data, which also provides a template for other national or regional initiatives globally to fill persistent gaps in trait knowledge.
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    Does the turgor loss point characterize drought response in dryland plants?
    Farrell, C ; Szota, C ; Arndt, SK (WILEY, 2017-08)
    The water potential at turgor loss point (Ψtlp ) has been suggested as a key functional trait for determining plant drought tolerance, because of its close relationship with stomatal closure. Ψtlp may indicate drought tolerance as plants, which maintain gas exchange at lower midday water potentials as soil water availability declines also have lower Ψtlp . We evaluated 17 species from seasonally dry habitats, representing a range of life-forms, under well-watered and drought conditions, to determine how Ψtlp relates to stomatal sensitivity (pre-dawn water potential at stomatal closure: Ψgs0 ) and drought strategy (degree of isohydry or anisohydry; ΔΨMD between well-watered conditions and stomatal closure). Although Ψgs0 was related to Ψtlp , Ψgs0 was better related to drought strategy (ΔΨMD ). Drought avoiders (isohydric) closed stomata at water potentials higher than their Ψtlp ; whereas, drought tolerant (anisohydric) species maintained stomatal conductance at lower water potentials than their Ψtlp and were more dehydration tolerant. There was no significant relationship between Ψtlp and ΔΨMD . While Ψtlp has been related to biome water availability, we found that Ψtlp did not relate strongly to stomatal closure or drought strategy, for either drought avoiders or tolerators. We therefore suggest caution in using Ψtlp to predict vulnerability to drought.
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    High water users can be drought tolerant: using physiological traits for green roof plant selection
    Farrell, C ; Szota, C ; Williams, NSG ; Arndt, SK (SPRINGER, 2013-11)
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    Phenotypic Plasticity of Drought Tolerance Traits in a Widespread Eucalypt (Eucalyptus obliqua)
    Pritzkow, C ; Szota, C ; Williamson, VG ; Arndt, SK (MDPI, 2020-12)
    Long-term studies of tree responses to drought stress help us to understand the capacity of species to adapt to their environment. In this study, we investigated how Eucalyptus obliqua adjusts physiological and morphological traits in response to seasonal and multi-year droughts. We monitored physiological and morphological traits over multiple years in undisturbed control and throughfall reduction plots in a eucalypt forest in south-eastern Australia. The throughfall reduction treatment did not induce significantly lower soil moisture in the throughfall reduction plots compared with the control plots. However, natural variability in precipitation and evaporative demand induced drought stress of varying intensity each summer in all plots. We observed a significant relationship between seasonal precipitation and leaf pre-dawn water potential (ΨPD), with less precipitation over summer, resulting in a decline in ΨPD and drought stress when ΨPD fell below −0.75 MPa. Eucalyptus obliqua responded to short-term summer drought through rapid leaf osmotic adjustment which lowered the leaf water potential at the turgor loss point beyond the minimum leaf water potential. Morphological adjustments, such as the reduction of leaf area to sapwood area (higher Huber Value) were moderate during the measurement period and only occurred under severe drought stress (pre-dawn water potential < −1.2 MPa). Overall, E. obliqua responded to short-term mild drought stress through physiological trait plasticity, while morphological adjustment only occurred under a more severe water deficit.
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    Phenotypic plasticity and genetic adaptation of functional traits influences intra-specific variation in hydraulic efficiency and safety
    Pritzkow, C ; Williamson, V ; Szota, C ; Trouve, R ; Arndt, SK ; Martinez-Vilalta, J (OXFORD UNIV PRESS, 2020-02)
    Understanding which hydraulic traits are under genetic control and/or are phenotypically plastic is essential in understanding how tree species will respond to rapid shifts in climate. We quantified hydraulic traits in Eucalyptus obliqua L'Her. across a precipitation gradient in the field to describe (i) trait variation in relation to long-term climate and (ii) the short-term (seasonal) ability of traits to adjust (i.e., phenotypic plasticity). Seedlings from each field population were raised under controlled conditions to assess (iii) which traits are under strong genetic control. In the field, drier populations had smaller leaves with anatomically thicker xylem vessel walls, a lower leaf hydraulic vulnerability and a lower water potential at turgor loss point, which likely confers higher hydraulic safety. Traits such as the water potential at turgor loss point and ratio of sapwood to leaf area (Huber value) showed significant adjustment from wet to dry conditions in the field, indicating phenotypic plasticity and importantly, the ability to increase hydraulic safety in the short term. In the nursery, seedlings from drier populations had smaller leaves and a lower leaf hydraulic vulnerability, suggesting that key traits associated with hydraulic safety are under strong genetic control. Overall, our study suggests a strong genetic control over traits associated with hydraulic safety, which may compromise the survival of wet-origin populations in drier future climates. However, phenotypic plasticity in physiological and morphological traits may confer sufficient hydraulic safety to facilitate genetic adaptation.
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    Urban Plantings: 'Living Laboratories' for Climate Change Response
    Farrell, C ; Szota, C ; Arndt, SK (ELSEVIER SCIENCE LONDON, 2015-10)
    Urban plantings are not only valuable resources for understanding 'urban plant physiology' but are 'living laboratories' for understanding plant response to climate change. Therefore, we encourage researchers who currently work in natural ecosystems to consider how urban plantings could enhance their research into plant physiological responses to a changing climate.