Entering Washington Park on a hot day, a sense of relief and well-being creeps over you, along with a thick canopy of shade. That shade is provided by a collection of about 2,000 trees of more than 100 different species — some more than a century old.
City Park has an even larger urban forest, with about 3,000 trees and even more varieties.
The trees of both parks tower over us, inspiring and intimidating. Once you start looking up, it’s hard to stop.
“Unlike flowers and grasses, to me, they’re just more impressive,” said arborist Neal Bamesberger, head of the Colorado Tree Coalition (CTC). “You see a tree that’s 100-200 years old, and a petunia can’t hold a candle to that.”
State Champions
Each fall, the CTC, a volunteer group working to preserve community forests, confers the title of State Champion on the biggest and tallest trees in Colorado, selecting from among 750 species. Washington Park is home to a number of State Champions, including a 90-foot high black cherry, a 70-foot high Kentucky coffee tree and two honey locusts ranging from 76 to 84 feet tall.
These champions remind us how ingenious trees are: pumping water upwards to staggering heights through their xylem (vascular tissue) — and feeding themselves with sugar manufactured out of nothing but chlorophyl, carbon dioxide and sunshine.
Ancient trees
Sonia John, curator of the Arboretum at Regis University, phased out her career as a professional artist to spend more time on trees. Nowadays, she nurtures a mini-forest of saplings destined for the arboretum in her Wash Park backyard. A former board member of the Friends and Neighbors of Washington Park (FANS), she also wrote and illustrated the eloquent “Washington Park Tree Guide,” a book that has nearly sold out at its brick-and-mortar location inside the Wash Perk coffee house.
Seven years ago, John partnered with the Denver Botanic Gardens to create the annual Tree Diversity Conference, with the mission of protecting urban forests from disease and climate change. To accomplish that, cities must plant more diverse species. And if those species are going to survive in Denver’s harsh, high-desert climate, they’d better be tough. When Denver was first settled, there were no trees — except the cottonwoods lining rivers and creeks.
True to the vision of the Tree Diversity Conference, John is impressed by hardy trees — such as the Osage oranges in the southwest section of Washington Park.
“The ones that survived are looking great,” she said.
The Osage orange species ought to be tough. It’s been around since prehistoric times. When mammoths roamed the earth, they chomped on the tree’s distinctly weird-looking, softball-sized, wrinkled, green fruit. The park’s honey locusts and Kentucky coffee trees are also ancient species dating back to the Pleistocene. They produce bizarre-looking oversized seed pods, which were popular snacks for giant sloths and other Ice Age behemoths.
The storybook elms
John said her Wash Park favorites also include “the grand old elms.” A grove of these magnificent, V-shaped trees welcomes visitors into the park at the Mississippi Avenue and Franklin Street entrance.
Standing under these American elms is awe-inspiring. Their mighty branches darken as they surge upwards, crisscrossing and forming highways in the sky for squirrels and other small creatures. The only thing these storybook trees are missing is a small wooden door for a resident gnome.
After the ravages of Dutch elm disease (DED) of the 1950s, it’s surprising that elms are here at all. Only a few thousand remain in Denver. But Denver Forestry says the trees are carefully monitored and pruned, and happily, there have been very few outbreaks of DED in more than a decade’s time.
An insider’s view
Ben Rickenbacker, Denver’s forestry operations supervisor, is another person who lives and breathes trees.
Rambling through Washington Park with Rickenbacker is a bit like hanging out with a small-town mayor. He knows everybody. He has an insider’s view of his lofty green citizens, including their age, behavior and eccentricities.
Although Rickenbacker’s official beat is City Park and northeastern Denver, he greets each member of Washington Park’s urban forest like family. He knows all their habits — good and bad.
Passing a small hawthorn tree near the center of Wash Park, he warns: “Don’t plant one of these under your bedroom window.”
Hawthorns, Rickenbacker explains, produce pretty white flowers in June but their odor is akin to cat urine.
He plucks an elliptical leaf off a young hardy rubber tree and tears it in half.
“See these stretchy strands,” Rickenbacker asks. “That’s silica.”
Passing a honey locust with feathery, compound leaves, he points out vicious, two-inch-long thorns sprouting from a scar on the trunk.
“Thorns were bred out of them for ornamental purposes,” Rickenbacker said, “but sometimes when they lose a branch, they revert to their natural state.”
Like his great-grandfather, the World War I flying ace Eddie Rickenbacker, the Denver forester has spent plenty of time aloft — but mostly in trees. As a child growing up in Kentucky, Rickenbacker avidly climbed around the woods in the local park and savored the views from his backyard tree house. More recently, he cycled in the annual Tour des Trees marathon to raise money for tree science research.
Wildlife flock to dead trees
Periodically, elderly or storm-damaged trees in the park have to be cut down and hauled away.
But “only as a last resort,” Rickenbacker said, adding that trees are cut down only for public safety reasons.
And not all dead trees are removed from the parks.
“If they are not dangerous,” Rickenbacker said, “we usually try to leave them.”
This policy is in line with recent discoveries about the importance of preserving dead trees in forests — and not only for the nutrients they return to the soil. Wildlife love them. Why? Because those bleached tree skeletons attract insects and offer plenty of hollows for nesting.
Indeed, a dead willow on the southern shore of Grasmere Lake has become a virtual high-rise condo for park birds, complete with an ongoing bug buffet. Come fall, squirrels may use the holes as storage bins for acorns. Out in the middle of Grasmere, on Monkey Island, the whitened branches of another skeletal willow provide night herons and other fishing birds with unobstructed water views.
Even more reasons to love trees
As we learn more about trees, it seems there are even more reasons to love them.
According to Psychology Today magazine, “new research shows that the sight of trees allows the parasympathetic nervous system to gain an edge, calming the entire body.”
Trees, it appears, can also calm, cool and oxygenate an entire city.
In a recent story, The Colorado Sun described the findings of a study by the US Forest Service: “Urban trees can help reduce ground-level ozone levels — and in turn improve air quality by reducing air temperature and absorbing pollutants.”
Clearly, trees are emerging as an important way to mitigate climate change.
In 2021, Denver Parks and Recreation doubled its tree-planting budget in an effort to lower the increasing temperature of Denver’s many heat islands. These highly-paved urban areas run hotter than neighborhoods with more trees and grass. According to the Environmental Protection Agency’s website, “buildings, roads and other infrastructure absorb and re-emit the sun’s heat more than natural landscapes.”
Trees, or the lack thereof, are even revealing social injustices that were once ignored. According to The Colorado Sun story, “A recent analysis by American Forests highlights Denver’s shady divide: neighborhoods of color and areas with higher poverty rates have fewer trees than those that are predominantly white and more affluent.”
On a larger scale, groundbreaking research by Canadian scientist Suzanne Simard has revealed the invisible but powerful connections between forest trees. Simard found that in old, established forests, different species of trees and fungi communicate, pass nutrients back and forth and essentially depend on each other. Many tree lovers instinctively feel that clear-cutting old forests and replanting them with one or two species is wrong. Now we know why. And that knowledge holds out hope for preserving the “lungs” of our planet.
No wonder that shady old elm is taking on a new importance. Besides, where else would a gnome feel at home?
