2 days ago
Brisbane's shade cover falls short of targets ahead of 2032 Olympics
Brisbane's aims of becoming a city of tree shade to help alleviate urban heat islands in the lead up to the 2032 Olympics have gone backwards.
An internal council review, obtained exclusively by the ABC, warned that shade cover had "declined from 35 per cent to 32 per cent" in the ten years to 2019.
The reduction torpedoed council's ambitions set in 2017 for a "clean, green, sustainable" Brisbane with shade cover hitting 50 per cent in 2031 — the year before the Olympics and Paralympic Games take place in south-east Queensland.
"This is not currently expected to be achieved," the review, finished in May last year, warned.
The council in 2017 had plugged the program — which covers shading for footpaths and bikeways in residential areas — as part of a goal to "value, nurture and protect" the city's urban forest.
"Trees have a significant role in mitigating the urban heat island effect by reducing temperatures through shading and minimising stored heat," it said at the time.
Last year's review, obtained by the ABC via right to information laws, said that the 10-year reduction in shade level came despite "an average net gain of 5,243 trees [annually] in streets and parks".
"This decline is in part due to ongoing high levels of tree removals. Removing mature trees and replacing them with tube stock [young plants] or juveniles [sic]."
It said that council would aim to address the problem by planned maintenance programs and tighter controls over tree removals, including "alternative solutions", and recommended a tree planning project "to ensure targets are met".
Council did not answer queries from the ABC.
Ruby Michael, a senior lecturer in ecological engineering at Griffith University's Institute for Human and Environmental Resilience, said tree shade affected the walkability of cities, with areas lacking in shade less likely to have pedestrians and cyclists during hot times.
She said trees have a natural cooling effect as they transpire water from their leaves and absorb solar radiation, while road surfaces and buildings can radiate heat.
But she added tree benefits go beyond shade — they increase habitat and connections for wildlife in urban environments.
"We need to be providing for nature … in urban areas," she said.
The problems have emerged after the ABC this week also revealed that council's plans to keep hundreds of thousands of trees in good condition — thereby lessening the risk of damage to people or infrastructure — had fallen far short of targets.
