Bushfire ends 15-month Australia tree-sit protest

Miranda Gibson, 31, took to a makeshift platform atop a eucalypt tree in Tasmania in December 2011 and has remained there since, demanding that the state's high conservation value forests are protected from logging.

But advice from her support crew that an uncontrolled bushfire was only a few kilometres away and posed a risk convinced her to abseil down.

"Any change of wind could bring it this way quite rapidly, quicker than I'd have time to escape," she told reporters.

"That was basically the reason for having to make this hard decision but obviously I have to prioritise safety and not put myself or anyone else at risk."

She said she would monitor the situation and decide whether to return, with the campaign continuing at ground level until then.

While up the tree, she used cutting-edge technology to blog, Skype and Facebook as spokeswoman for the green group "Still Wild Still Threatened."

Environmentalists say her tree-sit was Australia's longest, beating the 208 days Manfred Stephens set in north Queensland in 1995.

An emotional Gibson, a school-teacher, said there were highlights like watching wedge-tailed eagles soar by, but also tough times.

"Over winter obviously (there were) difficult weather conditions to get through and the isolation, missing my friends and family, was always a consideration," she said.

"They're the challenges I was willing to sacrifice and to accept in order to do this for the forest."