Council contractors cut down trees in Sheffield city centre at 6am on Sunday after more than 3,000 people signed a petition calling for them to be saved.
Amey carried out work on four trees in Fitzalan Square as part of a multi-million pound scheme to improve public spaces in the city centre.
But campaigners claimed the trees were 'healthy and mature' and were the last mature trees in Sheffield city centre.
Graham Wroe, who submitted the 3,189-strong petition to Sheffield Council said: "They came like thieves in the night, as they were aware that they were doing this without the consent of people in Sheffield.
"The city centre is now totally bereft of mature trees that soak up particulates, improving our air quality, giving us shade in hot weather and soak up water to help prevent flooding when it pours.
"They will be replaced with new trees but I can't find any mention in the council documents of the species. I fear they will be smaller trees not capable of the eco services the plane trees offered, especially hosting many birds that used to cheer up our city centre.
"It is so sad that our council do not value trees. It is ironic that one thing they are making room for in the Square is air quality monitoring equipment. Without the trees the air quality will be far worse."
The council said it would be replacing the four trees with 12 new ones.
Speaking about the plans in March, Coun Mazher Iqbal, Cabinet Member for Business and Investment, said: “We have been able to secure £4.1 million for this project. The reason for removing the trees is because the buses couldn’t turn if they were there. “The tree roots are also damaging the pavements so regardless of this scheme, we would have had to do something.”