Resolution of Respect: Samuel J. McNaughton, 1939–2024

Abstract

Samuel Joseph McNaughton passed away peacefully at his home in Syracuse, NY on January 18, 2024. He is survived by Margaret McNaughton, his wife of 64 years, his two children, Sean (daughter-in-law Catherine) and Erin, and six grandchildren, Martine, Joshua, Shelby, Eli, Grace, and Esther.

Sam was born in Takoma Park, Md, but, in his own words, “fished, trapped, and hunted his way through much of his childhood in northwest Missouri.” After falling in love in high school, Sam and Margaret together attended Northwest Missouri State University (NWMSU), where Sam planned to study agriculture to continue the family business of farming. But while at NWMSU, he enrolled in a plant ecology course taught by Dr. Irene Mueller (a J. E. Weaver student) who helped Sam understand the patterns that had piqued his interest during his romps through nature. As part of the course, students read and critically discussed primary literature, which may have been Sam's initiation to curiosity-driven scientific investigation. This one course was ground-shifting for Sam, causing a pivot from agriculture to an interest in studying ecology, and probably instilled in him a deep appreciation for the importance of teaching, which he would carry throughout his academic career.

After graduating, Sam decided to work with Calvin McMillan at the University of Texas, Austin, which had one of the only climate-controlled plant growth facilities available at the time. He earned his Ph.D. in 1964 at the precocious age of 25, after which he spent 1 year as an Assistant Professor at Portland State University and 1 year as a postdoc at Stanford University, before starting his 38-year-long academic post at Syracuse University (SU) in 1966.

Sam's early scholarly work spanning his Ph.D. through the mid-1970s at SU focused on plant ecotypic variation, for which he used Typha as a study organism. His investigations examined the variation in production, phenotypic traits, and photosynthetic and respiratory biochemistry among populations of Typha throughout the midwestern and western United States. Because Typha overwhelmingly dominates communities, Sam's interpretations of his results spanned ecophysiological adaptation to whole community organization, a theme that would characterize his future influential studies of grassland ecosystems. His first four papers on Typha were published in 1965 and 1966 in Science (McNaughton 1965), Nature (McNaughton 1966a, b), and Ecological Monographs (McNaughton 1966c) demonstrating two features of Sam's science. First, his remarkable productivity, which Larry Wolf, a longtime friend and colleague at SU, explained by Sam's ability to very quickly produce a draft of a manuscript that would require very little further work before submission. One of us (MO) was eye-witness to this while a graduate student in the McNaughton lab when Sam came into his office one weekend, which was not his habit, and wrote, with his keyboard clattering like a storm on a tin roof, an entire NSF proposal, beginning to end with references, in just 2 days. The proposal was funded. The second feature that those papers demonstrated was Sam's interest in tackling the pressing ecological problems of the time in novel and creative ways that merited publication in the very top ecological and scientific journals. We wish to underscore that each of those four papers was single-authored by a scientist in his mid-20s.

As Sam's Typha work continued to become more biochemical, he began to lament how much his science had become laboratory oriented. Then, in 1975, Larry Wolf, who was studying sunbirds in East Africa, invited Sam and Margaret to visit him in the Serengeti (Photo 1). Years later Margaret would sardonically admit that at the time she thought it prudent to agree to the trip so that Sam would “get it out of his system.” Fortunately for the McNaughton family, who still treasure the numerous research expeditions on which they accompanied Sam, and for grassland ecology, Sam's interest in the Serengeti was not satiated by that one visit. During the trip, Larry Wolf remembers Sam's intense interest in the relationship between movements of herds of grazers and grasslands. Upon returning to SU, Sam sequestered himself in the library for a couple of weeks while he wrote his first Serengeti proposal to NSF.

Sam's work on grassland ecology focused on the Serengeti ecosystem but also impacted broader ecological issues and theories (Photo 2). His studies revealed the multifaceted interactions between plant communities and grazing herbivores, along with the moderating effects of environmental variables such as fire, rainfall, and soil. His work drew strong conclusions on the core topics of ecology, such as ecosystem structure, function, diversity, stability, energy flow, and nutrient cycling. Sam's Serengeti research integrated extensive field observations with greenhouse and growth chamber experiments at SU, which allowed him to address questions on ecosystems, plant communities, populations, species, ecotype adaptation, and plant ecophysiological mechanisms. Similar to his Typha studies, this new line of research produced a remarkable series of papers in leading journals (Nature, Science, Ecological Monographs, American Naturalist), many of which were single-authored (e.g., McNaughton 1976, 1977, 1979, 1983a, b, 1984, 1985, 1988, 1990).

In a series of observational and experimental studies, Sam showed how grazing herbivores selected for plants and sites with higher nutritional content and influenced nutrient cycling through their feeding activities. During the wet season in the Serengeti, grazers increased their diet quality by following a “green wave” of highly nutritious forage. Animals often created short and dense “grazing lawns” that maintained species composition and improved foraging efficiency by increasing the biomass and nutrients that they obtained per bite. He found that mutualistic plant–herbivore interactions would often increase plant productivity by compensatory growth, a controversial principal at first. He concluded that grazing, together with climate, fire, and soil heterogeneity, shaped the spatial heterogeneity of grasslands and savannas (Photo 3).

Sam performed a wide range of genetic and ecophysiological studies that shed light on how different plant species within a community have varied tolerances and adaptations to grazing. Prostrate growth form, fast regrowth, defensive compounds, unpalatable tissues, silica absorption, nitrogen and phosphorus uptake, and allocation all were shown by Sam's experiments to vary widely based on the coevolution between herbivores and the plants they eat. These adaptations not only influenced species survival but also the overall composition and functional diversity of plant communities. His studies on grassland ecology and plant ecophysiology allowed him to actively engage in the debate on the relationship between diversity and stability of ecosystems (McNaughton 1977).

Sam's findings offered invaluable insights into the management and conservation of grassland ecosystems, and he frequently made them explicit in diverse contexts. Recognizing the importance of rainfall, fire, and soil properties in mediating the effects of herbivory highlighted the need for management practices to consider local environmental conditions and ecosystem dynamics. Additionally, understanding the adaptive strategies of plant communities to grazing pressures informed how conservation strategies can preserve biodiversity and ecosystem function. Over his career, Sam published about 125 papers, six of which have been cited over 1,000 times. In recognition of his major contributions to understanding terrestrial ecology, Sam was awarded the ESA Eminent Ecologist Award in 2004 (Photo 4).

Throughout the many years that Sam worked in the Serengeti, his wife, Margaret, often accompanied him in the field. Margaret also took charge of the laboratory, directing the analyses of the many thousands of plant and soil samples shipped to SU and coordinating the lab work of students and postdocs. In that way, Sam's research enterprise was a team effort between husband and wife.

Despite his groundbreaking research, Sam always considered that his most important contribution would be through his teaching, perhaps as a consequence of the enormous impact that Dr. Mueller's ecology class had on him while an undergraduate at NWMSU. After arriving at SU within a few years of one another, Sam and Larry Wolf began meeting regularly to discuss their research interests. They soon realized the large knowledge gap between plant and animal ecology, with the former focusing on physiology and community dynamics and the latter on population processes. As a consequence of those discussions, they decided to offer a course that integrated the two disciplines by pairing, as much as possible, plant- and animal-oriented lectures along common themes, instead of splitting the topics up into two independent units, which was common at the time. This collaboration led to them publishing a textbook, General Ecology, in 1973 (McNaughton and Wolf 1973) that was based on their class lectures. Sam and Larry subsequently developed a field ecology course that integrated animal and plant topics in a similar fashion as their lecture course. They taught those two courses together for many years. When Sam was awarded a William R. Kenan Jr. Professorship in 1992, he could have stopped teaching, which would have been the impulse for many academics. Instead, Sam used the opportunity to develop a new Conservation Biology course, which he taught until he retired in 2004.

Roughly 25 graduate students and postdocs were advised by Sam. He was an enormously humble mentor, as eager to learn from his mentees as his mentees were from him. He was also a patient advisor, allowing his students the necessary time to labor with difficult problems. One of us (DF), while struggling to complete his dissertation, remembers Sam handing him a Bioscience commentary about how advisors should provide students sufficient time to resolve novel scientific problems. It was a message of understanding and support that was greatly appreciated. Working with his graduate students, post docs, and many other colleagues outside of his lab allowed Sam to collaborate on projects in grasslands in Africa, North and South America, and Asia, and on global patterns of herbivory.

There are standard parameters used to measure the scientific impact of a researcher such as number of publications, citations, awards, etc., and Sam certainly excelled in all of those. Another measure is the impact that a scientist has on how we think and talk about a topic. By this latter measure, Sam's impact has been enormous. At scientific meetings throughout the world, during the formal talks and the informal discourse in hallways between talks, among ecologists, agronomists, and range managers, in college courses and thesis defenses, during debates at research stations, and while “kicking the dirt” in grasslands and pastures in Pampas, Puna, Mongolia, the Great Plains, and tropical and subtropical savannas, the talk is about compensatory growth, grazing lawns, green waves, grazing ecotypes, and the many other topics championed by Sam. Now THAT is true impact!