Trees in Jamaica Plain and around the city have been damaged in recent weeks by wood thieves who hack off large knobs known as burls. A Dorchester man was arrested Oct. 3 in the Fenway on burl-stealing charges, but officials are warning residents to stay alert to any suspicious tree-cutting.

Burls are abnormal growths that may contain a complex, attractive wood grain pattern that is highly valuable for art objects and other luxury goods. City parks officials have noticed burl thefts this year in Franklin Park and other parks around the city.

A historic oak tree on the Arborway at Dunning Street was hit twice, most recently on the night of Oct. 2, according to local residents. The second burl-cutting severely damaged the tree and revealed rot inside it.

Resident Susan Porter said she saw the burl thieves at work on the tree. She described them as two men, one with gray hair and the other younger, with a maroon pickup truck. They were teaming up to cut the burl off with a handsaw.

“They were working feverishly, sawing on the tree,” Porter said. “They just butchered the tree.”

“I know a lot of people are struggling now job-wise,” Porter said of the economics of burl-stealing, “but that’s such a dumb thing to do.”

The Arborway is controlled by the state Department of Conservation and Recreation (DCR), which is examining the local parkways for any further tree damage, according to spokesperson SJ Port.

The tree at Dunning Street is over 100 years old and severely damaged, said Port. She said DCR is evaluating whether it can be saved. She noted that any replacement tree almost certainly would not grow so large and stately in today’s harsh street environment.

According to the Boston Parks and Recreation Department, burl thieves have also used chainsaws and even worn orange safety vests like legitimate landscapers. Residents who see anyone cutting a tree in a suspicious manner should contact Boston Police at 911. Any damage discovered after the fact can be reported to the Mayor’s Hotline at 617-635-4500.