Sheffield Council has promised to give a rare butterfly the 'best possible' chance of moving to a new habitat once the tree where it lives is cut down.
The authority plans to fell the elm on the corner of Chelsea Road in Nether Edge as part of the Streets Ahead programme.
Campaigners have been fighting to save the tree, which is home to the white letter hairstreak butterfly - a species judge to be a priority by conservation bodies.
But the council says the old elm is 'decaying' and needs to come down as it is damaging the road and pavement. The authority claims it would cost about £50,000 to make the necessary repairs and retain the tree - although no cost breakdown has yet been provided.
Cabinet member for the environment Bryan Lodge said he was 'committed' to ensuring the white letter hairstreak could 'continue to inhabit and thrive on elm trees in Sheffield'.
The butterfly has been found on trees next to the elm due for felling, according to the council.
Coun Lodge added: “We are working on a mitigation plan for the butterfly, which will be discussed with experts in the field before a final plan is announced.
“Unfortunately, the elm tree on Chelsea Road has succumbed to severe decay over the years and this has been confirmed by two independent tree inspectors.
"We are looking at all available options to ensure the tree stands, in some form for now, to give the best possible chance of migration for the butterfly to a neighbouring tree or trees.
“The increasing safety concerns about this tree means that crown and tree reduction work may be required in the near future. However, we will ensure sufficient tree canopy is retained for the butterfly’s needs while that is judged necessary.
"No work will be undertaken on the tree for at least the next two weeks, whilst we explore all options.
“Ultimately, we are committed to ensuring the preservation of this rare butterfly colony and we will inform people of our final decisions upon receiving a final report.”
Campaigners say the elm is particularly rare, having survived Dutch elm disease, and should be retained because of its link to the butterfly.
The Independent Tree Panel, set up by the council, said it was a 'notable and rare species’ and there was a strong case to retain it.
And the elm was England’s runner-up in the Woodland Trust’s Tree of the Year contest last year.
The council says it will be replaced, with two further elms planted at the junction of Union Road and Chelsea Road. Hundreds of cuttings from the felled elm will be taken and planted across Sheffield over the coming years, the authority adds.