For those on the list who shy away from our
discussions of tree
mathematics, you might not want to read this post - then again,
might, at least for information purposes - especially the
the list. Will Blozan, Jess Riddle, John Eichholz, and myself
finally decided (more or less) to embark upon the perilous
writing a guide book to simple and intermediate tree mathematcis.
sure Ed Frank will be involved. Such an ENTS undertaking without
participation is unthinkable. I expect a few others to sign on.
We will probably title the book something like
-the Science of Measuring Trees". Hopefully, some of the
big guns on
ENTS will join us, or at least review the work as it proceeds.
guns of whom I speak are the stellar PhD scientists on the list,
Drs. Bob Van Pelt, Lee Frelick, Don Bragg, Tom Diggins, Larry
Dave Orwig, John Okeefe, Roman Dial, etc. There are other
guns, but we don't often hear from them. So I'm including only
post and/or who I know.
There are many topics that need to be included
in the planned book.
Obviously, the ENTS-engineered methods for measuring tree
spread, and trunk volumes would be included. A full discussion
common tree-measuring techniques would also be included with
cons provided for each method. We would discuss which shortcuts
which ones don't. An appendix would provide a review of the
trigonometry that we commonly use to include derivations of some
formulas that we use. We would provide a review of the accuracy
instruments that we use and how to get the most out of each
would be lots of pictures and diagrams.
Folks, this is a work that needs to be
done. There is so much stuff
out there in the way of measuring and calculating techniques
hidden, simplifying assumptions about trees that are just not
much of the time. For example, I was looking at the internet,
for cross-sectional area determinations and found the following.
the referenced table.
Cross-sectional Areas of Trees
Dr. Kim D. Coder
The University of Georgia
Many tree appraisal, measurement, and structural mechanics
require cross-sectional areas at some given height or point
along a stem
or branch for completing calculations. Table 1 presents these
cross-sectional areas in square feet and square inches across
diameters from 1 to 75.
Values were determined by:
Cross-sectional area (square inches) = 0.785 × DIAMETER^2
Cross-sectional area (square feet) = (0.785 × DIAMETER^2) / 144
who live and breath tree dimensions and formulas, will quickly
recognize that the 0.785 factor comes from the area of a circle
A = PI * D^2/4 where PI
= 3.141593 and PI/4 = 0.785.
So what's my point? The assumption being made
is that the
cross-sectional area of the trunk at the point of interest is
that of a
circle. So, all that the user of this method gains is the
3.141593/4 being reduced to the constant 0.785. The table that
accompanies the formula gives the cross-sectional area for
1 to 125 inches.
This simplified formula and accompanying table
is an example of one
of the shortcuts I alluded to, but in the age of electronic
and computers, it is hardly needed. What IS needed is a better
determine the cross-sectional area of a tree when it isn't
almost circular. Making the assumption of circularity is
all do, but there are times when we clearly shouldn't. And our
distinguished president of ENTS, Will Blozan, has risen
meet that challenge. Will and associates have engineered a
where they climb the tree to the offending trunk section. These
trunk sections, often where fused trunks part company, simply
act like a self-respecting cylinders and challengingly stick
tongues out at Will. Honest, folks, I've seen it happen. Will
encloses the trunk with sticks that form an enclosing a
He then measures distances from the rectangular frame to the
then enter his offsets into an Excel spreadsheet and use a
trapezoids to calculate the blank space. We arrive at a pretty
cross-sectional area of the trunk at that point.
Now who, but thoroughly obsessed Ents, would
go to so much trouble to
measure the cross-sectional area of a tree trunk? But, alas, we
help ourselves. We must do it. It is our calling. So, we'll
obsession by writing a book.
Robert T. Leverett
Cofounder, Eastern Native Tree Society