The Choat Lab

Plant Hydraulics and Water Relations


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Field work at the Daintree Rainforest Observatory

Our research on the limits to the resilience of forests and woodlands to drought takes us to a range of native forests and woodlands across Australia. In late November, we visited one of the tropical field sites, Daintree Rainforest Observatory at Cape Tribulation, Far North Queensland. The DRO is a unique research facility, which can provide easy access to the rainforest canopy using a canopy crane gondola (47 m tall, 55 m radius). We studied the vulnerability of stems and leaves of rainforest tree species to drought and other related hydraulics parameters.

Daintree Rainforest Observatory (photo: MN) Sampling from the rainforest canopy, at the Daintree Rainforest Observatory (photo: MN) Dawn above the rainforest canopy (photo: MN)

The video below is a short time-lapse clip which was recorded during leaf sampling for anatomical analyses in the canopy, using the DRO canopy crane. Continue reading


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Visit from Herve Cochard

Herve, Rosana and Brendan at Mt Banks NP, NSW

Herve, Rosana and Brendan at Mt Banks, NSW

We were lucky enough to receive a visit from Dr Herve Cochard, aka “The General” of INRA. Herve, a world leader in plant hydraulics, is a close collaborator with the lab and a co-sponsor of Rosana’s Marie Curie Fellowship. Here we are at Mt Banks in the Blue Mountains NP, NSW.


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Hydraulic vulnerability analysis using X-ray microCT

One of the major points of critique for hydraulic measurements of xylem vulnerability and embolism is that they are destructive measurements. In contrast, non-invasive imaging has made it possible to observe xylem function and the spread of embolism in living, intact plants without destructive sampling and associated artefacts.

In collaboration with Iain Young and Richard Flavel at the University of New England, Armidale, we recently scanned the stems of young Eucalyptus trees at high resolution using X-ray Micro Computed Tomography (microCT) to visualize the loss of hydraulic function at increasing levels of drought. This allowed us to analyse the species’ vulnerability to drought-induced embolism, and validate hydraulic data using an independent, non-destructive method.

MicroCT cross section of a Eucalyptus stem in which air-filled areas appear darker than water-saturated tissues. From the centre outwards, you can see the central pith and primary xylem, followed by a ring of embolised vessels in the outer xylem area.

MicroCT cross section of a Eucalyptus stem.

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Paper: Leaf and stem hydraulics are finely coordinated in tropical rainforest trees

Water is one of the most limiting factors for terrestrial plant life. In dry conditions, hydraulic coordination of stems and leaves enables plants to maintain a safe water status and avoid hydraulic failure in the xylem. While such relationships have been shown for some tree species previously, little is known about hydraulic coordination in rainforest species which do not typically experience drought and represent a hydraulically understudied group of plants.

View across the daintree rainforest (photo: MN)

View across the daintree rainforest (photo: MN)

In our recent publication “Stem and leaf hydraulic properties are finely coordinated in three tropical rain forest tree species”, we studied plant hydraulics at the Daintree Rainforest Observatory in Far North Queensland and compared a number of hydraulic traits (including hydraulic vulnerability of stems and leaves, pressure-volume relations and in situ water potentials) in three tropical rain forest species. Continue reading


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Brendan Choat receives Thomson Reuters citation award for 2015

Brendan Choat was awarded a Thomson Reuters 2015 Citation and Innovation Award for 2015. In total, 11 Australian Research Groups were selected to receive Citation Awards in recognition of their outstanding contribution to research. In addition, 8 Australian organisations were recognised for their excellence in innovation. Brendan and his colleague A/Prof Tim Brodribb (University of Tasmania) received the citation award in Plant & Animal Science for their research in “Drought and tree mortalityā€¯. See full details at the Thomson Reuters site here.

ISI award choat

Brendan receiving his award with David Brown, (Global Head of Sales and Service for Thompson Reuters IP & Science) and Jeroen Prinsen (Senior Director at Thomson Reuters IP & Science)