Ensuring Duke Stays Ever Green

As one building boom follows another, this university in the forest works harder to preserve and expand its tree canopy.
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October 20, 2016

Walkers and runners on East Campus stopped in their tracks last summer at the sight of massive chunks of oak tree trunks on the ground. Duke had hired arborists to cut down the giant trees to make room for a new softball field, and the regulars who circle the public trail around East each morning did not approve.

One distraught woman paced near a fence erected by the cutting zone, smart phone pressed to her jaw. Her words weren’t audible, but the bad news she was sharing was obvious.

Willow oaks. Big ones. Gone. For good.

To many in Durham, those oaks simply belonged where they were. Eighty years in the making, they showed a majestic girth and height that were stunning from any angle all times of the year. Losing them stung.

More big and beautiful trees will fall on East and West campuses, victims of old age or the need to make room for the next landmark building.

Decades of construction at Duke have produced countless benefits: jobs for housekeepers and Nobelists, hospital beds for emerging cancer care, research of all scientific stripes, classrooms, lecture halls, art galleries, athletic fields, and on and on. But new building footprints also shrink the amount of ground available for the trees that have always softened East and West.

Well aware of this growing conflict, people with the prodigious task of tending Duke’s greenscapes are focusing on the green that remains with new intensity. While they manage the decline of parts of a tree canopy established in the early twentieth century, they are developing, with a new sensibility, what will replace them in the twenty-first.

IN THE FOREST

In its master plan documents since 2000, Duke has described itself as “A University in the Forest” for good reason.

Duke Forest—a mix of research plots, open-air classroom, and public trails—covers 7,000 acres, so much land that it extends out of Durham County into nearby Orange and Alamance counties. Among the active studies is a project probing ways that climate change affects soil fungi diversity, a topic that may sound ho-hum but is meaningful to plant health globally.

Between East and West, the meticulously maintained Sarah P. Duke Gardens remains what The Huffington Post once called an “insanely beautiful public garden.” More than 400 tree species stand within, from native hawthorns and magnolias to Asian imports such as dawn redwoods and Chinese yellowwoods.

Planting and preserving trees on Duke’s main two academic campuses has been a priority since the university’s founding, says Mark Hough, Duke’s landscape architect. Since the 1920s, Duke has hired experts to help with that mission, starting with the Olmsted Brothers Landscape Architects, led by the sons of Frederick Law Olmsted.

“There’s always this backdrop of trees,” Hough says of Duke as a place. “It’s the setting. It’s the character. It’s the continuity. It’s the thing that stays the same when a road or building gets built.“

On East Campus, Duke landscape planners, starting in the 1920s, expanded upon what the former Trinity College started on that property, Hough says. Pine trees, oaks, and other hardwoods on the perimeter create a city-park-like feel. The crowns of the oldest willow oaks there today are nearly as wide as the trees are tall and creeping toward the end of their lifespan.

West Campus’ historic Gothic campus, on the other hand, was carved from forest, just a fraction of the land James B. Duke purchased west of Durham. Elms, oaks, and magnolias there were aligned more formally, spaced tastefully on the edges of the grassy open quadrangles at the center of Collegiate Gothic architecture. Aerial photos into the 1940s show the still-new West Campus nearly encircled by dense forest.

Duke today remains greener than many urban university campuses, Hough says. Colleagues visiting from other colleges always say so. The Arbor Foundation last spring gave Duke its Tree Campus USA designation for the eighth year in a row.

But there is decidedly less room for green. What in 1930 was an institution hosting buildings with 2.3 million gross square feet, by 2015, held 18.5 million square feet and growing. It’s a sure bet more is to come. A tree canopy that once might have seemed inexhaustible has been trimmed in ways that Duke’s founders likely may have never imagined, Hough says. “They had all the land they thought we’d ever need, all the trees they thought we’d ever need.”

GROWING PAINS

Expansion at Duke, like at a lot of university campuses, really kicked off after World War II to make room for GI Bill-toting students and research relevant to the Cold War era. Red-brick physics and engineering buildings were raised north of the campus’ Gothic core, followed by a string of construction projects that built a dense and active hive of laboratories nearby, a new law school, a business school, and many a parking lot.

The university brought back the Olmsted Brothers firm to help plan the growth. In the late 1950s, the firm recommended keeping a greenbelt of forest “of not less than 150 feet in width” circling the boundaries of the original West.

Today, sizable swaths of forest remain on approaches to campus, especially on Cameron Boulevard and Duke University, Towerview, and Erwin roads. Very little forest survived the buildup that produced the mini city that is Duke’s medical campus behind Davison Building. The same goes for an expanded athletics district.

The greenbelt, in other words, has become fragmented, too fragmented in the eyes of some. “It’s only recently that when you take a look at what is left, and hey, it’s not as much as we think,” Hough says.

In 2014, students and faculty sounded a loud alarm over threats to what long has been called Anderson Woods. Duke announced plans for a 70,000-square-foot student health-andwellness center on the West Campus parcel off the Towerview Road parcel, across from the Sanford School of Public Policy and woods adjacent to Cameron Indoor Stadium. The location, a short walk from the Bryan Center and most West dormitories, made perfect sense in important ways.

But protecting Anderson Woods made sense, too. Unlike most of Duke Forest, which rose on land once farmed for cotton or tobacco, the five acres of oak and hickory forest shelters old forest at least 300 years old, a rarity in North Carolina’s Piedmont. Rich, undisturbed soils have supported more than twenty species of trees and more than 100 varieties of other plants.

Lewis E. Anderson, who joined Duke’s faculty in 1931, recognized the value of the forest remnant early on. For decades, he promoted its use as an outdoors classroom and for research, and in the 1960s and 1970s, he helped preserve it as development edged near. Data collected over forty years in its interior on the size, age, and variety of plants and animals in the woods remain in use. Students in the “Ecology for a Crowded Planet” course, taught by ecologist Emily Bernhardt and biologist Bill Morris, have used measurements taken within the woods to estimate changes in tree species and determine the stuamount of sequestration in carbon plant life.

When it became known that a share of the woods could be bulldozed, the Graduate and Professional Student Council passed a resolution calling on the Duke board of trustees to step in. It began: “Whereas, Duke University defines itself as a “University in a Forest…” and urged trustees to permanently preserve Anderson Woods, along with nearby Chapel Woods, the forest tract behind Duke Chapel.

Norman Christensen, founding dean of the Nicholas School of the Environment, also voiced concern. When Christensen took cores from the trunks of the woods’ big pine trees after they died in the 1980s and 1990s, the rings revealed they were 240 to 290 years old. Long an admirer of Anderson, Christensen tried unsuccessfully to have the woods named for Anderson, its protector, after his death in 2007.

“For me one of the key things was the accumulated data on a particular place. It makes them, from a scholarly point of view, like a rare book. You don’t want to lose that,” Christensen says.

University planners, already far along in design and launching construction, did not cancel the project. But they reduced its reach into the research plot in the woods. A retaining wall was moved twenty-five to thirty feet closer to the building. An evergreen hedge will be planted to prevent more light, a welcome mat for invasive plants, from penetrating the interior.

And very much to the satisfaction of Christensen, Hough, and others, Duke’s trustees voted to formally protect what remains of what is now officially called Lewis E. Anderson Woods. After word circulated that it was being eyed as a location to host a new engineering building, the trustees did the same for Chapel Woods. Moves are also afoot to assess ways to improve that tract’s vitality.

Christensen and Hough are active now in an effort to better document the assets provided by the remaining canopy on East and West campuses. It would give university planners more data with which to weigh gains and losses when selecting the next building site.

A draft “tree priority” map identifies Anderson and Chapel Woods as protected. Areas of ecological importance, including West’s multiple hollows and streams, will be noted. So likely will be campus “gateways,” wooded approaches to campus on Towerview Road on West or Campus Drive on East, for instance.

“It’s really hard. If you want to put up a building, you either have to build on a parking lot or forest,” says Christensen.

It’s not only natural and academic benefits that make some trees precious. So do cultural intangibles, says Christensen. For instance, it’s no accident that none of the north-facing windows of the Goodson Chapel in Duke’s divinity school hold stained glass. The sight of seasonal changes in Chapel Woods is decoration enough.

“People’s eyes have been open to the fact that this is a resource that’s not going to be here unless we expect it to be,” Hough says. “You can’t approach this by saying we’re going to prevent construction. You want to evaluate what is left.”

TRUNK BY TRUNK

Today’s drive to better understand, protect, and restore Duke’s treescapes was born, in part, from a recognition of risk. Trees, especially very old and very large trees, can be perils on college campuses.

In 2013, a UNC-Chapel Hill senior died after an oak crashed and hit her outside her Franklin Street sorority house as she rushed to escape a storm. Just last year, ten people on a Vanderbilt University admissions tour were hurt when a hackberry tree toppled on them.

The danger came home to John Noonan, Duke’s vice president for facilities, in 2011. That year, a sizable willow oak fell during a rainstorm and landed on a car driving east on Campus Drive, flattening part of its frame to the ground. One passenger was hospitalized.

Noonan’s staff, with help from student interns, got to work assembling a more precise census of trees on East and West campuses, especially the condition of those near where people walk, drive, study, and live. “We have tried to go from being ad hoc to being more systematic and strategic,” he says.

Working during summers when it’s easiest to identify a tree species, teams equipped with specialized software on iPads have inventoried more than 14,000 trees since 2014. Digital mapping and GPS allowed Noonan’s staff to create linkable dots for each tree in the inventory on aerial images of both campuses. Click a dot in the mapping program and a profile pops up of a tree’s type, height, trunk diameter, risk factors, etc.

Noonan’s staff also created priority zones for tree inspections and maintenance. Areas where a falling limb could do the most harm get the most attention, with single walkways leading to multiple buildings, roads, bus stops, child-care centers, quads, and the park-like land circling East Campus among them. Specimen trees, the hardwoods and the pines planted strategically on East and West, also get particularly close attention.

The tree-trunk inventory enables Duke to keep better track of how many are taken down versus how many get planted. From 2014 to last July, 3,339 trees were removed and 3,320 were planted. Another 1,082 plantings were scheduled as of last summer at thirteen construction sites, including the softball field on East and the Student Health and Wellness Center on West.

When those projects are done, the managed trees census will reach 15,200 trees, Noonan says. “We’re developing a framework to help us think things through more systematically.”

The census also supports a campus initiative to reuse wood, rather than burn lots of petroleum to drive all the stumps, trunks, and branches taken down to landfills. Over the past two years, 743 trees were milled for lumber, including some native red oak set aside for interiors in the wellness center. Most of the remaining trees were chipped for mulch or donated for firewood. For those who want to hold some old Duke wood, the Duke Stores sell Duke Quad pens, honed from an eighty-year-old willow oak that aged out on a West Campus quad.

Andrew Currin, an arborist and Duke’s campus horticulturist, uses tree census data year-round. Near the Main Street entrance to East Campus, where no new building is planned for now, Currin’s goal is to keep the oldest specimen trees, those planted in spots intended to show off their shapes and scales, intact as long as possible.

Campus staff or contractor arborists don’t just look over the older trees to detect disease, decay, and deadwood or hammer their trunks or root buttresses to probe for weakness. Sometimes they hook up tomography devices that transmit sound waves through the center of a trunk to detect hollowness from decay. They get on lifts to look over the top of crowns or use air spades, devices that clear dirt without doing harm, to allow good looks at roots.

But they can’t make a tree live forever. After lightning struck one of the elder willow oaks near the southeast corner of the East Campus wall last year, Currin waited, hopeful it could endure the blow. But the next spring nearly a quarter of its crown didn’t leaf. By summer it was clear the oak was weakening and had to be taken down. By August, all that survived of it was a low stump as wide as a kitchen table.

Currin never savors felling a tree. And he knows for certain it will upset other people. He and crews with tree companies Duke hires get yelled at, even accused of “waging war” against the old trees, when saws get fired up, Currin says. “People notice when we cut a tree down. People get all kind of emotional, which I understand. But I can’t recall a time when anyone said anything when I planted one.”

PLANNED SPACES

As construction of new landmark buildings gobbles up more land on East and West campuses, Hough has helped shepherd what he and Noonan call “planned places.” On the plaza outside the Bryan Center, drought-resistant Chinese elms shoot out of containers, delivering dappled shade and filling in a smidge of the fragmented greenbelt. It took cranes to deposit sizable bald cypresses near West Union between the elms and nearby Anderson Woods.

“A designed landscape can provide enough trees that you connect the canopy,” Hough says. “These pick up the woods that used to be here.”

A campus map now counts more than seventy such planted destinations, both historic and recent. Newer are terraces by surgery and cancer treatment centers in Duke Medical Center and the pedestrian way that links Bostock Library to the Fitzpatrick engineering building. A landscaped Blue Devil tailgating plaza is in the works for the walk from Cameron parking garage to a renovated Wallace Wade Stadium.

Yet none of those may match the potential impact of Duke Pond, a 12.5-acre site finished last year that integrates the ecological and the aesthetic on a scale the university has never tackled before in Durham.

Located where Towerview and Erwin roads meet, the water body collects a fifth of West Campus storm water runoff that is piped and otherwise flows into the pond. A share feeds a chill plant that pumps water across campus to cool buildings, reducing the need to use Durham’s treated municipal water by a hoped-for 100 million gallons a year.

But this is not one of those sterile retention ponds dotting suburban apartment and mall developments across this country. It’s a biocleanser intended to improve water that eventually will flow from the pond via a spillover into Neuse River and the Cape Fear River watersheds.

An underwater weir collects sediment flowing in, reducing the risks it will sully water downstream. Wetlands plants absorb some of the phosphorous from fertilizer washed in, turning it into food for the plants rather than disruptive nutrients in river basins downstream. It’s also a public space, with timber from the hundreds of trees harvested from the site used to build a pavilion, a boardwalk, and a bridge. A nearly mile-long walking path and a lawn amphitheater are meant to beckon activity.

The design is not as formal or decorative as other Duke landscaping projects. But it integrates more modern concerns, including a desire to help natural resources enrich a habitat.

“On the north side, the idea is that it will become a forest-edge path that would be a walk through the woods where you look down to a pond. Some plants will thrive. Some will suffer. It will morph and merge,” Hough says.

Duke Pond is also a native plant preserve, home now to 41,000 plants, including forty varieties of trees. If they make it, the young water tupelos and sycamores one day could be 100 feet tall. White oaks there may live hundreds of years. Hough hopes the resulting ecology will draw teachers and researchers, the way Anderson Woods has for so long.

“There is not a lot of structure. If this had been a twentieth-century Duke Pond, it would be more manicured. I think there was less tolerance for messy back then,” Hough says.

TO THE FUTURE

Back on East Campus, oak trees still stand between the public trail and the softball field construction site. The smaller trees are lovely, but they lack the bulky, asymmetrical spread that made the larger oaks, now gone, unforgettable. More trees were lost on East this summer, including skyscraper pines that had stood a bit to the south, to make room for a new dormitory. Some clearly were aged. A hollow tube inside the trunk of one was big enough to be visible from a parking lot across Broad Street.

Still, not all is loss. At Duke Pond, the softer earth on the still-new trail is easy on the feet. And the open space, rare in an area where tall pines tend to hem you in, pleases the eyes. Trees there, hugging the slopes and standing in the water itself, are low and young enough that the new woodland can feel spare, but it’s easy to see that one day this could grow into a landmark wood that, like the giant oaks lost on East did, will look like it belongs there.

Trees on East and West campuses, especially the old specimens planted before World War II, will continue to disappear, victims of old age or construction schedules. On West, the fragmented greenbelt surrounding the original campus may continue to thin.

What a relief that something new also is taking root.

Clabby is a writer and editor who lives in Durham.


Pretty and productive

Trees on college campuses soften the view during a walk to class and throw precious shade during summer session. But they do so much more. Trees improve the spaces we share. Science calls that ecosystem services, although it’s not a stretch to call it life support. Consider this:

Trees need carbon, along with sunlight, to produce the chemical energy that lets them thrive and grow. To stoke these biological power plants, leaves harvest carbon dioxide from the air and then store carbon in the wood. Hundreds of millions of years old, this cycle is more valuable to us than ever. It offsets the warming effects of the CO2 our industrial smokestacks and tailpipes release that are changing Earth’s climate.

Other impacts are much more local. Paved ground absorbs and releases heat, warming air above by two to eleven degrees. Tree shade lowers temperatures, especially in the urban heat islands. Even the interior of buildings shaded by trees benefit, requiring less air-conditioning than buildings that are fully exposed to the sun.

Roots keep the ground around trees porous enough to absorb storm water, a first step in cleaning oily runoff from busy streets or chemical-tainted lawns. They reduce noise and expand habitats for birds and other wildlife. Branches help out, too, capturing some of the tiny particles engines and power plants spit out with soot that can harm people’s hearts and lungs.

Scientists now say the health benefits of living near trees are measurable. One Danish study observed that having ten more trees in a city block, on average, improved a person’s perception of his or her health not unlike a $10,000 increase in annual income or being seven years younger. Having eleven more trees in a city block, on average, decreased incidence of diabetes, heart disease, and stroke comparable to income boosts of $20,000 or being 1.4 years younger.

It’s important to note that not everyone has equal access to these benefits. Three Duke Nicholas School graduate students, Gregory Cooper, Anne Liberti, and Michael Asch, released research this year that indicates more affluent neighborhoods in Durham are more likely to be leafy, a finding that is consistent with research conducted elsewhere. —Catherine Clabby