2409.12_20
Page 1 of 7
FOREST SERVICE HANDBOOK
WHITE RIVER NATIONAL FOREST (REGION 2)
GLENWOOD SPRINGS, CO
FSH 2409.12 - TIMBER CRUISING HANDBOOK
CHAPTER 20 – ESTIMATING TREE VOLUME AND WEIGHT
Supplement No.: r2_white_river_2409.12-2001-1
Effective Date: July 16, 2001
Duration: This amendment is effective until superseded or removed
Approved: MARTHA J. KETELLE
Forest Supervisor
Date Approved: 07/10/2001
Posting Instructions: Supplements are numbered consecutively by Handbook number and
calendar year. Post by document; remove the entire document and replace it with this
supplement. Retain this transmittal as the first page(s) of this document. The last supplement to
this Handbook was 2409.12-94-1 to FSH 2409.12, 10 and 20.
New Document(s):
2409.12_20
7 Pages
Superseded Document(s):
(Amendment Number and
Effective Date)
2409.12, 10 (November 1, 1993 WR Supplement
1 Page
#2409.12-94-1)
2409.12, 20 (November 1, 1993 WR supplement #
2409.12-94-1)
7 Pages
Digest:
15.12o - Removes obsolete White River direction in FSH 2409.12, chapter 10.
22.--1 through 22.3--6 - Content remains the same – separates chapter 10 and updates format to
FSH 2409.12, chapter 20.
WHITE RIVER SUPPLEMENT: 2409.12-2001-1
EFFECTIVE DATE: xx/xx/2001
DURATION: This amendment is effective until superseded or removed
2409.12_20
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FSH 2409.12 - TIMBER CRUISING HANDBOOK
CHAPTER 20 – ESTIMATING TREE VOLUME AND WEIGHT
22 – TREE VOLUME DETERMINATION
22.3 – Estimating Tree Defect and Net Tree Volume
The following policy will be used for cruising and defecting Aspen, which will be offered for
sale as products other than logs (POL). Approved appraisal points for POL are listed in FSH
2409.22, Section 71.1. Whether the timber products are processed as wafer board or other
products in the local area is not a consideration in determining the manner of estimating tree
defect.
The objective of cruising and defecting is to determine the net amount of usable fiber, which a
given tract of timber can produce. The cruiser should assume bucking of trees for maximum
utilization. Use Chart A (below) as an aid in determining the percentage of defect in trees.
Applicable defect shall be determined for rot, voids, scars, cankers, crook, and sweep. No defect
shall be deducted for stain.
The guidelines in this supplement shall be used to prepare cruise plans.
22.31a – Volume Distribution in Trees
Piece Length. Cruising will be by 8 1/3’ pieces. A piece must be at least 8 1/3’ long to be
considered merchantable, but any length greater than 8 1/3’ will also be considered
merchantable. For example, a piece that is 10’ or 12’ long and containing no other defect is
considered 100% merchantable.
Percent Net of Gross. The minimum piece size (8 1/3’) referred to above may contain up to
50% defect and still be considered a merchantable piece.
Chart A: Percentage Distribution of Tree Volume by 16-Foot Segments
and Segment Position (Based on a Form Class of 80)
8 Foot Piece
Position
16.5’
1
Butt
2nd
3rd
4th
5th
100
---------
Aspen: Number of 16 Foot Pieces
24.8’
33.0’
41.2’
49.5’
1½
2
2½
3
Percent of Total Tree Volume
74
58
51
45
26
42
36
33
----13
22
-----------------
57.8’
3½
66.0’
4
4½
39
31
22
8
---
37
28
21
14
---
33
26
20
15
6
WHITE RIVER SUPPLEMENT: 2409.12-2001-1
EFFECTIVE DATE: xx/xx/2001
DURATION: This amendment is effective until superseded or removed
2409.12_20
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FSH 2409.12 - TIMBER CRUISING HANDBOOK
CHAPTER 20 – ESTIMATING TREE VOLUME AND WEIGHT
22.31b – Rots
Phellinus tremulae (fomes ignarius) is the most common fungus encountered in Aspen. Rot is
usually not a deductible defect except when it meets one of two criteria:
1. Rot is so well advanced that a void is present or the fiber is so loose that it may be
literally removed by the handful. When this condition is evident, an appropriate
length deduction should be taken to reflect this defect.
2. If a cross-section of the bole would show that 50% or greater of the cylinder is
affected by ‘soft’ rot. Soft rot is defined as rot, which is so advanced, that it may be
easily penetrated when probed with a knife blade. As noted under criteria #1 above, a
length deduction should be made to the affected portion of the bole. This deduction
reflects portions of the log, which would shatter when subjected to the stress of a
debarking operation.
The presence of soft rot is not deductible in and of itself. Soft rot when not advanced contributes
fibrous material used in making wafer board. Therefore, soft rot is not arbitrarily deducted in
amounts comprising up to 50% of the cylinder diameter.
The presence of large, well-developed conks is certainly an indicator of rot, but whether it is
deductible as stated in criteria 1 or 2 noted above is best determined by use of an increment
borer, chainsaw or the experience of the cruiser. It is appropriate for cruisers and check cruisers
to use the above criteria as an aid to determine defect.
For example, if it is determined that the lower 2 feet of a 2 ½ log tree meets the above criteria,
the defect for that tree is 2/16 x 51 = 6.38% or 6% defect.
To help in gaining uniformity in defecting Aspen displaying Phellinus tremulae conks, the
following standards shall be used:
1. Aspen showing one average size (approximately 4” across) or two smaller conks per
tree – NO DEFECT.
2. Aspen showing two average size conks located on separate portions of the bole or
several smaller conks – NO DEFECT. Discretion should be used in making this
determination. Defect may be applied, but not as a general rule.
3. Aspen showing three or more average sized conks or numerous (5+) smaller conks on
the bole should be defected by making a length deduction between the conks in
addition to two feet above and below the conks.
WHITE RIVER SUPPLEMENT: 2409.12-2001-1
EFFECTIVE DATE: xx/xx/2001
DURATION: This amendment is effective until superseded or removed
2409.12_20
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FSH 2409.12 - TIMBER CRUISING HANDBOOK
CHAPTER 20 – ESTIMATING TREE VOLUME AND WEIGHT
These defecting guidelines are not intended to be ‘absolutes’. Each tree must be examined
individually considering these guidelines while considering the presence of other factors such as
scars, cankers, crook, and sweep. The presence of one or more of these factors may indicate that
more severe deductions for defect are appropriate.
22.31c – Sweep and Crook
Minor amounts of crook and sweep are allowable and result in no defect deduction. If a tree
contains more than a minor amount of crook or sweep, a deduction should be made.
To determine of a crook or sweep is ‘major’, imagine a tape or string stretched tightly center to
center between the ends of a minimum piece (8 1/3’ long). If the tape deviates from the edge of
the piece, excessive crook is present. This piece will not go through a debarker and must be
culled.
With sweep, when the tape is stretched tightly center to center between the ends of a minimum
piece (8 1/3’ in length) without ‘major’ crook and sweep noted above, the cruiser should not cull
the piece.
See exhibits 1 and 2 that further illustrate these points.
22.31d – Missing Wood
Voids. A deduction must be made for missing material. Mechanical scars usually cause this.
Use standard scaling and cruising procedures to determine defect. Use pie cuts, length
deductions or portions of a length cut to determine the percentage of defect. For example, a void
affecting ½ of a four-foot piece on the butt log of a two-log tree would be calculated as follows
(refer to Chart A):
58% X 25% 0.5 = 7.25% rounded to 7%
Cankers and Burls. Only cankers caused by Ceratocystis fimbriata (black canker or target
fungus) are deductible. This canker forms successive annual rings of hard, dry callus tissue,
which cannot be used in the wafer board process.
Minor cankers involving ¼ or less of the circumference of the bole indicate – NO DEFECT.
Cankers involving more than ¼ or less of the circumference of the bole should be defected with a
length cut. Burls are handled in the same manner as cankers.
Exhibit 3 displays an example of defecting for cankers or burls.
WHITE RIVER SUPPLEMENT: 2409.12-2001-1
EFFECTIVE DATE: xx/xx/2001
DURATION: This amendment is effective until superseded or removed
2409.12_20
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FSH 2409.12 - TIMBER CRUISING HANDBOOK
CHAPTER 20 – ESTIMATING TREE VOLUME AND WEIGHT
Exhibit 1 – Crook
In this case, the lower 8 feet of the tree contains crook whose imaginary string line diverges from
the edge of the bole and is therefore unusable or cull. The upper 4 feet of this piece should be
‘attached’ to the next log and the defect calculated as follows: 74% X .25 – 18.50% rounded to
18%. The principle of bucking for maximum utilization is applied in this illustration in that only
the lower 4 feet of the butt log will be lost, while the upper 4 feet of the butt log should remain
attached to the second log.
WHITE RIVER SUPPLEMENT: 2409.12-2001-1
EFFECTIVE DATE: xx/xx/2001
DURATION: This amendment is effective until superseded or removed
2409.12_20
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FSH 2409.12 - TIMBER CRUISING HANDBOOK
CHAPTER 20 – ESTIMATING TREE VOLUME AND WEIGHT
Exhibit 2 – Sweep
In evaluating sweep, the imaginary string line may diverge from the log by up to 2 inches
resulting in a merchantable piece.
WHITE RIVER SUPPLEMENT: 2409.12-2001-1
EFFECTIVE DATE: xx/xx/2001
DURATION: This amendment is effective until superseded or removed
2409.12_20
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FSH 2409.12 - TIMBER CRUISING HANDBOOK
CHAPTER 20 – ESTIMATING TREE VOLUME AND WEIGHT
Exhibit 3 – Cankers and Burls
For example, a canker 4 feet long is located at the bottom of the second log of a 2 ½ log tree and
canker 5 feet long is located at the top of the same log. Both cankers involve more than ¼ of the
circumference of the bole. By taking a length cut, the remaining ‘ piece’ is only 7 feet long (16 –
4 – 5 = 7) making the entire second log cull. This is equivalent to 36% defect for the tree.