'The skin of the taniwha'

Thursday, 18 August 2022

The sky gets bigger at Kopuatai. Out in the middle, surrounded by low-growing rushes, ringed in the distance by hills, you’re maybe a couple of kilometres from the nearest dry land, further if you head north or south.

Seen from above, there are some brilliant green spots – umbrella ferns – but the rest is a tawny colour, appearing for all the world like wind-swept tussock.

Underfoot, it’s wet, even in the middle of summer. In winter, you’re glad of the boardwalk towards the centre.

**READ MORE:

* Uncounted and unseen, is this the biggest planet warmer you've never heard of?

* Nature will be the loser in unfair hearing on Plimmerton Farm development

* Wellington's hidden carbon sink could remove equivalent of 110 cars permanently

**

This is the Kopuatai dome in Waikato, up to 15,000 years of slow-growing peat bog, rising by a millimetre a year, a couple of metres higher at its centre than its perimeter, and a highly effective carbon sink.

Near the centre stands an atmosphere measuring station, a slender white tower about 6m high, guy-roped for support, with aerial-style contraptions at its top, vanishingly small in the immensity of the bog.

A few metres back along the boardwalk, are a couple of deckchairs.

At this time of year, the ground is seriously wet and it takes the researchers, including Waikato University associate professor Dave Campbell about an hour to slog out there. “We step up on the boardwalk, pull the deck chairs out and sit down, have a coffee to plan what we're doing,” he says.

“And then you just relax and you look around and go, ‘wow, we're the only people that get to work out here. How lucky are we?’ It's like being in a rainforest, I guess. You can't see any dairy cows. You can't see the pasture.”

And, he says, the sky is big.

What is at the feet of Campbell and his fellow researchers is extraordinary. It’s as if the bog breathes, rising in winter and falling again in summer.

This is an internationally significant wetland, one of three in Waikato along with Whangamarino and Firth of Thames. Unseen from the Hauraki Plains road, it survived the pumps and drains of Waikato’s ever-expanding farmland.

The plants here, predominantly low-growing wire rushes, are perfectly adapted to the low-nutrient, acidic conditions. Everything is effectively on the verge of starvation, Campbell says. “And then,” he says, “you start getting organic matter being preserved.”

New Zealand’s varied wetlands host an array of native species, from swamp orchids to bitterns and spotless crakes. There are specialist plants like the giant canerush, Sporadanthus ferrugineus, which in turn is home to the stem borer caterpillar dubbed “Fred the thread”. They can be places of beauty, particularly in the miniature, with the likes of dragonflies and carnivorous sundew plants to look out for.

But New Zealand has less than 10% of its original wetlands left. Draining for farmland has created an unforeseen cascade of consequences. For a start, the peat sinks at the rate of about 2cm a year. Hence power poles at crazy angles, and farm buildings gradually rising above their surrounds. Hence, also, a bid for about $9 million worth of government funding for an upgrade to Muggeridge’s pump station near Ngatea, where the land is partly below sea level, to allow dairy farming to continue.

The peat also burns; with the water table gone, the dry, fibrous material left behind is susceptible to fire and can burn for weeks.

But wetlands are also highly effective flood controls, absorbing flows and then releasing them slowly. Similarly, they can be effective at filtering nutrients from runoff.

Nevertheless, dairying has thrived on all this reclaimed peatland, aided by drainage and pumps. So this land has also been an economic powerhouse.

The preserved organic matter Campbell refers to has a further, near-miraculous benefit; it locks in the carbon breathed in by the plants at the surface, eventually sinking, as new plants take their place, and forming peat several metres deep. Draining releases that locked-in carbon.

Dramatically.

Drained peatlands make up just 1 percent of New Zealand’s land area but, as knowledge rapidly advances, they are estimated to be responsible for 8 percent of our net carbon emissions annually. That’s not from the activity conducted on their surface. It’s not from the coal that has been mined beneath them. It’s from the carbon released by decomposition of the peat soil as oxygen gets in and aerobic microbes are unimpeded above the lowered water table. And there’s plenty more to go in Waikato – thousands of years’ worth of peat metres deep.

Campbell’s measurements of fluxes of gases, along with hydrology and other weather conditions at Kopuatai, meanwhile, indicate the jointed rush bog is a strong sink for greenhouse gases.

It’s hardly surprising attention is turning to rewetting – either by restoration or, following the European lead, wet farming, also known as paludiculture.

The water table beneath drained wetland fluctuates a metre and a half throughout the year. The Kopuatai water table fluctuates 15-20cm, thanks partly to the plants’ ability to conserve water and partly to the surface rising and falling, adjusting the amount of storage available for water.

It’s a highly stable natural system, looked at one way. But even scientists – especially scientists – are allowed flights of lyricism.

Kopuatai is a living organism, Campbell says. “It breathes. It's one big organism and it's breathing. In winter its surface goes up 20 or 30 centimetres and then in summer it goes down again. This is the product of living processes and the skin of it is the living ecosystem.

“Talk about Gaia hypothesis.”

He has a further, memorable flourish about that tawny rush-covered surface.

“I've called that the skin of the taniwha because that's how I think of Kopuatai. It's actually this living organism and this is the fur of the beast.”

Campbell fetches a slightly bent cylinder, fibrous and dry, from a shelf in his office. In the hand it’s rigid and tough but impossibly light, as if it could blow away in any passing gust. Imagine a core taken from a giant bird’s nest and you get something approximating it. It is a peat core from Kopuatai, the top 40cm of peat, wet when first dug out but tinder-dry now. This was the skin of the taniwha. Imagine putting a match to it, he says. “It's just a fuel really, waiting for oxygen and heat,” he says. “Whereas at Kopuatai, the peat never gets dry enough to burn.”

That saturation, along with its acidity, preserves whatever is in it. “You get these beautiful plant remains,” Campbell says.

Also human, potentially – to see a photo of so-called Tollund Man, found in bog in Denmark, is to be amazed.

Kopuatai is a wonderful archive, Campbell says. “It's a layer cake.”

Bev Clarkson is one who has done some digging through wetland layers. The Manaaki Whenua Landcare Research scientist is a leading light of wetlands research, and features in a chapter of a recently released book, Life in the Shallows.

That chapter centres on work early in her career into the buried forest of Pureora, which was dug up in the 1980s when the forest service was trying to drain an area that was too wet for pines. They found logs about a metre below the surface, beneath a pumice layer. When they dug them out, the branches were brown and had bark on them, and the rimu foliage was green. It was like a living forest, Clarkson says, which oxidised black once exposed to the air.

The trees had been flattened in the Taupō eruption of 232CE, and as ignimbrite blocked drainage channels, the area became a wetland. Clarkson reconstructed the buried forests. She took samples, found foliage, discovered insect remains including now-extinct giant weevils and also found seeds still attached to branchlets of rimu and toru. The stage of their development suggested that the eruption occurred in late summer or early autumn. The year of the eruption was already known, thanks partly to Roman records and also to radiocarbon dating; now Clarkson had also discovered the time of year. The swamp had revealed its secret.

Clarkson, a founding trustee of the National Wetland Trust, has in recent years become interested in paludiculture. About three years ago she travelled to the Netherlands to look into the process. The Netherlands are like a canary in the mine, having started draining land for farming about 1000 years ago. They’re really worried now, Clarkson says, with the land sinking up to six metres below sea level, dikes being damaged by storms and land flooding, while sea levels rise.

“If they don't do something, it's going to cost too much to do the engineering solutions, which are not sustainable in the long term.”

So they are looking into uses for a wetland-loving typha plant related to raupō, including for fodder, fuel and furniture making. Initially, she thinks farmers are being subsidised for the crop. Just to reinforce the obvious parallel, this is on dairying land.

Clarkson says Netherlands landowners have come together with technical experts to make decisions for their own areas. That sees some continuing to be conventionally farmed, some set to be restored and some to be used for paludiculture. It’s a model Clarkson thinks New Zealand needs to follow.

The final goal for ecologists is restoration, but wet farming, with its obvious commercial application, may be an important stepping stone.

But a large multi-year national scale collaborative proposal focused on restoration of peatlands for greenhouse gas mitigation was knocked back in late May when the Ministry of Business, Innovation and Employment declined the $14 million funding application.

The proposal could potentially have included trials on land in the area covered by the proposed Muggeridge’s pump station upgrade, which was itself earlier turned down for government funding.

The upgrade, which had been in line for shovel-ready funding, was intended to allow farming in the area near Ngatea to continue for 50 years, supporting about 20 landowners. Nearby wetlands were to be restored as part of the package.

It initially won approval, but at the start of this year, Government Ministers changed tack and decided against funding. Alternative drainage options will be developed to service the catchment for another 20-30 years.

National Wetland Trust executive officer Karen Denyer is scathing about the Muggeridge’s bid.

“What do they say, Muggeridge has got about another 50 years before it's saline? And if they do all this drainage, they'll get another 30 years out of it or something. And then it's useless. Well, hello, why don't we just rewet it and we can use it indefinitely for something else? It's a perfect opportunity for us to do some trialling, it just needs government and regional councils to throw money at trialling things rather than draining things,” she says.

“We really need to be getting the message out there that this is something New Zealand needs to look at. We need to try different things. We can't expect to keep trying to intensify dairy and reduce our carbon emissions.”

Money for trialling alternatives is, however, slow in coming.

The unsuccessful MBIE Endeavour peatlands restoration proposal was led by Manaaki Whenua and Waikato University, It’s about getting ahead so there are answers for future governments when they latch onto the problem, says Jack Pronger, of Manaaki Whenua.

“There are areas that are now unproductive or struggling to keep drainage up to where it should be and Muggeridge is a good example of that,” he says.

“That would be an obvious starter for starting to think about solutions like this, and it might even be just smaller, wetter areas on farms there that they might want to start thinking about alternative land uses, which could be paludiculture.”

He stresses scientists don't want to be telling farmers what to do. “We want to provide the measurements and the solutions of what it could look like in the future. And it's up to landowners, politicians, maybe regional councils, to try and sort out how that will look.”

The economics of wet farming or restoration could end up more viable depending on how greenhouse gas emissions from current land use is accounted for, Pronger says.

“We're definitely not advocating that that's all restored right now. It's just we have to have solutions coming along for these areas where the crunch is coming.”

Those areas include some of New Zealand’s rich dairying land. It is, Dave Campbell says, a classic wicked problem. “I don't hammer the farmers. It wasn't their choice to drain the peatland, it was several generations ago, and a lot of it was drained under government subsidy.”

Pronger says they will wait for the assessors’ feedback on the failed application to decide on any future approach.

“We’re absolutely going to keep pushing down this road.”

Wetlands researcher Cheri van Schravendijk-Goodman (Te Atihaunui a Pāpārangi, Ngāti Apa, Ngāti Rangi) has a challenge for the Government. Does it have the balls to make change?

“We need some real courageous movers and shakers,” she says.

Everything doesn’t necessarily have to be converted back to wetlands, but a start would be resourcing to test what can be done.

“We've got some ideas about some land use options that could be explored, paludiculture is one.”

Paludiculture chimed with her and others when they heard about it. “When we were looking at it as indigenous people, it resonated because it sounded familiar. It was like, ‘Oh, we've done this before’. We lived in wetlands, and we were harvesting from them and interacting with them every day.”

But paludiculture tends to be monoculture, she says. She is most interested in an approach dubbed Te Wai Haapuapua. That is based, she says, on the notion of finding a rhythm with the natural patterns inside the wetland and its natural construction, and identifying possible value-added products. Rather than having paddocks all dedicated to raupō, there might also be areas for birds, for tuna, for whitebait, for mixed biodiversity.

There is a sense of urgency around getting the mātauranga as older people with the knowledge pass away.

There is, however, still a lot known. “It's there, we've heard it. So that's why I'm hopeful, because I can hear narratives and stories and histories that could give us some tools that we need to do better,” she says.

“As long as we're all living and breathing, and those systems still have water flowing through them, there's always hope.”

Campbell warns that peat wetlands restoration is unlikely to be quick, however. Once the water table is gone, it’s extremely difficult to bring it back, and the original vegetation needs the nutrient-poor conditions to out-compete weeds. Removing the vegetation, the living part of the ecosystem, also destroys the “elastic” property of peat.

The most important thing is to preserve what is left, he says. “No one would think about going and cutting down kauri trees, right? In fact, you'll, you'll be in front of a judge pretty quickly if you tried to, but wetlands have always seemed to be, who cares?”

He says there’s no work being done in old growth forests to measure how much carbon is being taken from the atmosphere or what happens to that carbon in a drought.

At Kopuatai, there is. “This is our old growth forest. And actually, it's even more impressive than that because there's 11,000 years of carbon, two and a half thousand tonnes of carbon per hectare out there. Way more than in a kauri forest and it's more ancient than a kauri forest.

“And yet it's these low plants that no one knows much about. So I get enthusiastic about trying to explain to people how unique these systems are, and how precious it is.”

Kopuatai is Clarkson’s favourite wetland. “You go one and a half, two kilometres out into the middle of it, and you're just there with nature. It's stunning, and you see fernbirds. It's just so different.”

Denyer says New Zealand has magnificent kahikatea swamp areas but some of the wetlands beauty is hidden. “Tiny little sundews, little dragonflies and hidden species. It's not all in your face,” she says. “You’ve just got to appreciate beauty on a smaller scale”.

The making of a wetland

Most Waikato wetlands date back about 15,000 years, when the Waikato River roamed across the region before cutting its current course. They start as swamps, fed by ground water. These are relatively nutrient rich and characterised by species such as raupō, carex and flax. Provided they remain undisturbed, as they age they reach an intermediate stage known as fens, which contain baumea, tangle fern and manuka.

Over thousands of years, the accumulating peat rises, until the only source of water is rainfall, creating the nutrient-poor conditions of a bog, the main wetland type in the Waikato. These harbour members of the jointed rush family, Restionaceae, such as the giant cane rush and wire rush. Because of this they are known as restiad bogs, and they are most extensively developed in New Zealand; overseas peat bogs are more commonly created by sphagnum. Peat is partly decomposed plant material, created because conditions are waterlogged, and too low in nutrients and oxygen for bacteria to completely break it down.