Projects

Some current projects:

Interplay between leaf, stem and canopy traits and plant size on whole-plant growth rates

Growth rates are pivotal in vegetation ecology and a core element of plant ecological strategies. In this project we’re testing a range of hypotheses concerning the interplay of key functional traits (including tissue respiration rates) and biomass allometry in together determining growth outcomes, and how this varies with plant size. Our fieldwork has taken us from savannas in the Northern Territory, South Africa and Brazil, to tropical rainforest in Queensland.

  • Ian Wright, Emma Gray, Julia Cooke, Allyson Eller, Caroline Lehmann (U. Edinburgh), Lucas Cernusak (JCU).
  • Funded by Australian Research Council and Macquarie University.
  • Three manuscripts are now in prep. Check back for further details!
  • Ian and Emma are also part of a related project in which we ran a meta-analysis of trait-growth relationships in relation to plant size:
    • Gibert A, Gray EF, Westoby M, Wright IJ, Falster DS (2016). On the link between functional traits and growth rate: meta-analysis shows effects change with plant size, as predicted. Journal of Ecology 104: 1488-1503.

Understanding the anatomical, physiological, evolutionary and geographical underpinnings of variation in plant functional traits

A number of collaborative projects fall under this banner. Recent papers include:

  • Environmental drivers of leaf trait variation
    • Maire V, Wright IJ, Prentice IC, Batjes NH, Bhaskar R, van Bodegom PM, Cornwell WK, Ellsworth D, Niinemets Ü, Ordonez A, Reich PB, Santiago LS (2015). Global effects of soil and climate on leaf photosynthetic traits and rates. Global Ecology and Biogeography 24:706-717.
    • Miatto RC, Wright IJ & Batalha MA (2016). Relationships between soil nutrient status and nutrient-related leaf traits in Brazilian cerrado and seasonal forest communities. Plant & Soil 404: 13-33..
    • Global climatic controls on leaf size (Wright, Prentice, Westoby, Leishman et al in review).
    • Cornwell WK, Wright IJ, Turner J, Maire V, Barbour MM, Cernusak LA, Dawson T, Ellsworth D, Farquhar G, Griffiths H, Keitel C, Knohl A, Reich PB, Williams DG, Bhaskar R, Cornelissen JHC, Richards A, Schmidt S, Valladares F, Körner C, Schulze E-D, Buchmann N, Santiago L (in review). Climate and soils together regulate photosynthetic carbon isotope discrimination within C3 plants worldwide.
  • Ecological wood anatomy & hydraulics
    • Ziemińska K, Butler DW, Gleason SM, Wright IJ, Westoby M (2013). Fibre wall and lumen fractions drive wood density variation across 24 Australian angiosperms. AoB PLANTS 5:plt046. [link].
    • Richards AE, Wright IJ, Lenz TI, Zanne AE (2014). Sapwood capacitance is greater in woody plant species growing in high compared to low rainfall environments. Functional Ecology 28:734-744.
    • Ziemińska K, Westoby M, Wright IJ. 2015. Broad Anatomical Variation within a Narrow Wood Density Range—A Study of Twig Wood across 69 Australian Angiosperms. PLoS ONE 10: e0124892.
    • Gleason SM, Westoby M, Jansen S, Choat B et al (inc. IJ Wright) (2016). Weak tradeoff between xylem safety and xylem-specific hydraulic efficiency across the world’s woody plant species. New Phytologist 209:123-136.
  • Leaf traits and ecological strategies of paleo-species
    • Soh WK, Wright IJ, Bacon KL, Lenz TI, Steinthorsdottir M, McElwain JC (2017). Palaeo leaf economics reveal a shift in ecosystem function associated with the end-Triassic mass extinction event. Nature Plants 3:17104.
  • Global variation in plant traits
    • Cornwell W, Westoby M, Falster DS et al (inc IJ Wright) (2014). Functional distinctiveness of major plant lineages. Journal of Ecology 102:345-356.
    • Flores O, Garnier E, Wright IJ et al (2014). An evolutionary perspective on leaf economics in vascular plants: phylogenetic patterns in leaf mass per area. Ecology & Evolution 4:2799-2811.
    • Atkin O et al (inc. IJ Wright)(2015). Global variability in leaf respiration among plant functional types in relation to climate and leaf traits. New Phytologist 206:614-636.
    • Maire V, Wright IJ, Prentice IC, Batjes NH et al (2015). Global soil and climate effects on leaf photosynthetic traits and rates. Global Ecology & Biogeography 24:706-717.
    • Díaz S, Kattge J, Cornelissen JHC, Wright IJ, Lavorel S et al (2016). The global spectrum of plant form and function. Nature 529:167-171.
    • Cornwell WK, Wright IJ, Turner J, Maire V et al. A global dataset of leaf ∆13C values. (in review at Scientific Data).

Plant traits and ecological strategies in vegetation modelling

Over the last 20 years there has been huge growth in the availability of plant functional trait data, in research aimed at nailing down general trait relationships at regional to global scale, and in understanding how functional traits relate to plant ecological strategies. How best to take advantage of these advances? We have various projects which aim to build more “trait-strategy thinking” into vegetation and ecosystem process models, and to take better advantage of new data sources.

  • Working towards a “next-generation” dynamic global vegetation model. With Colin Prentice (Imperial College UK), Ian Wright, Wang Han, Yan-Shih Lin, Vincent Maire, Dong Ning and collaborators. Funded by Australian Research Council and Macquarie University.
    • Prentice IC, Dong N, Gleason SM, Maire V, Wright IJ (2014). Balancing the costs of carbon gain and water transport: testing a new theoretical framework for plant functional ecology. Ecology Letters 17:82-91.
    • Wang H, Prentice IC, Davis TW (2014). Biophysical constraints on gross primary production by the terrestrial biosphere. Biogeosciences 11:5987-6001.
    • De Kauwe MG, Lin Y-S, Wright IJ, Medlyn BE , Crous KY, Ellsworth DS, Maire V, Prentice IC, Atkin OK, Rogers A, Niinemets Ü, Serbin SP, Meir P, Uddling J, Togashi HF, Tarvainen L, Weerasinghe LK, Evans BJ, Ishida FY & Domingues TF (2016). A test of the ‘one-point method’ for estimating maximum carboxylation capacity from field-measured, light-saturated photosynthesis. New Phytologist 210:1130-44.
    • Dong N, Prentice IC, Evans B, Caddy-Retalic S, Lowe A, Wright IJ (2017). Leaf nitrogen from first principles: field evidence for adaptive variation with climate. Biogeosciences 14:481-495.
    • Wang H, Prentice IC, Davis TW, Keenan TF, Wright IJ, Peng C (2017). Photosynthetic responses to altitude: an explanation based on optimality principles. New Phytologist 213:976-982.
    • Wang H, Prentice IC, Cornwell WK, Keenan TF, Davis TW, Wright IJ, Evans BJ, Peng C (in review). A universal model for carbon dioxide uptake by plants. Nature Plants (accepted).
  • Introducing “trait-thinking” into the CABLE land surface model. With Ying-Ping Wang (CSIRO), Chris Lu (CSIRO), Ian Wright, Yongjiu Dai, Peter Reich.
    • Wang YP, Lu XJ, Wright IJ, Dai YJ, Rayner PJ, Reich PB (2012). Correlations among leaf traits provide a significant constraint on the estimate of global gross primary production. Geophysical Research Letters 39:L19405.
    • Lu XJ, Wang YP, Wright IJ, Reich PB, Shi Z, Dai YJ (2016). Incorporation of plant traits in a land surface model helps explain the global biogeographical distribution of major forest functional types. Global Ecology & Biogeography 26:304-317.

Comparative ecophysiology of Australian and Brazilian mistletoe-host relationships

The association between mistletoes and their hosts is a fascinating co-evolutionary system. Mistletoes are parasitic angiosperms that connect to the host branch and acquire water and nutrients exclusively via the host xylem. We argue that these hemi-parasites should differ from their hosts in the per-unit acquisition and maintenance costs of resources, affecting leaf trait relationships and adaptations to environmental constraints. We are testing a range of hypotheses concerning ecological strategies in mistletoes compared to their hosts in relation to water use, nutrient concentration, photosynthetic and respiration rates, leaf life span and other traits. This will help us to identify general relationships among leaf traits, and the influence of different environmental conditions on traits, trait relationships and ecological strategies. Our sampling has been spread across a range of distinct habitats, from deserts to forests, and within Australia and Brazil.

  • Marina Scalon, Ian Wright
  • Funded by National Council for Scientific and Technological Development, Brazil (CNPq), and Macquarie University.
    • Scalon MC, Wright IJ (2015). A global analysis of water and nitrogen relationships between mistletoes and their hosts: broad-scale tests of old and enduring hypotheses. Functional Ecology 29:1114-1124.
    • Scalon MC, Wright IJ, Franco AC (2017). To recycle or steal? Nutrient resorption in Australian and Brazilian  mistletoes from three low-phosphorus sites. Oikos 126:32-39.
    • Scalon MC & Wright IJ (2017). Photosynthetic trait adaptations of parasitic mistletoes and their hosts in sites of contrasting aridity. Plant & Soil, accepted.

Flammability traits and decomposition

Litter on the forest floor can be decomposed or burned. Both pathways are dependent on environmental conditions and litter quality. At the same time, both decomposition and fire influence mineralization rates. Hence, there seems to be a strong relationship between these two fates, fire and decomposition. Which plant traits are most important in explaining a vegetation’s flammability? Do species properties matter, and if so, how? To which extent are species’ inherent flammability and litter decomposability coupled? With this information we could improve global vegetation models and make more reliable predictions about future shifts in vegetation and fire regimes in relation to climate change.

  • Saskia Grootemaat, Ian Wright, Hans Cornelissen and Peter van Bodegom (Vrije University, Amsterdam).
    • Grootemaat S, Wright IJ, van Bodegom PM, Cornelissen JHC, Cornwell WK (2015). Burn or rot: different roles of leaf traits in fire versus decomposition. Functional Ecology 29:1486-1497.
    • Grootemaat S, Wright IJ, van Bodegom PM, Cornelissen JHC (2017). Scaling up flammability from individual leaves to fuel beds. Oikos DOI: 10.1111/oik.03886.
    • Grootemaat S, Wright IJ, van Bodegom PM, Cornelissen JHC, Shaw V (2017). Bark traits, decomposition and flammability of Australian forest trees. Australian Journal of Botany 65:327-338.

Plant biogeography based on functional traits

Biogeography is the study of where species live and why – their distribution across geographic space and through geological time. In this project, we will analyse biogeographic patterns of plant strategy variation by combining data on plant traits with information on species distributions. Specifically, we aim to create Australia’s largest database of plant traits, couple this information to distribution data in Australia’s Virtual Herbarium and use the resulting dataset to explore questions about range limits, trait variation and ecological strategies, and the role of climate and edaphic factors play in mediating them.

  • Rachael Gallagher, Ian Wright
  • Funded by Macquarie University Research Fellowship (Gallagher).

 

Ecology meets ‘omics: population-level variation in molecular thermotolerance traits under extreme heat 

Using the first sequenced Eucalyptus species, E. grandis, we are using a proteomics approach to quantify the molecular mechanisms responsible for heat tolerance in this species. Severe heatwaves in Australia have the potential to greatly affect organism functioning and are expected to increase in frequency and severity under climate change. Plants being sessile have to rely on molecular traits to avert cellular damage under such conditions. Seedlings are particularly reliant on such traits for survival under heat stress. To predict the vulnerability of a species’ seedlings to such events, it is necessary to identify the adaptive diversification in these traits among wild provenances. To determine this level of variation in thermotolerance traits in E.grandis, we are conducting a manipulative heat experiment using E.grandis seedlings drawn from provenances along a gradient of increasing average temperature on the East Coast of Australia.

  • Timothy Maher (Master Research student), Rachael Gallagher, Mehdi Merzai, Ian Wright
  • Funded by Macquarie University Research Fellowship (Gallagher), and Macquarie University.

Early detection and surveillance of Myrtle Rust

Myrtle rust (Puccinia psidii) is a plant pathogenic fungus that was introduced accidently into Australia (NSW) in 2010 and has since spread along the east coast, from Tasmania to the Northern Territory, attacking plant species in the family Myrtaceae, both in natural vegetation and in commercially-important plantations. Myrtle Rust has been listed as a Key Threatening Process under the NSW Threatened Species Conservation Act. In this project we will characterise the spectral signal of Myrtle Rust infestations, with a view to developing ‘proof of concept’ for a low-cost, drone-based system for early detection and surveillance of this potentially devastating disease.

  • Rene Heim (PhD student, jointly enrolled at Macquarie and U. Hamburg), Ian Wright, Michelle Leishman, Jens Oldeland (Hamburg), Angus Carnegie (NSW Department of Primary Industries)

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