For the love of trees

Nature strips in South Perth are a favourite spot for bees. Photo: Ashleigh Davis.

Suburbs with low tree canopy can be up to 10 degrees hotter than their leafy counterparts. Tree-sparsity is turning many parts of Perth into ‘urban heat islands’ causing heatwaves and higher energy consumption, electricity bills, and greenhouse gas emissions. Heatwaves are only becoming more frequent and extreme, according to a recent report by the Intergovernmental Panel on Climate Change.

Researchers, nature enthusiasts, non-for profit organisations, and different levels of government are actively working to improve the sorry state of our green spaces. This is a look at some of the people driving change.

Spending time in nature is good for our mental and physical wellbeing. Research conducted in Perth found people in neighbourhoods with easy access to useable green space were twice as likely to report better general health. One of the authors of the study, research associate at The Behaviour Change Collaborative Dr May Carter, says there have been policy failures and design flaws in our newer suburbs, leading to a detachment from greenspace for many people.

“New developments need to be done differently in Perth,” she says.

“[New planning policy] is trying to address some of the issues. It’s telling developers you must consider urban ecology. You must consider where trees will be. You must consider environmental outcomes. Because we’ve seen over the last 20 years what happens if you don’t.”

Dr Carter’s study adds to a seemingly endless body of research measuring the positive effects trees have on mental health. A study of 585 Japanese adults in 2020 found every single participant reported a reduction in depressive symptoms while walking among forests. One study found those living in proximity to trees had better amygdala integrity – that’s the part of the brain responsible for processing emotional information. Medical doctor and researcher Dr Qing Li’s book Forest Bathing: How Trees Can Help You Find Health and Happiness comprehensively documents studies which suggests time among trees may help us deal with the stressors associated with urban living.

Trees are known as the lungs of the planet for good reason. Not only do they turn carbon dioxide into oxygen, they also improve heart health, and enhance physical immunity by increasing the production of anti-cancer proteins.

While the most recent Global Burden of Disease study estimates air pollution accounts for around 4.2 million deaths a year, a recent study from Harvard University has found this number may be a gross underestimation. Using a new global 3D model, researchers calculated air pollution accounted for one in five deaths around the world in 2018. In Australia and the Pacific alone, this modelling suggests fossil fuels contribute to the death of around 6,000 people every year.

Aside from the host of health benefits, mature trees add huge monetary value to properties, lower energy bills, moderate wind, and reduce localised flooding.

But generally, tree canopy is disappearing from Australia’s metropolitan areas.

According to the CSIRO’s Where Should All the Trees Go? report, the average tree canopy cover in WA is 19.95 per cent, representing a 2.23 per cent decline since 2009, with 41 per cent of metropolitan councils experiencing serious canopy loss.

To combat the problem, the State Government has recently upped its support for urban greening – dishing out $750,000 worth of grants to local councils under the Urban Canopy Grant Program and has released some new planning guidelines for developers. It is also understood more state policies are currently being drafted in this space.

However, Dr Carter wants state policies beefed up. “They are only a guideline. They’re not legislated. They’re not regulatory. If you read the policy, its intention isn’t for development to happen the way it has.

“What happens is developers can interpret [guidelines] in other ways. And they essentially go to the minimum requirements.”

Dr Carter says newer suburbs with affordable housing tend to fall into this category.

Block sizes have decreased significantly over the past 50 years. As Dr Carter notes, this is especially evident in new affordable developments, “The standard house block was, you know, the quarter acre. Now many of the block sizes are not much more than 300-400 square metres. So, once you’ve built the house – maybe four bedrooms, two bathrooms – there’s not much room for outdoor living or any room really declared a garden apart from what’s on your verge.”

A recent study conducted in Western Sydney on new housing estates – which are comparable to developments in outer-Perth suburbs – found they are particularly vulnerable to heatwaves. The paper offered several recommendations including improving urban greening, broadening community awareness, and changing development processes.

Dr Carter has spent two decades working in various roles in both government and non-for-profit sectors at the intersection between urban greening, policy writing, and community engagement. She says the role of non-government organisations (NGOs) is to “engage and retrofit.”

“It’s a really important task because it’s about creating and keeping a sense of community. So people stay healthier. So they stay connected. So they feel better. All of those things that make an area a better place to live.

“I left with a big bruise on my forehead working in the government because it’s guided by what’s legislatively required. As much as we’d like to do lots of different things, it comes down to the politics of the day. What are the goals of that particular party in power?” She asks.

“How much power do you have to actually make a difference?”

Dr Carter now works at the The Behaviour Change Collaborative, a social enterprise working to increase community engagement with projects such as Greening Australia’s Our Park Our Place. The project, which aims to engage and educate communities in disadvantaged suburbs lacking trees, holds tree-planting events across Perth.

Greening Australia and their partners – The Behaviour Change Collaborative and three Perth councils – are connecting with local communities to retrofit greenspace together. Video: Ashleigh Davis.

Greening Australia senior project officer Ruth Cripps says even though they have planted about 40,000 seedlings throughout the project, their overall goal was more about getting communities involved.

“It’s about increasing canopy cover in the suburbs but also looking at that social dynamic – how do we do that by understanding community attitudes and behaviour as well?” she says.

“When you look at the average local government area, around 40 per cent is residential or privately owned land. So it’s important we can talk to residents and help them understand how they can make their home gardens more sustainable, even if it just means adding in a street tree, those are really powerful ways we can have an impact.

“The park itself, although we’re trying to make parks better, it’s really a tool for us to engage with the community.”

Even with the dizzying urgency of climate change action and the rate of environment degradation that weighs heavily on many shoulders, remarkably, individuals can make a positive change. Everyone has the power to positively effect their quality of life and the value of their neighbourhood by planting more trees.

Associate Professor at the University of Western Australia Dr Bryan Boruff was part of a team that worked alongside the CSIRO to map Perth’s urban vegetation. His research investigating the impact of tree canopy cover on socio-economic status and wellbeing, informed the 202020 Vision Where Should All The Trees Go? report.

According to Dr Boruff, developers aren’t entirely to blame. He says state government policies have historically failed to properly protect trees from both large-scale developments and infill development. He says though there may be an appetite for more environmentally conscious development and urban planning, without strong state policies, developers are likely to continue going with the cheapest option.

Interestingly, Business News recently reported “a number of developers are questioning the wisdom of the clear-felled, cookie-cutter template”, possibly signalling a changing tide in housing development.

Infill development – which includes subdivisions, urban sprawl, and a reduction in private garden space – is also a major contributor to canopy loss. The WA Government has a 47 per cent urban infill target by 2031, encouraging denser living within the Perth metropolitan area.

Development is on the rise around Perth. This may come as little shock considering the stimulus packages being put into building and construction – including the WA government’s $20,000 building bonus.

The City of Kwinana alone has approved 437 new buildings in 2021, the majority of which will create more lots on the ground in new growth suburbs. In response to how new developments will affect the council’s green space, City of Kwinana CEO Wayne Jack says the Local Planning Policies adopted in 2016 require developers to install at least one street tree per lot and has guidelines for retaining “vegetation and mature trees within road reserves and … new public open space.”

“[The policies have] been successful in ensuring that trees are considered early in the subdivision design process, and more trees are retained,” he says.

The City of Kwinana reversed its previous trend of green cover decline and had one of the highest growths in green cover in Australia between 2016-2020. Mr Jack says the council managed to put around 22,000 plants in the ground this past financial year with the help of over 900 volunteers.

Perth’s suburbs by temperature and canopy coverage. Data: CSIRO

Though the State Government is largely responsible for urban planning requirements, these policies are enforced by local councils. Councils then in turn have their own plans, goals, policies, and schemes. Though many local WA councils now have goals to either retain or improve canopy cover, when it comes to development, there is no minimum requirement across-the-board for the retention of tree canopy.

Urban planner and research project officer at Royal Melbourne Institute of Technology (RMIT) Thami Croeser is part of an international urban greening advisory team for the European Union.

He says managing urban greening is a large task for local councils to manage.

“Right now, the big player is your local council … Local governments are the guys that own the footpaths, that look after the [verge] trees, and they also set the rules on what you can do on your private property, which is where we’ve lost so much.

“They’re quite small organisations that are carrying out these tasks,” he says.

Unfortunately, planning approvals go through well before construction takes place, so visible changes are not immediate. New developments are likely to have been approved before the new guidelines came into effect.

The Behaviour Change Collaborative’s Dr Carter says it remains to be seen whether new policies will be more effective at maintaining and encouraging green space and tree canopy cover.

“What we know is, it will depend on how it’s implemented. Like all of these things. Things can be written, but it will be up to the developers in many ways, just see how they choose to work with it,” she says.

“At face value, looking at what they’ve done with the new guidelines, it’s much stronger and much clearer in all of those issues around environment. So I’m hoping that in translation, we will see some better things happening.”

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