On a recent morning, as the late August sun began to beat down, a few dozen New Yorkers stood in the shade of one of the nearly 500 trees adorning Harlem’s Marcus Garvey Park, worrying a bit about hurting its feelings.
We had already identified the species – bald cypress – thanks to its feathered leaves and “strong pyramidal shape”, measured its trunk’s circumference (17in; 43cm), and noted that its roots appeared normal, its leaves were healthy and its branches had suffered some damage from improper pruning. But now we were tasked with assigning the tree an overall grade – on a scale of “poor” to “excellent” – and no one seemed to want to say.
“Don’t feel like you’re judging the trees,” said Sherlan Greaves, one of the New York City parks department staffers leading the training. “You’re doing this for the health of the tree.”
“Good?” someone offered.
“It’s definitely trying its best,” Greaves conceded. “It could be better. Between good and fair.” (When I checked back later, I saw that the volunteer who was recording our responses had generously gone with “good”.)
This is the New York City Trees Count, a decennial census of the urban forest that makes this concrete jungle livable for 8.5 million people. First undertaken in 1995, the tree census has evolved from a low-tech effort by volunteers with clipboards and measuring tapes to quantify and classify the city’s street trees to 2015’s app-supported production of the Tree Map, an interactive database of the city’s approximately 666,000 street trees.
Taiyo Cannizzo and Sherlan Greaves train volunteers to identify trees at a training event for the New York city Trees Count 2025 in Harlem’s Marcus Garvey Park. Photograph: Julia Carrie Wong/The Guardian
An additional 150,000 landscaped park trees were added to the map from 2017 to 2018, and it is these park trees that will be the focus of volunteer tree counters in 2025. (The city is actually home to more than 7m trees, but those on private property and in Central Park are outside the purview of the parks department, and those on the city’s 6,800 acres of forest are not included in the individual counts.)
This year, the street trees will be counted and categorized by ground-level Lidar scanners mounted on cars – similar to the tech used by autonomous vehicles – which will provide the parks department with detailed scans showing the precise location of trees within the city’s busy streetscapes.
The parks department considered using the Lidar technology to complete the whole project, but the data produced by driving the scanners through the parks “wasn’t great”, Jennifer Greenfeld, the deputy parks commissioner for environment and planning, said in an interview. Perhaps more importantly, she added: “We can’t let people not be part of this.”
Indeed, the tree census has become something of an obsession for some New Yorkers, with certain “supercounter” volunteers logging more than 3,000 trees a piece in the last cycle.
We manage each tree individually and keep records individuallyJennifer Greenfeld, deputy NYC parks commissioner
While none of these esteemed supercounters was present at the training event I attended, the attenders were a diverse group of tree enthusiasts. These included a New York native who was hoping to one day work for the parks department, an archivist and professor of library sciences who had taken a day off work to be there – “We’re all librarians today, we’re all categorizing,” she told me – and a project manager from Greenpoint who proudly displayed her “Citizen Pruner License”, which she had earned after completing an 11-hour training course. (The Trees Count has served as an important entry point for New Yorkers into caring for the city’s green spaces, according to Sam Bishop of Trees New York, the non-profit organization that trains Citizen Pruners to supplement the official seven-year pruning cycle of the parks department.)
That training came in handy once we reached the top of the enormous outcrop of Manhattan schist, the sparkly black bedrock that erupts so exuberantly out of the ground at various points across the island and forms the center of Marcus Garvey Park. We began our survey by updating the record of a decidedly thorny honey locust that had been inaccurately recorded as a thornless in 2015. Insect holes, dangling branches and some strangled roots were duly recorded in the mapping app before we moved on to the next dot on the map: a black cherry we identified thanks to its distinctive “burnt cornflakes” bark.
An ancient and huge tree of heaven – trunk circumference 107in – appeared in excellent health, despite the hundreds if not thousands of spotted lanternflies that clustered on its trunk in patches like an insalubrious arboreal skin rash. A few yards away, all that remained in the spot where the Tree Map said a black cherry should be was a giant stump, a tangle of girdling roots offering a silent explanation of its demise.
Why does the city undertake such a laborious process to count its trees, instead of relying on technology or sampling?
Two volunteers measure the circumference of a tree trunk. Photograph: Julia Carrie Wong/The Guardian
“We think about it every time we do it, like: ‘Why are we doing this?’” said Greenfeld. “We manage each tree individually and keep records individually, so it is really important for us to have a good handle on things individually.”
The census offers a point-in-time picture of the diversity and health of the city’s trees across five boroughs and more than 1,700 parks. The data collected will help inform major initiatives of the parks department, including a plan to increase the city’s canopy cover from its current 22% to 30% by 2035. Trees, like most public goods in New York City, are not evenly distributed, and the census should also aid efforts to mitigate the disproportionate “heat burden” placed on neighborhoods where residents are more likely to be poor or people of color. It also offers a log of the progress the city has already made, including in the important task of increasing the diversity of the trees. The 1995 tree census featured about 70 species of trees; the current map logs 541 species.
“We’ve learned our lessons from many years of different kinds of infestations, whether it was early chestnut blight or Dutch elm disease, that reliance on too few species makes you vulnerable to different kinds of disturbances and storms,” said Greenhold.
Honey locusts remain the most common street tree in Manhattan and the Bronx, while the London plane, with its Pollock-esque bark patterns, dominates Brooklyn and Queens, and the callery pear takes the top spot in Staten Island. The London plane was supposedly “cherished” by the powerful and influential midcentury urban planner Robert Moses, though its reputation for near indestructibility took a hit after Hurricane Sandy revealed it to be sensitive to saltwater; the department now avoids planting them in areas where increased storm surge is predicted.
But the city has been able to expand the variety of its trees by changing its purchasing practices and dealing directly with nurseries. This allows them to acquire trees such as the Kentucky coffeetree – an attractive shade tree that is “very resistant to a lot of urban pressures” but looks like a beleaguered “Charlie Brown tree” in its early years, Greenfeld said – that would otherwise not be commercially viable.
I thought about the resilience that comes from diversity as our group reconvened at the end of the two-hour event, on another day when the US president threatened military action against the residents of cities that he baselessly smears as “blood-soaked” dystopias. Here were New Yorkers of all ages, ethnicities and walks of life, coming together to learn how to do something a bit nerdy and arcane before heading out to do it on our own time, for fun and for the common good.
As we prepared to go our separate ways, a volunteer returned to the group and pulled out her phone to show off the Trees Count version of a celebrity spotting: pictures of an enormous Osage orange tree with a split trunk twisting skyward above a set of Marcus Garvey’s park benches, one of the city’s officially designated “great trees”. Everyone gathered around, ooh-ing and aah-ing.