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The endangered forest

They are our lungs. But our native forests are facing a range of deadly threats, including kauri dieback, myrtle rust and rising deer numbers. Andrea Vance and Iain McGregor report.

On the very edge of New Zealand stands a forest of memories. Ancient ko pi trees, carved with symbols of meaning and depictions of long-dead Moriori ancestors, have stood long after the stories are forgotten.

But the trees are dying, another blow to the island people who have already lost much of their history and culture. Since the 1940s, more than 1000 rakau momori have been lost, with the remnants fading away. The loss of mature kopi is the result of land clearance for pastoral farming, the impacts of grazing and browsing animals, wind exposure and storm events.

Many of the surviving dendroglyphs stand in the Rotorua kopi grove on Kaingaroa Station, on the north end of Rekohu (Chatham Islands). It is a private reserve – fenced off to protect the remaining trees.

The kopi stand straight and tall, unlike the native akeake, which have bent and twisted in the island’s brutal maritime winds. Their dense canopy absorbs the gales, creating a silence in the groves.

They were once home to entire communities. Kopi (or karaka) were introduced to the island and cultivated for berries and nuts, which became a vital carbohydrate in the Moriori diet.

‘‘This is one of the old living spaces,’’ says Moriori rangata matua (elder) Tom Lenauze. ‘‘People actually lived in here and up in the dunes. That’s where the old people are, interned or where they are buried. It is a very sacred area to Moriori.’’

The kopi groves provided shelter – and were in turn protected by the broadleaf forest that once surrounded it.

‘‘On their own, they’re quite exposed,’’ says Tony Blackett, chief executive of the Hokotehi Moriori Trust. ‘‘Reforestation is critical for the survival of the kopi.’’

The trust established Recloaking Rekohu, a project to restore native forest to the island, creating a reserve 13 years ago. Other measures include pest control, increasing soil fertility, and the planting of wind shelters.

A 2010 study, by the Department of Conservation and Otago University, used laser scanning to assess the deterioration of the ancient carvings. The following year, the trust began removing the dying trees for conservation. They are treated and conserved at Kopinga (grove of kopi) Marae with a plan to eventually display them in a Whare Taonga [museum].

‘‘When they start to die, the bark actually comes off the tree. And we lose the rakau momori,’’ Blackett says.

Lenauze’s daughter, Loretta Lenauze, is t’chieki marae, guardian of the marae. While the historical loss of the rakau momori is heartbreaking, the trust is helping people to re-learn the lost art.

The carvings – which are actually bruisings that don’t penetrate the bark – feature stylised human images, fish, birds, seaweed, seals.

It’s part of a revitalisation of the Moriori, who were almost wiped out and saw their land, culture and language vanish.

‘‘It’s really important that we take steps to preserve what we have, and also make things better,’’ she says. ‘‘It’s extremely important to have great ecosystems and to look after what we do have.’’

Resurrecting the chiefs of the forest

When Maori arrived in New Zealand, the islands were almost completely shrouded in lush, dense forest. In Maori mythology, the god Tane Mahuta created both humans and forests, binding the two forever. They hold spiritual value, but also provided food, medicine and wood for fire and building. As more people arrived, the forests were burned and cleared for settlements and farmland, and slow-growing natives were felled for building and fencing. Logging of native forest on public land continued into the 1980s.

Globally, forests are hanging by a thread, with a recent report revealing 30 per cent of the world’s nearly 60,000 tree species are at risk of extinction. Between 1996 and 2018, New Zealand lost an estimated 44,800ha of indigenous forests, scrub and shrublands. As well as deforestation, taonga species now face the threat of diseases like myrtle rust and kauri dieback.

Myrtle rust, first identified in 2017, spreads on the wind, ravaging 37 species in the myrtle family, including pohutukawa, rata and manuka, and scientists have foreshadowed localised extinctions.

‘‘When they start to die, the bark comes off the tree. And we lose the ra¯kau momori.’’

The microscopic fungus-like organism Phytophthora agathidicida was discovered in a stand of kauri near Piha, in 2006, and the disease now known as kauri dieback was formally identified two years later. Humans and browsing animals spread contaminated

soil. Delicate root systems succumb when trampled, or are weakened by drought.

For more than 1000 years, Aunt Agatha has reached for the skies above Te Wao Nui a Tiriwa, the 16,000ha Great Forest of Tiriwa, which blankets the Waita kere ranges. Its columnlike trunk still stands solidly, but the spreading crown is now naked of leaves, blanched skeleton-like branches stark against the green canopy.

‘‘Unfortunately, Aunt Agatha now is dying. Kauri take a long time to grow and a long time to live. They also die slowly. This rangatira has fallen,’’ says Edward Ashby, of local iwi Te Kawerau a Maki.

‘‘It is heartbreaking for us, for our ngahere [forest]. That’s a real testament to how awful we’ve been doing a job of looking after the place. If your biggest, strongest, tallest member of the forest family is sick, that sends a very strong message that something’s not right, and that you have to do something about it.’’

In 2017, at the foot of Aunt Agatha, the iwi called down a rahui (customary prohibition or closure) on the forest. It works with scientists from Auckland Council, Landcare Research, Scion and the Ministry for Primary Industries to stop the spread of kauri dieback.

Since July 2018, a Natural Environment Targeted Rate was included in residential property rates across the city and is expected to raise $311 million over 10 years. More than $100m was ringfenced to manage kauri dieback and myrtle rust.

There are also innovations such as a trial to train two kauri dieback detector dogs. They’ll be deployed to sniff out the fungus on footwear, vehicles and equipment.

And there have been trials with phosphite, a fungicide used in horticulture.

In February, trampers were welcomed back onto the O manawanui Track and Puriri Ridge Track, on the Hillary Trail, which were carefully upgraded with specially-mixed gravel, thousands of steps, and hundreds of metres of boardwalk. The Department of Conservation also installed cleaning stations on tracks for boots and other hiking gear.

‘‘We needed to make the tracks safe in terms of not spreading soil, and also build them in a way that allows the kauri root systems, damaged by foot traffic, to heal,’’ says Stu Leighton, an Auckland Council park ranger, who has patrolled the forest for 20 years.

‘‘More and more people were walking this track, because it is stunning. But they didn’t want to walk where it was really muddy and slippery, choosing to go wider, so the footprint of damage was getting bigger and bigger.’’

By building boardwalks, trampers were lifted from the ground.

Lisa Tolich, Auckland Council kauri dieback team manager, says kauri are a ‘‘keystone species’’ for the forests they inhabit. ‘‘When we talk about kauri, we tend to talk about an entire ecosystem, because that’s what they support.’’

She says we have less than 4 per cent of mature kauri left. Fossil evidence suggests they once grew as far south as Invercargill, but now only exist north of Kawhia.

Some West Auckland residents opposed the closure of the tracks, and have questioned the authority of the rahui. Some have also ignored track closure signs.

Ashby has no truck with the critics. ‘‘Our old people say the environment knows how to heal itself if you just get people out of the way.

‘‘Kawerau have, for the last 150-plus years, had to watch others come in and trash our whare, our house. Come in with their dirty boots, chop down our ngahere, burn it.

‘‘We’re responding because we’re responsible kaitiaki. [I] don’t care if I never get to walk in this ngahere. So be it. As long as it’s here for tomorrow and for the generations that follow. That’s what’s important.’’

A re-emerging threat

Like disease, pests do not respect our human boundaries. Deer were first brought to New Zealand in the late 19th century for sport, and by the 1960s the populations were out of control.

Government culling and commercial hunting dramatically reduced numbers, but in

recent years they have rebuilt.

They are no longer confined to the back country, moving into areas where they have never been seen or were long absent.

For Sir Alan Mark, emeritus professor at Otago University’s Department Of Botany, their return threatens entire forests.

Mark led a vegetation study in Mt Aspiring Park in the late 1960s that laid bare the damage done by herds of deer.

His photographic survey – which continued until 2007 – coincided with the commercial hunting boom, and he was able to chart the regeneration of the forest. ‘‘The results were nothing short of spectacular. The forest

went from bare to a situation where you couldn’t really show the marker stakes because the growth of the beech regeneration was just so continuous.’’

Now, however, monitoring shows deer numbers increased by 34 per cent in the North Island and 21 per cent in the South Island in the last six years.

A national cull would be expensive, and likely ineffective. Now DOC is working with iwi, conservation groups and hunters to design a plan to manage wild deer, currently focused on the central North Island.

Ashby says we devote too few resources to protecting our forests. ‘‘Our forests are . . .

nationally significant infrastructure. We’ll spend $600m on a road so we can move trucks full of potato chips from Auckland to Whanga rei, but we put $1m, if we’re lucky, into our forest.

‘‘These are the . . . lungs of our city. If we don’t look after something as critical as essentially the thing that cloaks the earth, and life, and we give it less than 1 per cent of what we do to a motorway,0what does that say about us? The conversation has got to change.’’

In Depth

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2021-10-27T07:00:00.0000000Z

2021-10-27T07:00:00.0000000Z

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