A project undertaken at Western Sydney University, and supervised by Dr Manuel Esperon-Rodriguez.
Urban forests provide multiple environmental and socio-economic services to citizens. These include heat mitigation, biodiversity conservation and social integration. Urban forests can also help citizens cope with psychological stress during events such as the COVID-19 pandemic. The delivery of these services, however, relies on healthy and thriving urban forests. Climate change threatens the health of urban forests and thus will impact the delivery of services.
Further, urban trees face harsh environmental conditions (e.g., droughts and heatwaves) exacerbated by urban heat islands, which cause dieback and reduced tree vitality. Therefore, the long-term stability of urban forests depends on the identification of species that are resilient to climate change.
For this, we need to understand how urban trees respond to environmental conditions by determining the climate sensitivity of urban tree growth and identifying vulnerable or resilient species to changes in climate. Studies of the effect of climate change on urban trees are rare and, to date, research on climate sensitivity of urban tree growth has been conducted at the local level, limiting broad assessments of species’ responses to climate.
This study aims to evaluate urban tree growth and performance by reconstructing growth histories and developing realised climate sensitivity indices of urban trees in Australian cities distributed along temperature and precipitation climatic gradients. We selected a common set of 10 resilient and vulnerable urban tree species based on bioclimatic modelling of risk of climate failure. We collected tree rings of street trees planted in seven Australian cities of contrasting climates to determine spatial and temporal patterns of tree growth in relation to climate extremes and test hypothesized differences between vulnerable and resilient species. Our results will guide species selection to maximise services delivered by urban trees under future climates and minimise environmental and socio-economic losses to governments and citizens.