Deep roots
In a state that takes its name from the verdant landscape, it’s fitting that the study of plants has long been a central focus at the University of Vermont. In the nineteenth century, UVM’s first doctoral degrees were awarded to botanists. Turning forward to more recent history, the initial warning signs of acid rain’s impact on northern forests came through Professor Hub Vogelmann’s research on Camel’s Hump. As today’s scientists explore issues from invasive species to climate change to sustainable agricultural methods, the study of plants and the soil they’re rooted in remains vital to the well-being of Vermont and the world.
Rude guest
Reed canarygrass, a species native to Europe, is perfectly well behaved on its home terrain. But in Vermont and other parts of the United States the once tame forage crop is choking out native plants in wetlands, running amok ecologically.
Studying this grass as a model, Jane Molofsky, associate professor of plant biology, and post-doctoral associate Sebastien Lavergne have discovered a novel mechanism to explain the surprising conversion of some plant species from quiet neighbor at home into expansive bully in new territory.
As they report in a forthcoming edition of the Proceedings of the National Academy of Sciences, the invasive power of this grass, brought to America in the mid-19th century and many times thereafter, comes not from any one individual plant, but from its history of multiple introductions from different regions of Europe.
Over decades, U.S. farmers and others have planted the grass as livestock feed, for erosion control, and for wastewater treatment—with plants taken from places as far apart as France, the Czech Republic, and Finland. The subsequent interbreeding creates a kind of biological stacked deck: Drawing on genetic variety from across the European continent, new strains have emerged in the United States with higher genetic diversity and more potentially advantageous qualities than their species brethren across the Atlantic.
“It’s not that you’re taking the ones in France and moving them to the U.S. and they’re suddenly invasive,” Molofsky says, looking over a green swath of reed canarygrass growing in a UVM greenhouse, “it’s that you move some plants, and then you move some from somewhere else and they recombine here to form something better, genetic superstars.”
In Vermont the state invasive exotic species committee has placed the grass on its watch list. “It shows the potential to be invasive in our climate zone,” says Rose Paul, director of science and stewardship for the Vermont chapter of the Nature Conservancy. “It’s not a plant that is banned for sale or transfer,”—yet, she says, but “we’re watching it,” perhaps to follow Massachusetts, which has banned reed canarygrass.
“If you drive around in Vermont you’ll see that it has taken over whole areas of wetlands, and out West it clogs waterways and takes over irrigation ditches,” Molofsky says. “It’s a big problem in Alaska: it’s preventing salmon runs, it's changing habitats. It’s becoming a larger and larger problem.”
Molofsky’s greenhouseand field-based study, funded by the U.S. Department of Agriculture, suggests that the problems posed by reed canarygrass and other invasives will increase with climate change. In future scenarios, this adaptability will give invasive species a clear advantage over natives. For land managers, farmers, nursery owners, and others the implications are weighty as a considerable number of horticultural and agricultural plants that currently seem benign could become invasive by the same mechanism that affected reed canarygrass.
Molofsky says, “Some in the nursery industry argue, ‘well, we can have barberry here, because it’s not invasive in Vermont.’ My point is, ‘yes, not now, but keep introducing it and let it mix, and, with climate change, we’ll have it later.’”
Messages from the mountain
“This is it,” Brian Beckage says, pointing ahead to a ragged wall of small trees. Where he stands on the Burrows Trail, 2,600 feet up the side of Camel’s Hump, maple and beech trunks make towering brushstrokes against a canvas of snow. But just a few yards upslope, the ski-packed path disappears into a tangle of evergreen. “The spruce-fir transition,” he says. “It can be very abrupt.”
This change in vegetation is well-known to New England mountain hikers (and assistant professors of forest ecology, like Beckage). Here, conditions become severe enough that deciduous hardwoods, like sugar maples, must give way to boreal conifers, like balsam fir.
In 1964, one of Professor Hub Vogelmann’s enterprising graduate students, Thomas Siccama, spent days scrambling up four of Vermont’s tallest peaks, including this stretch of Camel’s Hump. On each slope, he laid out a transect through the forest, marking monitoring plots 5 feet wide and 100 feet long. In these plots, he counted trees and took note of how vegetation changed with increasing altitude.
Hub Vogelmann “caught flack from the University for the project,” recalls his son Tom, current chair of the plant biology department. “It wasn’t seen as useful.” Yet, as history reveals, this survey on Camel’s Hump was an important step in the senior Vogelmann’s now-renowned discoveries about how acid rain was damaging mountaintop forests.
In 2004, one of Brian Beckage’s enterprising graduate students, Ben Osborne, resurveyed three of Siccama’s transects. His fieldwork—and additional studies by Beckage and his students—reveal something surprising and worrisome again on Vermont’s postcard peak: Spruce and fir are in retreat. Or as Osborne’s thesis puts it, there’s been an “upward shift in the deciduous-boreal ecotone during forty years of warming in the Green Mountains.”
Before Osborne began his repeat survey, some scientists were skeptical of its usefulness, Beckage says. Despite spiking global temperatures, they wondered: Is forty years enough time for climate warming to change where long-lived trees would be found on Camel’s Hump?
“On one transect, we’ve measured a ten-to-twelve-meter shift,” Beckage answers, fingering the yellowing needles of a stubby spruce. His theory about this rapid migration ties back to Hub Vogelmann and Thomas Siccama. “Acid rain damaged trees, creating openings in the forest canopy,” Beckage says, and this might have accelerated the hardwoods’ uphill push.
“Unless we slow the rate of climate change or stop it altogether,” Beckage says, “more tree mortality and large shifts in forest composition are possible.” And alpine trees, ultimately, reach a point where they can’t retreat any higher—the top of the mountain.
Research on the road
Two weeks, four thousand miles, countless Atlantic coast beaches from Cape Cod to the Gaspe Peninsula, 2005 was David Steakley’s summer of Hudsonia Tomentosa. For the benefit of those who didn’t major in plant biology, the UVM senior describes the plant as a common New England beach grass, a “dumpy weed” most of the year that blooms each June for two weeks of yellow-flowered glory.
On the strength of a HELiX (Hughes Endeavor for Life Sciences Excellence) grant, Steakley hit the road to collect geographically diverse samples of the plant, then returned to spend the rest of his summer analyzing their DNA in a UVM lab. His intent was to answer questions regarding Hudsonia’s migration during the Pleistocene ice age. Though the results were “kind of frustrating” in Steakley’s estimation because the genetic diversity was not what he’d expected to find, such seeming dead-ends are an important lesson of the research life.
The summer 2005 experience was part of a solid run of research Steakley has undertaken since first connecting with Professor David Barrington in his freshman year biology class. In addition to his own work on the Hudsonia mysteries, Steakley has worked in Barrington’s lab assisting with the professor’s fern-focused research.
It’s solidified a path to an academic career for Steakley, who is weighing grad school offers from Cal-Berkeley, Johns Hopkins, and others.
Asked what working with Barrington has meant to his development as a scientist, Steakley’s eyes spark. “Oh, man, your mentor is so important. Dave’s always here; his door is six feet from my desk in the lab. I can talk to him about anything anytime.”
—Thomas Weaver
Fungal fighter
The eastern hemlock is in trouble. From Georgia to Maine, this once-mighty conifer is now succumbing to an exotic pest, hemlock woolly adelgid. First detected in the western United States in 1924, the adelgid caused little damage. But when it was carried east and reached Virginia in the 1950s it began its destructive spread. An aphid-like insect, the adelgid kills eastern hemlocks within a few years after infestation, feeding on the sap at the base of their needles and cutting off their nutrients.
It’s a pressing problem: In Shenandoah National Park most of the famous towering hemlocks are now dead. The adelgid has ravaged parts of Kentucky, North Carolina, and the Smoky Mountains. Expanding northward, it has moved through Massachusetts into southern Maine and New Hampshire.
The only natural deterrent to the adelgid seems to be a very cold winter. With global warming, their northward spread seems inevitable. Though not officially recorded yet, “it’s probably in southern Vermont now at population levels too low to easily detect,” says Scott Costa, research assistant professor of plant and soil science, who anticipates that the adelgid will be into the Champlain Valley in not too many years.
New research in UVM’s department of plant and soil science, though, could aid the hemlock’s survival. Last December, Costa, graduate student Stacie Grassano, and two other researchers, Vladimir Gouli and Jiancai Li, submitted a provisional patent for a new method of cheaply and effectively spreading a strain of fungus called Lecanicillium muscarium, and other similar biological controls, that might beat back the adelgid without having to use expensive, toxic pesticides. They call their approach a “whey-based fungal micro-factory.”
Instead of growing fungi in a conventional factory and then transporting it out to a forest—a costly proposition—their factory will be the forest. Or, more accurately, tiny droplets of sweet whey—a cheap waste product of cheese production, inoculated with the right concentrations of the target fungus—will be their factory. By spraying the whey solution into an infected forest, they believe they can get the adelgid-killing fungi to reproduce in large numbers on its own.
Costa and Grassano’s experiments on branches taken from adelgid-infected forests in Massachusetts are proving highly successful, with rapid growth of the target fungi out-competing other fungi that live on hemlocks. If their laboratory tests continue to go well, the researchers anticipate starting field trials in 2008.
The economy and ease of the UVM team’s whey micro-factory technology might prove a critical consideration for land managers—especially in large areas with low economic value, like wild hemlock forests.
“We’re not going to eradicate the adelgid,” Costa says. “The best-case scenario for insect-killing fungi is you inoculate the environment and get disease outbreaks to start cycling. The idea is to reduce the pest population to a level that is manageable, allowing some of the trees to make seeds, grow, and survive.”
Looking into the light
The long-term forecast: more gray days. To the dismay of beachgoers and wedding planners, global warming will likely spawn an increase in worldwide cloud cover. But plants won’t mind.
“Cloudy days are good for plants,” says Tom Vogelmann, chair of the plant biology department, “they photosynthesize better in diffuse light.” As an example, Vogelmann describes how the eruption of Mount Pinatubo in 1991 blasted light-scattering particles into the atmosphere. Recent research shows that following this volcanic haze, photosynthesis rates in forests increased.
When skies are clear, he explains, sunlight comes straight down in parallel rays and is absorbed in the topmost leaves, while lower down remains in shade. When skies are cloudy, light bounces in from many directions, evenly illuminating more leaves and penetrating deeper layers of forests.
“We now know the canopy as a whole is more productive in diffuse light,” Vogelmann says, “but there is also the little-understood question of how individual leaves respond to diffuse light and that is what we’re looking at in my lab.”
Vogelmann comes at this question not just as a plant physiologist, but also an inventor. “This is a one-of-kind instrument; there is nothing like this anywhere,” he says, pointing to a pair of aluminum spheres hooked to powerful xenon lamps and several transformers and recorders.
Vogelmann and his technician and graduate students call the machine they have painstakingly created the “diffilator,” though in the more sober narrative of grant applications it’s described as a dual-beam integrating sphere spectrophotometer. By any name, these spheres are the only place in the world where scientists can precisely measure how much diffuse light a leaf is absorbing.
“The spheres—they’re flagpole tops, really,” Vogelmann says. “We bought quite a few from Fred’s Flag’s and Fred keeps sending us letters congratulating us on our patriotic efforts.”
Except for the potted plant in the corner, the professor’s lab seems more James Bond than botany. Aluminum rods hold lenses in the air, ready to guide incoming beams to a nearby microscope from red, blue, and green lasers mounted around the room; a slightly ominous, gold-colored sphere is attached to a stripped-down slide projector; cables and glowing metal boxes abound.
“I’m a self-taught widgeteer,” the professor says.
And a fine one it’s clear. Having received repeated grants from the National Science Foundation’s instrumentation development branch, Vogelmann’s machines allow scientists to look more deeply into the ancient mysterious marriage that sunlight performs—gathering six carbon dioxide molecules with six water molecules to yield plant sugar and oxygen—even when its cloudy.
Dirt under their nails
Seedling by seedling, garden by garden, the students in UVM’s Horticulture Club are making the campus and Burlington greener (not to mention yellower, redder, and pinker) places. Evidence of the club’s work begins right outside Hills Building, where flower gardens brighten the small quad formed by Hills, Stafford, Aiken, and the University greenhouses. The students take their work off-campus with flower beds outside the Burlington Police Station and annual efforts such as growing and distributing spring daffodils to local elder care centers. A new initiative the club began last fall put a coffee plant in the hands of every first-year student.
Mark Starrett, associate professor of plant and soil science, has been advisor to the Hort Club throughout his ten-year career on the UVM faculty. During that time the club has twice earned recognition from the American Society of Horticulture as the best small collegiate club in the nation, a prize they’ll be in the running for again this year.
Starrett’s commitment to this aspect of his teaching is driven by belief in the virtues of experiential learning. “It really gives students that practical experience you can’t get in a three-hour lab, where the situation is very prescribed and the outcome can be somewhat anticipated,” he says. “That doesn’t show you what real life is. When you have plants in a greenhouse and something is going wrong, you’ve got to figure out what’s going wrong.” Starrett cites projects such as the spring bulbs for elders or coffee plants for freshmen as providing experience with the challenge of nurturing thousands of plants and meeting a strict deadline. “If you were a grower producing these kinds of things for sale,
you would have to know how to time things right and really do it.”
—Thomas Weaver
Keeping it clean upstream
The production of steel leaves a waste product that looks like gravel. The production of milk leaves a waste product just to the south of a cow’s tail. If Aleksandra Drizo is right, a water pollution problem caused by the second—phosphorous from manure and other farmyard runoff—might be greatly improved by a meeting with the first—steel slag.
“These filters remove about 85 percent of the phosphorus, require no energy, and they’re inexpensive,” says Drizo, research assistant professor of plant and soil science who directs UVM’s Constructed Wetland Research Center. She prys the lid off a clear tube that looks like a cross between a missile and a fish tank that needs cleaning. Inside, a packed column of pellets—slag from a Quebec steel mill—is treating wastewater flowing in from UVM’s Paul Miller Dairy Farm just up the hill.
Each day, about one thousand gallons of wastewater from the farm’s dairy parlor and feedlot flow down a gentle slope next to Spear Street and, eventually, into Potash Brook and Lake Champlain. But the water makes a critical detour before it hits the brook: it’s piped through concrete tanks—constructed wetlands, planted with river bulrush—where the majority of the organic waste and, to a smaller extent, nitrogen are removed by percolating through gravel and by the biological activity of the plants and microbes.
But the wetland does little to filter phosphorous, a plant nutrient that contributes to algae blooms; it’s the most serious pollutant in Lake Champlain, yet there are few technologies available to deal with it. Which is why Drizo has, since 2004, focused her major research on steel slag filters and barriers technologies.
She’d like to see her filter and patent-pending barrier technologies widely accepted not just for upgrading constructed wetlands and retention ponds, but also in numerous places where phosphorous is a problem, like urban stormwater drains. “In Vermont, it’s not only the farmers who pollute; we have to take care of urban runoff and stormwater treatment,” Drizo says.
(for UVM staff)