2409.12_10
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FOREST SERVICE HANDBOOK
JUNEAU, ALASKA
FSH 2409.12 – TIMBER CRUISING HANDBOOK
CHAPTER 10 – PRINCIPLES OF MEASURING TREES
Supplement No.: R-10 2409.12-2016-1
Effective Date: April 1, 2016
Duration: This supplement is effective until superseded or removed.
Approved: /s/ Beth G. Pendleton
BETH G. PENDLETON
Regional Forester
Date Approved: April 5, 2016
Posting Instructions: Supplements are numbered consecutively by Handbook number and
calendar year. Post by document name. Remove entire document and replace with this
supplement. Retain this transmittal as the first page of this document. The last supplement to
this Handbook was R-10 Supplement 2409.12-2005-2.
New Document(s):
2409.12_10-2016-1
5 pages
Superseded Document(s) by
Issuance Number and
Effective Date
2409.12_10 (2409.12-2005-2, 8/2/2005)
2 Pages
Digest:
14.12n - Adds Young Growth Bark Thickness Ratios.
14.2 - Modifies Measuring Broken Trees
R-10 SUPPLEMENT 2409.12-2016-1
EFFECTIVE DATE: 4/1/2016
DURATION: Effective until superseded or removed
2409.12_10
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FSH 2409.12 – TIMBER CRUISING HANDBOOK
CHAPTER 10 – PRINCIPLES OF MEASURING TREES
14 – MEASURING THE TREE
14.12m – Old Growth Trees without Bark
For trees without bark, use the following bark thickness ratios to calculate Diameter at Breast
Height (DBH).
Species
Spruce
Hemlock
Western Red Cedar
Alaska Yellow Cedar
Bark Thickness Ratio
.96
.92
.95
.95
DBH = Diameter without bark/bark thickness ratio.
1. Example 1:
A spruce tree has no bark at DBH (4.5 feet) above root collar and its diameter is 30.6 inches.
Divide 30.6 by .96 and record DBH as 31.9 inches.
2. Example 2:
A dead Alaska yellow cedar tree has no bark at DBH (4.5 feet) above root collar and its diameter
is 8.7 inches. Divide 8.7 by .95 and record DBH as 9.2 inches.
See 14.12m – Exhibit 01 for a table that converts DBH to stump diameter.
14.12n – Young Growth Trees without Bark
For trees without bark, use the following bark thickness ratios to calculate Diameter at Breast
Height (DBH)
Species
Spruce
Hemlock
Bark Thickness Ratio
.97
.96
Example- A young growth tree has no bark at DBH and its diameter is 14.4 inches. Divide 14.4
by .96 and record DBH as 15.0 inches.
R-10 SUPPLEMENT 2409.12-2016-1
EFFECTIVE DATE: 4/1/2016
DURATION: Effective until superseded or removed
2409.12_10
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FSH 2409.12 – TIMBER CRUISING HANDBOOK
CHAPTER 10 – PRINCIPLES OF MEASURING TREES
14.2 – Measuring Tree Heights
Use total tree height when measuring tree heights. Measurement will be taken from one-foot
stump height on the high ground side to the tip of the tree leader, for trees with broken tops
cruise to merchantable height. Measure from one-foot stump height on the high ground side to
the break and take a top diameter inside bark at this point with a Relaskop (see example 1). If the
top diameter at the break is less than 6”, measure the merchantable height at a point where 6” is
attained and record total tree heights to the nearest foot. Record in the notes “cruised to
merchantable height.”
Example 1:
Calculate the number of logs and cruise/defect accordingly. Do not use table #4 from the Coastal
Alaska Field Guide for Old Growth Cruising to calculate the number of logs (see example 2).
R-10 SUPPLEMENT 2409.12-2016-1
EFFECTIVE DATE: 4/1/2016
DURATION: Effective until superseded or removed
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FSH 2409.12 – TIMBER CRUISING HANDBOOK
CHAPTER 10 – PRINCIPLES OF MEASURING TREES
Example 2: Merchantable height is 58’ with 12” Top DIB = first log 32’ + second log 26’ = 1.5
logs. The second log will have to be manually entered into FSCruiser. Even though the Log Data
screen shows zero for tree height and .5 logs it will calculate the volume to 58’. Deduct only for
seen defect, do not defect beyond 58’.
A live tree with a broken top with a merchantable log in the top portion that is lying on the
ground, measure the actual height and cruise/defect accordingly (see example 3).
Example 3:
1. Measure height of the stub (A).
2. Measure length of the piece on the ground (B).
3. Add the two measurements to obtain the total height, A+B=Total ht.
R-10 SUPPLEMENT 2409.12-2016-1
EFFECTIVE DATE: 4/1/2016
DURATION: Effective until superseded or removed
2409.12_10
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FSH 2409.12 – TIMBER CRUISING HANDBOOK
CHAPTER 10 – PRINCIPLES OF MEASURING TREES
14.12m – Exhibit 01 Old Growth Table
Stump Diameters outside bark at 1.0 feet above root collar given DBH
DBH
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Stump Diameters (ob) at 1.0 feet above root collar
Hemlock
Alaska Yellow Cedar
Western Red Cedar
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Dark line indicates extent of collected data