About a dozen people gathered in Dorchester on a recent hot afternoon to go for a walk.

“Last week we did our first ‘tree walk’ here in Codman Square, and we explored west of Washington Street,” Jerel Ferguson of the advocacy group Speak for the Trees said to the group. “Today we're going to explore east of Washington Street. We're going to check out the tree disparities and see, you know, where there are trees and where there are not trees.”

Founded in 2018, Speak for the Trees has been hosting their "tree walks" to talk about the benefits of trees, and to look at where there should be more of them.

It’s an issue of equity. Trees provide a wide range of benefits, from filtering out air pollution to improving mental health — but not everyone gets to feel those benefits. From neighborhood to neighborhood, or even street to street, there are often wide disparities in the number of trees, which can have a broad impact on the overall health of a community.

On a local, state and national level, though, governments and nonprofits are investing to make up the gap as the concept of “tree equity” is beginning to take root.

WATCH: ‘Trees in Boston: Who gets more and why it matters’

“There is a lack of trees in most of the communities of color,” said Marilyn Forman of the Codman Square Neighborhood Development Corporation as she helped lead the tree walk. “So, we have programs where we end up actually distributing air conditioners because it's so hot, because everyone's on this heat island, you know. A lot of concrete.”

More than 42% of West Roxbury, for example, is covered by tree canopy — even going above the 40% recommended for suburban settings like the Boston area. In East Boston, it's less than 8%, well below the lesser threshold of 20% recommended for urban settings. The city’s tree inequities are highlighted in a new series of interactive maps published by Speak for the Trees.

Trees help combat the urban heat island effect, where cities — or parts of cities — experience much higher temperatures than nearby suburban or rural areas. A series of interactive maps from Speak for the Trees shows the disparities in Boston’s tree canopy.

Design by Chad Fisher, Speak for the Trees; data source: City of Boston, Canopy Change Assessment: 2019 Tree Canopy Polygons.

Trees do a lot more than just provide shade.

“The water that comes out of the tree's leaf as it evaporates, cools down whole neighborhoods,” said Speak for the Trees’ executive director David Meshoulam. “You also have air pollutants that are being absorbed. So you're reducing asthma. They absorb stormwater. So, basements aren't flooding. People tend to be more stressed when they're not around trees, so trees calm the nerves. They reduce blood pressure.”

More trees has an economic upside, too, Meshoulam added: it helps residents keep costs down since cooler temperatures mean less need for air conditioning.

“This is an opportunity,” Meshoulam said as he looked down a block of Aspinwall Road in Dorchester with barely a tree in sight. “This is what we call a tree desert. And in a street like this, you'll have summer temperatures anywhere from 5 to 10 degrees hotter in the day. And these neighborhoods actually don't cool down as much at night because the asphalt has absorbed all that sunlight during the day.”

In urban areas, a lack of trees is often related to racial inequities, Meshoulam said. Researchers have reached that conclusion time and time again across the United States when studying heat in cities, finding that redlined areas are consistently several degrees hotter.

“There’s a correlation between tree canopy coverage ... and historic and continued racist practices like redlining, like disinvestment, and white flight,” Meshoulam said.

Dorchester resident Darlene Harrison said taking part in these community walks has made her more aware of the value of trees.

“I was kind of disappointed because, in my complex, they took all the trees down, most of the trees in the front of the house,” Harrison said. “And I'm asking them, ‘Can we have our trees back?’”

Advocates for trees say there is movement to tackle the issue.

“This is what we call a tree desert. And in a street like this, you’ll have summer temperatures anywhere from 5 to 10 degrees hotter in the day.”
David Meshoulam, executive director of Speak for the Trees, looking down Aspinwall Road in Dorchester

In Boston, the city published a long-term plan last year for expanding its tree canopy. To accompany its plan, the city put out neighborhood-level maps that lay out which areas have the least tree canopy, like Charlestown (11%), Central Boston (9%), South Boston (8%) and East Boston. (Dorchester sits at 22%, still below the city’s average of 27%.) The city hired Todd Mistor to be its first director of urban forestry.

“From our urban forest plan, we have a set of goals that we came up with,” Mistor told GBH News. “And one of those goals is, of course, to have equity first in whatever we do, to try and focus on an equity approach. But another component of that, that dovetails right into it, is that it’s a community-led process. So, we really need to be in contact and engaged with the community.”

Boston planted nearly 1,400 trees this spring, according to a detailed online inventory the city keeps. Residents can call 311 to request that the city plant a tree — but, according to Mistor, it takes a long time.

“We look at those [requests],” he said. “We have a lot of them. And part of building capacity within the division is to make sure that we can get through those quicker. It's a long process. There's a lot of requests that have built up there. But again, as we're building capacity, we want to have a better response time.”

Boston is also partnering with local community groups to plant trees on private property, and to educate residents how to care for trees. That partnership, called The Boston Tree Alliance, is being headed up by Mass Audubon.

“Only 40% of the land within the city is under city jurisdiction in one way or another,” Mistor said. “And we currently don’t have any authority for the trees on private property. So, if we really want to increase canopy coverage, we can’t just focus on city-owned property.”

In addition to planting trees, Stacey Beuttell — who leads Mass Audubon’s Nature in the City program — said the alliance is focused on educating residents about the care and maintenance of existing trees.

“It’s really critical that the alliance build an awareness around the importance of tree care to those private landowners and also act as a resource for them about what it means to take care of trees,” Beuttell said.

She said the Boston Tree Alliance aims to plant 600 trees on private property in the next three years.

On the state level, lawmakers are considering a bill that would encourage cities and towns with low levels of tree cover to create reforestation plans and help them buy trees. It would build off of a yearslong program that has already planted thousands of trees in the commonwealth’s “Gateway Cities,” such as Lynn, Fall River and New Bedford, that suffer from urban heat islands.

“A lot of communities have funds for trees, but they tend to be very small and they don’t allow a lot of purchasing,” said state Rep. Jenny Armini, one of the lawmakers who introduced the bill. “So, this is something that I think requires a bigger boost.”

Armini said she’s optimistic about the bill’s prospects in the Legislature and about the impact it could have.

“Trees have become an important part of the climate change conversation,” she said. “And so communities are looking to actually increase their canopy as a result of that. And this would be a terrific tool for them.”

Nationally, the Biden administration announced in April that it was investing $1.5 billion in building urban forests, through the Inflation Reduction Act — including $1 billion that will be distributed through grants.

Joel Pannell, who works on urban forest policy with the national nonprofit American Forests, said that’s a huge increase from the roughly $35 million that’s typically devoted to the effort each year.

“The hope is that we’re going to truly prioritize getting this funding where it’s needed most, sort of turning that funnel upside down where those who typically had access to the least now are first in line with access to these unprecedented funds,” Pannell said.

Boston has applied for nearly $11.5 million in those federal grants. Pannell says the grant awards are expected to be announced sometime in the next two months.

American Forests offers interactive maps that compare “tree equity scores” for cities across the country, with Boston scoring a respectable 92 overall. But the neighborhood disparities highlighted by Speak for the Trees become clear when users zoom in.

“Boston as a city may be doing fairly well, but then you can still look within that and see ... you have pockets and neighborhoods [where] scores are in the 20s, 30s or 40s, you know,” Pannell said. “The tool is designed to say, ‘Here’s where we really need to be prioritizing our funding investment. Here’s where people are most vulnerable to extreme heat, to flooding, to air pollution’ — to things like that.”

For David Meshoulam of Speak for the Trees, a burst of government support is encouraging. But, he added, really growing the tree canopy — and maintaining it — will take more than that.

“It can’t be just the city. It can’t be just the state,” Meshoulam said. “It has to be everyone literally rolling up their sleeves, getting their hands dirty. Advocating for trees, advocating for their care, advocating for their preservation.”