A council leader has promised to root out whoever has been deliberately poisoning historic trees.
More than ten trees, each centuries old, appear to have had holes drilled into them and a poison poured in.
The trees in the grounds of Koolunga House, near Addison Road in Gorleston, have not grown as many leaves as might be expected this year and upon inspection holes can be found near the roots.
Great Yarmouth Borough Council leader Graham Plant said it was difficult to understand what someone's motive could be.
Mr Plant added: 'It's a piece of woodland in the middle of Gorleston that's completely natural. Why would someone want to damage something as beautiful as that?'
Tree surgeons working for the council have assessed the tree and taken samples from near the top and now they are waiting for a lab for evaluation.
Mr Plant said if the borough council finds out who was responsible, they would seek to prosecute. The culprit could face an unlimited fine and even a prison sentence if charges were brought.
The historic Koolunga House was built in 1826 for a naval officer called John Garnham and was originally called Hill House and it once housed a historic grand garden.
The destruction of trees on private property is criminal damage and breaching a tree preservation order is an offence.
Anyone who cuts down, uproots or wilfully destroys a tree, or who lops, tops or wilfully damages it in a way that is likely to destroy it, is liable, if convicted in the magistrates' court, to a fine of up to £20,000.
If the person is committed for trial in the crown court, they are liable if convicted to an unlimited fine.
The courts have held that it is not necessary for a tree to be obliterated for it to be destroyed for the purposes of the law.
It is sufficient for the tree to have been rendered useless as an amenity.
The replacement tree is then subject to the same protection as the tree that was lost.
If the landowner fails to comply with this requirement, the local authority may serve a Tree Replacement Notice within a period of four years to ensure compliance.
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