The Kauri (Agathis australis) is something special. I’m from down south, not from Kauri tree territory (the north of the north island) so they are something new and different for me. I’m amazed at how huge they can get, and how long they can live for. Kauri can grow over 50m tall, can have a trunk circumference of up to 16m, and live for over 2,000 years. We humans can probably only muster 120 years maximum, and much less than that if our trunk circumference gets to a more than 80 or so centimetres, putting us at risk of heart disease and various other health issues. Longevity-wise and biomass-wise we are insignificant in comparison to those mighty trees!
However, things are not well in Kauri-land. You don’t have to go too far from the central city to see dead Kauri in the bush, and other Kauri trees with canopy thinning, and branch dieback. This death and destruction is the result of a disease known as Kauri dieback. It is caused by a microscopic fungus-like organism called Phytophthora agathidicida or PA for short. PA lives in the soil and can infect tree roots. PA can be easily spread through an area if soil is moved around, for example by animals, on shoes, on vehicles etc. Once the organism infects kauri roots, it starts damaging the tissues that carry nutrients and water within the tree, gradually killing the tree essentially by starving it to death. Currently there is no cure, and nearly all infected trees die. According to the former head of biosecurity at Auckland Council, kauri dieback is like HIV and Ebola (for trees) rolled into one.
While there has been some success in keeping young infected kauri alive by injecting them with a chemical called phosphite, there currently is still no known cure. From what I have read, kauri dieback has become a political football with some scientists blaming the Ministry of Primary Industries for a lack of research co-ordination resulting in the continued spread of the disease. I hope the politics doesn’t mean that the spread of kauri dieback cannot be stopped. We probably should all be staying out of the bush to reduce the chances of soil disturbance thereby reducing the spread of PA, but if you are thinking of heading anywhere near the bush, please make sure to:
· Stay on the track, and only go to tracks that are still open. (If in doubt, check with DOC or local council websites)
· Clean your footwear and gear completely every time you enter or leave an area with native trees. Get rid of all soil on your gear – the tiniest pinhead of soil can contain PA, so leave the soil behind where it came from.
· Disinfect you gear after you’ve removed all the soil.
· Spread the word – tell others what they need to do to protect our wonderful trees!
https://www.doc.govt.nz/nature/pests-and-threats/diseases/kauri-dieback/
https://www.kauridieback.co.nz/
Can we fix it? How the King of the Forest, Tane Mahuta, is being kept alive
Science Scholars 2019 