A Key for the ForestService
Hardwood
Tree Grades
tions involve three major characteristicsof the gradingsection:
(1) size--diameter breast height
(dbh) and diameter inside bark
(dib) at the top of the gradingsection,
Gary W. Miller, USDA ForestService,Timberand
Watershed
Laboratory,
P.O. Box404, Parsons,WV 26287;
Leland F. Hanks, USDA ForestService,310 W. Wisconsin
Avenue,Milwaukee,WI 53203;andHarry V. Wiant, Jr.,
DivisionofForestry,WestVirginiaUniversity,
Morgantown,WV 26506.
(2) clearcuttings--thetotal lengthof
allowable clear cuttings on the
secondworst face of the grading
section, and
(3) cull deductions--the percentage
of volumedeductedfor sweepand
crook and the percentage of
volume deducted for sweep,
crook, and rot combined.
As a tree is graded, each of these
characteristics
ABSTRACT. A dichotomous
key or-
key addresses
the gradefactorsin a
ganizesthe USDA ForestServicehard-
sequencethat reduces confusionand
improves comprehension.Third, the
woodtreegradespecifications
intoa step-
wiseprocedure
for those
learning
tograde keycanbe usedto learnhow to grade
hardwood
sawtimber.
Thekeyaddresses hardwood trees without detailed inthemajorgradefactors,
treesize,surface struction. Field trials have indicated
characteristics,and allowablecull deducthat beginnerscan use the key to detionsin a series
of pairedchoices
thatlead termine the correcttree grade, while
theusertoa decision
regarding
treegrade. those using other referencesrequire
Subtle
gradingrules,previously
presented outsidehelp. This featureof the key
asfootnotes
tothemajorspecifications,
are
allowsthebeginnerto becomecompeincludedin the key. It simplifiesthe
tent without the delaysand costsasprocess
sothatthebeginner
canlearnthe
sociatedwith moreformaltraining.As
systemquickly,withoutdetailedinstruca result, tree gradescan be used to
tionfromexperienced
treetraders.
assess tree quality and value in a
North.J. Appl.For.3:19-22,Mar. 1986.
shorterperiodof time.
USDAForest
Service
hardwood
tree
BACKGROUND
gradesare used to predict factory
lumbergradeyieldsfor many com-
The most difficult part of tree
grading is recognizing defect indi-
mercialhardwoodtreespecies(Hanks
1976, Hanks and Brisbin1978). The
gradingsystemmakesit possibleto
cators on the surface of the tree. Pho-
timberfrom the gradesand pricesof
Lockardet al. 1963). Estimatingin-
tographic guides are available for
somecommercialspecies(Rast 1982,
calculate
the dollarvalueof standing Shigo1983,Marden and Stayton1970,
lumber that can be sawn from individual trees. Once familiar with the
system,timbergraderscan provide
consistentestimatesof timberquality
andstandvalue.Thekeypresented
in
thispaperservesas a teachingaid for
those learning to grade hardwood
trees. It providesa stepwiseprocedurefor determining
the gradesof individualtreesandorganizes
thegrade
specifications
so that the beginner
is not overwhelmed
with
choices
terior cull deductions
is also difficult
for the beginner.References
are available for making adjustments for
sweep,crook,and rot (Rastet al. 1973,
Petro 1971, USDA
Forest Service
1973). In addition to learning the
grade specifications, the trainee
should
use and review
these refer-
encesto maintain competencein all
aspectsof gradingand scaling.
TREE GRADE
SPECIFICATIONS
(Table1).
Many peoplefind it difficultto learn
Tree grade is generallydetermined
by characteristicsof the best 12-ft
thetreegradingsystemusingexisting gradingsectionin the butt 16-ftlog. A
references,especiallywhen experi- 14- or 16-ft grading sectionmay be
encedgradersarenotavailableto pro- usedif it resultsin a bettergradethan
vide detailedinstruction.The key the 12-ftsection.Fieldexperience
with
overcomesthree major problemsbeForestServicetree gradeshas shown
ginnersoftenencounter
when trying that tree grade is usually definedby
to learntreegradingfromearlierpre-
characteristics of the bottom 12-ft sec-
sentations.First, the key containsthe
tion or the top 12-ft sectionin the butt
subtlegradespecifications
previously log. Occasionally,however,usinga
presentedas footnotesto the major 14- or 16-ft gradingsectionresultsin a
grade factors. This improvement highergrade.A simplerule is to use
makesthe beginnerawareof the fine
the gradingsectionthat resultsin the
pointswithoutdisrupting
thesteep-by- highesttree grade.
step processof grading.Second,the
Forest Servicetree grade specifica-
is examined
to deter-
mine whether the tree qualifiesfor a
particulargrade. The key addresses
each characteristicin a logical, stepwiseprocedure.In effect,the key systematically tests each characteristic
until the tree is graded.
Size
Both dbh and dib at the top of the
grading sectionmust satisfythe minimum requirements of the assigned
tree grade(Hanks1976).The first step
in determining tree grade is to
measure
dbh to the nearest inch. For
grades1, 2, and 3 the minimum dbh
requirementsare 16, 13, and 10 in, re-
spectively. Dib at the top of the
grading section,however, is the more
important specification for determininggrade.This is becausedib and
another major tree grade character-
istic, clear cuttings,are interrelated.
Dib at the top of the gradingsection
definesthe minimum length or the
maximumnumberof clearcuttingsallowedin grades1 and 2.
Sincedib at the top of the grading
sectioncannotbe measureddirectly,it
must be estimated
from dbh and an
assignedform class.Recall that the
top of the gradingsectioncan be 12,
14, or 16 ft abovestumpheight. For a
givendbh, dibwill differat 12, 14, and
16 ft above stump height becauseof
taper. Tables2 and 3 show the minimum dbh required to meet the dib
limitations
for Girard
form classes 79
and 82, respectively.
To use the tables,locatethe appropriate dib limitation in the column of
numbersat the left. Then find the po-
sitionof the gradingsectionacrossthe
top of the table.The numbershownin
the tableis the minimumdbhrequired
to meet the dib limitationat that position. For example,the key indicatesa
minimum
dib of 12.6 in for a tree that
measures15.8 in dbh. The top of the
gradingsectionis at 16 ft abovestump
heightand form classis 79. Is the tree
at least 12.6 in in dib at 16 ft above
stumpheight?From Table2, a tree of
form class 79 must be at least 16.0 in
dbh to have an inside bark diameter of
12.6 in at 16 ft above stump height.
NJAF3(1986) 19
Table1. Keyfor hardwoodtree gradesbasedon the secondworstfaceof the best12-footsectionof
the butt 16-ft log.
1. Minimum dbh of 15.6 inches (14.6 inches for basswood and ash) ............................................................................................
1. Minimum dbh of 12.6 inches ............................................................................................................................................
2
10
1. Minimumdbh of 9.6 inches(If dbh is lessthan 9.6 inchesstop here; tree is belowgrade).......................................................
18
2. Clearcuttingstotal at least10 feet in 1 or 2 cuttings--eachcuttingat least
7 feet long.................................................................................................................................................................
2. Clear cuttingstotal lessthan 10 feet in 1 or 2 cuttings--each cuttingat least
7 feet long.................................................................................................................................................................
2. Clear cuttingstotal lessthan 10 feet in 1 or 2 cuttings--each cuttingat least
7 feet Iong...(dueto rot only) .....................................................................................................................................
5
3
15
3. Clearcuttingstotal at least10 feet in 1 or 2 cuttings--eachcuttingat least5 feet long ..............................................................
3. Clear cuttingstotal lessthan 10 feet in 1 or 2 cuttings--each cuttingat least5 feet long............................................................
3. Clear cuttingstotal lessthan 10 feet in 1 or 2 cuttings--each cuttingat least5 feet long...
(due to rot only).............................................................................................................................................................
4. Clearcuttingstotal at least10 feet in 1 or 2 cuttings--eachcuttingat least'3feet long ........................................................
4. Clear cuttingstotal lessthan 10 feet in 1 or 2 cuttings--each cuttingat least3 feet long ....................................................
4. Clearcuttingstotal lessthan 10 feet in 1 or 2 cuttings--eachcuttingat least3 feet long...
(due to rot only) .......................................................................................................................................................
6
4
15
7
11
15
5. Dib at top of gradingsectionat least12.6 inches(11.6 inchesfor basswoodand ash) ................................................................
5. Dib at top of gradingsectionlessthan 12.6 inches(11.6 inchesfor basswoodand ash)............................................................
8
17
6. Dib at top of gradingsectionat least15.6 inches............................................................................................................
6. Dib at top of grading section lessthan 15.6 inches........................................................................................................
8
17
7. Dib at top of gradingsectionat least19.6 inches..................................................................................................................
7. Dib at top of gradingsectionlessthan 19.6 inches..............................................................................................................
8
17
8. Totalcull deduction,includingsweep,crook, and rot does not exceed9%.............................................................
8. Total cull deduction
GRADE1
exceeds 9% ..................................................................................................................................
9
9. Cull deduction does not exceed 15% for sweep and crook, and total cull deduction does not exceed40%........................
GRADE2
9. Cull deductionfor sweepand crookexceeds15%or total cull deductionexceeds40%............................................................
20
10. Clear cuttingstotal at least10 feet in 1 or 2 cuttings--each cuttingat least7 feet long.......................................................
10. Clear cuttingstotal lessthan 10 feet in 1 or 2 cuttings--each cuttingat least7 feet long ....................................................
17
11
11. Clearcuttingstotal at least8 feet in 1 or 2 cuttings--eachcuttingat least3 feet long ..............................................................
11. Clearcuttingstotal lessthan 8 feet in 1 or 2 cuttings--eachcuttingat least3 feet long............................................................
13
12
12. Clear cuttingstotal at least8 feet in 1, 2, or 3 cuttings--each cuttingat least
3 feet long ...............................................................................................................................................................
12. Clearcuttingstotal lessthan 8 feet in 1,2, or 3 cuttings--eachcuttingat least
3 feet long ...............................................................................................................................................................
14
18
13. Dib at top of gradingsectionat least10.6 inches.................................................................................................................
13. Dib at top of gradingsectionlessthan 10.6 inches..............................................................................................................
17
20
14. Dib at top of gradingsectionat least11.6 inches...........................................................................................................
14. Dib at top of gradingsectionlessthan 11.6 inches........................................................................................................
15. Clear cuttingstotal at least8 feet in 1, 2, or 3 cuttings--each cuttingat least3 feet long..........................................................
15. Clear cuttingstotal lessthan 8 feet in 1,2, or 3 cuttings--each cuttingat least3 feet long........................................................
16. Cull deduction for rot does not exceed 40% .......................................................................................................
16. Cull deduction for rot exceeds 40% .............................................................................................................................
16
18
GRADE 2
20
17. Total cull deduction, includingsweep, crook, and rot does not exceed9%...................................................................
17. Total cull deduction
17
20
exceeds 9% .......................................................................................................................................
GRADE2
20
18.
18.
Clear cuttingstotal at least6 feet, all cuttingsat least2 feet long.....................................................................................
19
Clearcuttingstotal lessthan 6 feet, all cuttingsat least2 feet long................................................................
BELOWGRADE
19. Dib
19. Dib
at top of gradingsectionat least7.6 inches..................................................................................................................
20
at top of gradingsectionlessthan 7.6 inches.............................................................................................
BELOWGRADE
20. Total cull deduction,includingsweep,crook, and rot does not exceed50% ...........................................................
GRADE3
20. Total cull deduction exceeds 50% .............................................................................................................
BELOW GRADE
Dib at the top of the gradingsectionis
less than 12.6 in because the dbh of
this particulartree is only 15.8in.
ClearCuttings
To determine the total length of
clear cuttings on the grading section,
20
NJAF3(1986)
the first stepis to identifythe grading
face of the tree. Visually squarethe
butt log into four faces,using imaginary verticallines. Arrange the faces
and the next-to-worst
face becomes
so that most defect indicators, such as
extends
bumpsand knots,are concentratedon
one face. The worst face is ignored,
grade specifications
define the minimum length of clear cuttings, the
the gradingfaceof the tree.
A clear cuttingis a portion of the
gradingfacethatis freeof defectsand
the width
of the face. The
Table 2. Minimum dbh (in inches) re-
Table 3. Minimum dbh (in inches) re-
Table 4. Minimum total length (in
quiredto meet dib limitationsmtrees
quired to meet dib limitations--trees
with form class 79.
with form class 82.
feet and inches)of clear cuttingsrequired for each grade and length of
gradingsection.
Length
Minimum
totallengthof
Positionof gradingsection,feet
abovestumpheight
Positionof grad!ngsection,feet
above•stumpheight
Dib
0-12
19.6
15.6
12.6
11.6
10.6
9.6
7.6
23.0
18.3
14.8
13.6
12.4
11.3
8.9
2-14
4-16
23.9
19.0
15.4
14.2
12.9
11.7
9.3
Dib
24.9
19.8
16.0
14.7
13.5
12.2
9.6
19.6
15.6
12.6
11.6
10.6
9.6
7.6
0-12
2-14
22.4
17.9
14.4
13.3
12.1
11.0
8.7
23.2
18.4
14.9
13.7
12.5
11.4
9.0
4-16
24.0
19.1
15.4
14.2
13.0
11.7
9.3
of
clearcuttings
a
grading
section
Grade 1
Grade 2
Grade 3
10'
11 '8"
13'4"
8'
9'4"
10'8"
6'
7'
8'
12'
14'
16'
ßClear cuttingsmusttotal 5/6, 4/6, and 3/6 of the
lengthof the gradingsectionfor grades1,2, and
3, respectively.
maximum number of cuttings allowed, and the minimum total length
of clear cuttingsfor each.tree grade
Clear cuttingsmust total 5/6, 4/6, and
3/6of the lengthof the gradingfacefor
grades1, 2, and 3, respectively.The
key assumesa 12-ftgradingsection.If
a longer grading sectionis used, the
minimumtotallengthof clearcuttings
statedin the key shouldbe adjusted
accordingto Table4.
•6'
Defect section (rule 1):
Percent
deduction
= I-•: 25%
Cull Deductions
I,
The key also defines maximum allowabledeductionsfor sweep,crook,
and rot. Figure 1 shows how most
scalingdeductionsare determined.In
calculatingpercentsweep deduction,
16'
Defect section(rule 2):
the number
I
'"----._
..........
-....
16'
Sweep(rule 3):
Percent
deduction 8 -- 2
subtracted
from
actual
sweep varies with log length. When
calculating percent deduction for
sweep,the numeratoris the sweep(in
inches)minusI•A in for a 12-ftgrading
section
and
2 in for
a 14- or 16-ft
gradingsection(Rastet al. 1973).Estimating internal rot requires good
judgment and a lot of practice.The
National Forest Log Scaling Handbook (USDA For. Serv. 1973)provides
detailed instructionsfor estimating
most scalingdeductions.
USING
THE KEY
Specificinstructions
on treegrading
are presented in "Hardwood tree
16'
Crook (rule 4):
lb'
Interior defect (rule 5):
Pe•e•t
deduction
• (20
(8)(10)
-- 1)' X1-•: 55/9%.
grades for factory lumber" (Hanks
1976).The key simplyorganizesall the
grade specificationsand provides a
stepwiseprocedurefor the beginner
For each tree, start at the top of the
key and proceedto the stepindicated
in the right-handcolumnof numbers
Continuefollowing the key until the
tree is graded. At first the beginner
should rely on the key and consult
Figure 1 to estimate scaling deductions.With more experience,grading
canbe donefrom memory.
[]
aI•rmpmetlce
eachelipseaxiscanbe dividedby (20-- 1)
mudded to hearst tenth if •
Tht•1'•= .4,10
•rom: Ormenhaugh,
L. R., $•owr cu• eox•
Exp. •te., Occa•Pa•er 126,1952.
LITERATURE
A•mSCAL•S,USDA Fo•t
•e•v. South.Forest
NE-333. 81 p.
HANKS, L.
Fig. 1. Methodso• determiningscalingdeduction(examples
based
ona 16-filo• with20-in
scalin•diameter).
CITED
HANKS,
L. F. 1976.Hardwoodtreegradesfor factory lumber. USDA For. Serv. Res. Pap
F., and R. L. BRISBIN.1978. Lumber
grade yields for graded aspenlogs and trees
USDA For. Serv. Res.Pap. NE-423. 13 p.
NJAF3(1986) 21
Loc•c^av, C. R., J. A. PUTNAM,and R. D. CAaPENTER. 1963.
Grade
defects
in hardwood
timber and logs. USDA For. Serv. Agric.
Handb.244.39 p.
]•La•RDEN,
R. M., and C. L. STAYTON.
1970. Defect
indicatorsin sugar-maple:a photographic
guide.USDAFor.Serv.Res.Pap.NC-37.29p.
PETRO,F. J. 1971. Felling and bucking hard-
woods:how to improveyour profits.Can.
Dep. Fish.and For., Can. For. Serv., Ottawa,
Ontario.Publ.No. 1291.140p.
RAST,
E. D. 1982.Photographic
guideof selected
external defect indicators and associated internal defects in northern red oak. USDA For.
Serv.Res.Pap.NE-511.20p.
RAST, E. D.,
D. L. SONDERMAN, and G. L.
Adjusting Timberland Lease
Paymentsfor Stumpage
Price-Changes
W. David Klemperer, VirginiaPolytechnic
InstituteandState
University,Blacksburg,
VA 24061.
GAMMON.1973. A guide to hardwood log
grading.USDA For. Serv.Gen. Tech. Rep.
NE-1.32 p.
S•co, A. L. 1983.Tree defects:a photo guide.
USDA For. Serv. Gen. Tech. Rep. NE-82.
167p.
USDAFOR.SERV.
1973.Nationalforestlogscaling
handbook.Wash.,DC. 184p.
lower rate than "ordinary" income
(e.g., leaseincometo the landowner).
NOTATION
The followingnotationis used. All
valuesare on a per acrebasis,where
relevant, and percentagerates are in
decimal form. Variables are:
n = contractlengthin years(alsothe
rotationlength, if no regeneration delay occurs),
d = regenerationdelay, or yearsbetween contract-start
and first re-
forestation.Ideally, tractswith
and Tedder 1977, Meyer 1984). How-
ABSTRACT.Many pastindustrialleases
of privatetimberlands
haveprovenunsatisfactoryfor landowners,because
lease
payments
wereconstant
duringperiods
of
rapidlyincreasing
timberprices.
Although
manycontracts
nowindexleasepayments
to theinflationrate,few incorporate
real
•ncreases
in stumpage
pricesabovetheinfiation rate. Thispaperexamines
varia-
ever, little information is available on
differing regenerationdelays
shouldhave separateleasecon-
tracts,
methodsdiscussedhere for incorporating real stumpageprice-increases g = average annual real rate of
(above inflation) into paymentsfor
stumpageprice increaseabove
leasingtimberlands.Such real priceinflation,
increases
havebeensignificantfor ceranticipatedaverageannualinflatain typesof stumpagein the United
tion rate,
Statesin the past and are projectedto
gross
harvest revenue per acre
continue, although at a somewhat
in year n expressed in today's
tionsof two basicmethods
for incorpo- slowerpace(USDAFor. Serv.1982).
stumpagevalues(actualharvest
ratingrealstumpage
price-increases
into
revenuein year n is H(1 + g)"(!
formulas
for determining
acceptable
lease
+
LEASE
ASSUMPTIONS
payments
from viewsof bothlandowner
r
=
real
interest rate (desired afterandfirm. These
approaches
offermoresatThis paper discusses leases of
tax
earning
rate), equal to [(1 +
•sfactory
means
for nonindustrial
private stocked or bare land that is reforested
i)/(1 + •)1 - 1,
forestlandowners
to receive
annualincome
by the firm after harvestingany exnominalinterestrate (i = r + f
before
harvest
andforfirmstoobtainwood isting timber, clearcut one rotation
+r•),
supplies
withoutthehighcostoflandpur- later, and returned to the owner as
chase.
reforestation
cost per acre in
bareland. Any initiallyexistingtimber
North.J. Appl. For. 3:22-25, Mar. 1986.
year zero dollars,
is assumedto be purchasedunder a
annualcostsper acrein constant
separatecontract. (A recent survey in
dollarsoccurringfrom years 1
the Southindicatedthat firms usually
throughn,
liquidateexistingmerchantable
timber
Forest
products
firms
have
often
on leased lands within the first few
c
=
capital
gainstax rate (appliedto
leased timberlands
to assure future
current dollar timber harvest
yearsand then reforest[Meyer 1984].)
wood supplieswithout the high cost Initially, thinnings are omitted, and
revenue including inflation and
of land purchases.Although most
real pricegrowthminusoriginal
even-aged management is assumed.
leasinghas occurredin the South, the
reforestationcost),
Leasepaymentsare annual, and no
practice holds promise in other readditionalpaymentis due at harvest
gions(Zinn and Miller 1984).Despite date unless the contract specifies t = tax rate on ordinary income
againstwhich nonreforestation
a 30% decline in leased area since
added payment for real increasesin
costs can be deducted,
1970, southern forest management stumpageprices.It is shownhow the
P = initialannualleasepaymentper
contractsare still significant--4.7milequations derived here could be
acrebeforetaxes(maximumthe
lion acresin 1984(Siegel1973,Meyer
adaptedto other typesof leases.Alfirm
is willing to pay and min1984).
though beyond this paper's scope,
imum amount
landowner
reThe decline in leased acres is due in
other kinds of contracts are discussed
quires);
first
payment
due
impart to landownerdissatisfaction
with
in Bradley (1967), Siegeland Guttenmediately,lastpaymentdueone
earlier contracts under which lease
berg (1968), Somberg(1971), Guttenyear from contract end, for a
payments did not keep pace with
berg (1972),Ruff (1973),Siegel(1973),
totalof n payments,
rising timber values. To resolve this
Meyer (1984),Zinn and Miller (1982).
m = a factorby whichto multiplythe
problem, many new contractsin the
The firm will pay costsof annual
initialleasepaymentto compute
United Statesnow index lease paytaxes,reforestation,and management,
the firm'safter-taxpresentvalue
ments to the inflation rate (Hotvedt
which are assumed to rise at the inflaof annual lease payments,
tion rate but remain
fixed in real
• Financialsupportof this researchby the
USDA
Forest Service Southern
Forest Ex-
perimentStationis gratefullyacknowledged.
22
NJAF 3(1986)
terms.
The U.S.
income
tax structure
is applied, so that incomefrom assets
held longer than 6 months (e.g.,
timber incometo the firm) is taxed at a
where:
m = (1 - t)(1 + r)
(1 + r)" - 1
r(1 + r)n