This simple addition to a city can dramatically improve people’s mental health

Planting trees in urban areas can help reduce stress and anxiety for the people living there, according to a new study.

An experiment in Germany suggests that simply living within 100 metres of a tree can be enough to reduce the need for antidepressant drugs.

Dr Melissa Marselle and a team of scientists wanted to see if urban flora had any discernible correlation with the mental wellbeing of city-dwellers.

Their investigations were informed by many studies that showed time spent in nature could reduce anxiety in sufferers. One found that test subjects who had spent more time in leafy surroundings showed lower levels of a biochemical stress indicator called serum cortisol. Another concluded that it even improved levels of concentration in children with attention deficit disorder.

Trees, wealth and health

Marselle, a psychology lecturer at De Montfort University (DMU) in the British city of Leicester, studied the medical prescription data of almost 10,000 residents in the German city of Leipzig and plotted that data against distribution maps of urban greenery.

The results did indeed suggest that proximity to trees corresponded with a lower rate of antidepressant prescription. More precisely, they showed that living within 100 metres of a tree – of any species – was associated with lower use of antidepressants.

Effect size of street tree density and species richness at different spatial distances around the participants’ home (buffer widths) on antidepressant prescriptions. Street tree density and richness were standardized to units of standard deviation prior to analysis. Imputed dataset (n = 9571).
The study found that proximity to trees reduced antidepressant prescriptions
Image: De Montford University


But they also found that the link was stronger in lower-income neighbourhoods.

“Our finding suggests that street trees, a small-scale, publicly accessible form of urban greenspace, can help close the gap in health inequalities,” Marselle said on the DMU website.

She concluded that “street tree planting in residential areas of cities may be a nature-based solution to reduce the risk of depression” and said it had “important implications for urban planning and nature-based health interventions in cities”.

Natural remedies

Marselle’s experiment supports the findings of many other observations, both scientific and anecdotal, that suggest reconnecting with nature is not only good for the environment but also for the body and mind.

In one case reported in The Guardian, a resident of a poor area of Baltimore found that her mental health improved so much after a programme of street greening that she was able to stop taking the antidepressants she’d been prescribed for many years.

Nature’s revitalizing properties have long been understood in Japan, where they are enshrined in the concept of shinrin-yoku, or  “forest bathing”. The practice of spending regular spells in the countryside to bring peace and relaxation is a part of everyday life for millions of Japanese.

So apparent are the changes that some experts even claim to have pinpointed how much forest bathing is necessary to restore mental wellbeing. University of Michigan scientists, who used measurements of cortisol levels in subjects, put it at 20-30 minutes of exposure to nature. Meanwhile, an investigation led by Cornell University found that as little as 10 minutes may be sufficient.

Such findings have been taken on board by medical practitioners, too. A group of doctors in the Scottish Shetland Islands have begun prescribing hill and coastal walks as a treatment for mental illness, diabetes and other conditions, The Guardian reports.

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