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dbhg-@comcast.net |
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Aug
18, 2007 19:16 PDT |
ENTS,
With my Holyoke house sold, my toe
on the mend, and being semi-retired, it is time to for me return
to working on the dendromorphometry guide. So, today I began by
modeling a northern red oak in Monica's woods. The statistics
for Monica's oak are height = 103.2 feet, CBH = 5.8 feet. The
oak is one of several on Monica's land that exceed 100 feet. The
tree presents an exceptionally inviting target from the deck of
the house. It is an exercise in modeling in comfort. The trunk
of the oak is only 67 feet away at eye levelfrom the deck and
the height from tree base to eye level from the deck is 31 feet.
The tree is fully visible except for the very tips of the
broccoli-shaped crown.
On modeling the oak with the
Macroscope 25, I calculated 147.1 cubic feet of trunk volume
with allowance for the crown as will be explained. I was able to
model past the first point of branching. It occurs between 56
and 58 feet above base. From 58 feet, I followed the larger of
the trunks, regarding it as the main trunk, up to 67 feet where
there was a second branching and there the continuation is less
distinct in terms of a main trunk. So at 67 feet, I cheated and
used a straight conical volume to the top although I fully
acknowledge that the form is hardly conical. After getting the
147.1 modeled volume, I calculated the concical volume based on
the CBH just above the root collar and the full height. The CBH
at that point is exactly 7.0 feet. The conical volume for a
height of 103.2 feet and a diameter at 1 foot of 2.22 feet is
also 147.1 feet. Yes, this is a coincidence, but I think the
closeness is revealing. I believe that the conical volume
calculated for full tree height
ht and CBH at just above the root collar will usually equal or
be slightly more than the full modeled volume for most
straight-trunked, middle-aged eastern trees be they conifer or
hardwood. For older trees, the conical volume is likely to
understate the modeled volume for some forms and overstate it
for others. If there is a big root flare, then the volume will
be overstated.
Applying the concept of conical
volume just above root flare to the Grandmother tree in Pack
Forest, one gets 997 cubic feet - which is too much. But
Grandmother has a big root flare. Using Grandmother's diameter
at breast height in the cone volume formula, you get 760 cubes,
which slightly understates Grandmother's volume. I am doubtful
that I modeled the Grandmother tree sufficiently accurately. The
mosquitoes were very bothersome and I could have misread the
reticle, swatting with one hand. Monica and I will return to the
Daks in late October, if not sooner, and the mosquitoes will be
gone. I'll have no excuse then.
For the large Dunbar Brook hemlock
in Monroe State Forest, the reverse pattern is true. The Dunbar
Tree has been modeled to 720 cubic feet of trunk volume.
However, the conical volume taken to a broken top height of
116.3 feet with a girth at that point of a foot and a root
collar girth of 14.3 feet gives 705 cubes, which falls just
short. The tree was probably about 123 feet tall before the
dieback. I remembered it when it first started to die back and
got a height of 122 feet then. Taking a height of 122 feet, the
conical volume would be 662 cubes and the modeled volume would
be 721 cubes. The bulging hemlock trunk causes the conical
volume to be significantly understated. The form of the Dunbar
hemlock trunk is much more columnar than that of the white
pines.
We have modeled the huge Dunbar
Brook Grandfather white pine to a volume of 932 cubes. The
conical volume using its 145-ft height and 16-foot circumference
just above the root collar yields a volume of 985 cubes. I will
make a prediction at this point that for the vast majority of
white pines, the conical volume using full tree height and girth
just above the root flare will overstate the volume typically by
5% to 10% and sometimes more. But hemlocks are a different story
and Will Blozan well understands hemlock architecture. I look
forward to his final Tsuga report.
Bob |
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