Page 2 of 2

Re: Multi-stem Trees - Measuring Circumference

PostPosted: Wed Jan 25, 2017 10:37 pm
by Will Blozan
Great discussion.

More than one stem at any height means more than one effort to create wood for the organism.

The height may be the key as Darian suggests.


PostPosted: Wed Jan 25, 2017 11:02 pm
by Don
Darian Copiz wrote:Although the examples I've seen appear to be pretty clear to me and I'm not sure why there is so much debate about this, I think there are some potential complications if one is using the root collar for determination, as that area can be somewhat muddled. At 4.5 feet above the ground there is less room for interpretation and things are even clearer. Breast height is where circumference is measured, so that should be where the number of trunks should be determined. Otherwise we might as well measure circumference at the root collar.

Are we not approaching a circular argument?  When you say "Breast height is where circumference is measured...", Breast height is measured FROM the perceived location of the root collar (the proverbial positioning of the original seed that set it all in motion).  
The point is, physiologically, a seed sends up a single meristem. Whether or not it chooses to subsequently branch in response to its new environment is another issue. Those  that retain a single stem form get measured 4.5' up from that 'seed'; and if the seed branches before 4.5' in height, the multiple stems get measured at 4.5', then get 'normalized' to achieve parity with single-stem contenders. This is fair to both single and multiple stems, and serves as a intermediate step in using 'volume' as a measure of bigness.
This 'normalization' method is sound, and we'll soon be sending out a package for all National Cadre Members that will include, among other items, the Normalization Formula and it's derivation, and an Excel spreadsheet that automates the calculations.

I meant to introduce the "after" image of the Quad Sugar Maple which was felled a few years after the "before" image...the attached image is of it's cross-section, very near ground level. For scale, note the 8" x 11" sheet of paper in the middle of the cross-section.  I've copied it below at the highest resolution I can, you should be able to zoom in far enough to discern multiple 'meristems'/piths, at (or very near) ground level...I can't see them coalescing into a single stem maple within inches further down...methinks this was a cluster of four to five maple seedlings planted together to insure at least one came doesn't take much imagination to see the 'before' image looking evermore AS IF IT WERE a single stem tree that has inosculated its own base, had it lived another hundred or two years.

Does it matter? That is the question we have before us, to arrive at a consensus...may the discussion broaden and continue...: > }  [Including the role of measuring girth at breast height!] As Bob would say, we're about to cook with gas!
Quad Sugar Maple Cross-section

Re: Multi-stem Trees - Measuring Circumference

PostPosted: Mon Feb 06, 2017 12:35 pm
by dbhguru

  We continue working on methods for computing a functional circumference to compensate for abnormal or atypical forms of tree trunks. Our primary purpose is to support the champion tree programs, state and national.

   One approach that Don Bertolette and I have been pursuing for literally months is to investigate methods for computing circumference at 4.5 feet based on the form of the trunk above that level projected down to 4.5 feet. This approach can only logically be applied to compliant trunks that show a predictable taper. The attachment offers computational algorithms. It is by no means a panacea - just another tool in the toolkit.

  Both Don and Jared Lockwood are testing the methodology provided in the Excel workbook. They will  project the circumference at 4.5 feet using trees that are "well behaved." If the Excel models hold up, then applying at least one of them to trees with distorted shapes at 4.5 feet would seem to be justified. After cataract surgery in both eyes this month, I'll join the testing. Anyone out there in NTS land who would like to join in either with criticisms or helping us test these models, we would be most appreciative. For those of you who have endured my spreadsheet solutions, you'll note that there is usually an introduction followed by a spreadsheet calculator. I usually include the development of any formulas somewhere in the process. In this case, I've eliminated the mathematical derivations and just presented the final formulas. If anyone wants the derivations, let me know.

 As some final observations, in the past NTS was the vehicle for developing and applying better tree measurement methods for circumference, height, crown spread, and to a lesser degree, trunk volume. Through our efforts, we have worked our way into a position of importance with American Forests (Measuring Guidelines Working Group and Cadre) and now with the VA Tech Dendrology Dept. Most of our more technical efforts will be expressed through the latter two organizations, but the crucible from which idea spring will likely continue to be NTS.