This was published 9 months ago
Aerial images show the Brisbane suburbs where the landscape is changing
By Tony Moore
Brisbane tree cover – or lack thereof.Credit: Nine
Brisbane has more suburbs with good tree cover than any other state capital. But as an increasing number of people call south-east Queensland home, maintaining that coverage while also building the homes and infrastructure needed for a growing population is a key challenge.
Four years ago, researchers at RMIT found the Brisbane City Council area had 53.9 per cent “urban forest cover” – down 1.6 percentage points from 2016.
Brisbane has more suburbs with good tree cover than other state capitals.Credit: Tony Moore
The most recent assessment of Brisbane canopies was completed in 2021, showing 79 per cent of suburbs had more than 20 per cent tree cover, higher than Hobart (71 per cent), Darwin (66 per cent), Canberra (58 per cent), Greater Sydney (44 per cent), Melbourne (30 per cent), Adelaide (26 per cent), and Perth (22 per cent).
Urban planner Dr Tony Matthews, from Griffith University’s Cities Research Institute, said trees were needed to provide shade, clean air, and visual amenity.
“We have good green cover, but the issue is to prevent the loss,” Matthews said.
“This is one problem Brisbane is trying to manage. The other is intentional land clearing for greenfield residential development out in the suburbs, where everyone is on 350sq m blocks, so they are all built ‘gutter to gutter’ and there is no green space.”
What the aerial images show
Over the past 15 years, Nearmap has combined aerial photography with artificial intelligence to monitor tree species, moisture, building types and soil as cities evolve.
“Trees impact liveability in so many ways,” said Nearmap’s vice president of AI, Dr Michael Bewley.
Upper Kedron, where new housing estates have become established – along with the trees.Credit: Nearmap
“They take the edge off the hottest days substantially, they provide mental health benefits, and they encourage people to get out and walk about.”
In Brisbane, the biggest gains in tree cover between 2019 and 2023 were in Upper Kedron and Newstead. The biggest losses were in Pallara and McDowall.
At Upper Kedron, where almost 1000 homes have been built since 2014, the tree coverage increased from 35 per cent in 2019 to 45 per cent in 2023, while the percentage of buildings rose from 9 per cent of land to 10 per cent.
Bewley said it was an example of how well-chosen and carefully planned trees could replace the “few sapling streets” on site.
“It’s a real art form, and plenty of local governments are now getting good at this: thinking about which species goes where and how soil is available to grow them,” he said.
At Newstead, developers have long-term plans for new apartment towers, with outdoor spaces included in their projects.Credit: Nearmap
At older Newstead, the increase in tree canopy comes off a much lower base – from 6 per cent to 8 per cent – while the urban area increased from 32 per cent to 35 per cent.
Bewley puts it down to the age of the developments and their outdoor areas.
“There are just quite a number of trees that have grown considerably larger in that timeframe,” he said.
Pallara is the epicentre of greenfield development in south-east Queensland.Credit: Nearmap
But the loss of tree cover is most pronounced at Pallara, where small farms have been replaced by residential estates. There, the urban area has increased from 5 per cent to 14 per cent at the expense of tree canopy (35 per cent down to 30 per cent).
“They [houses] go up, very, very, quickly, and then there is that delay as you wait, hopefully, for the trees to grow,” Bewley said.
“Pallara looks like a classic example of a new build going in.”
Between 2019 and 2023, McDowall, in Brisbane’s northern suburbs, lost trees as it gained housing.Credit: Nearmap
In McDowall, on Brisbane’s northside, tree cover has dropped from 22 per cent to 20 per cent, while the urban area has increased from 22 per cent to 23 per cent.
“McDowall lost a large number of trees, and you can see it’s through a process of new builds,” Bewley said.
While people concentrated on cities, he said, “each suburb is a fascinating story in its own right”.
“From new housing developments to urban infill, to little saplings that are nurtured to grow into larger trees. Individual suburbs can have an impact on the overall story.”
The plan for the future
The South-East Queensland Regional Plan outlines how the urban footprint will expand by 5000 hectares to allow 900,000 new homes, units and townhouses for another 2.2 million people by 2046.
Regional biodiversity corridors in the 2023 South-East Queensland Regional Plan.Credit: Queensland Government
The planning document features “regional biodiversity corridors” meant to be protected from development. There are also tree-cover targets for councils to create more shade, reduce the heat-island effect and improve air quality.
Councils must achieve a minimum of 15 per cent tree cover in the city centre, 25 per cent in urban residential areas and commercial areas, and 50 per cent in suburban residential areas.
Brisbane City Council says it has about 45 per cent tree cover across the city, and its City Plan offers added protection to significant landscape trees and sensitive habitats.
Councils will ultimately decide how to accommodate more people in their area, with input from planners, developers, residents and the state government.
This article was produced in collaboration with the Australian Science Media Centre, with support from the Walkley Foundation-administered Meta Public Interest Journalism Fund.
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