For our new members, we should
explain what all the fuss is about over tree measuring and
associated errors. So at the risk of redundancy in the extreme,
for our new members, what follows is some ENTS history.
15 years ago, I set out to document the old growth forests that
I was exploring in the Berkshires and Taconics of western
Massachusetts. I wanted to record the dimensions of significant
trees I was encountering as part of the documentation. I
borrowed a Haga altimeter (a brand of clinometer) from Harvard
Forest and proceeded to measure lots of trees and convey the
results to organizations and people who were interested in old
growth. Along the way I met a timber framer-architect-surveyor
named Jack Sobon. My tree heights were often higher than his and
the numbers for one particular tree, a sugar maple at the base
of Todd Mtn, that I had measured sounded impossible to him. So
we measured the tree with his transit and my clinometer-based
measurement proved to be 21 feet off. That opened my eyes,
especially considering that on different occasions, a dozen or
so other folks had measured the tree with me and those folks
were not amateurs. They were foresters, plant ecologists, forest
ecologists, naturalists, etc.
sat down and began analyzing the possible sources of error that
led to the sizable error. With mathematics as my minor in
college, I wasn't timid about tackling the problem. I began by
considering the actual shapes of trees and where their high
points might be. I examined lots of trees and drew lots of
diagrams and quickly came to realize that the fatal assumption
that I had made as well as the others was that the spot in the
crown I was measuring as the top, that from a distance looked
like it was over the base, was in fact often 5 to 10 feet, and
occasionally much more, horizontally out from the base. But
traditional calculations treated as though you were always
measuring a point over the base. That realization and
discussions with Will Blozan spawned our methods of crown
cross-triangulation. The adjustment helped us greatly. The
method is described in a book Will, Jack, and I wrote entitled:
"Stalking the Forest Monarchs - A Guide to Measuring
Champion Trees". We covered use of the laser and included
advanced methods for measuring average crown spread. We extended
our reach through e-mail and the internet to include numerous
diagrams and explanations that both Will Blozan and I would
convert American Forests and the coordinators of the state-level
champion tree programs. Will Blozan and I knew long ago that we
had an unusual situation to deal with. For lack of a laser
device that could measure distance to an actual point in the
crown, methods had been adopted that worked only for idealized
trees- the vertical telephone pole in the level parking lot
analogy and the proponents of the tangent-based methods were not
inclined to give ground. They just couldn't accept that they
were using flawed techniques. American Forests was a
particularly tough nut to crack. I've since given up on them.
making our greatest inroads with the state coordinators, which
Georgia coordinator Will Fell suggested about 2 years ago.
Perhaps the biggest boost came for us was when Dr. Lee Frelich
joined ENTS and began helping us promot and refine the ENTS
methods. Others in academic circles who had previously balked at
coming on board with us listened to Lee. Dr. Tom Diggins has
added more academic horsepower.
Lee and Tom came on board, a second big boost has come as we
began picking up mathematicians like John Eichholz and Howard
Stoner. Ed Frank must now be counted in among the heavy weights.
With experienced foresters like Don Bertolette, Russ Richardson,
Will Fell, and others on board, the circle is being closed.
we making a big to do over nothing? Only if accuracy is
unimportant and that would be a hard sell for anybody who is
scientifically inclined. To suggest that we should be sure to
measure circumference (and compute diamter) to the nearest tenth
of an inch, at a prescribed distance above the base, but now
worry if we're off by tens of feet in another measurement would
be bizarre to say the least. And we do not exaggerate when we
point out measurements that have been in error by tens of feet.
many past occasions, either Colby Rucker, Will Blozan, myself,
Dale Luthringer, or others pointed to tree height errors made by
measurers using the % slope method that were between 20 and a
whopping 60 or more feet. There is no way that errors of such
magnitude can be acceptable to a serious endeavor and there in
lies the answer. Tree measuring for the champion lists wasn't
really a serious endeavor for those in professions that
routinely dealt with tree measurements for economic purposes.
And there was no compelling reason why they should have felt
differently. However, the same is not true for ENTS.
of our primary purposes is to profile the growth capabilities
and attendant limits of eastern tree species across their
natural ranges. That requires we take accuracy in our
measurements seriously. Measurements for big tree contests are
peripheral to our interests, though we do not shy away from the
fun of hunting record trees. But we have no compelling interest
in pushing the champion tree point system. Individual
measurements of circumference, height, and spread, trunk and
limb volume, percent of crown, crown area, point of major
branching, rate of taper, etc. all these are of interest to us.