Mark Rauschkolb wrote: MR> Thank you to all who answered my last post asking for references about MR> stem analysis. I have gotten all of the articles that I have been able MR> to find locally, but after reading them, I still do not feel that I MR> have a grasp of what stem analysis actually is (I'm missing the details) I'm not a forester as such, as I have "only" a computing/math education. Still, I have been working in forestry for 6 years, so my following comments aren't totally without a clue. :) MR> Most of the first samples are taken at chest height / 4.5 feet. MR> What is the significance of chest height / 4.5 feet? I think it is just a convenient height that: - is above butt swell, - everyone can measure diameter at this height, and - it is above the height of most competitive brush, so that the tree is well established. In metric, we use 1.3m, rather than a direct conversion to 1.37m. MR> Is there a "standard" distance to be maintained between samples? MR> If not, what determines how often the samples are collected? MR> MR> Once the samples are collected, does what is analyzed vary according to MR> what the individual researcher is studying? Several people where I work have done stem analysis many times. I think they take ten detailed measurements of diameter outside bark. But aside from that, the level of detail of dissecting the trees will definately depend on what they are analysing. They will usually split each log, and identify exactly where the "pith nodes" are, at least for the species where this is possible. They want to know how the tree grew to where it is now. For the most part, the stem analysis we do is to calibrate a tree growth model. We typically choose open-grown trees, so that we can model the extreme condition of unrestricted growth, both up and out. >From the stem analysis, they will create various equations to model height growth, ring width, basal area increment, crown shape, etc. In one case, a researcher spent many months measuring branch angles and foliar volume. Now that I've said all that, I'll step back again, and let the *real* foresters correct any points that I may have gotten wrong... --- Ken Polsson - Stand Modelling Analyst - BC Ministry of Forests --- --- kpolsson@galaxy.gov.bc.ca --- "The opinions expressed --- --- CompuSpec BBS (604)479-0418 --- here are not necessarily --- --- RelayNet: ->1797 --- the views of my employer." ---
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