Accurately Measuring the Height of (Real) Forest Trees

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edfrank
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Accurately Measuring the Height of (Real) Forest Trees

Post by edfrank » Tue Mar 18, 2014 9:00 am

Accurately Measuring the Height of (Real) Forest Trees
by Don Bragg

Journal of Forestry 112(1):51-54
http://dx.doi.org/10.5849/jof.13-065
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Bragg2014D.pdf
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"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky

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Don
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Re: Accurately Measuring the Height of (Real) Forest Trees

Post by Don » Thu Mar 20, 2014 1:33 pm

Good catch Ed, I had been sent the URL just a week ago and was pleased to see NTS mentioned...we're gaining momentum!
-Don
Don Bertolette - President/Moderator, WNTS BBS
Restoration Forester (Retired)
Science Center
Grand Canyon National Park

BJCP Apprentice Beer Judge

View my Alaska Big Tree List Webpage at:
http://www.akbigtreelist.org

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edfrank
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Re: Accurately Measuring the Height of (Real) Forest Trees

Post by edfrank » Thu Mar 20, 2014 9:11 pm

Don Bragg sent me the article and I should have credited him as the source for the article I posted.
"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky

Joe

Re: Accurately Measuring the Height of (Real) Forest Trees

Post by Joe » Fri Mar 21, 2014 4:56 am

Don wrote:Good catch Ed, I had been sent the URL just a week ago and was pleased to see NTS mentioned...we're gaining momentum!
-Don
I read the article in the Journal- but I didn't see any mention of NTS- maybe I missed it.
Joe

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Re: Accurately Measuring the Height of (Real) Forest Trees

Post by Don » Sun Mar 23, 2014 2:17 am

Joe-
Bottom of first page (p.51), read Acknowledgements:I recognize the contributions of the Native Tree Society for their efforts to develop and promote the sine method...
-Don
Don Bertolette - President/Moderator, WNTS BBS
Restoration Forester (Retired)
Science Center
Grand Canyon National Park

BJCP Apprentice Beer Judge

View my Alaska Big Tree List Webpage at:
http://www.akbigtreelist.org

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dbhguru
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Re: Accurately Measuring the Height of (Real) Forest Trees

Post by dbhguru » Tue Mar 25, 2014 12:01 pm

Hi All,

Ed's recent post of Dr. Don Bragg's excellent SAF article on the history of tree height measuring focuses attention on the degree to which tangent-based height measuring has understandably dominated the craft over the decades. In the past, they didn't have devices to directly measure distances to the target. One formula that Don cites that was devised to allow the measurer to use slope distance to the trunk instead of horizontal distance. The formula set me to thinking. Here is a derivation.
Screen Shot 2014-03-23 at 5.04.35 PM.png
Note the use of angle A4, which is not directly measured, but computed as the complement to A1. Thus, we see the usual assumption of verticality of the top over the base. It isn't that the early mensurationists didn't understand the assumptions behind their models, I think they just didn't see any simple way around making those assumptions for measurers in the field. Productivity has always been uppermost in their minds. But in time methods become codified and ingrained and woe be unto the outsider who dares challenge orthodoxy - especially within academia. It matters little if we are dealing with astronomy, physics, or forestry. Human nature is human nature.

Don and I are currently working on Webinar presentations on tree height, girth, and crown-spread to be provided by American Forests on May 20 (height), May 27 (crown-spread), and June 3rd (girth). I'll be presenting the first two. Attached is a draft of the PowerPoint crown-spread presentation. Any observations that my fellow and lady Ents would care to offer would be most appreciated. Remember that I'll be talking as these slides are presented. The viewer won't be hit by them cold turkey. The last series of slides will be pitched more as an example of what can be done as opposed to what AF expects to be done. I seriously doubt many measurers will use the method, but it is perfectly legitimate and has a place, however limited, in the repertoire.

Bob
Attachments
AFWebinarCrown-Spread-2.pptx
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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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