Beth,
The proposed ENTS point formula admittedly works best for trees with long
straight trunks that can be modeled with a regular geometrical form,
principally a neiloid, cone, or paraboloid. I chose the cone for illustration
purposes, but either of the other two forms would have worked just as well.
The question of what kind of formula works for a big spreader like the
live oaks that Larry measures is probably not going to be adequately determined
for a long time. There is just too much wood tied up in the complex network of
limbs. The ENTSPTS formula is not the answer for trees of that shape, but then
neither is the champion tree formula. Consider the table below.
HGT CIR SPD CHP PTS ENTSPTS
50 12 12022472
6524120383374.4
13024120448748.8
For trees with spreads of 120 feet, we know there is lots of wood
committed to the limbs. Looking at the entries in the table, it is apparent
that ENTSPTS does not capture limb wood. The champion tree formula actually
does better, but going from rows 2 to 3 is just not logical for the champion
tree formula. A 130-foot tall tree with a 120-foot crownspread implies a lot
more wood than the spread of points of 383 to 448 indicates.
The problem we're experiencing in calculating an absolute number of
points for a tree stems from the one size fits all approach. I understand that
it was for simplicity's sake and to try to get the general public involved, but
the formula doesn't work well enough for a group like ENTS.
For a system of relative comparisons, TDI works well and we may never get
beyond that, i.e. relative comparisons. However, for white pines in New
England, I need more of an absolute measure. The amount of limb mass for a
tall, straight conifer may not be more than 5% or 6% of trunk volume. So, I
don't have to worry too much about the limbs and can apply the proposed
formula. By contrast, the limb volume versus trunk volume ratio may approach
50% for live oaks. I wouldn't apply to formula to trees of those shapes. So,
the search must go on.
I apologize to the list for not making it clear that I had conifers in
mind for the proposed formula. Very clumsy of me.
Sorry you won't be able to make it to the rendezvous. The one in 2009
will be in Cook Forest. That is considerably closer to help for time and
expense travel.
Bob
-------------- Original message --------------
From: Beth Koebel <[EMAIL PROTECTED]>
Bob,
Not being a math major (I had to drop CAL I because I couldn't understand it),
it looks like you are using a cone to measure the volume as the "gold standard"
and then using the new ENTPTS2 to get the measurements that are often taken,
height and circumfence, to match it. If this is the case, then would this work
also for trees like palms or any other tree in which there is a trunk without
branches for say 50 or so feet then a relatively flat crown(umbrella shaped)?
How about the classic hardwood shaped tree (golf ball on a tee)?
BTW, I am not going to be able to make it to the ENTS gathering in Oct. as it
is too close to my projected closing. Sorry, I wish I could've made it. Maybe
the next one.
Beth
"Information is moving--you know, nightly news is one way, of course, but it's
also moving through the blogosphere and through the Internets."
Washington DC, May 2, 2007 George W. Bush
--- On Wed, 9/24/08, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
From: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Subject: [ENTS] Sneak preview
To: [email protected]
Date: Wednesday, September 24, 2008, 9:25 AM
ENTS,
Folks, it is time to reconsider our two ENTS methods of ranking the size of
trees: ENTSPTS and TDI. The TDI system is sound. No modifications needed there,
but ENTSPTS is ailing, the reason being that the number of points awarded does
not track well enough with increases in trunk volume . The following table
compares the effect of tree size increases using the old way of calculating
ENTSPTS ( height x circumference) , a proposed new way of calculating ENTSPTS (
[height x Circumference ^2]/100), and an abbreviated version of the champion
tree formula ( 12 x circumference + height).
Height Circ VOL-CONEratio ENTSPTS ratio ENTSPTS2 ratio Champ
Tree Pts ratio
50884.8 400 32 146
5012190.8 2.3600 1.572 2.3194 1.3
5016339.2 4.0800 2.0128 4.0242 1.7
1008169.6 2.0800 2.064 2.0196 1.3
10012381.6 4.51200 3.0144 4.5244 1.7
10016678.4 8.01600 4.0256 8.0292 2.0
1508254.4 3.01200 3.096 3.0246 1.7
15012572.4 6.81800 4.5216 6.8294 2.0
150161017.6 12.02400 6.0384 12.0342 2.3
Looking at the table, we see that the ratio of the volume of the largest
tree to the volume of the smallest is 12 to 1. The ratio of ENTSPTS of the
largest tree to the smallest is 6 to 1. The ratio of modified ENTSPTS of the
largest to the smallest tree is 12 to 1 (just what we want), and the ratio of
modified champion tree points of the largest to smallest tree is 2.3 to 1. The
change in modified ENTSPTS tracks perfectly with conical volume. Each ratio in
the above table is the current entry divided by the first entry in the
respective column, not the preceding entry in the column. The purpose of the
ratio columns is to show how points track with changes in volume as measured by
a form such as the cone or paraboloid.
The reason I chose a scaling factor of 100 for modified ENTSPTS is to
bring the point total more in line with numbers that come from the champion
tree formula. Additionally, it is computationally simple. I leave out
hypothetical crown spread in the table. However, were we to include realistic
crownspreads for the size trees indicated by height and circumference, the
ratio of the points of the largest tree to the smallest would increase slightly
- perhaps 2.5 to 1.
I've discussed the new system of ENTSPTS with Ed off list. Ed is solidly
behind it. Ed also mentioned that John Eichholz had once before pointed out the
value of C^2 versus C as the factor dealing with circumference. I mentioned the
proposed new method briefly to Will in a recent phone conversation and told him
I'd shortly present some analysis. The above table is the first step in that
direction.
Thoughts anyone?
Bob
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