Urban trees are significant because of the many important ecosystems services they provide such as: shading and cooling of walkways and buildings, biodiversity habitat and conservation, carbon sequestration, atmospheric pollution reduction and amelioration of the urban heat island effect. In addition, these trees can provide a ‘sense of place’ for local communities and city visitors. Certain tree species and plantings have strong cultural and heritage relevance, such as Plane tree boulevards and parkland Elm trees in Melbourne’s inner suburbs. Urban trees provide a connection for residents and office workers with ‘nature’ or ‘greenery’ within a grey landscape, which can improve mental health and well-being.
The urban forests of many Australian cities were established in the late 1800’s or early 1900’s and have reached or exceeded maturity. As such, local councils are having to remove and replace large numbers of street and parkland trees. This phase of replacement and renewal presents opportunities to reconsider plant selection in light of the ecosystem services we demand from our urban trees and their vulnerability to the soil and climatic conditions within our towns and cities. A great deal of the urban tree research with GIRG is focused towards better understanding and quantifying the ecosystem services provided such as: shade, human thermal comfort, biodiversity habitat, stormwater reductions; as well as the physiological thresholds of trees to heat, drought and future climatic extremes.