Lucas A. Cernusak

Abstract

From a young age, I enjoyed spending time in and around trees and forests. I always liked being in the three-dimensional space created by forests and looking up to see what all the individual tree canopies were doing, how they were organised, and how they differed from each other. I was lucky to have parents who appreciated hiking and camping and being in the outdoors. Growing up in Idaho, USA, we often visited the conifer forests of the Pacific Northwest and the Rocky Mountains. After completing an undergraduate degree in biology, I wanted to take the general background that I had learned and focus more on forest ecosystem science, which eventually led me to tree physiology. When I started to learn about the important role that forests play in the earth system, and how they contribute to the global carbon cycle, it cemented my desire to understand more about their functioning and how their behaviour could change in response to human activities.

I love the process of formulating a question based on something I have observed in nature, or read about in a paper, and then thinking about which set of measurements would best allow the question to be answered. A lot of ecophysiological research involves finding new and creative ways to measure things and I also really enjoy this aspect. Then, after much brainstorming followed by trial and error, the data are collected and voila, the answer reveals itself. Or not, as is often the case, leading instead to many new questions, but this is also part of the fun. When at long last, the story is complete, putting it down in writing and in graphical visualisations in a way that others can understand and grasp its meaning makes for a really satisfying experience. From when I started doing research, I found this whole process so exciting that I just wanted to find ways to continue doing it.

With modern communications continually pressing to steal my attention, I try to remember to take a step back and appreciate the privilege that it is to be able to spend my time working on things that I personally find so interesting. I also draw motivation from working together with students, collaborators and co-workers, and from being part of a community that shares the same passions and enthusiasm. Knowing that someone else's progress depends on me doing my part is always a good way to stay on track. The feeling of having discovered something new or having solved one of the infinite number of riddles that the natural world presents is always pleasing, and is a fresh source of motivation. Finally, seeing a project that has been years in the making come to fruition by being neatly summarised in a scientific paper that can be sent out into the world is truly a memorable feeling. I try to remind myself of this feeling when confronted with the more mundane day-to-day tasks that often seem so far removed from these lofty end goals.

I consider myself fortunate to have had a series of mentors that I could look up to and who I truly view as role models. John Marshall at the University of Idaho, USA, provided inspiring supervision for my MSc degree and introduced me to the field of tree physiology. I remember frequent meetings in which he would interject to say, ‘I forgot, what's your hypothesis again?’ – emphasising the importance of thinking mechanistically. Graham Farquhar, my PhD supervisor, continually inspired and challenged me toward quantitative rigour and developing sound theory. Lindsay Hutley at Charles Darwin University, Australia, taught me to appreciate the joy that can come from a good day's fieldwork, whether scientific objectives were completely achieved or not. Klaus Winter at the Smithsonian Tropical Research Institute, Panama, always impressed me with his passion for precision and plant physiology in general. The reason I consider these people important role models above all is that, in addition to being excellent scientists, they are also kind, generous, fair, and always fun to work with.

A foundational paper that I really liked was by Galbraith et al. (2010), which used three dynamic global vegetation models to tease apart the relative importance of the environmental drivers (precipitation, temperature, vapour pressure deficit, and atmospheric CO₂) in driving predicted changes in biomass carbon across the Amazon basin. The results laid out a roadmap for where experimentalists could focus to better describe processes that cause the largest uncertainties in predictions of tropical forest responses to global change. Continuing on this theme, I liked the approach taken by Slot et al. (2024) to separate the temperature response of photosynthesis in leaves of tropical trees into patterns attributable to temperature with or without concomitant changes in vapour pressure deficit. Their statistical approach was employed on data generated from mature trees in the field. I also found a nice complement in the paper by Mujawamariya et al. (2021), in which they replicated tropical tree plantings at three different elevations in Rwanda to study long-term acclimation to temperature. Finally, the paper by Liang et al. (2023) was particularly insightful with respect to the scaling of water use efficiency across environmental conditions and organisational scales. I like this set of papers because it demonstrates a range of different approaches and techniques that can be applied in plant ecophysiology research broadly.

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