Tree Canopy Cover in Christchurch, New Zealand : report prepared for the Christchurch City Council

Abstract

Executive Summary: Tree canopy cover (TCC) is an important way of describing urban forests and is necessary to assess the ecosystem services they provide. Tree canopy cover was estimated for Christchurch, New Zealand using an object-based image analysis (OBIA) approach, supplemented with manual correction. The OBIA was based on aerial photography and LiDAR data acquired over Christchurch during the summer of 2015/2016. Tree canopy cover in Christchurch is 15.59%, ranging from a low of 7.15% in the Hornby ward to a high of 28.83% in the Coastal ward. TCC in land owned by the Christchurch City Council is 24.78%. TCC in road catchments is 10.97%, while TCC in parks and reserves is 28.73%. Significant proportions of the study area were identified for their potential as tree planting sites, signalling the possibility of increasing tree canopy cover in Christchurch. Future work could focus on minor refinements of the tree cover classification, using TCC to inform policy and management of Christchurch’s urban forest, defining a tree canopy cover goal for Christchurch, and regular monitoring of tree canopy cover changes.