Woodland near Loughborough have become a hot spot for anti-social behaviour, fly-tipping and criminal activity, wildlife officers have said.
They have found rubbish being dumped and bins set on fire in the Outwoods area.
Part of a dry-stone wall had been knocked down and the stones taken while flowers had also been dug up and taken.
Mark Graham, of Charnwood Borough Council, said those responsible had been very thoughtless.
'Couple of quid'
He said: "The volunteers have recently repaired a section of dry-stone wall that was knocked down.
"I think somebody tried to take a stone from the bottom and the whole wall fell over.
"It's just selfish behaviour at the end of the day really.
"It's just somebody who doesn't want to spend a couple of quid on a rock from a garden centre, who thinks 'oh I'll just take it off a wall' but it does belong to somebody and there are people who care about it."