Proposed Project for Crown Spread

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dbhguru
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Proposed Project for Crown Spread

Post by dbhguru » Wed Nov 06, 2013 8:02 pm

Hi Folks,

Don Bertolette and I need assistance on a project for AF and we hope that our fellow and lady NTS members will lend a helping hand. We have gotten the actual measuring processes under control and we are at a place in the AF MGWG proceedings where we want to seriously review the current AF formula for crowning national champions. We have spent a lot time discussing the formula and alternative approaches, but are now ready to move to the next step.

Proper weighting of the three dimensions to better reflect volume considerations has always been a priority of mine. However, so has consideration of the psychological impact of form on our perception of big. We all want a champion to look like a champion. Plus, we don't want the measuring process or formula to get too complicated. Nor do we want an arbitrarily simple formula that allows obviously unworthy candidates to beat worthy ones. And, we certainly don't want to make changes, upsetting the apple cart, that don't improve things. Lots of balls up in the air. What to do?

We are thinking of developing a dataset of freshly measured trees replete with photographs that compares candidates through the standard AF formula, regular TDI, the unweighted AF formula, weighted TDI, and maybe other formulas. Here is how we see the comparison process working. We would find two trees that score close to one another on one or more of the champion tree formulas. We would score the pair on all the formulas and then present the whole shooting match with photos to NTS members for comments/judgements. Hopefully, other NTS members would follow suit and present pairs of trees for comparison through the different evaluation systems. Where we can get decent volume data, we would include that.

The measuring is old hat. It will be the photography that challenges us. Photographs of two competitors will need to be taken from the same distance and perspective and always with a standard scaling object for comparison purposes. Silhouetted type views will be especially useful where possible.

Don and I have thought of other approaches. For example, we could re-score lots of trees in the AF database to see what kind of shuffling might take place if, for example, the 1/4th weighting of crown spread were dropped. But with the low accuracy level of the measurements for so many trees in the register, what would the exercise prove? We need really good data and good images. It doesn't matter if the two trees being compared are champions/co-champions. We want to see competitors side by side and scored on the competing systems. From their images, we want to see if the scoring makes sense.

Most of us are aware of trees that were crowned on the current AF formula, but were visibly undeserving. Short of doing a very detailed volume modeling, it is seldom clear how we would handle this type of problem through a simple change of weighting. It is going to take a study.

Who is willing to throw in with us and help? It could be a lot of fun.

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: Proposed Project for Crown Spread

Post by Larry Tucei » Thu Nov 07, 2013 1:46 pm

Bob- Count me in and it would be my pleasure to help with this. Larry

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bbeduhn
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Re: Proposed Project for Crown Spread

Post by bbeduhn » Fri Nov 08, 2013 3:56 pm

Bob,
I can help with this project as well.
Brian

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Will Blozan
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Re: Proposed Project for Crown Spread

Post by Will Blozan » Fri Nov 08, 2013 5:34 pm

Bob,

As time permits, I will certainly help out.

Will

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dbhguru
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Re: Proposed Project for Crown Spread

Post by dbhguru » Sat Nov 09, 2013 6:52 am

Will, Brian, Larry,

Thanks. Adding Don and me, that makes 5 of us, so far. I hope more will sign on. I'll start the ball rolling with photos and measurements.

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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Matt Markworth
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Joined: Fri Nov 23, 2012 8:41 pm

Re: Proposed Project for Crown Spread

Post by Matt Markworth » Sat Nov 09, 2013 7:23 am

Bob,

I have a forest-grown Tuliptree in mind that I'd like to compare to an open-grown one. The forest-grown tree sits next to a small creek that will provide an unobstructed camera view for a good distance.

Matt

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dbhguru
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Re: Proposed Project for Crown Spread

Post by dbhguru » Sat Nov 09, 2013 4:55 pm

Matt,

Soooopa! This project could help us revise the basic formula. Don and I are investigating alternative methods for judging champions. I do hope that NTS members realize that we have an opportunity to revamp the national big tree program toward something that make since at a technical level and one that people intuitively see as fair. But Don and I have to do our home work. American Forests has been around since 1875 and is the oldest national conservation organization in the nation. The National Register, despite its resent short comings, is loved and there are movements world wide to adopt its general form. So, if we can make improvements, the impacts will go very far.

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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Matt Markworth
Posts: 1302
Joined: Fri Nov 23, 2012 8:41 pm

Re: Proposed Project for Crown Spread

Post by Matt Markworth » Sun Nov 10, 2013 9:20 pm

Bob,

I measured two Tuliptrees today for comparison, one forest grown and one open grown. Here are the numbers:

Forest Grown
Ht: 140.9' (Nikon 440/clinometer)
CBH: 86"
Avg Spread: 43' (AF Method)
Ht to First Branch: 84.1' (Measured because I thought it was interesting, it's not factored into any of the equations)

Open Grown
Ht: 95.6' (Nikon 440/clinometer)
CBH: 116"
Avg Spread: 54' (AF Method)
Ht to First Branch: 9' (Measured because I thought it was interesting, it's not factored into any of the equations)

The following Excel spreadsheet shows four methods: AF, Adj AF (crown not divided by 4), TDI, and Adj TDI (Max Girth Squared instead of Max Girth). A few observations:

- All four methods score the forest grown tree the highest, and I included some hypotheticals showing what happens if the girth of the open grown tree is increased.

- If the open grown tree's girth was 5 inches bigger, the Adj AF (crown not divided by 4) method produces a bigger number for the open grown tree.

- If the open grown tree's girth was 17 inches bigger, the AF and TDI methods produce a bigger number for the open grown tree.

- If the open grown tree's girth was 36 inches bigger, the Adj TDI (Max Girth Squared instead of Max Girth) produces a bigger number for the open grown tree.

- Since these trees are so much smaller than what I used for the species maximums, it puts the bigger girthed tree at a disadvantage when using the Adj TDI (Max Girth Squared instead of Max Girth). This disadvantage should be reduced or eliminated for trees that are much closer to their species maximums.
AF-TDI Comparison - Matt - 2 Tuliptrees.PNG
AF-TDIComparison-Matt-2 Tuliptrees.xlsx
(17.98 KiB) Downloaded 14 times
The next two photos were both taken at a distance of 75' from the base, and at 4.5º above the base. A 4.5' stretch of tape is used for perspective.
Forest grown, 75' from base, 4.5 degrees above base
Forest grown, 75' from base, 4.5 degrees above base
Open Grown, 75' from base, 4.5 degrees above base
Open Grown, 75' from base, 4.5 degrees above base
Here's an assortment of other photos:
Forest grown
Forest grown
Forest grown
Forest grown
Forest grown
Forest grown
Forest grown
Forest grown
Open grown
Open grown
Open grown
Open grown
Open grown
Open grown
Matt

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