Joint effort to save beloved kauri
Citizens and scientists are working together to help the might taonga tree which is under threat, writes Andrea Byrom.
Two weeks ago, I wrote about how the National Science Challenges were born out of the Great New Zealand Science Project, a public campaign that asked New Zealanders to help identify big issues facing the country that science could help solve.
National Science Challenges are funded to solve big, complex and long-term problems.
This week we look at kauri dieback disease, a pathogen that has a devastating impact on this much-loved taonga. The disease is spreading quickly, and could even cause localised extinction in parts of the Waitakere Ranges in Auckland. Two new science programmes funded in Biological Heritage National Science Challenge bring together citizen science approaches and fundamental science to tackle kauri dieback disease.
Community control of kauri dieback
‘‘A biosecurity team of 4.7 million’’ is the first of five strategic goals recently released by the Ministry for Primary Industries. This new programme aims to enlist the public’s help in dealing with the threat posed to kauri.
Kauri dieback disease has already killed hundreds, or perhaps thousands, of kauri trees in the North Island. New Zealanders have strong emotional and cultural attachments to kauri, and their loss is having a major impact. The mighty kauri is symbolic of strength and longevity, and a legacy of our Gondwanaland heritage.
At a practical level, there are significant concerns about harm to people and property from dying trees, and the substantial costs (in the $1000s for just one tree) of felling, and disposing of diseased trees on public and private land.
The fungus-like disease was first identified in the 1970s on Great Barrier Island. In the last 10 years, it has been found in many mainland forests and has become a serious problem. The Waitakere Ranges, west of Auckland, are a particular hotspot. The most likely way of it spreading is on the bottom of our shoes, and through moving plants and soil around.
Under this project, a team from Plant & Food Research will develop a programme to enable scientists, communities and mana whenua to work together on the remedial treatment of kauri trees, otherwise doomed to die.
Of the control tools investigated to date, phosphite injection treatment is the most thoroughly studied and promising, but it may still be some time before research is completed.
So in the meantime, participants in this study will apply treatments under strict protocols so scientists can properly measure their efficacy and possible side effects. Research is already under way with a preprogramme survey to find out community attitudes and responses to the trees, the disease and treatment options.
Stopping kauri dieback in its tracks
This programme, led by the University of Otago, will use a combination of biochemistry and matauranga Maori (Maori knowledge) to try to foil the spread of kauri dieback. The pathogens that cause kauri dieback are problematic worldwide. Another form of the pathogen caused the Irish potato famine, and yet another is attacking many Australian native flora as well as avocado trees.
A major way in which kauri dieback disease spreads is by freeswimming zoospores in soil. Zoospores are reproductive spores with long rudder-like flagellae (or tails). The spores can swim through waterlogged soil at amazing speeds for a tiny organism: nearly 1 metre an hour. Once they find their target kauri roots, they initiate an infection that eventually starves the tree to death.
So, what is it about kauri roots that attracts the zoospores? These spores seem to find the smell of kauri as alluring as the smell of coffee is to humans. The Otago team, with colleagues from Lincoln University, will identify the chemical signals from kauri and other native plants that attract, repel or disrupt the ‘‘homing’’ ability of zoospores – and they will then test the effect of these compounds on the movement of zoospores through soils.
The overall goal is to provide new tools to protect New Zealand’s kauri forests. For instance, zoospore repellents could be applied around kauri trees to deter spores, and in the long term, the general principles of the research may also be applied to the battle against other plant pathogens.
A nature forecast
Eventually the hype around kauri dieback will die down and some other crisis will capture our attention. How can we keep New Zealand’s environmental problems front and centre in the public mind?
What if we had a ‘‘nature forecast’’ on national television every night, and paid it the same level of attention we pay to stock market fluctuations or the weather forecast?
Perhaps if we were all more aware of the threats faced by so many of our native plants and animals, such as the mighty kauri, we would be more likely to encourage politicians to do something about them. ❚ Dr Andrea Byrom is the Director of the Science Challenge for New Zealand’s Biological Heritage, and is an expert in the management of predators such as possums, rats and stoats.