Plant a tree and save a life? The value of planting more trees in urban areas
| Authors: | Andrea Watts, Geoffrey Donovan, Demetrios Gatziolis |
| Year: | 2024 |
| Type: | Science Findings |
| Station: | Pacific Northwest Research Station |
| Source: | Science Findings 263. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 6 p. |
Abstract
Exposure to urban trees is associated with improved public health outcomes, including healthier infant birth weights, fewer symptoms of attention-deficit hyperactivity disorder, and decreased cardiovascular mortality. Conversely, tree loss is linked to increased rates of cardiovascular disease and higher mortality. Could this mean that trees save lives?
Using 30 years of tree planting data generated by Friends of Trees, a nonprofit organization that has planted trees throughout Portland, Oregon, researchers with the USDA Forest Service’s Pacific Northwest Research Station and colleagues modeled the impact of tree planting on nonaccidental mortality in Portland’s 140 census tracts.
The analyses revealed that an increase in the number of trees was associated with lower rates of cardiovascular and nonaccidental mortality. This lower rate of nonaccidental mortality has economic ramifications. Based upon the U.S. Environmental Protection Agency’s value of a statistical life ($10.7 million), planting a single urban tree in each of Portland’s 140 census tracts is associated with $14.2 million in reduced mortality. Furthermore, as the trees matured, the health benefits increased.
The team also found that a commonly used vegetation greenness index derived from satellite imagery to describe the exposure of people to trees and plants may not be sensitive enough to consistently detect small changes in vegetation over time. Instead, tree characteristics observed from the ground more accurately capture what people experience while moving through the urban environment.