Kauri dieback: Nearly three years since Waitākere Ranges rāhui, what's changed?

Wednesday, 9 September 2020

Waitākere ranges tracks are slowly re-opening.

The fight against a fatal, incurable disease in Auckland’s biggest kauri forest is far from over, nearly three years after a regional park was closed to stop its spread.

Auckland Council biosecurity manager of kauri dieback Lisa Tolich said the complete re-opening of the Waitākere Ranges in West Auckland could take years and there isn’t a specific timeframe for when it will occur.

Local iwi Te Karewau ā Maki imposed a rāhui, or ritual ban, to stop access into the forest in December 2017. The forested areas of the ranges were officially closed off by the council in May 2018.

More than half of the tracks in the ranges have been closed since 2018, to stop the spread of kauri dieback.

The move was in response to the spread of kauri dieback disease, a microscopic fungus-like organism called Phytophthora agathidicida.

**READ MORE:

Auckland Biosecurity manager of kauri dieback, Lisa Tolich says they can’t put a timeframe as to when the forest can completely re-open.

* Closed tracks in Waitākere Ranges Regional Park to reopen over next five years

* Slow progress on upgrading tracks as fight against kauri dieback continues

* Council moves to close Waitākere Ranges and Hunua kauri areas

The disease starves kauri trees off nutrients and water, effectively starving it to death.

It is spread through soil, infects roots and starves a tree of nutrients and water.

A 2017 council study found the disease had spread extensively – nearly a quarter of trees in the 2571 hectare kauri forest were infected or possibly infected.

More than half of the ranges’ 112 tracks were closed and behind the scenes, studies and research began to understand the pathogen and find a way to save the kauri for generations to come.

Tolich said for now, the council is taking a precautionary approach when dealing with kauri dieback.

The lag time between disease spread and observable symptoms is still unknown but the council is in a better place now with what it knows about the disease than it was two years ago, she said.

Cleaning stations have been installed in open tracks to help reduce the spread of disease by people.

The natural environment targeted rate tax, initiated in 2018, has provided much-needed capital to fund the work on kauri, including track upgrades.

However, any possible date for reopening the whole of the ranges is unknown, she said.

“It will take us having a far better handle and understanding of the disease and how we can combat it, how we can either reduce the impact of its effects or manage the further spread of that disease to non-diseased areas.

“If we can get a far better handle on an effective approach to doing that then that would be a whole other situation, and we’ve always said we are operating in an adaptive management approach.”

A second five-year survey of the forest expected to get underway this summer will help towards this, she said.

Like Covid-19

Senior ranger Stu Leighton says there are parts of the forest that are diseased now, which weren’t in that condition two years ago.

Tolich said it can be difficult for people to understand why it’s taking this long to find solutions, years after the council enforced the closure.

The council’s precautionary approach towards the disease can be likened to the Government’s fight against Covid-19, she said.

“Every time we are wearing masks or asked to lock down for a period of time, it doesn’t necessarily mean we know everything about the disease, it doesn’t necessarily mean we have a vaccine that can do all of these things but it’s one thing we know we can do to have an impact.

“We’re a little bit still in that space from a kauri dieback perspective. We are probably further along than we are with Covid … the reality of science is that it can take that long to get a handle on these things.”

Tolich said for now, the council is managing risks and prioritising track upgrades, which is the only way to get people back into the forest.

“We’re buying time, it could be in 20 years we know a lot more, could be in five years, could be two years – that would allow us to restore access to those trees.

“We weren’t here two years ago, so from that management intervention perspective, I think it’s great, but we still have a lot to do.”

Slowly, but surely

The track upgrade and re-opening programme is still on track despite the coronavirus lockdown.

So far 37 tracks are open and six partially open in the ranges. Nine more tracks are expected to open this summer.

The most diseased part of the ranges remain at Piha Valley and it is there that phosphite treatment is being tested on kauri trees. The effect of that remains to be seen.

Senior ranger Stu Leighton said there is a lot of work involved in re-opening a track, including considering the shape and features of the landscape, the water in the area and the proximity to infected trees.

“As we are putting in the infrastructure, we’re making sure we’re thinking about future use, especially as numbers into the forest grows all the time,” he said.

“The more people we put in an area, the more the environmental impacts are.”

The devil is in the detail and Leighton’s team spends a lot of time looking at the type and size of gravel, nails, wood for boardwalks and even non-slip plastic mesh that can be used on a track.

“A lot of people think we just chuck gravel on but a lot of thought goes into it, where it comes from, even the size given different gradients in a track and things like that.

“Every time we do something, we always look to improve it. We aim to get it perfect but it’s a constant cycle of learning, being prepared to try stuff, it might work, it might not, we’ve never done this before.

“The ultimate test is getting hundreds and thousands of people walking across it and of course, the weather conditions.”