Tree Height Concepts

Tree Height Concepts

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TOPIC: New concept for measuring tree height
http://groups.google.com/group/entstrees/browse_thread/thread/d121b5363900f28e?hl=en
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== 1 of 6 ==
Date: Sat, Jun 14 2008 4:19 pm
From: dbhguru@comcast.net

ENTS,

What is our ENTS rule for measuring tree height? We find the highest twig. We locate, as close as we can, the mid-slope position of the base of the tree. We then measure the difference in elevation between the two points. Since the base of most trees follows an irregular path, we often locate the highest point that the tree touches earth, the lowest point, and take an average of the two. In this sense, the top point is a maximum and the low point is an average. Why don't we compute a maximum height for a tree as the height difference between the highest twig and the lowest spot on the trunk where the there is a vertical path from that point up the trunk as opposed to trunk/root flare? I'm just asking the question.
If we see reasons for calculating maximum limb length and/or maximum crown spread as well as the customary average crown spread, then maximum height we should be calculating maximum height in a way that doesn't include averaging.
For important trees, I think we likely agree that ENTS should take a number of measurements to describe a tree (as opposed to the standard three) to include:

1. GBH
2. Girth just above the root swell (GRH?).
3. Maximum height
4. Maximum limb length
5. Maximum crown spread
6. Average crown spread.

If we are a glutton for punishment, we may also add:

7. Trunk volume
8. Limb volume

But whether we take all or just some of the above, are we clear on the measurement protocals? For example, where do we establish the tree's base, i.e. upslope, mid-slope, or lowest point of vertical wood? Will Blozan and I are giving the question thought. Ed, I'm sure you will have insightful comments to offer, as will others of you. Of one thing I am sure, for ENTS purposes, if we suspect a measurement rule is influenced by economic considerations, we should move away from that rule. What we in ENTS seek is to capture the whole tree. We can always take conventional measurements to satisfy champion tree lists, but beyond that, where do we take the art of tree measuring?
We have discussed conventions on measuring single and multi-stem trees without a consensus. Maybe we can start simpler and agree on what constitutes maximum tree height.

Bob

== 2 of 6 ==
Date: Sat, Jun 14 2008 4:40 pm
From: DON BERTOLETTE

Bob-
What constitutes maximum tree height?
The maximum distance between two horizontal planes, the first of which barely touches the tallest twig/leaf/live plant part and the second which bisects the trees root collar. Maximum tree height is the least vertical distance between those two planes.
-Don

== 3 of 6 ==
Date: Sat, Jun 14 2008 5:14 pm
From: dbhguru@comcast.net

Don,

Yes, of course. Your definition is the one that we have followed and I have long applied. I'm asking if the lower limit must be the plane that bisects the root collar. If we can follow vertical wood to a low point, would that not be the equivalent of finding the tip of the highest twig? Just wondering.

== 4 of 6 ==
Date: Sat, Jun 14 2008 5:43 pm
From: DON BERTOLETTE

bob-
Well, to really measure the full extent, the lowest root hair tip would be definitive, but difficult to non-destructively measure...
The bottom measuring point is a bit messy...the root collar is not always apparent to the untrained eye. The standard ENTS/midslope/where the acorn was, is somewhat less subject to dispute...the average between highest and lowest ground levels might work...
-don

== 5 of 6 ==
Date: Sat, Jun 14 2008 5:59 pm
From: "Edward Frank"

Bob,

I will have more to say about this after some thought. I your list I would add crown thickens which would measure the height of the base of the crown as well as the base of the tree, and I would like to see some good way to estimate crown volume and density. Of the calculations you list - I really see no purpose in measuring maximum limb length nor maximum crown spread as these values do not seem to have any real meaning. They are something that can be measured, but why bother when they are do not tell you anything? They are just numbers for the sake of measuring numbers.

The midslope of the base of the trunk seems reasonable place to measure height, because that requires a minimum amount of interpretation of where the root ends and the trunk begins, thus it is a repeatable value and also it best fits with the basic where the seed sprouted concept. It may fall short in cases where the trees are growing on a nurse log or stump, but can still be applied. Arguments can be made that the best point to measure is on the high side of the slope, because this eliminates the problem of the midpoint being below high side ground level when dealing with steep slopes or really fat trees. -- this goes along with the idea that the basic girth should be measured with respect to the same point as the tree height --. It can be argued that the full height of the trunk should be measured starting from where the base of trunk extends farther downward on the low side of the slope. This is also a reasonable argument. Any of these could be used we just need to be consistent and choose one protocol to use to determine the base point for height.

Ed Frank

== 6 of 6 ==
Date: Sat, Jun 14 2008 7:04 pm
From: "Steve Galehouse"

This is an interesting discussion, which to me means tree height vs. tree
length( a tree leaning over a slope may not have great height, but could
well have a length longer than its height). To me it seems the length of a
tree is as valid a measure as the height.

Steve

== 2 of 6 ==
Date: Sat, Jun 14 2008 9:02 pm
From: DON BERTOLETTE

Ed/Steve-
While everyone is dancing around length as a measure, presumably to avoid the commercial aspect (logging), but any modeling would need the length. It's easy to image a leaner, or sweeper, but my own image hangs over a river and has a rope hanging from it...:>) Ed's right though, anytime a trunk leans so much that it's significantly longer than it is tall, it's likely to be fairly soon that it falls.
-DonRB

== 3 of 6 ==
Date: Sat, Jun 14 2008 10:24 pm
From: "Edward Frank"

Don,

I visualize the trees as physical objects to be measured. I am not tip-toeing around the commercial logging measures because I know little of them and do not think in terms of logging measures. I general what little I do know of these measures are not adequate for what I am envisioning, and I really am not interested in the commercial aspects of tree measurement. I am not denigrating foresters and their skill sets. Foresters provide a valuable service and have developed techniques designed for their needs. However, it is not the perspective from which I am thinking,nor the perspective from which I view an individual tree or forest, nor is it something I wish to implement. I am not avoiding those commercial aspects of tree measurement, I just don't think about them. They are a non-factor that is neither being avoided nor embraced. Indifference, rather than avoidance, so your base assumption is in error.

Ed

== 4 of 6 ==
Date: Sat, Jun 14 2008 10:38 pm
From: "Edward Frank"

Don, ENTS,

I should add that if I felt a measurement technique was of value, I would adopt it, or encourage its adoption, regardless of the source, whether it be from commercial forestry or tiddley-winks. So if you have some forestry based measurements you find useful for individual trees, or stand based measurements that you think ENTS should adopt, please expound upon them. Useful techniques and measurements are what I am interested in pursuing. The commercial aspects, not so much.

Ed

== 5 of 6 ==
Date: Sat, Jun 14 2008 11:10 pm
From: DON BERTOLETTE

Ed-
I wasn't referring to you in my what now appears to be a rather oblique statement.

Forestry has little to add to accurate height measurement, but is rather good at measuring in increments of 4, 8, 16 foot lengths. The level of accuracy is usually in increments of sawblade widths (aka saw kerf). But totally commercial.
But here's a question to ponder...for trees with significant sweep or crook (essentially the pith describes an arc rather than a straight line), how would you accurately measure their length? There are essentially three uneven length arcs in lateral cross-section, the pith describing the middle arc.
-DonRB

== 6 of 6 ==
Date: Sat, Jun 14 2008 11:44 pm
From: "Edward Frank"

Don,

If you accept the premise that the height of the tree is the vertical distance between the top most twig and the base of the tree,where the base point is defined as the point at which the seed sprouted, then it would follow that the length of a tree would be the length of the tree measured along the central pith of the trunk, or the length of the limb as measured along the pith of the limb. I would say the start position for the limb would ideally be the base of the limb where it first sprouted from the side of the trunk, but as that may now be buried somewhere in the trunk mass, and as projecting the starting point of the limb to the central pith of the trunk would add length of the radius of the trunk to the limb length, the best compromise would be that the base of the limb for limb length would be from the surface point the limb branched from the trunk, or other limb.

Ed Frank

== 2 of 11 ==
Date: Sun, Jun 15 2008 6:06 am
From: "Will Blozan"

Ed, Steve, ENTS

Trunk length- straight and curved- is absolutely needed for trunk
wood/volume measurements. Some of the Tsuga Search hemlocks had nearly 700
FEET of trunk wood measured in the course of volume modeling- and this
figure is low due to the rather coarse resolution we used. The current Usis
Hemlock Mapping Project will likely result in well over 1,000 feet of trunks
measured- in a single tree.

Obviously, the complexity of these ancient hemlocks cannot be captured by
height or volume alone. This is a great discussion and each persons answer
will be determined by the use of the information and the goals for going to
the tree in the first place.

"Reiteration fountain", Cheoah Hemlock 3-31-2006

Will

== 3 of 11 ==
Date: Sun, Jun 15 2008 6:24 am
From: "Will Blozan"

Steve,

Seems to me a tree would be longer than it is tall only if it's lean was
less than 45 degrees and it conformed to an idealized shape; straight, no
errant vertical branches, etc. Sometimes the tip will be lower that the root
collar. Can trees have negative height?

Will

== 4 of 11 ==
Date: Sun, Jun 15 2008 2:50 pm
From: dbhguru@comcast.net

Will,

Excellent answer. If we are trying to capture the massiveness and complexity of a large tree, be it a conifer or non-conifer, then the set of common champion tree measurements will always fall short of doing the job. I doubt that any of us on this list would disagree with that statement. However, as you point out, even throwing in volume calculations doesn't finish the job. We obviously have a ways to go on trees such as Usis and the huge contorted live oaks that Larry finds. Such complex forms as these giants illustrate our current measuring shortfalls and our numerous discussions on what to measure and the protocols to follow reveal the distance we have yet to go. So the searching must continue.

ENTS,

In terms of the measurements we are currently taking, I agree with Will. Our choices should acknowledge the use to which the information is intended. We need to put more thought into the concept of measuring tailored to clearly defined purposes. For instance, there is a pin oak in Childs Memorial Park, Northampton that has constricted crown growth due to the proximity of nearby trees. A lower average crown spread results for the pin oak as a predictable result of its restricted growing space. However, from one vantage point, the crown spread of the oak is quite impressive and greatly enhances the visual impact of the tree. The wide spread in the particular direction combined with the oak's overall pleasing symmetry maximizes the tree's aesthetic impact for attuned viewes. As a consequence, the maximum crown spread as seen from the location becomes relevant to convey the oak's aesthetic appeal as opposed to ecological role. Maximum crown spread may be relevant for aesthetics sh
ould we seek to quantify that value system as Ed has suggested we do in the past. Quantifying individual tree aesthetics is outside the box for most of us, but we shouldn't shut the door to thinking about it as a subject.

In my lead-off email to this thread, I suggested that we might want to consider alternative definitions for maximum height. I didn't intend to suggest that we should necessarily abandon older standards. There are reasons to have them, one of which is for comparison purposes to what we, ourselves, as well as others have obtained for many, many trees. However, we shouldn't be constrained by what others use as a definition for maximum height. But regardless, we always need to be discussing our measuring techniques, definitions, and priorities. This isn't engaging in repetition for the sake of chatting and perpetuating ENTS camaraderie. The biggest benefit that flows from continued tree measuring discussions is the gradual expansion of the ENTS collective tree consciousness, a consciousness that eventually takes on many forms from the purely physical, to the aesthetic, to the metaphysical, with the latter important for the measuring.

I hope we will agree to continue this discussion thread and explore the multiple purposes to be served by our measuring mission as we speak for the trees. In expanding our tree consciousness, we should resolve never to constrain our thinking just to be compatible with existing systems. As that resolve translates to tree measuring, we can always take the measurements needed to have comparable data to other systems, but we in ENTS should be heading in new directions.

I often think of the number of trees that Will Blozan has climbed and modeled, yet he is constantly encountering surprises that cannot be seen from the ground. His perception and understanding of the tree as an amazingly adaptive organism, serving many ecological purposes, is alway expanding.

Bob

== 5 of 11 ==
Date: Sun, Jun 15 2008 3:32 pm
From: DON BERTOLETTE

Bob-
I would think, along with Ed, that the crown dimension along with total tree height would be a valuable figure...and it just takes one quick clinometer reading in most cases. That would be height of crown base (you're already getting spread and height of crown top). Although my previous use would not be directed valued by ENTS (to model fire spread through a forest, it's necessary to know what it's burning through, ie, we could factor crown biomass from typical species volumes, and forest species composition), but part of what makes a tree magnificent is it's crown, and a measure of it's dimension is reasonably obtained, objectively measured, and useful for many other ecological concerns (bottom of crown may be due to herbivory, ground fires, crown closure, etc.).
-Don

== 6 of 11 ==
Date: Sun, Jun 15 2008 3:53 pm
From: DON BERTOLETTE

Will/Steve-
Any arc will be 'longer' than the straight line chord that would connect each end.
-DonRB

== 8 of 11 ==
Date: Sun, Jun 15 2008 4:51 pm
From: dbhguru@comcast.net

Don,

Yes, I readily agree that measures of crown dimension are valuable for ecological, aesthetic, and other reasons (fire management). With my TruPulse 360, I now have many measurement possibilities open to me, although I have explored next to none. I plan to get to them as dendromorphometry takes shape beyond my talking about it.

Bob

== 11 of 11 ==
Date: Sun, Jun 15 2008 7:20 pm
From: DON BERTOLETTE

Ed-
For a variety of reasons (soil creep, overhanging older crowns, etc.) a young tree may start out growing off of vertical. If the perturbing force stabilizes, most trees will eventually seek a vertical growth habit. For those of us faced with evaluating hazard trees, we see that as a sign of self-correction, good health, and we'll extend the monitoring duration for later returns.

But that gradual change from off vertical to vertical is called sweep, and while usually not perfectly mathematically like an arc (at least not for long), I suspect Bob has some forms in mind that could mathematically describe 'sweep' in a tree. The fact that the tree is bigger at the bottom and thins as it goes up is an added complexityto model, but not insurmountable.
-DonRB

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