Giving city trees a fighting chance

Scientists publish guide on urban tree planting

Hilary Clark

Pacific Southwest Research Station

September 4, 2024

A group of mariachi musicians playing on a neighborhood street behind a table with cakes on it, while residents of the neighborhood watch and enjoy the music. — Mariachis play during a tree planting event in the Boyle Heights neighborhood of Los Angeles. Forest Service scientists advocate that tree planting events include a broad spectrum of community involvement. (*Photo courtesy of City Plants*)

From car doors banging against trees to construction projects that damage roots, urban trees have it rough.

“City trees are some of the hardest working trees there are. They must live in a built environment with thousands of people,” Erika Svendsen, social scientist with the Forest Service’s Northern Research Station said.

In fact, Forest Service research showed that half the trees planted in an urban environment live just 13 to 18 years, with more than 30% dead within five years.

Those sobering tree mortality statistics inspired Svendsen and a team of scientists and partners to collaborate on a research article to give city trees a fighting chance. The other scientists include colleagues Lindsay Campbell, a social scientist with the Northern Research Station and Lara Roman, a research ecologist with the Pacific Southwest Research Station. Theo Eisenman from the University of Massachusetts Amherst and Johan Östberg with Nature Based Solutions Institute also served on the team.

Beyond the Golden Shovel offers practical advice to city planners, landscape architects, urban foresters and others when planning tree planting initiatives.

A group of people in a park stand around a large table with maps of the park laid out in front of them. — A public engagement neighborhood meeting with Onondaga Earth Corps in Syracuse, New York, drew together planners and members of the community. (*Photo courtesy of Syracuse Department of Parks, Recreation & Youth Programs*)

Promoting Sustainable Cities

“In our article, we suggest that tree planting itself is not the goal. Rather, tree planting is a means towards the greater goal of creating more livable, equitable and sustainable cities,” said Roman.

When trees and urban forests thrive, they help make local cities more sustainable. These hard-working plants store carbon and help reduce air pollution and energy use, giving back to their communities. According to Forest Service research, those environmental benefits contribute $18 billion to the economy every year.

Recognizing what urban forests do for us, the U.S. Department of Agriculture has invested in them. The agency has funded $1 billion for nearly 400 projects
to expand access to trees and green spaces in communities throughout the country.

The research team is excited about this unprecedented influx of federal funding for tree planting initiatives and urban forest management. But they caution that urban trees need a lifetime of investment to survive to adulthood and provide full environmental benefits.

“It takes roughly three decades for the carbon sequestration of a new urban tree to offset carbon emissions from vehicles and tree care equipment used during nursery production, planting, and pruning,” the authors wrote in Beyond the Golden Shovel.

With over 30% of these trees dying within five years, many are not living that long.

Beyond the environmental and emotional loss, a tree’s death is expensive. In the U.S., city officials typically spend $500 to $3,500 planting just one tree. If that tree dies, it contributes to what is labeled greenwasting, where projects touted as environmentally meaningful fail. Greenwasting is not only costly but can erode a community’s trust in local government.

Three images side-by-side. Left image has people standing around a table in a library, planning locations for tree plantings. Text on the image reads: “Pre-Planting” The middle image shows a group of people in visibility vests planting trees in a neighborhood. Text on the image reads “Installation” The right image has a group of people in visibility vests examining a young tree that has been planted. Text on the image reads “Post-Planting”. — Examples of resource allocation across the three phases of an urban tree planting initiative. (*Left image courtesy of City Plants in Los Angeles. Center image courtesy of Canopy in Palo Alto, California. Right image in Worcester, Massachusetts Photo courtesy of Lara A. Roman*)

Planting Trees Takes a Village

On the flip side, successful tree planting initiatives can build community support. Like roads, sidewalks and other gray infrastructure, or as pipes, culverts, gutters and ditches that require ongoing maintenance, trees and other green infrastructure need adequate care and resources throughout their lives. Successful tree planting initiatives, the researchers believe, require a holistic approach and engaging arborists, nursery industry staff, and other tree professionals. They recommend city planners, municipal leaders, and others who support tree planting initiatives consider the type of tree, its location, and how it will fare with climate change.

Two young people in visibility vests examine trees at the corner of two residential streets in a neighborhood. — Young citizen scientists checking young street trees in Harrisburg, Pennsylvania, as part of a monitoring project with the Forest Service and the Pennsylvania Department of Conservation and Natural Resources. (*USDA Forest Service photo by Lara Roman*)

“Our paper channels the best practices and recommendations we have heard from amazing urban forestry and arboriculture collaborators,” Roman said.

Beyond weighing environmental factors and constraints of planting trees, the researchers emphasize that community involvement is key. The benefits of trees in providing shade and beautifying urban landscapes are well-known, but not everyone is a fan of trees. Some are allergic to certain species. Others view them as potential hazards that could knock down powerlines or fall into buildings. Getting people to connect to and care about trees is vital for the survival of urban trees.

“When a tree falls in an urban forest, do people care? The real shame is not when a stewardship program tries something new and it fails, but when a tree dies and no one cares,” Svendsen said.

Even when residents do care about trees, however, equity issues come into play. Some residents live in underserved neighborhoods with little to no greenspace and few trees. Planting trees in these areas seems like a simple solution. But it’s not that easy.

When Roman and colleagues at Philadelphia’s Temple University spoke to residents and community leaders about barriers to their participation in tree planting, many expressed concerns about the expense of caring for a tree throughout its life. Residents in other cities have voiced similar concerns. That’s why Roman and fellow researchers believe it takes a village to properly care for a tree.

“Over a city tree’s lifecycle, it may be cared for by non-profit staff and their volunteers, residents, municipal employees of parks or public works departments, utility companies, private tree care firms, and more,” Roman said.

Greening Cities

Modeling this village approach, some cities are taking a stand for trees in their neighborhoods. The New York City parks department completed an ambitious campaign to plant and care for 1 million trees. In Philadelphia, the city released an urban forest strategic plan focused on environmental justice. In Los Angeles, an urban forestry program is creating more space for trees in low canopy neighborhoods and sponsoring paid Tree Ambassadors.

Social scientist Francisco Escobedo and other Forest Service researchers are evaluating these model programs, which can promote civic pride and a sense of community.

“Successful tree planting initiatives can create a network of support for trees that comes from caring for another living thing. And that benefits us all,” Svendsen said.