Three gates and some fencing on the route running through the Glion Gill plantation area, above Little London, have been damaged.
The land is owned by the Forestry Division. and is used by a tenant farmer.
It's open to the public for walking and bicycles, but not motor vehicles. Officers think the damage was caused by a four-wheel drive.
If you have any information, you can call Peel police on 842208.
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