Forest Futures

Forest Futures


Know the risks of investing in forests.

Given the tremendous ability of forests to absorb carbon dioxide from the atmosphere, some governments are counting on planted forests as offsets for greenhouse gas emissions—a sort of climate investment. But as with any investment, it’s important to understand the risks. If a forest goes bust, researchers say, much of that stored carbon could go up in smoke.

In a paper published in Science, University of Utah biologist William Anderegg and his colleagues say that forests can be best deployed in the fight against climate change with a proper understanding of the risks to that forest that climate change itself imposes. “As long as this is done wisely and based on the best available science, that’s fantastic,” Anderegg says. “But there hasn’t been adequate attention to the risks of climate change to forests right now.”

Meeting of Minds

William Anderegg

In 2019, Anderegg, a recipient of the Packard Fellowship for Science and Engineering from the David and Lucile Packard Foundation, convened a workshop in Salt Lake City to gather some of the foremost experts on climate change risks to forests. The diverse group represented various disciplines: law, economics, science and public policy, among others. “This was designed to bring some of the people who had thought about this the most together and to start talking and come up with a roadmap,” Anderegg says.

This paper, part of that roadmap, calls attention to the risks forests face from myriad consequences of rising global temperatures, including fire, drought, insect damage and human disturbance—a call to action, Anderegg says, to bridge the divide between the data and models produced by scientists and the actions taken by policymakers.

Accumulating Risk

Forests absorb a significant amount of the carbon dioxide that’s emitted into the atmosphere—just under a third, Anderegg says. “And this sponge for CO2 is incredibly valuable to us.”

Because of this, governments in many countries are looking to “forest-based natural climate solutions” that include preventing deforestation, managing natural forests and reforesting. Forests could be some of the more cost-effective climate mitigation strategies, with co-benefits for biodiversity, conservation and local communities.

But built into this strategy is the idea that forests are able to store carbon relatively “permanently”, or on the time scales of 50 to 100 years—or longer. Such permanence is not always a given. “There’s a very real chance that many of those forest projects could go up in flames or to bugs or drought stress or hurricanes in the coming decades,” Anderegg says.

Forests have long been vulnerable to all of those factors, and have been able to recover from them when they are episodic or come one at a time. But the risks connected with climate change, including drought and fire, increase over time. Multiple threats at once, or insufficient time for forests to recover from those threats, can kill the trees, release the carbon, and undermine the entire premise of forest-based natural climate solutions.

“Without good science to tell us what those risks are,” Anderegg says, “we’re flying blind and not making the best policy decisions.”

Mitigating Risk

In the paper, Anderegg and his colleagues encourage scientists to focus increased attention on assessing forest climate risks and share the best of their data and predictive models with policymakers so that climate strategies including forests can have the best long-term impact. For example, he says, the climate risk computer models scientists use are detailed and cutting-edge, but aren’t widely used outside the scientific community. So, policy decisions can rely on science that may be decades old.

“There are at least two key things you can do with this information,” Anderegg says. The first is to optimize investment in forests and minimize risks. “Science can guide and inform where we ought to be investing to achieve different climate aims and avoid risks.”

The second, he says, is to mitigate risks through forest management. “If we’re worried about fire as a major risk in a certain area, we can start to think about what are the management tools that make a forest more resilient to that disturbance.” More research, he says, is needed in this field, and he and his colleagues plan to work toward answering those questions.

“We view this paper as an urgent call to both policymakers and the scientific community,” Anderegg says, “to study this more, and improve in sharing tools and information across different groups.” Read the full paper @ sciencemag.org

 

 

by Paul Gabrielsen first published in @theU

 

Biological Invaders

Science Research Initiative


Fox Squirrel Biology Research STREAM

Denise Dearing, PhD, Distinguished Professor, School of Biological Sciences
Tess Stapleton, PhD Candidate, School of Biological Sciences

 

Dr. Denise Dearing

Biological invaders are one of the key drivers of ecosystem change. Invasion can result in loss of native species, reduction of ecosystem diversity, and even loss of ecosystem services such as soil stabilization, water filtration, and natural pest control. These disturbances can cause long-term disruptions and even extinction of native species. Therefore, it’s imperative to understand the effect of invaders if we wish to preserve local ecosystems.

Fox Squirrel (Sciurus niger)

For the last hundred years, the fox squirrel (Sciurus niger) has used human urbanization to spread out of its native eastern range and to invade the western United States. In 2011, these invasive squirrels were first spotted in Utah along the Jordan River Parkway and have since spread into the Salt Lake Valley.

This area is home to two native Utah species, the rock squirrel (Otospermophilus variegatus) and the red squirrel (Tamiasciurus hudsonicus). How far these fox squirrels have spread throughout the valley, whether they are moving into the mountains, and how they affect these native species remains unclear.

The goal of this project is to determine the current range of this invasive squirrel, including how much they overlap with native species and how far east and upslope they extend. Working in collaboration with the natural history museum we will document sightings, collect voucher specimens, and prepare study skins of fox squirrels.

This project will greatly contribute to ongoing work on the spread of these invasive animals and these specimens may be used for decades to come.

 

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Karl Gordon Lark

photo by Ben Okun

Karl Gordon Lark, Distinguished Professor Emeritus at the University of Utah, passed away on April 10, 2020, after a seven-year battle with cancer. A renowned geneticist, Lark uncovered fundamental aspects of DNA replication and genetics across many systems, from bacteria to soybeans to dogs. He came to the U in 1970 as the biology department’s inaugural chair with a vision—to build a research and teaching powerhouse in the desert. In just six years he recruited 17 faculty members from all biological disciplines, establishing an institution of scientific excellence.

“Today, the tremendous impact of Gordon’s vision and leadership are felt in the School of Biological Sciences, across campus and throughout the state of Utah,” said Denise Dearing, director of the school. “Gordon was responsible for the expansion of molecular biology—a new field in those days—across the U. He will be dearly missed.”

“The [University of Utah’s] nascent research community, in every field from molecular biology to community ecology, was built by Lark in creative, often wildly unconventional small steps,” wrote Baldomero “Toto” Olivera, Distinguished Professor of Biological Sciences, in an unpublished essay for the Annual Reviews of Pharmacology and Toxicology.Olivera conducts world-renowned research on cone snail venom and pain management, and was recruited by Lark. “It is his guidance that makes me feel unconstrained in exploring unusual solutions to seemingly intractable problems.”

Lark was preceded in death by his first wife, Cynthia (née Thompson). He is survived by his four children, Clovis, Ellen, Suzanna and Caroline and his granddaughter, Willow. He is also survived by his second wife, Antje Curry, his stepdaughter, Tara, and her two children, Liam and Briar. 

A life of inquiry

Curiosity and coincidence guided Lark’s lifelong pursuit of discovery. He was born on Dec. 13, 1930, in West Lafayette, Indiana, into a household that valued intellect. His father was physics chair at Purdue University and his mother was an artist and psychiatrist. Lark was precocious in his academic pursuits and enrolled at the University of Chicago a year after World War II ended at the age of 15. There, he met Leo Szilard, regarded as the father of the Manhattan Project but who had turned his attention from nuclear reactions to the newly emerging field of the molecular basis of life. Szilard suggested that Lark spend the summer at Cold Spring Harbor, a famous laboratory that helped develop the field of molecular biology. There, Lark met Mark Adams, a scientist from New York University who would become Lark’s mentor.

Adams studied phages, which are viruses that invade bacterial cells and take over various host functions to propagate themselves. He not only inspired Lark’s love of research, but also taught him how to organize effective undergraduate science education. In the fall, Lark returned to Chicago to complete his degree and had his first eureka moment—he discovered reversible changes in the physical structure of phage proteins. It would be about four more years before the field generally accepted that molecules could change a protein’s shape.

“To this day, I think it’s one of the best pieces of science I’ve ever done,” Lark reflected in comments to the U’s American West Center. “It was the bringing together of physics and chemistry and biology into one moment. I didn’t think of it that way at the time, but from then on I was hooked!”

Lark returned to Cold Spring Harbor in the summer of 1950 to work with Adams, and there he met his future wife and scientific collaborator, Cynthia. Lark completed his doctorate at NYU, spent two years as a postdoc at the Statens Serum Institut in Copenhagen, Denmark, and one year at the University of Geneva. On subsequent return visits, he met Costa Georgopoulos, a biochemist who discovered a new class of proteins called chaperones. More than 20 years after they first met, Georgopoulos would move to the Department of Biochemistry at the U.

“Gordon and I shared many old friends and colorful memories from our times in Switzerland,” Georgopoulos remembered. “Gordon’s nickname in the lab was ‘double-decker’ because his plentiful, high-rising hair resembled a double-decker bus.”

In 1956, Lark accepted a position at St. Louis University Medical School. Here, Lark had what he called his second epiphany—an experiment to show that in the absence of protein synthesis, replication of DNA stopped at a particular point on the bacterial chromosome. The experiment set the course of his research for the next two decades. In 1963, the Larks moved on to the physics department at Kansas State University where they focused their research on the process of DNA replication in bacteria. They pioneered how to measure the point when DNA begins replicating, how to track the progression of replication in living cells and developed the technique of measuring the size of cells before they begin to replicate. In 1965, the American Association for Microbiology honored Lark with the Ely Lilly Award, given each year to recognize landmark research in microbial physiology.

Building scientific and teaching excellence in Utah

In 1970, the U’s Robert Vickery recruited Lark to build a powerful new biology department in what would become the School of Biological Sciences in 2014. And build he did. During his time as chair from 1970-77, he hired 17 new tenure-track faculty, including Mario Capecchi who would subsequently become a Nobel Prize laureate, Raymond Gesteland and Ray White, who went on to establish new departments in the School of Medicine.

“As chair, Gordon was an unusually skilled administrator, combining a rare insight into the environment that different members of faculty and staff needed to succeed and the energy to provide it,” said Capecchi. “I was attracted to the young Utah biology department in part by Gordon’s support of long-term studies aimed at significant problems, but without the promise of immediately publishable results, quite different from the ‘publish-or-perish’ policies imposed at many other places.”

Lark also impressed the importance of teaching to the biology faculty, both by personal example and with innovative programs. In the department’s very early days, he hired one of the world’s most charismatic young science personalities, David Suzuki, as a visiting scholar to teach the introductory course in genetics. He implemented video recordings of well-taught introductory courses so they could be offered more frequently to more students. For several years as chair, he funded an annual program in which a prominent faculty member from outside the College of Science taught a course in their own area, designed for biology students.

“During Gordon’s final years after retirement and while battling cancer, he voluntarily and unpaid taught an Honors course for a general student audience. With biographical and autobiographical readings, he introduced the human sides of pioneers in the exciting advances of 20th century physics and chemistry, several of whom Gordon had known personally,” said Larry Okun, professor emeritus of biology. “He taught that course right through 2019, his own last fall semester.”

In Utah, the Larks turned their attention from bacteria to plant cells and tissues, particularly soybeans, for the next decade. In the early 1990s, disaster and serendipity struck—the Lark lab was destroyed while the building was under renovation. After a year of trying to salvage their work, they switched to studying whole soybean plants in agricultural fields, focusing on the genetics underlying certain traits, such as the ability of the crop to adapt to different climates. Overall, their laboratory identified genes that increased the yield of soybeans by 10%.

In 1996, tragedy and serendipity struck again. The Lark’s Portuguese water dog, Georgie, had died of an autoimmune anemia disease. Heartbroken, the Larks connected to a dog breeder, Karen Miller, to buy another puppy. When the time came, Miller gave Lark the $1,500 dog for free hoping to guilt him into studying the breed’s genetics.

It worked. Miller coordinated with Portuguese water dog owners from around the country to send Lark blood samples and X-rays of their pets. What became known as “The Georgie Project,” eventually identified genes that determine the size and shape of the head, thickness of the thigh bone, shape of the pelvis and characteristics of the lower foreleg.

A legacy that spans generations

Lark formally retired from the U as a Distinguished Professor in 1999, but his legacy in biology reaches beyond his direct collaborators. The next generation of biologists also feels his influence.

“The magnitude of Gordon’s accomplishments is hard to really capture in today’s world,” said David Grunwald, professor of human genetics at the U’s School of Medicine. “Individuals can have a big effect on an institution. They can either set a precedent that honors creativity, respect and excellence, or they can make everyone feel like a cog in a machine. Gordon built a place that engendered creativity.”

The K. Gordon Lark Fund was established in 2018 by the School of Biological Sciences in anticipation of growing it to a fully endowed-chair in his name. To honor his memory, donors can make gifts to the endowment here.

 

 - by Lisa Potter

Courtship Condos

Dean Castillo

Playing to the ethic of pursuing pure science, new faculty member Dean Castillo is driven by research questions not necessarily the research organism. While working on his bachelor’s and even before that while growing up in rural northern California, he worked with “tons of different organisms,” he says, including fungi. So it wasn’t difficult for him as a geneticist to move from his earlier subjects such as tomatoes and nematodes at Indiana University, where he earned his PhD, to fruit flies (Drosophilia) during his postdoc at Cornell and now at the University of Utah.

The question for Castillo was the same: how do natural and sexual selection shape mating interactions and behaviors, species interactions, and ultimately speciation?

The focus of Castillo, a recent faculty arrival at the School of Biological Sciences, remains evolutionary interactions between organisms, whether in “fruit” or the flies that feed on the yeast of that fruit. Genes determine behavior, and in the case of the fruit fly the female can mate with more than one male and store different sperm in different organ “storage areas” before determining which sperm will be used. How does that anatomically happen and what genes are motivating the female to determine which sperm is used?

Drosophilia - Fruit Flies

“Why does one female mate but another doesn’t?” he further asks. Once his lab determines how and where sperm from two different males is being stored in one female they will pursue other areas of inquiry: finding the genes that control female choice in the brain and, instead of pollen competition from his tomato days, it’s now sperm competition.

The equipment Castillo uses for his research includes one centimeter-high glass “condos” for the tiny flies with removable “gates.” From cotton-topped vials where the flies live on a bed of molasses and yeast, the researcher inserts a female in one side of a bifurcated chamber and a male in the other. Once the researcher lifts the gate between the sides, they can observe the eternal mating behavior of the two sexes on the micro level.

Behavior is only part of the Castillo lab’s integrative approach which combines these condo experiments with population and molecular genetics to understand the genetic basis of sexual behaviors. The approach is also designed to explore the reduction or cessation of reproduction between members of different species. (Think of crossing a horse and a donkey to produce a mule, which is sterile). Comparative genomics can help track this “reproductive isolation,” as it is termed, across the tree of life.

Drosophilia - Fruit Flies

“By studying the mechanistic and genetic links between sexual selection and reproductive isolation we can determine the influence of these forces on generating biodiversity,” says Castillo, sitting in the adjacent office to his lab on the fourth floor of the Aline W. Skaggs biology building. The almost feral view out his windows eastward to the Wasatch is a reminder of one of the big attractions to taking a position at the University of Utah: its stunning setting and, perhaps more importantly, its accessibility to wild nature. In fact, the flies that Castillo studies are easily found in the area, including in American Fork Canyon and Zions National Park. His wife Deidra, who with Dean also earned her PhD from Indiana University at Bloomington, begins her research soon in the Vickers lab one floor down. It turns out that there is overlap between her research in plant-insect interactions and Vickers’ research in moth olfaction and neuroethology.

Managing courtship condos to get at basic biology questions like how genes control behavior can seem random, even mercurial. This is especially true when compared to the careful planning required to procure one’s own family when both parents are academics. (The Castillos have three children, including a one-year-old.) It turns out that their first child was born during qualifying exams. Later, number two entered the scene while they were both defending their theses, the third during their postdocs prior to their move to Utah.

 

Dean Castillo with a few thousand research subjects.

For the time being, the five Castillos will be staying put except, perhaps, for combining science with mountain and high-desert camping trips looking for fruit flies.

by David Pace

 

Running with Scissors

Jamie Gagnon

One could argue that the age of genomes is divided between before CRISPR-Cas9 and after CRISPR-Cas9 (commonly referred to as just “CRISPR”). As a Harvard post-doc studying the genes involved in embryo development, James (Jamie) Gagnon remembers in 2012 that “pivotal moment” when these “really nice pair of scissors now easy to make” came on the scene.

“Before CRISPR,” says Gagnon whose interest early on had been more in engineering than biology, “we were all using the earlier generation of genome editing tools. Even so, we were able to determine that after making a mutation in a cell, when it divided, the change that had been made was inherited.”

The new “scissors” rapidly scaled up genome editing, allowing researchers to more easily alter DNA sequences and modify gene function. At the time CRISPR was inspiring others to move from the research model of smaller organisms like the c. elegans, a transparent worm made up of approximately 1,000 cells, to much larger ones like zebrafish. “The power of genetics,” Gagnon says, “is that zebrafish are now genetically accessible model of all vertebrates, including humans which share 70 percent of genes with fish.”

Zebrafish Research subjects

The impulse for Gagnon’s current work in vertebrate lineage and cell fate choice happened in Northern Maine, during a winter-mountaineering trip with his friend and fellow researcher Aaron McKenna whom he met while they were undergraduates at Worcester Polytechnic Institute in Massachusetts. There in the wilds, not far from Vermont where Gagnon grew up, ensued an extended conversation between the two which started to form a deeply complex but exciting research question.

“If we want to study how embryos grow, we have to do it in a living animal,” Gagnon remembers acknowledging to McKenna. “We knew we needed to do it [research] in live animals, complete and whole. I couldn’t shut up about it for several days,” he says, smiling. “Everyone was mutating genes.” It seems that at the time, and perhaps still to this day, ‘Let’s break a gene and see if you’re right about what it does’, was pro forma.

Zebrafish Scale

Instead, the developmental biologist (Gagnon) and the computational researcher (McKenna) decided to pick up where others had ended (and published), using technology in a creative way to mark cells with a genetic barcode that could later be used to trace the lineage of cells. The two were suddenly using data sets of CRISPR-scissor mutations to figure out how cells actually developed in zebrafish.

Still, the prevailing question for Gagnon the researcher is how does biology build an animal with millions of cells, all sharing information and all shape-shifting at the same time? And how does science then best go about studying that?

How does science turn chaos and cacophony into a symphony that is the marvel of a living organism?

A symphony orchestra isn’t a bad metaphor for the edge of science that Gagnon and his lab and colleagues find themselves standing at. (It helps, perhaps, that his wife Nikki, a trained studio artist, works at the Utah Symphony | Utah Opera.) “For thirty years,” says Gagnon, people have been deciphering the genome code … one of the worst computer codes ever written.” Just how bad is bad? Imagine three billion letters in one long line with no punctuation or formatting.

The Gagnon Lab

Perhaps it’s the engineer in him, but to get at that unwieldy code, he sees his task as finding additional tools to regulate CRISPR activity. These tools include doing base-editing and using self-targeting guide RNAs to facilitate cells themselves making a record of what they’re doing, what they’re listening to, as it were, as they play their own “score” of development. “We want to turn the single, really good sharp knife of CRISPR,” he explains “into a Swiss Army knife” to figure out the score of an organism’s symphonic work.

The micro-scissors of CRISPR that appear to have issued a sea change in genomic studies, he hopes, can be used to “force cells to make notes along the way” of their own developmental journey. “Every time the oboe plays,” he says, returning to the metaphor, “we want the player [the cell] to make a record and journal entry on it.”

Illustration by The Gagnon Lab

“In early embryos, there are multiple languages or instruments being used by a finite number of cells to communicate with other cells and to build an animal,” he continues. To which language/instrument does a cell “listen” to, and what choices (expression) does it make as a result?

In a sense Jamie Gagnon is no longer just trying to “decode” the genome, but to use CRISPR to make a version, readable to humans, of what cells are doing in real time and how. In short he’s looking for the creation of a cell-generated Ninth Symphony, a complex but coordinated record of how development occurred that a Beethoven would be proud to conduct.

It may be dangerous to run with scissors, something parents routinely warn their children of, but it turns out that a really good pair of them can do more than the obvious: they can inspire other technologies that promise to bend the arc of science towards even greater aspirations.

 

by David Pace

- First Published in OurDNA Magazine, Fall 2019

TreeTop Barbie

When Nalini Nadkarni was a young scientist in the 1980s, she wanted to study the canopy – the part of the trees just above the forest floor to the very top branches.

But back then, people hadn't figured out a good way to easily reach the canopy so it was difficult to conduct research in the tree tops. And Nadkarni's graduate school advisors didn't really think studying the canopy was worthwhile. "That's just Tarzan and Jane stuff. You know that's just glamour stuff," Nadkarni remembers advisors telling her. "There's no science up there that you need to do."

They couldn't have been more wrong. Over the course of her career, Nadkarni's work has illuminated the unique and complex world of the forest canopy.

She helped shape our understanding of canopy soils — a type of soil that forms on the tree trunks and branches. The soil is made up of dead canopy plants and animals that decompose in place. The rich soil supports canopy-dwelling plants, insects and microorganisms that live their entire life cycles in the treetops. If the canopy soil falls to the forest floor, the soil joins the nutrient cycles of the whole forest.

She also discovered that some trees are able to grow above-ground roots from their branches and trunks. Much like below ground roots, the aerial roots can transport water and nutrients into the tree.

During Nadkarni's early work as an ecologist she began to realize something else: There weren't many women conducting canopy research.

Nadkarni was determined to change this. In the early 2000s, she and her lab colleagues came up with the idea of TreeTop Barbie, a canopy researcher version of the popular Barbie doll that could be marketed to young girls.

She pitched the idea to Mattel, the company that makes Barbie. "When I proposed this idea they said, 'We're not interested. That has no meaning to us," says Nadkarni. "We make our own Barbies."

Nadkarni decided to make them herself anyway. She thrifted old Barbies; commissioned a tailor to make the clothes for TreeTop Barbie; and she created a TreeTop Barbie field guide to canopy plants. Nadkarni sold the dolls at cost and brought TreeTop Barbie to conferences and lectures.

Her efforts landed her in the pages of The New York Times, and word eventually got back to Mattel. The owners of Barbie wanted her to shut down TreeTop Barbie due to brand infringement.

Nadkarni pushed back.

"Well you know, I know a number of journalists who would be really interested in knowing that Mattel is trying to shut down a small, brown woman who's trying to inspire young girls to go into science," she recalls telling Mattel.

Mattel relented. The company allowed her to continue her small-scale operation. By Nadkarni's count, she sold about 400 dolls over the years.

Then in 2018, more than a decade after Nadkarni started TreeTop Barbie, she got an unbelievable phone call. National Geographic had partnered with Mattel to make a series of Barbies focused on exploration and science. And they wanted Nadkarni to be an advisor.

"I thought, this is incredible. This is like full circle coming around. This is a dream come true," says Nadkarni.

For its part, Mattel is "thrilled to partner with National Geographic and Nalini," a spokesperson told NPR.

Nadkarni knows that everyone might not approve of her working with Barbie. Barbie's role in creating an unrealistic standard of beauty for young women has been debated. Nadkarni has also wrestled with how she feels about it.

"My sense is yes she's a plastic doll. Yes she's configured in all the ways that we should not be thinking of how women should be shaped," says Nadkarni. "But the fact that now there are these explorer Barbies that are being role models for little girls so that they can literally see themselves as a nature photographer, or an astrophysicist, or an entomologist or you know a tree climber... It's never perfect. But I think it's a step forward."

Nadkarni is an Emeritus Professor at The Evergreen State College, and currently is a professor in the School of Biological Sciences at the University of Utah.

 

Nalini Nadkarni's story has appeared in The Washington Post, Time Magazine, Taiwan News, News India Times, Philadelphia Inquirer, National Geographic, The Guardian, Science Friday, San Francisco Chronicle, India Today, India Times, KSL News, Salt Lake Tribune, USA Today, BBC, The Morning Journal, CNN, UNEWS, Star Tribune, National Science Foundation, Continuum, TreeHugger, and many others.

 

 

- First Published by NPR News, Fall 2019

 

Going with the Flow

Retiring botanist studied how plant's xylem tissue carries phenomenal amounts of water to tree leaves where it evaporates and influences regional weather patterns.

John Sperry grew up in Normal, Illinois, but his interest in plants–eventually their vascular function–would propel him into work that was far from standard in botany via Duke University and, eventually Harvard where he earned his PhD. At Harvard his Swiss-born mentor Martin Zimmermann was considered among the top plant physiologists in the world and a scholar whom Sperry credits with, more than anyone else, “showing him how” to do research. Even so Zimmermann strongly questioned the ability of Sperry’s proposed, novel technique to measure the blockage of vascular flow by cavitation.

It was the ultimate success of that technique and new discoveries of how vascular tissues, or xylem in particular, function in conducting water and dissolved nutrients upward from roots, that would become the subject of Sperry’s PhD thesis. And it was that thesis and the questions it  spawned that laid the foundation of all of the research he would do for the next 30+ years, including a stint as a post-doc at the University of Vermont prior to his arrival at the University of Utah in 1989.

“As humans, we are acutely aware of the importance of maintaining vascular function,” Sperry’s Research Statement reads. “To plants it is no less critical. My laboratory investigates hydro-vascular structure and function in plants in relation to their ecology, physiology, and evolution.” The scale of this function in plants is, he explains, a “phenomenal process. The sheer quantity of water moved through plants often exceeds river flow on a watershed scale,” he explains. “The plant's xylem tissue carries all of this water to the leaves where it evaporates and influences regional weather patterns.”

It takes “watershed scale” flow for plants to obtain CO2 from the atmosphere through their open stomata. It’s counter-intuitive, but the transport is driven by negative liquid water pressure, “a remarkable fact,” says Sperry “that will always irritate physicists” who often aren't as familiar with  metastable fluids as  is a plant physiologist.

Sperry and his lab study how plant form and function have evolved. To do this they have developed more efficient technologies for the larger data sets required. Sperry custom designed centrifuge rotors to  quickly expose the vascular system of plants to a known negative pressure. This in turn has allowed him to create the kinds of vulnerability curves which improve prediction of plant water use and to help move his research toward macro applications in forests to predict plant responses to climate change.

What does the coordination look like between regulation of photosynthesis and environmental conditions? The answer lies in predicting what the stomata will do.  Stomata are typically found in the epidermis of plant leaves. Specialized “guard cells” surround stomata and function to open and close stomatal pores,  balancing the trade-off of water evaporation for required carbon dioxide.

“We … concentrate on the fundamental carbon-for-water trade-off that confronts all terrestrial plants,” continues Sperry. “Photosynthesis requires the plant surface to be porous to CO2 diffusion, but at the cost of also being porous to evaporative water loss.” Indeed, the xylem has been called "the vulnerable pipeline,” part of an elaborate system that includes “a transport system that teeters on the edge of physical possibility.” Failed water transport, or “cavitation,” is caused by water stress or freezing. Over the years, Sperry has learned that some plants are more vulnerable to this kind of “spectacular failure” than others. “This turns out to be part of the answer to the question of why some plants grow where they do when others cannot,” says Sperry. Vulnerability to cavitation provides the key to predicting how stomata respond to environmental cues, a missing element that Sperry and colleagues have integrated into predictive models for how plants respond to their environment.

It’s not surprising then that Sperry’s work in plant hydraulics–the water stresses and trade-offs they face–has had a profound impact on predicting how rapid environmental change will affect the future of plants and forests. This according to U ecologist and Sperry colleague William “Bill” Anderegg. Before his own appointment in Biology, Anderegg, who was studying Colorado forests, spent time in Sperry’s lab. There he learned first-hand what was confirmed later for him about Sperry’s mentoring of young researchers.

“I attended a major conference in the field recently,” says Anderegg, “where there was a ‘mentor tree’–an artistic set of wooden branches where young scientists anonymously wrote the name of someone who had changed their career…. John's name was all over the tree and was the most frequent name by far.”

Sperry will retire from the University of Utah in December, so it’s a time to look back on a career that started, in retrospect, as early as kindergarten in his hometown of Normal. “Of course I was also obsessed with being a truck driver,” he adds. “But I did draw lots of trees and enjoyed watching our teacher demonstrate the ascent of food coloring in the transpiration stream of a celery stalk.”

But like a true scientist he is always looking forward as well, not just finding a home for that centrifuge with the custom-made rotors, but enlisting the programming skills of undergraduate lab associate Henry Todd. Todd, together with lab mates Martin Venturas and Yujie Wang, is  facilitating  climate change simulations of 520 combinations of 8 species in 20 sites across the country based on  six climate projections and two emissions scenarios … over 30 years.

John Sperry will not be parsing through this kind of macro data for much longer, limiting himself to just a few more papers and farewell meetings. Retirement will  allow him  more time to adventure with his wife Holly in their truck camper and to be in his  favorite laboratory: the outdoors. He and his canoeing buddies also look forward to expanding their summer-long explorations of northern wilderness, a place where you can travel over 600 miles under your own steam and not see another soul for a month and a half. Sperry is harking to the dictum: "no one on their death bed wishes that they had spent more time at work."

- First Published in OurDNA Magazine, Fall 2019