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TOPIC: Pin oak tells the story
http://groups.google.com/group/entstrees/browse_thread/thread/04848db8a70f2034?hl=en
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== 2 of 4 ==
Date: Tues, Jun 10 2008 12:00 am
From: DON BERTOLETTE
Bob-
Much of my time measuring trees in the woods was a function of my
various employers, and until the late 1980s, in the western US where
coniferous species are commercially dominant. In the year in year
out life of a forester, much of the measuring of trees that is done,
is done to predict volume for timber sales, so as to advertise it
with an idea of the value of what was to be offered up for contract
bidding. We got good at estimating volume and grade for fairly large
stands. Commercial valuation didn't include tree height, but height
to a predetermined commercial diameter limit (usually 4 to 6
inches). In our prime, I'd put us against your digital devices and
win a bunch of beers estimating height at which 4 or 6 inches
diameter was reached. Our work was randomly checked, and a lot of
integrity was tied up in how accurate we were.
In my third year as a forest tech, still in school at Humboldt, I
was crew chief on a Continuous Forest Inventory crew, on the
Shasta-Trinity National Forest in Northwestern California. Our
stands were overwhelmingly evergreen/coniferous, and simple to
measure. We visited probably 75 plots over the summer we had in
between classes, and carefully measured height, diameter at breast
height, species, grade, community/habitat type, etc. We measured
tree heights, from a two foot stump height which many times would be
outside the 'butt swell'. Height was measured according to the
tangent rule, although we didn't refer to it that way. Most of us
operated by rules of the thumb. Rule 1, horizontal distance needed
to exceed vertical distance. Rule 2, determine direction of lean
(sweep) and measure at right angles to it. Rule 3, once Rule 1 was
achieved, walk to a distance easy to convert in your head (200, 150
feet, 125 feet, 133 feet (or 132, if using topo clinometer)., Rule
4, measure top and bottom from same location. Acute angles were
better than obtuse (topographically, measure from as much above as
possible, as some coniferous species had rounded top that could
cause error from not seeing actual top).
When possible, for efficiency, we'd often walk out equidistant from
two or more trees if conditions permitted, which would allow us to
measure two or more trees from same location. Not often, but not
infrequently either, a series of trees would describe a rough line,
or better, an arc that permitted 'two birds with one stone'
opportunities.
When I went back East as a forest tech to Kentucky's Daniel Boone
National Forest, it was more of the same, but deciduous trees posed
special problems, as you well know. Even so, we had no real occasion
on year in year out basis for measuring total tree height to the
level of accuracy that ENTS achieves. We still measured to height of
commercial top (when the final info you need is number of 4/8/16
foot logs, there are very distinct points of diminishing returns in
careful measurement of top twigs). One tree in a hundred (not
actually, but indeed a small fraction) where measured accurately to
"top twig", as sample trees, but these weren't selected as
champion trees, but random stand height trees, where being accurate
to feet was adequate for the task. One further level of checks was
having a limited sample of the "sample trees" taken to the
mill for accuracy of volume measurements and tree grade (quality
issues, clear, knot free, extent of rot, etc.).
I have tried to relate all this in a non-defensive tone, as I feel
no need to rationalize my career as a forester. we did what was
needed to be done for the time, and did it with all our hearts.
Would I in retrospect, with omnicience, change anything? Oh, yeah,
you bet...but that's another story.
-DonRB
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TOPIC: Don Bertolette's early days in forestry
http://groups.google.com/group/entstrees/browse_thread/thread/24263f51fdac4d84?hl=en
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== 1 of 3 ==
Date: Tues, Jun 10 2008 12:36 pm
From: dbhguru@comcast.net
Don,
My friend, I certainly agree. You have no need to rationalize your
forestry days. The techniques you used were sufficient for the job
you were doing and your personal expertise in compensating for tree
form in height measurements served you well. Knowing you well, I
have absolutely no doubt of that. I am impressed with the methods
you employed to minimize the crown offset error, and on a more
general theme, I know plenty of foresters who can quickly estimate
DBH and multiple log lengths with great accuracy. I stand in great
respect of their abilities. The feathery tops of broad-crowned
hardwoods was just never part of the game.
My presentation of statistics about the accuracy of the tangent
method/rule is not in any way intended to point at field foresters
who are competently doing their work. If some of my email
communications have an underlying judgmental tone, I should
apologize for not being more careful. I have to admit that the
judgmental tone is unfortunately present and comes from my having
locked horns over the years with a small, but vocal minority of
folks who are incensed at being challenged by people outside their
field, as though they held exclusive rights to the body of knowledge
that involves measuring trees.
Innuendos aside, I usually find ways to temper my comments. At least
I hope that is the case. However, I note that passions can run high
on the subject. My buddy Will Blozan is inclined to engage in a full
frontal assault. I think you've commented on Will's unbridled
ferocity on an occasion or two. Just everybody be on guard. He who
challenges brother Will on what Will darn well knows he's especially
good at " 'ull git a can uv Georgia whoop-ass put on 'um."
In reflecting a little further on the subject, I think that both
Will and I see ourselves, validly or invalidly, as carrying the
banner for an area of knowledge that we see as getting bypassed or
trivialized when trees are seen through an economic lens. Having
just said that, though, I, in particular, have to be careful. In a
recent telephone conversation, Lee Frelich observed that ecologists
can get pretty sloppy with the max tree species heights when engaged
in what stands for purely scientific research.
Bob
== 2 of 3 ==
Date: Tues, Jun 10 2008 5:46 pm
From: DON BERTOLETTE
Bob-
Understood!
Re your phone conversation with Lee, it's been my impression that
forest ecologists don't measure the height of anything accurately
(well maybe a glass of beer...;>) just the presence or abundance,
in general they're more qualitative than quantitative. Less of a
physical science, more of an art.
-Don
== 3 of 3 ==
Date: Tues, Jun 10 2008 5:56 pm
From: DON BERTOLETTE
Bob/Ed?-
Whoever has done me the kindness of changing topic heading, has
missed my "early" days in forestry, when we surveyed with
a steel "topo" tape that was designed to work in
conjunction with a 'topo abney'; when we re-established our boundary
lines using a mountain transit (much like the original surveyor whom
we were 'mimicking'), and brushing line with a double bit ax and a
'Swede' (brand named Sandvik, it was a "safe" limbing
blade)...chainsaws weren't then accepted in the field (big heavy
brutes that we'd have fought having to carry).
But then that's another story...
-DonRB
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