Exeter University i-Tree Eco Inventory Report

The University of Exeter is a public research university based in Exeter, Devon.

It was founded in 1955, although its predecessor institutions date back to 1900. There are four main campus’ Streatham, St Lukes (both in Exeter), Truro and Penryn (both in Cornwall). The University of Exeter is fortunate to manage a mature tree stock of around 10,000 trees across its Exeter Campuses. The resource includes two arboretums, a cherry orchard and a wild conifer collection. During 2009, the details of 5,021 trees on University of Exeter campuses were recorded and analysed by Treeconomics, as part of its ongoing tree management program.

Tree diversity is an important aspect of the tree population to take into account, as diversity increases overall resilience in the face of various stress inducing factors. A more diverse tree-scape is better able to deal with possible changes in climate or potential pest and disease impacts.

The tree population within University of Exeter’s grounds represents a very diverse community of trees given the area, with 328 species of tree identified.

The size class distribution of trees within University of Exeter is one of the most balanced so far recorded by these types of studies. This structural diversity should increase the overall resilience of the tree stock within the grounds, and illustrated good previous management practices.

Treeconomic’s analysis determined that Exeter University’s tree stock removes up to 2 tons of pollutants each year, a service valued at a significant £11,728. Over the lifetime of a tree, several tons of atmospheric carbon dioxide can also be absorbed. Overall, the trees of the University of Exeter were found to store 1,951 tonnes of carbon, with a value of an impressive £124,000. Of the entire tree species inventoried, the Oak species store and sequester the most carbon, adding 4.32 tonnes every year to the current Oak carbon storage of 238.77 tonnes.

Surface runoff can also be a cause for concern in many areas, as it can contribute to flooding and is a source of pollution in various bodies of water. Exeter University’s trees help to reduce runoff by an estimated 4,217 a year, with an associated value of £6,390. This is equivalent to nearly 2 Olympic swimming pools of stormwater being averted every single year. Oaks intercept a large proportion of the precipitation, reducing runoff more than all the other species.

Indisputably, University of Exeter’s trees provide a valuable public benefit – at least £20,000 in environmental services, and £20,874 in total annual benefits, each year. The extent of these benefits needs to be recognised, and strategies and policies that will serve to conserve this important resource (through education, for example) would be one way to address this.

Future management of the tree stock is important to ensure canopy cover levels continue to be maintained or increased. This may be achieved via new planting, but the most effective strategy for increasing average tree size and the extent of tree canopy is to preserve and adopt a management approach that enables the existing trees to develop a stable, healthy, age and species diverse, multi-layered population.