Auckland's trees vulnerable to housing intensification
Auckland's trees have little protection against urban intensification and of those that are left, only a few are listed for preservation, a new study has found.
The research, by Senior Lecturer Dr Margaret Stanley and Research Fellow Dr Sarah Wyse from the School of Biological Sciences at the University of Auckland, found the Auckland isthmus has just six percent of urban forest left.
Of that, well over half (63 percent) is on private land where just 15 percent of trees are protected through Auckland Council's Schedule of Notable Trees. The Schedule is the only remaining tool for tree protection after changes to the Resource Management Act in 2012.
The study found the spread of protected trees across the city was highly uneven, with older suburbs having relatively high numbers of protected trees while other areas had very few.
The range of protected trees on the Schedule was skewed towards more popular species while a threatened species native to Auckland, tawapou, was represented by just a single specimen.
Along with providing food and habitat for native birds and insects, trees contribute significantly to the wellbeing of city residents but relying on the Schedule alone to protect them may not enough, Dr Stanley says.
"Given the housing challenges Auckland faces and calls for housing intensification, further pressure is likely on the remaining urban forest in Auckland and individual trees," Dr Stanley says.
The study also found plenty of weeds on the protected list such as Phoenix palm (Phoenix canariensis), radiata pine (Pinus radiata) and camphor laurel tree (Cinnamomum camphora).
Some trees on the Schedule were also listed under Auckland Council's Regional Pest Management Strategy.
"The study shows the Schedule is failing to adequately protect unique native tree species and we need to do much better if we are to protect what is left of the city's urban forest," Dr Wyse says.
The study used a light detection system called LiDAR which creates a topographical map from GIS data. The system works by using remote sensing satellite technology to measure distance and height through reflected light. The latest data layer for Auckland dated 2008 was used in the study, which mapped tree cover within the old Auckland City Council boundaries.
Auckland does have special ecological areas where significant vegetation cover is protected but these areas represent just 5.5 percent of the Auckland urban area.