The three dead plane trees in the Octagon will be cut to ground level as soon as practicable, the Dunedin City Council community and environment committee decided at its meeting in Municipal Chambers yesterday.
Cr Lee Vandervis asked if anything had been learned about the consequences of damaging root systems.
The trees were damaged during the construction of retaining walls.
Council group parks manager Mick Reece gave an ''absolute assurance'' there had.
''The work in the Octagon at the time caused a number of people real concern and lessons had been learned,'' he said.
Of the three dead trees, two of them were planted 130 years ago and the other was a semi mature tree planted about three years ago, a committee report said.
Mr Reece said the roots were damaged during the ''over ambitious'' transplant and the tree never recovered.
''The engine room below the ground never caught up with the demands from above. It's a physiological failure.''
Mr Reece said several large trees were transplanted successfully in Dunedin but every transplant depended on the level of ''care, preparation and money'' available.
Another two trees identified as in decline, opposite the Dunedin Public Art Gallery, would continue to be part of a health treatment programme designed to help the stand recover from a fungal disease that swept through the trees a few years ago.