Trees as Climate Resiliency

It’s a big moment for trees.

Volunteers planted a new “Pollinator Pod” near Beale Street Landing this spring. Image courtesy of Memphis River Parks Partnership.⁠

The Inflation Reduction Act — otherwise known as the climate bill, passed by both houses of Congress and signed into law by the President in August — contains $1.5 billion for urban forestry initiatives delivered through the Forest Service, a development that advocates say could benefit neighborhoods for years to come.

Given the extreme weather conditions (searing heat, unprecedented storms) that have prevailed over the summer, the climate bill is a much-needed boost for climate-resilient policy and practice across American communities. Earlier this year, we profiled the work of Professor Vivek Shandas, the founder and director of Sustaining Urban Places Research Lab, an expert on the impact of urban heat islands on cities and the people who live in them. Professor Shandas’ research points to the biggest indicator of localized urban heat: whether a given street or neighborhood has enough tree canopy and greenery to cool the air. His work assessing the cooling impact of tree canopy in Portland, Oregon showed that during heat events, highly treed areas can experience air temperatures of up to 20 degrees lower than areas with few trees and sparse shade.

A big focus for many communities wanting to increase tree canopy is ensuring “tree equity.” With very few exceptions, trees tend to be sparse in communities of color and low-income neighborhoods, and more prominent in wealthier neighborhoods. This phenomenon is tied to decades-long racist policies like redlining and the placement of industrial and heavy commercial facilities in socioeconomically disadvantaged areas. (For information about how your community ranks in tree equity, visit this online tool from nonprofit American Forests.)

When a community’s tree canopy is well-planned, planted and maintained, trees and vegetation can cool, reduce stormwater flows and build resilience for the heat waves and other extreme weather events to come. Here, we profile three cities working at the nexus of public space, climate resilience and urban forests, with lessons for how all communities can manage the resilient, greenery-filled spaces of the future.

Memphis: Assessing existing trees to plan for a more resilient future

Memphis River Parks is the nonprofit organization responsible for the 250 acres of parkland and five distinct park districts along the Mississippi River, adjacent to the city’s downtown. For the past several years, Memphis River Parks, working alongside other public, private and nonprofit organizations, has been reimagining the open fields, clusters of dense canopy, floodplains and steep bluffs that makeup these signature public spaces, working to create welcoming, vibrant public spaces that reconnect Memphians and visitors to the city alike to the unique riparian environment of the mighty Mississippi.

Volunteers of all ages planted trees on Mud Island for Arbor Day. Image courtesy of Memphis River Parks Partnership.⁠

Part of this work includes a recent “Tree Census” of all 250 acres, that will enable the Partnership to understand how many trees, what kind of trees and the age and condition of trees across this landscape, informing future planning and species selections. The goal is to plan (and plant) for future resilience, taking into consideration how trees can improve the park visitor experience, promote the flora and fauna of this important riparian corridor and provide ecosystem services like stormwater management, air pollution reduction and carbon sequestration.

This year’s Arbor Day Tree Planting and Pollinator Planting Party supported creating a nature-rich environment for all. Image courtesy of Memphis River Parks Partnership.⁠

The Census was undertaken using low-cost, free downloadable tools (the team used Epicollect and i-Tree Eco; another tool just developed for assessing ecosystem services from individual trees is i-Tree Design), and while the Memphis River Parks team is still crunching the data of this ambitious project, some lessons learned are already becoming clear. The Memphis River Parks Field Operations team has a snapshot of the current condition of existing trees throughout the system, helping organize pest management, pruning, staking and other tree care based on census data. Maintenance can then be directed at the trees and areas where it is needed in a timely fashion, before anything becomes dire and threatens trees. The Tree Census data gives an overall assessment of all areas’ genetic diversity and age, guiding planting plans far into the future and helping hedge against devastation of any specific species from pests and disease.

The Memphis River Parks team now has a good indication of the ecological benefits of trees today and in the future. Even without additional planting, the current carbon sequestration of the tree canopy across the Partnership’s 250 acres is the equivalent of a car driven almost 19 million miles. The trees remove over 3,400 pounds of pollutants from the air each year and and help manage almost 102,000 cubic feet of stormwater each year — strong arguments for continued planting and maintenance of this valuable urban forest.

Volunteers proud of their newly planted tree after a day of work. Image courtesy of Memphis River Parks Partnership.⁠

Philadelphia: Planning for an urban forest centered on people

For the last several years, the City of Philadelphia has been working on the Philly Tree Plan, an effort to increase the city’s tree canopy and provide “tree equity” in disinvested neighborhoods where there are fewer trees and more intense heat as a result. The soon-to-be released final plan will map out the city’s management of its urban forest for 10 years and lay the groundwork for 30 years of investment, the time it takes many trees to reach maturity. The plan has been and is being developed through the lens of environmental justice, sustainability and community engagement.

The priority map was generated through an overlay of poverty, health and urban heat islands. Images courtesy of Philadelphia Parks & Recreation.

Part of this work included creating a “priority map” where the city will focus early investment, planting, and tree maintenance. Priority areas across the city were identified through an intersectional analysis of poverty, urban heat islands, poor respiratory health, poor mental health and proximity to sources of air pollution.

Another key feature of the Philly Tree Plan’s development has been community engagement, focused most intensively on people living in the priority areas and neighborhoods. Throughout 2021, the city used multiple community engagement tools, including: a citywide survey, neighborhood ambassadors from priority areas, community meetings, a virtual open house and engagement hub and an Instagram challenge for city residents to capture themselves interacting with local trees. By design, almost 60 percent of the feedback came in from priority areas, with the city team wanting to understand not just where to plant trees, but to plant trees in relation to how people used public space. Another focus was listening to people’s fears and objections to maintaining trees on or near where they lived, feedback which was taken into account in the recommendations of the draft plan.

“Our focus in community engagement was not just listening to people once but building relationships with them for the long-term,” says Erica Smith Fichman of the City of Philadelphia’s Parks & Recreation department, which oversees the city’s urban forestry efforts.

The Philly Tree Plan is being finalized and will be released in coming months. Philadelphia Parks & Recreation has received its first funding from the city, and will begin hiring the staff and equipment needed to oversee implementation of the plan in the coming months, with an eye towards a decade or more investment in increasing tree equity and a robust urban forest.

Creating Philly’s Tree Plan included a focus on community engagement, using a range of outreach methods such as neighborhood ambassadors, “walkshops,” community tours and an Instagram challenge. Images courtesy of Philadelphia Parks & Recreation.

Phoenix: Tree equity in the desert

In 2021, Phoenix became one of the first cities in U.S. to announce a goal to achieve “tree equity” by 2030. The announcement, a coalition of local government and non-profit organizations, came with a commitment to reach a goal of 15 percent tree canopy across all neighborhoods in the desert city, with care exercised to choose the right varieties for Phoenix’s low-water needs.

Already one of the nation’s hottest cities, in 2020 Phoenix broke a record for the number of days over 100 degrees (145 days). In neighborhoods with fewer or no trees and extensive pavement, outdoor temperatures can be 10 degrees or more higher than in neighborhoods with more trees, and finding shade while can be a difficult and even impossible task. Neighborhoods without significant tree canopy often contain more people renting housing (unable to plant shade trees) and people who are dependent on transit (who must wait for long periods of time for buses).

Planting in Phoenix to cool neighborhoods and mitigate health impacts of extreme heat. Image courtesy of American Forests.

The tree equity work in Phoenix includes plans for “Cool Corridors” throughout the city to facilitate walking and well-canopied urban parks that provide recreational opportunities and mitigate the urban heat island effect.

The first round of work on tree equity is underway, thanks to fundraising and donations from national nonprofit American Forests. In April, Phoenix residents and local government officials planted 259 trees to complete the city’s first “Cool Corridor” in Cesar Chavez Park in Southwest Phoenix.

“This corridor models the vision for tree equity and will serve students walking to and from nearby schools, public transit riders, and residents in this community,” said Mayor Kate Gallego.

Tree planting of Phoenix’s first “Cool Corridor” in Cesar Chavez Park. Images courtesy of American Forests.

Want to start measuring the impact of your community’s canopy? Or even just the impact that a single tree can have on the environment over a lifetime? Check out the Tree Benefits Analysis Tool, one of several DIY tools developed in partnership with Interface Studio that has been put to use across the Civic Commons Learning Network. The tool, used in conjunction with i-Tree Design, was created to help communities understand the ecological impact of your site’s existing tree canopy and the current and projected ecological impacts of additional tree plantings.

Reimagining the Civic Commons is a collaboration of The JPB Foundation, the John S. and James L. Knight Foundation, The Kresge Foundation, William Penn Foundation, and local partners.