Valuing Oldham’s Urban Forest

During the summer of 2016, Treeconomics collaborated with Oldham Council, First Choice Homes, Forest Research and Davey to evaluate Oldham’s trees.

Using i-Tree Eco software, a total of 219 plots were selected from a randomised grid covering both urban and rural Oldham. Field data was collected by volunteers, Oldham Council staff and First Choice Homes staff, who were assisted and trained by Treeconomics. Oldham is one of 10 boroughs in the Greater Manchester area, and the first of which to undertake such a study.

Notably, the tree density in Oldham was calculated to be just 33 per ha. This is lower than densities recorded for other i-Tree surveys, and the UK average for towns and cities of 58 trees per ha. Percentage tree cover and percentage canopy cover were fairly low at 11.8% and 16.9% respectively.

Despite this, the existing treestock of Oldham provides impressive and extensive benefits. Treeconomics’ analysis determined that Oldham’s urban and rural forest filters an estimated 96 tonnes of airborne pollutants each year – a service worth more than £1.5 million in social damage costs. The trees’ filtration of sulphur dioxide alone is equivalent to that of the emissions of 41,000 cars, every year.

Since around 50% of wood by dry weight is comprised of carbon, trees can store carbon in their structures for decades or even centuries. The carbon stored across all the trees sampled in Oldham was estimated at 66,508 tonnes, with an estimated economic value of an astonishing £4,246,000.

Oldham’s trees were also estimated to intercept around 278,000 million cubic metres of rain water every year, equivalent to an estimated £420,000 in avoided stormwater treatment costs.

Conclusively, Oldham’s tree resource is providing a valuable benefit to all of its residents and visitors. The services provided by Oldham’s urban forest are worth £2.1 million every year, and their amenity value (CAVAT) was estimated at an astronomical £1.7 billion.  Understanding urban forest composition is the first step in the proactive management of this importance resource.

“This report is of great significance and all those involved are to be congratulated. I look forward to its reception in the wider public and professional domains, and feel confident that it will lead to some extremely positive outcomes for Oldham’s urban forest.” Jim McMahon, OBE MP