Derbyshire Wildlife Trust has criticised proposals to develop part of Derby city centre.
There are fears the move would discourage wildlife
Cityscape plans to develop the city's Cathedral Green, which means including a new pedestrian bridge over the River Derwent and a landscaped area.
It will be partly financed by around £1.5m from the government's "growth point" funding.
Nick Brown from the Wildlife Trust said he was worried that the move would discourage wildlife from the city.
Movement of people
He said: "This is a green oasis. It's not going to be 'Cathedral Green' any longer it's going to be 'Cathedral grey'.
"I am very concerned that this part of the city, which to me is quiet, has a lot of wildlife and could have a lot more wildlife, is going to be destroyed."
Chief Executive John Cadwallader of Cityscape said the development would be good news for Derby residents.
He said: "It is important to join the northern part of the city to the northern side of the river.
"It will help the movement of people around the city and help to create the right ambience for people to go and sit and be entertained.
"We've been in consultation for about four or five weeks now on our projects and generally we're getting a favourable view."
Derby is one of 45 "growth point" towns and cities across England to receive a share of £40m to improve the local infrastructure.
Construction on the development should start early next year.