PhD Scholarship Available: Modelling Optimal Plant Behaviour, or Do Plants Hedge Their Bets?
We currently have a PhD scholarship available for a bright, mathematically oriented student to work on an ARC Discovery Project. The project aims to resolve one of the most long-standing questions about the functioning of plants: how much of the carbon that they take up in photosynthesis do they use immediately for growth, and how much do they keep in reserve as insurance for the future? The answer to this question is urgently needed to understand how plants respond to environmental change, and how vulnerable they are to stresses such as drought.
The student will benefit from the superlative research environment here at HIE and will also work with our outstanding collaborators, Roderick Dewar at ANU and Mat Williams at Edinburgh University (UK). The scholarship is open to international candidates. The project involves optimisation techniques such as calculus of variations so the student must have a good maths background. I strongly encourage women with this background to apply.
More information here or please email me: b.medlyn – at – westernsydney.edu.au
Closing date: 5 February 2017
We’re welcoming our new post-doc Mingkai Jiang, who comes to us from Lehigh University in the US. It’s a great pleasure to have you join us Mingkai!
In journal club last year we read Michaletz et al. (2014) “Convergence of terrestrial plant production across global climate gradients” Nature doi:10.1038/nature13470 along with the critique by Chu et al. (2015) in Global Change Biology.
The paper tests whether Net Primary Production (NPP) is more strongly related to climate or to stand biomass and age, using a dataset of NPP compiled from a number of sources. We found it a bit odd that about 90% of the 1200 entries in the dataset came from just one source – a Chinese PhD thesis from 1996. PhD student Jim Yang downloaded the thesis and translated the relevant bits and we realised that the “data” were not measured at all, but modelled as a function of stand biomass and age. Clearly such “data” cannot be used to test for relationships with biomass and age.
To their credit, Michaletz et al. responded rapidly when we emailed them about this issue (that can’t have been a nice email to receive!) They submitted a correction to Nature in early January and it has finally been published, along with a revised version of their dataset which contains just 138 entries.
The debate over the analysis by Michaletz et al. will no doubt continue (see Chu et al. 2015) but at least it can now do so with a considerably less flawed dataset. A win for journal club!
Our new paper in Nature Scientific Reports shows that patterns of stomatal behaviour around the world have surprising ramifications for global climate. Previously our ecosystem modelling group showed clear differences in stomatal behaviour among plant functional types, based on datasets contributed by collaborators around the globe (Lin et al. 2015 Nature Climate Change). Now working with climate modellers, we find that these differences in leaf-level stomatal behaviour imply differences in ecosystem-scale water use – with major consequences for land surface temperatures and the number of heatwaves in future. Heatwaves in the northern hemisphere in the middle of this century may be up to 5 degrees C higher than previously estimated. There is media coverage at phys.org and the Sydney Morning Herald or you can read the full paper (open access) here:
Nature Scientific Reports “Impact of the representation of stomatal conductance on model projections of heatwave intensity” (Jatin Kala, Martin G. De Kauwe, Andy J. Pitman, Belinda E. Medlyn, Ying-Ping Wang, Ruth Lorenz & Sarah E. Perkins-Kirkpatrick)
We were very happy to have been successful in the latest ARC Discovery round! Our project is entitled “To grow or to store: do plants hedge their bets?” and will investigate a long-standing question about the function of perennial plants: how much of the carbon taken up by photosynthesis is used immediately for growth, and how much is kept in reserve as insurance against future stress? My co-CI’s are Remko Duursma (HIE), Roddy Dewar (Australian National University) and Mat Williams (University of Edinburgh).
Teresa Gimeno’s recent paper on stomatal behaviour at EucFACE received page 5 coverage in Saturday’s Weekend Australian. The paper finds that instantaneous water-use efficiency increases in proportion to the CO2 concentration, or in layman’s terms “Either they use the same amount of water but they do more photosynthesis, or they do the same amount of photosynthesis but use less water”. I was pleased to see that the reporter, John Ross, was careful to include my caveats: “Professor Medlyn stressed that the experiment had analysed extra CO2 only “at the leaf scale”, with more work needed to observe the effects on whole plants and communities. Hotter conditions would probably cancel out benefits of higher CO2.”
We are currently advertising for a three-year postdoctoral position in Terrestrial Ecosystem Modelling. http://j.mp/HIE-Modeller The aim of this position is help us develop a new vegetation model focused on Australian woody ecosystems, capitalising on the amazing datasets available here at HIE. It’s a great opportunity! Please contact me for further information.