A pinboard by
Camilo Ordóñez

Postdoctoral Research Fellow, The University of Melbourne


What happens to animals and people when trees are removed from urban green spaces

Urban trees can help solve many urban sustainability problems, including the effects of urbanization on nature and people, and climate change. While many cities have ambitious targets to plant more trees, many municipalities also spend millions of dollars removing trees every year. Large, old trees sometimes pose a hazard to human safety and hinder construction activities, and hence are often removed. Given that the services that trees provide are more significant as trees age and increase in size, when large trees are removed there is a rapid loss, absence, and slow recovery environmental services, such as shade and control of storm-water runoff. However, today there is no clear understanding of the biodiversity, psychological, and social effects of tree removal. This is because very few experimental studies focused on measuring these effects have been carried out. The team I lead is currently undertaking an innovative before-after-control-impact experimental investigation on the impact of tree loss on biodiversity and psycho-social parameters in the City of Melbourne. The study focused on the changes in animal behaviour and psycho-social processes. For this wee are tagging possums with radio collars and tracking people's movements as well as assessing their well-being, before and after trees are removed from selected sites. We would be thrilled to present our results at the first-ever World Urban Forest Forum so we can share our novel research with the global community in charge of tree-care and maintenance in cities. Our research could significantly improved the way urban trees are evaluated for their social and biodiversity services.


Increasing biodiversity in urban green spaces through simple vegetation interventions

Abstract: Cities are rapidly expanding world-wide and there is an increasing urgency to protect urban biodiversity, principally through the provision of suitable habitat, most of which is in urban green spaces. Despite this, clear guidelines of how to reverse biodiversity loss or increase it within a given urban green space is lacking.We examined the taxa- and species-specific responses of five taxonomically and functionally diverse animal groups to three key attributes of urban green space vegetation that drive habitat quality and can be manipulated over time: the density of large native trees, volume of understorey vegetation and percentage of native vegetation.Using multi-species occupancy-detection models, we found marked differences in the effect of these vegetation attributes on bats, birds, bees, beetles and bugs. At the taxa-level, increasing the volume of understorey vegetation and percentage of native vegetation had uniformly positive effects. We found 30–120% higher occupancy for bats, native birds, beetles and bugs with an increase in understorey volume from 10% to 30%, and 10–140% higher occupancy across all native taxa with an increase in the proportion of native vegetation from 10% to 30%. However, increasing the density of large native trees had a mostly neutral effect. At the species-specific level, the majority of native species responded strongly and positively to increasing understorey volume and native vegetation, whereas exotic bird species had a neutral response.Synthesis and applications. We found the probability of occupancy of most species examined was substantially reduced in urban green spaces with sparse understorey vegetation and few native plants. Our findings provide evidence that increasing understorey cover and native plantings in urban green spaces can improve biodiversity outcomes. Redressing the dominance of simplified and exotic vegetation present in urban landscapes with an increase in understorey vegetation volume and percentage of native vegetation will benefit a broad array of biodiversity.

Pub.: 23 Feb '17, Pinned: 16 Mar '18