Rare plant colonies in Derbyshire are being ruined by mountain bikers, according the Forestry Commission. Riders are being warned by foresters they could be prosecuted if they continue to cycle at Shining Cliff wood near Ambergate.
There are reports that riders have been digging and moving stone to build bike tracks.
The commission says permanent damage could be done to the site, which is an area of Special Scientific Interest.
Fragile environment
Forester Albin Smith emphasised that riders need to stay away.
He said: "We want to appeal to their better nature to not come riding here as we provide facilities for mountain bikers in other parts of the district.
"Shining Cliff wood is not suitable for this sort of activity at all.
"It does not have a track network and it is a very fragile environment."