Category Archives: Uncategorized

Introducing the kauri drought experiment

KDE logo - 300 dpi web-01

I’m super excited to reveal my new project logo designed by the amazingly talented Josie Galbraith.  Thanks Josie for creating such a beautiful visual to represent my work. And now, it’s time to science!


New blogging home

Ecology Ngātahi is the new group blog I’ll be contributing to. Regular posts will also be written by my colleagues Jacqueline Beggs, Mick Clout and Margaret Stanley.  Moving forward, I’ll be doing most of my blogging on Ecology Ngātahi so head over there for a range of pieces on ecology interconnections.

The Paturoa Kauri FAQ

On Monday morning (9th March 2015) locals, conservationists and tangata whenua gathered at 40 Paturoa Road to protect a centuries old kauri tree marked for felling to make way for new dwellings on the property. Thanks to the efforts of these dedicated folk, the trees are safe (for now). So what is so special about this tree and why should we care about it being removed? Here I address several important questions about the value and significance of this tree and the surrounding vegetation.

Why are kauri trees so special?

Kauri are amongst the largest and longest-lived trees in the world. Tree enthusiasts travel from across the globe to see these majestic plants. Kauri have a special place in Maori cultural heritage because they are taonga species. They have an important role in the spiritual beliefs of tangata whenua and are viewed as chiefs of the forest and a living connection to ancestors. They produce beautiful wood that has been used to build houses, boats and carvings and kauri gum was used to make carvings, glue and other products. Sadly, their wood is so prized that around 95-97% of kauri was cleared after European settlement. Kauri are now protected but the new threat of kauri dieback is threatening the remaining individuals.

Is it really 500 years old?

The age of the tree appears to have been estimated. We can estimate the age of a tree using two approaches. The most accurate approach is to count the annual rings accumulated in the trunk as the tree grows. We can also measure the diameter of the trunk and estimate tree age. For some tree species, this has been shown to be a very effective approach but for kauri, it can be inaccurate because there is only a weak relationship between tree age and trunk girth. That said, it is highly likely that the tree is several centuries old. A tree of this size and age supports a range of epiphytes, lichens and mosses in its branches and is therefore valuable habitat for other species. It also stores vast amounts of carbon and is important for binding soil and modulating the water cycle. No matter the age of the tree, it is ecologically significant.

What about kauri dieback?

The Paturoa Road area is known to be heavily infected with kauri dieback with a number of confirmed cases of diseased trees. Reports about the tree in question suggest that it is currently healthy. A well tree in a diseased area may have some form of resistance and therefore has increased ecological value. The tree may be a vital resource for the Scion Research programme looking for resistant trees. If the tree is infected with dieback and is yet to show symptoms, the removal process and management of the site during the building process must consider biosecurity. The pathogen causing kauri dieback is transported in soils and if wood and equipment are not properly disinfected before entering and leaving the site, the pathogen will be further spread. It is not clear if biosecurity tests have been done at the site to check for kauri dieback. This is a vital step, even if the tree was removed.

What has gone wrong here?

Without knowing the internal processes in council, it’s hard to know why this tree has been approved for removal. It is clear that the current legislation is not protecting valuable trees. Where kauri are involved, there should be mandatory biosecurity checks to make sure the site is correctly managed to prevent spread of kauri dieback. Reports suggest there was no iwi consultation. This is unacceptable given the spiritual significance of kauri. Titirangi is famous for its leafy environment and local residents clearly treasure their forest and trees. There needs to be better protection of this unique and beautiful part of Auckland for everyone to enjoy.

What about the rimu?

Other trees and vegetation, including a 300 year old rimu will also be removed from the site. This is also unfortunate but rimu are not currently threatened by dieback. It would be nice to conserve the rimu too but building on bush land will always require the removal of some plants.

The final word

All kauri are living national treasures. In Europe, centuries old buildings are carefully preserved and protected. We don’t have that type of architectural heritage but we do have a rich natural and cultural heritage that forms part of our identity. This heritage must be conserved for the benefit of future generations. Tane Mahuta will not live forever and this tree may be the largest tree centuries from now. In the context of kauri dieback, this tree is particularly valuable. Surely with some clever design, this tree can be saved for future generations. If nothing else, the tree protection laws need to be reconsidered.

My dirty secret about my latest paper

I have a dirty secret. Actually, it’s not a secret because it’s on twitter which is a public forum so everyone can see it. But I do feel kind of grubby about it and I’ve just worked out why. Last Thursday, I sent this tweet –

Ten lovely people obliged (thank you for playing along @benbondlamberty, @TimCurran8, @PhilJ_Rose,  @HelenWNathan, @PPUAMX, @jcusens, @jmrbrock, @SarahTheWise, @turtleandweasel, @ju*ka, you guys rock) and now my paper is ranked 3rd of 172 for the journal Plant Ecology. I think it’s an important paper because it shows litterfall increases significantly in kauri forest under severe drought. However, I am well aware that I’m completely biased and we haven’t really made any major scientific advances with this work. So now I don’t feel right about manipulating altmetrics scores. As part of this process, one of the retweeters contacted me (probably tongue-in-cheek) and suggested I should tweet about his paper. So I had a look at it and wrote this –

It’s been retweeted 13 times. So for one retweet, my friend has my tweet plus 13 retweets contributing towards his altmetric score. I’d like to think it was my witty take on his paper that scored the retweets. Reality is, it was the universal appeal of their findings. This paper was already in the to 5% of all papers with altmetrics scores so had already proven it’s worth.

I guess that’s why I feel kind of wrong about what I did. Something with wide appeal or super cool results will get attention without the author being so overt. I’m not convinced I have the 3rd best paper in this journal but I do know I have a few fun friends on twitter. I don’t think I’ll be so bold about asking for retweets again. I’d be interested to hear your thoughts on this?

For more on altmetrics and what they tell us, check out this post on the Wiley Exchanges Blog.

And find further reflections on social media stats here.

The value of trees – our Wynyard Quarter project

What do urban trees do for us and how much are they worth? Trees provide a variety of ecological services. They store carbon, improve air quality, control stormwater and make us feel happier. Find out more in an interview with Simon Morton on This Way Up (click on the Value of Trees podcast link) from 16th August at Auckland’s Wynyard Quarter urban renewal area. Our microclimate project appears at about the 9.50 mark.

Willis Bond appointed as residential developer for Wynyard Central

Image from


This is the website of Cate Macinnis-Ng’s lab in the School of Environment at the University of Auckland.

New Zealand’s vegetation is unique with 80% of plant species occuring nowhere else in the world. We are looking at the impacts of climatic conditions on plant functional processes like water use and carbon cycling. We use field, experimental and modelling approaches to explore how plants respond to environmental conditions like soil moisture, rainfall, light availablilty and atmospheric evaporative demand.

You can find Cate’s university website here.