A large audience enjoyed this very interesting talk given by Marcus Grant to the Bristol Tree Forum last week.
Marcus is Deputy Director of the World Health Organisation Collaborating Centre for a Healthy Urban Environment, based at UWE in Bristol. The talk looked in particular, at how city trees can improve your health. By referring to a wide range of scientific studies which support the view that trees, particularly urban trees, can have a positive effect on health, the audience was ably taken through the complex and discursive subject of the various influences on human health, but quickly focusing specifically on the often negative effects of the urban environment on health, and how these can be partly mitigated by trees:Some of the main positive effects of urban trees that have been demonstrated by scientific research are:
• Improved physical wellbeing through atmospheric improvement by restoring street level oxygen concentrations which can fall by up to 10% due to urban gaseous pollution
• Decreased pollutants, especially diesel particulates (typically by 15 to 20%), and reducing asthma caused by ground level ozone (produced off hot tarmac surfaces) – note however, some pollens can trigger asthma.
• Trees in cities reduce summer heat-wave temperatures by as much as 7oC reducing discomfort and more importantly, heat related deaths.
• Trees, by their shade, provide us with shelter from u.v. light.
• Evidence indicates that a well treed neighbourhood actually promotes walking and cycling; very good for health.
• Improved mental wellbeing. Studies show people feel less sad, depressed or stressed around trees. Hospital patients have been shown to recover more quickly if their window has a view of trees.
• Street trees can reduce stress and hyperactive behaviour in children and even improve their educational attainment. This all contributes to the concept of visual amenity provided by trees, recognised in planning law for many decades. Now scientific evidence supports this view.
• Drivers tend to drive more slowly in tree-lined streets.
• There is a positive correlation between the number of trees lining a street and reduced levels of crime.
Additionally in these hard pressed times there are proven economic benefits to the property owner. Trees provide:
• shelter from the wind in winter (even without their leaves) saving heating costs of up to 5% and in the summer, the cooling effect of urban trees can reduce electricity costs through less reliance on air conditioning.
• And there are cost benefits to water companies as they filter pollution from rain water run-off.
Bristol needs a forward looking agenda for the benefit of its residents; a well treed city is a healthier city and there is now ample evidence to support the civic planting of trees on a much larger scale than in the past. Bristol City Council, who manage approximately 30% of the land area of Bristol, are indeed showing a much greater commitment to urban tree planting, as was explained, with lots of examples, by Russell Horsey, who gave a short talk on the ‘Trees for Bristol’ policy. His very encouraging report demonstrated the importance BCC has come to place on tree planting in the last five years. They have transformed their old approach which would eventually have lead to a treeless city. Russell described their planting initiatives which are achieving a net increase of 800 trees per year (and plenty of them will grow to be large). They are getting funding for trees to go alongside new road schemes, bus routes and build outs. This all recognises the fact that a tree brings its best benefits to a city if its canopy covers tarmac or concrete and it is planted next to a road (or in a car park). And the Council now encourages the involvement of the community in shaping their tree policies, and indeed in helping to plant smaller local schemes.
This still leaves 70% of Bristol land which is privately owned and managed by landowners like the railways, hospitals, non-state schools, homeowners, churches, car park companies, supermarkets and businesses.
Currently we are not aware of any forward looking tree strategies being proposed by any of this private sector. We would love to hear of some and we want to encourage many landowners, if not all, to replicate what the council are now doing, but in their own way.
The Bristol Tree Forum was set up four years ago by the Council to engage with the local community. It is currently chaired by Clive Stevens, a local resident, business man and volunteer (like all the other members). Its purpose is to persuade and influence landowners in Bristol to increase the city’s tree cover. We need to involve more residents to achieve this aim. Clive says; ”As we live in a democracy we will only achieve these health benefits by cajoling our Councillors and MPs into making sure trees are better protected and more are planted. To do this we need a significant part of Bristol’s populace to support this goal. We will be laying on more talks and events to help in a small way to make Bristol a better place to live in. Membership is now open to individuals so just get in touch, it's free and you don’t even have to come to our meetings, you just have to care about our and our children’s future.”
Bristol Tree Forum : http://www.bristol.gov.uk/page/bristol-tree-forum.
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