Posted: Mon Jan 28, 2013 10:17 pm
by fooman
Interesting stuff Kotua,

I just want to make a quick comment. You stated:

Anyway, most of the biomass is in the tree stems (in the case of the Picea - Tsuga stand 88%), so the stem biomasses should be relatively close to the total biomasses.

In terms of the NZ kauri (Agathis australis), this assumption may not hold true. The only full measurement of wood volume of a large kauri (that I know of) was done by Bob van Pelt on Tane Mahuta in 2002 (and reported here). The stem was 255 m3, total wood volume 516 m3. Almost all other data for kauri volumes is stem or merchantable volume (generally based on cbh, height of bole and a factor for taper - generally between 5% and 10%). This method dates back to the 19th century, and somewhere there is a paper from the 50's or 60's that shows that this tends to underestimate the volume by 5 to 10% when checked by tape-wraps.

Anyway BvP measured ~ 49% of the wood volume in the stem, 38% of the wood volume in the branches, and the remainder (presumably) in the top logs above the first fork. The 255 m3 stem measurement was a little bigger than the official 244 m3 "merchantable" volume that kauri are ranked on. A little over half of the mass of the tree was not in the primary stem.

There is a good photo of the crown of Tane Mahuta at

Another specimen kauri (Tane Moana), approximately 35 ft cbh, with a 25 or 30 ft bole (no offical measurements exist) would have even more than than 50% of its volume in the crown, as shown by a picture of its crown at

The Trounson Kauri park is exceptional, in that it is the best remaining stand of kauri dominated forest. The other large forests containing old growth kauri tend to be mixed kauri/podocarp/broadleaf forests. I've only been there once, in a much younger form, but it always struck me for the density of the kauri crowns emerging from the undergrowth. I cannot find a photo looking over the park, but google street view does convey some of the majesty here: There is a old photo of similar grove, which is a favourite of mine, as it shows a kauri stand, just before it was felled for timber (see attached). Finally, there was a particular tree called the Trounson big tree, but it was not at the park, but named after the person who preserved the park. The Trounson big tree would be one of the largest, if not the largest, if it were still standing, but it burnt down in the first decade of the 20th century. Wikimedia has an image of it, and I have attached it below.



Almost pure stand of mature kauri, before felling, circa 1910.


Trounson Big Tree. ~ 16 m (52 ft) cbh, 13-14 m bole