Tassie tree-sitter undeterred by bushfire TASMANIAN tree-sitter Miranda Gibson is vowing she won't be deterred after it was found a bushfire that forced her to end her protest was deliberately lit. Police are investigating the fire which caused Ms Gibson to end her 449-day "Observer Tree" anti-logging protest in southern Tasmania's Tyenna Valley. An investigation by Forestry Tasmania found the fires were deliberately lit and police are appealing to the public for information about suspicious activity. It is potentially the second attack on the 31-year-old after she was one of the protesters assaulted in a car in the Upper Florentine Valley in 2008. The sledge-hammer attack resulted in a secret video being viewed globally on the internet and the conviction of three forest workers. Ms Gibson is undecided about whether to return to the tree-sit but says she will continue her campaigns. "It's important that the police investigate this because it's an absolutely serious issue if people are attempting to cause harm to peaceful protesters," she told AAP. Obviously I am not going to let instances like this deter me. When we faced assault by those logging contractors ... I did not let that deter me from continuing this fight. Ms Gibson said violence on the "forest wars" front line was a rarity. "That occurrence a few years back in the car was a challenging incident and does show that there is instances of violence out there," she said. I haven't found it to be the normal occurrence. Ms Gibson said she had no reason to believe she was being targeted and, despite her prolific social media presence, had received no threats. "There are suggestions around that there are various Facebook pages out there that are not supportive of environmentalists and may include threatening comments," she said. In terms of directly contacting me personally through Facebook, I never really had any problems with that sort of thing. Detective Constable Craig Fry said police were still speaking to people who'd been in the area but no witnesses had yet come forward. He declined to comment on the force's view of Ms Gibson's protest.