This is a collection of stories, blogs and other information about a new research project run by scientists in New Zealand and the UK. We are carrying out research to develop a new method to study how New Zealand's climate has changed over the past 10,000 years. The method is related to the isotopes found in a rush (Empodisma) that forms peat bogs all over New Zealand. Please delve into our stories to find out much more. Please do get in touch if you would like any more information or have any burning questions!
It is now less than a week until we will board a plane in London for the long flight to New Zealand to meet up with colleagues and undertake the fieldwork for our new project investigating New Zealand’s peat bogs and past climate change. To find out more about exactly what we’re doing in the project please read the previous story in our collection.
Between the project team, we’ve organised and carried out countless fieldwork trips, but I always still find this time period approaching departure is a strange mixture of excitement and trepidation – have I booked and organised everything I need to? Is there some vital bit of kit I should have got hold of which we will only realise is missing when we’re on the middle of a bog and it’s too late?! Let’s hope not! As a researcher involved in studying the past, fieldwork preparation often involves the gathering of lots of heavy and bulky coring equipment to retrieve the deep sediment records that we then study. Although a pain to deal with in transit, having a load of kit with you is at least slightly reassuring. But with this new project, we are just studying the plants growing on the surface of the peat bogs (in particular, the wire rush, or Empodisma to give it its Latin name) to understand more about how they react to changes in climate. This means the pile of kit I have gathered together in my office over the past few weeks (pictured!) is rather small and certainly very un-reassuring!
We have also been spending some time finalising the permissions we need to access all the sites we would like to work on. This is an often complicated task that has been admirably handled by Rewi Newnham at Victoria University, on the ground in NZ. At one site, there are five local stakeholders with a vested interest including two local iwi, conservation and farming interests. Thankfully everything seems to be sorting itself out and it’s great news that some of those interested parties will be joining us out in the field next week. I really believe that as academics funded by the public purse we have a duty to let as wide a range of people as possible know about our research, so this is a great start. To further this goal, we will post several blogs over the next few weeks on different aspects of how the fieldwork is going on the OurFuture site. If you’d like to know any more about the project or have any questions, then please get in touch.
A week into our fieldwork trip to study New Zealand's peat bogs and the North Island is done! To say our trip has been something of a whirlwind so far would probably be leaning towards understatement. Rewi met Dan and I off the plane at about 2pm last Tuesday morning, though to be honest, after 27 hours in transit, our bodies had very little of what time of day it really was. Apart from a short power nap for half an hour on my part, we managed to stay awake for the whole of the five hour drive to Kaitaia where we arrived and gratefully fell straight into a comfy bed.
There was no time to ease ourselves into the swing of things – a schedule covering six bogs from the far north to the far south in a smidgen over two weeks allowed for no such luxuries. So, bright and early, we were off to Tangonge Bog, just west of Kaitaia, where we met up with several people who joined us out in the field; a local botanist who has been central in efforts to preserve the remaining remnants of the bog over the past few years and members of the two local iwi, Te Rawara and Ngai Takoto. It was great to be able to learn about the area from them and to let them know about what we hope to learn from their site. The stories of how recently what is now a pretty dry fragment of bog used to be a large lake surrounded by extensive wetlands teeming with bird life were astonishing. The drainage of the land for agriculture has slowly sucked the water from the bog and it was heartening to learn that the iwi want to restore the wetland to its former glory in the near future. I really hope they can succeed because Tangonge is one of the final remnants of wire rush dominated bog in far Northland that deserves to be preserved for a multitude of reasons, not least its central place in the local Maori folklore and history.
After a morning on the bog we retired to the Te Rarawa marae at lunchtime to which we were kindly invited. It was a wonderful experience including lots of traditional Maori greetings (touching of foreheads) and our attempt (which went quite well if I do say so myself) to sing a Maori song as part of the welcoming ritual. Rewi gave a greeting in Maori which Dan and I were both surprised and very impressed by – in Rewi’s great modesty he had said only earlier that day when Dan asked, that his Maori was “coming on ok”! We returned to the bog in the afternoon to finish off our sampling and got caught in a massive rainstorm, which only served to fuel our discussions on the way back south towards Auckland at the end of the day about the climatic differences in terms of rainfall patterns and sources that we are trying to see if the wire rush records in its isotope record.
At each site, including at Kopouatai Bog, New Zealand’s largest and most famous peat bog where we found ourselves the next day, we are taking a range of plant and water samples to test our hypotheses. We want to see whether the oxygen isotopes in roots and shoots of the wire rush and the water sources it uses to grow reflect spatial (throughout New Zealand) and temporal (over the course of a year) variation in the oxygen isotopes in rainfall. We also want to understand whether the carbon isotopes are influenced by the moisture status of the bog, reflecting the amount of rainfall received in the past. If we can figure all of this out, it means we might be able to use isotope records from wire rush dominated peat cores to study past changes in precipitation, something that’s currently very difficult to do in New Zealand.
At Kopouatai, we’re being ably assisted in this task by Jordan, a PhD student from nearby Waikato University who is working on the site measuring gas fluxes. We met Jordan at a farm near the edge of the bog and drove along bumpy lanes as far as we could until the vegetation changed dramatically from farm paddock to something distinctly more natural. There was still a couple of kilometres of fringing vegetation to tramp through until we reached the bog itself and what a wonderful place it was. Bogs may not be everyone’s cup of tea and on the face of it might be seen as rather featureless, but I find them very beautiful places. Kopouatai was a vast open landscape, with a soft wind sending the vegetation wisping away in gentle waves. Situated in the low lying Hauraki Plains, it is hemmed in to the east and west by distant jagged hills. As we worked away, our techniques already a lot more slick than the first day, I felt a wonderful sense of peace and serenity overcoming me. It was pretty hard to feel this was my job and once we had finished I didn’t really want to leave and could easily have sat out on the bog all evening watching the sun go down and feeling at one with the world.
Our final site in the North Island was Kaipo Bog in Te Urewera National Park and it was an epic trek to get there. From the flat plains of Kopouatai we wound our way up into the hills, finally arriving at Lake Waikaremoana, camping on the lake shore (or actually, not quite on the lake shore due my slightly inept scoping of the campsite, much to Rewi and Dan’s consternation!) From the lake it was an hour of hiking through beautiful native beech forest, damp in the morning air with shafts of sunlight piercing through gaps in the canopy, to Lake Waikareti. We rowed across the lake in about an hour, saving ourselves at least a four hour tramp in the process. From our landing point at Sandy Bay hut, our accommodation for that night, it was a further two hours of tramping to the bog. This was our first meeting with the more slender species of the wire rush, the northern sites being dominated by its more robust cousin. The bog surface was an intriguing mixture of hummocks formed of vegetation and low lying watery hollows ready to trip up an unwary footstep. The sampling by now was a slick process and after a further two hours walk back to the hut, we felt we had earned a lazy evening on the veranda, overlooking the pristine lake as the sun sank over the horizon and the flames of an open fire fluttered on the beach.
Five days, three bogs and 87 samples since we touched down on New Zealand soil; let’s just hope the South Island goes as well...
Another dividing line swishes by, another town holding a world of interesting diversions is avoided, another intriguing landscape is no more to us than a speculative conversation. The South Island is big. We’re only here for a week. Result: driving and lots of it! From the moment the ferry docked in Picton late on Wednesday afternoon, the progress has been relentless, first to Saint Arnaud that evening where we camped by Lake Rotoiti in the Nelson Lakes National Park. Then to near Westport the next morning where the first of our South Island sites was located.
And that’s when Plan A started to go a little awry. We’d planned to sample a site called Anderson’s Pakihi, but when we got there the fringing scrub was thick and in the most accessible part of the site the vegetation was not what we were looking for ... the wire rush was conspicuous by its absence. We found it on the far side of the site on some higher ground alongside a house, but behind a high deer fence. There was nobody at home so our access was again foiled. It’s always a little tricky to know what to do in these circumstances, but given our schedule a quick decision was needed. That decision saw us saying goodbye to Plan A and hello to our new friend, Plan B. So onwards we plodded south, this time towards our next site at Okarito, just north of Franz Josef Glacier.
We weren’t too worried about passing over Anderson’s Pakihi because in the North Island we had learned about an alternative site near Dunedin. The reason we’re on this crazy trip trying to cover so much ground in two weeks is because we want our samples to cover a gradient over the full range of different types of rainfall received across New Zealand. Rainfall, specifically the oxygen isotopes in rainfall, differs depending on where it has originated from. So rainfall in the north of New Zealand that comes more from the sub-tropics has a different isotopic signature to rainfall in the south that will generally be blown in on the Westerly winds. It’s these differences that are driving our site selection and as it turns out, the new site near Dunedin gives us greater variability than Anderson’s did. Amazing what you can learn on the ground that you can’t sat at a computer on the other side of the world!
So we put the new site, Swampy’s Summit, in our pockets for later in the week and headed to Okarito. Another three and a half hours on the road saw us get there late on Thursday, but with a few hours of light remaining, we decided to press on and get some South Island samples in the bag to boost morale. This we did with great efficiency as the late evening sun sunk towards the horizon and coloured the vegetation a deep golden brown. Okarito was by far the wettest site we had visited so far, again a good thing in terms of capturing a range of environments in our samples. Not such a good thing however for the comfort of my feet as I took a step on an innocent looking patch of ground only to disappear down to my thigh!
The next day was a mammoth road trip, about 600 km from Franz Josef Glacier down to Invercargill, but got us within firing distance of our penultimate site at Otautau. The sampling here went off without a hitch the following morning; a friendly local farmer was happy for us to use his track along to the edge of the bog, access was easy save the jumping of one ditch and the wire rush was abundant. Again it was a very peaceful spot, with the only sounds the calling of birds flitting around in the blue sky above and snowy mountains on the distant horizon. So with a spring in our step, we headed off towards Dunedin, ready to bag our sixth and final site and toast a successful trip.
And that’s where Plan B started to go a little awry. On a cold, blustery Sunday morning, we could be found walking up to Swampy’s Summit high above Dunedin, well wrapped up against the elements, climbing the last two kilometres along the dirt road past the locked gate that marked the edge of the scenic reserve. Clouds rose up the hill side and blew about us, from time to time obscuring the expansive views of the town and surrounding countryside laid out below us. We made the summit and found the bog. The wire rush, however, had once again decided on a disappearing act. We recognised plenty of the vegetation we were used to seeing on our previous sites but search as we might, there was none to be found. So it was with a sense of frustration that we retraced our steps and tried to decide what to do next.
The problem was, there were a lot of potential versions of Plan C. We could head back south or way up north in search of other sites, but neither was very practical either due to site access issues, further risk of missing wire rush or simply having too far to travel in too little time. In the end we decided on a Plan C that brought our fieldwork trip to a rather stuttering end; Rewi will sample another site in the North Island when he goes there in a couple of weeks for another project. So we’ll end up with our six sites and fingers crossed the results we need to test the hypotheses of our project, but not quite in the way we envisaged.
We always know travelling the length of New Zealand in such a short time would be a rush and indeed it proved to be just that, but worth every hectic minute. Personally it has been a wonderful learning experience and the chance to engage with the local iwi at Tangonge was a real privilege. As with most scientific projects, the real work begins when the samples arrive back at the lab in the UK. The hours of lab work and analysis is really where we earn our daily bread and I’ll post updates as the project develops to let you know how we are getting on. In the meantime, please get in touch if you have any questions.
Here we explain more about the science behind the research we are about to undertake. Our fieldwork in New Zealand will take place in November so over the coming weeks we will post stories of how we are getting on! Please get in touch if you have any questions!
The study of how and why climate has changed in the past is an important element in the scientific drive towards understanding and predicting how it may change in the future. We can answer a range of questions about past climate by studying one of a number of environments that hold a record of past changes. There are answers to our questions in ice cores, the varying width of tree rings, the growth rate of stalagmites in caves or in the make up of sediments such as those at the bottom of lakes or in peat bogs.
Peat sediments develop steadily over thousands of years and in the type of bog we study, the growth of plants on the surface is related directly to the prevailing climate. So if the climate gets wetter, the plants change in response. Then, if the climate gets drier, they change again. As the bog grows upwards, a record of all of those changes is preserved, so we can now stand on the surface, take a core back through all the layers and analyse what's been happening.
There are many methods we can use to do this. We can look at the plants themselves, or at amoebae that live on the bog surface. Another method that has only recently been applied to studies of peat bogs is to look at changes in the ratios of different isotopes captured in the plant remains.
Isotopes are atoms of the same element that contain the same number of protons, but a different number of neutrons. Isotopes can be either stable or radioactive, but here we are just interested in the stable isotopes. Oxygen, for example, has three different stable isotopes known as oxygen 16, 17 and 18. More than 99% of all oxygen is oxygen 16, which contains eight protons and eight neutrons. Only about 0.2% is oxygen 18, which has two extra neutrons, making it heavier than oxygen 16.
The isotope signal in bogs comes from the precipitation that plants use to construct cellulose, an organic compound that forms their cell structure. We can relate the record to past climate because, under different climatic conditions, lighter or heavier oxygen isotopes are more common in precipitation.
Previous studies of changing isotope ratios from peat bogs have used a particular type of moss, called Sphagnum, from which to derive their measurements. This is effective, but is also limited, both to geographical areas where Sphagnum occurs and also to the parts of a core where Sphagnum is present; nobody wants gaps in their record.
We want to address these two issues by testing the applicability of studying isotopes in a different type of peat that is found in regions where Sphagnum is less common. In the Southern Hemisphere, bogs are generally dominated by higher, or vascular, plants rather than mosses; these are plants that can actively control the movement of water and nutrients in their tissue. Bogs dominated by higher plants are widespread globally, but because of the differences in biology between them and mosses, we can't be certain that the isotope method is applicable without rigorous testing. Results from a piliot study we carried out suggest that a reliable record of past climate can be derived from these bog types, but to be certain, more research is needed.
We will study bogs in New Zealand, dominated by a species of rush, to perform further tests. We will study the rush on different sites over the course of a year to fully understand how the isotope signal is incorporated into the plant remains. If we can demonstrate that the isotope method can be applied to this peat type, it will be a big step forward; the method would be applicable over a much wider geographical area and we will be able to address pressing research questions about past climate change more so than at present.