The trees are cutting a stark image against the skyline, as they have been since landscaping work around the root structure left them susceptible to attack from fungal pathogens.
The state of the trees became an issue in 2010, when a $50,000 programme was launched to rehabilitate them. At that time there was a concern all the trees, which were more than 100 years old, would die.
The Ministry of Agriculture and Forestry investigated and found no sign of primary pathogens, but said the trees appeared susceptible to secondary pathogens, a weakness that could be due to their urban environment.
Last year two trees were removed.
Asked about their bare state this week, parks and recreation acting group manager Tom Dyer said the rehabilitation programme was "ongoing" and was helping restore key elements to the soil to help nurse the trees back to health.
