Growing Awareness: Urban Trees are Essential Infrastructure
Author: Sarah Staub
The Urban Tree Crisis
Currently, 84 percent of Americans live in urban areas, a core principle of urban planning that focuses growth in developed areas to preserve natural landscapes. This approach aligns with the Growth Management Act, which legally mandates sustainable development to safeguard undeveloped land.
As the climate changes, its impacts are increasingly evident. One example is excessive heat from sudden summer surges known as "heat domes," which can drastically impact public health, especially in low-income communities, among people of color, and older adults, who are more vulnerable.
A significant climate-related challenge is the loss of urban trees. In the U.S. alone, urban areas lose 36 million trees annually due to natural disasters and disease. The U.S. Department of Agriculture notes that urban trees typically live between 19 and 28 years, as they face pollution, poor soil quality, limited space for root growth, and pressure from pests and disease.
This loss comes at a high cost to urban residents, as illustrated by Tacoma, Washington. Tacoma has the lowest tree canopy in the Puget Sound region, with just 20 percent of the city shaded by trees. According to "Tacoma Urban Forestry: The Intersection of Trees, Equity, and Human Health," areas lacking tree coverage often coincide with historically marginalized communities. “Tacoma’s challenges stem from a long history of racism, including redlining policies that dictated where Black, Indigenous, People of Color, and immigrant communities were allowed to live.” Geographic Information Systems (GIS) mapping shows that redlined neighborhoods were often excluded from green infrastructure investments, resulting in higher impervious surface areas—19 percent more in low-opportunity neighborhoods—which intensifies the urban heat island effect.
Improving Quality of Life
Urban trees provide more than aesthetic value; they contribute significantly to quality of life by reducing noise pollution, creating calming environments, and lowering blood pressure and stress. Additionally, they improve air quality by removing 710,000 tons of air pollutants annually in the U.S. and block up to 96 percent of harmful UV radiation.
Urban tree canopies also reduce ambient temperatures by 2–9 degrees Fahrenheit, a crucial benefit during extreme heat events, particularly for underserved and historically marginalized neighborhoods.
Moreover, trees enhance public safety and property values. A 2010 University of Washington study found that increased tree canopy correlates with decreased crime rates. Public housing areas with more trees report lower rates of vandalism, littering, and domestic violence. Buildings with more vegetation have up to 52 percent fewer property crimes and 56 percent fewer violent crimes.
Triple Bottom Line Impact: Economic, Social, and Environmental
What can be done to protect and enhance urban forests to combat climate change and improve neighborhood livability? Advocacy for funding, ordinances, and policies is essential. Recognizing this, many cities, including Tacoma, have implemented tree ordinances to address climate adaptation and equitable tree distribution. Tacoma’s municipal code (Title 13) outlines five key objectives for urban forestry:
· Plant more trees
· Enhance plant selections and planting locations
· Improve urban forest health
· Provide incentives and flexibility
· Ensure an understandable and predictable approach
While preserving mature trees is important, planting new trees is equally crucial. Tacoma is aiming for a 30 percent tree canopy by 2030 by protecting existing trees and strategically adding new ones. Local groups like Tacoma’s Urban Forest Friends (TUFF) provide residents with tree planting guidance, while the Tacoma Tree Foundation and Grit City Trees program offer free or low-cost trees.
Investing in a Healthy Future
Federal, state, and local programs are investing in urban forestry. In 2022, the Urban and Community Forestry (U&CF) program received $1.5 billion from the Inflation Reduction Act for urban tree planting and maintenance. The Pacific Northwest was awarded over $100 million, with priority funding for disadvantaged communities. Additionally, the Arbor Day Foundation has pledged to plant 500 million trees by 2027.
Living Example: Hilltop Housing
In Tacoma’s Hilltop neighborhood, the Tacoma Housing Authority’s Hilltop Housing project aims to revitalize the area with two mixed-use buildings providing 231 affordable housing units. AHBL’s landscape architecture team collaborated with the design team to incorporate new tree code requirements and meet the community's needs for greenspace, recreation, and health. The project includes courtyards with existing street trees and new plantings to create a welcoming environment.
At AHBL, we are proud to contribute to our communities through innovative planning, design, and engineering that enhance urban landscapes and improve lives.
Get Involved in Tacoma Trees
There are many ways to support urban forests. You can become a tree steward, volunteer in your community, and participate in annual programs like Branch Out and Green Tacoma Day to preserve, plant, and care for trees.
Resources
· Tacoma_UrbanTreeCanopyReport_2018.PDF 2
· Flood impacts - Washington State Department of Ecology
· Urban and Community Forestry Program | US Forest Service (usda.gov) 3
· Tree Planting Nonprofit | Arbor Day Foundation
· City Forest Credits | Local Carbon Credits & Impact Certification
· Using Trees and Vegetation to Reduce Heat Islands | US EPA
· Canopy Cover - City of Tacoma
· Tacoma Community Forestry (arcgis.com)