6 August 2019.

Science has some good news for nature lovers: trees really do make us happier.

People walk down a tree-lined street.

People are naturally attracted to leafy landscapes.

A new study based on nearly 50,000 people in the Sax Institute’s 45 and Up Study has found that while grass is great, it’s the leafy tree canopy that has the greatest benefits for mental health.

The findings come at a time when urban green spaces are growing – NSW aims to plant one million trees by 2022 and increase the proportion of urban homes that are within 10 minutes’ walk of open, green spaces. Other cities have similar plans.

Good things are happening in our cities, but when it comes to choosing between an open playing field, urban forest or a tree-lined street, are all green spaces created equal? “Many studies suggest that more green space is good for our health,” say researchers Professor Thomas Astell-Burt and Associate Professor Xiaoqi Feng, both of whom are NHMRC Fellows based in the University of Wollongong’s School of Health and Society. “But we lack evidence on whether some types of green space are more health promoting than others, so we wanted to address this gap in knowledge.”

The wood for the trees

To do this, the research team used the Sax Institute’s 45 and Up study to analyse 46,786 adults living in Sydney, Wollongong and Newcastle. The aim was to explore how location shaped mental health and general wellbeing. 45 and Up is the largest ongoing study of healthy ageing in the Southern Hemisphere, and thanks to the study’s rich psychological distress data, researchers were able to get a clearer picture of mental health patterns in ageing Australians.

Their results suggest that types of green space really do matter to mental health. Adults who lived in neighbourhoods with 30% or more tree canopy had 31% lower odds of developing psychological distress. They also had 33% lower odds of developing fair to poor general health. As for grass? Results showed that adults had poorer mental and general health in areas with higher percentages of bare grass nearby.

Why trees?

There are a few reasons why trees are so restorative. The most obvious is they offer shade from the sun. However, Professor Astell-Burt and Professor Feng point out that the shapes, colours, smells and sounds of rustling leaves also provide a natural distraction from our thoughts (particularly stressful ones) and attractive spaces for social and physical recreation. That’s not to say that bare grass is bad for mental health – it could just be that outside of sport and exercise, we seek more complex natural landscapes over a big patch of turf.

“These results suggest, ideally, that everyone would have easy access to parks with lots of trees,” say Professor Astell-Burt and Professor Feng. “The walk from home to parks and other places would also, ideally, have plenty of tree canopy overhead to provide natural shade.”

Both Astell-Burt and Feng are pleased to see new green space initiatives happening across Australia, and hope the findings will be useful for urban planners and landscape architects designing urban greening strategies.

Luciano Melo, Program Manager of the 45 and Up Study, says this is a great example of how 45 and Up can help researchers understand mental health experiences and offer up solutions for improving public health. “The 45 and Up Study is a world-class resource for researchers,” he says. “Not only is it ethics-approved, it’s also available faster than conventional research, meaning researchers can access a wealth of data that will continue to answer important health questions.”

Professor Thomas Astell-Burt

Associate Professor Xiaoqi Feng