New York City’s security companies are embracing a new tool in their mission to protect private property: public trees.

In recent months, security contractors have quietly drilled electronic “tokens” into the trunks of city street trees. Guards scan the trackers with their phones, providing real-time data on the status of their patrols.

Security providers touted the devices as an effective accountability tool — a way to assure clients they are keeping a close eye on their assets. But as the arboreal checkpoints gain popularity, both tree lovers and surveillance skeptics are raising concerns.

“They’re totally wounding the tree,” said Justin Rawson, an arborist in Brooklyn. “Even if they can withstand it, no one should be doing this to city trees.”

A spokesperson for the city’s parks department confirmed they were aware of the trackers, which violate the city’s law against defacing trees. But that hasn’t stopped private companies, some of whom are contracted by the city, from taking advantage of the urban forestry. And it appears unlikely the city will issue violations, according to the parks department.

“Sometimes in Manhattan, there’s no place to put anything,” said Evans Imafidon, the CEO of Kings Security Service, a Bronx-based contractor that provides security to both luxury apartments and city buildings.

The firm has installed half-dollar-sized badges on at least 10 trees – gingkos, honey locusts, and pin oaks among them – that line the streets surrounding a middle school construction site in Alphabet City.

“It’s good exercise,” said the site’s guard, Joseph Taylor, as he stepped over piles of trash and rat-infested tree pits to reach the checkpoints. His main responsibilities, he said, were keeping trespassers out of the school and deterring homeless people from lying on the sidewalks.

Roughly a mile west, the Bowery Residents’ Committee, a homeless services provider, has taken a similar approach to sidewalk security. Over the summer, trees on the four blocks surrounding the building received white buttons, according to employees who said they are expected to scan them on nightly patrols.

Muzzy Rosenblatt, the executive director of the BRC, said the security posts were part of the shelter’s “good neighbor program,” which aims to assure nearby residents that the provider is keeping a close watch over the street. He said it was a mistake to use the surface of trees for the program.

“We've been doing this for years, this is just the use of a new technology,” he said. “We're there encouraging positive behavior, discouraging negative behavior, looking out for the welfare of our clients and the community.”

Jeremiah Moss, a writer and local resident who spotted the Bowery badges last month, said he felt uneasy about the surveillance system.

“It’s the creep of privatization and policing, a sense of entitlement to encroach on public space,” he said. “Those buttons aren’t just little buttons, they’re another link in the chain.”

Following a post on Instagram and Gothamist’s inquiries, at least one of the devices was removed from the Bowery, according to Crystal Howard, a spokesperson for the parks department. She said it did not appear the tree suffered any significant damage.

Indeed, many of New York’s street tree species were specifically selected for their resilience to foreign substances, such as urine, according to arborist Alec Baxt.

The trackers that remain will eventually be subsumed by their hosts as part of a complex sealing process that protects the rest of the tree from further decay.

“It’s one more human invention that will be swallowed by time and nature,” Baxt said. “Then what happens to worker productivity?”

This story has been updated with additional information.

Correction: A previous version of this story misspelled Justin Rawson's name.