== 8 of 11 ==
Date: Tues, Nov 13 2007 4:25 pm
With this discussion of what are the biggest volume trees, some of
you may wonder how big a tree needs to be to have 1000 cubic feet of
wood. Most of the trees are better modeled as a paraboloid, but a
simple calculation can give you a ballpark figure if you consider
the trunk to be conical in shape.
The volume of a cone is 1/3 pi r^2 h if the volume is 1000, and the
height of the trunk (not the tiny upper branches) is 100 feet, then
the radius of the tree must be 3.09 feet, or it must have a girth of
19.41 feet. If the tree trunk was 120 feet high, then it must have a
radius of 2.82 and a girth of 17.72 feet. Depending on the taper,
and other factors a tree may need a radius larger than this or even
smaller to reach 1000 cubic feet.
So what trees are 100 feet tall and twenty feet in circumference?
Some of the silver maples Dale, Anthony, and I measured in the
Allegheny Islands River Wilderness, PA are almost there...
== 9 of 11 ==
Date: Tues, Nov 13 2007 4:29 pm
From: "Will Blozan"
Great illustration! A 1000 cubic foot tree is really big! In
think hardwoods will be hard to find regularly in that class.
== 11 of 11 ==
Date: Tues, Nov 13 2007 5:35 pm
One of my projects is to test the paraboloid hypothesis. I have most
of the math worked out. More to come later. Oh yes, another measure
of 1000 cubes is or almost is the Grandfather Pine in Monroe SF. At
14 feet in girth at 4.5 feet and 143.3 feet in height, it weighs in
at 967 cubes, courtesy of Will's climb. We'll have many more
examples when i can get out with my trusty TruPulse 360.
== 1 of 1 ==
Date: Tues, Nov 13 2007 5:47 pm
It would be nice to have a little table of useful approximations or
rules of thumb like how big is 1000 ft^3. Another one that is useful
I think, is how big of an area really is 1 acre. I mentioned it in
one of the posts about McConnel's Mills. How far out from your
position would a 1 acre circle extend. An acre is a circle just
under 120 feet, or 40 yards in radius. I know I rely on such
approximations to better gauge what I am seeing in the forest. I am
not sure what other quick formulas would be useful in the field.
Diameter is just over .3 times the girth. Radius is half that. I am
sure there are other rules of thumb that are useful or would be
useful if I knew them.
TOPIC: From the Formula Factory
== 1 of 1 ==
Date: Fri, Nov 16 2007 9:10 pm
I have been thinking on ths some more, with the end toward
good rules of thumb for use in the field. Below I noted that 1000
ft^3 was a tree 20 feet circumferrence x 100 feet high, or 18 feet
circumference x 120 feet high. Good start.
The formula for a cone is 1/3 pi r^2 h = volume , well 1/3 pi is
approximately 1.05, which is approximately 1, so the formula for
purposes simplifies to Volume = r^2 h. r is the radius, which is
equal to circumference/ 2pi which is approximately r = girth/6.3.
Volume = r^2 h = (girth/6.3)^2 h which is smething you can do in
head or with a few punches of your calculator while in the field.
(The notation ^2 means something is squared, the ^ showing it is an
exponent.) radius squared x height = volume = (girth/6.3) squared x