Should we build our cities up or out? That’s the question we asked when we considered the challenge of how a growing city can retain its wildlife. While it’s unrealistic to believe city living can co-exist with a full complement of biodiversity, we wondered if there were differences in the impact of different growth strategies.
With half of the global population already living in cities, and predictions of increasing urban population in the future, this is far from an academic question. While the urbanisation that accompanies the movement of people into cities is one of most ecologically damaging and fastest-growing of any land use, little is known about how we should design the growth of our cities to minimise their ecological impact.
Australian cities are among the lowest density in the world. While this makes them liveable, being characterised by large backyards and leafy streets, it means that our cities take up a very large area for a given population size. Using the city of Brisbane as a case study, we asked whether a more compact type of urban growth, where new housing is concentrated within existing city borders, would be better for conservation.
Urban growth in Brisbane has historically been of a sprawling character with a very low density of houses. However, in the face of recent rapid population growth, the state government has adopted a...