Kauri dieback: Heart of Auckland's Waitākere Ranges clear of disease

Wednesday, 29 June 2022

A survey on kauri health in the Waitākere Ranges has found kauri dieback is limited.
Of the kauri trees assessed, 81% were healthy or had just limited signs of stress.
The results back measures like track closures.

The first long-term survey on kauri health in Auckland’s popular Waitākere Ranges has found kauri dieback is limited to the edge of the regional park and is not widespread.

Kauri dieback is a fatal, incurable disease caused by a fungus-like pathogen, Phytophthora agathidicida, which was first found in the Waitākere Ranges in 2006.

To stop the spread of the disease, mana whenua Te Kawerau ā Maki introduced a rāhui in the ranges in late 2017.

Kauri dieback symptoms were found in 16.5% of surveyed trees in Auckland’s Waitākere Ranges. (File photo)

Auckland Council kauri dieback biosecurity manager Lisa Tolich says the survey results show a cautious approach has helped stop the spread of Phytophthora agathidicida, the pathogen which causes kauri dieback.

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Auckland Council has backed its track closures with fines of up to $5700, manager of proactive compliance Adrian Wilson says.

This was reinforced by Auckland Council’s closure of forest tracks in 2018, backed by fines and compliance officers, until kauri-safe tracks could be reopened.

The survey, undertaken by Auckland Council in 2021, surveyed 2140 kauri out of the 68,000 within the forest, as well as taking soil samples.

It found the pathogen in localised areas on the park’s periphery – showing introduction at several points –but it was slow-moving and had not yet reached the heart of the forest.

The survey results were positive but vigilance was needed to ensure kauri were protected, councillor Richard Hills, chairperson of the environment and climate change committee, said.

“This is encouraging news for our kauri … it’s important we continue our work to protect these iconic taonga from the impacts of disease.”

Te Kawerau ā Maki, which co-designed the project, said the survey showed the need for more action to protect kauri.

“This research provides us the knowledge that can equip us to hope for the future and urge us to act now to avoid ecological failure,” trustee Edward Ashby said.

Kauri live for an average of 800 years and support a forest ecosystem, making them rākau rangatira (tree chiefs) and living tūpuna (ancestors), he said.

“Their importance in Waitākere is really no less important than the long-term survival of the forest as a whole and, by extension, us as an iwi,” Ashby said.

The survey was funded by Auckland Council’s natural environment targeted rate and used low-risk remote sensing technology.

It found the pathogen present in 10% of soil samples and kauri dieback symptoms in 16.5% of surveyed trees.

A further 28% of trees were slightly unwell – potentially due to other factors like drought – and those most sick were near historic timber sites, the coast and the closest uphill tracks.

The results supported the precautionary approach taken since 2018 and continued measures to stop the spread of Phytophthora agathidicida, council kauri dieback manager Lisa Tolich said.

At 55% of the sites surveyed, kauri seedlings and saplings were present, even in areas where the pathogen was found.

“The hope is in future surveys, we will see these young trees survive and continue on their way to maturity,” Tolich said.

CORRECTION: An earlier version of this story said 68,000 trees were surveyed. This was inaccurate information supplied by Auckland Council. The research surveyed a representative sample of 2140 trees. (Amended on June 30, 2022, 11.20am.)