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Ms Audrey Quentin

profile_quentin_thumbMs Audrey Quentin
PhD student

Topic: whole tree physiological responses to multiple stress events and their interaction

University of Tasmania

I moved to Australia from France for the first time in 2005 to undertake a six-month Honours project, researching the impacts on eucalypt physiology of the fungal diseases Mycosphaerella sp. and Phaeophleoposra eucalypti. The people I worked with were extremely helpful in assisting me with my research topic and keeping me happy over those six months. I felt I gained a huge amount of benefit and knowledge in the field of forest health and sustainable management by doing that project with the CRC for Forestry. So after graduating with Honours in Agricultural Sciences at the School of Agricultural, Environmental and Food Sciences (ESITPA) in Rouen, Normandy, I was in a position to commence a PhD project with the Forest Health Group of the CRC for Forestry, and I began my project in July 2006.

This project explores the impact of tree defoliation, compounded with other stress events, generating additional physiological responses by the tree. Defoliation from insect or disease attack is a common forest health issue in eucalypt plantations that can affect the trees’ capacity for carbon dioxide uptake, and therefore growth. Understanding the effect of defoliation on tree resources (sunlight, photosynthesis and energy production; water and nutrient uptake) and consequently on the physiology and shape of tree crowns can be helpful in the development of computer models that explain the functioning of forest stands (a useful tool for forest managers).

The project seeks to quantify the relationship between whole tree physiology and defoliation associated with insect or disease damage in order to be able to predict the interactive effects of defoliation and other stresses upon plantation productivity. A working hypothesis for this project is that plants already under water stress seek to maintain current rates of physiological activity and carbon uptake if confronted with pest defoliation.

In the initial stage of the project I will explore the response from individual trees that I will submit to stress during an experiment where the crown is artificially defoliated (in a plot trial, I will snip the leaves by hand). The aim is to investigate whether defoliation changes the efficiency of photosynthesis and water transport in the stem and leaf. Next, I will explore the response of eucalypt seedlings to insect-caused defoliation, particularly how these responses affect plant growth.

My supervisors are Associate Professor Caroline Mohammed (University of Tasmania and CSIRO Forest Biosciences (CFB)), Dr Libby Pinkard (CFB), Dr Chris Beadle (CFB), and Dr Tony O'Grady (University of Tasmania).

This research is funded by an international scholarship from the University of Tasmania with a top-up from the CRC for Forestry.

My PhD studies contribute to the Managing and Sustaining research project of the CRC for Forestry.

To browse other PhD projects available with the Managing and Monitoring for Growth and Health Research Programme click here.


Defoliation effects on Eucalyptus globulus physiology and interactions with water deficit
Presentation by PhD student Audrey Quentin to visiting Chinese scientists, 11 June 2008. [pdf 1.7 Mb]

Physiological capacity of Eucalyptus globulus. Labill to recover following moderate defoliation
Poster presented by PhD student Audrey Quentin at IUFRO meeting: natural enemies and other multi-scale influences on forest insects, September 2007. [pdf 203.4 kb]