Species Modeling and Big Tree Competition    Robert Leverett
   Nov 08, 2002 05:52 PST 

        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

        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.