Total volume estimates (fwd)
   Oct 15, 2003 17:46 PDT 


I'm forwarding a thought-provoking communication from Colby Rucker about calculating tree volume. Colby, Will, and I are always talking about ways to compute tree volume.

---------------------- Forwarded Message: ---------------------
From:    "Colby Rucker" ;
To:      <>;
Subject: Total volume estimates
Date:    Wed, 15 Oct 2003 00:29:09 -0400


I like to limit volume calculations to the main trunk and heavier leads so
that modeling of hypothetical cuts also provides a total in board feet.
This allows comparisons with the historic record of trees that scaled from
12,000 to more than 20,000 board feet.

I think it's unwise to add some trifling percentage for brush to the
carefully calculated trunk volume of some conifer. It become apples and
oranges, and guesswork always ruins good numbers.

All that said, there are some monstrous open-grown trees that wouldn't yield
much in board feet, but would displace a great deal in total volume.   Of
course, there's no decent way to calculate the volume of all the twigs and
branches, but it's all wood. One interesting exception was the Wye Oak, a
white oak that stood on Maryland's Eastern Shore. Although the total is
somewhat of a composite, we can get a pretty good idea of volume from the
weight of a fallen limb weighed at the feed mill across the road.

For any kind of argument, I'll say the volume reflects the tree as it was in
1953, with its major limbs intact. Although limbs were weighed that fell
after that, a great deal of live wood was removed from the tree, year after
year, in an attempt to reduce the weight and sail area of the crown. This
suggests that the major components maintained a fairly constant weight and
volume, despite unavoidable increases in diameter. I have not counted a low
limb weighing perhaps ten to fifteen tons removed as part of the state road
upgrade to auto traffic ca. 1912.

So, not perfect, but here goes anyhow:

10/6/53      Large limb fell across road 20.0   tons (est.)
Preston, pp. 110-111.
8/29/56      Largest limb fell                 30.0   tons (est.)
Preston pp. 5, 111.
6/10/84      Largest remaining limb fell 37.0   tons (feedmill)   Balto
Sun 3/20/85
1984          Emergency pruning               2.5   tons (est.)
Balto. Sun 3/20/85

6/6/02       Tree fell; main trunk            30.75 tons (crane?)
Balto. Sun 6/23/02
6/6/02       Limb wood                         19.25 tons (est.)
Balto. Sun 6/23/02
Total weight of tree                            139.50 tons

The estimates were probably from state foresters. The 1984 limb appears
heavier than the 1956 limb, which was immense, and the longest. This
suggests the estimate of 30 tons may have been somewhat low, or the limb was
simply less fully branched. The 6/6/02 limb wood tonnage is derived from an
estimate of 100,000 pounds for the entire tree. Leaves and rakings were not
included. 19.25 tons seems reasonable. Although less than the individual
weight of the three earlier limbs, much of the trunk was removed in one
wide-load piece, with portions of the heavier limbs still attached.

139.5 tons = 279,000 lbs. Dividing by 60 lbs./cu. ft. = ca. 4650 cu. ft.

Circumference at grade was 51 feet, cbh was 31' 10". The bottom of the

trunk was a hollow shell, accessed via an iron port. This air space, having
no weight, receives no volume from the 61,500 lbs. A broad void to four
feet up, tapering abruptly to ten feet up, it amounted to about 350 cu. ft..

Thus, quite conveniently, the total volume was 5,000 cubic feet.