Single-stem or Multi-stem?

Native Tree Society Tree Measuring Guidelines and related materials.

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#11)  Re: Single-stem or Multi-stem?

Postby morgan » Wed Sep 25, 2013 9:26 pm

What is pith? What's a pith test?

To give you an idea of the size of this tree, the bench is 6 feet long, my wife is 5 feet 7, and I measured the girth as ~24 feet. It's also really, really tall.

Does two trunks fused together mean 2 genetically different trees? Or 2 trunks from the same sapling and same seed that forked early in life.
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#12)  Re: Single-stem or Multi-stem?

Postby morgan » Wed Sep 25, 2013 9:42 pm

As for my answer to Don's question, I'm sure a DNA study on the "tree" in his pic would show it's two genetically different trees. It's ridiculous that anybody considered that to be one tree. As for my tree, the two fused trunks both produce leaves that are consistant with london plane, the hybrid, which means they are midway between the shape of an american sycamore, which is maple shaped, and plane which has much longer fingers on the "hand" of the leaf.

I think this tree grew from one seed, forked when it was 3 feet tall, and grew. The two stems pushed each other apart as they grew. That's my opinion.
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#13)  Re: Single-stem or Multi-stem?

Postby edfrank » Wed Sep 25, 2013 11:51 pm

Morgan,

The pith test basically is where you draw a line down the center of the trunk - the pith - and see where it intersects.  If it intersects the ground before merging with a second trunk it definitely is a multitrunk tree.  If it intersects the second trunk well above ground level then it likely would be a low branch.  If it intersects teh second trunk at just above ground level, then in most cases it likely was two trunks originally that formed close together and pushed against each other as they grew fatter distorting the apparent position of the pith.  For champion trees there should be separate lists for mutlitrunk trees and single trunk trees as they are different growth forms.   I believe if there is only to be one list, then only single trunk trees should be considered.   If the trunks are genetically different, then they clearly are separate trees that have grown together.  If they grew as different sprouts from a single root mass, usually after the original tree was downed, then they would be genetically the same.  You can argue that this is a single tree, or you can argue that these are separate trees each sharing some portion of a combined root mass, but essentially acting otherwise as individuals, or you can argue they are something between these alternatives.  But basically for champion tree purposes multitrunk trees and single trunk trees are different growth forms, even if all of the trunks are genetically the same, and should not be considered as champions on the same listing as single trunk trees.  I favor separate listings for both forms, but if there is to be only one list of champions it should include only those exhibiting a single trunk growth form, or one in which only the measurements of a single trunk of a multitrunk form is considered.

Edward Forrest Frank
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#14)  Re: Single-stem or Multi-stem?

Postby tsharp » Thu Sep 26, 2013 4:38 am

Don: You picked a good example to "blur the line" between single stem vrs. multi-stem trees. I will give it a shot even though I have very limited experience with Live Oaks. The way I interpret the picture using the "Pith Test" it appears the piths would join at knee or calf level and thus should be measured as a single  stem tree with the circumference measured at its smallest dimension at that height or lower. I hope "Live Oak Larry" will weigh in with his opinion.
Good example where the person on the ground has to make their best judgement.
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#15)  Re: Single-stem or Multi-stem?

Postby edfrank » Thu Sep 26, 2013 7:06 am

Don,

With regard to the Texas Live oak, I would call this a double trunk.  Only by doing some severe mental contortions can you justify calling this being a single trunk tree by calling it a very low branching or a resprout from a partially fallen trunk.  The basal area is fused but I don't see how you can realistically call that the equivalent of a "single trunk."  If the pith traces would merge just above the ground, unless they are at some abrupt angle like the octopus spruce, then I think the best interpretation is that they are two separate trunks that grew relatively close together.  The apparent merger of the separate piths isn't the result of low branching but one of the two closely space stems pushing against each other once they reached some nominal size.  The result is that in these low apparently merging piths is that the pith is offset from the center of the trunk and curves downward as separate entities rather than merging low to the ground.  Could this interpretation be wrong?  Yes, but it is in my opinion the best and most likely interpretation of what is shown in the photograph.  

Remember also that I am not in favor of being falsely conservative with the interpretations.  Some would call any tree in which there is a question of the whether it is a double or not a multitrunk tree "just to be safe" while I would favor using the best interpretation as to whether or not it was a single trunk or a double trunk.  

If I would have believed this to have been a single trunk rather than a double, then the girth should be measured at the narrowest point below 4.5 feet and that height noted in the girth description.  

But to my mind there is virtually no doubt that this is a double tree.  We should not be bending over backwards to find a way to see these examples as somehow being single trunks, but should be making the best guess or best interpretation as to whether they are single or double trunks.  It seems in many of these cases the way many of us are going has the exact same flaw in the opposite direction as does those who want to call any example for which there is any doubt a double.  Only in this case people want to call anything in which there is even the slightest possibility that this might be a single trunk to be a single trunk.  No.  Use the best and most likely interpretation and let the wood chips fall where they may.  Don't be overly accommodating and do mental gymnastics to call these things singles, and don't call everything where there is the slightest a doubt a double or multitrunk.

Edward Forrest Frank
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#16)  Re: Single-stem or Multi-stem?

Postby Joe » Thu Sep 26, 2013 7:57 am

I'm still waiting for someone to explain why it's so important to get good measurements- until that theme is resolved, much of the discussion reminds me of the Medieval debate over how many angels can dance on a pin. The development of that theme is as important or more important as the development of measuring techniques.
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#17)  Re: Single-stem or Multi-stem?

Postby Bart Bouricius » Thu Sep 26, 2013 8:44 am

Joe,

Because it's there?  The reason it is important to get good measurements is that most of the people in the organizations discussing this are fanatical about the subject and that is sufficient.  They just don't like being sloppy, and think if you are going to do something at all, then do it right.  There are also scientific reasons to get good measurements when studying tree growth patterns etc., but let me ask you a question.  Why is it important to appreciate the beauty of trees?

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#18)  Re: Single-stem or Multi-stem?

Postby Joe » Thu Sep 26, 2013 10:39 am

Bart Bouricius wrote:Joe,

Because it's there?  The reason it is important to get good measurements is that most of the people in the organizations discussing this are fanatical about the subject and that is sufficient.  They just don't like being sloppy, and think if you are going to do something at all, then do it right.  There are also scientific reasons to get good measurements when studying tree growth patterns etc., but let me ask you a question.  Why is it important to appreciate the beauty of trees?


our awareness of aesthetic values is one of the things that seperates us from our ape relatives

but for that alone, we don't need super accurate measurements- only good science regarding trees/forests will help us solve the many policy issues about forests

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#19)  Re: Single-stem or Multi-stem?

Postby morgan » Thu Sep 26, 2013 10:48 am

On my sycamore/plane the two piths intersect below ground level. What's that mean?
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#20)  Re: Single-stem or Multi-stem?

Postby edfrank » Thu Sep 26, 2013 11:07 am

It means they are two separate trunks and should be ineligible as a champion tree on a list of single trunk champions, but would be considered for a list of multitrunk champions.  They likely grew from the same root clump and so would be genetically the same.
"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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