Sydney and Melbourne have least tree cover of biggest Australian cities

http://www.theguardian.com/world/2014/jul/17/sydney-melbourne-least-tree-biggest-cities

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Tree cover in Sydney and Melbourne is lagging far behind Hobart, Brisbane and Darwin thanks to burgeoning development in Australia’s two largest cities, a report has found.

The study, conducted by the University of Technology Sydney, found that Hobart was the “greenest” capital city in the country, with 59% of the Tasmanian capital covered by tree canopies.

Brisbane, at 49%, and Darwin, at 28%, make up the top three cities. Melbourne and Sydney took out the bottom two positions, at 13% and 15% respectively.

In the first study of its kind, researchers measured the area covered by trees in each city using software which calculates the composition of urban areas from aerial images.

The software, called iTree, was used to analyse the make-up of 139 local government areas which comprise the more densely populated areas of Australia, containing 68% of the country’s population.

Overall, the average urban area contains 39% tree canopy cover, with just 8% made up of “hard surfaces” – buildings, footpaths, car parks and bodies of water. The rest is comprised of shrub area and sites cleared for development, pastures and lawns.

The report was commissioned by 202020 Vision – a group that aims to increase Australia’s urban green space by 20% by 2020.

Sydney and Melbourne came bottom of the list due to their rapid rate of development, while a relative lack of high-rise buildings in Hobart helped the city to the top of the pile.

“Some of the older, more established cities which haven’t been built up rapidly have the higher densities of tree cover,” Anthony Kachenko, of the National Urban Forest Alliance, told Guardian Australia. “Sydney and Melbourne are built-up cities with a lot of competition for space. They have to think more strategically about their green spaces.

“In Brisbane and Darwin, we’re seeing a high percentage of canopy cover to help cool the cities down. Australia is projected to warm in the future, so other areas may look to go down the same path, to use tree canopies to provide relief from the heat. Western Sydney is certainly an area that could look to do this.”

Local government areas with a high proportion of concrete rather than trees include Fremantle in Western Australia and Maribyrnong in Victoria.