Western Australia's coastal city of Perth is no stranger to scorching summer days, with temperatures often nudging 40 degrees.
But there are concerns a diminishing percentage of leafy canopy across the city, replaced by pavement and new housing, could make hot days unbearable.
Data has shown, of all the capital cities, Perth has the least tree canopy, with less than 20 per cent of its area covered.
And it's a number that is declining.
The downward trend was thrust into the spotlight at a conference, put on by the Western Australia Local Government Association (WALGA), on Friday, with experts from around the country meeting to discuss strategies to turn it around.
Curtin University Dean of Sustainable Futures Josh Byrne, who was one of the keynote speakers at the event, said turning the trend around was crucial to keep the city in a liveable state.
"Tree canopy helps make cities liveable, by shade, by making spaces cooler," Professor Byrne said.
"It's also good for our health and wellbeing."
Research has found trees and vegetation can lower local land temperatures by up to 5-6 degrees Celsius on days of extreme heat.
Finger pointed at development
The loss of canopy at the hands of development was the topic of most contention during the conference.
"Tree canopy is declining largely through land clearing for development," WALGA president Karen Chappel said during her opening address.
"Sadly, 85 per cent of canopy lost has occurred on private land."
There is currently very little state planning policy, and limited local planning policy, to stop felling of trees in backyards in Perth.
Perth's population is forecast to grow to 2.9 million people by 2031 and 3.5 million people by 2050, with urban infill needed to limit city sprawl.
But Town of Victoria Park Mayor Karen Vernon said clearing on private land was undoing local government heavy lifting.
"Every dollar we are spending on trees as local governments we are fighting a losing battle," she said.
"So (policy changes or incentives) will have to be something to be investigated.
"If we don't lose as many, we don't have to plant as many."
She said protection of trees on private land could be achieved through state or local government laws.
New density codes to help
WA Planning Commission chairman David Caddy agreed Perth's planning policy was not currently mitigating the urban heat island effect well enough.
He said he hoped the new medium density codes, set to be released "very soon", would go some way to addressing the problem.
"The medium density code does contain certain levers that will retain significant trees on private property," he said.
"Where those trees cannot be retained, let's say a tree is in the middle of a lot, then obviously, the policy requires that a significant tree be planted within the garden area."
Mr Caddy said the Planning Commission sees individual local government strategies for tree retention, like what is currently being done in the City of Nedlands, as the best approach.
"But at this stage, the commission is not going to take an approach through legislation, apart from subsidiary legislation, we're not going to take an approach for wholesale legislative change."
City of Sydney a shining success
The City of Sydney is also being looked to as a blueprint for how to increase canopy in Perth.
The council has a target to achieve 27 per cent canopy cover by 2050 in inner Sydney, from a 15 per cent baseline in 2008.
City of Sydney urban forest manager Karen Sweeny said the canopy was already on the way up, having put a broad and well-planned range of measures in place.
"So we're really making sure that we focus on all of the places that we can plant the largest trees possible," she said.
"We have tree removal as a last resort option."
She said part of their success was the planning controls in New South Wales that protected trees of a certain size being cleared from private, urban land.
"I think planning controls often make one of the biggest changes, particularly because that's the majority of land use," she said.
Research done, time for action
Professor Byrne said he felt as though there was a real drive for action during the conference.
But it would take a concerted and strategic effort, involving the whole community, to get the right balance between competing pressures.
"What we haven't quite landed on is how we get the various parties, and levels of government, to really get the right planning mechanisms in place to not only support a halting decline of tree canopy, but see an increase," he said.
"The other piece of this puzzle is how do we manage the water needs of green space and tree canopy in a drying climate, with pressure on our water supply.
"So we need to be more innovative."
