New Zealand’s peat bogs reveal climate history
New Zealand’s ancient peat bogs may hold the key to understanding how the climate has changed in the past 10,000 years and how it may change in the future according to a team of scientists from Victoria University and the University of Exeter in the United Kingdom.
The scientists spent November 2012 travelling the length of New Zealand examining peat bog ecosystems from Tāngonge Wetland just west of Kaitaia in the Far North to Invercargill’s Ōtautau Bog in Southland. They took plant and water samples and sediment drill cores representing many thousands of years of gradually accumulated peat.
What are isotopes?
Dr Katja Riedel of NIWA explains what isotopes are and how they are being identified and measured from the gas samples collected in the ice cores from Antarctica.
Isotopes in wire rush plant tissues
The team included Professor Rewi Newnham, a physical geographer at Victoria University, and Professor Dan Charman and Dr Matt Amesbury from the University of Exeter in the UK. The researchers are particularly interested in a plant that grows in bogs, the wire rush Empodisma. They will be examining the isotopes captured in the plant tissues of samples they collected to see how the plant incorporates a record of climate into its tissues as it grows, dies and eventually forms the peat that the bogs are made of.
“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,” writes Dr Amesbury in his bog blog.
At Kopuatai Bog in the Hauraki Plains near Paeroa, New Zealand’s largest peat bog, the team were assisted by Jordan Goodrich, a PhD student from nearby University of Waikato, who is working on the site measuring gas fluxes.
Kopuatai Peat Dome
The Kopuatai Peat Dome on the Hauraki Plains covers nearly 10,000 hectares.
The research was funded by the UK’s Natural Environment Research Council.
Past climates
Past climate can be studied in a number of ways by examining environments that hold a record of past changes. These environments include ice cores, tree rings (including fossilised trees), the growth rate of stalagmites in caves and sediments laid down over time in the bottom of lakes or in peat bogs.
Dating ice cores
Dr Katja Riedel of NIWA explains how ice cores are dated. The researchers often rely on events like volcanic eruptions to determine how old the ice is.
Related content
What is an isotope? Your students can find out by watching these video clips in which two scientists explain what an isotope is and how they are used in research.
What are isotopes? – Dr Fiona Petchey (Waikato Radiocarbon Dating Unit based at the University of Waikato) explains what an isotope is. She then focuses on the isotopes of carbon.
What is an isotope? – Dr Katja Riedel (NIWA) explains what isotopes are and how they are being identified and measured from the gas samples collected in the ice cores from Antarctica.
Find out more about peat bogs in the Waikato.
Lake sediment cores provide a window into the history of a lake and its catchment. Scientists are using the past to learn how to protect and manage what we have and make restorations for future generations.
Useful link
Dave Campbell was interviewed in 2014 by RadioNZ about his work on the Kopuatai Peat Bog and carbon research, find out more here.
