In the fall, as the leafy giants of City Park gird themselves for winter, they put on one last magnificent show of scarlet, russet and gold.

Denver Parks and Recreation forester Ben Rickenbacker and his 12-person staff also gird themselves, because winter is pruning time. That’s when men and women, mostly young, strap on up to 30 pounds of equipment — including chainsaws, handsaws, ropes, blocks and pulleys — and prepare to climb as much as 100 feet to minister to the needs of towering oaks, elms, lindens and the many other species that populate Denver’s urban forest.

In the fall, deciduous trees slow their production of chlorophyl, shed their leaves and begin to go dormant for the winter. That’s the best time to prune, according to Rickenbacker, because without their leaves, “you can really see the structure.” Dormancy also lessens the chance of accidentally spreading diseases like Dutch elm or fireblight.

Pruning is essential for landscape trees, since they co-exist with people. Removing deadwood and coaxing trees into structurally sound, balanced shapes is essential for their health — not to mention the safety of wandering pedestrians. But Rickenbacker and his colleague, Urban Forestry Inspector Paul Cancik, frown on bucket trucks, which make it difficult to reach dense interior branches.

“It’s better to climb the tree,” Rickenbacker said. “But it’s a dangerous job. You can be 60 feet up with a chain saw inches from your leg.”

Added Cancik: “You have to be a real athlete.”

Forestry’s Operations Division routinely practices aerial rescue.

“One employee dislocated his kneecap when swinging between branches,” Rickenbacker recounts, “and couldn’t make it down on his own.”

The pampered trees of City Park

As forestry operations supervisor, Rickenbacker and his crew are responsible for the care of 82,000 park and parkway trees. Cancik is with the Forestry Inspections Division, which watches over 230,000 “right-of-way” trees planted along Denver streets. When not pruning, the foresters make their rounds with wooden mallets and probes to check for internal decay.

City Park is a demanding charge. Built in 1882, the Beaux Arts era-park sprawls over more than 320 acres and houses the Denver Zoo and the Denver Museum of Nature & Science. The park is home to more than 3,000 trees and hundreds of different species. Pampered by irrigation, many of the trees grow much larger than in the wild. Every fall, some earn the title of State Champion from the Colorado Tree Coalition (CTC), a volunteer group working to preserve community forests. The group selects from among 750 species.

According to the CTC’s Neal Bamesberger, City Park is currently home to five State Champions — including two pine varieties over 65 feet high. In fact, this urban preserve has so many large, old trees that a decade ago, Parks & Rec considered turning the park into an arboretum. The arboretum map, offering a self-guided tour of 70 trees, is still available online at City Park Arboretum Tree Walk.

Leafy eccentrics, large and small

There’s a lot for tree lovers to choose from in City Park.

“Possibly the most spectacular — and underappreciated — tree feature in the park is the Robert More Pinetum,” said horticulturalist Sonia John, curator of the Arboretum at Regis University.

A preserve of 120 conifers southeast of the Denver Museum of Nature & Science, the little-known Pinetum (pronounced: pie-NEE-tum) has no sign marking the entrance, no paths and no labels on the trees. But if you descend from the museum’s southern terrace down a set of broad steps, you’ll find yourself surrounded by pinion, ponderosa, mugo and white pines along with three types of juniper, and white-and-blue spruce. There are even some bald cypress — a species that often grows semi-submerged in the bayous of Louisiana.

Not all the park’s conifers have survived the city’s 2004 switch to irrigating with recycled water. The higher salt level in this water has been particularly tough on conifers, since they can’t rid themselves of excess salt by shedding their leaves. But one tree that appears to be thriving is a 67-foot State Champion red pine east of Ferril Lake, in the south-central section of the park. Red pines, the state tree of Minnesota, actually prefer sandy soil with low nutrients — which makes them well-suited to the harsh, high desert conditions of Denver.

Can a tree that’s only 17-feet-high qualify as a State Champion? That seems unlikely, except in the Kingdom of Lilliput. But what it lacks in size, the park’s State Champion yellowhorn makes up for in durability. Native to northeastern China and Korea, the yellowhorn is currently thriving in an un-irrigated southeastern section of the park. The yellowhorn’s fruit, which resembles an exploded baseball, contains so much oil it has stirred interest as a biofuel. Most of the tree is edible, including the seeds. Rickenbacker and Cancik compared the flavor to macadamia or hazelnuts.

Rickenbacker and Cancik are also impressed by Japanese pagoda trees, including a 65-footer on the park’s east side, which has a full, rounded shape, bright green compound leaves composed of 10-15 leaflets and not one, but five, thick, sinuous trunks.

“It’s one of the few trees to flower in late summer,” Rickenbacker said approvingly. He eyed the pagoda tree’s generous assortment of trunks. “If these were all one trunk instead of five, this would definitely be a State Champion.”

Nature Play

As in Washington Park, City Park foresters try to preserve dead trees that don’t threaten to fall on people. Since there is no public access to the island in Duck Lake, several dead trees were left upright, where they provide a rookery for nesting cormorants. Forestry also supplies logs and branches to the Denver Zoo, where tree-munching animals like giraffes and zebras use them as “browse.”

A dead maple’s upright skeleton will also play a nurturing role — but for children instead of animals. In an unusual partnership between Parks & Recreation and the Denver Museum of Nature & Science, the small playground in the park’s southeastern quadrant will be re-developed with a new focus on natural objects for kids to explore. The City Park Nature Play & Waterway Restoration project will span three and a half acres, and with plenty of logs and boulders for climbing. Water will once again flow through the park’s historic DeBoer waterway, constructed in 1953 but dry in recent years. The revived waterway will offer stepping stones, bridges and sandy “beaches” — guaranteeing play that’s not only natural but satisfyingly messy. And just to cover all bases, there will also be traditional swing sets and slides. Construction is slated to begin next year, in time to open the new play area for the spring of 2023.

A nearby tree might just bestow good luck on the project. In the northeastern corner of the old playground, stands a tall catalpa, with floppy, heart-shaped leaves and seed pods resembling green beans. There’s something a little magical about catalpas, which perfume the air every spring with huge clusters of sweet-smelling flowers. And the magic doesn’t stop there.

“About 12 fairies live up in the tree,” reported a Life on Capitol Hill reader recently. “Look for the scar on the trunk, then look up 15 feet.”

If you do, you will discover that foresters are not the only ones who climb trees in City Park.

The new nature-based playground will preserve the fairy wishing tree. And park visitors who wish to honor this Gaelic tradition can continue to leave offerings for the resident tree spirit.

Is this at odds with the concept of a science-based playground? Perhaps not. The very idea of fairies — with their acorn hats and cobweb garments — was probably inspired long ago by fascination with the natural world.

Exactly the sentiment Nature Play hopes to inspire in kids.