Approaches to urban vegetation management and the impacts on urban bird and bat assemblages

To balance the needs of people and biodiversity in cities, local governments are increasingly incorporating green spaces and urban greening initiatives into urban planning frameworks. Despite this, there is little information on which vegetation features or management actions are most useful in supporting biodiversity within these green spaces. We assess the effect of three vegetation management approaches that are commonly suggested to improve outcomes for urban biodiversity, including: (1) increasing the proportion of native vegetation; (2) increasing the density of trees, and (3) increasing the volume or complexity of understorey vegetation. We use a network of 39 urban green spaces (including golf courses, public parks and residential neighbourhoods) to assess how these vegetation management approaches impact urban bird and bat communities. The richness of both birds and bats increased with an increase in the proportion of native plants, bird species richness increased with increasing volume of understorey vegetation, and increasing large tree density led to increased bat activity. Our study suggests that increasing native vegetation composition and understorey vegetation volume, and the retention of large trees are practical vegetation management approaches that improve outcomes for urban birds and bats. Our data also suggests that as urbanisation and infill development proceeds, retention of large green spaces (such as golf courses) will be critical for urban biodiversity conservation, as these areas supported a component of the bird and bat fauna which was not recorded in other green space types.