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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Eastern Native Tree Society http://www.nativetreesociety.org
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