A new study published in the journal Nature has a shown a strong correlation between an abundance of street trees and local residents’ improved sense of well-being. In fact, the study’s authors found that planting 10 more trees on a city block “on average, improves health perception in ways comparable to an increase in annual personal income of $10,000 and moving to a neighborhood with $10,000 higher median income or being 7 years younger.” Now not that we really needed any further reasons to plant more trees, but the study makes a pretty compelling case to present to your local government or good motivation to get planting yourself!
While we tend to intuit that we feel better in the presence of trees—and we know that “leafy” suburbs are generally more desirable and prestigious—the study’s authors set out to quantify “the relationship between health and neighborhood greenspace,” and in particular to look at the effects of street trees, rather than other urban green spaces such as parks. The study examined the self-reported health perceptions of over 31,000 people in Toronto, Canada. A Canadian city was chosen because of the country’s universal access to publicly funded healthcare, which gave a more equitable starting point for the study.
In looking at the effects of street trees on residents, the study carefully controlled for other variables that can influence perception of health, such as age, diet and income. In addition to the sense of well-being, the authors noted: “We also find that having 11 more trees in a city block, on average, decreases cardio-metabolic conditions in ways comparable to an increase in annual personal income of $20,000 and moving to a neighborhood with $20,000 higher median income or being 1.4 years younger.”
The authors also found that the results did not apply to tree density in all public green spaces. They write, “It seems that trees that affect people most generally are those that they may have the most contact (visual or presence) with, which we are hypothesizing to be those planted along the streets. Another possible explanation could be that trees on the street may be more important to reductions in air pollution generated by traffic.” The researchers acknowledge there are limitations to their study and hope to pursue further research to reduce them. In the meantime they conclude that “street trees are associated with a significant, independent and reliable increase in health benefits in urban populations and that small increases in the number of trees along the street could improve health markedly and in cost-effective ways.” You can read the full study here.