VALUING OUR TREES
04 Sep 2017
A recent study has announced that our humble urban tree populations provide $636 million of annual value to cities in the form of reducing pollution, smog and by combating the heat island effect.
Urban tree populations have always held aesthetic value for many city planners and developers, but now, as we look to future and begin to face the effects of climate change, the value of trees could be substantially more than we have previously given them credit for.
The study, which was published by the online journal Ecological Modelling, has estimated that trees in mega cities (a city with over 10 million inhabitants) provide $636 million in value. This value comes in the form of reducing air pollution, stormwater runoff, energy costs associated with heating and cooling buildings, and carbon emissions.
Ten cities were the subject of the research. Data collected from Beijing, Buenos Aires, Cairo, Istanbul, London, Los Angeles, Mexico City, Moscow, Mumbai, and Tokyo was able to inform the overall value of trees.
Furthermore, the study was able to break the value down into several figures:
- The present median benefit value from urban trees in all 10 megacities can be estimated as $607 million per year due to reductions in CO, NO2, SO2, PM10, and PM2.5
- $14 million per year due to avoided stormwater processing by wastewater facilities
- $0.6 million per year due to building energy heating and cooling savings
- $10 million per year due to carbon dioxide sequestration
When commenting on the outcome of the study, co-author Sergio Ulgiati explained that: "A deeper awareness of the economic value of free services provided by nature may increase our willingness to invest efforts and resources into natural capital conservation and correct exploitation, so that societal wealth, economic stability and well-being would also increase.”
Several international cities are aware of the benefits of incorporating mature trees and hedges into our urban centres to capture pollution and combat the heat island effect, New York City is already allocating funds to increase green initiatives in the city.
Here at home, the City of Melbourne is also taking note of the immense value of our urban canopies and using their $1.2 million Urban Forest Fund to enhance tree establishment in the city. Dr. Theodore Endreny of the College of Environmental Science and Forestry in Syracuse, New York, believes that more can be done worldwide to increase these efforts.
"If trees were to be established throughout their potential cover area, they would serve to filter air and water pollutants and reduce building energy use, and improve human well-being while providing habitat and resources for other species in the urban area," he said.
With many municipal bodies already taking notice of the value of trees, we may well see such an increase in our urban tree population in the years to come.