One of the most memorable episodes of the Radio 4 comedy ‘Just A Minute’, I ever heard was a banter between Peter Jones and Kenneth Williams about the “Hole in the Donut” – which centred on the importance of the hole above the dough. It is treacherous to start explaining jokes but of course it was funny because it was true and bizarre at the same time. How can the most important element of a thing, be what is missing? How can the space in the middle be more important than the substance that surrounds it? It sounds as if that cannot be true, but it is. What makes a donut iconic is the hole in the middle, not the dough around it.
I was reminded of that joke at a recent Woodland Trust event I was hosting which engaged the construction industry in a debate about the best use of wood and trees in their projects. As Mike Townsend, a speaker at the event and former CEO of the Trust, put it best – “Good design is not just about the buildings, but about the spaces between the buildings.” In other words, it is about the hole in the middle just as much as it is about the buildings around it.
There is something about the properties of trees that makes them a particular consideration in developing urban resilience, and important to the way in which people respond to their surroundings.
Townsend said the very size and structure of trees means they provide shade and shelter, help reduce surface water, scour airborne pollutants, and lower ambient temperatures.
This is not wishful thinking; Townsend quoted research undertaken by the University of Manchester that has shown how trees in urban areas can dramatically reduce surface water runoff, through a combination of interception and evaporation of rainwater and increased infiltration. About two thirds of flood risk is attributed to surface water flooding, so this is no little matter.
The same research has shown how ambient and surface temperatures are lower under tree cover because of shading and cooling, resulting from the latent heat of evapotranspiration from leaves. Computer modelling has shown how, as a result of this, increasing urban green space can mitigate urban heat island effect.
Without any increase in green space, by 2050 the temperature in Manchester is projected to rise by 3oC.
Many people also make grand claims for the health and financial benefits of tree planting. In general I could not agree with them more, although I am a little dubious of the precise calculations some make about the exact savings in healthcare we can make by reducing stress and asthma in particular. But I feel strongly that proper use of trees revolutionises the way we feel, behave and live.
The way we use trees in cities is becoming increasingly important, not just for the UK, with more and more of us living in an urban environment. It is important for a growing amount of people around the world.
Urbanisation is one of the defining trends of the 21st Century. The global population exceeds 7 billion, with more than half of us living in urban areas. By 2050, there maybe nearly 10 billion of us worldwide. More than two-thirds will be urbanised.
If we are to build the urban world of the future we have to do it with an eye to letting in the rural world. That is important because a green physical environment does help calm us. As our homes and buildings remain unchanging blocks, the trees around adapt through the seasons, providing not just a change of scenery but a connection to the natural world.
The effect of this on our attitudes, health and general well-being may be hard to quantify but as the work from Manchester University showed, we can measure the way trees help mitigate the harmful effects of modern development by reducing the urban heat island effect and reducing water surface run-off.
Greening our built environment should not be an afterthought, but a central idea in the new built environment of the 21st Century. In other words, let us build the hole first and then the dough around it.
Adam Shaw – Journalist, broadcaster and Woodland Trust Ambassador
Seeing Trees Constructively was an event hosted by the Woodland Trust at Lend Lease. Its aim was to bring together key stakeholders from conservation and property development to inform and discuss the role of trees and woods in land and property development.