WAIPOUA FOREST, New Zealand — Two arborists, chest-deep in underbrush, secured a rope slung over a branch in the Waipoua Forest, close to the northern tip of New Zealand.

Scott Forrest pumped his fist. “Yeah, great stuff,” he said. He recently won the world championship for tree climbing.

But the job this day was a special privilege.

He was about to ascend a 148-foot-tall, 2,000-year-old kauri tree known as Tane Mahuta, a tree so sacred to the indigenous Maori people that even touching it is taboo.

The climb, carried out in late August, was a matter of urgency — and part of a growing collaboration among the local Maori tribe Te Roroa, arborists and researchers.

The goal is to prevent Tane Mahuta and other New Zealand kauri trees from succumbing to a deadly, fast-spreading rot called kauri dieback.

In preparation for the climb, the team disinfected all its gear and had it blessed by a Maori elder. The equipment included a spectroradiometer, which provides readings from the tree canopy to detect types of bark, leaves, lichen and habitats for forest animals. Later, these readings can be checked from a drone to monitor the ecosystem and its health.

“That would be extremely useful, considering how large our forest is,” said Taoho Patuawa, the Te Roroa’s science adviser.

Tane Mahuta — with a massive bone-colored trunk and crown of tangled branches — is named after the Maori god of the forest, who separates his earth mother and sky father from an embrace and thereby lets light into the world.

Early detection of kauri dieback is key. Once a tree shows visible symptoms, it is already doomed. This means a loss for the forest at large because the kauri is called a “foundation species” that shapes the ecosystem around it.

The disease is caused by a water mold, phytophthora, literally “plant destroyer,” which leaches plants of their nutrients and has wreaked havoc around the world.

In 1845, it ravaged Irish potato crops, causing a devastating famine. In California, it is responsible for the plague known as sudden oak death. It has destroyed heathlands in Britain and cash crops across Africa. And in Australia, where 40 percent of the country’s native plants are infected, it has been called a “biological bulldozer.”

Yet finding a way to battle the disease remains elusive.

The dieback was first reported in New Zealand in 1959. In the past decade, a unique strain of phytophthora has been identified as targeting kauri. Last year, it was detected only 100 feet from Tane Mahuta.

One pinhead-size speck of phytophthora can travel for miles on a boot only to dislodge in a new patch of soil, propel itself into a kauri root, then slowly eat its way in until nothing remains of the mammoth except a pale skeleton, said Conrad Marsh, a Te Roroa tourism ambassador, who assists and guides visitors at the Waipoua Forest.

Per Liljas with permission of Te Roroa

Generations ago, this would have been less of a problem. Robust ecosystems are less vulnerable to phytophthora, and the kauri forests of New Zealand’s north had been thriving since the time of the dinosaurs. However, European colonization led to more than 95 percent of kauri forests being logged or burned.

Last year, the International Union for Conservation of Nature downgraded to “threatened” the status of kauri — a species that little over a century ago was seen as so plentiful there were plans to make Australian streets with its logs.

“There’s an intergenerational sense of loss,” said Snow Tane, a top official for the Te Roroa.

The kauri is a treasure to his tribe, figuring abundantly in its songs, prayers, chants and proverbs — but over the past 150 years, the Te Roroa also saw their homes, holy sites and language slowly disappear.

In the early 1900s, some scholars believed neither kauri nor Maori would survive the century. Today, however, Maori language and customs are widespread, and decades of court battles have led several tribes to settle land disputes with the government. The Te Roroa regained ownership of the Waipoua Forest and neighboring tracts in 2007.

“Now we’re back and we need to protect our land,” Tane said.

Studies show New Zealand’s ecology is under pressure. A government-ordered report released in April says several rare ecosystems are on the brink of collapse.

Worries about kauri dieback had been growing among a group of academics, environmentalists and bureaucrats for a decade. The national response was widely viewed as inadequate, with little funding, scattered ownership and researchers burning out.

Then a study in 2017 showed that the pathogen had doubled its spread in Waitakere Ranges, a regional park in Auckland. This led the local tribe, Te Kawerau a Maki, to place a cultural prohibition on entering the forest. Outdoor enthusiasts went up in arms.

“The hikers should understand that we’re their landlords. We take a 100- or 1,000-year perspective, and right now this forest needs to rest,” said Robin Taua-Gordon, the tribe’s heritage and environment trust officer.

That has not yet been the decision in Waipoua Forest — even though motion-triggered cameras have shown several people walking up to kauri for hugs and selfies. (Ironically because they often want to show sympathy for the sick giants.)

The Te Roroa and the Conservation Department, in collaboration with scientists and arborists, have responded by renovating the boardwalk, beefing up the boot-cleaning station at the entrance and increasing the hours attended by tourist ambassadors.

The tribe is also replacing commercial plantations with native trees, and works closely with researchers, artists and educators to increase and spread knowledge about and interest in the forest.

“For us, it’s all about being a good ancestor,” science adviser Patuawa said. “That’s what we’re here to do, and that’s what we can do.”