Date: Thurs, Nov 13 2008 6:39 pm
From: "Edward Frank"
We measure the volume of a tree by measuring the diameter or girth
of the tree at different heights. The length between the
measurements, and the respective girth or diameter at the top and
bottom of that segment is used to calculate the volume of that
segment of the tree. These segments are treated like cones with
their tips cut off a frustum of the cone. The formula for
calculating the volume of the frustum is as Bob stated below. So you
stack all these sections together and that gives you the volume of
the tree. The diameters are measured by actually climbing the tree
or using various electronic instruments to measure the girth from
the ground. There are many documents about the volume measurement
process on the website http://www.nativetreesociety.org/measure/index_measure.html
, and well a a brief outline in the ENTS Tree Measuring guidelines http://www.nativetreesociety.org/measure/Tree_Measuring_Guidelinesrevised.pdf
.
Ed Frank
 Original Message 
From: dbhguru@comcast.net
To: entstrees@googlegroups.com
Sent: Thursday, November 13, 2008 8:36 PM
Subject: [ENTS] Frustum of Cone
A section of a geometric solid like a cone formed by passing
horizontal parallel planes through the solid generates a frustum.
Practically speaking when applied to tree trunks, frustums are just
sections of the trunk. There are formulas to compute the volumes of
frustums of different solids. If D1 and D2 are diameters of the top
and bottom sections and H is the height of the frustum, the volume
is given by:
V = H*PI/12*[D1^2 + D2^2 + D1*D2]
Bob
