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 30/10/2017    Last Modified: 30/10/2017

i-Tree Eco

What is i-Tree Eco?

i-Tree is a suite of open source, peer-reviewed and continuously improved software tools developed by the USDA Forest Service and collaborators to help urban foresters and planners assess and manage urban tree populations and the benefits they can provide.

i-Tree Eco is just one of the tools in the i-Tree suite.

i-Tree Eco is designed to:

  • Characterise the structure of the tree population,
  • Quantify tree benefits such as air quality improvement, carbon dioxide reduction, and stormwater control
  • Assess the value of the annual benefits derived from these functions as well as the estimated worth of each tree as it exists in the landscape.
  • i-Tree Eco is adaptable to multiple scales from a single tree to area-wide assessments.

Who uses i-Tree Eco in the UK?

Following its widespread adoption in the US and other countries, Treeconomics and Forest Research worked with the US i-Tree team to trial and proof i-Tree Eco in Torbay in 2011. Treeconomics and Forest Research have since signed a MoU with the US i-Tree Team and the Arboricultural Association to develop and support i-Tree Eco for the UK.

As a result, a wide range of stakeholders has now successfully used i-Tree Eco, including:

  • Local authorities, such as Edinburgh, Glasgow, Swansea, Wrexham
  • Business Improvements Districts (BIDs), such as the London Victoria
  • Large land asset-owning agencies, such as Highways England
  • Community groups, such as the Sidmouth Arboretum
  • Design team working on new developments, such landscape architect JL Gibbons working on Taylor Wimpey’s Chobham Manor development in East London

What do users get out of of it?

A comprehensive understanding of the tree population within the study area –The i-Tree data collection protocol ensures that findings are representative of the whole tree population regardless of ownership. The data collected provides a thorough understanding of structure of the urban forest such as canopy cover, species importance rankings, available planting space, species composition and age distribution.

A basis for evidence-led, strategic planning and management of the urban forest and associated benefits – including best practices such as:

  • Strategic management of risks – i-Tree Eco provides information on management concerns such as tree health, diversity, infrastructure conflicts and potential impact of pests such as gypsy moth, emerald ash borer, and Chalara fraxinea.
  • Strategic approach to planting – The canopy cover and age distribution information i-Tree Eco provides enables the development of achievable canopy cover targets to be reflected in policy and practice, ensuring investments are directed to areas that experience the greatest needs.
  • Robust financial planning – The value assessment i-Tree Eco provides enables adherence to asset management good practice for financial planning, thereby allocating resource for investment based on needs and in commensurate amount to the asset value.
  • Benchmarking and monitoring – The figures i-Tree provide are standardised, thus making it easy to carry year-on-year comparison and to benchmark with other tree populations / areas.
  • A Compelling set of key facts for Advocacy – i-Tree provides the information needed to develop strong headlines and a common language on the relevance of trees – allowing to communicate more effectively and engage new audiences.

i-Tree Eco and the Forestry Commission

i-Tree Eco is a software application to quantify the structure and environmental effects of urban trees, and calculate their value to society. Data from an i-Tree Eco survey can be used for making effective resource management decisions, develop policy and set priorities for a town’s trees and greenspaces.

Forest Research have entered into a Memorandum of Understanding with Treeconomics and the Arboricultural association to deliver the “i-Tree UK” project, which has four main objectives:

  • manage a development strategy for i-Tree tools in the UK
  • collate and store data from i-Tree studies undertaken in the UK
  • gather and share information about the value of the UK’s urban trees
  • promote i-Tree in the UK and help other organisations and individuals to make maximum use of i-Tree study data and reports.

Together, we are working with the i-Tree Cooperative to develop full functionality of i-Tree Eco within the UK and facilitate its use and uptake by UK users.

The i-Tree Cooperative comprises the US Department of Agriculture (USDA) Forest Service, Davey Tree Expert Company, International Society of Arboriculture, Society of Municipal Arborists, Arbor Day Foundation, and Casey Trees.

Research objectives

Our work is focussed around:

  • Working with Treeconomics and the Arboricultural to deliver the “i-Tree UK” project
  • Working with Treeconomics to deliver i-Tree Eco surveys to parks, highways, towns, cities and community forests within the UK
  • Support individuals, charities and small organisations to deliver their own i-Tree surveys in the UK
  • Undertake scientific studies to test and improve the assumptions and calculations contained within the i-Tree Eco model


This page is intended to provide guidance on the UK benefits prices for the reporting phase of an i-Eco Tree survey. Full guidance on project set up, fieldwork and reporting is available in the i-Tree Eco manual, available as free download from Details of UK training for i-Tree Eco are available from

Research objectives

Reporting your i-Tree Eco survey should include the following stages:


  • Ensure all data is entered into the i-Tree Eco programme. If this was done manually, having used paper field-survey sheets, perform a Quality Control exercise by re-opening 10% of the plots within the i-Tree Eco programme and checking that the information has been entered correctly.
  • Follow the i-Tree Eco manual instructions to generate your ‘urban forest structure’ results.
  • Follow the i-Tree Eco manual instructions to generate your ‘ecosystem service provision’ results. Ecosystem services are reported as both quantities of provision (for example, tonnes of carbon stored, tonnes of particulate air pollution removed, volume of stormwater intercepted) and as an economic value (in US $ or GB £). Default values for UK Benefit prices are built into i-Tree Eco V6, where possible. Where these are not reported or where you intend to use a more up to date or locally specific value, a Benefit price can be entered and the report re-run. Guidelines on Benefit prices are given below.
  • Collate outputs as an interim report with headline figures for discussion with project partners.
  • Produce final report.

UK Benefit prices and data sources

  • Pollution removal value: Calculated based on the UK social damage costs (UKSDC) (available from These figures were last updated in September 2015 and are periodically revised.

    UK pollution values are source and location specific, for example, the UKSDC of pollution in Central London is greater than that for a town in the north east of England. Depending on the location of your project you may want to select the appropriate damage costs.

    The default values for the UK within i-Tree Eco V6 are as follows:
    • £955 per metric ton NOx (oxides of nitrogen - UKSDC)*
    • £1,663 per metric ton SO (sulphur dioxide - UKSDC)*
    • £(n/a) (domestic sources) £73,261 (industrial sources)* per metric ton PM10 (Particulate matter less than 10 microns and greater than 2.5 microns – UKSDC; Government guidance also includes values for other sources - click here to view the Source).

    The 2015 values for the UK are as follows:
    • £14,646 per metric ton NOx (oxides of nitrogen - UKSDC)*
    • £1,956 per metric ton SO₂ (sulphur dioxide - UKSDC)*
    • £33,713 (domestic sources)* £30,225 (industrial sources)* per metric ton PM10 (Particulate matter less than 10 microns and greater than 2.5 microns – UKSDC; Government guidance also includes values for other sources).

      UKSDCs are not currently available for carbon monoxide (CO), ozone (O₃) or PM2.5 (particulate matter less than 2.5 microns). Therefore, US externality cost prices (USEC) for pollutants are reported in i-Tree Eco.
  • Carbon storage and carbon sequestration values: Calculated from a baseline year of 2014 and the respective 2014 DECC (Department of Energy and Climate Change) per metric ton value (the social cost of carbon). The default value in i-Tree Eco v6 value is £57*, it is updated by DECC every year. The 2016 value is £60* (click here to view the Source).
  • Stormwater alleviation value: Calculated based upon the amount of water held in the tree canopy and re-evaporated after the rainfall event (avoided runoff) and not entering the water treatment system.

    The cost of treating surface water runoff avoided is not reported directly by water treatment companies in the UK. Typically, FR led projects have inferred a value as the standard volumetric rate per cubic metre charge (i.e. the cost of removing, treating and disposing of used water including a charge for surface water and highway drainage) minus the standard volumetric rate–surface water rebated per cubic metre charge (i.e. the cost of removing, treating and disposing of used water).

    For example, using Welsh Water’s 2015/16 prices, this calculates as £1.6763 - £1.3238 = £0.35 per m3 (i.e. the cost of managing surface water, or the surface water rebate charge).

    However, this cost is a conservative estimate of the total ‘avoided charges’ across the full survey area as it does not account for infrastructural, operational and treatment charges linked to surface water management by local authorities, internal drainage boards and government. Therefore, the Bridgend County Borough Council and Tawe Catchment i-Tree Eco studies used the ‘Standard volumetric rate – Surface water rebated per cubic metre value’ of £1.3238 as a representative value of the avoided cost of treating surface water runoff across the whole survey area. These are charges common to water utility companies, published annually.

    Use values from the water utility company operating within your study area for reporting your i-Tree Eco project.

    Other projects, for example the London Victoria BID and Sidmouth, have used the Energy and CO2 emissions savings from reduced volume of stormwater entering combined sewers and water company information on site area charges for surface water drainage. These figures are not available from a single source nationally. They need to be calculated depending on the water utility company operating within the area of the project.
  • Building energy saving value: Domestic and Commercial average and regional UK costs are published by DECC and are update annually. The default values in i-Tree Eco v6 are set at £152.0 per MWH and £14.24 per MBTU. The values for 2016 are £147.6 per MWH and £13.57 per MBTU (click here to view the Source).
  • Replacement Cost: This is termed ‘structural value’ in the US and within i-Tree Eco, however the term has a different meaning to economists in the UK and so ‘replacement cost’ is used.

    This is the cost of the trees based on the physical resource itself (e.g. the cost of having to replace a tree with a similar tree), the value is determined within i-Tree Eco according to the CTLA (Council of Tree and Landscape Appraisers) method and the value is reported in UK £.

Funders and partners

This work was funded by the Forestry Commission. Our partners were the Arboricultural Association, Treeconomics and the US i-Tree Co-operative.

i-Tree, tree assessment, tree management, tree valuation