What is a tree really worth?
Trees are too often seen by developers as a hindrance, and by councils as a liability. To the city, however, a tree is a great asset, which make a huge contribution to the urban environment.
Aside from simple beautification, city trees offer a wide range of environmental, social and economic benefits. The existence of mature trees can and does increase property value. They help to decrease energy consumption (by shading and buffering winds), reduce the heat island effect and are essential for removing carbon from the atmosphere. Trees reduce air, water and noise pollution, absorb stormwater run-off and provide vital habitat for wildlife in an increasingly urbanized world. As we’ve written about previously, trees also improve health and well-being. Trees can even reduce crime levels in urban areas.
So what are trees really worth, and can we give them a price tag?
Methods to determine what a tree is really worth
To assess the monetary value of trees, they must be appraised against a range of criteria, including the range of benefits mentioned above, plus factors such as size, age, health and location. Standard methods have to be adopted to assess this complex question. Currently, there are a range of methods and software tools available to help assess their value.
I-Tree offers a range of free software tools that allow communities, landowners and authorities to better understand the benefits and dollar value of their urban forest. I-Tree was developed by the USDA Forest Service; an Australian compatible version was introduced in 2011. By understanding the local, tangible range of benefits that trees provide, users can collect and analyse data which helps to value individual trees and inform local policy and decision making.
CAVAT (Capital Asset Value for Amenity Trees) covers Britain and Ireland and can be used in two main ways. Firstly, it is a strategic tool to help inform the management of a town’s tree stock as an asset. Secondly, it can evaluate individual trees and give them a monetary value. Interestingly, CAVAT has been used to secure compensation from firms who have caused damage.
A number of US cities, including Philadelphia and San Diego, are using OpenTreeMap, an open source tool that allows users (including members of the public) to add trees – either individually or as datasets – to an interactive, searchable map. San Francisco is encouraging “citizen foresters” to contribute to the Urban Forest Map.
The British Natural History Museum launched an urban tree survey in 2010, with a particular emphasis on cherry trees.
While a range of tools are available, many states and local councils in Australia do not have accurate maps of their urban forest, or any data regarding the monetary value of their green assets. New tools are being developed all the time, and, combined with strong advocacy, it is to be hoped that our urban forest will become more highly valued, protected and even improved.
This is the first in a series of blogs about the value of trees from The Design Partnership. Retweet this blog and tell us what you think so we can incorporate your feedback.