Now that's a big tree!

VulcanSpirit
Richard & Alison Brunstrom
Tue 19 Feb 2013 10:11
Here it is:
 
 
It may not look like much, until you spot Alison's head in the undergroth at the bottom of the trunk. This is Tane Mahuta, the Lord of the Forest, the biggest kauri tree in NZ. NZ kauri are Agathis australis (australis means 'southern' in Latin) to distinguish them from the other Agathis species which live in Australia and SE Asia. It is a NZ endemic. They are closely related to the monkey puzzle tree familiar in UK gardens (it actually comes from Chile) and is yet another example of things that evolved in Gondwana more than 70 million years ago. Tane Mahuta is around 2000 years old and has a total wood volume of over 500 cubic metes, making this the third biggest tree species in the world after the North American redwoods Sequoia and Sequoiadendron. Very much bigger kauris are known to have been cut down, and Tane Mahuta is still actively growing so perhaps in another thousand years he'll rival the redwoods.
 
Kauri forests once covered a vast tract of NZ's North Island, but tragically they were almost all cut down in a frenzy during the 1800s - the unique growing style with the huge straight branchless trunk providing outstanding knot-free timber. Only tiny fragments remain.
 
Kauri start life looking completely different. Here's a baby, with a conical crown:
 
 
 
And here are some young adult trees, before the huge trunk and giant splayed crown develop:
 
 
These are still tiddlers, but for scale note the people passing below.
The remaining kauri forests are reserves, but the kauri are not out of the woods yet (couldn't resist it). Worryingly, mature kauri are dying of 'kauri die-back disease', a fungal infection. Kauri roots are shallow and delicate. It is now realised that humans trampling round the trees can wound the roots (they evolved in the total absence of heavy footed animals) allowing fungus to enter - and human feet are transporting fungal spores from one forest to another. So now access to kauri reserves requires footwear to be washed on entry and exit, and you can only approach the trees via boardwalks and prepared paths. 
 
Kauri are a national treasure, and the few remaining forest fragments truly astounding places. I hope they survive.