30 January 2020

Greens put heat on government to grow tree targets in new planning rules

| Ian Bushnell
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Canberra's inner suburbs

Canberra’s inner suburbs benefit from its cooling tree canopies. Photo: Michelle Kroll.

Proposed new residential planning rules to ensure a minimum level tree coverage and green spaces are a step in the right direction but do not go far enough to protect Canberra fully from its warming climate, according to the ACT Greens.

The government released Draft Territory Plan Variation 369 – Living Infrastructure in Residential Zones for public comment in response to Canberra’s Living Infrastructure Plan, which committed it to targets of a 30 per cent tree canopy cover and 30 per cent surface permeability by 2045. At present, Canberra’s overall tree canopy sits at 19 per cent.

But the Greens say their analysis of DV369 indicates it will not achieve these targets, with the tree canopy requirement for multi-unit developments only 15 per cent.

ACT Greens planning spokesperson Caroline Le Couteur warned Canberra risked a loss of livability and amenity as the climate warmed, saying the CSIRO’s heat island map showed new suburbs were hotter than older ones because there were not enough trees.

Older suburbs were also at risk from knockdown rebuilds, whether single dwellings or multi-unit developments.

Ms Le Couteur said DV369, which applied only to residential land, should cover the entire built environment to include business, commercial and industrial areas.

“It needs to cover all of Canberra,” she said.

Ms Le Coutier also criticised the zone-by-zone approach taken by the government, saying the 30 per cent tree canopy requirement should be part of the estate development code.

“The government’s proposed planning rules are not good enough to ensure a suitable future tree canopy. They aren’t consistent with the tree canopy targets. We’re calling for improvements to ensure Canberra has sufficient trees in the future,” Ms Le Couteur said.

Minister for Climate Change and Sustainability Shane Rattenbury is concerned that without a higher level for multi-unit sites, heat islands will be generated.

“Those large density sites need to allow more space for trees on the ground or incorporate green building features such as living walls or roofs that can be important in breaking down that heat effect,” he told ABC Radio.

“It’s important we get these targets in place because Canberra’s future is a hotter, dryer future.”

Ms Le Couteur said the government needed to provide more detail about how green walls and roofs would be treated under the Living Infrastructure Plan, so developers could more easily comply with the requirements.

The Greens will be making a submission and Ms Le Couteur is confident of achieving a better outcome than that proposed.

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George Watling3:45 pm 27 Apr 20

Regarding gum trees fire risks and cooling effects all the ‘common sense’ views posted here are wrong.
+ It’s been proven by Australian scientist that
– gum trees in suburban streets are not a fire risk
– exotic trees are the true fire risks
– gums can provide substantially more shade then exotics
In a 2019 RiotACT article titled ‘Native trees best suited to beat Canberra’s intensifying heat, says report’ Associate Professor Cris Brack from the ANU’s Fenner University’s Fenner School of Environment and Society clearly states that eucalypts trees in streetscapes are ‘not a fire risk’.
In a 2013 study undertaken by researchers from the University of Technology Sydney it was demonstrated that:
– the dried leaves of exotics catch fire much more quickly than the dry leaves of gum trees,
– green leaves on gum trees are no more combustible then green leaves on non-Aussie exotics like oaks, ash trees, and maples.
In a 2016 CSIRO Victorian field study that compared the shading and cooling effects of gums to maples CSIRO scientists found that the maples included in study could not provide the same amount shade as the gums included in the study.
While the gums in the study were able to block 86% of the solar radiation hitting their canopies from hitting the ground the maples were only able to block between 70% and 33% of the solar radiation hitting their canopies from hitting the ground.
The title of the 2013 UTS study is the ‘Differences in Leaf Flammability, Leaf Traits and Flammability-Trait Relationships between Native and Exotic Plant Species of Dry Sclerophyll Forest’. It was published on 18 November 2013.
The 2016 CSIRO study’s title is ‘Greening the West – spatially optimised tree plantings to minimise urban heat island effects’. It was published in July 2016.

Reply to Julie Macklin.
I agree, the growth in house size is a significant issue contributing to the decrease in plant coverage in residential areas, especially tree coverage.

However it was very predictable that the reduction in block sizes would make the situation much worse.

Perhaps if the Greens feel so strongly about this issue they should make it one of the conditions for their support of Labor next election that the government department responsible for approving house plans takes a stronger stance on what percentage of a block can be occupied by a house.

It would be very interesting to see the Greens publish a table of how big a house they would be willing to allow to be built on the typical block sizes in our newer suburbs.

Surely in the interests of openness and honesty they will have no qualms about providing that information in the lead up to the next election.

HiddenDragon7:34 pm 02 Feb 20

More trees on sellable/developable land would mean less revenue for developers and, in turn, for an eternally cash-hungry ACT Government – and that’s just not going to happen.

In the end, money will win out – and the Government will simply double down on the already over-the-top regime for protecting trees of arbitrary size on established blocks. That, in turn, will have the perverse effect of discouraging tree plantings by people who don’t eventually want to be stuck with a problem tree.

What incredible hypocrisy! The Greens have allowed development of urban wastelands where blocks are too small and houses to big to have room for a potplant, let alone a few actual trees.

Have the so called Greens only now worked out that fewer trees mean hotter temperatures? Duh. Why have the Greens been supporting Labor/Geocon apartmentalisation and densification of Canberra. Greens means hypocrisy.

Elizabeth Ann Thurbon11:35 am 01 Feb 20

Living in an apartment at C5 our community is built around a beautiful park. While we really need some more shade and trees in our park it is a wonderful model that gives fantastic green space to residents and this park is the focus point for all of the CAMPBELL community. There are about 1000 people living in apartments around this green space who no longer water gardens or full swimming pools.

Having lived in several Canberra Suburbs ranging from ones established over 50 years ago to very new suburbs, it has been my experience that as the size of the house blocks has decreased, so has the amount of trees and other plants.

The street in Mawson I lived in had yards with far more greenery than what I am seeing in the newer suburbs of Molonglo.

Take a cruise around Canberra using Google Maps and take a look at the differences.

The push to restrict urban sprawl by decreasing block size does appear to have also reduced the plant coverage of those suburbs.

But that should not be a surprise, it seems very predictable.

So what is that the Greens want? Houses with lots of greenery around them, which will tend to be most practical on larger blocks, or denser, Molonglo style suburbs with less greenery?

Agree mate. It’s due to developers and more so the government squeezing as many blocks to each section with only one thing in mind and that us to create as much revenue as possible.

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