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.