A 100-year-old oak on Poole Borough Council's Whitecliff recreation ground has been targeted by people hoping to kill it off.
The tree was ring-barked, following several reports of trees at the site having branches removed.
The trees in the open space have been protected by Tree Preservation Orders because of the amount of vandalism.
Offenders risk a fine up to £20,000 in a magistrates court or unlimited in a crown court.
"We will always prosecute," said Poole Borough Council planning enforcement officer Andy Dearing. Since January 2007 there have been nine successful prosecutions, netting £21,950 in fines and costs and 17 formal cautions.
Anyone with information about damage to trees in Poole should contact planning enforcement officers Jane Stewart or Andy Dearing on 01202 633304.
Subscribe to Horticulture Week for more news, more in-depth features and more technical and market info.