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TOPIC: Back to tree modeling
http://groups.google.com/group/entstrees/browse_thread/thread/fc988a81feef3be8?hl=en
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== 1 of 1 ==
Date: Tues, Aug 19 2008 9:27 pm
From: "Edward Forrest Frank"
Bob,
Nice to see you back at tree modeling and preparing to scare people
off the list with mathematics.
I have mentioned this before but I want to suggest cylinder
occupation again in this context. In the study of the volumes of
hemlocks in the Tsuga Search Project a ration could be determined
between the actual volume of the tree and the volume of a cylinder
of the same height as the tree and of the same diameter as the tree
at breast height. What was found was that at the lower end of the
scale were outlier percentages representing trees with an abnormally
fat base. The unusually large base diameter would yield a lower than
average % cylinder occupation. Above this was the normal range of
trees with a normal girth to height ratio and generally uniform
tapers. Those at the lower end of the spectrum are tree which taper
rapidly, while at the upper end of the normal spectrum are those
trees that have a slower taper for a much greater portion of the
trees height before tapering to a point. The third group of trees
were those that had their tops damaged or removed. Since these trees
had the profile in their lower portion more representative of larger
and taller trees, and a foreshortened top segment representing the
least cylinder occupation of any portion of the tree, these tree had
an anomalously high % cylinder occupation.
The same could be done for the pine volumes you are measuring. I
would expect, if this tree you measured in Bryant Woods has had its
top removed and regrown that it would be in the anomalously high
outlier or at least in the upper end of the normal spectrum.
What can this tell you? By itself it can indicate that a particular
tree has been damaged in the past. it is a measure nor of size of
the tree but of shape. I am wondering if there would be a general
trend in this value from younger to older trees in an area
indicating that the trees basic shape changes with time and as it
grows? I am also wondering wonder if there might be a regional trend
from south to north that could be determined? The other thing is
would there be a clustering of values from trees in a particular
environment? For example, would the trees nearer the coast that
Andrew Joslin thinks are kept short because of winds, form a
meaningful cluster of data points?
This goes along with the idea of plotting three parameters on a
triangular ternary plot. Initially I was thinking about plotting
girth - height - and average crown spread. This would be a shape
diagram for different species of trees, perhaps also show a
distinction between young and old trees in a species, and perhaps
variations in shape with location or environment. Perhaps the plot
of height - girth - and volume would also be interesting. I have a
basic ternary plot program posted in the measurement section of the
website. Does anyone know or have a macro to create ternary plots in
excel?
I certainly think this is something worth pursuing, and you may have
enough volume measurements at this point to do some preliminary
calculations and plots.
Ed Frank
== 2 of 6 ==
Date: Wed, Aug 20 2008 8:07 am
From: dbhguru@comcast.net
Ed,
Yea, I'm loading up for bear. A set of volume formulas is tumbling
around in my noodle getting ready to spill out and find their way
into e-mails. I hope that none of the 231 ENTS members will be
driven way, but remind the intimidated, that's what the e-mail
delete button is for.
You make a compelling case for calculating the percentage of a
cylinder occupied by a trunk. Each time you present your ideas on
the subject, they become more appealing. Let's call it the Frank
Volume Index (FVI). I particularly like the way it would help to
capture the volume for of "decapitated" pines that have
recovered enough to present us with very bushy, indistinct tops.
Good stuff.
Bob
== 3 of 6 ==
Date: Wed, Aug 20 2008 8:43 am
From: "Edward Forrest Frank"
Bob,
The concept should be called PCO or %CO for percent cylinder
occupation. I am all for descriptive names rather than names that
make people puzzle over what they mean.
Ed
== 4 of 6 ==
Date: Wed, Aug 20 2008 8:55 am
From: "Edward Forrest Frank"
Bob, ENTS,
The Percent Cylinder Occupation concept may not prove to be that
useful after we look at the numbers being generated. But the thing
is, at this point, it is a fairly simple number to calculate once
you have the tree volumes, so why not add a column to the
spreadsheet as see what the numbers reveal?
Ed
== 5 of 6 ==
Date: Wed, Aug 20 2008 10:50 am
From: DON BERTOLETTE
Bob/Ed-
A few nearly random thoughts...I was thinking that the index you are
labeling FVI, should stand for Forrest Volume Index, still giving Ed
appropriate credit...and yes, I too have in the past recommended
such a factor...it seems to me that statistically the population of
each species' old-growth form is not quite normal, but more
reflective of the increased likelihood of the environmental/climatic
variables over increased periods of time.
-DonRB
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