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Town proposes mini-forest to combat urban heat island

A rendering of the proposed mini-forest in Brookline
A rendering of the proposed mini-forest in a Brookline Avenue park. Photo courtesy of Brookline DPW
June 26, 2023

As it seeks ways to fight the climate crisis, Brookline is looking at creating a mini-forest, hundreds of densely planted trees and shrubs that can become self-sufficient within three years, at a playground on Brookline Avenue.

Brookline’s Urban Forest Climate Resiliency Master Plan, which sets goals to increase the tree canopy in town, identified North Brookline as a priority planting area. The neighborhood is part of an urban heat island. Its heat-absorbing buildings and pavement make it three to five degrees warmer than the more suburban South Brookline. That effect could be mitigated by an increase in the tree canopy, the town says.

North Brookline’s densely populated streets and lack of open green spaces present a challenge, Alexandra Vecchio, Brookline’s director of parks and open space, said in an interview.

The Department of Public Works already plants more than 300 trees a year in front yards, parks and school grounds across town, Vecchio said, and has been looking for new initiatives to support North Brookline’s canopy.

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“Being in an urban environment, it is not always easy to establish and grow new trees,” Vecchio said. “So [we’re] looking for other ways that we can still grow our canopy in addition to our typical tree planting program. That’s where this mini-forests concept came into the equation.”

The Brookline Park and Recreation Commission, which held a hearing on the mini-forest proposal last week, is expected to vote on it next month.

Mini-forests, or Miyawaki forests, are densely planted trees and shrubs used in urban settings to create their own ecosystems and counteract some of the negative health and financial effects that heat islands can cause. Over 300 seedlings are planted, then irrigated and weeded for three years. After that infancy period, the mini-forests are self-sufficient.

The town picked the Brookline Avenue Playground on the corner of Brookline and Aspinwall Avenues for what it hopes will be the first of many mini-forests. Located between the playground and the back of the baseball field, the mini-forest would fill a rectangular space of about 1100 square feet. A fence around the mini-forest would keep out dogs and people.

While it was difficult to find suitable open space in North Brookline, the high visibility of the park made it a prime location, Vecchio said. In addition to combatting the urban heat island effect, mini-forests also engage and educate the community by reconnecting residents with the natural world and native plants.

At last week’s hearing, the proposal generated only favorable comments from the commissioners and attendees, including local professors and scientists. If the proposal passes, the forest is set to be planted in October.

A mini-forest in Danehy Park in Cambridge, right after being planted. Photo courtesy of Paula Phipps

Success in other communities

Mini-forests aren’t new to the Boston area. In Cambridge, the nonprofit Biodiversity for a Livable Climate has planted mini-forests at Danehy Park and Greene-Rose Park.

“They help cooling in an immediate area,” said Paula Phipps, the organization’s executive director. “They help clean the air of toxic particles. They make the ground more porous, so that the water sinks into the soil and there’s less flooding.”

Both mini-forests are less than three years old, but the results so far have been positive. The survival rate of the plants is extremely high and the community is engaging with the forests. One visitor called them a “little piece of heaven,” Phipps said.

“Occasionally, a tree might need to be replanted, but, my goodness, at our Danehy Park forest, I certainly don’t see any places that need anything,” she said of the mini-forest planted almost two years ago. “It is very dense.”

Volunteer-led process

Brookline’s mini-forest project will rely on community support, said Vecchio.

“Projects like these are really exciting, but they do require buy-in and support and in this case, some real sweat equity from the community,” she said.

The local chapter of Mothers Out Front would provide volunteers for the planting in October and for the next three years of upkeep. Brookline’s chapter of the nonprofit has three teams – a fossil fuel free team, a zero waste team and a tree team.

The Brookline Avenue park is located in a town-designated environmental justice neighborhood. It is in Precinct 4, which is one of two BIPOC-majority precincts in Brookline and which includes a public housing development.

That was one of the reasons Mothers Out Front urged selection of the site, said Olivia Fischer Fox, who leads the organization’s tree team.

The goal is “to start with those that are faced with greater challenges and bring them the joy of watching this grow and having a cool place to sit while they watch their children and teach the children, and also to have the children participate and get to watch this grow in their lifetime,” Fischer Fox said.

The planting would most likely take place over one or two days in October, and Mothers Out Front is looking for volunteers to help out.

Gina Crandell, a landscape architect and the mini-forest project leader with Mothers Out Front, said the plants include blueberry, elderberry and witch hazel shrubs as well as hickory, white oak and red oak trees.

“Sometimes we think about saving nature, but it really is the reverse. We’re really trying to save ourselves,” Crandell said. “Biodiversity is just crucial to our survival.”