The latest seminar to be held at Barcham Trees’ Cambridgeshire nursery was led by Dr Kathleen Wolf on the subject of how trees provide better human habitat based on the extensive evidence of the human health and wellness benefits. Kathleen is a research social scientist at the College of the Environment at the University of Washington, based in Seattle USA, and a collaborator with the USDA Forest Service on Urban Natural Resources Stewardship research. She conducts studies to understand the human dimensions of urban forestry and urban ecosystems, based on the principles of environmental psychology.
The day was introduced by Mark Johnston, who described Kathleen as ‘a world authority on trees, people and urban greening’ and someone who has inspired both his students and himself. He also mentioned the Arboricultural Association was following her work, and had invited her to speak at its annual conference earlier that week.
Dr Wolf began by reminding us that the public parks of Victorian Britain were known as ‘public walks’ because trees were then thought to bring health benefits – an idea which came to the fore once more in the 1990s with the concept of the ‘green gym’. The World Health Organisation has promoted a broad definition of health since 1946: a state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity. Trees are not a panacea for health issues in communities, but they are nevertheless important, and the green environment should be seen as part of the health solution.
She then considered the idea of ‘nearby nature’ and felt it no coincidence that large companies such as Boeing, Microsoft, Amazon and Starbucks are based in Seattle, which is surrounded by beautiful and spectacular nature. “Trees are in the background, but science now tells us they provide benefits across the life source from cradle to grave”, said Kathleen.
Starting with the first days of our lives, she cited the research of Donovan et al, published in Health and Place (2011), which found a 10 per cent increase in tree canopy cover within 50m of a house resulted in a lower number (1.42 per 1000 births) of low-weight births. This finding has been replicated in studies in Spain and Canada, and although we do not know the causal reasons, a low birth weight often has immune system, respiratory and mental capacity implications through the entire life of a person.
As children grow and develop, adults need to support them in their experience of nature. In his book Last Child in the Woods Richard Louv describes nature deficit disorder. Kathy remarked we no longer have ‘free range children’ who are free to roam about and explore in nature.
College students with more natural views from their bedroom windows scored higher on tests of capacity to direct attention and rated themselves as able to function more effectively, according to Tennessen and Cimprich in the Journal of Environmental Psychology (1995).
Looking at adults, and based on the work conducted by Rachel and Stephen Kaplan at the University of Michigan on Attention Restoration Theory, desk workers with no view of nature from their workplace reported 23 per cent more ailments than those with a natural view in the previous six months. We should design better office environments, and there are monetary benefits of being close to trees and nature.
Trees, it seems, can even help to reduce crime. According to Donovan and Prestemon’s article in Environment and Behavior (2012), larger trees in a public right of way are associated with lower crime rates, but smaller, view-obstructing ones are linked to increased crime. In the American Journal of Epidemiology (2011), Branas et al found that when four ‘vacant lots’ were greened in Philadelphia, there were consistent reductions in gun assaults across the four areas and consistent reductions in vandalism in one area.
In Japan forest-bathing (Shinrin-yoku) is popular, and these extended forest walks have spiritual elements. Those who walk often experience lower cortisol – a stress indicator – reduced nervous system activity, increased immune function, lower pulse rate and lower blood pressure. A Japanese study discovered elderly people who live in green, ‘walkable’ neighbourhoods tend to have less illness and lower mortality rates than those who do not, while a Scandinavian review of multiple studies has found light exercise eases cases of mild to moderate depression.
In 1984 Roger Ulrich published his report on the effects of a nature window view on recovery from surgery. Patients who had a view of trees, versus those viewing a brick wall, tended to have shorter stays, less severe pain, fewer complications and better emotional well-being than those who were deprived of one. Hospitals are now installing healing gardens, and they are popular not only with patients, but also with their visitors and hospital staff.
Kathleen Wolf then went on to look at the economic value of trees. Trees grown for commercial uses such as timber usually have an identifiable owner, who will likely exclude others’ use of the forest. On the other hand, trees in cities are public ‘goods’ with multiple ‘owners’ and are non-excludable. There are expenses involved with tree planting and care, but what about returns and profits? Studies show that garden and street trees can increase the value of residential property from two to 15 per cent.
Dr Wolf has conducted research about trees and retail environments, looking particularly at place perceptions, patrons’ behaviour and product pricing. Across several studies, shoppers claimed they were willing to pay nine to 12 per cent more for goods in business districts with a good quality urban forest canopy. The neatness of an area was also seen as important, with tree planting signalling positive change in a revitalising business area..
Kathleen concluded by reminding us there are 40 years of evidence showing the connection between nearby nature and human health and wellness. She has also become interested in how we might evaluate questions about the deeper experiences of nature – how do we measure them and how much time is needed with nature? Science and the sacred is an important blend, and something we would perhaps do well to consider. Delegates, which included tree officers, arboricultural consultants, charity representatives and landscape architects, enjoyed a stimulating and interactive day, and surely went away with a thought-provoking viewpoint passionately presented by an excellent speaker.
An overview of Dr Wolf’s research programmes can be found at www.naturewithin.info Additional work is highlighted at the Green Cities; Good Health website www.greenhealth.washington.edu
To view Kathleen Wolf’s presentation, please log on at http://www.naturewithin.info/Talks/2014.Sept.UK.Barcham%20Seminar.Wolf.pdf
