“This is a transitioning forest,” Christo Mills explains, as we meander through celery-top pine and sassafras, man ferns, myrtle and fagus. Towering above are mammoth stringybarks – Eucalyptus delegatensis – the last guard of the eucalypt forest that has stood here for millennia. The eucalypts are gradually dying out, watchmen spaced further and further apart. In 50 years or so, enough of the remaining stringybarks will have crashed into the understorey that it will be reclassified as wholly rainforest. Long-fallen trunks harbour constellations of psychotropic-looking fungi: coral-like, caterpillar-furred, some that look like eyes, others like tongues of bright orange flame.

The path we’re following was once the fast track to Camp Florentine, a front line for one of the most fought-over forests in Australia.

“This was the escape run,” Dave Bretz says, padding ahead in flip-flops, his boots forgotten in Hobart, nevertheless darting over marshy ground now and then at the wink of a discarded drink can or to retrieve a snarl of paper from a fern.

“Fuckers,” he says, pocketing the litter.

It’s been several years since Christo and Dave called this swath of forest home, but the sense of custodianship abides. Last year they were employed as track builders to establish a path for tourists through their former camp site. Sections of the track are constructed of pine salvaged from nearby clearfells, where logging gouged out over 60 hectares of forest, leaving behind gigantic piles of celery-top pine – dense, oily, resistant to rot.

“It makes sense to use endemic materials,” says Christo. “And here were these mountains of beautiful timber left to waste.”

The distant growl of an engine finds its way through the ancient trees – incongruous, even this little way into the forest – and Christo and Dave look instinctively in the direction of the Gordon River Road.

“It’s so weird being back here and hearing cars go by,” explains Dave. “Just the old instinct to go, ‘Everyone shut up. Are they slowing down? Does it sound like a massive redneck engine? Who’s got a whistle?’ ”

Christo echoes that lingering disquiet: “When we were working out here, a local cop stopped because he’d heard that the walking track was going in. I was out the front having a coffee, and I was just shaking so much, even though it was six years since I’d gone through that.”

One of Christo’s more harrowing altercations with police was recalled for Anna Krien’s Into the Woods: The Battle for Tasmania’s Forests. Krien details Christo’s six-hour resistance to the “heavy persuasion” that left him with a broken nose.

Passing the local pub, featured in the film adaptation of Julia Leigh’s The Hunter, Dave asks if I remember the scene in which Willem Dafoe is threatened by hostile locals. “Those were our hostile locals,” he tells me. “Girls would go in to pick up a slab, get surrounded. One night we went in and there was just dead silence, then as we were leaving this old fella calls out: ‘Hope it rains and pisses all over ya.’ ”

“But when we were living and working out here last year, we actually made friends with people,” Christo adds, optimistically. “And it was once we stopped locking ourselves in the house.”

“Once we put on high-vis,” Dave clarifies. “We didn’t talk about being ex-blockaders, that’s for sure.”

They tell stories together, riffing off one another, even-handed in their piss-taking. It’s easy to imagine how this anecdotal rapport, the effort towards a complete vision, might correspond to the job: negotiating a subtle elevation here, sturdier edgework there, coursing to encourage a little runoff now and then. Working on the Twisted Sister track became the catalyst for establishing their own company, Track Work Solutions. Their first job was upgrading the track to Junee Caves, the deepest cave system in Australia and home to nightmarishly large cave spiders.

When I stop to admire a section of retaining wall, Christo offers the origin of every stone.

“Quartzite, sandstone, limestone, dolerite. That’s World Heritage rock, it comes from up higher; this one came from a residential wall that somebody had dumped in the middle of the bush; this one, we picked up at the side of the road. That one’s salvaged from a clearfell.”

The sidestep from forest activist to trailblazer came to seem an obvious career trajectory, blockading life having engendered the fortitude for such work.

“We were used to being wet, cold, working in miserable conditions,” Christo says. “Being up all night, preparing an action: rigging up cables or digging a car in, then having to lock on and face angry loggers – you learn to overcome fatigue and discomfort.”

Other protesters from Camp Florentine days are perturbed about tracks being built, adamant the forest, now protected, should be left alone.

“Some people thought that our tree-sits and lock-ons were going to stop loggers,” Christo says. “It doesn’t stop people; it slows them down, draws attention.”

Protesters who believe that operations can be stopped indefinitely by locking onto machinery tend to be more susceptible to emotional fallout, Christo says. He’s sympathetic to that level of battle fatigue.

“When you’re blockading, so often you’ll see this absolutely pristine forest, amazing. A week later it’s gone, hectares and hectares cleared by logging. It does play a cost on your mental wellbeing, seeing these beautiful places just… taken away.”

The comparative longevity of track building is part of its allure – being employed to imagine and implement access to such places, the lived-in knowledge and appreciation for the natural world recognisable in design and construct. Dave emphasises making the path just wide enough that people don’t stray from it – speaking literally, though it serves just as well in the figurative.

“You want people to come into this place,” stresses Christo. “Because then they realise: this is what the bush is like, this is why people risk themselves to preserve it.”