An Urban Forest Effects (UFORE) model study of the integrated effects of vegetation on local air pollution in the Western Suburbs of Perth, WA

Managing vegetation in urban environments requires an understanding of its structure, atmospheric interactions and function. This has led to quantification and development of models to estimate the functions of urban vegetation, particularly the integrated effects that take place between vegetation and local atmospheres. The Urban FORest Effects (UFORE) model (developed in North America by the U.S Forest Service (USFS)) provides a method of quantifying multiple functions of urban vegetation including the structure, deposition of air pollutants, emission of biogenic volatile organic compounds (BVOCs), carbon store and annual carbon sequestration, and identifies those species which are most effective at improving local air quality. It has had limited international applications and has not been applied to an Australian environment. This study applied UFORE to the vegetation on public owned land contained in several western suburbs of Perth, Western Australia. Differences in vegetation and air quality between Australia and North America were analysed to assess the applicability of this model to an urban Australian environment. There are many complex processes involved in both the removal of pollutants from the local atmosphere and the emission of BVOCs, which are currently unknown or difficult to model (such as dispersion of pollutants at different scales, physiological differences in vegetation between climatic regions and the effect of resource limitations on plant growth). However the results of this study provide a first approximation of the influence vegetation has on a local urban atmosphere in Western Australia. The results show an overall net removal of air pollutants (294 tonnes annually) when compared to BVOC emissions (119 tonnes annually). It is recognised that individual air pollutants vary in structure and reactivity, and there can also be significant spatial variability in the removal of pollutants by vegetation, hence this should be taken into account when planning the location of new vegetation establishments. While the Perth region does not yet have significant air quality issues, this analysis provides a greater understanding of how vegetation selection can impact local air quality and identifies the potential for UFORE to influence public planning and policy. Incorporating the atmospheric function of vegetation into planning early can ensure that the species composition and level of vegetation in the area will provide the maximum atmospheric benefits as the population grows and pollutant emissions increase In addition to traditional air pollution abatement strategies, vegetation can contribute to the air quality of local urban atmospheres, and is seen as a relatively cost effective method of reducing pollutant levels. Identification and incorporation of local data into UFORE will allow estimates of urban vegetation functions to be improved and lead to wider use of the model in Australian urban environments.