Evan Gora – Harper Prize Shortlist

Throughout May, we are featuring all the articles that were shortlisted for the Harper Prize 2020. The Harper Prize is an annual award for the best early career research paper published in Journal of Ecology.

Evan’s article ‘A mechanistic and empirically supported lightning risk model for forest trees was one of the eight papers shortlisted for this year’s award.

Ecologist Evan Gora with his loyal field companion, Rooney. Photo credit: Jane Lucas

Tropical forests are beautiful ecosystems. When we think of them, we usually think of the sun sifting through the canopy and an incredible array of sights and sounds from a diversity of life. However, if you’ve spent enough time in tropical forests, you know the feeling when it suddenly gets very, very dark in the middle of the day and life gets very still. Your eyes adjust to the dim light and you hear the rush of wind through the forest canopy. This signals the arrival of a sudden thunderstorm. Humans and animals can hide and take shelter, but trees must stand in place, exposed to the wind and lightning.

Much of my research aims to understand how trees are killed by lightning during these storms. Our recent work in Journal of Ecology takes the first major step in understanding why lightning only strikes certain trees in a forest. My co-authors and I constructed a mechanistic model of lightning strike risk based on tree structure and location, and we validated this model using unique field data from a one-of-a-kind lightning location system. Our results show that lightning non-randomly strikes the largest, and typically oldest, trees in a forest because of their greater height and crown area. This mechanistic model explains how lightning strikes shape forest structure and biomass turnover, with major implications for global carbon cycling.

These results are timely because our related work has demonstrated that lightning is a major, yet cryptic, driver of large tree mortality in tropical forests (Yanoviak, Gora, et al. 2020. New Phytologist). Because of their disproportionate effects on large trees, higher lightning frequency is associated with fewer large trees per ha, higher rates of biomass turnover, and less total aboveground carbon storage pantropically (Gora et al. 2020. Global Change Biology). Our study provides a mechanistic explanation for how the physical process of a lightning strike biases its effects towards the largest trees and causes these recently discovered associations with key forest characteristics. Quantifying this biophysical process is critical to understanding how changing climatic conditions – which are expected to alter lightning disturbance regimes – will reshape tropical forest structure and carbon cycling.

This cartoon depicts the basic components of our mechanistic model of lightning strike damage. We modelled the likelihood that trees are directly struck by lightning as a function of their canopy status (emergent, canopy, or subcanopy in panel b) and exposed crown area (Af values in panel a). We then modelled the probability that each nearby tree is secondarily damaged by lightning as a function of their diameter and either the distance between their crowns (dc) or the distance between their trunks (dt). The results enabled us to estimate the frequency with which all trees in this forest are struck by lightning, thereby demonstrating that the probability of being struck by lightning increases with tree size and varies among tree species. All of these models were validated using field data from lightning strikes located with a unique remote location system.

My interests in nature began early in life, and then harmonized with science at university. I grew up on a semi-operational farm in Appalachian Pennsylvania, surrounded by a matrix of forests and subsistence farms. I developed a deep connection with nature during this time and I have always been interested in science, but I didn’t understand how those interests could intersect outside of medicine until I attended the University of Pittsburgh. I was largely disillusioned with biology and focusing my energy on economics when I decided, on a whim, to take an Ecology class with Walter Carson. Walt was the first actively researching ecologist I had ever met, and I was immediately inspired. I contacted Walt about opportunities to conduct research and he connected me with his graduate student, Eric Griffin, who I worked for that summer. I was broke, the work was hard, and I loved every second of it. After that experience, I knew this was the career for me.

This first opportunity led to others and the beginning of my career as an ecologist. However, as I was nearing graduation, I didn’t feel ready for graduate school, so I began searching for a technician position to broaden my research experience. Walt encouraged me to contact Steve Yanoviak who was beginning a project investigating the ecological effects of lightning. I ended up joining Steve’s lab at the University of Louisville as a technician in 2013 and then started my PhD with him in the fall of 2014.

Like most people, I grew tremendously as a person and a scientist during my PhD. After living nearly my entire life in Pennsylvania, I spent most of the next four years living on Barro Colorado Island at the Smithsonian Tropical Research Institute (STRI) in Panama. I managed the implementation and field deployment of a unique lightning location system while simultaneously conducting my PhD research on dead wood cycling and decomposition. I was fortunate to work with and learn from a diverse group of collaborators on multiple unrelated projects, ranging from the UK (soil and plant ecologists Emma Sayer and Ed Tanner) to Panama (quantitative ecologist Helene Muller-Landau, who has advised me during multiple STRI fellowships) and the US (atmospheric physicists Phillip Bitzer and Jeff Birchfield; forest ecologist Stefan Schnitzer; microbial ecologist Jane Lucas). I finished my PhD in 2018 and transitioned into a postdoctoral position with Steve Yanoviak to continue our collaborative work on the ecological effects of lightning. After five years of field campaigns, we had located enough lightning strikes to begin understanding how lightning shapes tropical forests, leading to this publication in Journal of Ecology.

Two large individuals of Prioria copaifera that were struck by lightning two months prior to this photo and died rapidly from their injuries. These trees towered over their neighbours and had expansive crowns, increasing the likelihood that they would be struck by lightning. Photo credit: Evan Gora.

Overall, I am incredibly fortunate that my profession aligns with my passions. It is a cliché, but I rarely feel like I am going to “work” because I love what I do. Forests have always been a natural form of therapy for me, and studying forest ecosystems is a dream come true. I am continuing to pursue this dream job and share this passion with students and interns as an Earl S. Tupper Fellow at STRI and a Research Fellow at the Cary Institute of Ecosystem Studies.

We announced the winners for the Harper Prize 2020 at the end of April, find out more on the blog.

You can also read all 8 shortlisted papers in our new Harper Prize 2020 Virtual Issue. These articles are free to read for a limited time!

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