Fencing at Stephens Castle in Verwood will need to be rewired after being deliberately cut in multiple places, putting planned conservation grazing at risk.
Dorset Council said the damage happened between Thursday 15 October and the morning of Friday 16 October, following other incidents in recent weeks.
The replacement fencing was installed after the previous timber fence deteriorated. It will allow grazing animals to help manage the heathland by controlling scrub and vegetation, reducing the need for heavy machinery.
The project is supported by Natural England, with livestock due to arrive shortly.
Councillor Jack Jeanes, Dorset Council’s Cabinet Member for Place Services, said: “Deliberate damage like this puts public money at risk, jeopardises important conservation work and could create serious safety issues once livestock are on site.”
The council warned that damaged fencing could allow animals to escape onto nearby roads. Gates and access points remain available for visitors, including dog walkers.
Dorset Police has been informed and additional patrols are planned.
Anyone with information can call 101 or email greenspaceseast@dorsetcouncil.gov.uk.
Photo: Dorset Council