Toward urban forest diversity: resident tolerance for mixtures of tree species within streets

Municipalities are setting targets for increasing street tree species diversity to support resilience and enhance the supply of ecosystem services from the urban forest. Assessments of street tree composition and structure, and consequent vulnerability to the stresses of urban climate change, pests, and disease, offer guidance for such targets. However, assessing local resident preferences toward species diversity within streets is also important to achieving such targets. Much of the research on street tree preference to date has focused on resident preferences for individual street tree characteristics, without reference to collective/contextual characteristics such as species diversity. We inferred resident preferences for collective street tree features, including species richness, from nearby house sale prices in the city of Brisbane, Australia. While home-buyers were willing to pay a premium for houses on streets with mature and aged trees, their tolerance for mixtures of species was limited to no more than six species nearby. Tolerance also varied within the city with greater sensitivity to mixtures of species in locations of greater socio-economic advantage. These findings suggest that increased diversity will not automatically be accepted by the community. Municipalities need to be cautious in their approach to increasing tree species diversity at finer scales, like streetscapes, within the urban forest.