Measuring tree benefits pays dividends
It is a salutary thought that many of the most significant trees in our towns and cities were planted more than a century ago. It is also true that we live in times of economic constraint and that investment in trees is difficult to justify on aesthetic grounds alone.
The list of benefits trees provide, in addition to the purely aesthetic, (which is a real benefit in itself), are many and are well documented. These benefits are even more important in the urban environment, because that is where most of us now live.
It is useful to recap on just some of the benefits trees provide....
Trees absorb carbon dioxide and in doing so absorb one of the principle greenhouse gases. Trees provide shelter and shade and it has been estimated that they can save up to 10% of the energy needed to heat or cool nearby buildings. Trees slow down the rate at which rainwater hits the ground which helps to reduce the likelihood of flash flooding.
Health is something each and every one of us strives for. Trees filter out atmospheric pollutants. Trees shade out harmful solar radiation. Trees can have a positive effect on the incidence of asthma, skin cancer and many stress related incidences. Trees can reduce the bed occupancy time of recuperating patients in hospitals.
Property owners share a common interest in the value of their assets. Trees, it has been estimated, can increase property values by as much as 18%, with houses and homes in tree lined avenues much desired and sought after. Ask any estate agent. Trees also mask the intrusive nature of many developments where space is at a premium.
With the emphasis on land reclamation and brown field site development trees can help bind soils together and prevent erosion. Some trees can also assist in the cleaning up of contaminated land. Trees can assist in the binding and stabilisation of embankments. Trees are used widely in the creation of woodlands on landfill and other reclamation sites such as old, disused quarries.
Many of the everyday products we buy from supermarkets and garden centres originate from trees. Trees yield fruit. Trees provide horticultural mulch. Trees yield timber. Renewable fossil fuel, high value chemicals and pharmaceuticals may be the wood products of the future.
Ecosystems and ecological niches have become buzz words of our times. Trees provide valuable environmental habitats for a myriad of creatures both large and small. Trees bring the countryside to the town. Trees enhance the character of local areas. Trees soften the landscape of hard edged towns, making them greener and more attractive.
Many government advisory notes emphasise the importance of sustainable communities. Trees contribute to the landscape where people meet. Community involvement in woodland creation and maintenance is on the increase with people increasingly aware and involved in their local environment.
Archaeology is associated with digs, fossils and ruins. Yet trees provide an everyday link with both the past and the future. Ancient woodlands provide a link with craft, woodland management skills, and life styles now almost forgotten. Trees offer many clues to a historic past and can be seen for those who wish to look. Trees provide long lived memorials to those no longer with us.
So, with the benefits so many and obvious to those of us who cherish trees it is a shame that the message doesn’t always get through to the budget holders. Finances are always a problem when it comes to investing in trees. In part this may be why we have some of the lowest urban tree cover in the UK at around 10%. The average for Europe is around 20% and in the States its around 30%.
Perhaps it is the fact that the predominant argument for trees is still made in terms of aesthetics, which whilst important, fails to express the many other services that trees are providing, all at the same time and at relatively little cost.
In early 2012 a project was commissioned by Torbay Council to pilot a model called i-Tree Eco. The subsequent report expressed the benefits of the urban forest in economic terms as well as providing a comprehensive analysis of Torbay’s urban forest.
Many reports are very successful within their own terms of reference and own spheres of influence but few have the potential to cause a major paradigm shift.
This collaborative project piloted the i-Tree Eco system in the UK. i-Tree Eco is a freely available software package that has been used in over 100 countries to measure tree benefits. Assessing for tree benefits (or ecosystem services) rather than surveying for tree health or for risk management is a novel approach.
The publication of the Torbay report meant that for the first time in the UK there was a comprehensive evaluation of the urban forest, both publicly and privately owned, for a given political administrative area.
It meant that for the first time, comprehensive information on the urban forest, directly related to benefits, were quantified and expressed in monetary terms.
Torbay’s urban forest is made up of some 818,000 trees which would cost some £280 million to replace.
Torbay’s urban forest stores around 98,000 tonnes of carbon per year and sequesters around 3320 tonnes of carbon each year. Carbon storage is valued at £5.1 million annually and the sequestered carbon at £172,640 annually.
With regard to air pollution removal the urban forest in Torbay removes 7.9 tonnes of Nitrogen dioxide at a value £51,673, 22.9 tonnes of ozone at a value of £149,416, 18 tonnes of particulates (PM10’s) at a value of £1,315,767 and 1.3 tonnes of sulphur dioxide at a value of £2,123, every single year. That’s equivalent to the annual emissions from 53,000 family cars.
There is now potential to seek investment in the urban forest based on real evidence of the benefits or services it delivers. Torbay is one of the few authorities to have had significant increases in its tree budget since the publication of the report.
Since the publication of the Torbay report other projects have now been completed. Edinburgh, Glasgow and Wrexham have completed both surveys and reports. Data is currently being collected in Greater London with a report due early in 2015.
By identifying and articulating the role of trees as economic assets (or as a biotechnology to improve the places where we live and work) we can finally put them on the asset register, have the evidence to justify further investment, improve our canopy cover and make better places to live.
Kenton Rogers is a Chartered Forester and a Fellow of the Royal Geographical Society. He is also Co-Founder of Treeconomics, A Social Enterprise with a mission to work with communities, businesses and public bodies to highlight the value of trees.
For further detail of i-Tree studies in the UK please contact Kenton Rogers at firstname.lastname@example.org
Treeconomics Ltd, Exeter Science Park, 6 Babbage Way, Exeter, EX5 2FN
Tel: 01392 249170