SAVE OUR TREES

Recently, the remaining kauri have been under threat from the pathogen Phytophthora agathidicida, known as kauri dieback. The pathogen attacks the tree’s ability to absorb water and nutrients from the soil. Symptoms include root rot, yellowing of leaves then defoliation, bleeding resin, and ultimately death of the tree. Although kauri dieback had been identified in Great Barrier Island in the 1970s, it was first noticed as a condition of concern in 2006 in the Waitakere Ranges. Since then, scientists have been desperately researching the disease to understand it and how kauri can be treated. Although dieback affects all kauri in New Zealand, Auckland has been the centre of this research, with Dr Nick Waipara and the late Dr Ross Beever important contributors in this field. 

The pathogen can spread on just a pinhead of soil, making humans one of the biggest spreaders of the disease. Approaches to stop the spread have included track closures and an emphasis on getting track users to clean their footwear. One important aspect is raising public awareness and understanding of the disease. Kauri are a keystone species – many other species have evolved around them, so their loss would significantly change the ecosystem. 

Due to the tiny size of the pathogen, one of the main ways it is spread is by people with infected soil on their footwear travelling to forested areas with kauri. Those studying the disease have noted that the majority of infected trees are in close proximity to walking tracks, which is why it is very important to stay on the tracks. Another way for the public to help stop spreading the disease is to ensure footwear is thoroughly disinfected. 

The brush and trigger spray bottle shown here were part of the efforts by Keep Kauri Standing (now Tiakina Kauri) to spread awareness of the need to clean footwear. Initially, barrels of disinfectant with brushes and spray guns were installed in popular tracks, but these had limited public uptake. 

The Department of Conservation (DOC) contacted Mike Williams of industrial design firm MWDesign to come up with a solution which would encourage users to engage with the cleaning system. MWDesign developed cleaning stations with a combination of fixed brushes and a pressure-activated pad which mists the foot with the disinfectant solution. Dirt and particles drop below the unit into a reservoir which instantly kill any pathogens. MWDesign is continually evolving the cleaning station design to respond to the needs of DOC and the councils who use the units. In 2022, MWDesign donated one of their 2019 prototypes to Auckland Museum. 

In addition to the threat posed by kauri dieback, urban kauri on private land can still be chopped down by landowners. Changes in 2015 to the Resource Management Act removed blanket protections for urban trees and the removal of kauri is permitted under the Auckland Unitary Plan. Prior to 2009, native trees over a size threshold were protected by default and needed resource consent to be removed, but there are now very few protections to prevent private landowners from chopping down trees on their property. 

Auckland has an average tree cover of less than 20% so the felling of urban trees continues to decrease this. Erosion of laws to protect urban trees has led to the felling of prominent trees, which has in turn led to protests drawing attention to this issue. Awhiawhi, a 350-year-old kauri in Titirangi, has been threatened by developers since 2015. The tree has survived so far due to vehement public protest, but still has no legal protection.