||| FROM SCIENCE ALERT |||
Money may not grow from trees, but something even better does.
In a new study led by the US Department of Agriculture (USDA) Forest Service, researchers found that each tree planted in a community was associated with significant reductions in non-accidental and cardiovascular mortality among humans living nearby.
On top of that, the study’s authors conclude the yearly economic benefits of planting trees dramatically exceed the cost of maintaining them, by a factor of more than 1,000.
Previous studies have linked exposure to nature with an array of human health benefits. Access to nature is a major factor for mental health, and that doesn’t necessarily require the greenery to be primeval wilderness. Research shows urban forests and street trees can offer comparable benefits.
Several longitudinal studies have shown that exposure to more vegetation is associated with lower non-accidental mortality, the authors of the new study note, and some have also linked exposure to greenery with reduced cardiovascular and respiratory mortality.
“However, most studies use satellite imaging to estimate the vegetation index, which does not distinguish different types of vegetation and cannot be directly translated into tangible interventions,” says Payam Dadvand, a researcher with the Barcelona Institute for Global Health (ISGlobal) and senior author of the new study.
For their study, Dadvand and his colleagues capitalized on a well-documented tree-planting campaign that unfolded in Portland, Oregon, between 1990 and 2019. During those three decades, the nonprofit group Friends of Trees planted 49,246 street trees in Portland.
Crucially, they kept records of where and when each tree was planted. The researchers were thus able to look at the number of trees planted in a particular neighborhood, or US Census tract – each home to about 4,000 people – during the previous five, 10, or 15 years.
Using data from the Oregon Health Authority, they then associated each census tract’s tree data with its mortality rate, due to cardiovascular, respiratory, or non-accidental causes.
The results reveal lower mortality rates in neighborhoods with more trees planted, and the researchers report this negative association is significant for both cardiovascular and general non-accidental mortality, especially among males and anyone above the age of 65.
The association also grows stronger as trees grow taller, the study found. Trees planted in the prior one to five years were linked with a 15 percent drop in mortality, while trees planted in the prior 11 to 15 years were linked with a 30 percent drop.
Older, larger trees were thus associated with greater reductions in mortality. So, while planting new trees is great, this finding suggests preserving large trees that already exist is even more important for public health (as it also is for the well-being of wildlife).
While these links don’t exactly explain how trees benefit human health, the seemingly greater protection from larger trees would make sense, the researchers point out, since size boosts a tree’s ability to moderate known mortality factors like air pollution, temperature, and noise.
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Thank you, Lin. This article is beautiful and gives me hope that at least some folks are doing it right and with respect. This has been what some of us have hoped for, dreamed of, and fought for;
Maybe enough tourism pushers and road engineers and planners and developers and ‘investors’ and government representatives will read this and stop – take stock – and ask what they are doing to preserve mature trees and plant new ones. This is about interconnectedness; the trees provide shade, shelter, homes for many beings, and they clean our waters. They provide leaves to enrich the soil. The leaves provide nesting spaces for bumblebee queens and other beneficials.
It hurts my heart and my eyes (and ears!) to see projects like Victory Hill, once completely forested, logged in such a way as to make the trees look like matchsticks in a 6 feet separation lockdown – no touching allowed! This is not how trees grow naturally. Trees grow in groups; they help hold each other up from windthrow. There is so much wrong with making this forested Eastsound wetland watershed into a UGA clearcut housing project with Seattle densities – and what’s worse is that many of the housing being built are luxury condos and are still unaffordable for working people.
I urge people to visit Portland’s Japanese Garden and see how people who revere nature and trees work in concert with the land to create sanctuary and peace for all beings who benefit from trees. We need to stop the carnage and revise our zoning to LESS density in the UGA – not increase density! Once these beautiful mature diverse trees are gone, they’re gone. We in our ignorance and arrogance act as if none of this is harmful to them – and in the process of hurting and killing our trees and ripping their stumps from the earth, we harm ourselves most of all – and many don’t even seem to know it.
At least if we are having a UGA forced down our throats, we need to preserve SOME clean water and forested land. When will this be done?.
Bravo B Sadie Bailey! You said it all so well. Breathability is rather important. Plus trees bring water to earth, catching fog. (Thinking of our four month time without rain this year.) plus shade thus keeping what moisture there is in the soil.
How to keep a rational balance between development and forest area is a tough one on an Island. Economics figure heavily I am afraid.
From a tree lover: I am not surprised that trees and better health are linked. I wish that our County Councilors would not redesignate Forest Resource Lands year after year after year to zoning designations that lead to trees being replaced by suburban development. They may be thinking that more development will bring in more revenues. In the short-term it does. But in the long term, residential development demands more costly government services than do forests. Short-termism costs taxpayers more in the long run.