Tallest Trees in Ravines  Bob Leverett
  Jul 08, 2003 05:31 PDT 

Lee:

   I could have included lat and long attributes to the matrix for the Mass
sites, but there would have been little variation in those variables for the
included data points. However, in the future, I'll expand the variable list to
include other WP sites along with latitude and longitude.

Moisture has me buffaloed. I just don't know how to get good, local
precipitation data. It is virtually certain that the variation among the sites on
the list is at least 10 inches and quite probably 15.

   The tallest trees are in ravines or at the base of hills/ridges where water
is more abundant and protection from wind more reliable per your prior
observations. Flats and other more exposed areas just don't yield the tall
trees here in the Northeast and that conclusion will hold up with few
exceptions. However, I think we need more sophisticated landform variables to
adequately reveal the relationships to terrain. In a couple of spots where the
exposure is south-facing, the trees are at the bottom of a ravine so that
moisture is more reliable. I would be truly surprised to find a 140-footer well
up on the side of a south-facing ridge.

   Do you want to include a few early successional species in the analysis,
e.g. cottonwood?

Bob
RE: Tallest Trees in Ravines  Lee E. Frelich
   Jul 08, 2003 07:19 PDT 

Bob and Gary:

What really matters is the evenness of moisture supply to the roots, which
is a function of rainfall amount, evenness of precipitation (or its
compliment drought frequency), soil texture, aspect, and evaporation rate.

Perhaps we can develop an evenness index based on all those factors. The
best way to do that would be to take tdr (time domain reflectometry) soil
moisture probe used several times throughout the summer on different types
of sites, and then create and apply the evenness index (using terrain shape
index and terrain site index, and their relationship to water supply) to
all sites.

To answer Bob's question, we should probably include some intolerant and/or
early successional species in those that we study.

Lee
RE: Tallest in ravines...  eay-@comcast.net
   Jul 09, 2003 11:01 PDT 

Don't ignore the fact that ravines are a hard place to log. It may well be
that the main reason the tallest tress are found there is because it is very
difficult to remove them. The presence of good steady supplies of moisture
will certainly be a part of the scenario, but in an "old growth" stand prior
to logging, I strongly suspect the average moisture levels both in the soil
and in the air were higher than at any time since.

_________________________________________
E. Daniel Ayres
ZundapMan
ICQ#: 33685597
Re: Tallest in ravines...  dbhg-@comcast.net
   Jul 13, 2003 10:38 PDT 

Dan:

   When we use the term ravine, we aren't referring to just the intimidating
places, but we are also including shallow, accessible depressions. We should
probably use more descriptive language or at least I should.

   The river gorges have the worst of the terrain and did deter logging where
land tracts were small and held in private hands. Inaccessibility is the
explanation for survival of the old growth pockets in Massachusetts that have
good timber. More on this subject in a future e-mail.
Re: Tallest in ravines...  dbhg-@comcast.net
   Jul 14, 2003 19:25 PDT 

Dan:

   Some more thoughts on habitat for growing trees. Across the New England
countryside there are numerous places supporting either isolated trees or small
patches of trees that have been left alone for a century or more. Property
boundaries, conservation properties, private estates, public forests, etc. have
plenty of trees 100 to 200 years old. A lot of urban forests are quite mature
now.

   We are studying tree growth in all the above mentioned places with the
eventual goal of determining regional/local maximums. So far observations and
data show that ravines commonly produce taller trees. The reason is not hard to
establish - the water supply is more reliable and soil depth often greater. It
really is all about soil and water.

   Incidentally, Dr. Lee Frelich's list of inputs variables that govern maximum
growth is holding up very well in terms of explaining what produces fast and
sustained tree growth. It is just that some of the variables reach maximums in
places that timber producers originally downplayed because of limited
accessibility. Boulder fields on the sides of mountains were generally thought
to be poor tree growing habitat and indeed many are, but then there are also
many exceptions. The boulder field habitats were at first an enigma, but then
we realized that concave areas of mountain sides hold the water. Boulder fields
can contribute to metering the water flow.

    What keeps the tree growth research interesting are the frequent surprises
that go against conventional wisdom. For instance, American basswood is
ordinarily a slender forest tree in southern New England. A forest-grown
basswood over 30 inches dbh is truly large. Most I have measured are 16 to 24
inches dbh. However, the basswoods do grow tall in the mountains. I've measured
them to 124.5 feet in height in the Berkshires. I've measured quite a few over
100. In fact hundred-footers are not a novelty. So our basswoods grow tall, but
stay slender.

     You might think that farther north overall size of the basswood would come
down, but in the upper Mid-west, the American basswood becomes a noticeably
larger forest-grown tree. It loses a little in height, but more than makes up
for the vertical loss with a considerably more robust girth. I was amazed at
the basswoods in the Porcupine Mountains of Michigan's upper peninsula. The
basswoods are simply bigger. I'm not aware of any subspecies for basswood.

      By contrast, eastern hemlocks behave quite differently across their north-
south range. Hemlocks reach their greatest dimensions in the southern
Appalachians. The Smokies grow monsters. However, as one goes northward, the
hemlock's dimensions gradually diminish. Yet the hemlock is considered to be a
northern species and in terms of broadness of range and abundance, it is. It
seems strange that the largest are found with 20 to 100 miles of the southern
end of the range of Tsuga.

      White pine behaves even differently. That species seems to be able to
maintain a relatively constant maximum volume over a greater range of latitude.
The southern trees are a little taller, but the northern trees seem to catch up
by getting a little fatter. The white pines of the Smokies may be an exception.
That remains to be seen.

      Going from east to west, the black cherry seems to reach maximums of
development to the west. Western Pennsylvania and New York produce large
imposing black cherries. The Smokies produce whoppers. Both areas are far west
on New England.

       As we add data, we develop a more complete picture of each species.
Surprises will likely come by the buckets-full as we Dr. Tom Diggins adds data
from Ohio. Hopefully, Lee will have some additional comments on this
fascinating subject.

Bob