| Species
Modeling and Big Tree Competition |
Robert
Leverett |
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Nov
08, 2002 05:52 PST |
Ents:
The return of
Dr. Tom Diggins to our list has been a blessing. Tom's
exploration and study of Zoar Valley makes it a legitimate 3-way
race
between MTSF, Cook Forest, and Zoar Valley for the honors of the
top tall
tree site in the Northeast - at least so. I suspect that there
is a site or
two in the lower Catskills in New York may offer us an
unexpected surprise.
We certainly haven't exhausted Pennsylvania of that state's
possibilities,
but short of a true surprise, the number of contenders is being
systematically eliminated, one by one. In a couple more years,
we'll have
sifted through all the candidates known to us except for remote
sites in the
Adirondacks, Greens, and Whites, which won't have high Rucker
Indexes
because of their severe growing conditions. In two years, what
will we have
likely concluded?
Well, we will
have concluded that there are regions, zones, and
sites of exceptional tree growth that cut across a variety of
habitats. It
could look exceedingly confusing, but we will also be able to
put tight
ceilings on those regions, zones, and particular sites with
respect to
various assemblages of species. We will be able to model various
species
reasonable well across a wide variety of site types, altitudes,
and
latitudes. We won't be at the point of teasing apart the
individual
contributions of the site and regional variables to exceptional
tree growth,
but we'll have a handle on some of the variables. That's the
direction we're
headed.
I had a long
conversation with Charlie Cogbill last night and as
always it helped me to recalibrate my thinking and give me a
better sense of
direction about where the research needs to go. Charlie
described the
extremely complex geology of the Deerfield River corridor from
South River
north into Vermont. Lots of useful minerals are tied up in the
rock
formations, which can change drastically over sort distances. So
the
Deerfield River corridor becomes an excellent laboratory in
which to study
site variables that have dramatic impacts on tree growth.
Elevation changes
are commonly on the order of 500 to 1000 feet, but in the Dunbar
Brook area
the mountains drop from 2,841 feet down to the Deerfield at 900
feet.
Moisture is probably the highest in the state. I suspect between
50 and 55
inches annually on the sides of the Hoosac Mountain Range. There
are all
aspects and gradients. So it is now a question of gathering the
data in
systematic ways to insure comparability. Putting in study plots
is
essential. I can't just range over the landscape shooting the
most
conspicuous trees, although up to now, that method has been
indispensable in
seeing the big picture. I'll still roam around, but will also
rely on study
plots. The data base must become much more fine-grained.
It is time for
pats on the back for my fellow Ents and especially to
the magnificent 8. Without the veritable deluge of accurate tree
heights,
the exceptional tree growing sites would not have stood out so
prominently
and meaningful comparisons would not have been possible between
sites and
regions we've been studying. In Massachusetts, sites like
Bullard Woods, Ice
Glen, the Bryant Homestead, MTSF, MSF, Mount Tom, Skinner State
Park,
Arcadia, etc. would just be sites with conspicuous trees. An
exceptional
girth or two would be noted for each site and that would be
about it.
For us, the
breakthrough came from employing the simple combination
of laser and clinometer along with a heavy dose of plane
trigonometry. The
results have been startling. The prior method of aiming a
clinometer at a
tree's canopy at a 100-foot distance and reading a percent slope
scale
produced results that were far too crude to allow us to
accurately
distinguish differences in tree growth potential for individual
species and
across species. The ashes, beeches, and sugar maples blended
together. There
are real differences. Were we still using the older measurement
method, we
would continue making errors that swamp even moderate
differences, let alone
small, subtle ones. So we can be justifiable proud of the
engineering of
better techniques. Our persistence has paid off. Besides
ourselves, the
future beneficiaries will be the scientists and foresters who
need highly
accurate tree measurement data to crank into their models.
They'll have it,
courtesy of the Eastern Native Tree Society.
Bob |
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