Mayor backs largest ever survey of London’s trees & woodlands

03 October 2014

The world’s largest survey of trees and woodlands is taking place in London, backed by the Mayor Boris Johnson. The survey will reveal for the first time the total tree cover in the capital and calculate the huge benefits they bring through boosting air quality, reducing flooding, and carbon storage.

The London iTree survey will see experienced foresters and arboriculturalists join hundreds of trained volunteers to measure trees in 725 plots across every borough. The survey teams will take detailed records of each tree in their plot, including stem diameter, tree height, size of tree canopy and condition of the tree. Other factors affecting the level of benefits that a tree can deliver will be recorded, such as land use and the amount of shrub and ground cover.

This is part of the Mayor’s commitment to greening London by encouraging the planting of over 100,000 trees and the renovation and creation of green community space. Over the mayoralty, £16 million has been invested in green infrastructure initiatives including the Street Trees programme as well as Pocket Parks, Help a London Park, the Big Green Fund and RE:LEAF.

Matthew Pencharz, the Mayor’s Senior Advisor on Environment & Energy, said: “Whilst the beauty and intrinsic value of all the trees and woodland in London are recognised, most people are not aware of, or take for granted, the environmental benefits that they provide. This survey will highlight the immense value our trees bring to the our capital, and is part of our wider work to make London a greener city”

The survey will enable better planning of improvements to the number of trees in London and create a stronger understanding of their economic and environmental value. It will also help to deliver the Mayor’s target of increasing London’s canopy cover from 20 per cent to 25 per cent by 2025.

The iTree methodology has been used on a smaller scale to demonstrate the value of trees in other parts of the UK, including a study in Torbay that found that the 818,000 trees there had a structural (or replacement) value of around £280 million, stored around 98,000 tonnes of carbon per year, and removed around 50 tonnes of particulate air pollution each year. The value and ecosystem services provided by London’s trees are expected to be far higher.

Hundreds of volunteers are helping carry out the surveys, including members of the Mayor’s Team London volunteering initiative. This is one of many green projects Team London are involved with including the Wide Horizons which is helping to transform a five-acre area in South London into a well-managed woodland.

The iTree survey is being co-ordinated by the Forestry Commission with support from the Mayor of London and the London Tree Officers’ Association. The survey concludes at the end of October and the results will be published in Spring 2015.



Notes to editors

1. Partners in the RE:LEAF project include the Greater London Authority, Tree Council, Forestry Commission, Trees for Cities, Treeconomics, Woodland Trust, London Tree Officers’ Association, London Wildlife Trust, London Orchard Project, The Conservation Foundation, British Trust for Conservation Volunteers, Groundwork and Natural England.

2. The Mayor of London is greening London with a £6 million green infrastructure initiative. Further information is available at

3. The volunteer surveyors have been drawn from Team London, Tree Council wardens, members of partner organisations, and members of the public who responded to appeals. They have all been trained in iTree surveying methodology.

4. Volunteers will be collecting a range of data about each of the 750 sample plots, including the number, species and heights of the trees in the plot.

5. iTree software was originally developed by the US Forest Service to provide tools for analysing and assessing the benefits of urban trees. Free to use, it has since been used by local and national governments, other organisations and local communities around the world to strengthen their urban forest management and advocacy by quantifying the environmental services that trees provide. The Torbay iTree study can be seen at Further information is available at

6. The published results will not contain individual or personal information.

For further information visit