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Trees in Hard Landscapes: A Guide for Delivery

Posted: 17th September 2014

Sue James

Trees and design Action Group

The Trees and Design Action Group’s latest publication Trees in Hard Landscapes: A Guide for Delivery which will be freely available on the TDAG website from 14th September 2014 is a companion document to the earlier Trees in the Townscape: A Guide for Decision Makers.

“Most of us tend to take trees for granted. We start to feel strongly about them only when they are felled or mutilated.

But many of the trees and avenues which in summer and winter are a part of the present scene would not be there at all but for people in days long gone by who planted them because they had a thought for the future…

Hardly a street could not be improved, if someone would give thought to planting the right trees in the right places… (in) new development there will be a chance for growing trees in areas almost treeless until now.

This book describes various ways whereby trees can be used, at relatively little cost, to make towns beautiful.”

The above is not a quote from the Trees and Design Action Group (TDAG) documents, although it could be, but from a Ministry of Housing & Local Government book, Trees in Town & City, published in 1958. Much of what we are talking about today, and one of the reasons that TDAG was formed, were explained in 1958 but there is a difference. In 1958 the discussion was about the contribution that trees could make to beautify the urban area and to make pleasanter places for people. This remains an essential role of urban trees today but we now have additional challenges especially those presented by climate change and the need to make our towns and cities more resilient. In a CIBSE Presidential Blog George Adams described the need for both mitigating climate change by reducing CO2 emissions and adapting to climate change to respond to consequences such as flooding and over-heating of the urban environment. In this context the strategic planting of trees (as well as other elements of green infrastructure) can provide many benefits – conserving and reducing energy, cooling the external environment; reducing cold winter winds, improving air quality, reducing the rate of surface water runoff and so on.

Research at the University of Manchester showed that a 10% increase in canopy cover could help Manchester to ‘climate-proof’ the city to 2050. In London the canopy cover has been estimated at about 20% and the Mayor is committed to increasing it by 5% by 2025 and a further 5% by 2050. The important point to recognise and act on is that canopy cover needs to be distributed more evenly across our urban areas – hence the encouragement in 1958 to take the ‘chance for growing trees in areas almost treeless up until now’.

There is also significant research and valuations undertaken in some American cities that demonstrates the potential benefit of strategic urban tree planting and that it is holistic cost effectiveness. These assessments have been carried out in some UK towns and cities and there is a London wide evaluation underway currently.

However the places that most need and would most benefit from trees are those areas of hard landscape which are also the areas that present the greatest challenges because, as we try to plant more trees for all the reasons given, we are doing so with a much more complex situation below ground. Utilities – water, gas, sewerage, electricity and communications lie under the streets of our cities often without coordination for either mapping or access. TDAG is calling for a more sustainable integrated infrastructure where ‘grey’ and ‘green’ infrastructure can work better together. This will involve not only mapping the ‘underworld’ but positively ‘designing’ it.

The key to doing this and therefore to better protecting existing trees and also planting more trees will be through collaborative working. Just as buildings require cross-disciplinary inputs so does the public realm and the planting and protection of trees.

The built environment and the landscape professions have a unique opportunity to work together for a sustainable future for our urban centres. With carbon still on the up, energy use and population continuing to grow we must take real and strategic action to counter the growing imbalance between consumption (what we want) and reduction (what we need). Trees are amazing and have a very important role to play in our attempts to stabilize the environment.

Trees in Hard Landscapes: A Guide for Delivery was produced by TDAG in partnership with the Institution of Civil Engineers (ICE), the Chartered Institution of Highways and Transportation (CIHT), the Chartered Institution of Building Services Engineers (CIBSE) and the Institute of Chartered Foresters (ICF) in recognition of the need for cross-disciplinary working. Indeed this guide is for all who work in the built environment – engineers, architects, landscape architects, urban designers, quantity surveyors and tree specialists - and it focuses on four areas for delivery: collaborative working, above-ground design issues, technical solutions particularly integrating trees below ground and how to approach selecting the right tree species for the right place. It offers 32 case studies and highlights the advantages of innovation. It demonstrates innovative funding methods and emphasises the importance of enhancing returns on investment by achieving multiple benefits. For example, in the case of new trees, these can be planted in a rooting environment that also helps to manage surface water runoff; combines with the installation of a cycle route which will benefit from the shade the trees will provide over time. The opportunities are there if everyone involved has the mind-set to take them.

The central challenge for us all is to achieve a sustainable future and this means that we need all our practical and available methods to minimise and adapt to the significant impacts of climate change.

Contributor: Sue James trained at the Architectural Association and worked in private practice in West Wales focusing on sustainable buildings in context. In parallel she has been a consultant for the landscape practice Lovejoy (now Capita Lovejoy) where she and Martin Kelly formed the Trees and Design Action Group in 2007. She has also advised Ecobuild on the conference and seminar programme for many years. The focus of her present work is on the collation and dissemination of research and information. She is a member of The Edge.

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