Research

An overview of current and recent research projects

My research revolves around understanding vegetation and function with models and data. I develop models of plant ecophysiological processes such as plant water use, stomatal conductance and photosynthesis, canopy architecture and light interception, biomass allocation and growth. This work is done with many collaborators, read about a few of them here.

Besides developing models, I have a strong focus on data synthesis and analysis. You can read about examples of this kind of work in the projects below, or browse through my publications. As a result of various data analysis projects, I aim to share code in the hope that it may be useful to others.

The Biomass And Allometry Database.

In a project led by Daniel Falster at Macquarie University, we have compiled the largest database of plant biomass data so far. We have taken the unusual step to publish the data before any analysis papers were even submitted, as a data paper in Ecology. You can also view the slides of my recent presentation (ESA, Baltimore, 2015) on slideshare here. The process of combining data from nearly 200 sources is no easy task, and Daniel has written a nice blog post about the challenges and solutions.

Stomatal behaviour

As part of an ARC Discovery project (ended 2014), Belinda Medlyn, myself, and collaborators have studied the trade-off between carbon uptake and water use by plants. For every mole of CO2 taken up by plants,300-400 moles of H2O are lost. The stomata regulate this exchange, and it has been proposed that stomata optimize carbon uptake at a given amount of water use. We have applied this theory, and found it describes well the response of water-use efficiency to elevated CO2, air humidity, temperature and light. We have also synthesized data describing stomatal behaviour across the globe (read about it here). Browse through our list of papers on the subject here.

EucFACE

I am involved with a Free-Air CO2 Enrichment (FACE) study in a Eucalyptus woodland, the EucFACE. Read all about the experiment here. I lead a project at the EucFACE on monitoring of canopy leaf area index and greenness, using light sensors and images from automated cameras. I am also involved in an ecosystem modelling project, where we try to improve the dialogue between experimental data and model application (see our recent paper authored by Rich Norby).

Whole-tree chambers

I have been involved with the whole-tree chamber experiment since 2008. Currently the experiment is coordinated by Prof. Mark Tjoelker. The experiment consists of twelve 10m tall climate-controlled chambers, and have been subjected to treatments of CO2, warming, and drought (in three different experiments sofar). The chambers measure whole-tree fluxes of CO2 and H2O every 15min. We have used these data to understand response of water-use efficiency to CO2 (Barton et al. 2012), the peculiar response of tree water use to air humidity and temperature (Duursma et al. 2014), and the interaction between tree size and sensitivity to drought via the rooting depth (Duursma et al. 2011).

Wheat response to CO2 and heat waves

As part of a DAFF-funded project (lead: Michael Tausz, Melbourne University), Oula Ghannoum and I, together with Phd student Sachin Chavan, are working on understanding effects of elevated CO2 and heat waves on photosynthesis and productivity of wheat. The main challenge is to develop a method to model effects of heat waves and its interactions with CO2 for use in crop models.

Tree mortality in response to drought

This ARC Linkages project led by Belinda Medlyn attempts to identify regions of New South Wales that are sensitive to drought-induced tree mortality. We (a large multi-institutional team) are combining ecophysiological experiments, process-based modelling, species distribution models and remote sensing methods. As part of this project I am further developing MAESPA to aid in understanding the mechanisms of drought-related decline and mortality in trees.