Deforestation. It is a word that conjures up mental images of loggers cleaving their way through pristine woodlands and grim statistics measuring how many football pitches worth of Amazon jungle get cleared every minute, but it isn’t something that only happens in the wild.
Trees in the city are also being chopped down, a fact that is of increasing concern to urban planners as it becomes apparent that tree canopies serve as much more than a decorative backdrop for the lives of residents.
Research indicates so-called “urban forests” also ameliorate localised water and air pollution (although this is contested), deliver measurable health benefits [pdf], provide shade, act as an air conditioner, and serve as a carbon sink to help mitigate the climate change that threatens to turn the world’s civic landscapes into concrete ovens.
If trees were to thrive in any Australian cityscape, it would have to be in the sprawling backyards of suburbia, but even here increased population density is thought to be placing pressure on tree numbers. The quintessential great Australian dream of a home on a quarter-acre block has made way for the dreams of enterprising developers, the green space of backyards replaced with ever-more housing.
Then there’s the room required for the infrastructure to service these higher-density cities: a need that has recently led to protesters chaining themselves to century-and-a-half old Moreton Bay figs standing in the path of the Sydney light rail, and to a collection of mourners tying black ribbons to the 70-plus trees in Adelaide’s Rundle Park before they were cleared to create space for a bus tunnel extension.
The decline in trees has sparked a range of interventions, from urban areas being included in Australian government plans to plant 20m trees by 2020 down to the local efforts of Brimbank City Council on the outskirts of Melbourne, which has mandated a minimum of two trees in the front yards of sub-divided blocks of land.
Another government project is the establishment in 2014 of the Clean Air and Urban Landscapes Hub (CAUL), a research consortium. One of the research group’s leaders is RMIT university senior lecturer Joe Hurley, who is examining the conflict between the redevelopment of cities and the provision of urban forests.