Hobart engineer Alex Wylie took the position on Thursday following the arrest of two other tree sitters in the Sumac region over the past week.

Bob Brown Foundation campaign manager Jenny Weber said Mr Wylie was "tree-sitting in these ancient forests to defend them from imminent logging".

"The occupied tree is situated where Sus Timbers Tasmania plans to bulldoze a new 1km road for logging," she said.

"These unique ancient forests will end up as woodchips and timber for the contentious Malaysian logging giant Ta Ann, they need to be left standing for climate benefits from intact forests and for the wildlife that depends on the forests for their homes.

"Premier Hodgman can save taxpayers funds by immediately halting plans to log these forests and provide secure protection for takayna / Tarkine."

Officer in Charge of the Burnie Police Division, Inspector Adrian Shadbolt, on Tuesday urged Tasmanians to consider how they protest following the arrest of 21-year-old Andy Szollosi.

"While the protester (Mr Szollosi) elected to leave his tree-sit location shortly before police traversed up to him - the attendance for our expertly trained rescue officers diverted their capacity to attend to someone who could have been in need of an emergency rescue at the time," Inspector Shadbolt said.

The Bob Brown Foundation said it was successfully defending the ancient forests of the Tarkine "with another group of Tarkine Defenders".

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