Concerned residents packed out St Mary's Church hall on Bramall Lane for the Sheffield Tree Action Groups' forum.
They heard from some of the best in the business about the care and ownership of the city's trees.
Today's speakers included Russell Horsey, who is a former deputy director at the Institute of Chartered Foresters.
BBC Countryfile regular contributor, Rob McBride, was also at the conference, as was leading arboriocultural consultant Jeremy Barrell.
Mr Horsey travelled some distance to be at the conference, driving to Sheffield from Wales that morning.
Sheffield's Professor Ian Rotherham, who is an internationally renowned ecologist, spoke.
Audience members quizzed the presenters in Q and A sessions following the presentations.
Organiser David Dillner said he was thrilled with the amount of people who packed into the hall at the start of the conference at 11am.
"I'm deliriously happy," he said.
"It's a fantastic turnout with some superb speakers. There is lots of excellent information for the people who came today to take away."