A child climbs on a cherry blossom tree along the Tidal Basin. (Andrew Harnik/AP)

With peak bloom in full swing in the District, tourists and locals have descended upon the Tidal Basin to walk and take photos among the cherry blossoms. But to some of the visitors who might be there to pluck the blossoms or pose on the branches, the National Park Service has a message: Don’t.

“The cherry trees are truly special and they’re very fragile,” said Bob Healy, an NPS park ranger of 34 years.

This is Healy’s 19th Cherry Blossom Festival and part of his job is educating the festival’s annual 1.5 million visitors on how to enjoy the famous trees without damaging them. Last Sunday, Healy staffed an information booth at the Tidal Basin where visitors can receive a Cherry Blossom Protector badge by taking an oath to protect the trees.

Healy said the bark on the trees is easily damaged when visitors pull or climb on them. The slightest fracture of the bark could let in what he calls “the bad guys,” or fungus, which causes root rot, shortening the life span of the trees. But fungus isn’t the NPS’s only concern.

Crowds walk past the cherry blossoms at the Tidal Basin on April 1. (MANDEL NGAN/AFP/GETTY)

Mike Litterst, a spokesman for NPS, said visitors who wander off the paved sidewalk and onto the roots of the trees can compact the soil, preventing nutrients from getting in.

Visitors stripping petals from the trees, or climbing and breaking branches, are also hazards.

“We had someone last year, a photographer, climbing trees to get the perfect shot of a wedding or engagement portrait,” Litterst said. “They shared [the photo] on Twitter. We had to say, ‘Hey, don’t be that guy.’ ”

[Six spots where you can enjoy the cherry blossoms around D.C. — without big crowds]

Healy said he often sees families placing their young children onto the delicate branches of the trees for photographs.

“If I had young children, I’d probably want to do that myself,” he admitted. Instead, Healy asks families to only take photos in front of the trees.

“We see all of these violations as teachable moments,” Litterst said, adding that even NPS’ junior ranger program and volunteers receive training on educating the public about protecting the trees. NPS also has a full-time tree crew, which works year-round to prune the trees and repair loose bark.

Luckily, Litterst said, the vast majority of visitors are respectful of the cherry blossoms. “They’re helping us take care of them,” he said.