City of Stirling tools up to preserve its canopy

A MODELLING tool created by the City of Stirling in Western Australia has found tree canopy coverage in suburbs with high rates of development such as Scarborough, Doubleview and Nollamara will shrink by up to 50 per cent unless action is taken now.

The City has been mapping and monitoring “significant tree canopy coverage” –  defined as cover that is taller than three metres and has a larger area than 20 square metres – for the past five years using High Resolution Airborne Multispectral Imagery.  

In that time, Stirling’s overall tree canopy has declined by nearly one million square metres. Two-thirds of this loss has occurred on residential land, mainly as a result of redevelopment, with a further 12 per cent lost from verges.

Mayor Mark Irwin said the City’s urban trees were an important asset and an essential resource, and their loss was a matter of “utmost importance”.

He said the canopy model was being used better understand the rates of loss, and where canopy was being lost.  It also showed the long-term effects of council planting programs and other efforts to reduce tree loss.

“The City learned that although we are planting 10,000 new trees each year, it’s not enough to replace the tree canopy cover being lost,” Cr Irwin said. “This is because trees take many years to grow to maturity.”

He said the tool enabled planners to see what the City would look like in the future if current trends continued or if changes were made to improve the situation.

To stem the loss of canopy cover, Stirling City Council has set a target of an average of 18 per cent canopy cover across the City by 2030. Present tree canopy coverage across all land types is 12.9 per cent.

Cr Irwin said three other local councils had inquired about the tree canopy modelling, and he encouraged others to do the same.

“It’s important to share the knowledge we have gained because all local councils are working towards a common goal – cool, leafy suburbs for the community to enjoy now and into the future,” he said.