On a foggy October morning , Duke Landscape Services’ Superintendent of Tree Management Roger Conner met a tree service team to begin a day of examining some of the most treasured pieces of campus.
The willow oaks that have towered over the heart of West Campus for around nine decades are approaching the far edge of the life expectancy, and it’s time for what is essentially their annual check-up.
“They’re just like people in that you have to look at their symptoms,” Conner said. “Just like you look for symptoms for COVID or the flu, you have to look for symptoms on the trees.”
For the past 12 years , Duke has been honored by the National Arbor Day Foundation for its stewardship of the trees on campus. With around 60 percent of campus covered by trees, Duke lives up to its reputation of being a “university in a forest.” Duke plants trees each year to offset some of the loss of tree canopy due to campus expansion and tree removals.
Once a year, Duke conducts assessments of the trees in different areas of campus. This consists of visually inspecting each tree and doing more in-depth evaluations of trees which show concerns of older trees, such as the nearly-century old oaks in the heart of campus. This fall, the trees in the core of West Campus and the area around Duke University Hospital received evaluations.
So from the magnolias that spread out in front of Davison Hall to the red buds and dogwoods that color the approach to Duke University Chapel, every tree will get looked at, logged in Duke’s landscape inventory and accounted for in the maintenance plans for Landscape Services.
But a less-visible part of Duke’s commitment to preserving its canopy is ensuring the roughly 17,000 inventoried trees already growing on the landscaped parts of campus remain healthy. And a major piece of that effort are days like these, when experts gauge the health of Duke’s trees.
“We want to keep them healthy because, with everything the trees do for us, we want to do everything we can to protect them and the environment,” Conner said.
“Some of these may be a three-second look, some may be a 360-degree walk around the tree,’ Conner said. “The older the tree, the more attention they’re going to get because younger trees have less symptoms. As we see things that have to be done, we will cater our maintenance accordingly.”
The visual inspections can spot cracks or worrisome leans, which can hint at structural failures inside the tree, or branches that are dead or dying, which could become hazards should they fall. They can also discover fungus growing at the base of the tree or on the bark, which could be a sign of decay inside the trunk.
The solutions to these issues can involve pruning dead branches, treating the tree or the surrounding soil with different fungicides or fertilizers, or in extreme cases, removing the tree.
Conner and a two-person team from Bartlett Tree Service start the day by looking at an old oak in a corner of Clocktower Quad. Bartlett Tree Service Technical Specialist John Colavecchio begins by tapping the trunk of the tree with a rubber mallet, listening to differences in the sound the taps make.
He then hammers in a series small probes around the circumference of the tree, connecting each to a computer with small wires. Called a sonic tomograph, these sensors use sound waves to gauge the density of the wood in the trunk.
“This will give us a visual representation of the inside of the tree,” Colavecchio said as he looks at a computer screen coming alive with a colorful depiction of the sound readings.
Colavecchio spots what appears to be a crack that juts deep into the trunk. In a tree that’s likely around 90 years old, cracks such as these are expected, but not a cause for too much concern. Other than that, the tree appears to be in good shape.
1. Duke maintains about 17,000 trees on campus, spanning 500 acres of its 1,300-acre campus.
2. Trees require a check up where experts evaluate their health.
3. Duke has a schedule and standards for how trees are maintained. Trees on East and West Campus and surrounding the Medical Center are assessed every three years.
4. There are three different levels of tree assessment including a walk-by of trees looking for signs of concern, soundings on the trees to pinpoint weak wood or decay, sonograms on trees to measure decay and structural integrity.
5. For every sick or dead tree removed, Duke tries to put a new one back in.
The oak has seen decades worth of students moving in, moving out, going to class, celebrating graduations and savoring championships. And by the looks of it, the tree should be able to bear witness to much more.
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