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Image: Seeds of Doubt

Seeds of Doubt

By Guest Author • 11/01/2021


NOTE: This is an excerpt from a digital story – read the full story here.

Tess Tuxford

Ko te Kauri Ko Au, Ko te Au ko Kauri
I am the kauri, the kauri is me

Te Roroa proverb

In Waipoua Forest, at the top of the North Island, New Zealand’s largest kauri tree stands at over 50 metres tall. According to indigenous Māori culture, its namesake Tāne Mahuta was ‘The God of the Forest’.

As the story is told, at the beginning of the universe there was only darkness. Ranginui (the sky father) and Papatūānuku (the earth mother) lived together in a never-ending embrace, their children nestled between them away from the light.

One day, tired of the perpetual darkness, Tāne decided to free himself and his siblings. Using his great strength he pushed his parents apart, forcing his father high into the heavens. Their separation allowed light to flood into the world and gave Tāne dominion over the forests.

Many iwi consider the tall and ancient kauri to be the legs of Tāne keeping his parents apart. Kauri are taonga and considered ancestors. They serve as sources of inspiration in songs, dances and proverbs.

For Māori the health of the forest is intrinsically linked with the health of the people. Failure to protect kauri is a failure to ensure the wellbeing of future generations.

“This is timber country”

The first threat to the survival of kauri was the settlement of Europeans in New Zealand and the start of the timber industry. In 1840, two-thirds of the country was covered in native bush. Kauri forest accounted for one million hectares of this land. As a species it has existed for twenty million years.

For many decades the kauri bushman has existed in the lore of New Zealand history as an icon of mateship and endurance. The gargantuan and long-lasting kauri trees stood as a worthy adversary to test the tenacity and ingenuity of these European settlers.

Kauri are believed to live as long as 1500 years, possibly even longer. The kauri felled during this time are said to have had a circumference of up to twenty-six metres – almost twice that of Tāne Mahuta. In familiar black and white photos logging gangs stand together atop the felled trees, like hunters displaying their biggest trophies yet.

But while native forestry may have built the country we know today, only seven thousand hectares of kauri forest remain. The exploitation of native trees disseminated the forest ecosystems and have left kauri extremely vulnerable.

While the trees are now technically protected by the Department of Conservation, their longevity is at risk once again. This time the impending threat is proving much harder to stop than the swing of an axe.

Phytophthora

Phytophthora are species of Oomycota, fungus-like microorganisms which are responsible for infecting a variety of different plants. One of the most well-known is Phytophthora infestans, better known as potato blight, which caused the Irish Potato Famine in the 1840s.

In New Zealand, the species threatening kauri is named Phytophthora agathidicida. It is the cause of the root rot disease known as kauri dieback. Initially discovered in 1972, the number of infected trees has increased over the last ten years. There is currently no known cure for infected trees and the disease is ultimately fatal for kauri.

In the initial stages of infection there are almost no visible symptoms of disease. This period can last for several years before the tree enters the chronic phase. At this point, excessive gum bleeding and the loss of the tree’s crown cover are an indication that the tree is close to death. The time from infection to death is variable and can be anywhere from one to ten years, with larger trees lasting longer than their smaller, younger counterparts.

The lack of visible symptoms is perhaps the most dangerous aspect of the disease. Humans are the primary distributors of the kauri dieback. Unable to detect infected trees, any tramper or hunter who has wandered off the track has no way of knowing if any deadly microbes may have hitched a ride on their boots.

Once relocated to new soil, tiny spores are dispersed and are able to sense kauri roots and swim towards them. Moving contaminated soil to different areas can create entire new sites of infection. But it is not just individual kauri that will face elimination, P. agathidicida has the capability to destroy many other species who rely on kauri as the heart of the forest.

Read the rest of the digital story here.

Tess Tuxford is completing a Master of Science in Society at Victoria University of Wellington. This article was written as part of SCIS 410 – Science Communication and is presented within Shorthand, courtesy of the Shorthand for Education programme.

Featured image: Bush scene, 1919, Auckland, by Charles Blomfield. Purchased 1972. Te Papa (1972-0024-6)