A Te Ngāherehere o Kohukohunui / Hūnua Ranges Kauri Population Health Monitoring Survey just published, has revealed no detectable signs of kauri dieback (P. agathidicida) in the Hūnua Ranges.

The health monitoring survey, the first for the Hūnua Ranges, was carried out between March and November 2023. It was designed to establish the health of kauri, including whether the pathogen might be present in the ranges and collected comprehensive data on 561 kauri trees.

The survey was a collaborative effort between Auckland Council, the Department of Conservation, and ngā iwi mana whenua o Te Ngāherehere o Kohukohunui - Ngāi Tai ki Tāmaki, Ngāti Tamaoho, Ngāti Whanaunga, and Ngāti Tamaterā.

Results indicate a robustly healthy kauri population, with over 95 per cent of trees surveyed in excellent health - a much higher rate than the 55 per cent of sites observed in the 2021 Waitākere survey.

Furthermore, over 92 per cent of surveyed sites showed the presence of healthy seedlings or saplings, indicating strong regeneration and a healthy ecosystem.

Importantly, the survey found no evidence of kauri dieback within the study area.

Chair of the Policy and Planning Committee Councillor Richard Hills says Auckland Council has made significant investment into both kauri protection and surveillance since 2018, and the report shows these efforts are paying off.

“The kauri dieback pathogen has been detected in most regions where kauri grows in New Zealand, so to have 97 to 99.9 per cent confidence the Hūnua Ranges area is dieback free, is remarkable,” says Councillor Hills.

“As a popular destination, recreational activity in the Hūnua Ranges is high and the results demonstrate the importance the community places on protecting this special area and supporting the council in its efforts to keep kauri healthy and thriving.

“The assurance this report affords us is critical for ongoing forest management and underscores the necessity for proactive conservation efforts and community engagement to preserve the health of the Hūnua Ranges and all of our precious forests.”

Auckland Council’s Principal Biosecurity Advisor, Dr Sarah Killick says protecting kauri from the threat of dieback is paramount to ensuring the specie’s survival.

"The findings of this survey provide a baseline for monitoring kauri health and will guide future prevention strategies to safeguard this precious ecosystem."

The survey's risk assessment highlighted areas most vulnerable to pathogen introduction.

A similar survey in the Waitākere Ranges in 2022 indicated kauri dieback was strongly associated with historical and recent soil disturbances. In areas where it occurred, kauri appeared to be more prone to poor health and vulnerable to disease.

Evidence indicates soil and forest disturbances are introduction pathways for kauri dieback, emphasising the importance of preventing soil movement as key to protecting the health of this forest.

Enhanced AI and machine learning tools have helped map kauri, building on the successes of similar efforts in the Waitākere Ranges.

Dr Killick says ongoing monitoring will be critical to track changes in kauri health over time, considering factors such as land use, environmental management, and climate change.

The survey will continue to be carried out every five years.

Read the 2023 Hūnua Ranges Kauri Population Health Monitoring Report here

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