The Helliwell tool enables users to put a monetary value on the visual amenity provided by individual trees and/or woodland. The basic approach of the Helliwell system is to allocate scores under a number of different factors such as tree size, life expectancy, suitability to setting etc. These scores are then combined to give an overall comparative score for a tree or woodland. As a further step, it is then possible to attach a value to this score by use of a monetary conversion factor. See the website (link below) for current Helliwell point values.
Website with information about Helliwell – http://www.trees.org.uk/faqs/Helliwell-system-and-how-much-is-a-point
Evaluation of tool by Forestry Commission – http://www.forestry.gov.uk/pdf/SERG_Street_tree_valuation_systems.pdf/$FILE/SERG_Street_tree_valuation_systems.pdf
Natural England report that assesses the tool – Green Infrastructure: Valuation Tools Assessment, Natural England, 2013 – http://publications.naturalengland.org.uk/publication/6264318517575680