More modeling   Robert Leverett
  Nov 02, 2005 05:44 PST 

Will, Jess, Lee, et al:

    As we gather more volume data on the white pines and eventually
other species, it should be possible to develop standard species
profiles to help us better understand how a species growing in a forest
environment changes its shape over time. For example, we all see the
dominate symmetry of young white pines in a stand. We also see the
unruly shapes of field pines. We observes that as forest-grown pines get
old, they develop a more columnar form, but some much more so than
others. For pines in the 150-foot class, we expect that most of the
volume will be in the first 100 feet and all these observations are
sound. What we don't know is how to quantify what we see and if there
are rules of thumb that we can apply. So, despite all the modeling we
have done, there are more loose ends than tied knots. The reason for the
plethora of loose ends is that we've had to concentrate on just how to
get ball park volumes. But now we have the RD 1000, and with that little
beauty comes the possibility of developing models that reflect how
volume is built over time. It is just pure unfunded research - no
commercial motivations. So progress will be very slow. But progress will

    A question that I recently posed to myself was this. Is the volume
of a trunk from a diameter point of x inches to the top of the tree
predictable within reasonably tight boundaries for a species like white
pine? Hemlock, etc.? For instance, let's say I scan up the trunk of a
tall pine to a point where measurements with the RD 1000 suggests that
the trunk has narrowed to 18 inches and from there continuously narrows
in a reasonably conical shape. If the visibility is poor and I can't get
satisfactory diameter measurements at higher points, can I make a
reasonable prediction of the remaining volume? Well, a couple of days
ago, I thought I could. But looking at my data, I am puzzled at the
patterns I am seeing. Three possible explanations follow.

   (1) There is a significant difference in the proportions for younger
slimmer pines as compared to larger older one for how much volume can be
expected at and above a diameter of 18 inches.

   (2) The amount of retained limb mass, courtesy of the pine's growing
environment changes trunk curvature sufficiently to create discernibly
distinct populations necessitating the introduction of form classes
early on.

   (3) My data suck (Oh well)

   Starting this weekend, I will begin sharing much more detail on
individual tree modelings and measurements with those of you on the
list. I've already been doing that with a select few off this list, not
wanting to drown the rest of you in numbers. But now with Pamela Briggs
on the list and finally getting my dear partner Monica Jakuc signed up
on Topica, there can be a welcome counterbalance of list topics. So, I
won't feel guilty in dumping tons of data onto the list in hopes that
more supple brains than mine can help the faithful few tree modelers
make sense out of the seemingly endless patterns. Dr. Tom Diggins once
observed that ENTS is an incredible brain trust. It only makes sense to
make use of it. So beware, folks, the numbers are going to roll.


Robert T. Leverett
Cofounder, Eastern Native Tree Society