A new study carried out in Australia found that cities that have lots of tree cover are healthier psychologically than those that don’t.

Researchers at the University of Wollongong (UOW) found that people living in urban areas have a lower risk of developing psychological distress and better overall health if they have trees within walking distance of their homes. They concluded that in areas that have tree covering of 30% or more, adults had 31% lower odds of developing psychological distress, and 33% lower odds of rating their general health as “fair” or “poor” over six years. Surprisingly, they found that areas with lots of green spaces with open grass do not provide these same health benefits.

In the study, researchers tracked the health of 46,000 people aged 45 and older living in Sydney, Newcastle and Wollongong. It was led by Professor Thomas Astell-Burt, an NHMRC Boosting Dementia Research Leadership Fellow at UOW, who said that while many other studies had found that green space was good for mental health, his looked at what specific types of green spaces provided benefits.

“Our results suggest the type of green space does matter,” he said. “We found that the residents of neighborhoods with a higher amount of tree canopy had better mental and general health, but didn’t find the same correlation when the type of green space was open, grassed areas. This suggests that protecting and increasing the urban tree canopy could potentially deliver significant community health benefits.”

One of the reasons trees are so beneficial to health is that they provide shade and lower the temperature on hot days. The greenery of the trees also provides sensory relief in cities that are full of hard surfaces, right angles, glass and concrete, and intrusive, attention-seeking advertising.

“The vibrant colors, natural shapes and textures, the fresh aromas and rustling of leaves in the breeze all provide distraction and relief from whatever it was you might have been thinking about, or even stressing over,” explained Associate Professor Xiaoqi Feng, an NHMRC Career Development Fellow at the university. “Studies back this up. Walks through green space have been shown to reduce blood pressure, improve mental acuity, boost memory recall and reduce feelings of anxiety.”

Hopefully, cities around the world will take notice of this study and start planting more trees.