Sid Valley i-Tree Eco Survey

Sidmouth Arboretum – the country’s first civic arboretum – is measuring the benefits and true value of the trees in Sid Valley.

Established in 2010, the Arboretum is not restricted to a single site but incorporates the whole of the parish – including trees on both public and private property.

To assist in planning for the future, to know which trees to plant and where, the Arboretum has worked in partnership with Treeconomics to train volunteers to complete an i-Tree Eco survey and to identify and assess the health of Sidmouth’s trees.

During the ‘leaf on’ period of 2014 a team of volunteer surveyors visited 201 randomly selected plots, recording a wide range of tree and shrub species, their size and condition, and the type of land use.

Trees can help improve air quality by reducing air temperature (lowering ozone levels), absorbing them through the leaf surfaces and by intercepting particulate matter (e.g. smoke, pollen, ash, dust). Treeconomics estimated the value of the Sid Valley trees’ pollution removal at a considerable £720,000. Annual carbon sequestration services provided by the trees were valued at £150,000. Trees also make a valuable contribution to the reduction of storm water run off as their root systems promote infiltration and storage in the soil. The valley trees were estimated to reduce run off by 215,000 cubic metres a year. Ash and Birch are particularly good at this in the wider landscape, with Ash comprising 10.7% of the Sid Valley tree population and Birch constituting 8.9%.

As commented in the summary report:

“The replacement cost of a tree is the cost of replacing it with a similar size and species of tree. Putting a pound value on trees does help us understand that care and maintenance are real issues, especially in the urban landscape. Sid valley trees have a replacement cost of £170 million. This helps us plan and budget. The value of a mature existing tree measured on ecological services, property values, cooling, health, amenity (i.e. prettiness) – all have £ values, seldom acknowledged.”

The Arboretum are now using the results to inform a community tree strategy and recently held a Tree Summit to engage the wider public.