Money can grow on trees

Increased leaf canopy cover is linked to a significant increase in property values, according to integrated infrastructure firm AECOM.

Utilising urban data analytics, the report ‘Green infrastructure: a vital step to brilliant Australian cities’ found that for every 10% increase in the canopy coverage within the street corridor, the value of properties increased by an average of $50,000 across the Sydney suburbs of Annandale ($60,761), Blacktown ($55,000) and Willoughby ($33,152).

The research also looked at the temperature benefits of tree canopy cover in Annandale, finding that air temperature was 4°C lower in streets with 28% canopy coverage than in streets with 20% coverage. The surface temperature of concrete and asphalt was also at least 14°C cooler in the shade.

“We found the loss of tree canopy significantly increases the heat island effect, removes vital air pollution filtering and exposes our drainage system to increased volumes of water during heavy rainfall events,” said report author Roger Swinbourne, AECOM director, Urban Systems Advisory.

“Roads and pavements last longer and cost less to maintain if they benefit from canopy cover offered by trees. The irony here is that the very development that often leads to the removal of trees suffers in the long run as the double whammy of direct sunlight and more surface water increases maintenance frequency and cost.”

The report found that the value a city derives from its urban trees is difficult to measure, due to the disconnect between the beneficiaries and the direct costs borne by the councils, utilities and road authorities who manage them. As noted by Swinbourne, those who don’t understand a tree’s collective benefits will only perceive its disadvantages, such as shading of rooftop solar, dropping of leaf litter and potential to fall.

James Rosenwax, cities leader for AECOM Australia & New Zealand and co-author on the report, added that population growth in Sydney has placed enormous pressure on existing critical infrastructure, like roads and utilities, while trees are often forgotten or undervalued.

“If we don’t put a financial value on trees, there is less incentive to protect them when looking at the cost benefits of new roads, bridges or buildings,” he said.

“Our report found that without sufficient ‘green infrastructure’, Sydney would be hotter, more polluted and could be worth $50 billion less.”

“Grey and green infrastructure need to co-exist wherever possible, especially as temperatures in our cities rise along with the frequency of storm water events,” added Swinbourne.

“To ensure the value of green infrastructure is recognised, our research found a connection between canopy coverage and the value of Australia’s favourite investment: the family home.”

Image courtesy of Mr Pauly D under CC BY-NC-ND 2.0