According to a new study published in the journal JAMA Network Open, living in neighborhoods with leafy trees is linked to higher levels of wellness. The study found that not all green spaces are created equal, as leafy trees promote higher levels of wellness than abundant green space. CityLab reports: [The researchers] describe a large-scale longitudinal study featuring 46,786 mostly older residents of three Australian urban areas. The subjects were initially interviewed between 2006 and 2009; follow-up reports were taken between 2012 and 2015. At both points, participants were asked to rate their overall health, and noted whether they have ever been diagnosed with, or treated for, anxiety or depression. In addition, they completed a 10-item questionnaire designed to measure their risk of psychological distress. Among other items, they noted how often in recent weeks they had felt “hopeless, rigid, or fidgety,” “so sad that nothing could cheer you up,” or “worthless.” Researchers compared the participants’ answers to the natural features of the “mesh block” where their home is located (a geographical unit containing 30 to 60 dwellings). Using satellite imagery, the team calculated both the percentage of total green space and “separate green space types, including tree canopy, grass, or other low-lying vegetation.”
After taking into account such variables as the participants’ age, gender, education, and household income, the researchers were able to confirm the results of previous studies, finding that “total green space appeared to be associated with lower odds of incident psychological distress.” More intriguingly, they also found that exposure to low-lying vegetation was not consistently associated with any particular health outcome. Exposure to grass was, surprisingly, associated with higher odds of psychological distress. The wellness-boosting feature, then, appears to be the trees. The researchers report that living in areas where 30 percent or more of the outdoor space is dominated by tree canopy was associated with 31 percent lower odds of psychological distress, compared to people living in areas with 0 to 9 percent tree canopy. “Similar results were found for self-related fair to poor general health,” with tree-rich residents reporting better health overall, the researchers write.