Streetscape noise attenuation by tree canopy and ground vegetation cover in Toronto, Canada

摘要

Environmental noise is a growing problem in urban centres. With a growing population and increasing proximity of residential areas to other land uses, large cities may fail to offer quiet spaces and peacefulness to its residents. Various studies demonstrate the effect of vegetation on noise attenuation. However, there is a lack of understanding of the magnitude of this effect in urban environments. This study investigated the relationship between tree canopy, ground cover vegetation and modelled traffic noise effects on observed daytime and nighttime noise levels. The analyses compared the effects of tree canopy cover, grass and shrubs in residential and mixed use zoning areas throughout the City of Toronto, Canada. Overall, the results showed a significant and strong effect of tree canopy cover in mixed use areas (e.g., residential-commercial) and a significant effect of vegetation ground cover in both land use categories. Specifically, in mixed use areas we observed a reduction of nighttime noise levels by 2.45, 3.02 and 4.34 dBA for receptors with <25%, 25-50% and 50% or more tree canopy cover within 50 m, respectively. We also observed a 3.00 dBA reduction for receptors with 50% or more tree canopy within 50 m in residential areas. Stronger attenuation by ground cover vegetation in residential areas may have confounded the effect of tree canopy cover, but the results nonetheless demonstrate the benefit of increasing tree canopy cover in mixed use areas where higher noise levels are generally also observed.