Reading The Kauri Rings

19 August, 2002

Reading The Kauri Rings

Kauri trees and even the kauri clock in your kitchen may help unravel the secrets of El Nino weather conditions, according to researchers at The University of Auckland.

Dr Anthony Fowler, a senior geography lecturer in the Faculty of Science, says his research team has begun a three-year research project studying kauri trees and climate change.

A research team led by Professor Paul Williams at The University of Auckland was recently awarded a $1.6 million Foundation for Research, Science and Technology grant to study climate change. The kauri trees research is an integral part of the larger project.

Dr Fowler, a climatologist and principal investigator on the project, says not enough is known worldwide about El Nino weather patterns - despite the fact it has global implications.

"In the late 20th Century El Nino were unusual as they were more frequent and intense. We don't know whether this was because of climate change or just natural variability.

"El Nino isn't something that only happens in New Zealand, as North America and the Tropics are also affected. But we don't know how long the El Nino has been around and whether conditions are becoming more severe," he says.

Tree rings are a prime method for assessing climate change and Dr Fowler believes kauri trees could be particularly helpful at uncovering El Nino's secrets.

"We completed a project recently that showed kauri trees respond unusually to climate. Whereas most trees like warm moist conditions, Kauri's actually prefer the conditions you get in an El Nino - cool and dry.

"That discovery was a big surprise and opened up an opportunity, because we realised Kauri could give us more extensive information about El Nino conditions," he says.

Living kauri will supply the researchers with a history dating back 1000 years, while sub-fossil material such as tree stumps and museum artefacts from the old logging days will provide the researchers with a history hopefully dating back about 4000 years.

"A potential source for this information will come with the help of people who are using kauri stumps to make commercial products such as clocks. These could well be critical materials."

Dr Fowler says researchers would be able to supply commercial operations with details on the age of the trees, and receive samples in return.

"Working with tree rings is a bit like working with fingerprints. You see a pattern in the rings and can cross date. So we might find an old log that we don't know the age of, but by looking at the pattern of the rings we can work it out.

"If you have a significant climate event such as an El Nino, then all the trees will have the same pattern," Dr Fowler says.

Using these resources, the researchers will examine kauri tree rings from trees growing between Hamilton and Northland.

The researchers will take a small core sample from the live trees and use a microscope to look at the rings. They are then able to learn what effect climate conditions had on the trees, and how often such climate events took place.

"We know the El Nino has been around for quite some time. But I believe that over the last few decades we've had more intense El Nino's and they become more frequent.

"The records currently only go back to the 1800s but we hope our research will enable us to get more historical detail and hopefully achieve a better understanding of natural climate.

"This will give us a better basis for recognising if and when climate change caused by human activity exceeds the bounds of natural variability. Whether that has happened yet is a hotly contested topic," Dr Fowler says.

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For further information, contact:
Anthony Fowler
Faculty of Science
09 373-7599 x 5380
a.fowler@auckland.ac.nz

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