Kauri die-back is killing our forest giants from Bay of Plenty to the Far North. The fungal disease is creeping ever closer to the oldest, most majestic trees like Tane Mahuta in Northland's Waipoua Forest. For their kaitiaki, Te Roroa - it's a constant worry - and a heartbreak.

Photo: Supplied

It's been many years since Snow Tane climbed a kauri.

But he can still show you the spike marks in the trunks of trees he climbed to gather seed for the government nursery.

The general manager of the Te Roroa Trust began his career in Waipoua Forest in the days when it was managed by the Forest Service.

Photo: RNZ / Lois Williams

The small iwi was affirmed as kaitiaki of its ancestral forest through its 2008 Treaty settlement.

And though the kauri sanctuary is still part of the Conservation estate, Te Roroa has its headquarters in the kauri sanctuary.

These days, it's Snow Tane's mission to protect the rakau rangatira - the noble trees - from all human contact. Tree huggers included.

There've been signs of kauri dieback - phytophthera agathdicida - in Waipoua for decades.

Photo: RNZ /Lois Williams

But in recent years, the soil-borne pathogen has tightened its grip on the forest and trees have died just a few hundred metres away from the oldest and most famous trees, including Tane Mahuta.

The majestic tree, and others, which predates the birth of Christ seem so far unaffected.

But Snow Tane says the kaitiaki are worried.

"You drive through the forest, on that state highway - and you see a dead kauri every twenty seconds or so. There's heaps."

The Te Roroa chairman Sonny Nesbitt says the iwi doesn't know if the disease is spreading, as it is in the Waitakere's.

"We are not getting the answers from DOC or science... I'm not sure if it's getting worse, or we are just finding more sick trees.

"It's heartbreaking. It's like, we are the forest, and the forest is us ... there is a spiritual side to this as well as the physical."

DOC's northern region manager Sue Reid-Thomas says DOC does not know how many trees are affected by kauri dieback in Waipoua or whether the disease is spreading.

"I haven't got any good data on that. I would say that we continue to identify trees showing symptoms; MPI did some aerial surveys last year and we have to follow up on that data."

Although an aerial survey of the forest canopy was done in 2011, there was no follow-up "ground-truthing" work - that is, no ground teams were sent in to locate the trees and soil test for the pathogen.

Photo: RNZ / Lois Williams

It's a different story in the Waitakere Ranges Regional Park, where that work has been done.

The Auckland council has been able to compare data from the 2011 surveys, and the 2016 ones and confirm that kauri dieback infections have more than doubled in the past five years.

The sick or dead trees are mostly close to walking tracks - although there is also a correlation with waterways and the bait-lines used by pest controllers.

Dr Nick Waipara, who's been researching kauri dieback for a decade, says the results are distressing.

"We closed areas of the Waitakere ranges to protect healthy kauri, and we're seeing people using closed tracks. On one track - 5000 people, determined that they knew best," he says.

Photo: RNZ / Lois Williams

"Now they are going to be vectoring that disease further into that healthy stand."

Dr Waipara says there has been a gradual decline in the effectiveness of the kauri dieback management programme.

He says there are important areas of research that have not been funded, and he's critical of MPI's management of the programme as the lead agency.

"We still don't know for instance, exactly what we're dealing with; we don't even know if the disinfectant DOC is using in foot cleaning stations, actually kills the spores. We know it disrupts them at a certain point but if it doesn't kill them people can be carrying them on their boots or whatever, for years."

MPI says decisions about research funding and disease prevention measures have been made collectively by the programme governance group that includes DOC, iwi and council's from Bay of Plenty to Northland.

Photo: RNZ / Lois Williams

Its pest management spokesman, John Sanson, says Aucklanders should take heart from the fact that kauri dieback has not made the jump to the Hunua ranges.

But Nick Waipara says unless the programmes amped up - and quickly - Auckland stands to lose entire catchments of the trees.

Dr Peter de Lange, DOC's former principal science advisor for 27 years, has a darker prediction.

He warns that kauri are heading for extinction.

"I can tell you now that (based on the Waitakere park data) kauri is now being listed as a threatened species. This is an iconic tree and we are potentially going to lose it."

Back in Waipoua forest, Snow Tane's gentle demeanour changes to one of frustration, when a bus driver tells him a 100 tourists from a Korean meditation centre have just headed into the sanctuary for a spot of mass mindfulness.

They've had to use DOC's state-of-the-art foot cleaning station to get onto the track. But Mr Tane is horrified.

"They're not supposed to be in there like that unless DOC knows about it, but they (DOC) are thin on the ground and how do we know this lot will stick to the boardwalks?" he says.

It's vital that they do.

Phytopthera travels in soil - and it's easily transported on footwear or tyres.

Once one tree's infected, its neighbours are also at risk: the spores infect roots and kauri roots not only entwine they also fuse, 'Avatar'-style, underground.

Coming down the track a long line of happy meditators files past - led by a local tour operator who Snow Tane says does not have a franchise for this sort of visit.

That's what the iwi is up against, he says.

That and freedom campers, who try to park up at night in the many little lay-bys on the road that bisects Waipoua kauri forest, and then wander in amongst the big trees - without any shoe-cleaning or supervision.

Photo: RNZ / Lois Williams

"It's a huge worry," Snow Tane says.

"Last year was a major problem. Our teams found human waste in every lay-by ... this forest is at risk now from the spread of kauri dieback and by the middle of summer the freedom campers will be everywhere. That's the biggest risk."

Te Roroa employs security guards who patrol the road and try to move the campers on.

Snow Tane says some resist.

"I found one chap, he was French and he'd gone into the forest and set himself up very nicely for the night, with a campfire and everything. Another guy, he was a kiwi - he told me it was public land and he had every right to be there."

He says the Te Roroa patrols try to educate the campers, but they have no legal power to make them go.

The iwi's worst nightmare, he says, is that Tane Mahuta or one of the other taonga trees will become sick.

Chair Sonny Nesbitt says if that happened the iwi might consider a rahui, like the one Te Kawerau a Maki is imposing on the Waitakere forests - asking people to stay out.

Phosphite injections, which scientists are using in trials on kauri in nearby Trounson Park, could also be a weapon of last resort.

But he says the iwi fears for the future of its ancestral ngahere and wonders what to do for the best.

"What does the research say? We're not getting anything back from the research except mitigation measures like Trigene (shoe-cleaning disinfectant) and still no answers but 'here's a mitigation process so we can still go ahead and collect the tourism dollars.'"

DOC says its policy is to treat every kauri in Waipoua as if it were infected or at risk, and it's spent millions of dollars improving the tracks in the sanctuary, making them dry and safe.

Sue Reid Thomas says she'll be talking to Te Roroa about their concerns, and may be able to give them delegated powers to move those freedom campers on.

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