It is well known that humans are innately connected with living systems – a term referred to as biophilia. This concept was identified by Edward O Wilson in his 1984 book titled ‘Biophilia’ where he details the close association of humans to nature, which includes plants, animals and weather.
Placing a value on the environmental benefits of Australia’s urban forests
By Dr Anthony Kachenko, National Environmental and Technical Policy Manager, Nursery & Garden Industry Australia.
Indeed, the importance of plants in the urban community has recently been highlighted by the Food and Agricultural Organisation (FAO) of the United Nations who consider trees and forests as an essential part of urban development, contributing to healthy cities for healthy people.
In order to successfully achieve this, the ability to economically quantify the benefits of the urban forest is required. This will not only assist to efficiently and effectively manage this valuable resource, but it will also provide a sound platform for strategic planning and decision-making at local, state and national levels. To aid this process, a software package referred to as i-Tree ECO is freely available from www.itreetools.org
This peer-reviewed software program has been developed by the United States Department of Agriculture (USDA) Forest Service and a number of other collaborators to provide users with the environmental value of trees. The tool can provide the user with the dollar value of environmental benefits associated with a single tree or an entire urban forest. The software program provides baseline data that can be used to demonstrate value and set priorities for more effective decision-making of urban forests.
There a many other benefits of being able to provide baseline date on individual trees or indeed a population of trees. Benefits include the ability to:
- Educate the wider community about the importance of trees in streetscapes and their local environment
- Justify expenditure on planting and maintaining trees in streetscapes, local parks, gardens, rail corridors, and other green areas
- Provide a business case for developers, landscape architects and engineers to include more tree plantings in design
Through Arboriculture Australia, ENSPEC Environment and Risk Pty Ltd were engaged to undertake the research, collation and formalisation of critical climatic, geographic and botanical data to be incorporated into i-Tree ECO for use by the Melbourne Urban Forest Accord Group and City of Sydney Council. ENSPEC Pty Ltd has also completed the necessary work for the Australian Capital Territory.
Nursery and Garden Industry Australia (NGIA) have engaged ENSPEC Pty Ltd to continue their work on further integration of additional Australian states into i-Tree ECO. The Australian-compatible version of i-Tree Eco was introduced at the 2011. A detailed user manual is available through the i-TREE website that provides step-by-step guidelines showing how to use the tool.
Once field data have been collected, they need to be transferred to the desktop and sent for processing. Data that is submitted is processed automatically through an online system and results are generally returned the same day.
i-Tree Eco is a powerful tool and provides key data including:
- Structure – estimates basic information on the tree (e.g., leaf area, leaf biomass, structural value, pest risk)
- Carbon – estimates annual carbon storage and sequestration based on tree biomass equations and annual growth estimates, which are based on tree condition, competition and annual growing season length
- Air pollution removal – estimates hourly pollution removal based on weather data, pollution concentration data, leaf area and location factors
- Building energy use effects – estimates effects of trees on building energy use based on distance and direction from space‐conditioned residential building
Recently, the City of Melbourne in partnership with NGIA undertook an assessment of the trees within the southern section of Carlton Gardens where the Melbourne International Flower and Garden Show is held each year.
The results indicated that the trees in Carlton Gardens South are well established and provided $5,925,392 in environmental values to the community. Many of the larger trees returned an individual value of more than $30,000 with some valued up to $60,000. The data also showed that the approximately 300 trees measured removed 242 kg of air pollution a year, currently store 620,000 kg of carbon and sequester 9,500 kg of carbon each year.
While the i-Tree Eco is based on environmental factors such as carbon sequestration, air pollution removal and the cooling effect of trees in summer, it is important to remember that other positive ways trees, and indeed, all vegetation contribute to our urban environments.
This is why the integration of Australian data into i-Tree Eco is one element of the nursery and garden industry’s ‘More Trees Please’ initiative as part of the ‘Improve your Plant Life Balance’ campaign.
For more information visit www.plantlifebalance.com.au or contact Dr Kachenko on (02) 88615100.