Jack, Ed, ENTS:
A few more thoughts/responses about white pine growth/measurement:
As for the capability of people 200 years ago to measure the
heights of standing trees‹that is unquestioned. The main question is
³did they?² Often the reports of these very tall trees came from
loggers, who, although I have worked as a logger at various times in
my life, and believe at its best it can be a noble profession, I have
not seen them much interested in taking precise measurements of any
trees before they cut them down, nor in measuring trees after,
especially when the top of the tree shatters and it would have to be
carefully reconstructed to get an accurate measurement. I would think
that if some one with a ³scientific² mind did careful measurements,
these would have some down to us in a quite different way than in the
style I have seen them, i.e. ³early lumberman reported thatŠ.² etc.
One thing I have seen in reports from early lumbermen of the trees
they cut down, is a focus on data such as, ³at a height of 120 feet
the tree had a top diameter of 20 inches,² or some such thing. They
report this way because they are interested in how many logs the tree
has produced.
So here is what MAY have led to some of these reports. If a
gigantic white pine is 200 feet tall, and at a height of 160 feet
still has a diameter of something like 20², someone could read that
report and say, ³Oh at 160 feet the tree was still 2² in diameter, so
then it must have been 250 feet tall. Yes, many younger white pines
have a rather gradual taper. A tree 20² in diameter in a young forest
can be 100¹ tall. But with very old trees, the taper at the top can
be very, very rapid. A very old white pine could have a diameter of
20² near the top, and be only 40 feet taller, or perhaps much less.
As for amount of light required‹the amount of crown exposure above
adjacent trees‹for white pines to make maximum growth: This is an
important factor. Tree crowns are usually classified by foresters into
basically 4 crown classes: dominant, co-dominant, intermediate, and
suppressed. Added to this I believe should be ³emergent.²
A dominant crown has a good portion of its crown exposed above the
surrounding trees, but this does not require that the crown be
³emergent,² meaning far above the surrounding trees as many white
pines in NE, especially on ridges where the hardwoods they are often
mixed with, cannot really compete.
The next crown class, the co-dominant, is a bit lower in relation
to the surrounding trees. Here the crowns of a group of trees are more
or less equal in height, but they do have good space between them, and
they receive plenty of direct sunlight. An issue here is also grown
length. A dominant crown will be somewhat longer‹extend further down‹
than a co-dominant tree.
The next crown class is the intermediate. Here the tree is closely
pressed on all sides by other trees. In some cases the crown can be
at nearly the same height or more usually somewhat lower than those of
its competitors. The crown is narrow, and depending on the species
and the kinds of trees it is competing with, it can be either rather
short, or rather thin foliaged.
White pines are classed as a moderately intolerant tree, meaning that
they require more direct sunlight than a tolerant tree. This means
that to grow well in height, a white pine needs to be in either a
dominant or a strong co-dominant crown position. To grow well in
diameter, it should be in a dominant crown position.
Norway spruce is more tolerant than white pine, and therefore can
grow better in an intermediate or marginal co-dominant crown position
than white pine. White pines that are in an intermediate crown
position, or perhaps also in a marginal co-dominant crown position,
usually will lose vigor and be overtopped.
Well, sorry, I see I am giving too much background here. The basic
answer to the question about the amount of crown exposure a white pine
needs to grow the tallest is dominant or strong co-dominant. Emergent
crowns get so much light that a great deal of the growth energy of the
trees goes into creating a very large spreading crown with heavy
branches. White pines, and most other forest trees grow tallest when
they are in competition with other trees as in the usual dominant or
co-dominant positions.
Finally, occasionally a white pine tree growing far above the
surrounding trees did not in fact grow as an emergent tree, but grew
in a forest with other trees in a dominant or co-dominant crown
position, and then, either because the surrounding trees were removed,
or died for some reason, this tree will stand in a very, very strong
emergent position. That does not mean that it grew to its present
height as an emergent.
--Gaines McMartin
