Tree amenity valued at £3.4 billion in the London Borough of Ealing
March 10th 2018
The Ealing i-Tree ECO Technical Report “Valuing Ealing’s Urban Trees" has just been published by Trees for Cities as part of a 3-year Strategic Partnership with Ealing Council, also involving Treeconomics, the Greater London Authority and the Forestry Commission.
This was a very detailed study building on the 2015 report “Valuing London's Urban Forest” produced by Trees for Cities with the Mayor of London and several other agencies. This showed that London’s trees captured more carbon and pollution than any other city in the world, even though Toronto for example boasted more trees.
Both studies used the American-developed i-Tree system, which is an established method of valuing the ecosystem services provided by urban trees. This suite of programmes is freely available from the US Forest Service and could be of considerable use for citizen science studies in smaller British urban areas.
The i-Tree survey involved volunteers recording 215 randomly placed 0.1 acre plots, combined with the 58% of Ealing Council’s existing tree inventory (where the size and condition data for individual trees were sufficient). There was a third data source from a parallel i-Tree Canopy survey using random points on aerial photos to estimate tree canopy cover.
The London Borough of Ealing has a population of 343,000 people and an area of 55.53 km². How much benefit do the people of Ealing gain from their urban forest?
In conventional ecosystem services, the study found total annual benefits of £1.6m, and that the cost of replacing the resource could be £259million.
Trees provide ecosystem services through:
- Conserving energy by summer shade and blocking winter winds
- Reducing flood risk by absorbing water, (estimated at £19,8000pa)
- Supporting environmental education
- Improving air quality by absorbing pollutants (estimated at 33 tonnes or £169,000pa)
- Enhancing Health by reducing stress and improving mental health and recovery times
- Storing carbon estimated at 76,670 tonnes valued at £527,000
- Capturing carbon (annually estimated at 2,250 tonnes or £28,500pa)
- Adding character and charm – bringing colour, and hiding eyesores
- Strengthening communities through boosting green spaces
- Enriching habitats and biodiversity
- Enabling urban foraging by people and wildlife
The report provides the information needed for a comprehensive borough management plan for Ealing’s urban forest in the short, medium and long-term.
The most striking result was from a CAVAT (Capital Asset Value for Amenity Trees) valuation which took in the size and health of trees and their accessibility to calculate their public amenity value. The London Plan recommends that if trees are removed for development their tree replacement should be costed on a valuation such as CAVAT which takes into account social, economic and environmental factors.
The headline valuation was £3.4 billion or nearly £10,000 per resident. Across the borough, trees on residential land (eg gardens) were valued at £1.66 billion. 25% of the amenity value of Ealings trees was for those large, accessible and mature trees in public park land.
Although many species of tree were recorded, the most valuable for amenity were oaks at £820m, beech at £292m, Alder buckthorn at 268m and lime species at £211m.
While valuations for ecosystem services and amenity may seem a bit arbitrary to the uninitiated, this study has clearly shown how hugely important trees are in making cities worth living in.
