Adam Rogers Science Date of Publication: 05.09.17
https://www.wired.com/2017/05/trees-will-die-will/?linkId=37450892
Whether the mechanism is stress reduction, pollution reduction, or increased physical activity, somehow trees make a difference. The biophysics is less important than the epidemiology. In 2013 another researcher with the US Forest Service named Geoff Donovan took advantage of the fact that another beetle, the emerald ash borer, killed 100 million trees across 15 states in the US. Using statistical models to rule out the impacts of a whole bunch of other potentially confounding factors—race, education, income—Donovan’s team was able to connect illness with places that had ash borer infestations and concomitant loss in tree cover (which you can see in satellite imagery).
Donovan isn’t the only one on the case. A 2015 meta-analysis of the few studies that had tried to take up the issue showed that higher exposures to green space, even controlling for things like poverty and education level, indeed resulted in a statistically significant reduction in death from cardiovascular disease. Other outcomes, like higher-birthweight babies and lower rates of antidepressant prescriptions, have also shown up in the literature.