ASTM D5536-94(2004)
(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
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.
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 2004)
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.Anumber 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 .
Because wood is a biological material, its mechanical properties are subject to considerable natural
variation.Thus,theresultsofteststoevaluatethemechanicalpropertiesofaspeciesdependtoagreat
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
suchasoutlinedinPracticeE105mustbeused.However,trueprobabilitysamplingoftheforesttrees
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 D2555 Practice for Establishing Clear Wood Strength Val-
choice of procedure will depend upon the intended use for the ues
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 A third procedure, double sampling, is included prima-
rily by reference. This procedure applies the results of cruci- ing small clear wood specimens which, when tested in accor-
dance with Methods and, in conjunction with full-size product
form or random samples through correlation to improve or
update property values. tests, will provide mechanical properties for use in deriving
design properties for lumbar, panels, poles, house logs, and
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the other products.
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-
bility of regulatory limitations prior to use. influence on mechanical properties of such factors as density,
locality of growth, position in cross section, height in the tree,
and moisture content.
This practice is under the jurisdiction ofASTM Committee D07 on Wood and
3.3 Cruciformsamplingisofprincipalvaluewheninforma-
is the direct responsibility of Subcommittee D07.08 on Forests.
tion is desired on the influence on mechanical properties of
Current edition approved April 1, 2004. Published July 2004. Originally
approved in 1994. Last previous edition approved in 1999 as D5536–94 (1999).
DOI: 10.1520/D5536-94R04.
2 4
Bendtsen, B.A.; Freese, Frank; Ethington, R. L., “AForest 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 (2004)
height in the tree; of age or radial position in the tree; of rate 5.1.1 The 2 by 2-in. (50 by 50-mm) test specimen has the
of growth; the change from sapwood to heartwood; the advantage that it embraces a number of growth rings, is less
relationships between mechanical properties and factors such influencedbyearlywoodandlatewooddifferencesthansmaller
as specific gravity; and making general comparisons between specimens, and is large enough to represent a considerable
species for purposes of rating or selecting species for specific proportion of the material.
end-use products. Cruciform sampling does not provide unbi-
5.1.2 The choice of specimen size may be influenced by the
ased estimates of mean values, percentile or other descriptive
objectives of sampling and by the rate of growth of the
statistics, or a means of associating statistical confidence with material. Radial property gradients are primarily influenced by
estimates of descriptive statistics.
age, and large specimens that encompass several rings may
3.4 Double sampling is used when it is desired to improve mask the age influence. Height gradients must be evaluated by
orupdateexistingestimatesofmechanicalpropertyvaluesthat
specimensfromthesameannualringbecauseofageinfluence.
are the basis for establishing allowable design stresses for Thus, small specimens are preferred for measuring both radial
stress-graded lumber, plywood, poles and piling, and other
and height gradients. When the purpose of sampling is to
wood products. The method involves predicting one property estimate clear wood properties, large specimens that include a
bycarefullyobservingawell-correlatedauxiliarypropertythat
number of annual rings are preferred. Even with 2 by 2-in. (50
is presumably easier or cheaper to measure.Asample estimate
by 50-mm) specimens, fast rates of growth will result in few
of the auxiliary property is obtained with a high degree of
ringsperspecimen.Regardlessofthepurposeofsampling,the
precision by representatively sampling the population. A
analysis and reporting of data may require careful consider-
smallerindependentsampleorasubsampleofthelargesample
ation of the character of the specimen.
is used to establish a relationship between the auxiliary
5.2 Selection of Number of Trees—For each species to be
property and the property for which an estimate is desired.As
tested, select the number and the character of the trees to
applied to sampling a forest, double sampling has employed
accomplish the purpose of the sampling. For traditional me-
specific gravity to predict mechanical properties. The double-
chanical property data base development, a minimum of five
sampling method provides unbiased estimates of mean me-
trees have usually been selected that have been judged “rep-
chanical property values and an approximation method for
resentative” of the trees harvested of the species. Note that if
estimating percentile values. Statistical confidence may be
unbiased estimates and statistical confidence statements are
associated with the estimates of the means but not the
required, other methods are needed (Section 3).
percentile values.
5.3 Selection and Number of Bolts— The material of each
3.5 Random sampling is used when probability estimates of
species selected for test shall be representative of the clear,
descriptive statistics and property distributional characteristics
straight-grained wood in the merchantable bole of the tree. A
are desired as the basis for establishing allowable design
traditional method of selection is shown inAppendix X2. Note
stresses for lumber and other stress-rated products. It is
that the sampling permits varying the intensity of sampling by
applicablewhendataforaspeciesdonotexistorwhenexisting
tree (in accordance with A2) if the resulting data will support
estimates are believed no longer applicable because of a
the anticipated analysis. X2.1 illustrates merchantable section
changing forest character. Random sampling provides better
and bolt labeling.
probability estimates than double sampling and is less expen-
5.4 Substitution of Flitches for Bolts:
sive and quicker if sampling and testing must be completed to
5.4.1 Incaseswherethelogsorboltsareover60in.(1.5m)
establish mechanical property-specific gravity regressions for
in diameter, a single flitch 6 in. (150 mm) in thickness, taken
the double-sampling method.
through the pith representing the full diameter of the log, may
be substituted, in the same length, for the full log or bolt
4. Authentic Identification
specified in 5.3.
4.1 Thematerialshallbefromtreesselectedintheforestby
5.4.2 Where orientation of test specimen to geographic
one qualified to identify the species and to select the trees.
features is considered critical, flitch shall maintain the coordi-
Where necessary, herbarium samples such as leaves, fruit,
nates regarded as important in the specimen of 5.9.
twigs, and bark shall be obtained to ensure positive identifica-
5.5 Selection for Site Representation— Inferences in analy-
tion.
sisthatrelatetogeographicdistributionorsite-specificfeatures
must be anticipated in selecting both the sample numbers and
5. Cruciform Sampling—Primary Method
sources. The number of trees shall conform to 5.2 and 5.3.If
5.1 The standard methods for preparing small clear speci-
the analysis requires statistical inferences, random sampling
mens of timber, primary method, provide for cutting the log
(Section 7) is one method.
sections (divided into and identified as bolts) systematically
1 1 5.6 Field Marking:
into sticks of nominal 2 ⁄2 by 2 ⁄2 in. (63 by 63 mm) in cross
5.6.1 Fieldmarkingproceduresshallensureidentificationof
section, that are later surfaced to provide the test specimens 2
trees, bolts, and shipment.Appendix X2 provides a traditional
by 2 in. (50 by 50 mm) in cross section, on which the system
method.
is based. These methods have served as a basis for the
5.6.2 If the orientation of test specimens to geographical or
evaluation of the various mechanical and related physical
bolt features is critical, maintenance of cardinal point orienta-
propertiesoftheclearwoodofdifferentspeciesofwood.These
tion is recommended.
methods have been extensively used, and a large amount of
data based on them have been obtained and published. 5.7 Field Descriptions:
D5536 – 94 (2004)
5.7.1 Complete field notes describing the material shall be and care of material, is identical with the primary method, the
fully and carefully made by the collector. These notes shall be secondary method presented herewith are referenced to the
sufficient to supply documentation similar to that in Table primary method, and procedure is given only where it differs
X1.1, with actual content chosen as appropriate for the therefrom.Forconveniencethesectionnumbersinthesecond-
objectives of the study. ary method corresponds in the last two digits with the
5.7.2 Photographs of the standing trees selected should be numbering of the primary method. Thus Section 6 for the
taken when practicable. secondary method corresponds in subject matter to Section 5.
5.8 Preparation for Shipment—Maintenance of moisture 6.1.1 Because of the cross-sectional size and the length of
content of the material and of all labeling documentation is a
specimen required for some of the tests (30 in. (760 mm) for
requirement. Paragraph X2.3 provides traditional guidelines. staticandimpactbending)itis,however,sometimesdifficultto
5.9 Sawing and Marking of Bolts and Test Sticks—Sections
obtain test specimens in adequate number and entirely free of
oflogs(consistingoftwobolts)shallbemarkedandsawninto defects from bolts representing smaller trees, particularly trees
1 1
2 ⁄2 by 2 ⁄2-in. (60 by 60-mm) sticks. Marking of bolts and
under 12 to 15 in. (30 to 38 cm) in diameter. With increasing
sticks shall maintain continuity to the tree, and shipment. need for evaluating the properties of species involving smaller
Consistency with 5.6 shall be maintained. Paragraphs A2.1
trees, and the increasing importance of second-growth timber
through A2.4 document the traditional procedures.
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
thatarecloselymatchedbyselectionfromadjacentpartsofthe
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 5.9.1, 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-ftstickshallthenbecutintotwo4-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
6.2 Selection and Number of Trees— For each species to be
specimens to be tested green (unseasoned) and the remaining
tested, at least ten trees representative of the species shall be
ones are to be dried and tested. To afford matching, the 4-ft
selected.
sticks of one bolt shall be interchanged with the 4-ft sticks of
6.3 Selection and Number of Bolts:
the next adjacent bolt from the same tree to form two
6.3.1 See 5.3.1, noting that, if using A2.1.1 as a guide, the
composite bolts, each being complete and being made of equal
minimum number of trees is increased to 10. If information on
portionsoftheadjacent4-ftbolts.Thesticksfromoneofthese
variation with height is desired, us
...
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