ABSTRACT
Climate warming threatens the future performance of vegetation by pushing plants above their optimal temperatures for photosynthesis and growth. In extreme cases, heat wave events may also cause irreversible damage to plant tissues by exceeding physiological tolerance thresholds. Plants may exhibit resiliency in the face of warming and extreme climate events through plastic acclimation of physiological processes, including photosynthesis, respiration, and thermal tolerance. Greater acclimation capacity is often assumed to translate into greater resiliency in the face of warming or extreme weather events, thus to better forecast the effects of climate change on vegetation, it is key to understand the drivers of variation in physiological acclimation capacity. Here, I report on preliminary results from two controlled environment studies examining the effects of long-term warming and acute heat stress on physiological acclimation in more than 20 species of Eucalyptus and Corymbia. I examine possible relationships between biogeography, climate of origin, leaf traits, and physiological acclimation responses in photosynthetic capacity, leaf-level dark respiration, and photosystem II thermal tolerance. Using Eucalypts representing widely contrasting range sizes and home climates across Australia, I explore whether greater geographic distribution size or climate of origin are associated with the ability of these plants to acclimate their photosynthetic and respiratory apparatus or heat tolerance thresholds.

BIOGRAPHY

Josef Garen is a Postdoctoral Research Fellow at Hawkesbury Institute for the Environment, Western Sydney University. He is an ecophysiologist with broad interests in the effects of climate change on plant function. His work has generally focused on photosynthetic acclimation, leaf-level water use under drought, and development of gas exchange methodology. Josef completed his PhD with Sean Michaletz at the University of British Columbia in Vancouver, Canada in 2024.