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How can Perth boost the city's dwindling canopy?

  • 1.  How can Perth boost the city's dwindling canopy?

    Posted 04-05-2023 11:35

    Perth tree conference investigates ways to boost city's dwindling canopy

    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.

    This street in Dayton, a relatively new suburb north east of Perth, has few trees for shade. ()

    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."

    St Leonards Avenue in West Leederville has plenty of canopy. ()

    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.

    Experts want to increase suburban Perth's tree canopy. ()

    "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.

    Perth's tree canopy is at 19.5 per cent - and reducing. ()

    "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.

    David Caddy favours a model where local governments take the lead on tree canopy expansion. ()

    "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."

    But will this be enough, for a city already battling with the heat effects of climate change? 

    Continue reading on ABC News 


    Emily Mason
    Sydney NSW