It’s summer holiday season here. So many people I know are heading away to discover new places or return to loved haunts and I can’t help thinking back over the times we have travelled. It strikes me that so many of the places I have visited have trees associated with them in my mind; a twisted olive hung with lanterns, a caged Wollemi pine, a massively buttressed mahogany, a towering giant redwood, a fragrant Monterey pine, a windswept banana palm – the list goes on and on in my mind. Each tree will take my imagination back to a special place, each tree deserves a blog post in its own right – and maybe one day it will have – but today, this holiday time, if I have to pick one tree that always inspires me when I think of it, I pick the kauri tree of Aotearoa, of New Zealand.

The kauri, Agathis australis, is one of the largest trees in existence. Five years ago, Mark and I were taking the children to see them. It was our great escape, our reaction to an exclusion and subsequent placement of our autistic son, Joe, in a special school that turned out not to be suitable for him. Mark and I took our children (Joe then 10, Peta 7, Melody 4 and Amos 1), and backpacked round New Zealand for nine weeks. The kauri trees were the first destination on our trip after a few days near Auckland to get over the jet lag.

We set off in the hire car on the day we had scheduled in for our visit to the kauri trees. We hadn’t gone far when Melody suddenly said she felt sick. There wasn’t time to stop before she had vomited spectacularly, over herself, the hire car and the car seat we had needed to hire for her. There was nothing else to do, but turn back to camp. I remember it was Sunday and we were in a pretty remote place – we were extremely lucky that there was a petrol hut a little way past our camp from which we were able to buy their one small bottle of disinfectant. We spent the rest of the day, with Melody in bed, washing clothes, car seat covers and trying to get the smell of sick out of a car that was our transport for the rest of the trip.

The next day was the day for moving on, but we did some quick shuffling and decided we’d look at the trees on the way, just arriving late at our destination. As we packed, and were ready to set off, Melody upset coffee all over the flat-pack highchair seat and Amos filled his nappy so badly he need a change of trousers and vest too. We unpacked, repacked, bundled four children into the car and set off. We couldn’t find the trees… we were looking for particular ones. There are a number of notable kauri trees in the north of New Zealand, but two are probably more famous than the rest – Tane Mahuta and Te Matua Ngahere. We were looking for Tane Mahuta, but eventually ended up at the path to Te Matua Ngahere – the Father of the forest. That was fine. We’d settle for that. We parked and all set off down the track. The first thing that struck me was the silence, the lack of birdsong – it felt unnatural. But as we walked through the bush of tree ferns, we began to enjoy the walk. We arrived at the sign to Te Matua Ngahere as the drizzle began to fall. We took shelter. Thunder rolled overhead and the deluge began. Our cagoules were in the car. We were soaked to the skin in minutes. We trudged back the way we had come. At the car, we unpacked bags again under the shelter of the open car hatch-back. Everyone needed a complete change of clothes. We ate all the food we had left, which was a random assortment of dried fruit, bread and chocolate, then took the advantage of a clearing in the weather to set out again.

This time we made it. The rain held off until we arrived at the sign bearing the name ‘The Father of the Forest’. As we rounded a corner of the board walk, there it was in all its ancient glory. Two thousand years old, towering huge through the canopy, its trunk a gigantic wooden wall of might in front of us. No photograph can ever convey the size of these trees, the feeling of insignificance and awe they inspire, the absolute majesty they command. At a height of 29.9 metres and a girth of 16.41 metres this tree was breath taking. You can’t look at all of the tree at once, just a bit at a time – its crown, its trunk, its base largely hidden in bush. It’s hard to comprehend the sheer amount of tree involved. It felt faintly ridiculous, irreverent somehow, to struggle into waterproof leggings and cagoules (with all the accompanying resistance from little ones) in the presence of such a life force. But the deluge had begun again, and it was necessary.

A second change of clothes and a drive later, we found Tane Mahuta. Though a mere 1,500 years old, it is staggeringly big, the largest remaining kauri tree in New Zealand. 51.2m tall and 13.77m in girth, its name understandably translates to King of the Forest. And bizarrely, I recognised this tree. It was familiar, the two big knots in the front, the crown. It was the same tree I had seen fourteen years earlier. So much had changed for me in those fourteen years, and yet this tree had just stood here, unchanged. This King of the forest had undoubtably seen the first Maori arrive in the ancient forest, the first European settlers after that. It had existed when New Zealand’s unique flora and fauna were undamaged by man, when kiwi and moa foraged beneath the canopy unthreatened by extinction, when songs of other birds now gone or restricted to offshore islands rang through their branches. And it stands there still in eerie silence.

The length of time these trees live for is practically incomprehensible; they seem almost permanent. To any one human, these trees must appear unchanging throughout that person’s life; they must seem timeless, forever present. But they are not. The kauri, as so many things on this planet, is threatened by the activity of humans.

Tane Mahuta is the largest remaining kauri in New Zealand, but there used to be larger. There are rumours of stumps measuring 20 metres in girth and stories of a time, not too far back in history, where these ancient kauri forests covered large tracts of land. But people came to New Zealand and found the kauri. Its timber was beautiful – blemish free and fine grained – and the resin the kauri produced was in demand for furniture varnish, to gilt-edge books, as denture mounds, and it is still considered to be one of the finest varnishes for musical instruments. There was a time when the kauri tree was thought of as so plentiful, it was simply burnt if in the way, cut down to clear land for crops and towns. Sustainability and the idea that resources might run out were just not something anyone ever considered. Increasing ingenuity was employed to cut and move the massive logs – special tools were made, up to twelve teams of bullocks would be used to drag logs over makeshift tracks and where this was too difficult, dams were built in valleys. The dams were left to fill while the trees were felled, then opened in order to flush the logs down towards the bigger water courses along which the timber could then be floated. During the 19th and 20th centuries, over 3000 dams were built, almost all the kauri trees were cut down and the ground remaining often searched or sluiced to uncover any residual gum. Today, very little of the ancient kauri forest remains; three quarters of all the surviving mature kauri trees are found in two small forests barely covering one hundred kilometres squared.

It would be tragic to lose the kauri tree, but losing the kauri forest is about so much more than just losing a tree species. For a start, the tree itself is absolutely unique. It is a primitive type of pine, found only in New Zealand, though once it grew in Australia and South East Asia. Visually kauris are stunning, partly because of their size (it is thought they can grow to over 50m tall and 20m in girth), partly because their trunks are beautifully scalloped (a pattern caused by the flaking bark which helps to defend the tree from parasitic plants) and partly because of the magnificent crown resting on the columnar trunk. The biology of the kauri is fascinating too. Unusually, it takes its nutrients from the organic litter near the surface of the soil through a shallow network of fine root hairs. These feeding roots house symbiotic fungi which improve the trees ability to take up nutrients. While perfect for the job of feeding, these roots are very delicate and don’t penetrate far down into the soil – completely unsuitable for holding up such a massive tree. Instead, the kauri has a second type of root – peg roots – which grow straight down, anchoring the trees firmly into the ground. It is the kauri’s way of gaining nutrients, combined with the trees longevity, that gives the trees the ability to gradually modify the soil around them and so compete with the more recently evolved and faster growing angiosperms.* And if losing all this isn’t bad enough by itself, losing the remaining kauri forest would mean losing some of the most ancient forest in the world, forest that is vitally important as a refuge for threatened wildlife from the kiwi to the kauri snail (a carnivorous giant land snail which I have had the privilege of holding… after it had slurped up a worm like spaghetti.)

The need to conserve the kauri has been recognised for years now. Logging of the trees became illegal in 1952, board walks were built around vulnerable trees to protect the delicate feeding roots from being crushed by visitors, and access was restricted in sensitive areas. But just as things started to look up for the kauri, trees started to die inexplicably. Eventually, it was discovered trees were suffering from infection by the fungus Phytophthora agathidicida. Kauri die-back as it became known, has no cure, but its spread can be prevented by good hygiene. Visitors to the kauri forests are urged to scrub and spray the soles of their shoes with disinfectant, stick to the board walks, and to avoid the tree roots as any movement of the soil around the roots could spread the disease. The survival of the kauri hangs in the balance. But there is one last thing worth bearing in mind. For those interested in finding a machine that will take up and hold the carbon we have pumped into the atmosphere, look no further. The total carbon content in the living above-ground biomass, plus the dead biomass of a mature kauri forest comes in at second place out of every forest type recorded anywhere in the world. Worth a thought when we search for ways of sequestering carbon long term, and what a fantastic way to do it…

Who knows what is still to happen under the watchful gaze of these most ancient of trees.

 

 

 

*This is getting a bit technical, but for those who are interested, the leaves of the kauri are acidic. This serves two purposes. Firstly, it slows the decomposition of the leaf litter and any fallen kauri branches, meaning the nutrients are available in the leaf litter for the kauri to feed on for longer, but meaning these nutrients do not move into the soil to become available for competitors so quickly. Secondly, any nutrients that do make it into the upper layers of the soil are quickly leached further down into the deep soil by the acid, again, putting the nutrients out of reach of competitors. The kauri basically starves the opposition.