| Hardwoods
at Arnold Arboretum |
Andrew
Joslin |
| Nov
25, 2006 16:21 PST |
I've posted photos of some particularly fine hardwood trees in
the
Arnold Arboretum, Jamaica Plain, Massachusetts.
http://www.flickr.com/photos/naturejournal/sets/72157594391735531/
No measurements made today but the Silver Maple is said to be
126'.
It looks less than that, one of these days I'll get myself a
clinometer. Have any of the Massachusetts ENTS measured this
tree? Be
curious to know what you got. I'll add DBH to the photos when I
get
the time to make the measurements.
Enjoy,
Andrew |
| RE:
Hardwoods at Arnold Arboretum |
Robert
Leverett |
| Nov
27, 2006 06:00 PST |
Andrew,
I have seen the Silver Maple at Arnold
Arboretum. It is less than
126, maybe around 100. Possibly 105. I was giving a lecture for
the
Arboretum and didn't have an opportunity to measure the tree
directly.
I hate to sound negative, but if you get a clinometer
without a
companion laser and scientific calculator with trig functions,
you will
be doomed to making the same kinds of measurement errors that
lead to
common height overstatements like the 126. With a clinometer
alone, you
can't determine spatially where the top of a tree is relative to
its
base, and as a consequence, you are always measuring to a
projected top.
There is a method that helps locate the top relative to the
base. It is
called cross-triangulation and is explained on the website, but
the
method is difficult to apply in the field except for trees that
have a
distinctly visible high point that can be seen from two
directions with
sufficient angular separation to allow cross-triangulation.
If you get a chance, come over to western Mass
and we'll measure some
trees together. I'll let you test several lasers. However, I
will say
right off the cuff, my favorite is the Nikon Prostaff 440. If
you get a
bargain on one, grab it.
Bob
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