CITY ratepayers will foot a $100,000 bill for moving a single tree from Victoria Square to the south parklands.

It will be the second move for the 14m tall pink Kurrajong within six years, after the Transport Department shifted it within the square to make way for the tram extension to North Tce in 2007.

A council spokeswoman said the 80-year-old tree was classed as "regulated", meaning it had a circumference of more than 2m, and was therefore "worthy of relocating".

The move comes as the council fends off criticism for its decision to raze 27 trees in Rundle Mall and replace them with 48 Chinese elms, as part of a $30 million upgrade.

Asked to explain the cost of the latest move, a spokeswoman said it was "related to ensuring the tree receives the very best in tree care".

"A crane and slings will be used, an excavation hole needs to be created for the tree's new position and we have engaged an expert arborist to assist in the relocation," she said.

In 2007, a 140-tonne crane was used to move the tree 15m east, after 100 tonnes of soil was excavated around it.

Its entire 6m wide root ball was dug out with the tree and transplanted into an 8m wide hole. An irrigation system was also installed.

The council will plant 87 lemon scented gums as part of the Victoria Square project.

None of the other 48 trees to be felled are regulated and so will not be replanted.

Mr Yarwood said the Kurrajong was the "oldest and most substantial" tree affected by the works.

"It was moved when the tramline was done," he said.

"It would have been highly inappropriate to cut that one down."

However, he said the high cost to ratepayers was "a difficult issue" to which "there's no right or wrong answer".

Adelaide Parklands Preservation Association president Ian Gilfillan said the expense was "silly" because "the integrity of a tree is really in its location".

"This is a silly sop to people to say 'we care about trees'," he said.

Mr Gilfillan said he was left "speechless" by the council's plan to raze almost 50 mature trees in the square.

Mr Yarwood said the lemon scented gums would provide a uniform appearance across the square and a "stunning canopy" for shade.

The $100,000 cost will come from the Stage One budget, which will run to millions more than the original $24 million in order to complete the central plaza and deal with soil contamination.

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