Percent Cylinder Occupation

General discussions of measurement techniques and the results of testing of techniques and equipment.

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edfrank
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Re: Percent Cylinder Occupation

Post by edfrank » Sat Feb 02, 2013 7:42 pm

Michael and everyone else,

Yes I made a math error. I am sure all of you have done the same. I tried to answer the question posed given the limited data I had available. I emphasized that the data I had was limited and might not be directly applicable to this situation. I think the idea is worth pursuing. I don't know what will be found, if anything, but it is worth collecting the data and seeing what it shows.

Ed
"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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KoutaR
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Re: Percent Cylinder Occupation

Post by KoutaR » Sat Feb 02, 2013 8:02 pm

Ed,

Many thanks for the data you provided. I think with your and Will's data we got the best possible answer to my original question. For higher accuracy and reliability, we would need much more measurements of "our" spruce. I did not mean to accuse you of the math error. I make for sure more such errors than you.

Michael & Jeroen, should we actually give a name to the spruce? "Biogradska Giant"? Or can only western real giants be "Giants"?

Kouta

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Michael J Spraggon
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Re: Percent Cylinder Occupation

Post by Michael J Spraggon » Sun Feb 03, 2013 1:02 pm

I agree Kouta. I make errors too - I was just being light-hearted about it!

What to call this tree is your decision of course, being the discoverer. Maybe some reference to the confluence or two rivers?

Michael

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Michael J Spraggon
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Re: Percent Cylinder Occupation

Post by Michael J Spraggon » Sat Mar 02, 2013 11:23 am

I've calculated the cylinder occupation of Long John Silver, a giant Eucalypt that my friend Ben Rose climbed and measured with Brett Mifsud. The tape wrap and height data is here on Brett's website: http://victoriasgianttrees.weebly.com

The volume of 185.8m³ is excluding branches. Height is 81m, cbh (1.4m) is 13.0m. Diameter at 75m is 0.2m so it is pretty much complete.

% occupation is 17.1% based on these figures. However, if we extrapolate the taper from 20.6m to 11.0m above the flared base down to the ground then the girth at ground level would be 7.1m. This gives a percent occupation of 56.8% excluding branches!

This high figure must be related to how fast Eucalypts reach full height. Could it be that the tallest ones have a greater average height of wood above ground level than the tallest Sequoias?

Michael

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KoutaR
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Re: Percent Cylinder Occupation

Post by KoutaR » Sat Mar 02, 2013 12:10 pm

Michael J Spraggon wrote:Could it be that the tallest ones have a greater average height of wood above ground level than the tallest Sequoias?
I can't answer to your question, but "average height of wood" is an interesting measure. "Average height of leaves" would be another - the tallest eucalypts and tropical trees would beat the western conifers.

Kouta

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edfrank
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Re: Percent Cylinder Occupation

Post by edfrank » Sat Mar 02, 2013 1:41 pm

Michael, Kouta,

Could you explain what you mean by "average height of wood"? The meaning is not clear to me.

Ed
"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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KoutaR
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Re: Percent Cylinder Occupation

Post by KoutaR » Sat Mar 02, 2013 4:27 pm

Ed,

I understand it: the height of every piece of wood, and the heights averaged. If we have girth measurements at every 5m intervals, for example, we can calculate the volume of every 5m piece, then calculate (volume * height) for every piece and finally average the values.

"Average height of leaves" similarly.

Kouta

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edfrank
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Re: Percent Cylinder Occupation

Post by edfrank » Sat Mar 02, 2013 4:44 pm

Thanks, I had not heard of the concept. So a tree that retained a nearly cylindrical profile for a greater height before tapering to a pointed top would have a greater wood height? I see.

Ed
"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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KoutaR
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Re: Percent Cylinder Occupation

Post by KoutaR » Sat Mar 02, 2013 4:48 pm

edfrank wrote:So a tree that retained a nearly cylindrical profile for a greater height before tapering to a pointed top would have a greater wood height?
Exactly!

Kouta

fooman
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Re: Percent Cylinder Occupation

Post by fooman » Sat Mar 02, 2013 5:02 pm

That measure of "average height of wood" could actually be done via a 2nd moment of area type calculation. Effectively you are after the centroid of (mass/volume/area). In a perfect cylinder, the centroid would be at half height (from base). For a cone, 1/4 height from base, etc.

Cheers,
Matt
Last edited by fooman on Tue Mar 05, 2013 3:45 pm, edited 1 time in total.

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