Functional circumference exercise

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dbhguru
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Functional circumference exercise

Post by dbhguru » Sat Jul 21, 2018 4:03 pm

Ents,

I’m staying in Crestone, CO and am surrounded by pinyon pines of every conceivable shape. Great opportunity to practice with computing functional circumferences. Taking the circumference below the branching yielded 63 points. Functional circumference gave 53 for the four trunks. But functional circumference circumference could have been done in slightly different ways. One wsy is to set the vertical height above the base at 4.5 feet, pass a horizontal plane through the point and take the cross-sectional areas of the stems penetrating the plane. Area would be taken at 90 degrees to the pith lines. Another method is to follow each pith line individually for 4.5 feet to get to the point where the cross-sectional area is taken. The 4.5-foot path will not necessarily be straight. This is Don’s and my preferred way. The formula to compute functional circumference takes several forms. The simplest is:

C = SQRT(SUM(Ci^2))
6E1C708B-298E-48B6-A679-90B4DA892FEE.jpeg
The challenge with the pinyon pines around our B&B is that a combination of both trunks, limbs, and branches, may be penetrating the horizontal plane at 4.5 feet. Deciding what is a separate trunk versus a limb off another trunk is tricky the closer to the ground you are. We don't have clear guidelines on when to call something a limb versus a trunk. More to come.

Bob
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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Larry Tucei
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Re: Functional circumference exercise

Post by Larry Tucei » Mon Jul 23, 2018 9:58 am

Bob- The Multi- Trunk specimens can be tricky to determine what is a limb and what isn't. Larry

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mdvaden
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Re: Functional circumference exercise

Post by mdvaden » Mon Jul 23, 2018 10:40 am

Larry Tucei wrote:Bob- The Multi- Trunk specimens can be tricky to determine what is a limb and what isn't. Larry
Actually, I think some of the ENTS folks are just beating their head against the wall on this one. Personally, for a Multi, I'd just modify the rules if it were in my hands. Maybe shove a singe stem competing tree's measure down lower to compare the two. Or add the multi-stem's trunks all together at dbh.

Otherwise, I think the real solution may need input from the scientists who measured the volume of wood and foliage the past decade or two, for giant sequoia, coast redwood, Douglas fir, etc.. I think they could tell how much meat a tree has on it's bones for each reiteration in comparison to various limbs, trunks, etc.. It's possible, some feedback from that could say whether trunk's diameters could all be added, or to try some other option.
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dbhguru
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Re: Functional circumference exercise

Post by dbhguru » Tue Jul 24, 2018 11:14 am

Mario

Consulting Steve Sillett or BVP is fine for the trees they study and measure, but going that route would be a tough sell to the state champion tree coordinators and the national coordinator, none of whom envision a role for heavy science. For single versus multi-stem forms, the functional circumference method does level the playing field somewhat, and it isn't too complicated, at least not to my mind. It also has the buy-in from forest biometricians. That said, Don and I wage a constant battle of wills with our American Forests colleagues, some of whom regard anything that requires even the simplest calculation to be too complicated. Still, we persist. The point isn't for the public to have to use complicated processes, but for certifiers to do a better job. The use of AF measurements for scientific purposes was always a stretch.

If we abandon the champion tree programs, most of these controversies disappear.

Bob
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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