6 June 2022

How the ACT's 'modest' tree canopy target will fail, and what to do about it

| Ian Bushnell
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Suburb of Wright

The suburb of Wright will struggle to reach a little more than half the tree canopy target. Photo: Ian Bushnell.

The ACT’s 30 per cent tree canopy target is too small, but despite this, some new suburbs will struggle to reach it without changes to proposed legislation and planning rules, according to the peak architecture body.

The ACT chapter of the Australian Institute of Architects says in its submission on the draft Urban Forest Bill, which aims to protect Canberra’s trees, that tree cover should be equal across the ACT, but there did not seem to be a clear plan for retrofitting appropriate tree infrastructure in newer areas.

The Institute says the target of 30 per cent canopy cover by 2045 is comparatively modest, pointing to Melbourne and Ballarat, which are aiming for 40 per cent by 2040, and Hobart for 40 per cent by 2046.

It says the Alastair Swayn Internship Research Project found that in the Molonglo Valley suburb of Wright, 30 per cent would not be possible and that the nature of newer suburbs, with their smaller section width, smaller block size and the significant amount of space dedicated to roads/driveways, meant that there wasn’t enough space available to plant the number of trees required to hit the target.

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Wright would struggle to reach 19 per cent, and even if Variation 369 had been in place, the suburb would only just clear the target at 32 per cent, a figure inflated by trees in parks/surrounding nature reserves, which boost canopy cover numbers but provide little cooling benefit to occupants or dwellings.

The 30 per cent figure may not be achievable in other suburbs that do not have the benefit of a significant public urban forest, the study says.

The Institute is calling for the recently approved Variation 369, which is meant to ensure residential blocks have sufficient trees and open space, and the Urban Forest Bill to be integrated and simplified to define a Green Plot Ratio.

“This would be a more inclusive approach considering all vegetation and soils as part of the urban forest and the importance of biodiversity rather than just focusing on individual trees as indicated by the strategy,” the submission says.

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The Bill should include measures to retrofit recently developed areas with little or no tree canopy, and there should be greater coordination with ACT government agencies to improve tree canopy on residential streets and public land.

The submission also says that Variation 369 and the Urban Forest Bill need to align with the coming planning reforms to minimise hard surfaces for car parking, driveways and turning circles.

“The success of our urban forest is linked to our ability to reduce driveway hardstand on private blocks,” the Institute says.

This could be achieved through parking forward of the building line to enable shorter driveways, shared driveway and street parking options allowing parking to bedroom ratios to be relaxed if parking demand is reduced by alternative transport modes and work-at-home strategies, and relaxing the requirement for a minimum of one covered car space.

To help prioritise land use for soft landscaping and trees, the Institute says the government should focus on balancing building plot ratios with green plot ratios, including site coverage, for trees; creating incentives for smaller dwellings with provision for dual occupancy and secondary residence unit titling; and replacing the capped number of housing storeys with building envelope controls, along with an allowance for attics and basements.

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The Institute also says the growing size of Canberra’s houses needs to be addressed.

“Canberra needs housing that is affordable, sustainable, and of high amenity that is achieved through clever design strategies, including smaller, energy-efficient, low carbon dwellings; cost-effective, space-efficient and quality-controlled mass housing; and the adaptation of existing housing stock to accommodate multi-generational
families, and support ageing-in-place,” it says.

It added that the legislation may also have unintended consequences, such as property owners, including the government, not planting trees because of fears that they would prevent future development or expansion.

Protecting such a large number of trees in older areas like the inner south could also limit the transition to a more compact city.

The Institute warns that the legislation does not define a replacement tree size which may lead to inappropriate species of different sizes being planted.

It wants to see tree quota or canopy quota (minimum/maximum) tied to block size to help ensure equity across Canberra.

“Existing blocks that have many more trees and canopy (than the 30 per cent) should not be penalised for contributing more to our urban forest,” the Institute says.

Submissions for the Draft Urban Forest Bill closed on 2 June.

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The ACT Tree Protection unit has only two people in it for all Canberra and they are run off their feet. Over 1000 trees were ripped out on Northbourne Avenue in the building of the 12 km tram. The reality in Canberra does not follow the narrative when it comes to trees or most things. In other words, don’t take at face value what you are being told. Demand the evidence to back up any claims made by the government. It has come to that, unfortunately.

I thought Canberra was the leafiest city in the world, a UN international tree city and the worlds most sustainable city.

So all in all, I don’t think we’re doing too bad. Let’s build smaller more affordable housing.

Hi, aims of the tree policy is to keep Canberra cooler, and to create habitat. With respect to the first aim, there is a lot of bitumen and concrete that could be shaded, starting with car parks. What about a sign at the entrance to each car park, showing the percentage of tree cover it has and the surface and air temperature? I believe some cities have a tax on the unshaded summer area in such parks. Car parks can also be designed/modified to capture more water, which will help tree growth. And there could be intensive planting of trees to shade roads, where there is a lower speed limit, and space for planting.

So as luck would have it you can’t make the developers and the greens happy at the same time..

What is with the fixation on trees? They attract pests like termites, rodents and possums which all cause damage to the house. The trees themselves cause significant damage either due to falling limbs, leaves blocking drains and creating a fire hazard and worst of all, roots damaging underground pipes and shifting foundations. What are the benefits? Something pretty to look at? Seriously baffled!

The short answer is that trees are the Earths lungs, providing us with oxygen. Here’s a good book that goes into a lot more detail about how important trees are: https://en.wikipedia.org/wiki/Guns,_Germs,_and_Steel

@higgo, there are plenty of trees across National parks and reserves across Canberra. Not to mention 1/5 of NSW forests burned down during the 2019 summer bushfires and nothing happened? I doubt having a couple of saplings which will take 20 years to mature outside the front of my house is going to offset the rate of deforestation in the Amazon? The jury is still out by the way on the contribution of trees to the oxygen cycle. As sea temperatures rise there are more algal blooms and alga and plankton actually produce more oxygen than trees into the system.

https://oceanservice.noaa.gov/facts/ocean-oxygen.html More than half of the oxygen is produced by plankton and algae in the ocean. A fact that left wing radicalism will never tell you!

Sam, trees in urban areas provide significant benefits, particularly when appropriately located (also lessening some of the problems you identify).

They reduce local temperatures, reduce energy bills, increase biodiversity, reduce both air and water pollution and increase overall liveability and amenity outcomes.

And that’s only for a start.

I’m actually surprised to see anyone query this to any serious degree.

Chewy, by appropriately located it means not within 20m of the house where it can damage underground infrastructure. And if it’s 20m away it’ll take at least 30 years before maybe an oak tree will provide any sort of benefit to cool your home as you’ve described. However none of the native gums and other crap the council is planting in the newer suburbs will do that. If you like the biodiversity of having termites, roaches and rats in your house then to each their own!

Sam, that doesn’t make any sense as trees are already not meant to be located near underground infrastructure and choosing the right type of species significantly reduces that risk anyway.

And I’ve never had or seen termites, rats or roaches in my house, caused by nearby trees or otherwise. It’s pretty easy to maintain them to avoid any problems, maybe it’s just you.

Yep, it is probably just me since I have experience in the building industry. If you’ve never had your hands dirty then you probably never been in the crawl space under your house or in the roof where you will find spiders, insects and all sorts of vermin hanging out. Sure I like to maintain my house but same can’t be said of tenants in my rentals.

I agree if you don’t have experience in the building industry or haven’t got your hands dirty then you may not know these things.

Lucky I don’t have to worry about that.

Although glad to see in your last comment we seem to get to your real point.

It costs you more money to maintain your rentals properly. I thought as much.

But on the flip side of that as I said, trees increase overall amenity and liveability outcomes, which means they increase the value and amount you can earn on rent for those properties as well.

I have been in the crawl space under my previous house, more than once (under some other houses too, over the years), and I never saw any rats or other vermin. Except borers in the floor boards. That’s why I was under there; despite my suffering some claustrophobia. Spiders; yes there were some, but that’s natural. So what! That’s nothing. Not even worth mentioning. Spiders are almost everywhere. Walking through some bushland today I walked into several webs. Didn’t worry me a bit. They help keep other insects down. Sounds like your phobias are far worse than my tendency to claustrophobia. Been in a roof space too. (My present house though has neither space.)

HiddenDragon9:42 pm 06 Jun 22

Here we go again – Canberra’s Green-Left establishment tying itself in ever-more convoluted knots of contradictory and impractical rules in its attempt to maintain the mirage (if only we try hard enough) of Gaia-Nirvana in the “Bush Capital” while ensuring that a steady flow of the folding stuff keeps finding its way into the relevant pockets through ever-increasing urban densification.

Particularly entertaining is the overdue (by about 20 years) acknowledgement that –

“… legislation may also have unintended consequences, such as property owners, including the government, not planting trees because of fears that they would prevent future development or expansion.”

Give them a few more years, and they might even wake up to the fact that trees are either not being planted, or being removed earlier than they otherwise would, by people who simply want to live in their existing home (i.e. not just those contemplating redevelopment or extension) without the dangers and serious maintenance costs that come from over-sized, badly located trees which cannot be touched due to current tree protection rules – let alone what is coming.

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