Patterns of tree removal and canopy change on public and private land in the City of Melbourne

Abstract

Many cities face a struggle to reconcile ambitious tree canopy cover targets with urban development pressures. Canopy cover in The City of Melbourne, Australia, which has a target of 40 % canopy cover on public land by 2040, was analysed together with individual tree removal data, with particular focus on how many street trees were removed near major development sites between 2008 and 2017.We observed major gains and losses of canopy, resulting in small net changes.Our analyses showed a net gain in tree canopy cover in public streets and a net loss of canopy cover in public parks and private properties. The most frequently removed trees in both public parks and streets were small (<15 cm stem diameter). In contrast, more large, exotic trees were removed from public parks than public streetscapes. These large park trees represented a small proportion of total tree removals, but had larger stem basal areas and therefore large canopies. From 2008 to 2017, almost 2000 street trees were removed within 10 m of major development sites, equivalent to almost 20 % of all street trees removed in that time period, but this constituted only 8% of streetscape tree canopy cover losses.These findings suggest that in The City of Melbourne, mature tree succession and removal in parks has the greatest potential to hinder the achievement of canopy cover targets. Canopy cover gains could be maximised through improvements in the establishment and survival of replacement trees in both parks and streetscapes. The protection of the existing urban forest, through policy and practice, will also be critical for the retention and enhancement of tree canopy cover.