The effect of trees on our health

How central health is has become particularly clear in the last few months. But apart from COVID-19, health has long been a central social issue. This is also illustrated by the many books, films and podcasts on the subjects of nutrition, sports, yoga and meditation. It is often overlooked how important the immediate environment is for our health. Almost three quarters of the German population currently lives in cities, and the trend is rising. So what creates a healthy environment in our cities?

Trees!

This is hardly surprising, but it is still exciting to examine more closely. There are some very interesting and insightful studies on the impact of city trees on the health of local people.
But first, some basic thoughts on urban trees:

Trees have a calming effect on many people. This may be due to the colors: green is said to have a balancing and calming effect and trees bring this green to the center of the city.
Trees just stand there while traffic and people buzz around us. 
Trees have a different time horizon than our everyday problems and worries. You stand there, day after day, year after year, and exude a dignified calm.

Nevertheless, trees change constantly, almost imperceptibly slowly, and thereby adapt to the seasons. Trees can connect us with the forces of nature, with life cycles, with time. Trees are their own small ecosystems and provide habitats for a wide variety of animals, plants and fungi. Maybe a bird is watching you from the branches, maybe the tree is overgrown with a layer of moss or ivy, maybe some beetles are crawling over the bark. A tree brings calm and at the same time life to the city. 

Christian Morgenstern wrote: "For me, nothing is more a reflection of the world and of life than the tree."

And trees are not only aesthetically pleasing: They provide shade, dampen noise and improve air quality. Andrew Roloff writes that city trees protect us from emissions, especially by reducing ozone, nitrogen oxides, sulfur and carbon dioxide. The increasingly higher summer temperatures will make these factors more important, especially because cities are generally heat oases and heat-sensitive population groups are exposed to health risks.

But now to the exciting research on the health effects of trees:

A Study, published in the renowned science journal Nature was published, investigated this topic in Toronto, Canada. The study leaders divided an urban area into districts and counted the trees in each district. At the same time, they examined the population concerned according to health criteria. To do this, they carried out their own tests and supplemented them with data from the Ontario Health Study.

They came to the following conclusion: Ten additional trees in a block affect the health of residents on average as much as an increase in annual income of $ 10.000 or a rejuvenation of seven years.
Trees would have the greatest positive effect in preventing cardiovascular diseases. The study clearly states that people in roosts with more or larger trees would suffer measurably less from these diseases. This is important because cardiovascular diseases are the number 1 cause of death in Germany.
The study formulates the thesis that better health, especially protection against cardiovascular diseases, is based on better air quality, more physical activity and stress reduction.

Clear: Trees can improve air quality. You can also motivate people to exercise more. Perhaps to go shopping by bike because the street is in the shade and offers a special atmosphere because of the old trees. That's why it's worth planting more trees. But stress reduction because you live in a neighborhood with more or larger trees? Yes, it looks like it!  

Another interesting one Study appeared in Science, another renowned science journal. The architecture professor Roger Ulrich studied in an American clinic how the view of trees influences the recovery of patients. One group of patients had a view of trees, another group of a house wall. Ulrich comes to the conclusion that patients with a view of trees had to spend significantly less time in hospital, took less painkillers and suffered fewer postoperative complications.

There is even a term for this health-promoting effect of plants: Biophilia. The Austrian biologist Clemens Arvay describes in his book The Biophilia Effect: healing from the forest, how walks in the forest activate the natural killer cells of our immune systems and thereby strengthen our general health. Arvay goes further and describes how forest walks can prevent cancer and protect us from mental illness. His reasoning is based in part on the research results of a Japanese study, the Shinrin Yoku - or forest Baden - scientifically investigated. These study leaders explain the strong health aspects with our origins as humans. For most of our history we lived in a world that was shaped by trees. Contact with trees can relax us and reduce stress.   

Yes, trees are important to our health. They provide shade, improve air quality and dampen noise. They can reduce stress, and ten more trees in our neighborhood can - on average - physiologically rejuvenate us by seven years. And because almost three quarters of the German population currently lives in cities, it is crucial to bring more trees into our cities and to protect the existing trees.

Andrew Hunkeler
Dipl. Social and cultural anthropologist with a focus on sustainable and participatory green space design in cities. (More about the author). 
My vision is to bring together: people and trees, nature and culture, population and urban authorities.
If you have any questions, suggestions, interesting stories or exciting knowledge on this topic, please write to me: andreas@baumbad.de. I'm looking forward to your message!