Trees in Ravines
08, 2003 05:31 PDT
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,
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
observations. Flats and other more exposed areas just don't
yield the tall
trees here in the Northeast and that conclusion will hold up
exceptions. However, I think we need more sophisticated landform
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
up on the side of a south-facing ridge.
Do you want to include a few early
successional species in the analysis,
Tallest Trees in Ravines
08, 2003 07:19 PDT
Bob and Gary:
What really matters is the evenness of moisture supply to the
is a function of rainfall amount, evenness of precipitation (or
compliment drought frequency), soil texture, aspect, and
Perhaps we can develop an evenness index based on all those
best way to do that would be to take tdr (time domain
moisture probe used several times throughout the summer on
of sites, and then create and apply the evenness index (using
index and terrain site index, and their relationship to water
To answer Bob's question, we should probably include some
early successional species in those that we study.
Tallest in ravines...
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
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
Tallest in ravines...
13, 2003 10:38 PDT
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.
Tallest in ravines...
14, 2003 19:25 PDT
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
boundaries, conservation properties, private estates, public
forests, etc. have
plenty of trees 100 to 200 years old. A lot of urban forests are
We are studying tree growth in all the above
mentioned places with the
eventual goal of determining regional/local maximums. So far
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
accessibility. Boulder fields on the sides of mountains were
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.
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
ordinarily a slender forest tree in southern New England. A
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
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
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
basswoods are simply bigger. I'm not aware of any subspecies for
By contrast, eastern
hemlocks behave quite differently across their north-
south range. Hemlocks reach their greatest dimensions in the
Appalachians. The Smokies grow monsters. However, as one goes
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
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
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