Modeling a 117 foot, 234 point poplar in Chapel Hill, NC

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pdbrandt
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Modeling a 117 foot, 234 point poplar in Chapel Hill, NC

Post by pdbrandt » Tue Dec 27, 2011 11:55 am

[Ed and Bob, I’m not sure whether this post is more appropriate here or in the “Measurement and Dendromorphometry” section. Please feel free to clone or move the post as needed. ]

Dear NTS,

Carolina North Forest (CNF) is a 760 acre public use forest maintained by the University of North Carolina. The forest cradles a soon-to-be-defunct airstrip used over the years by the rich and famous of Chapel Hill as well as visiting dignitaries. CNF is crisscrossed by miles of dual use running/hiking and mountain bike trails. The forest is primarily composed of ~50 foot tall new growth loblolly pines, but there are a few pockets of mature deciduous stands as well, with multiple trees over 100 feet tall. The forest is loved by the locals and even has its own facebook page (http://www.facebook.com/pages/Carolina- ... 4238759273).

CNF is on my commute to and from work and I have spent many hours riding the trails scouting for big or otherwise notable trees. The monarch of the forest is a tulip tree (Lirdiodendron tulipifera) with a CBH of 8’, 10” that towers over a section of the forest noted for its lack of undergrowth, but plentiful, straight-boled poplars, gnarly oaks, and sweet gum trees. Last Thursday I set aside most of the day to climb the monarch with the purpose of determining the height and total volume of the tree.

This is my first attempt at determining total tree volume and part of the purpose of posting my experience and my data set is to get your feedback about whether I am making correct assumptions and modeling the tree in an accepted way. I plan to model at least one other tulip tree in CNF – a wish bone poplar with a CBH of 11’, 11” (the trunk diverges at 5.5 feet high into 8’, 4” and 6’, 11” co-leaders), and one or more of the giant red oaks that watch over another part of the forest. I appreciate any comments, questions, or suggestions you can offer.
The Monarch of CNF
The Monarch of CNF
The monarch poplar is about a half mile from the trail head so I tried to pack lightly. Even so, I got some quizzical looks from trail runners as I toted my harness, ropes, slingshot and climbing helmet through the forest. The climb took place on the first day of winter, but the temperature was a balmy 65 degrees and I left my jacket at the base of the tree. I had previously measured the CBH to be 8’, 10” (or 106”) and the average spread of the compact canopy at 43’, 6” (45.5 feet major axis and 41.5 feet minor axis). Apparently, luck was on my side because I set an entry line over a good branch 65 feet high on the first try with my hand held slingshot.
Light weight tree entry option
Light weight tree entry option
The modified slingshot is made by attaching a $30 spincast fishing reel (spooled with 90 yards of 20 pound test line) to a $15 wrist rocket slingshot using a short piece of PVC and 2 hose clamps. A 2-ounce lead weight wrapped in bright orange duct tape serves as the projectile. I use the fishing line to haul a 2.2 mm throw line over the branch and then use that to place my 11.5mm arborist rope over the limb.
The Monarch's crown
The Monarch's crown
I climbed to my first tie in point using a split tail, doubled-blake’s hitch, self-advancing setup and a single foot lock. I stopped every ~15 feet to measure the circumference of the trunk on the way up to the first branch. At 50’ up, the trunk was still 6’, 10” in circumference. The first two branches are at 54 and 59 feet high and appear to have been broken off by storm damage. I measured the limb circumference of these and all 15 primary limbs that protrude from the trunk. Limb circumferences range from 18 inches to 38 inches. The main bole splits at 71 feet into a 4’, 11” circumference leader and a 3’, 11” lesser trunk. The leader was still 2’, 5” in circumference at 94’ when it finally split into a series of secondary branches that I wasn’t comfortable trusting my life to.

I brought along a new tree climbing tool that proved worthy of its weight many times over. It is a set of 11 aluminum tent poles shock corded together that telescopes out to a little more than 16 feet long. The whole set weighs about 10 ounces and fits in an old umbrella cover that hangs from my climbing saddle. I used the poles, which have bright orange tape at 1 foot increments, to determine the length of secondary branches too steep or too flimsy to access. The poles, which have a hook on one end, also come in very handy when advancing my climbing line when the dangling end of the rope is out of my reach. (Incidentally, I bought more than 11 poles from http://questoutfitters.com/tent_poles.htm, but I found that combining any more than 11 sections results in a pole that curves too much to be useful.)
poles extend to 16 feet to help with measurement or line retrieval
poles extend to 16 feet to help with measurement or line retrieval
While tied into the crotch at 94’ feet high (confirmed with a final tape drop), I extended the 16-foot pole as high as my arm could reach, but the tip was still about 2 feet shy of the tallest twig. Adding a few measurements together I confidently report the height of the tree as 117’ (+/- 6”). There are most certainly many taller tulip trees in NC, but this one is certainly one of the tallest in CNF and a worthy specimen for the central Piedmont of NC. With a height of 117’, CBH of 106” and average crown spread of 43’ it has AmericanForest.org point value of 234.

I calculated trunk section volumes using the formula for volume of a frustrum (Vol=pi*h/3*(R^2 + Rr + r^2). I made 11 trunk circumference measurements between ground and 94’ high and I also treated the two lowest branches (the broken ones) as frustrums. There was also a primary limb at 61 feet that split into two limbs 5’ from the trunk and I treated the single section close to the trunk as a frustrum as well. All frustrum sections together represent a volume of 391 cubic feet.

I made some assumptions when calculating the volume of the primary branches. As noted above, there are 15 primary limbs that protrude from the trunk with circumferences ranging from 18 inches to 38 inches. I measured/estimated the length at which each primary limb tapered to less than 2 inches in diameter by cautious limb walking and using my extendable pole. Limb lengths ranged from 15’ to 35’. To calculate volume of the primary limbs I determined 3/4 of the starting radius and assumed that represents the width of the limb at 1/2 way out the branch. I used the equation for volume of a frustrum to estimate the area of the first half of the limb. I treated the remaining branch as a cone (vol=pi/3*r^2*h) with radius determined in the previous step and “height” equal to half the length of the limb. All the primary limbs calculated in this fashion represent a volume of 59.5 cubic feet (16.5% of the volume of the trunk sections). My calculations are shown in the attached spreadsheet with more details in case your interested and my explanation isn’t clear here.

I took notes on how many secondary limbs greater than 2” in diameter extended from each primary limb. In cases where a secondary branch was much bigger than 2” in diameter I counted it as 2 or 3 branches to simplify calculations. When I added all the secondary branches together the number came to 99. I assumed that each branch was on average 10 feet long, 2” in diameter, and behaved as a simple cone. Calculating the volume of the secondary branches in this way added 7.2 cubic feet to the total tree volume.

To summarize the volume measurements, the trunk sections, primary limbs, and secondary branches greater than 2” in diameter represent 391, 59.5 and 7.2 cubic feet for a total of 427.7 cubic feet. When compared to the monster tulips of Great Smokey Mt National Park like the Sag Branch Tulip (4013 cubic feet) or the Fork Ridge Tulip (http://www.ents-bbs.org/viewtopic.php?f=74&t=2423, 2844 cubic feet) measured by Will Blozan et al, the “Monarch of Carolina North Forest” seems positively diminutive. Hopefully, I’ll get the chance to help measure one of the real monarchs some day.

This tree houses many different lichens and mosses as well as a family of squirrels. While aloft, I saw a large hawk (red-tailed?) silently glide by and land in the tree next to me. A moment later another hawk landed gracefully in another nearby tree. Both either didn’t see me (not too likely) or didn’t care that I was there (the ultimate compliment). It was fascinating to watch as they ruffled and preened themselves, and then a moment later, both flew off for other parts of the forest. That experience typifies what I love about climbing into the canopy – experiencing the forest ecosystem from a different perspective where I can almost convince myself I belong.
closeup of lichens and moss
closeup of lichens and moss
View from the top
View from the top
Last year's tulip shells
Last year's tulip shells
next spring's promise
next spring's promise
The view from the top is spectacular, and in the upper levels of the canopy last year’s tulip shells and next year’s buds can be seen almost side-by-side. There are a few more pictures from the climb at http://www.facebook.com/media/set/?set= ... 241&type=1

Thanks for reading and thanks for helping me hone my volume measurement protocol for future data generating climbs.
Attachments
12-22-2011 tulip volume calculations.xls
(53.5 KiB) Downloaded 107 times
Patrick

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jamesrobertsmith
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Re: Modeling a 117 foot, 234 point poplar in Chapel Hill, NC

Post by jamesrobertsmith » Tue Dec 27, 2011 1:32 pm

Wow. Amazing how you guys get up there in those tall trees! I'd never seen that slingshot rig before. That's a nifty setup!

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dbhguru
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Re: Modeling a 117 foot, 234 point poplar in Chapel Hill, NC

Post by dbhguru » Wed Dec 28, 2011 9:56 am

Patrick,

Welcome to the exclusive club of NTS tree modelers. Outstanding work! I am very impressed with the detail you collected and I love your spreadsheet - very easy to follow. I hope you and Will can team up and climb some of the trees in the Smokies, but it is good to have our tree modelers spread out. We hope you will keep modeling interesting trees.

I note that from experience, single trunk trees in a forest start to stand out around 300 cubes. A 400+ cube tulip does make an impression.

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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edfrank
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Re: Modeling a 117 foot, 234 point poplar in Chapel Hill, NC

Post by edfrank » Wed Dec 28, 2011 2:31 pm

Patrick,

We can have the post in both areas. If I move it from one place to the other I can leave a "shadow topic" behind so that the post ad any follow-up replies appear in both forums. I have done this for most of the Live Oak Project files. Larry posts them to the Live Oak Project and I move them to the proper state leaving the shadow behind in the project forum. It works out fine. This doesn't affect the links themselves as each post has the same url regardless of the forum in which it appears.

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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Will Blozan
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Re: Modeling a 117 foot, 234 point poplar in Chapel Hill, NC

Post by Will Blozan » Thu Dec 29, 2011 5:00 pm

Patrick,

Excellent work! I like your telescoping poles for extended measurements and rope positioning. I have been using a painter's pole with calibrations on it for the terminal lead measurement. And yeah, the sheer size of the giants is mind-boggling when even a 400 cuber looks big!
Sag Branch Tuliptree 2004
Sag Branch Tuliptree 2004
Your post has inspired me to post about a tall but small tree we did a few months ago... coming soon!

Thanks for the post and I hope to join up sometime on a climb. BTW, have you seen the collection of old tuliptrees at Tanglewood Park in Clemmons? Nice, old specimens worth a visit.

Will

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M.W.Taylor
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Re: Modeling a 117 foot, 234 point poplar in Chapel Hill, NC

Post by M.W.Taylor » Thu Dec 29, 2011 9:47 pm

Partick,

Thank you for your excellent report. Fantastic details and pictures.

Michael Taylor

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pdbrandt
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Re: Modeling a 117 foot, 234 point poplar in Chapel Hill, NC

Post by pdbrandt » Wed Jan 18, 2012 9:18 pm

M.W.Taylor wrote:Partick,

Thank you for your excellent report. Fantastic details and pictures.

Michael Taylor
Thank you, Michael. I am humbled by your interest given your life's work scouting out redwoods nearly four times as tall as the tree I described.

Keep up the great work!

Patrick
Patrick

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pdbrandt
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Re: Modeling a 117 foot, 234 point poplar in Chapel Hill, NC

Post by pdbrandt » Wed Jan 18, 2012 9:26 pm

Will Blozan wrote: Your post has inspired me to post about a tall but small tree we did a few months ago... coming soon!

Thanks for the post and I hope to join up sometime on a climb. BTW, have you seen the collection of old tuliptrees at Tanglewood Park in Clemmons? Nice, old specimens worth a visit.

Will
Hi Will, I would love to help with one of your climbs sometime. I'll be out your way around April 18-21. Can I be of help to you during that time?

I haven't been to Tanglewood Park, yet, but it is only an hour from my house. I will definitely check it out.

Have you already posted your "tall but small" climb report? I will be posting another report on a wishbone poplar in the coming weeks. I just wish I had more time to be in the woods!
Patrick

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