About 63 trees would have to be cleared to build the first stage of the Australian War Memorial's half a billion dollar expansion.
An early works application shows parts of the planned expansion of the underground car park are not consistent with the war memorial's heritage plan.
But the memorial says it's done what it can to minimise any impact and plans to replace lost trees with natives more suited to the local area.
The application, lodged with the National Capital Authority, is to expand the basement car park next to Poppy's Cafe for visitors.
It would also create a temporary car park above the basement to cater for workers during the larger development works, which are expected to last about nine years.
The car-park expansion is the first stage in the ambitious, and controversial, plans to expand the war memorial. The half a billion dollar redevelopment would see a complete redesign of the memorial's lower ground floor and a new underground exhibition hall to display large items such as helicopters and jet fighters.
The proposed basement car park extension would provide 123 parking spaces on site to accommodate for the expected increase in visitors.
The temporary contractors' car park above would include 115 car parks.
The report said 63 trees would need to be cleared to complete the works.
Once all development works at the memorial are complete, the temporary car park would be converted back to an open landscaped area, with new trees planted.
It is estimated the car-park expansion will cost $10.8 million.
A heritage impact statement said the works were expected to have a moderate impact- especially in the medium term - on the war memorial's "aesthetic characteristics".
But it said the landscape to be created on the temporary car park site - once work on the war memorial is complete and the workers' car park no longer needed - would mitigate the longer term impact.
The report said the plans were "not fully consistent" with some policies in the war memorial and Parliament House Vista heritage management plans.
"In all cases, the long term re-creation of an informal landscape character with native trees mitigates the impacts, although the trees in the re-created landscape will not be as tall when mature compared to current mature plantings," the report read.
"Related to these impacts, the works will also be not consistent or not fully consistent, especially in the medium term, with all relevant policies and actions in the heritage management plans."
It suggested considering whether the design could be reviewed to keep more mature trees.
The memorial should also look into temporary landscaping measures on the upper car park level to help screen the exposed car park area from view, the heritage report said.
A memorial spokesman said it conducted a public consultation session in July, but despite significant a letter box drop to surrounding suburbs very little interest was shown by the public, with 11 people attending the three hour session.
He said by the end of the project, when the contractors' car park is re-landscaped, the area would be more suited to the natural environment than it is now.
"At the completion of the project, the temporary car park ... will be returned to a native landscape environment and enhanced by the planting of local species of trees and plants more amenable to ACT wildlife," the spokesman said.