Biodiverse cities or green light for biological invasions?

Abstract

Considerable effort and money are spent to promulgate greener, more biodiverse cities with a fundamental push to increase the green connectivity between remnant urban bushlands and with their surrounding natural habitats (ecological reserves and National Parks). Yet, cities are recognised as major point of entry for biological invasions and provide abundant shelter and food resources to sustain established populations of invasive species. An increased connectivity of green spaces across the cities could therefore create new hazards for the health and safety of native species and the human residents. In Australia, most greening strategies designed for large urban centres only consider invasive species as a secondary nuisance that can be managed a posteriori. Established pest populations are very difficult and costly to control unless the effort is invested at the early stage of invasion and lethal control of wildlife is often controversial in urban landscapes. A novel approach that has yet to be further explored consists of manipulating the habitat within the urban green spaces and corridors so as to maintain their functionality for biodiversity and their benefits for human residents while slowing the spread of invasive species. The key to success involves cross-disciplinary research between urban design, conservation and biosecurity.