Trees Literally Save Lives, and the Bigger the Trees the Better

A new study using Friends of Tree (FoT), U.S. Census tract, and Oregon Health Authority data finds that the 49,000 plus street trees the nonprofit FoT planted in Portland between 1990 and 2019 were associated with a reduction in mortality rates of people living nearby. Lead author and U.S. Forest Service researcher Geoffrey H. Donovan and his colleagues found a particularly strong association between nearby trees and drops in cardiovascular and (non-accidental) mortality among males and people over 65, according to ScienceAlert.

Further, the researchers found that the older the trees, the greater their impact in decreasing mortality for the Portland residents living near them. 

Planting new trees is essential to responding to climate change. But according to ScienceAlert, this study finding suggests that “preserving large trees that already exist is even more important for public health.” The study’s researchers are cited as explaining that this is because the larger the tree, the greater its ability to ease air pollution, summer temperatures, and noise, all of which adversely affect human health.

The study is part of a large literature linking nature and tree canopy to public health, but its focus on Portland is especially relevant. The findings reaffirm the value of our main mission—to preserve large-form trees and space to plant new ones across the city, especially in low-income, low-canopy neighborhoods seeing intense development.

Life-saving trees and new housing are not mutually exclusive. Positive examples exist around Portland; sadly, they are the exception rather than the rule. For new affordable housing to be healthy housing, the City must revise its codes and practices to require creative ways of making room for both.

Importantly, the researchers also found that the cost of maintaining street trees is proportionally very small compared to the economic benefits (in lives saved) of planting them. We hope Portland leaders will take note as the City considers how it might find the means of assuming responsibility for street-tree maintenance. Portlanders’ lives are at stake.

Read the study here.