Results from the first long-term kauri health monitoring survey undertaken by Auckland Council in 2021, reveal the distribution of the Phytophthora agathidicida (kauri dieback) pathogen is limited to localised areas on the periphery of the regional park and is not widespread.
The distribution shows a pattern of introduction at several points, supporting the theory of a slow-moving invasive soil-borne pathogen that has not yet achieved its potential range.
Environment and Climate Change Committee Chair Councillor Richard Hills says the survey results are positive, but vigilance is needed to ensure kauri are protected from dieback disease.
“This is encouraging news for our kauri, as is the finding 81 per cent of the population surveyed were considered healthy or had only some signs of stress, it’s important we continue our work to protect these iconic taonga from the impacts of disease.
“While the disease still presents the risk of spreading to other areas, it is pleasing to know the pathogen is slower moving than we first believed, that large stands remain unaffected and there is hope for the next generation of kauri.”
The survey, undertaken in 2021, was funded by the Natural Environment Targeted Rate, (NETR), with extensive input from national scientists and international experts. Rather than employ the risk-based approach of previous surveys, new remote sensing technology and epidemiological modelling was used to understand the health of the kauri population.
The project was co-designed and delivered in partnership with Te Kawerau ā Maki.
Edward Ashby of the Te Kawerau Iwi Tiaki Trust Board says local iwi regard kauri as rakau rangatira (chiefly trees) and living tūpuna (spiritual conduits to the past and future).
“Mātauranga Māori holds environmental health is an integrated system that must be managed holistically.
“It is not just the presence of a pathogen in isolation but more the combination of the harmful ways we interact with nature that degrades the thread of life.
“Western science, including hypotheses that may be generated from these results, are beginning to align with this broader understanding of the interconnectedness of the world,” he adds.
“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. Whether we collectively have the wisdom to, remains to be seen but the whakataukī of old holds promise for the future.”
Tiakina Te Wao Nui a Tiriwa, hei oranga mou
If we all take care of the Great Forest of Tiriwa, in return we will all flourish
Since closing large expanses of forested areas in May 2018, Auckland Council has relied on a precautionary approach to the management of the region’s kauri forests.
“The survey findings support the management approach council has taken to date,” says Kauri Dieback Manager Lisa Tolich.
“The strong association between P. agathidicida and symptomatic kauri and localised distribution of P. agathidicida in the forest, reinforces our knowledge that the pathogen is an ‘infectious’ disease, in that it is actively spread between hosts.
“This supports the continuation of the strategies to slow or stop the spread of P. agathidicida within the Waitākere Ranges and to other sites throughout the region which are based on the first principles of infectious disease control: isolation, hygiene and treatment.”
At more than half of the sites 55 per cent surveyed, kauri seedlings and saplings were present, even in areas where P. agathidicida was found.
“The hope is in future surveys, we will see these young trees survive and continue on their way to maturity,” adds Lisa.
The results of the latest survey will help support the management of interventions to protect the kauri of the Waitākere Ranges into the future.