ASTM D5536-94(2010)
(Practice)Standard Practice for Sampling Forest Trees for Determination of Clear Wood Properties
Standard Practice for Sampling Forest Trees for Determination of Clear Wood Properties
SIGNIFICANCE AND USE
This practice covers procedures of sampling for obtaining small clear wood specimens which, when tested in accordance with Methods D143 and, in conjunction with full-size product tests, will provide mechanical properties for use in deriving design properties for lumber, panels, poles, house logs, and other products.
Data obtained by testing specimens sampled in accordance with these methods also provide information on the influence on mechanical properties of such factors as density, locality of growth, position in cross section, height in the tree, and moisture content.
Cruciform sampling is of principal value when information is desired on the influence on mechanical properties of height in the tree; of age or radial position in the tree; of rate of growth; the change from sapwood to heartwood; the relationships between mechanical properties and factors such as specific gravity; and making general comparisons between species for purposes of rating or selecting species for specific end-use products. Cruciform sampling does not provide unbiased estimates of mean values, percentile or other descriptive statistics, or a means of associating statistical confidence with estimates of descriptive statistics.
Double sampling is used when it is desired to improve or update existing estimates of mechanical property values that are the basis for establishing allowable design stresses for stress-graded lumber, plywood, poles and piling, and other wood products. The method involves predicting one property by carefully observing a well-correlated auxiliary property that is presumably easier or cheaper to measure. A sample estimate of the auxiliary property is obtained with a high degree of precision by representatively sampling the population. A smaller independent sample or a subsample of the large sample is used to establish a relationship between the auxiliary property and the property for which an estimate is desired. As applied to sampling a forest, double sampling ha...
SCOPE
1.1 This practice offers two alternative physical sampling procedures: cruciform sampling and random sampling. The choice of procedure will depend upon the intended use for the test results, the resources available for sampling and testing, and the availability of existing data on the mechanical properties and specific gravity of the species of interest.
1.2 A third procedure, double sampling, is included primarily by reference. This procedure applies the results of cruciform or random samples through correlation to improve or update property values.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D5536 − 94(Reapproved 2010)
Standard Practice for
Sampling Forest Trees for Determination of Clear Wood
Properties
This standard is issued under the fixed designation D5536; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The everyday use of wood for many different purposes creates a continual need for data on its
mechanical properties. Small clear specimen testing to characterize a species has historically been
employed for such property determination, and related methods of test are outlined in Methods D143.
Because wood is a biological material, its mechanical properties are subject to considerable natural
variation.Thus, the results of tests to evaluate the mechanical properties of a species depend to a great
extent upon how the forest trees are sampled for test material. Ideally, if the results of mechanical
property evaluations are to be representative of the forest sampled, probability sampling of materials
such as outlined in Practice E105 must be used. However, true probability sampling of the forest trees
for determination of mechanical properties can be extremely complex and expensive because of the
broad geographic range and topographic conditions under which a tree species grows. In some
instances, direct probability sampling may be impractical, necessitating the need for alternative
2, 3
sampling procedures.
1. Scope 2. Referenced Documents
1.1 This practice offers two alternative physical sampling 2.1 ASTM Standards:
procedures: cruciform sampling and random sampling. The D143 Test Methods for Small Clear Specimens of Timber
choice of procedure will depend upon the intended use for the D2555 PracticeforEstablishingClearWoodStrengthValues
test results, the resources available for sampling and testing, E105 Practice for Probability Sampling of Materials
and the availability of existing data on the mechanical proper-
3. Significance and Use
ties and specific gravity of the species of interest.
3.1 This practice covers procedures of sampling for obtain-
1.2 Athird procedure, double sampling, is included primar-
ing small clear wood specimens which, when tested in accor-
ilybyreference.Thisprocedureappliestheresultsofcruciform
dance with Methods D143 and, in conjunction with full-size
or random samples through correlation to improve or update
product tests, will provide mechanical properties for use in
property values.
deriving design properties for lumber, panels, poles, house
1.3 This standard does not purport to address all of the
logs, and other products.
safety concerns, if any, associated with its use. It is the
3.2 Data obtained by testing specimens sampled in accor-
responsibility of the user of this standard to establish appro-
dance with these methods also provide information on the
priate safety and health practices and determine the applica-
influence on mechanical properties of such factors as density,
bility of regulatory limitations prior to use.
locality of growth, position in cross section, height in the tree,
and moisture content.
This practice is under the jurisdiction of ASTM Committee D07 on Wood and
3.3 Cruciform sampling is of principal value when informa-
is the direct responsibility of Subcommittee D07.08 on Forests.
CurrenteditionapprovedMay1,2010.PublishedJuly2010.Originallyapproved tion is desired on the influence on mechanical properties of
in 1994. Last previous edition approved in 2004 as D5536 – 94 (2004). DOI:
10.1520/D5536-94R10.
2 4
Bendtsen, B. A., Freese, F., and Ethington, R. L., “A Forest Sampling Method For referenced ASTM standards, visit the ASTM website, www.astm.org, or
for Wood Strength,” Forest Products Journal, Vol 20, No. 11, 1970, pp. 38–47. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Pearson, R. G., and Williams, E. J., “A Review of Methods for Sampling of
Standards volume information, refer to the standard’s Document Summary page on
Timber,” Forest Products Journal, Vol 8, No. 9, 1958, pp. 263–268.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5536 − 94 (2010)
height in the tree; of age or radial position in the tree; of rate methods have been extensively used, and a large amount of
of growth; the change from sapwood to heartwood; the data based on them have been obtained and published.
relationships between mechanical properties and factors such
5.1.1 The 2 by 2-in. (50 by 50-mm) test specimen has the
as specific gravity; and making general comparisons between
advantage that it embraces a number of growth rings, is less
species for purposes of rating or selecting species for specific
influenced by earlywood and latewood differences than smaller
end-use products. Cruciform sampling does not provide unbi-
specimens, and is large enough to represent a considerable
ased estimates of mean values, percentile or other descriptive
proportion of the material.
statistics, or a means of associating statistical confidence with
5.1.2 The choice of specimen size may be influenced by the
estimates of descriptive statistics.
objectives of sampling and by the rate of growth of the
material. Radial property gradients are primarily influenced by
3.4 Double sampling is used when it is desired to improve
age, and large specimens that encompass several rings may
or update existing estimates of mechanical property values that
mask the age influence. Height gradients must be evaluated by
are the basis for establishing allowable design stresses for
specimens from the same annual ring because of age influence.
stress-graded lumber, plywood, poles and piling, and other
Thus, small specimens are preferred for measuring both radial
wood products. The method involves predicting one property
and height gradients. When the purpose of sampling is to
by carefully observing a well-correlated auxiliary property that
estimate clear wood properties, large specimens that include a
is presumably easier or cheaper to measure.Asample estimate
number of annual rings are preferred. Even with 2 by 2-in. (50
of the auxiliary property is obtained with a high degree of
by 50-mm) specimens, fast rates of growth will result in few
precision by representatively sampling the population. A
rings per specimen. Regardless of the purpose of sampling, the
smaller independent sample or a subsample of the large sample
analysis and reporting of data may require careful consider-
is used to establish a relationship between the auxiliary
ation of the character of the specimen.
property and the property for which an estimate is desired. As
applied to sampling a forest, double sampling has employed
5.2 Selection of Number of Trees—For each species to be
specific gravity to predict mechanical properties. The double-
tested, select the number and the character of the trees to
sampling method provides unbiased estimates of mean me-
accomplish the purpose of the sampling. For traditional me-
chanical property values and an approximation method for
chanical property data base development, a minimum of five
estimating percentile values. Statistical confidence may be
trees have usually been selected that have been judged “rep-
associated with the estimates of the means but not the
resentative” of the trees harvested of the species. Note that if
percentile values.
unbiased estimates and statistical confidence statements are
required, other methods are needed (Section 3).
3.5 Random sampling is used when probability estimates of
descriptive statistics and property distributional characteristics
5.3 Selection and Number of Bolts—The material of each
are desired as the basis for establishing allowable design
species selected for test shall be representative of the clear,
stresses for lumber and other stress-rated products. It is
straight-grained wood in the merchantable bole of the tree. A
applicablewhendataforaspeciesdonotexistorwhenexisting
traditional method of selection is shown in Appendix X2. Note
estimates are believed no longer applicable because of a
that the sampling permits varying the intensity of sampling by
changing forest character. Random sampling provides better
tree (in accordance with A2) if the resulting data will support
probability estimates than double sampling and is less expen-
the anticipated analysis. X2.1 illustrates merchantable section
sive and quicker if sampling and testing must be completed to
and bolt labeling.
establish mechanical property-specific gravity regressions for
5.4 Substitution of Flitches for Bolts:
the double-sampling method.
5.4.1 In cases where the logs or bolts are over 60 in. (1.5 m)
in diameter, a single flitch 6 in. (150 mm) in thickness, taken
4. Authentic Identification
through the pith representing the full diameter of the log, may
4.1 The material shall be from trees selected in the forest by
be substituted, in the same length, for the full log or bolt
one qualified to identify the species and to select the trees.
specified in 5.3.
Where necessary, herbarium samples such as leaves, fruit,
5.4.2 Where orientation of test specimen to geographic
twigs, and bark shall be obtained to ensure positive identifica-
features is considered critical, flitch shall maintain the coordi-
tion.
nates regarded as important in the specimen of 5.9.
5.5 SelectionforSiteRepresentation—Inferencesinanalysis
5. Cruciform Sampling—Primary Method
that relate to geographic distribution or site-specific features
5.1 The standard methods for preparing small clear speci-
must be anticipated in selecting both the sample numbers and
mens of timber, primary method, provide for cutting the log
sources. The number of trees shall conform to 5.2 and 5.3.If
sections (divided into and identified as bolts) systematically
the analysis requires statistical inferences, random sampling
1 1
into sticks of nominal 2 ⁄2 by 2 ⁄2 in. (63 by 63 mm) in cross
(Section 7) is one method.
section, that are later surfaced to provide the test specimens 2
5.6 Field Marking:
by 2 in. (50 by 50 mm) in cross section, on which the system
is based. These methods have served as a basis for the 5.6.1 Fieldmarkingproceduresshallensureidentificationof
evaluation of the various mechanical and related physical trees, bolts, and shipment. Appendix X2 provides a traditional
propertiesoftheclearwoodofdifferentspeciesofwood.These method.
D5536 − 94 (2010)
5.6.2 If the orientation of test specimens to geographical or trees because of crook, cross grain, knots, or other defects are
bolt features is critical, maintenance of cardinal point orienta- ofsuchqualitythatthelongerclear,straight-grainedspecimens
tion is recommended. requiredbytheprimarymethodcannotreasonablybeobtained.
Whenever possible, the procedure for the primary method shall
5.7 Field Descriptions:
be used regardless of the size of trees. Since the procedure for
5.7.1 Complete field notes describing the material shall be
the secondary method for many features, such as in selection
fully and carefully made by the collector. These notes shall be
and care of material, is identical with the primary method, the
sufficient to supply documentation similar to that in Table
secondary method presented herewith are referenced to the
X1.1, with actual content chosen as appropriate for the
primary method, and procedure is given only where it differs
objectives of the study.
therefrom. For convenience the section numbers in the second-
5.7.2 Photographs of the standing trees selected should be
ary method corresponds in the last two digits with the
taken when practicable.
numbering of the primary method. Thus, Section 6 for the
5.8 Preparation for Shipment—Maintenance of moisture
secondary method corresponds in subject matter to Section 5.
content of the material and of all labeling documentation is a
6.1.1 Because of the cross-sectional size and the length of
requirement. Paragraph X2.3 provides traditional guidelines.
specimen required for some of the tests (30 in. (760 mm) for
5.9 Sawing and Marking of Bolts and Test Sticks—Sections staticandimpactbending)itis,however,sometimesdifficultto
of logs (consisting of two bolts) shall be marked and sawn into obtain test specimens in adequate number and entirely free of
1 1
2 ⁄2 by 2 ⁄2-in. (60 by 60-mm) sticks. Marking of bolts and defects from bolts representing smaller trees, particularly trees
sticks shall maintain continuity to the tree, and shipment. under 12 to 15 in. (30 to 38 cm) in diameter. With increasing
Consistency with 5.6 shall be maintained. Paragraphs A2.1 need for evaluating the properties of species involving smaller
through A2.4 document the traditional procedures. trees, and the increasing importance of second-growth timber
thatisexpectedtobeharvestedmuchbeforeitreachesthesizes
5.10 Matching for Tests of Dry Material:
attained in virgin stands, there has developed a need for
5.10.1 If one purpose of sampling is to provide comparison
secondary methods of test in which at least the longer test
of green and dry properties, provisions may be made for
specimens are smaller than 2 by 2 in. (50 by 50 mm) in cross
matching of specimens within the tree. The traditional ap-
section.
proach is as follows:
6.1.2 The exceedingly rapid rate of growth and correspond-
5.10.2 The collection of the material (Section 5) has been
ing wide annual rings in much second-growth material, to-
arranged to provide for tests of both green and dry specimens
gether with the desirability of incorporating more than a single
that are closely matched by selection from adjacent parts of the
year’s growth increment in a test specimen, has necessitated
sametree.The8-ft(2.4-m)longsections,afterbeingmarkedin
limiting the minimum cross section of test piece in these
accordance with 5.9, shall be sawn and marked in 2 ⁄2 by
secondary methods to 1 by 1 in. (25 by 25 mm). Data analysis
1 1 1
2 ⁄2-in. (60 by 60-mm) by 8-ft sticks. Each 2 ⁄2 by 2 ⁄2-in. by
based on these small specimens of rapid growth rate wood is
8-ft stick shall then be cut into two 4-ft (1.2-m) pieces, making
particularly vulnerable if the purpose of the sampling is to
surethateachpartcarriestheproperdesignationandboltletter.
estimate total clearwood properties. See additional comments
1 1
5.10.3 Some of the 2 ⁄2 by 2 ⁄2-in. by 4-ft (60 by 60-mm by
in 5.1.2.
1.2-m) sticks from each 8-ft (2.4-m) section are to provide
specimens to be tested green (unseasoned) and the remaining
6.2 Selection and Number of Trees—For each species to be
ones are to be dr
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