New York will plant thousands of trees using new tech to maximize foliage impact | New York

Aew York City is set to get a lot more trees. Last month, the city council passed a measure asking for that 30% canopy cover by 2035, from its current coverage of 22%; a recent tree census found there is enough room in the city to plant an additional 250,000 new trees.

More trees, with all their cooling benefits, are a clear win for the environmental justice movement as cities around the world try to adapt to warmer temperatures caused by the climate crisis. But where those trees should go – and what kind of trees to plant – is not so simple.

“It’s about not just planting more trees, but the right tree in the right place,” said Alexander Kobald, a researcher at Cornell University. “It really focuses on what the place is asking for and to make sure the people [who live near the trees] feel heard.”

Kobald led the design of Boomfolio NYC, a 3D mapping tool that can help city planners solve this problem. Released in August, Tree Folio NYC used lidar scans to present a “leaf level” visualization for each of the city 7m trees . By focusing on individual trees rather than the city’s total tree canopy, Kobald said, researchers can learn more about how trees contribute to the overall shade of specific areas and then better direct resources to those areas.

“Unlike industry standard tools that tend to look at overall canopy cover … this research seeks to understand the total impact of trees based on their individual contributions,” Kobald said.

Expanding the city’s tree canopy has year-round benefits. Exposure to trees was shown to strengthen immunity, lower stress and blood pressure, improve mood, sharpen focus and increase energy levels. Children who live in areas with more street trees are less likely to do so suffer from asthma.

But communities of color in the US have, on average, 33% less tree felling than majority-white areas, according to American Forests’ Tree Equity Score. This lack of trees contributes to the urban heat island effect, where buildings, roads and other built infrastructure absorb heat, making those neighborhoods significantly warmer than nearby greener neighborhoods. Low-income neighborhoods and communities of color are more likely to be located in urban heat islands, a legacy of segregation and racist realignment practices.

As cities experience longer and more severe heat waves, these differences can become deadly. Black New Yorkers are about twice as likely than white residents to die from heat exposure, according to 2022 city data.

Historic, urban trees are planted in uniform rows, to prioritize aesthetics and economic development on maximizing their climate benefits. Kobald argues that more strategic placement of trees can improve their climate impact and ensure they are distributed more equitably.

“I think the relationship between tree shade and the local context [illustrates] the need to give streets more design attention,” Kobald said.

Kobald points to other improvements that, along with tree placement, can create safer streets for all residents: allocating more pedestrian space to sunnier sides of streets where desirable, protecting bike lanes and investing in overall pedestrian comfort.

“I think what Tree Folio does is really helpful when you’re thinking about placement, where to get the most shade and how to reduce heat,” says Rachel Comte, owner of Urban Canopy Works, a collective of arborists and planners that consults on urban forestry in cities across the US.

This kind of strategic thinking about how and where to plant trees can be beneficial in dense urban environments such as New York City, especially in areas that need the most shade and cooling.

“The trends are historic and persistent; there is less tree cutting in areas that have more social vulnerability in terms of the communities that live there,” says Mike Treglia, chief scientist for the cities team at The Nature Conservancy in New York.

In 2021, The Nature Conservancy released a comprehensive report, The state of the urban forest, what it found the South Bronx, a historically low-income area with some of the highest asthma rates in the country, saw notable increases in canopy cover from 2010 to 2017. However, its particularly dense urban landscape creates restrictions on how much new tree canopy can grow there.

“A lot of this is driven by the built environment,” Treglia said. He points to streetscapes, parks and open street initiatives as answers to how more space can be created for street trees.

New York City also passed new urban forestry laws which calls for the creation of an urban forest plan, to be updated every 10 years and monitored every five years by lidar data.

But the new laws do not allocate further city funding, and urban forestry has historically struggled to maintain adequate funding in New York City.

“Often funding for trees and tree-related things is cut first and kind of at a greater rate,” said Emily Maxwell, cities team director at The Nature Conservancy, which advocated for the law.

In September, the mayor of New York, Eric Adams, all city agencies ordered to cut spending by 5% by next spring.

“With the new cuts, the jury is still out on what the impact will be on the urban forest,” Maxwell said. “Advocates are very concerned, especially about some of the newer funding that is in place.”

One of the more ambitious elements of the new plan is its emphasis on maintenance so that trees make it to maturity.

“Consider the difference between a 3-inch oak and a 30-inch oak,” said Comte, of Urban Canopy Works. “That 30in oak provided intercepts 70 times more air pollution than the 3in oak,” said Comte. “The mature trees do the lion’s share of the work. So we really want trees that will make it to maturity.”

In urban environments, this involves being creative. The average lifespan of a street tree, exposed to root-eroding elements such as pet urine and road salt, is 19-28 yearscompared to the 300-400 years which is typical for a tree in other conditions. To increase trees’ chances of reaching maturity, city planners must plant a diverse variety of them to ward off disease, favor climate-adaptive species, maintain healthy soil conditions, and allocate enough space—above and below ground—for the trees to grow. growth. This also means monitoring tree health in real time.

That’s where Tree Folio comes in, Kobald said.

“Our model is able to measure canopy cover using newer lidar data than existing canopy cover maps and measures the size and volume of individual canopies, making it easier to see where healthy trees are located and where existing canopies are missing,” Kobald said.

And those abilities aren’t limited to New York. Kobald said the tools developed in Tree Folio’s map can be used for any city with lidar coverage, which includes most urban areas in the US.