The Tree Council's chairman, Sean Freeman, said it would make a submission opposing the consent.
"... we only have 6000 listed trees and these few special trees are supposed to have the highest level of protection possible. During the public hearings for the unitary plan, senior planners from Auckland Council described the trees on the scheduled list as 'the best of the best across the city'."
The absence of recorded historical heritage connections for the two magnolias "is irrelevant to their place on the schedule list and the level of protection that conveys".
Nor should "desired views or vistas of a fountain/monument negate the protection of a scheduled tree".
Heritage was just one of five criteria under which trees had been put on the protected list. The others were age and health, character and form, size, and visual contribution, Freeman said.
He said up to 70 trees had already been removed from the vicinity of the park entrance without the public being given a say.
The trust board's plans involve removal of 10 other magnolias, but Cornwall Park director Michael Ayrton said they would be replanted elsewhere in the park.
"When the work is completed the area will have more trees in total, with extensive native planting, including rare plants that you will not be able to see in any other part of Auckland."
Seventy-five puriri, totara and kohekohe were being planted.
"The reduction of trees around the gateway area proper will be offset by a double-row, tree-lined alley around Campbell Crescent that will tie in visually to the grand trees along Puriri Drive."
"The landscaping will reinstate the original sightlines to the fountain and statue and allow for greater access into the park."
Ayrton said that as well as planting, pruning and removing plants, the project involved upgrading the Campbell monument and the installation of new paths, seating and amenities.
"The cost of this work is confidential to the trust, but obviously does not involve any public expenditure and is consistent with honouring the legacy of Sir John."
Campbell gave the park to New Zealand and running it is funded by the trust board's resources, also provided by Campbell.
The Auckland Council said that if submissions were received on the application to remove the two notable magnolias, a public hearing would be held, most likely in late-November.