The Miyawaki forest at Danehy Park got an intervention Friday – something that wasn’t supposed to be necessary at an innovative patch of greenery planted four years ago to be “self-sustaining.”
Workers came to the park in North Cambridge and removed a dozen trees, planted 20, cut back sod and weeds around the forest perimeter and put in place a mulch ring to reduce weed infiltration and competition, said Alexandra Ionescu of Biodiversity for a Livable Climate, in an emailed reply to media and resident concerns. The nonprofit, also called Bio4climate, partnered with the city of Cambridge and the Sugi Project, a San Francisco forestry nonprofit, in a Sept. 25, 2021, planting in Danehy that drew more than 100 volunteers.
The reason for all the work: sumac, said Ionescu and Cambridge spokesperson Jeremy Warnick.
“There was a concern that sumac was beginning to overwhelm the forest. If the sumac continued to grow, it would threaten the health of the forest,” Warnick said Friday.
The work and how it was done shocked Joni Seager, a Cambridge geographer, climate specialist and ecologist at Bentley University in Waltham. She was one of the volunteers who helped plant the forest, and said she visits it almost weekly.
“The implantation of new trees is entirely against the Miyawaki principles. Twenty of them is beyond belief,” Seager said. “What was last week a robust – even if erratic – tree-based ecosystem is now being treated as though it’s a copse of park trees to be curated.”
In an emailed reply to Ionescu, Seager called the forest “wrecked,” thinned out to “an alarming extent” that leaves soil exposed and animals lacking in plant cover. During a visit as the work was being done Friday, she said she found no Miyawaki specialist present to oversee the gardening, and workers who lacked “any clue that this was a ’special’ forest.”
Seager further said in her email “There’s no more experiment. You’ve reduced a once-visionary effort to a problem of ’park tree management.’” What’s next? Herbicides to kill weeds?”
Seager sent her email to Biodiversity for a Livable Climate after business hours, and the organization had not responded by publication time. But a public announcement was promised soon from the city, and Ionescu said her group plans to publish a blog post that explains how this work aligns with the broader ecological principles of the Miyawaki method.
What went wrong
The forest at Danehy Park – the first in the Northeast, and now one of three in Cambridge – was planted with 1,400 trees and 32 native species in a circle of just 4,310 square feet. The intense biodiversity is supposed to give Miyawaki trees a survival rate of between 90 percent and 95 percent and even accelerate their growth.
The forest in Danehy Park has worked despite a couple of things going awry: The first, Bio4climate realized recently, was that during the original plant delivery, “a few understory species” were substituted with sumac, a fast-growing member of the cashew family. “We waited to see whether the slower-growing canopy and understory species could compete. Over time, it became clear that they were being suppressed,” Ionescu said.
In addition, Cambridge has had a series of droughts, including in 2022, last year and twice this year. During these periods, “the native sumac species performed extremely well – so well, in fact, that they began to dominate the site,” Ionescu said. “In an effort to restore a multilayered forest structure that the Miyawaki method requires and maintain species diversity, the intervention became necessary.”
“We see this forest as a living classroom – one that continues to teach us about how native species interact, compete and cooperate under changing conditions,” Ionescu said. “We understand how unsettling it can be to see interventions in a young forest that was planted to grow naturally. These actions were carefully considered and carried out to support the long-term goal of creating a resilient, multilayered, biodiverse miniforest community that can thrive for generations to come.”
Earlier interventions
The advance of the sumac was being watched by Sugi too. A “forest maker” at the organization named Ethan Bryson assessed progress at the Danehy Park forest in November and found “some species are thriving while others have been shaded out.” An abundance of sumac “may have accelerated this.”
“Despite these challenges, the emergence of oak beneath the sumac indicates that the forest is progressing toward more complex layers of growth,” Bryson said. Yet Sugi also performed interventions: It added a liquid compost stimulator last year, and removed invasive species such as goldenrod and ground ivy.
That wasn’t exactly how the concept was described in 2021, when Boston.com promoted the forest as “completely self-sustaining.” The New York Times was more measured in its reporting from North Cambridge in 2023, saying the forests needed “no weeding or watering after the first three years.” A Mongabay article in 2023 noted that the forests may need to be modified in some environments.
A stronger
Please consider making a financial contribution to maintain, expand and improve Cambridge Day.
We are now a 501(c)3 nonprofit and all donations are tax deductible.
Please consider a recurring contribution.
Probably Tree of Heaven, not Sumac. This is the tree that is taking over Route 2, Alewife, the region. I really hope they work on getting rid of it.
I always thought it was weird that they planted sumac. Sumac is a pest!
Is it possible that the goldenrod were subspecies? Golden rod is native and there are many subspecies, knowing about the planners it would be unfortunate if rare native plant species of goldenrod like wrinkle leafed goldenrod or seaside goldenrod were removed. This was such an important experiment towards livability and trying to manage soil bioremediation for North Cambridge and addressing long term watershed issues and for density for new potential neighbors. This could likely be a major set back housing building constraints potentially if Miawaki space is lost, and that would be sad for the experiment.
Livability so often depends on environment and balancing development and long term sustainability. This will be a tangible issue to address with urgency in helping balance urban living with the environment we depend on for clean water, clean air, living soil, and remediation for waste management at least.
The Tree of Heaven (aka Sumac) is a preferred plant host for the spotted lanternfly. See Michigan State University Bulletin E3486, “A Tale of Two Invaders: Tree of Heaven and Spotted Lanternfly” (October 2, 2023).