About

Sara C. Hotchkiss is a Professor of Botany at the University of Wisconsin–Madison. Her research focuses on studies of vegetation history, climate history, ecosystem response to climate change, disturbance and landscape dynamics, and paleoecology. Dr. Hotchkiss uses paleoecological methods to provide context for observations of modern ecosystems and to study how rare events and slow changes shape ecological history. Her current projects include investigating landscape-scale vegetation patterns in response to disturbance and climate changes on the Northwestern Wisconsin Sand Plain, monitoring the response of treeline vegetation on Maui to climate change, and studying the ecosystem effects of Sphagnum palustre in Hawaiian wet forests. She is also involved in projects examining the stability of lake ecosystems in northern Wisconsin, the development and intensification of agriculture in Hawaii over the past 1000 years, and the interactions between human societies and ecosystems. Dr. Hotchkiss is a faculty affiliate of the Nelson Institute for Environmental Studies and the Limnology and Marine Sciences Program.

Research topics

• Ecology
• Environmental science
• Physical geography
• Geography
• Geology

Selected publications

• Big Run Bog loss-on-ignition dataset

  Open MIND · 2026-02-28

  dataset

  Raw data for the Big Run Bog loss-on-ignition dataset submitted to the Neotoma Paleoecology Database. Data is available through the landing page in JSON format. The landing page referenced by the DOI also contains links to publications and a map-based viewer for the dataset. The Neotoma Paleoecology Database maintains a homepage at https://www.neotomadb.org.

  DOI

• Big Run Bog pollen dataset

  Open MIND · 2026-02-28

  datasetSenior author

  Raw data for the Big Run Bog pollen dataset submitted to the Neotoma Paleoecology Database. Data is available through the landing page in JSON format. The landing page referenced by the DOI also contains links to publications and a map-based viewer for the dataset. The Neotoma Paleoecology Database maintains a homepage at https://www.neotomadb.org.

  DOI

• Dolly Sods Bog pollen dataset

  Open MIND · 2026-02-28

  datasetSenior author

  Raw data for the Dolly Sods Bog pollen dataset submitted to the Neotoma Paleoecology Database. Data is available through the landing page in JSON format. The landing page referenced by the DOI also contains links to publications and a map-based viewer for the dataset. The Neotoma Paleoecology Database maintains a homepage at https://www.neotomadb.org.

  DOI

• Big Run Bog plant macrofossil dataset

  Open MIND · 2026-02-28

  datasetSenior author

  Raw data for the Big Run Bog plant macrofossil dataset submitted to the Neotoma Paleoecology Database. Data is available through the landing page in JSON format. The landing page referenced by the DOI also contains links to publications and a map-based viewer for the dataset. The Neotoma Paleoecology Database maintains a homepage at https://www.neotomadb.org.

  DOI

• Dolly Sods Bog charcoal dataset

  Open MIND · 2026-02-28

  datasetSenior author

  Raw data for the Dolly Sods Bog charcoal dataset submitted to the Neotoma Paleoecology Database. Data is available through the landing page in JSON format. The landing page referenced by the DOI also contains links to publications and a map-based viewer for the dataset. The Neotoma Paleoecology Database maintains a homepage at https://www.neotomadb.org.

  DOI

• Big Run Bog charcoal dataset

  Open MIND · 2026-02-28

  datasetSenior author

  Raw data for the Big Run Bog charcoal dataset submitted to the Neotoma Paleoecology Database. Data is available through the landing page in JSON format. The landing page referenced by the DOI also contains links to publications and a map-based viewer for the dataset. The Neotoma Paleoecology Database maintains a homepage at https://www.neotomadb.org.

  DOI

• Dolly Sods Bog plant macrofossil dataset

  Open MIND · 2026-02-28

  datasetSenior author

  Raw data for the Dolly Sods Bog plant macrofossil dataset submitted to the Neotoma Paleoecology Database. Data is available through the landing page in JSON format. The landing page referenced by the DOI also contains links to publications and a map-based viewer for the dataset. The Neotoma Paleoecology Database maintains a homepage at https://www.neotomadb.org.

  DOI

• Dolly Sods Bog loss-on-ignition dataset

  Open MIND · 2026-02-28

  datasetSenior author

  Raw data for the Dolly Sods Bog loss-on-ignition dataset submitted to the Neotoma Paleoecology Database. Data is available through the landing page in JSON format. The landing page referenced by the DOI also contains links to publications and a map-based viewer for the dataset. The Neotoma Paleoecology Database maintains a homepage at https://www.neotomadb.org.

  DOI

• Remembering ecologist Margaret Bryan Davis (1931–2024)

  Proceedings of the National Academy of Sciences · 2025-09-17

  articleOpen accessSenior authorCorresponding

  Margaret Bryan Davis, a prominent ecologist, died on May 22, 2024. She was a Regents Professor at the University of Minnesota and a member of the National Academy of Sciences. Her students remember her as a creative and clear-thinking scientist who combined the tools and perspectives of paleoecology with ideas and problems of ecology in order to understand long-term forest dynamics. She was a champion of diversity and equity in science.

  PublisherOA PDFDOI

• Resolution of Respect: Margaret Bryan Davis (1931–2024)

  Bulletin of the Ecological Society of America · 2025-02-17 · 2 citations

  articleOpen access1st authorCorresponding

  Margaret Bryan Davis, National Academy of Sciences member and past President of ESA, died May 22, 2024 at 92 after a long illness. She had been living in a retirement community in Boulder, Colorado, USA. Her brother, Kirk Bryan, Jr., nieces, Elizabeth Kohnstamm and Anne Hemenway, and nephew, Ben Bryan, survive her (Photo 1). Source: Bulletin of the Ecological Society of America, 74: 278. Margaret was born on October 23, 1931 in Boston, Massachusetts, USA as the youngest of four children to Mary MacArthur Bryan and Kirk Bryan, Harvard Professor of Geomorphology and Pleistocene Geology. Her interest in biology developed in high school and continued at Radcliffe where she became interested in paleobotany in a class taught by Elso Barghoorn. After graduating summa cum laude in 1953, she was awarded a Fulbright Scholarship to Copenhagen, Denmark. There she worked with Johannes Iversen, a world-renowned Quaternary palynologist, and became fascinated by the challenge of describing vegetation history since the last glacial maximum. Margaret appreciated Iversen's focus on interpreting pollen records ecologically, emphasizing the physiology and ecology of plant species (Brubaker 1987), and she returned to Harvard in 1954 to begin graduate studies in paleoecology. Both her undergraduate and graduate studies were interdisciplinary, involving geology and biology. Ecologist Hugh Raup, the director of Harvard Forest, served as her PhD advisor. Her dissertation focused on late glacial (16,000–11,000 years ago) pollen records from three sites near Harvard Forest in central Massachusetts (Davis 1958). Awarded an NSF Postdoctoral Fellowship, she pursued research at Harvard and Cal Tech between 1957 and 1960. In 1960, Edward Deevey welcomed her into his laboratory at Yale, where she did the groundwork for estimating pollen accumulation rates, among the key innovations she introduced to pollen analysis (Davis and Deevey Jr. 1964). At the University of Michigan from 1961 to 1966, she lived the life of a trailing spouse on soft money, first as a research associate in Botany and then with a joint appointment as an Associate Research Biologist at the Great Lakes Research Division. Although her research was on plants, her 1966 appointment as an Associate Professor was in the Zoology Department because of nepotism rules; her husband Rowland Davis's tenure-track appointment was in Botany. In 1970, she was promoted to full professor and began taking action to get her salary raised to an appropriate level. She and Rowland divorced that year. Her salary negotiations succeeded when encouraged by lawsuits, and in 1973, she became a professor of ecology in the Biology Department at Yale. On finding a lack of recognition and support for ecology there, she was pleased in 1976 to be appointed as professor and head of the department of Ecology and Behavioral Biology (EBB), which soon became the department of Ecology, Evolution, and Behavior (EEB) at the University of Minnesota, an appointment she held until 1981. In 1982, she was elected to the National Academy of Sciences, a first for a woman from the University of Minnesota, and she also became a Regents Professor. The 2001 ESA Meeting in Madison, Wisconsin featured a session honoring her retirement. Margaret's excellent and innovative research, along with her leadership skills and integrity, led to her being elected President of the American Quaternary Association (AMQUA; 1978–1980), a member of the National Academy of Sciences (1982), President of ESA (1987–1988), and a Fellow of the American Academy of Arts and Sciences (1991). She was selected for ESA's Eminent Ecologist Award (1993), the Nevada Medal (1993), the AMQUA Distinguished Career Award (2001), ESA's William S. Cooper Award (with coauthors) (2011), and she was in the first cohort of ESA Fellows (2012). She received an honorary doctorate from the College of Biological Sciences at the University of Minnesota in 2012 and the Alfred Russel Wallace Award from the International Biogeography Society in 2017. Margaret Davis' main research contributions follow three themes: (1) the theoretical and empirical underpinnings of pollen analysis, (2) the drivers and mechanisms of temporal change in pollen sequences, and (3) the implications of paleoecological records for ecology and global change. Margaret recognized early in her career that because of differential pollen productivity and dispersal among taxa, pollen percentages would not correspond directly to relative or absolute abundance in vegetation. Empirical and theoretical studies (Davis and Goodlett 1960, Davis 1963) set new standards for the field and led her to an internationally recognized contribution when she estimated pollen accumulation rates (PAR) from sedimentary pollen concentrations (Davis and Deevey Jr. 1964, Davis 1966, 1967). PAR had the potential to liberate pollen analysis from the constraints and potential ambiguities of percentage data, thus allowing pollen profiles to be read as direct records of plant populations. She gained new ecological insights from its initial applications, and the method was adopted widely. Margaret was not one to rest on a result without further scrutiny. She pursued studies of mechanisms of pollen deposition, revealing differences in rates of pollen sedimentation within and between lakes (Davis et al. 1971, Davis and Brubaker 1973). As was characteristic of Margaret's approach to science, she was the first to investigate the assumptions and robustness of PARs and was quick and open in critiquing and improving this widely recognized breakthrough. Davis' concern with pollen representation of vegetation continued throughout her career, with studies about how to determine species range limits from pollen networks (Davis et al. 1991) and integration of pollen productivity and dispersal studies into high-resolution reconstructions of forest patchiness (Davis et al. 1994, 1998, Davis and Sugita 1997, Davis 2000). As Margaret improved understanding of how pollen data represent surrounding vegetation, she gained critical insights into the drivers and mechanisms of vegetational change since the last glacial maximum. Margaret's detailed pollen record from Rogers Lake in Connecticut, USA, with chronological control from 54 radiocarbon dates (Davis 1969), showed the familiar sequence of tree species reaching the area and becoming abundant, with a major decline in hemlock populations 5,300 years ago and establishment of chestnuts only 2000 years ago. She then mapped the postglacial migration patterns of important tree taxa in eastern North America and provided a telling illustration of individualistic migrations with different taxa moving at different rates and in different directions (Davis 1976a, b). She argued that for many species, migration rates were unable to keep pace with climate change owing to biogeographical and ecological factors such as limited dispersal capacity, slow demographic processes, refugial locations, and geographic barriers (Davis 1976a, b, 1978, 1981, 1983a, b, 1984). In 1984, she organized a symposium on whether vegetation was in equilibrium with climate and subsequently acknowledged a major role of Holocene climate change as a driver of vegetational change. Concluding that migration lag was less important than she had previously thought (Graumlich and Davis 1993, Spear et al. 1994), she again changed her view and led the way to open up the field by using this new perspective. Margaret's recognition of the roles that biotic and demographic processes (dispersal, recruitment, pathogens, and disturbances) played in vegetation history is fundamental to ecology, conservation, and global change science. In a collaboration with Daniel Botkin, she pioneered the application of forest-succession models to hypothesis-testing in paleoecology, showing the role of rapid temperature change in driving forest dynamics (Davis and Botkin 1985). A series of lake-based studies of the roles of climate, dispersal, and geographic barriers in tree migration across Upper Michigan, USA (Davis et al. 1986, Davis 1987, Woods and Davis 1989) led to a focus on forest dynamics in the old-growth Sylvania Wilderness in the Upper Peninsula of Michigan. Those studies integrated paleoecology, forest dynamics, patch-dynamic theory, and ecosystem processes (Davis et al. 1992, Ferrari and Sugita 1996); a major finding was that biogeochemical and demographic feedbacks were sufficient to explain multigenerational persistence of a hemlock/hardwoods forest mosaic, once established, but that the physical positions of individual stands depended on species' establishment probabilities in a preexisting mosaic of hardwoods and pines (Davis et al. 1994, 1998; Photo 2). Photo credit: Randy Calcote. Margaret was interested in the conservation implications of her work over much of her career, and these assumed greater importance as recent global climate change emerged. Her convincing demonstrations that tree species migrated individualistically, and that modern plant associations have generally arisen in the last few 1000 years, continue to frame thinking about the future of terrestrial ecosystems. She was among the first to use climate-envelope modeling to examine global-change effects on species ranges, revealing potential for major lags in tree-migration responses to contemporary rates of climate change (Davis and Zabinski 1992). She also explored the question of whether evolutionary responses would be fast enough to keep pace with climatic change (Davis and Shaw 2001, Davis et al. 2005). Intellectual rigor—careful, analytical thinking, and sifting of evidence—distinguished Margaret's publications throughout her career. Margaret subjected her explanations to rigorous testing against alternatives, delineating and scrutinizing her assumptions, and examining the results from all conceivable angles. She was generally more concerned with getting things right than with getting them out. Science is not just about data and discoveries, or grants and publications. It is also about character and leadership. And those are areas where Margaret stood out. She combined a strong point of view with an openness to criticism and alternative perspectives. Over the years, she publicly acknowledged on a number of occasions that her views or conclusions on an important issue had changed. She told Randy Calcote that “it's best to show that your ideas were wrong yourself, rather than wait for someone else to do it.” She was after truths, not perceptions or pyrrhic victories. Science is a highly competitive enterprise, and Margaret was certainly competitive, like any successful scientist. But for Margaret Bryan Davis, at the end of the day, it was not about her, or about her career, or about the honors and awards she might get. It was about the science. She could put aside the “me” and look more broadly at the “we”; she was more interested in getting the science right than in advancing her fortunes. In addition to piercing brilliance and limitless creativity, Margaret epitomized integrity in science. She said that in science the right answers are not at the end of the book. It is up to you to check your work and correct your errors. When Margaret arrived at Michigan in 1961, the university had nontransparent salary policies. The system did not work well for women. During her first 5 years, her salary came from her own grants. However, after she became an Associate Professor in 1966, she found herself being paid well below the median salary for that rank. When appointed to Professor rank in 1970, her salary was well below the median salary for Associate Professors. She threatened a sex-discrimination lawsuit and asked her department chair to request a pay raise that would bring her to at least the minimum for Professors. That request ultimately resulted in a 29% pay raise, yielding a salary that was still low, given her international recognition. In 1971, she began action to gain back pay, which after a long process, the university provided as a “salary adjustment,” while avoiding the term “back pay” (Hampton 1972, Fitzgerald 2020). It was a stressful, time-consuming matter that cut into her research. Almost 40 years later Deborah Goldberg, an ecologist at Michigan, was appointed to a Distinguished University Professorship, which she named the Margaret B. Davis Chair because of Margaret being “an amazing scientist” and also “because of her refusal to tolerate unfairness” (Chapter 16 in Fitzgerald 2020). In 1990 at the University of Minnesota, Margaret chaired the Rajender salary settlement committee, tasked with managing the dispersal of a final round of funding for salary adjustments mandated by a 1980 settlement agreement of a complaint brought by Shyamala Rajender in 1973 and 1975 and certified as a class action in 1978. The committee's task was a satisfying one in light of Margaret's career-long goal of seeking gender equality in pay. In 1982, Margaret discovered massive plagiarism of a grant proposal she had previously submitted. When personal negotiations with the plagiarist broke down, she reported the matter to the offender's department chair, who independently confirmed the plagiarism. She also reported the matter to her own department head, who told her he had been plagiarized a decade before by the same individual but never reported it after confronting the offender. Margaret's decision to report the issue, though painful and stressful, made it easier for yet a third victim to speak up. She then faced another uncertain period, waiting for the slow academic procedures to grind toward confirmation of her complaint, with consequences for the plagiarist. However, she was cast as the aggressor by some colleagues for damaging the offender's career. This curious role reversal is not uncommon for whistleblowers who report unethical activity (Shaw 1982). During her 5 years as department head at Minnesota, Margaret established an atmosphere of collegiality and respect and facilitated the hiring of a leading set of ecologists. She also led a change in attitude and approach toward graduate training, including revamping the written and oral examinations. Her leadership and laboratory management served as excellent models for younger scientists. While president of ESA in 1987–1988, she promoted the development and sharing of laboratory and field experiments that would make principles of ecology real for students, and supported founding the Education Section of the society (https://www.esa.org/tiee/vol/expv1/expv1_toc.html). She also formed an ad hoc Professional Ethics Committee to upgrade the Code of Ethics for ESA. In the late 1990s, Margaret developed a strong interdisciplinary graduate training program at Minnesota entitled Paleorecords of Global Change that involved faculty from four departments on two campuses, a strong curriculum, and a fascinating seminar series. To gain funding for research, graduate students wrote proposals and sharpened their thinking with feedback. Margaret spread the resources of the training grant broadly to catalyze collaborative interdisciplinary research paired with several forms of social engagement and thus created a vibrant research community. Margaret's advising and mentoring were sincere and thoughtful. She expected each of her students and postdocs to develop their own research projects independently. She then supported their work and helped them gain advice from others, and she seldom sought coauthorship on their publications. Weekly individual meetings and laboratory gatherings made timely check-ins and guidance routine. Margaret was selective about how she invested time, energy, and resources. Her desk and most of her office was a complete mess—she was known to refer to her desk as a “stratigraphic filing system”—but the bookshelves and the primary literature she had amassed were meticulously organized. Margaret had a catalog system for the primary literature, much of it from European journals that were difficult to find in the United States. She also had a special place on the bookshelf for all the theses and dissertations she had supervised. Seeing these volumes displayed was inspirational for graduate students; it was clear that Margaret greatly valued the contributions of each student. Margaret was an easy person to be around, with a great sense of humor. She had a quick wit and a sparkle in her eye in many social situations. People from the laboratory often ate lunch together, and she made sure that birthdays and milestones were celebrated. In the field, she pitched in, working collaboratively to solve problems. She loved to eat peanut butter and pickle sandwiches for field lunch. Margaret's easy demeanor and wry humor could be set aside, however, when she sensed injustice. Colleagues around the world have stories about being recipients of her focus in fierce pursuit of justice. Many credit the experience for lasting changes in their professional ethics. As Lisa Graumlich noted, “Younger women looked to Margaret as an example of what was possible. You could challenge orthodoxy with exquisitely designed field data deeply integrated with ecological theory. You could stand up to big and powerful institutions to demand equal pay and win. You could own your ambition and build a community around you that were drawn to your vision. And you could do all of this with humor and compassion.” We thank Randy Calcote for sharing memories and sending photos, Ruth Shaw for providing documents from the Department of Ecology, Evolution, and Behavior and sending links to files about Margaret at the University of Minnesota, Lisa Graumlich, Deborah Goldberg, and Linda Brubaker for great quotes, and Jane Beiswenger for her interview with Margaret in 2015 in the Ecological Society of America Oral History Collection 2012–2022 (https://ohms.libs.uga.edu/viewer.php?cachefile=russell/RBRL416ESA-013.xml).

  PublisherOA PDFDOI

Recent grants

• DISSERTATION RESEARCH: Assessing cloud forest ecotone sensitivity to climate change in space and time

  NSF · $12k · 2008–2011

• Collaborative Research: Drought as a trigger for rapid state shifts in kettlehole ecosystems

  NSF · $201k · 2011–2017

• Collaborative Research: Disturbance, Succession, and Nutrient Availability: Patterns, Mechanisms, Interactions

  NSF · $285k · 2007–2012

• Collaborative Research: Fire and Vegetation Heterogeneity in Time and Space.

  NSF · $164k · 2003–2007

• Collaborative Research: The effect of landscape context on the sensitivity of vegetation to climate change

  NSF · $205k · 2008–2014

Frequent coauthors

• Peter M. Vitousek

  Stanford University

  33 shared

• Oliver A. Chadwick

  31 shared

• Thegn N. Ladefoged

  University of Auckland

  26 shared

• P. V. Kirch

  25 shared

• Shripad Tuljapurkar

  Stanford University

  25 shared

• Michael W. Graves

  25 shared

• Anthony S. Hartshorn

  20 shared

• Randy Calcote

  University of Minnesota

  12 shared