An Environmental and Economic GIS Scenario-Based Analysis of Ecosystem Services Performed by Urban Trees in Ringwood and Greensborough, Melbourne, Australia

Josh Martin

The loss of vegetation cover within the urban landscape due to processes of urbanisation has lead to numerous biophysical hazards that are detrimental to the quality of the urban environment. Flash flooding, degraded air quality, raised air temperature, and decreased carbon storage and sequestration are four of the more prominent hazards encountered by urban communities. As the world’s population becomes increasingly urbanised, the need for thorough and strategic planning is paramount to successfully manage the urban environment in a sustainable manner. Urban foresters advocate that the practice of urban forestry provides a viable solution for the mitigation of biophysical hazards that occur as a result of urbanisation. Despite this, state government urban planning policy for Melbourne (Australia) neglects to include any policy initiatives relating to the protection or enhancement of tree cover within the urban landscape.

The aim of the honours research project was to quantify the environmental and economic benefits of urban tree cover in Melbourne for the present and future context. CITYgreen, a GIS-based urban ecosystem modeling program, was used to asses and compare the environmental and economic benefits of urban trees for two Principal Activity Centres (PACs), Greensborough and Ringwood. These two PACs have contrasting approaches to the management of vegetation within the urban landscape. Comparisons were made between three urban landscape scenarios: (i) present landscape configuration; (ii) predicted landscape configuration for the year 2030; and (iii) extensive tree cover landscape configuration.

The results of this study clearly demonstrated that increasing vegetation cover within Melbourne’s landscape is highly likely to lead to a substantial improvement in the health of Melbourne’s biophysical environment. Modelled benefits included an improvement in air quality, a reduction in peak stormwater runoff flows and an increase in the carbon storage and sequestration. Conversely, a decrease in vegetation cover is likely to have the opposite effect with increase peak runoff flows, degraded air quality and reduced carbon storage and sequestration. Revegetation strategies such as that currently being undertaken within the Greenborough activity centre offer a practical approach to maintaining Melbourne’s reputation as one of the world’s most livable cities. This study illustrated that the incorporation of urban forestry into urban planning policy for Melbourne has the potential to guide sustainable urban development by helping policy makers and urban planners make informed decisions regarding the planning and management of urban vegetation.

Prof Jason Beringer and Dr Shobhit Chandra