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Davide Siclari

Candidature

PhD Candidate

Thesis title

Which plants use transpiration to survive heatwaves?

Research project

Davide ScilariUrban environments across Australia already experience 8 to 11 heatwave days per year, when extreme temperatures last for three or more consecutive days. Trees play a key role in dampening urban heat through evapotranspiration and shade, but due to climate change and the forecasted increase in heatwave severity and frequency, the survival of cities’ green areas is at risk. Immediate heatwave impacts range from alteration in plant physiological function, growth and reproduction to death. At larger spatial scales, the combination of heatwaves and drought can exacerbate other disturbances leading to a rapid decline of ecosystem resilience and changes in species composition.
Vegetation can suffer irreversible damage even after short periods of heat exposure, particularly when water availability is limited. As green infrastructure is a key element to urban heat mitigation and sensibly improves citizens health, it is crucial to better understand plant responses to extreme heat.
Therefore, the project aims are to (i) understand the effects of heat and drought stress on urban trees (ii) assess if innovative irrigation solutions could prevent heat and drought stress on trees while improving plant function and (iii) examine what’s driving increased water loss at high temperatures in urban trees. While elaborating these objectives, we also developed the intention to investigate the stomatal response to heatwaves in different species, although to determine which species show photosynthetic decoupling leading to increased water loss on hot days, our measurements must be based on the availability of temperatures over 30°C. Taking advantage of naturally occurring heatwaves, this research will evaluate changes in leaf temperature and physiological indicators of heat stress. This will be done across a range of native and exotic species in plantations and urban streets in western Sydney, Australia by using thermal imagery, infrared sensors combined with stomata conductance, transpiration, photosynthesis, minimum stomatal conductance and chlorophyll fluorescence measurements. The overall aim is to provide useful recommendations for the management of cities’ green areas and potential solutions to the urban heat mitigation issue.

Supervisors

Renee Prokopavicius, Paul Rymer, Sebastian Pfautsch, Mark Tjoelker.