Swamp kauri are ancient logs of climate change records

Contractor Rupert Newbold chainsaws a 3000 year old swamp kauri stump on a farm near Ardmore. Photo / File

Scientists using swamp kauri to create a record of the weather going back thousands of years are hoping to work more closely with those digging up and selling the trees.

The buried trees - most often found preserved in peat bogs in Northland - can contain information on the climate as far back as 60,000 years, NIWA scientist Andrew Lorrey said.

This was because a single kauri could live from between 600 to 1000 years, with some found to have been preserved in swamp lands for tens of thousands of years.

New Zealand was the only country to have preserved trees this old, Lorrey said.

It made the logs perfect to help researchers create a historical record of the weather and answer one of the biggest questions in climate science, about how the El Nino-Southern Oscillation would be affected by global weather changes.

Lorrey said the El-Nino Souther Oscillation was "very important to our regional climate, [and drove] huge climate anomalies, such as droughts and floods, around the globe".

Currently, a climate record based on kauri tree rings stretched back 4500 years.

Further back than that, the data was incomplete but some kauri samples were aged between 30,000 and 60,000 years.

To fill in the gaps in the kauri climate "calendar", the NIWA team hoped to access more of the trees being dug up and sold by industry.

"For instance, we have a big gap of wood between 13,000 and 27,000 years old.

"If we were to get our hands on that we would have a shot at putting together an absolutely epic calendar-dated tree ring record," Lorrey said.

He said some researchers feared vital information would be lost forever if kauri were sold without scientists first getting the chance to take a sample.

This was particularly the case between 2011 and 2014 when the market for swamp kauri rapidly grew, and "things were very difficult to keep track of," NIWA said.

-AAP