Graduated PhD 2019
Hydraulic Vulnerability of Australian Forests to Drought
With current and future climate change resulting in increased temperatures and drought frequency, it is critically important to understand and predict physiological thresholds affecting tree mortality. Drought-induced tree mortality has the potential to impact species distributions, forest community structure, and associated ecosystem services with potential feedbacks to ecosystem hydrology. Plant hydraulic limitations have been identified as key traits contributing to forest mortality in a warmer, dryer climate.
My research is focused on characterizing hydraulic coordination and limitations in woody plant species from forests and woodland ecosystems across Australia, with the goal of understanding the vulnerability of Australian forests to drought. Australian forests provide the ideal study system for this research, spanning a wide geographic and climatic range. As well, Australian plant species are underrepresented in an ever-growing global database of plant hydraulic traits. The Terrestrial Ecological Research Network (TERN) will serve as the platform for this research, with representative Supersites located in wooded ecosystems across Australia. At each site, I measure key hydraulic traits for the dominant tree species, including vulnerability to embolism (the primary mechanism of hydraulic failure) of both leaves and stems.
Current water status from seasonal in situ water potential measurements, in conjunction with measures of vulnerability to drought-induced embolism, will be used to indicate the current and future risk of drought-induced hydraulic failure and tree mortality. Comparisons of key hydraulic traits within and across species will allow for the identification of possible coordination of plant organs (i.e. leaf and xylem tissues) and the employment of preservation strategies whereby xylem tissue may be protected by the sacrifice of less costly leaf tissues. This project will employ a wide array of techniques for measuring drought vulnerability, including time-lapse photography of embolisms within leaves and psychrometers for continuous measurements of water stress in leaves and stem tissue, contributing to the development of best-practice techniques for assessment of hydraulic function in Australian tree species.
This research aims to improve our understanding of forest vulnerability to drought; clearly defining hydraulic limits across Australian native tree species and contributing to efforts toward process-based representation of hydraulic function in terrestrial ecosystem models.
Choat B, Nolf M, Lopez R, Peters JMR, Carins-Murphy MR, Creek D, Brodribb TJ, (2019) 'Non-invasive imaging shows no evidence of embolism repair after drought in tree species of two genera', Tree physiology, vol.39, no.1, pp 113-121
Li XM, Blackman CJ, Peters JMR, Choat B, Rymer PD, Medlyn BE, Tissue DT, (2019) 'More than iso/anisohydry: Hydroscapes integrate plant water use and drought tolerance traits in 10 eucalypt species from contrasting climates', Functional Ecology, vol.33, no.6, pp 1035-1049
Bourne AE, Creek D, Peters JMR, Ellsworth DS, Choat B, (2017) 'Species climate range influences hydraulic and stomatal traits in Eucalyptus species', Annals of Botany, vol.120, no.1, pp 123-133
Nolf M, Lopez R, Peters JMR, Flavel RJ, Koloadin LS, Young IM, Choat B, (2017) 'Visualization of xylem embolism by X-ray microtomography: a direct test against hydraulic measurements', New Phytologist, vol.214, no.2, pp 890-898
A/Professor Brendan Choat and Professor Mark Tjoelker