Cool Communities—Urban Density, Trees, and Health

Abstract

A move towards more compact and climate-resilient cities is being encouraged around the world. As part of these plans, there is a need to manage the potential conflict between increasing urban densities and the extent of tree canopy in cities. Reductions in tree canopy are a major contributor to the urban heat island (UHI) effect, which will act to reduce rather than increase climate resilience in many cities. A systems thinking approach called Collaborative Conceptual Modelling was used to study the interaction between urban infill, tree canopy, and human health in Perth, Australia. The results indicated that under current planning policies and development practices, the behaviour of the system is dominated by the drive towards higher housing densities. While this may result in the attainment of urban infill targets, it is likely to lead to a reduction in tree canopy, higher temperatures, and a decrease in a range of other benefits provided by trees. Recommended actions to overcome this behaviour were determined by the identification of leverage points in the system. These included a shift to a sustainable development paradigm that places greater value on the environmental and social benefits provided by trees and a greater emphasis on a climate-resilient future. Market and legislative mechanisms should be integrated into the city’s greening strategy and development plans to ensure the protection of existing trees and the inclusion of new trees on public and private land.

SSI Analysis of Long-Term UHI Development Due To Urbanization Affecting Urban Ecosystem and Local Climate Change Through City of Izmir Case

“…Trees and vegetation in cities therefore play a vital role to mitigate the UHI effects especially by regulating high temperature in densely urbanized areas and surrounding city parts (Gillner et al, 2015). Thus, such actions with natural solutions are integral parts of struggling with UHIs (Brown et al, 2018) that shouldn't be overlooked since they ensure a sustainable urban development and enhance the quality of citizens' life and the environmental conditions at where the city inhabitants live (Riffat et al, 2016).…”

Role of Vegetation as a Mitigating Factor in the Urban Context

“…Numerous studies have analyzed the effects of vegetation and green areas on the microclimate of the city [173][174][175][176][177]. Although there are some conflicting data on the effect of vegetation on air temperature, in general, the presence of green areas is considered as a factor that has positive effects on decreasing the temperature in an urban environment thanks to the shading effect on urban surfaces and on buildings and also to evapotranspiration (evaporation from the soil and transpiration by plants) that reduces the transformation of incident solar radiation into sensible heat in favor of latent heat [117,147,152,172,[178][179][180]. Conversely, during winter, planting a barrier of windbreak species on the north side protects buildings from cold winds, reducing fuel consumption for heating.…”

Accommodating a tree asset register of street trees in a local government authority setting

“…Important tangible benefits of street trees include health impacts such as enhanced physical health through stress reduction and increased social cohesion and enhanced urban open space (de Vries, van Dillen, Groenewegen, andSpreeuwenberg, 2013, Klemm, Heusinkveld, Lenzholzer, Jacobs, andVan Hove, 2015;). Street trees also reduce heat islands and improve the thermal comfort (Brown, et al, 2014). In addition, street trees form intangible benefits such as cultural and regulating services, as illustrated in Figure 2.…”