The States say private wood collectors have been ignoring the barriers and cutting logs from felled trees.
Six days after Storm Goretti the clear up continues, with a lot of effort concentrated on the Castel parish, where the Talbot Valley and Le Guet suffered badly.
Barriers were put across the entrance to Le Guet, above Cobo, to stop people clambering around the fallen trees and possibly hurting themselves.
But the States say that some people, armed with chainsaws, are getting around them and into the pine woods to saw logs.
The message is do not endanger yourself nor the tree surgeons who are working to clear the damage.
Most of Guernsey's major roads are free of tree debris although the Talbot Valley is not scheduled to reopen for a few more days.
Work is turning to minor routes where the onus may be on the landowner to arrange for trees to be cut up.
Traffic and Highways is asking private landowners to update them regularly on the work, and when the roads become clear.
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Fallen trees in Guernsey could be in the 'low thousands' following Storm Goretti
