U.S. DEPARTMENT OF AGRICULTURE
FOI?EST SERVICE
PACIFIC NORTHWEST FOREST AND RANGE EXPERIMENT STATION
PORTLAND, OREGON
AUGUST
19SO
I
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i
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Pruning. a 38-year-old, .thinned stand of
Douglas-fir on the Voight Creek Experi­
mental Forest near Orting, Washington.
This is how the tree on the front cover
looked before it W3B pruned.
Table of Contents
PaK«;:,
Introduction
o o o
o o oo o
. o •
•
•
•
o
Economic Factors in Pruning
Clear Wood Produced
The Cost of Pruning
o o
Dif f erence in Value
o
o
• o •
o o o a
o
o . o
o
o o
o
c
o
e .o o o o o
f o· o o o
e
Application of Prunin
g ·Tables
o .
o o •
o o () o o
Explanation of Prunin
g .Tables
Douglas-fir
•
o
o .
• o o
o o o o ()
o
o
o .
o o o
•
y
Mortalit
o
Ponderosa Pine
•·
o • o o
.. o • • •
o o
· • •o • o •
o o o o
Appendix
0 .o 0
• o • 0 o • ••
0
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0
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• • o
·
0
0
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•
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. o
o
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.
• • •
•
•
o • •
• o • o • o •
o o o • • •
o
•
•
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•
• • • • •oo o o
o o
o • o •••••
o o.,o o o o o
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• • • •••••
o o o o o
· · •• o • • o
o • • • • •••
•
•
0
0 • 0 • 0
o oo • o • o
•
Tables Showing Cost of
Clear Wood
Literature Cited
o o . o . o o
oo o o o o o o o oo o o • o
How to Use the Prunin
g Tables
0 0
o o o
.
o o oo o o o o o
o o o
o o ••• o •
• Q
o o o
• • • • • • • • • • •·• • o • o •
o o oo o o
Conclusion
o o o
e
o
o o o
·
Growth Rates
Time Studies· and Cost
Analysis
Mortality .. . . .
;
o
•
o. o
o
o • • oo •o o o o o o o o oo o
y
0 0. 0 0 0 0
o o o o • o
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• • • o
l
o o
o
o o o o • •o • •
••• o • o • • •
• o • oo o •o •
•
·
Other Applications
Q
o .o o
• •o o .
Growth Rates.
o
Time Studies; and Cost Anal sis
o o o .
.
o o o o o oo o
o o o o o o oo o o
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o
2
• • o • o o o o • •
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•• • • o • • •
o • • • o • o ·
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0 0 0 0
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2
3
5
6
·
11 12
13
14
16
16
17
19 20
21
25 29
30 .32. 44
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1' 1:11,'1'
List of' Tables
Title
No. -
1. Page
Pruning time and oost,per tree as related to
d.b.h.--bougias-f'ir at Voight ·Creek
·
Experimental ,Forest
Probable cumulative mortality' in Douglas-fir ..
Pruning; time and costs per tree .as related to
• •• • •
• •
• ••• •••.• •., • • Q . . . .
diameter classes in average stands of pon- .
derosa pine
Probable mortality of ponderosa pine crop
<•
trees selected for pruning
How to use the tables--hypothetical examples
•• • •• •
4.
5·
6. • • · · · · · · · · · · ·
· · ·· ·· · •• ••• •
• • • •• • • • ••• • • o .
Cost of clear wood per dollar of :tni tial prun
.
c
••
ing- cost9 by average d.iruneter growth pe:r decade
and by specif'i ed interest rate"" o •• • • •• .., ... •
·
?.
•'
,,
Cost of clt;Ja:r wood per dollar of initial p:run.
ing cost9 by years to reach attained·d.b.h.
and by specified interest rate
•
••
• • • • •
13.
•
•
•• •
o
Pruning cost per thousand board feet of clear
wood produced - Scribner rule
6 inches
D • b .h. of' tre'e when pruned - 10 inches ••
D. b .h. of' tree when pruned
11. inches ., .,
D.b.h. or·tree when pruned- 18 inches • •
A"
D. b .h. of tree when pruned -
•
•
B.
C
D
•
•
·
·14
16
20
21
30
32
34
36
38
4o
42
M:.st of Figures
l. Diagram of pruning allowance for a tree 10
2..
3. 4. 5.
6. ino·he s deb .he 0 0
1;1
0 • 0
·a·. (I • <o 0 .. .. 0
Diagram of idealized sawing to show utiliza• c
0 .• <I •
0
6
0
0
.•
e
•
tion· allowance
•
··,ttained d.b.h. as related to age in fully­
· ••••••• ••
••
• •• • • • o ••
11-J.
• ••
.
••
0 0 -o
•
•
••• •
stocked stands .of Douglas-fir(
Normal 10-year growth in d.b .ho. outside bark
by Keen's Tree Classes - ponderosa pine (1) •
Rate of d.b.h. grovvth and interest as related
to cost of clee.r wood produced by pruning
.
••• • •
Effect of d.b.h. growth end interest on the
period of' minirr.um costs of' clear wood produced by pruning
• • o • • • •
•
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• •• •• o •• •
•• •
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o
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•• .,
9
10
15
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18
o
22
• • • • ••
FINANCIAL ASPECTS OF PRU1UNG
By
Elmer Wo Shaw and George Ro Staebler Paoifio Northwest Forest and Range Experiment Station Puget Sound Branch
·
INTRODUCTION
Fifty tho us an d acres or about 10000,000 young forest
·braes have been pruned in Oregon a nd .vre.shington during the
past 20 years o Most of this .pruning has been don e in
pondero s a pihe0 possibl y 1,000 acres in Dou glas fi r o
these figures s eem small indeed when compared wi c:h the
an·tioipated demands of' the f uture�>. f'or it has been estima.""
But
=
ted 'that We
need to.
prune
!!J!..er1f. J{!}S£o
S'C9.X'ting Xl.OW D
45 9000
a.ores_in the D ouglas-f i r region alone jus to provide the
vol'U!Ile of high-grade logs needed to sust n plywood produc­
tion at cUrrent levelso
Clear timber for· other uses 'Will
r•equi:ra large addi·bional'. areas
At present less then
. one :·percent of the :required Douglas-fir acreage is being
(g) Y
pT�.:�-ned annuallyo Pruning in ponderosa .pine has been more
extensive[} but till it does not meet the a nticipated
·
future demands/}
One of the rea s ons for this failure :eo prepare f'or
expected needs is the lack of inf'orma.tion and experience
in the long-term finenci al aspect of pruning o
Neither
private companies nor public·foresters wish to inv st
money in extensive pruning unless they can be assured by
convincing oaloulations that it
· The limits of prof­
The
itable pruning .are often narrow and not well de:('inedo
.
major problem
then, is to find out in terms of dollars
'and
cen ts vihioh ·are the best trees for the l ong;=term
]}
Numbers ·in perentheses refer to Literature Cited, p.
ing investmento
prun
..
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It is the purpose of this publication to provide such
answers in a form that c an be applied to any species under
a :wide range of condi·tions.
Naturally, a problem so vari­
able and complex cannot be reduced to a simple equation.
No amount of.research can completely take the place of
seasoned judgment and broad experience; and yet, judgment
and experienc e alone are not suffic iento Consequently,
these tables and guides present d here will.be
st effec­
tive when used to supplement experienced judgm nto
ECONOMIC FACTORS IN PRUNING
The ultimate profits from pruning are determined by
three factors: (1) the amount of clear wood produced; ( 2)
the total cost accumulated at a· chosen r ate of inte rest
for the required number of years; (3) the difference in
value between c lear and knotty wood at the time or harvest.
These factors may be combined to give the follovdng
prori t equation:
' '.
.. :.. Profit:: volune or clear wood produced x differ
e in
value-(prunint; costs x interest :ra.te).,Y
. :. .
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.
:
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Clear \'foo d Produced
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The fundamental purpose or pruning is·to produce clear
wood; consequently, the rate of growth on the pruned section
is of primary importance in de ermining the profit from
pruning. This growth rate may be expressed either as an
increase of d·.boh. per decade or as rings per inch0 The
diameter growth rate usually decreases as the tree matures.
Even in thinned stands it is difficult to maintain a
constant r ate; therefore, in applying the tables of this
publication it is important to select a repre entative
average covering the period between pruning and harvestnot just the curren t rate of gro1vth.
--------�- ----------
Interest r ate at the.chosen rate c ompounded annually
n
the familiar loOp where p':: interest rate and n :
number of years.,
Computations of clear wood production for this paper
are based on date. from the first 16-foot log onlyo Trees
are often pruned to heights of less than 18 feet9 and o ce.­
sionally, with the aid of olimbing.spurs to 2 log height o
Howaver9 the basic 16-foot log9 or 18-foot pruning, is the
generally aooepted st dard and9 therefore0 this height
·-was oho�?en: for study'o Because not all the increment fol­
lowing; prUning is Olear 1 ar!.d· not all the Olear WOOd Can be
utilizedp some deductions and allowances are necessary :ln
computing ·the amount of clear wood produced. These deduc­
tions are discussed later in the publicationo
Th .Q2st. ?:t..Pruning_
'When pruning is· considered an investment that is
til re·burn a profit, the tots.l' cost will include three items: (1) in:i.tial costs per tree$ (2) allowance for mortality and e:r:ro:rs; (3) interesto Many factors make up the :'l.ni tial cost of pruningo
The roost important of these is the labor cost, or field
t;i.me actually spent on the job.. The effectiveness of
this field time in terl!l£i of' ·trees pruned per man-day is
again governed by se·veral factors 9 many of which are hard
to evaluateo These include:
(l) Branches- number, size9 and condition (live or
dead) o
(2) Danai ty of tocldng--ma.neuvez:-ing; room.
(3) Topogre.phyA slope, ground cover. Weather conditions--snow, rein, ooldo
Height of p:ruriingo Tools and methods usedo 7
( ) The human element--administre.tion9 training0 attitude 11 morale, and inoentive o
4}
(*
Tree diameter is often u ad· as an index in time
studies because it is easily measured but its reliabili t,y
is dependen-t:; on the correlation between dit::Ulleter and the
number, size 9 and oondi tt on of the branches. -3-
1:
1
In addition to the p runing labor" other charges to
consider are:
(1)
(2)
( 3)
(4)
Tools and equipmento
Filing and maintenance o
( 6)
Tree selection and :marking.,
Transportation or camp expensec
Taxes
and insuranceo
( 5) Superili sion and. adminiatra tion.,
Existing time stLldies are good as a gui de but c annot
used as a11 infallible rule in predic ti ng initial costse
would be advisable on most pruning jobs to conduct
short trials in the field.� compare results with existing
studies, and ·then make whatever•adjustments seem-warranted..,
be
lt
mortality or los se s from mis­
judgment.., or other causes o · Not all ·bhe tree a
pruned will live to be harvested as planned o Some ·will
die 9 o the rs will inevitably be badly da:maged9 and somE! will
become suppressed or fail to make good gr ow th o All these
losses must be distributed over the pruned trees that do
survive and a:re out., and the .loss should be a.llow'ed for by
increasing the i tial c os t per tree.,
For ax
ple, 100
trees are pru ned at a cost f 50 cents per tree or $50o00c
Twenty percent or the trees die or fail to make crop trees
the reroroning 80 trees must bear the total ;p runing cost.,
The second cost item is
takes , poor
Initial costs must then be computed as
cents per treeo
$ 50/80
or
62-1/2
After the initial pruning cost pe:r tree has been
determined by time studies or other methods, a nd proper
adjustments have b een made fo:r mortality and
loss,
interest--the third· coat item--should be oomputede
This
is done by accumulating the adjusted cost at the chosen
rate of interest for the desired number of years.
Select­
ing the interest rate is primarily a management decision.
The long-range program of the owner should determine at
what :rate of interest he is willing to invest his money ..
-4-
Difference in Value
Finally 9 the prof'i ts in p:rt.tning wi 11 depend on the third economic f'aotor--dif'ference in value between clear ·and knotty wood at the time of harvests This dif'.f'e:renoe cannot be aco ately predicted 4o to 100 years henceg but it should be safe to assume that the dif'f'erential 1.vill :not decrease o Consequently 9 the curren,t prices can be used 1!us a gu:tda<�·. For example9. the cost of pruning· could be weighed against the dii'f'eremoe in 'll;alue bet"l'reen peeler grades and sawmill g radeso. In Douglas-fir a premium of $25 to '$.;o per M is. now paid for peeler grades o This premium is paid ·on the total scaled vo!tune" not jus·t the amount that ·is clear, though this practice may change in the t'utureo For a OOMern tha.t manufactures rumber or other products from its own pruned trees0 however, the di.f't'erenoe in value of· clear and knotty wood in ·bhe final product is ·the ·real crl terion of value difference. The f'aot that t:rees will eventually prune themselves naturally has often been presented as an argument against· arti icial pruning
At least t is olai.med that not all ·che increased value· should be att;r-ibuted to. pnming since E�qme cl<?ar wood might have been produced anyhowo This way· be partially .true in some cases, but in ·general the ·bime ··re.qtd.red to prod:uoe cl ar wood without pruning is far oo g:ree:t· to give :muo weig}?.t to the argument o For ex nple, research conducted earl er by the Pacific North­
west Forest and Range Experiment Station has shown that in average stands of' Douglasc.f,'ir as rm:wh as 100 to 150 years a:re lost before a tree starts producing commercial .clear wood in t he first 16-f'oot l og (£) o ..
·
·
!ri order to realize the
imum returns from prunings
permanen.t records of' the areas on which trees are J?runed
and d te of treatment should be ni.a.ae. If'. individual
trees could be pe:!.'l.na
. nen·bly marked9 it would also help o Mu h difficulty has been encountered in Europe
pruning because this was not doneo It is especially important when.periodic thinnings are planned. Years later, after other trees have pruned t.ltemsel ve.s naturally' it will be
·
·
-5-
1
<
imoossible to tell 't:hich trees were pruned in the original
tr e atrl\ent unless they can be identified. Accurate records
and maps ·will help but an inexpensive permanent marker for
individual trees needs to be developed for this purpose.,
EXPLAlTAT!ON OF PRUNING .1,�
The p rm1ing tables grouped at ·bhe end of this repor 1
show· how much it costs to produce clear wood by pruningo
The cost per thousand board feet shown depends on ·bhe
volume of clear wood gro-vm and the aocv.mulated costs. of
prunine;o Hence only a few factors need to be as sume d ·to
construct tables which are a pplicable to all9 or nearly all,.
oond1. tions.,
The growth of clear wood vvas related to three var ie ble s 8
.
(.lob oh. of ·!:;he ·bree a t time of pruning; average growth rate
for the years after pruning; and number of yeflXS after prun=
ingv Growth in board feet was taken as the difference in
scale between the lrnotty core of the log and the entire log
af'tel:" clear wood has been g:rovmo Since log sce.le is based
on the diameter inside bark at ·the top9 or. small end or ·bhe
1og11 measurements must be converted ·to scaling d..tanl€lter of
the log. In oonstruotine the ·bables8 ·it was assumed that
this diameter is 80 percent of doboh•p both at the ·bime of
pruning e.nd after gro·wth has te.ken place o Form class 80
(the ratio of doiobo at the top of the first 16-f.'oot log
to deboh.) is representative of many ponderosa p ine and
Douglas-fir stands of the Pacific Northwest region and is
also a good average for many species the country over" It
is recognized ·bhat in innnature stands of the ·type no:cmally
pruned9 form class improves as the ·bree grows olde:r and
the stand closes. Hence8 the use of the same form class
.
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In l9Lt9 Glen Jorgensen developed a somewhat similar
table showing the estimated rate of.' interest ·bhat the
pruning investment would earn during the expe cted rota•
tion p eriode His table is being used·on the Umatiila
National Forest in Oregon as a field guide f.'or ·select
ing the ponderosa pine trees most desirable fo pruningo
I
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.
for the ·brae when pruned and after growth means 0 on the
average9 that the initial scale of the log ha s been over
estimated9 lending .some conservatism to the board-foot
growth ..
The scaling diameter of the log when th tree is
pruned was increased in computing ol e ar w ood production
to· a.llow for three thingsg
bark thickness!! he aling of
rounds!! end utilization praotioee
The double bark thick
ne s was allowed for because under ·present pruning
praotioe the branch is sawed flush with the out s id e of
(fig., l)o
The cambium layer must g.row outwal:'d a
thickness of the bark before clear
'WOod .may be grown across the branch s tub o
To allow for
this required growth9 the soaliP
diameter of the l og
when pt ned was increased by the follo;rl ng amounts:
this bark
di tance equal to th
Trees
t1
w
"
6
10
14
18
inches .d.,boho
n
yg
it
it
ff
n
c5
loO
lo 5
2o5
inches
99
"
11
As to healing of WOU11ds9 little data exist that show
hovr much the tree :must grow before wood laid on beyond
the end of the branch stub is usable clear \VOOdo
Disseo ..
tion of some Douglas=fir pruned trees has shovvn tha t
where b:ra ohes as large as one inch in diameter were
sawed off evenly 9 usable wood is laid on right next ·eo the
sawed suri'aoeo
Not all the clear wood grown by the tree can be uti­
lized9 at least under existing praotioe o · The Scribner log
scale allows for this in the scale for entire logs
Since
clear wood is lai d on in a shell conf.'oX'Illing to the taper
of the first log9 an additional allowance must be made o n
the inside of the shell=-or around the knotty core.. Dia­
(
..
fig 2) or idealized slab sawing of l-inch boards
grams
showed that an allowance of one inch in diameter (or a
inch shell) on the knotty core will compensate for the
theoretical loss
o
It is fel·b that this will a lso take
care of the healing allow oe8 though it may not be ade•
quate for this purpose when unusually large dead limbs
are pruned.
-7-
The adjusted diameters rtnd scales of the lrnotty cores
used in constTucting the p runing tables were:
Utilization
Ba:rk
& healing
thiclrness
D.b.h •
•
80 j.�o !].lovre.n��
4.8
6
10
e.o
14
18
11.,2
14.4
+
+
+
+
_
o5
+
lo5
+
1.0
2 .5
Diameter
of
a1J.�!!-lS!loi.� core
+
+
loO
loO
:
""
-
loO
=
loO
""'
Bd.ft.,
sca le
6.3
10.0
13.7
17o9
15
55
117
213
The scaling diameter of the log af'cer the tree has
laid on clear wood is simply o80 d.b.ho and the difference
in scale betv1een a log of this diameter and the knotty OOl"e
is t he boa:rd··foot growth of clear wood"
In the tables data
are given only for trees in which the final pruned log i ­
at least 8 inches greater in diameter thun the kno·cty cor<E�9
equivalent to a shell of clear wood 4 inches thicko
Cost of pruning9 the second factor upon which the coat
of producing cleo.r ·wood depends!) was based on assumed ini""
tial costs accur.rulated a t various interest rateso
!n the
short tables,6 end 79 only one initial cost is assumed0
*:LOO per tree9 and chis oost is accumulated at 2s 2=1/29
and 3 percent interest rateso Val ues for other pruning
cost rates may be computed by multipl lng the figures
given by the appropriate initial coste
(For a g;iven set
of oonditiona the cost or· clear w ood is proportional to
the initial pruning costo)
In the expanded tableD Noo eb
initial pruning costs ranging from $Oa20 to $le00 have
beon used, and these were accumulated at the 2 1/2 percent
interest
rateo
-8­
.
....--8"
.-· --.....
lOp d.i.b. I€! 16'/og
l
16' LOG
FORM CLASS 80
J
end
a
J<notty core
b
Bark
G
Uiilization allowonc.e
allowance
d
Clear wood
e
Cambium
+
Bork
(healing)
prodoced by pruning
STUMP
Tic:Jure 1-- Dioqrnm of pruninq ollowonce for a free 10 in d.b.h.
-9-
·I,
Diameter l<notty core
Area
of dear
-
8 inches
not.
utilized
(shoded portion) 13.7sq.in.
Area of
allowance
(inside dashed circle)
-
l:i.3 sq. in.
Diameter
knotty
core
-
15 lnc.he,-;
Area of dear not uiilized (shaded portion)
110.5 sq. in. Area of allowance (inside dashed circle)
24.4 sq. in. -
end
Knotty core
b
d
Clear wood not utilizable
os
.such
Allowance around l<nofly coro
-fur clear wood nat- used
Clear wood
2
Diagram of ideolized sowinq io .show utilization ollm't'"
once. Waste in deor wood is based on slob .sowing of l-InCh boards ·
and .1/4-inch saw kerf. Allowance mode for waste is o 1/Z inc.h bond
Fiqt,rre
around
--
the
knotty
·
core.
-10­
APPLICATION OF PRUNING TABLES
The pruning tables are. applicable throughout the
Pacific Northwest or wherever pruning as a stand improve=
ment measure 'fs 'being 'p'r.<1cticed.
The tabies were desig'ned
primarily for ponderosa pine and Douglas-fir
hut they may
be. applied equally well to any stand where the assumptions
made in table construction are reasonable.
form class of . 80
These are
a
and a healing and utilization allowanee
on the scaling diameter of the log ranging from 1.5 inches
on 6=inch trees to 3.5 inches on 1.8-inch t rees,
these assumptions are not exactly correct,
serve as useful guides.
Even where
the tables will
ith the advent of power pr ning -already a reality
on an experimental scale--the financial aspects of proper
tree selection will gain a greater emphasis.
Power equip­
ment is bound to change present pruning practices in many
ways, and guides will be needed to evaluate the delicate
inter-relationship of the different cost factors involved,
These tables should help to solve just. such problems,
To use the tables
the following information should
be known or estimated:
(1)
Diameter of tree to be pruned,
( 2)
Average rate of diameter growth between time
(3)
Total pruning costs per tree,
(4)
(5)
Approximate age at time of pruning.
of pruning and harvest,
including an
allowance for risk and mortality,
Rate of interest.
"When these data are known or assumed, the following answers
may be taken from the tables:
(1) The cost per M of clear wood produced a given
( 2)
The period at which the cost per M of clear wood
minimizes, i.e., the period at which it is pro­
number of years after pruning.
duced most cheaply.
',
'i
'i
,,
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By comparing these costs with the actual or
(:3)
assumed difference in value between clear and
knotty wood, the margin of profit or loss on
any parti ular tree may b determined.
( 4) By
insp ction and comparison, the tables can be
used to show· the relative e ffects of\ changes in
y of the important variables, eog., diwne er,
ti 9 costs, growth, .or interest.,
·
· ...
D ouglas-fir
.
st ds present som pr9.plems: e.nci ,cond.i
As 1.1\ resuH; diff'e!'ent
tirl:ms not found in the pine ( p ge 17 )
figures :must be
. u:;;ed for growth ra.tes9 diameter9 cost per
tree 9. morte,J,.i.tY 11 . etc· .,, wh,en applying. thE} pruning tables.,.,
'
.
.
.
• '·
·
'
'
f.e wr - of
'
· -'
g
are di.f'fer.ent
, even-aged9
dense.
;in
Ymen Douglas-fir. trees. occu:r
aho
puure se ond... growth· stands9 .20 ·co 50 ye a r s old.!) the limbs
ere' usually ,dead to well. above 20 fe e t a.nd in, ;mo.st ce.sel:l
CBJ!l be readity b roken off w-1 thin the bark by a sharp blow
wH;h a Hebo.club9. .The Hebo club is a tool.designed. pri­
It is imply a short
meJL'ily for pruning in Douglas-fir
cl'oJ.>b something like a ball bat 'With a meta1 shield e. round
the striking surf'acee The ·limbs. that ca�.111ot be ·res.ched oX"
removed. sat sfactorily wi·bh the club are: pnuied. m th sawso
qe.rtain
·.
,Pl'.\illi n
practices
.
• .
o
.
If' cutting in sec on.Q.-grC,wth Doug'ia; -:f'ir .begins as
.
en
e arly commercial .. hinning�,� px:.uning can be dorie. a.f·cer the
tmnningo This combination has several advantages:
Growth is stimulateQ. by releaseD ar as' are made. more
cessible, costs' are'reduced and better selection is
possible (12) (13) ..
'
'
...
·.
-·. ·
8.0"'
-
Thus far 9 pruning in Douglas-fir has been quite lim..:
i ted, ,, u as sl3 nd-:growth stB!ld . come _}lnder management
:
,
e.nd as' Virgin timber, grows more sca c each year,· pruning
wi}J. li ely become a.n established practice,.
-12­
.
G:rovrl:;h Rates
The information availe.ble indiot _-tes that in natural
ulimwlaged stsnds of normal stooking1, a dobuhc- growth of
2 oO :.tnches per decade during the period f'ollowing pruning
is about the maxi:mum on the better sites (see figo 3) o
It would be unrealistic to assume that the grovlfth rate at
the time of pruning would continue undi:rninished through""
ou·t rotation in v.n unmanaged stand
However., if' p eriodio
thimlings rmd intensive management are pt"o.cti::::od cr
ple.:nned 0 the growth rate may be sustained or perhaps
stimulatedo In one thinning and. pruning study conducted
in a hO=year· old st�?.nd of second=growth Douglas=f'ir on
site III at Kugel Creek on the north side of the Olympic
Peninsula. it was found that the di0011.eter gro1v'th rate
during the first 10 yee.rs following thinning increased
o6 inch» that is from L7 to 2o3 on a 12=inoh ®.vere.ge
tx."ae ( 15) ( 1l) o Future periodic thinning in this stand
may notcontinue to increase the diameter growth rate
appreoie.bly P but if tl-J.e present rate can be maintained
an obvi.ous advantage vr.tll have been ga:i.nedo The trend
of the curves in fig,. 3 also emphasizes the advante.ge
of pruning before the growth ra tes d e c line o
a
'i
II
Managed forests in Denmark present an even more
striking exel!i.ple of growth,. Danish foresters are produo=
inz; under management more tote.l cubic feet volume from .
their Dougle.s=fir plantations on site III than is found
in natural untbi:nned stro ds on site I in the Pe.oH'ic
'Nor'thwesto In one of their 66-year-old stands on site
III 9 the mean annual diameter growth has beeri 37 inch
.
or 3o7 inches per deoe.de (6.4 rings per inch)
•
(2)
(4).
-13-
'.'1
:
,,
Extensive time studies or cos"l;; Emalyses have not
been made for Douglas= ir pruningo The data.sho l in
1 oa.n be used· as a g;uide o They are from a small­
scale study at the Voie;ht Creek xperimente1 Forest n<:J!!!l"
Ortine;o Ws.shington17 cim.dmd:;ed in 1949 in et :�m· yeeJ."=olcl
t;hirmed s·be..nd (12)o .f.,,bo rt lvOOO crop t:reesn r angin!!'
.n s:i. ze f'rom 5 In hes to 1)-J. inches d b Qho 0 rox'e p:ru;;:etL.
The bas:tc oo::d::;· pe:i." hour' we.s figured o:n a vm.g;e J."r .'l:;a oi'
1 o35 plus '21l )';o:r other items or expense shovn1 f'o:r
oosJcs in pine (page 19).,
te.ble
I .
·
Table
...
=
---
l o =J?:run:i.pg ·time and cost pe:c t.re:1e €:'J'l
1:-elated ·co d ob oho Dougle.s=f'i:r e:c
Voight Creek E " perimelrba1 Forer:rho
--��=..,..,__�
����
Actual pruning
Doboho =---time --+· Tph•.l
. Mino
Hrs o
Min.
-·
2.00
6
7
8
9
10
11
12
13
14
2.43
2o80
3.07
3 o 35
3o60
3 o8 0
3o98
4 10
4.20
:..F
o033Ll
0! 05
o0467
.0512
.
0559
o0600
o0633
.0663
o0684
o0700
i,rrt
�=-�
l Hrs_ l Lh!._o
5o25 . c0875
6o38
1063
'7o35 .1225
8.06 .1343
8 .,80 "1467
9 o45 o1575
9.98 o l663
10o45 o l 742
l0o76 ol793
llo02 cl837
Cost _a-i:;
OoJ1.ol7
o20
.22
o2l1.
o25
27
o28
o29
o30
=
!10
I
Dominant Trees v
r-- - - Codominont Trees C!
0
w
_/
v
/// /v... ., ...
//v/ .......v
..
· 'v L//
v
z
20
14
12
10
B
/
p.,
18
1(,
/v ./
/
22
:.c:
tci
v v ./
....
'
---
,.,. ..... ...
-
-
_;_--
�o-----
.....
/.,
/v,.
v
l/ y L
v·
/
l/p
-
-
,_.
·
�---
.. -_;:.::::
-
_,
-
-
... -
_ ..
.. --
--
-
!--"'" -!>--- --
-
�-
.,....,..
-
�------
--
---
--
I
0
50
AGE
70
IN YEARS
fiqure ; -:.. Attained d.b.h. os related io oqe in fully stocked stands of
Dooqlos-fir
II
( 14)
'I
I
-15-
Morte.lity
Table 2 is from records of mortality on permanent
sample pl ots throughout the Douglas-fir region.. It may be
used as a guide in estimating future mortality of p runed
Of course 9 under management and
trees in natural stands Q
periodic thinning9 it might be pos sible to reduce these
·
rates
Table 2.--Probable cumulative mortality in
Douglas-fir"
Years after
runinf!:
10
20
30
4o
50
6o
70
80
90
100
Percent by number of trees
Dominants Co dominants Ave:ra._g_e
2.3
4o6
6 o9
9.2
ll.5
13.,8
16.1
18 .4
20.7
23.,0
4.,8
e6
1 ..4
19 .. 2
21-!. .,0
28,8
33.6
38 .L
43.,2
48.0
3 ..5
7 .. 1
10o6
llh2
17,7
21o3
24(18
28.,4
31.,9
35 ·o
Ponderosa Pine
Pruning in the pine region has it s o1.vn special prob­
It has been found that the trees whose growth rate
Il"..akes them mo s t desirable for pruning are quite of·ten the
open-gro n. fringe type with numerouss large, live limbs .
persisting almost to the ground a .'With current methods of
hand p runing 0 the cost .and effort required to prune such
lerns.,
trees has often been prohibitive.,
-16-
On the other handg treos grovnnG in dense sapling
patches may have small8 dead limbs and therefore be much
ea:sier and cheaper to pruneD but this seeming advantage
is often mlll:i,!'ied by a slow grovrt;h rate -almost stagna
tion in some· stands
• .
The problem ·then is to know just where to strike a.
comp:t•omise that will yield the greatest return on the
long=·berm pruning investmento Without aome kind of' sn
eoonomic guide,
such a decision :ts extremely difficult.,
The tendency now is ix.rward th.e selection of the fast
growing type with the hEJa1ry9 live limbs o This change of
attitude has been the rtHml·c of' several yee:rs of exp;n·i=
ence and experimentationo
At least one tool company is
now develop:l.ng; portable power units
and nrl.dget chain saws
for use in ·fuese opendgrown pine 8tandso
Considerable
'When sihiculture9 eeo=
nom\cs0 and !0.9ohanlzo.t:lon are all oonsidered8 deciding
whether to pnn:te becomes an even roore oomplex task.
progress has.already been· made.,
..
Growth Rates
o:=---=-=
l!,l:':Q
-"<!>
.......,
One of the first factors to consider in selecting a
prunl.ng a:rea4 is the a:verage :ra:'ce of diameter gt"ov.rth on
the s itable treeso Increment borings and ring oounts
Length o:t' leaders and
oan be used to get e. general idl8aa
paoa be Neen whorls are also good indicators of growth
dif'f'erenoes.
The cur :rent growth rates obtained. from. ring
counts and :measurements should then be convex·ted or ad­
jusi;ed to average diameter growth per 10 years for the
pe:r.iod between pruning and harvests
Grovrbh studies and
·
ourves maybe used as guides in.estimationo
The growth
curves b a sed on Keen9 s Tree Classes Bhown in fie;.,
p:repat•ed from an
8 9000 tree
L
were
sample eolleoted from virgin
pine stan(1a in eastern Oregon (!) o Under management or
.Beleotive cutting an aoceleration may occur. !none
dy (2) it was found that 20 years a.f.'texo seleo·t:i..w
s
outting0 ·l:;he trees in the reserve stano. showed e.n increase
in die.med;er gro1:vth ·the:b varied from 32 peraent to 88 per=
oentQ When the most promising trees have been selected
and any expected release allowed for0 the curves in fig. 4
should _be conservative for young pine stands.
1.8
.....-----,.-'"11""'--,
De51RA6LYi
RAN<lE
f,,
OF
_::::____+!--------+-- -----;
PRUNINO
1-.
__
-
tf)
ti.J
:J:
v
......,
::t:
1c::u:
�.:> ..
.s
Og
Ll.l
tu
:2
<!
i5
.1'0
.2�-------+---�--�
AGE
CLASS
Normal 10-yeor qrowih in d.b.h. outside bark,.
in natural stands, by Keen•s Tree Classes -Ponderosa Pine(!)
fiqure 4
--
-18­
Time S tu di es and Co s t Analysi s
Mo st of . the earli' r t;ime< stu'di e;s· in: pondero s a pine
be used with c htion 'in 'fiXing pruning co s ts
Thes e studi e s co rrelate d d ob oh o of the . tree .with the time
re quired fo r pruning (1) o ln s o me oa.se s 9 .how ver 9 thi s
correlation do es no t hol d true unl e s s the >rel ation to ·
d ob eh o i s dete rmi ne d separately for the open grown .type
and dense or ave r age s ta.nd s o
shoul d
o
Current c o s t records and time s tudi e s in the fi l e s
of nati onal f o r e s ts where pruning i s bei ng done are proba=
bly more s.p plioa.ble than e arli er work . pub li s he d during
the CCC days o During the 1949 s eason the average to tal
cos t per t:t•ee i n'. the Pacific Northwe st wa.s 50 c ents o
Practically all o f thi s work was done in ponde!'o s a pine 8
and the c o s t includes super1 sion 9 marking 8 transports.=
tion 9 e quiproent 9 maintena.nce j) and numerous o ther items
in ad di ti on to actual labor ., Much o f the pruning was
done during the winter under adve rs e condi tions and on
large= limbed tre e s 0 The SE1 c o s t s D or any e s timate s for
tha·b matter 0 wi ll always vary wi th condi tions and · should
be :mo difi ed whenever o n- the= g;round expe ri ence shows it
to be neces s ary .
Table 3 :may be used a s a. gui de 'in e s timating ini ­
ti al pruning co s t o I t i s adapted from a 1942 time study
on the Whitman National Fore s t ( 7 ) . The total c o s t per
mAA-hour of' $L45 i s hypo thetic al but i s fairly close to .
current 'Tage leve l s o I t includes the f'o ll ovring items:
Wa ge r a te
S upe r vi s i o n
o o o o
•
.
o
o
.
o
o
4
•
•
•
•
•
• •
e
• • • • •
. .
o
C:f
• •
.,
•
•
•
• •
o
• • • • •
• o o q a
o
o
•
Q
• • • • $
• •
•
•
.
•
•
•
o
• • •
o
• • •
• • •
•
•
•
•
•
Indu strial . insuranc e -
3 .85%
Medic al aid
Social s ecuri ty - 4 .oo%
Transports.tion
Too ls and maintenanc e
o o • • • • o
• •
o
•
• • •
.
• •
Total
• • • •
·
•
. •
• •
$ 1.20 0
. 06 0
.o46
o005
.o4B
.o47 .·
. o42
$ 1 .448
; ,
-19­
. ._
·, · :
Tab l e ; . --Pruning time and c o s ts per tree as
r e l ate d to di
age s t
eter c l as s e s in aver­
d s o f ponde ro s a pine
Pruning
time
To · al
Total
M i nu te s
i.1inu
te s
--
Hours
D .b . h o
only
-
I nc he s
---6
4 ...90
7
8
5 .93
7 o00
7 o9 0
9
10
8 .75
11
9 .60
1 0 .3 0
12
13 1 1 . 00
11 .60
14
· 15
16
12 . 1 0
12 . SO
time
9 .84
10 .87
11 .94
12 .84
13 .69
14 5
15 . 21.J.
15 .94
.
4
16.54
17 . 04
1 7 .Wt
time
.
1640
.. 1812
. 1990
•
.21 .0
.2282
. 2h24
.. 2540
. 2657 . 2757
. 284.0
. 2907
(I) •
Cost at
$1
.45Litr
--
.24
.26 .29
.31
.33
o 35
.37
.39 . 40
.1 .1
14 2
.
Eortali
-.BL,
As provi ou s l ' mentione d , th-e actua.'I pruning c o s t
shou ld be inc reased to al l:ow for hi dden o o s ts ..P such as
mor tal i ty of' pru:n.ed tree s and judgment e r ror s :in seleo ...
ti on of tree s . Damage or mo rtal i ty might . re sult :f'rom an r
bark beetles .9 fire .II porcupine s .; di s ­
or several causes:
eas e ; insects , s to rms
li ghtning .- suppres sion8 e tc .
The
all OvU�Ji.C e fOI'· thi s ri sk cannl.)t be de te rmined exac tly s but
the peroerrb to inol·ease c o s ts c an be e s timate d from mot­
tal i ty
s tu di es .
Table 1-t
·taken from
a
·whi ch may be useful fo r thi s purpo s e , i s
s tudy o f i ns o c t-c e.u s e d mor t!\l i ty ·l n pon­
:Keen T ;ee Clas·s e s and inc lude s tre e s from
11-J. i nches · d .b .h . , mo s tly . o f tree . o las s e s lA n.nd lB
(.!Q) . The da·ta in table ' 1+ may iead to l ow . . e s tima:te s of
dero.s e pine by
0 to
mortal l ty oos ts , ' for the s tudi e s were b a s e d only on tre e s
that dte d s·tand:i.ng ancl do no t include wi ndf'ull mortal i ty .
Howeve r 1 thi s may b e parti al ly o ompens a ted for by s eleo·t­
i ng o nly the mo st p romi sing tre e s for pruning-.
-20-
Tabl e 4 . = -Probable
mor tal i ty or po n
dero s a. pi ne
crop tre e s se lec
ted fo r pruni ng .
,----.,.
Cumulati ve mo r tal
i ty
Ye ar s
b number of
tre t s
after · Vlhe" PM!rie
d Whe
!l g at a e 0 at an eprUlie d '
"'
L -.11:. -ll
Pe rc en t
--........___________
30 4o 50 60 70
80
90 10 0 110
120
130
14o - 1 50
6.o
. e .o
10.0 13 . 5 17 . 0
20 . 5
24 . o 27 .. 5 31 .0
34 . 5
38 . 0 41 . 5
45 . 0
6 .. o
9 .5
1 3 . 0
16 . 5 20 . 0
23 • 5
27 . 0
3 0 .5 34 . o
3 7 . 5, 41 .6
---- -- --------.......... ___
__Q ______
l '�UnOd
-
--
1 0 . 5
14 . o
17 . 5
21 . 0
24.5
28 . 0 3 1 .5
35 .0
--------
...
....... - . - ·
-- ... Asi de fro m t hei r
us e for a parti c
pruning job , the
u l a r spe ci e s o r
pruni ng; tab le s ar
e 'Valu ab le ai d s
unde rs tandi ng how
in
the vari ous facrt
c l ear woo d .
o r s ' a ffe c t the c
Suc h an Und ers t
os ·t o f
anding wi l l hel p
ed- -fro m manag
all c oncern­
eme nt to the man
on the end of the
· make in tel l i g e
s aw- to
n t deci s i ons reg
ar ding p runing .
The mo s t imp or ta
nt
va riable influe
woo d i s the g;ro
nol ng
c o s t of c l
vvth rat e ( fi g .
e ar
5) . Obviou s l y the
a. tree gro ws the
fa s ter chea per wi l l be
the wo o d produc
no t so app ar ent ,
ed9
bu t
pe rhaps , i s the ra
pi d ch ange in co s
smal l c ha.ng e s i n
t wi th
g'rowth rate . Al s
o i mp or ta.n t i s
that s l ow-growi ng
the
fact
tre e s mus t be hel
d so l ong to p rod
J,og s o f the minimu
uc
e
m di ame te r tha t ,
.in mos t c a s e s _,
l ate d pruning
acc umu­
co s t s wil l make
t he inve s tment . i n
p rohi bi ti ve
c le ar woa d
The pre.o tic a.l e ffe
c t i s to make i
ti ve that pru
t imp e ra ­
ning be confined
to tre e s exp ec ted and make ad e
to live quate di ameter gr ov;
th .
-21 -
$40
Assumed :
$'55
r.i
OJ
!l!
8
..J
u
u.
0
8
\J
D. B. H.
""' 10 inches
eo.st ""' 40 <'/.
Term = 100 ye4JrS
.$30
.$:?.5
$ 20
,$ 1 5
.$ 10
.$ 5
.$ 0
Fiqure 5
1.0
--
1.5
z..o
2.5
:;.o
D. B. H. GROWTI-1 RAT!.: IN iNCHES PER DECADE
Rote
clear
of' d.b.h. growth ond interest
wood produced by pruning.
- 22 ­
a.s
loted to cost- of'
The ac c umul ated pruning c o s t i s mo s tly dependent on
inte re s t :r ate ; the refo re , if too hi gh a.n inte re s t is de­
mande d on the pruning i nve s tment, any :reasonabl e increas ed
:ret rn c an easi y fai l to cover the co s t . Thi s i s particu­
l arly true whe re the trees are hel d a l ong time before cut­
ting 9 e i the r be c ause a long rotation has been e stablishe d ,
l
:\
In such cas e s 0 a low
i nte :re s t ' r ate mus t be e.c cepte d if' p runing i s ·to show a
o r b e c au s e o f a s low rate o f' g rowth o
prof'i t "
Diame te r of' the tree a t time o f' p:ru_ning affects cos ts
in a way not u sual ly appreci ated=-that i s 0 othe r things
being e qual o the bi gge r tre e s 1v.l ll produce c he aper
clear
wo o d o
Thi s i s apparent when one s top s to think that a
s he l l of c lear wo o d of' gi ven width around a b i g t re e con
tains mo re board feet than a s he l l of' the s ame 'W-id th around.
a smal l tree o
There are compens ating f.actor s 0 mB.inly in
,
the gresd:;er c os t o f pruning the larger tree s .!) but in ooerh
c a s e s they vd. l l no t be sufficient ·to offset the more favor =
able ratio of. di ameter growth to bo ard=f'o o t growth G
Cost of c l e ar 'vo o cl pro du c e d val"i e s dir e c tly wi th ini =
tial pruni11g c o s ts 0 a s poi nted out earli e r e Thi s relati o n
i s l e s s oomp l i o e:ted than the o ne b e tween di ameter and co s t
o f cl ear wood; consequently 9 i t i s mo :re easi ly vi sual : hec L
The tabl e s a l so s how tha t there i s a b e s t time to har=
ve st prune d tree s fo r pro duc tion of the che ape s t clear woo d .,
The separate i nfluenc e s o f' a c ons ta t di ame ter=growth rate
and pruning co s ts inc re a si ng at a compound intere s t rate
resu l t i n falling c o s t s per board foo t o r o l ea:r wood and
6)
then. a ri sing c o s't ( fig o
e
The time re qui:red to reach
minimum co s t varie s to a certain extenJc with d .,b oh .. of' the
pruned tree and wi th g rowth rate
i s 'i-L th the intere s t rate .,
but the maj o r variation
The higher the intere s t rata
the e arli e r ml s t the tree s b e cut fo r minimum co s t o f clear
m o d e At a given intere s t rate the bi gge st tree s maldng
the faste s t growth may b e out e arli e s t after pruning and 9
conver s e ly 9 ·the smal l e r tree s ma.ldng the slowe s t growth mu st
In mo s t
be hel d long e s t befo r e minimum co s ts are reache d .
o a s e s 9 the c o st o f c l e ar vro o d wi ll pe rmi t a 30-year l a;ti ­
tude in time o f. harve s t , sinc e ,the se co s t s tend t o become
more ne 'ly constant a s they approach the pe rio d o f minimi ­
z a ti o n ( fi g . 6 ) o
.$80
\ %1 ,i7fe f
.$70
ci
m
9'rowf/1,.-/"
$60
MINIMuM1
$5 0
Q
Cf.
...1
v
u..
0
$40 r- Assumed:
...
o. 13. H.
10
inche s
. \'
"-.<
Cost/tree "" 50 4-
$30
/
CO.S TS
.
/C:l.rl--
/.0 <Jrosvfh
__.
$ 2:)
1::1
8 .$10
$0
3% //iferoJ'i
- :JO cJ!VId/7 ---
;2% '/r(e�- $.O lJmwm 1
w
0
YEARS
Fiqure C.
ro
AFTER
oo
100
PRUNIN<i ( HOLDING PERIOD )
-- Effect of d. b. h. qrowth ond interest
costs
m
on the
of dear wood produced by pruning.
.:. 24 -
period
of minimum
I t should be pointed out that the year o f minimum
co sts may not be the ye ar of maximum prQfi t , s inc e pr.t.».t'i t
also depends on the vo l ume of c le ar wood and ·the di ff(er­
ence in value . The tabl e s g;i ve o nly the third e lement
in the profi t e quation--co s t of pruning per bo ard foot
of cle ar wo od .,
HO I
TO USE 'fHE . PRUNING
TABLES
....-"':"'
-------
Myriad combi.n ations could be solve d by the. . .pruning
table s . The suc ceeding examples nr1 pure l:y hypo thetic al;
but they. are typic al of ac tual po s sibi l i ti e s.s . s ome of
which ma.y not s e em r eali s ti c t pre s ent but .which m.ay 9
perhap s 9 beco me easi ly attai nable in the futi.l.re ·., Tab 1®
su..rnmari ze s the c a se examples that are solved here as
detai led illu strations o
J
Given:
b _l.o
5
A L.O-year-o ld thinned s tand o r se cond­
growth Douglas-fir on S ite I I I .,
Average dinme te r of'
d .b eh o
tre e s prune d - - 1 0
:i.nches
.Average rate o f diame ter growtl per deo ad.!l)
2 .00 inches ( dete rmined by inc rement bori·rags
and checke d with growth cur ves in fig .. 3) ..
I ni tial pruning co s t per tree
( tabl e 1 )
• • • •
Allowance for mor tal ity
( from table 2 but reduce d for
thinned s tand )
• • • • • • • •• •
.l
I
Adju s ted co st per tree • • • •
( 100% - 15% = 85% survi val ;
251 t .85
"'
Inte r e s t rate
!
•
•
• • • • •
.,
•
30/
o o o o o o o o o o o o o o o o o o o • e
-25-
25/
15%
·301
i
I.
I
1:
C ase ��· ( Continued )
Problem: I f thi s s tand i s to be harve s ted 100 years
after pruning and if clear wood is valued at
$30 per M more than knotty 'voo d 9 what is the
expected profi t o r lo s s on c le ar wood pro
If 100 tre e s were pruned per
duoed per tree
aore9 how much profit per acre
SGlution Consul t tab le 8 . Ten-inch tree , 2 o 0 inche s growth per deoade 9 100 years . afte:r pruning9 c o s t per tree 3 01 ( interpo late be tw·een 20jl and 4o/ : $ 1 0 o l8 c o st per M of clear woo d produc e d ) . . F:�."om the s ame table note that attained d ob oh o in 100 years will be 30 . 0 inches and that 348 board feet of cl ear woo d wil have . been produc e d by pruning . $30 . 00 aS sumed premium per M for cle ar wo o <l o
1 0 . 18 c o s t per l to produce
11'9:82 profi)c per M on c l e ar wo o d produced o
=
348
One tree pro duced
$19 o82
X
o348
:
bo ar d fe et
so
$6 .90 profi t per tree .
Ei ghty-five out of 100 tree s per ac re survive 9
so
C ase Number 2 o Suppo s e that the stand in C ase Number 1 were
no t thinned and that conditions were slightly
l e s s favorable .
Aver ag e rate of di ameter growth per deo ade-1 .. 5 inche s .
Average initial c o s t per tree
Mortality allow
ce • • • • • •
• • • • • • • • • • • • • • • •
35
25%
Case Number 2 . ( Continued )
Adju sted co st per tree
Rate of interes t
o o . . . . . . . ...
· · • • • • • • • • • • • • • Q
47/ .
3%
Difference in valu e betv;een knotty
and clear wood at time of ou-bting
$25oOO.
as sumed to be
• • • • • • • • • • • • • • • •
• Q •
per l&
Problemg
What will be the expected profit or loss
the c lear wood produced if cut 100 year!!!
· after pruning?
Solutiong Same a s in Case
exeeptionsg
Number
n
1 with the .follo't'Jllng
Consult table 6 . Three percent interest;
10=inch tree 1 o5-inch growth 100 years
a.f'te:r pruning
o
Cos t per M when pruning co s ts are $1 .00 per
$88 .,57 .
tree
:;;
Cost per M when pruning costs are $0 7
tree :;: $L l e63 ( $88 o57 X o47 )
per
o
.
Consult table 8 to find that at·cained d ob 0h.,
will be 25 o0 inohe s 9 and c lear wood produc&d
\ 11 be 217 board feeto
Then proceed as in Case Nunfuer l&
$2,5 .00 as ed premium on clear wood
p:roduced o
- 41 .63 cost per M for clear wood produced
$16.63 lo ss per M on clear wood pro duced o
I
$16.63
x
6217
=
- 27-
$3 o61 los s per tree
o
Nu��o
( Continue d )
$3 o6l
x 75 surviving tre e s per ac re
$ 270 . 75 lo s s per aore e
Thi s s ame problem fieure d at 2 perce nt in
ste d of' 3 perc e nt intere s t would show a
profit of $ 2 o02 per tre e or $ 151 ,50 per aore 0
In thi s c ase 2-1/2 pe rcent i s the bre aking
·
point o
Simila:z• compari s on o a.n be fig;u.'f e d
for grow·t;h rate s 9 di ame ter 9 pruning oo s t 9
and years befor e outting 9 by c hanging only
one variable at a time .
Table
3 e.ud
5 oontrJ. ns -two addi bional
4) .
o e.ses ( Numbers
Case Number 3 i s a hypo theti c al example of a
break even pruning show in pine where the .
growth was slow and ;w·here pruning c o s t s.nd
mortal i ty we re hi gh . ·
Case Nunibe r 4 represents a rather ideal ( but
not iwpo a sible ) si·buation whe re growth o ondi=
tiona were favorable v c o s ts 1ow9 and pr emium
ror olear wo od hi gh .
CONCLUS I ONS
Thi s p ap e r has d e a l t wi th the financ i al a sp e c ts of
p runing o
Such fe ature s as s i lvicul ture 11 too l s , and meth­
ods have no t been di scu s s e d , s i nc e the·se phas e s of the
problem are a l l c o ve r e d in s everal public ati o ns o
Ra therb
the p runing i nve s tment has been e valuated to show tha
co s t of pro ducing c l e ar woo d p fo r
wi de range of co ndi tio n s .,
an r
specie s , under a
No attempt has been made to
show a :return based on unknovm future value s
The pr ning tab l e s and the di scu s s i o n o f growth
rate s 9 p runing co s ts 9 mor tal i ty
and i ntere s t rate s
vd l l s e rve as u s eful gui de s fo r fore s te r s and manage­
ment alike .,
Pruning , like 1nany o the r pha s e s of fores try9 i s
predic ated upon a fai th i n the future e
y e ar s
time o
One hundred
o:r even 50 years in thi s mo dern a ge , i s a long
Judging from the past 9 i t s eem£ to be a human
tendency to underes tima.te fu·btu•e po s sibili ti e s ,.
What
s.ppea:rs to be impo s sible or impracti ca l to day 9 tomorro'N
may become an e s tabli shed prac ti c e o
The pre s en t t:ransi ti. o n from exp l o i t ation to s c i e n­
ti fic fo re s t management i s o ne example o f: such a. change
In thi s· c as e , progre s s may have been primari ly the
re su l t of e c o nomi c expedi ency rather than i d e al i sm.
Neverthele s s
i t i ndi c ate s an incre asing empha s i s on
lo ng-range future value s 0 both e co nomic and sooi al ..
Conse quently, reali s ti c fo re sight i s one of the prime
e s s enti a l s of pruning, o f fo re s ·bry 8 o :i:' o f any o ther
effort to bui l d fo r the future o
Tab l e
5 . - - How
to use the
examples .
prunin
numbe'rs ----d
---r-----c---c-4
_!. _L s - _)
-----:--base
---------I tem -
. .
table s --hypo the ti c al
--
Knovm or e s timated variab l e s
__
_
____
___
·d-
----
1 . S peci e s
D-fir
10
2 . D .b .h . o f tre e s pruned
3 . Aver age r ate of d .b .h . growth per decade 4.
I ni ti al pruning c o s t 5.
Perc ent r i sk and 6.
pe r
P . pine
10
10
1 .5
L5 tree ( 18 ) 1 5%
morta.li t;y l o s s
C o s t p e r tree adju sted f'o J:>
D fi r
morta.l:i.ty
7.
8.
Approximate
9¢
Expected
J.arf Rate of i nte r e s -t;
pruning
3%
age a t
age at harve s t
(#9
10 .
Hol ding period
11 .
Re quired d .b .h . at harve s t
l2 o
D i fference i n value b e-
-
#8 )
40
. 50
l4o
140
150
1 00
100
100
$25
$40 1 00 1 00 20
85
75
tween c lear and kno tty
wood p e r 'M
13 . Tree s pruned p e r acre
14. Survi vlng p runed tre e s
per aore
2 5% ...30-
72
S o l1rC.:5.on.s
. r.. -=-·""""--"""""'-"'='
.,.,....
1 c
Yean; to ))X'o duc0
o l e a;:' sh0 ll
Ll=inoh
2 ,. M:i.ni:mi z a:bj,o1'J. pe:r:tod="'
cheape s t cles.:r woo d
3 " Ye e.r s 1s1 ho ldi np; pe:r·io d
I
At;·be.ine d d o'b oh c. g'l:;
L!· o
5
hs.:rva s t
Vohune o f a l ear woo d
pro du c e d pe r tree
6. Co s t per M of clee.r wood
produced
7 . Profit
or los s oxt
cl e ar wo o d produced
per M
8 . Profi t
or lo s s on
cle ar woo d pro duc ed
pe r tree ( surviving
tree s )
9 . Pro fi t or l o s s on
cle ar woo d produced
pe r a.ore
tree s }
( surviving
70
90
90
Before
Before
Bef'o:t"e
90
80
100
100
100
90
70
30
3h8
11
90
25H
25 11
50
€
L,,:t t
217
217
66.3
$10 .18 $ .1 .63
p38 o6l.
't3 . ho
of c l e ar wo o d per dol l ar o f ini ti e l prunine;
co s t y by ave rage diame te r growth per decade D and b'
pruning co s ts o ther
spe c i f i e d intere s t rate a
6 •. = = Co st
Table
( For
-·-=l
than a dol l e.:t" per tree rnul tiply fie;ure s sho>vn by
the actual
cost a )
·
D ob c h a
when
J
Ye e.1• s
e.fter
J
.E:l!1 5L �m:un�g_
Inche....s.. --.fl.,..
6
60
70
90
100
-....,_
..-=r
-....---
J
-=-
....::<'"""
runinr;
J___g _:L_
��oCfu��.sL=
28 o 28
42 o 03
4l o85
42 o62
26 o49
25 o 52
25 o40
25 o78
= - - = --
·
-
·
=
j..,E2,11,_e,§_
o
_
_
d�l�21 o7l
19 o3 0
1 7 o94
1 5 o 8h
14 o 02
13 o 07
17' ol8
12 e! l
12 . 51
17 o35
17 o37
16 o72
20 .62
3 2 .48
· 33 o 39
20 o23
20 . 28
. 20 .62
50
60
17 o 3 2
17 o 05
17 . 18
17 . 7 1
27 o39
28 o 08
50
60
70
80
90
100 .,.,.
-
Co s t of M bo ard f'eet o f c lee.r woo d
50
70
80
90
100
18 -
o= fo r -:EJ.. r s . af_
2 :o
60
70
80
90
1 00
lLt. .....,.......,
,
intere s t rate
Average di run.eter growth per de c ade at
50
80
10
e
2%
16 o OO
1 5 o58
15 o60
16 o 03
25 .78
-3 2=
1 5 ol2
l4 o34
14 . 01
14 . 05
1 .38
4
1 2 .72
1 2 . 12
1 1 .92
12 a 03
12o36
1L68
l L 02
1 0 .79
1 0 o 84
ll o l6
12 o 56
12 .41
ll a20
1 0 o 61
10 . 3 5
1 0 .-35
1 0 . 56
1 0 o43
9 .48
9 o 05
8 .9 0
8 .96
9 o21
9 o 58
8 . 61
8 . 16
8 . 02
8 o 09
8 .3 2
·
Table 6 .--( Continued )
!)n e.r. s r��: -[ } i}ercent .l_ntereet
g:IZ2 EerOAverage
diameter growth per decade at
..
d .b oh .
for
:ears af
I3 1 =��:� :c-g.:£
Co s t of
37 .93
. 37 .3 0
62 . 16 3 7 . 75 64 . 99 39 .LW.
&:; .47 42 03
29 03
.
5 0 .43 54 o42
29 .9 2 3 1 . 50 '33 .94
. ·
24
e . 38 25 21
42 . 53 · 26 67
45 .78
28 .88
' ?f")
-t-
0
53
r: .J.:&
r
r
-=l
r:: inches
·
- Ji: :L 2
board feet of clear
E:.oduced :_2�llar
M
27 .72 20.,22
2,5.88 .
18 088
25 . 26 18'.,41
25 . 66 18 .58
26 . 67
28 . 3 2 19 .27
2 0 . 40 21 . 35 15 84 20 . 28 20 19 .
i7 . Q5
17 . 67
1 7 .63
18 . 68
20 o.1 5
1 5 . 66
i5 .52
<
7· 23 . 04
15 .9 5
24 .22 16.84
26 . 13 18 . 20 42 . 0;2
5 0 .79
52 .44 91 . 72 55 .71
100 .70 61 .11 11 3 . 06 . 68 . 40
15 .02
é. 14 .,94
20 .72 15 .31
2 1 .8 2
1 6 . 08 17 . 22
23 .43
78 . 14
88 . 57
13 32 12.72
12 74
11 .55 li .49 11 . 86 1 2 56 13 26
[J
3 5 35
'
34 . 66
3 5 . 51
3 7 . 8 6
41 .33
46 . 09
27 . 23 27 . 15
40 .81
28 . 3 8 5
44 .1
30 . 57 48 .8 1 ' 33 .8 1 55 . 23 . 38 .13 25 . 79 25 .. 18 25 .,88
27.,42
29 .85
33 . 20
· 20 . 20
20 .11 21 . 00
22 ,,59
2L�- o91
28 . 0 2
22 .84 1 7 03
23 .99 17 .91
34 28
3 7 . 20 ' 26 . 01 19 42 28 .9 5 21 . 57
41 .33
32 .80 24.42
46.99
.
.
.
12 . 23
·
5
16 .99
..
1 3 .16
13 .9 2 1 5 01 wood
..
rate
65 .9 0
74.50
.
1 5 ..60 2 0 .97 1 5 .46 . . 31 . 67
2 1 . 8 1 16 .. 16
23 .54 1 7 .50
: 33 .99
37 . 53 ... 26 . 09 19 .46 68 . 40 42 . 52 29 . 61 22 . 01
- 33 -
rable
7 . - - Cos t
cos t
of c l ear wood per dollar of initial pruning
by years tci reac.h a t tained d . b. h .
fied interest ra t e ..
dollar per
( For
tree multiply figures shown by ac tual c os t . )
interest r.ate.
2 . percent
Number of years after pruning required
D . b . h.
when
.eruned
Inches
!
Inches
I
40
60
I
80
I
1.00
ost per M board fee t of clear wood
produced - dol lars
19 . 04
14 . 6 2
11. 56
28 . 29
21 . 73
17 .18
14 . 0 2
1 1 . 68
9 . 85
8 . 46
42 . 0 3
32 28
25 53:
20 . 84
1 7 . 35
. 14 . 64
12. 56
1 0 . 88
6 2 . 46
47 . 9 8
37.93
30 . 9 7
25 . 7 8
21 . 7 6
18 . 6 7
16 . 1 7
10 22
24
26
28 30
32 34 36
14 . 6 2
1 1 . 38
9 . 16
21 . 7 3
1.6 . 9 1
1. 3 . 6 1
1. 1 . 20
9 . 43
8 . 04
6 . 97
3 2 . 28
25 . 1 3
20 . 23
1 6 . 64.
14 . 0 1
11. 95
10 . 35
9 . 04
47 . 98
3 7 . 35
30 . 06
24 . 7 3
20 . 82
1 7 . 76
15 . 38
1 3 . 44
14
28
30
32
34 36
38 40
42
9 . 56
7. 72
14 . 20
1 1 . 47
9 . 48
8 . 02
6 . 88
5 . 99
21 . 10
1 7 . 05
14 . 09
11.92
1 0 . 22
8 . 90
7 . 81
6.92
3 1 . 36
2 5 . 33
20 . 94
1 7 . 71
15 . 19
1 3 . 22
11 . 61
10 . 29
18
32
34
36
38
40
42
44
46
8 , 83
7 . 05
13 . 1 2
10 . 48
8 . 61
7 . 26
' 6 . 21
5 . 40
19 . 50
15 . 58
1 2 . 80
10 . 79
9 . 23
8 . 02
7 . 06
6 , 26
28 . 9 8
23 . 15
19 . 02
16 . 03
13 . 72
11.92
10 . 48
9 . 30
I'
,I
I
d . b. h.
for trees to grow to at tained d . b . h .
18
20
22
24
26
28 30
32
I
!
A t tained
6
'
I
and by sp e.c. i =
p runing costs o ther than a
1, I
=
34
=
Table ? . --( Continued ) FJ2.
Nmnber .of ye ars . after pruning . required
ned d .b .h o :@
ror :5rcJ:1:Di2tai"
., Ii;q:I: ::Q:o::!
I'
6
M
14J-ni 'O
board feet of clear wood
23 e15 37 .,93 62 o 16
17 ..78
29 . 14 47 .. 75
14 . 06 23 . 04 37.,75
18 .81 3 0 .82
15 .66 25 .66
13 .21 2l o65
ll o.34 18 e58 16 09 8 .. 58 47 75
""'l)
P!f
.,;:;
ICI
,.,<!2.U
..
10l o81 · 28 .; 12 · 50 o79 9l o73 1 65 o70
78 o21 2l o60 .39 .02 70 .46 1 27 &28 61 .84 17o08 30 o85 5.? $71 100.64
82 .. 15
25 o 18 45 u4B
40., 58
20 o97 37 .87 6So40
2 e03
17 .69 3 1 . 9 5 57 .,7 2
3 5 eL,.7
1 5 o l8 27 e42 49 . 53
,30 .43
23 o75 42o9 0
26 o:;6
·
·
37. 16
29 o92
24 e61
20 .72
17 .67
15 .31
13 o38 78 . 21 21 o60
60 88 16 .81
49 o00 13 o54
40 o.31
3.3 ..94
28 o95
25 ,. 07
21 .91
39 o02
3 0 o 37
:?4 o45
20 . 1 1
16 .93
14 .1 -t.
12 .51
70 .46
5L o 85
44 el5
3 6 o3 1
30 e 57 26 . 08
22 .59
19 .74
9 . 05 3 1 .,21
15 .38 25 .. 21
12 .,72 20 ..84
10 ..76 17 .. 63 9 .22 15 ., 12 8 . 03 13 o16 1 1 . 55
10 .24
5l ol3 llhl2
4l o29 11 ..41
34 o 13
28 o8S
24 ..76
21 .. 55 18 .,93 16 .78 25 o51
20 .,60
17 . 03
14 .41 12 .35
1 0 .75
46 .,06
37 e20
3 0 o75
26 .. 01
22 .. 31
19 .42
17. 05
15 oll
17 .78 29 o l4
13 .84 2 2 o68
ll ol4 18 . 26
15"" 02
12 o6/+
1 0 . 78
9 .34 10 e74
IIQ:J_qo_:]_.��I)oo
1oo
8o
Co st ner
t== ::
11 .62 9 o39
>::p:����€}yt���·�:�S;.i?.!i!__,.
rcent in1?.e_r��-��[
.
17 o60 28 .84 47 24 13 ., 05 23 o 57 42 . 56
14 . 06 23 . o4 37.,73
1 0 .42 18 8 2 33 ..99
15 .46 27 . 93
1 1 5 5 18 .92 3 1 . 00
.
.
.
9 .73 15 .95 26 . 13
8 .33 13 . 66 22 .37
19 .42
7 . 24 11 .86
17 · 09 1 0 .43
15 . 16 9 . 26
13 .o4 23 .54
1 1 . 16 20 . 15
9 .69
17 . 0
15 . 0
-35 -
1 27., 2 8
99 .,07
79 ..75
6 5 . 60
55.23
47 .1 1 40 ..81 .35. 66
8] ., 2 0
67 ..20
55 .. 55
46 .99
40 ..29
3 5 ..07
30 ..8 0
27 o30
76 .. 88
61 ..41 50 .45 42o52
3 6 . 40
31
.. 61
27 .81
13 .66 24.67
,I
. ,
'I
·I
l
·.
I
!
I
\t
1,1
!I
I
r
Table 8A .--Pruning c o st per thousand board feet of c le ar
wood produced - Scribner rule . D .b .h. of tree
.when pruned 6 inche s , intere st rate ·
percent .
---
D
E
]
Average
growth
per
dec ade
Inches
1 .. 0
1 ..5
2 .. 0
Approx .
number
rings
_Rer inch
Years
after
prunin
23
15
ll
120
Attained
d .b .,h .
Inches
18 .0
Growth
c le ar wood
Board
116
80
90
100
18 .,0
19 .. 5
21 .,0
116
60
70
80
90
100
18 . 0
20 .0
22 . 0
21J. ., o
151
191
234
26. 0
142 170
116 28 1
2 .5
9
50
60
70
80
90
100
18 . 5
21 .0
23 .. 5
26. 0
28 . 5
3 1 o0
124
170
223
281
346
417
3 ..0
1
4o
. so
18 . 0
21 .0
116
170
234
·
3 o6
388
479
60
70
80
90
100
24 c. O
'i!l . O
;o .. o
33 . 0
6 .. 0
2,79_
(}rowth o f clear wood i s . growth on the . fi r s t l foot log .
Top d .i .b . of log e quals .so d .b .h . Diameter o f knotty
core as sumed to b e · 1 .5 inches larger than diameter of log
at time of pruning . Minimum attained d .b .h . considered
is 17 .9 inche s , which will yield a. log whose diameter i s
6 inche s greater than dia.:ineter o f knotty oore .
- 36-
Table 8A .--( Continued )
=
.... ...-....-.--......__
.
•
t
ini tial
Dollars . .
33 o3 8
66o76
13 o 00 12 o43
13 o89 24.,86 26 oOO 27 o79
7 o 59
7 o46
1 5 c-17
14o92 7 . 89 8 o 41
15 o 78
16 ,81 5 o 5lJ.
-...,.,_,
100 ol4
-.:0--
- --....-..--
Pruning cost per M bo ard feet, when
tre l:,l_'Lcen e. i s
co t
' 80
0
0
c..__ _
__,?., : :1 : ::._
-Q
_
----·---
133 Q 52
1 00
...o ...._
__....-.
-
- .:::0 -....0
1 66 o90
37 o3 0
49 .73
5l o99 55 o!)8
62 .,16
15 o 1 0 2 2 o76 22 o38 22 ,65 23 o66 25 e22 3 0 e34
29 84
30 o20
31 o 55
33 o62
37 ..93
37 <>3 0
37 o 7 5 39 .,44 42 o03 ll o 09
l0 o35
16e63
1 5 o53
22 ., 18 27 7 2
5 o 13
5 .,33
5 .66 l0 o26 10 o67 ll o33
15 o40 l6.,oo 16. 99 l�-o63
4o 04
3 o76
3 o 68
3 ..7 2 3 .85
4.
9 o 26 8 o09
7 .52
7 .36
7 o 43 7 o 71 8 o 16 13 o89
12o l3
ll o28
ll o 05
7 .55
5 .. 18
5 05
o
l O o lO 38 o99 4l o68 15 o l6
ll o l 5
1l o 56 12 .24
-37-
o
. 20 7 0
..
20 .21
20 o 53
21 .34
22 .1)6 18 o52
16 cl3
15 o 04 14o73
l4o86 1 5 .42
l€.a2
64.,99
69 ..47
..
25 .. 88
25 .. 26
25 .. 66
26 .67
28 ;32
23 ol5 20 22
.,
18 .,80
18 41
1B o.5B
..
19 o 'Z/
2o 1+o
..
I
tl
II
·I
Table 8B o - PruninG co s t p e r thous and bo ard f e e t o f c l e ar
woo d produce d - S cribner rule . D .b oh o o f tree
whe n prune d 9 10 inche s ; intere s t rate �� pe rc ent o
Average
.gro•v:th
per
de cade
Approx .
number
rings
u e r inch
-
Year s
af·ter
,_Qruning
Attained
d ob o h o.
Inche s
0
Growth
}}.2,ar:�
1 ., 0
23
L5
15 18 3 217 11 194
21-t.l
--­
161
293
348
161
9
217
279
348
423
504
Growth o f c l e ar woo d i s growth on the fi r s t 16-foo t log .
Top d o i ob o o f log e qual s aBO d ob oh o Diameter o f kno tty
core as sume d to be 2 . 0 inche s larger than di ame te r of l og
at Jci:ms of pruning o Minimum attained c1 .b oh o considere d i s
22 .5 i nche s 9 which wi ll yi e l d a log who se diame ter i s 8
i nche s ' gre ate r than di amete r o f lmo tty core o . ·
\
-38 ­
,.
Tab l e 8B . - ( Continued )
��
..
-----
---->1> --rn:ll '"'
-
Pruning c o s t per M b o ard f'ee t p whe n ini -bi al
is
in c ents
tree
co
=
:J: )g�
:2:�-:-::r=E:=
Do l lars
--
108 .83
136 o04
3 0 . 26 3 2 .65 40 .34
43 .54
50 oL 3 5J+e ·2
1 1 .61
l L 97
12 . 60
13 . 58 17 . 2
17 . 95
18 .90 20 . 3 6 23 .22
23 o9l.J. 25 .20 27 o l5
29 . 03
29 .92
3 1 .5 0
3 3 .94
8 . 54
8 . 11
12 .81
12 . 17
12 . 11
12 .43
1 3 . 09
17 . os
1 6 . 22
16 . 15
16 . 58
17 .46
18 .74
2L ,35
20 . 28
20 .19
20 . 72 21 82 23 .43 10 . 67
9 . 50
9 e 01
8 .96
9 . 19
9 .65
1 0 .33
14 . 2 2
17 .78 15 . 84 15 . 02
42
27 . 21
5
1 0 . 09
10 .88
20 . 17 21 . 77
5 .8 1 5 .98
6 ,3 0 6 .79
h . 27
4.o6
4 . o4
4 . 14
1+ .3 6
4 .69
3 .56
3 17 3 .00
2 . 99
3 . 06
3 . 22
,
_ 3 ..
.•
8 . 08
8 . 29
8 .73
9 .37
7 .11
6 . 34 6 . 01
5 .98
6 . 12
6 e43
q,.s9
13 1 . 62
14 .06
12 .67
1 2 . 02
1 1 . 95
1 2 . 25
12 .86
__ _
fu'@___
14.94
o
15 . 3 1
1 6 08 1] . 22____,
I
'I
[
'I
,,
I
I
,}
':1l
'l
.-39 -
Table 8 C
=Pruning c o s t per thou s and board fee t of c l ear
of tre.e .
· wood pro du c ed - Scribner rul e .
inche s ; intere s t rate
percent .
when
D ob oh o
pruned11 14
Awre.ge
I
J
g;rovrth
per
deee.de
Approx .
numbe r
rings
per inch
Imhes
Years
after
pruninr;
11
Inche
s'
'
Board feet
--=-
-
i o
27 o0
204
90
27 o 5
29 . 0
217
258
28 o0
231
70
80
90
3 0 o0
100
32o0
34oO
346
409
60
29 .. 0
31 o 5
258
3.3 0
70
80
34oO
lOO
39 o0
50
60
.29 . 0
:?2 o0
90
286
t586 3 6o 5
70
35 e0
90
100
41 . 0
44oO
258
36 . 0
80
Gro
Growth
clear
woo d
-
d eb oh o
-
100
2 .. 0
Attaine d
u o q•-•
346
442
5l.JB
66:;
78'1_
. . ..__
h o f clear woo d i s growth on the fi r s t 16-foo t log o
Dieme ter or knotty
Top doi cb o of log e qual s o80 d .b .h o
· of log
core assumed to be 2 o 5 inc he s larger than diruneter
at tim.e o f pruning . Minimum attaip.ed. d ab ch o cons i dered i s.
27 . 1 inohe s 11 which wi ll yie ld a l og who s e diameter i s 8
ineoos greater than di ame te r of lalotty core .
'
T able 8 C . - ( Continued )
-----
:
Pruning o o s t p r M board fe et, when ini tia.l
e .• i n oents p _i s
co s t e r
:___gJ[:
I
-=li<L :: ]
6o
__
I:
I �L.::
8:o
Dollars
-
--
121 o47 24.29
48 .59
7 2 .88 97 ol8
8 .51
9 . 16
17 . 01
18 . 3 1
25 . 5 2
27 . 7
34 . 02
3 6 62
1
4 .88
5 .. o .
5 . 33
5 . 78 9 .,7 5
1 0 08 l O Q 67 11 .55 1Lh63
1 5 . 13
16.oo
17 . 33
19 . 5 0
20 . 17 21 .34
23 . 1
21+ .. 38
0
26o67 28 o88
3 .41 3 .41
3 .53
3 . 74
4 . 03 6 . 82
6 c8 3
7 . 05
7 .47
8 o 06 1 0 . 23
13 . 61-J.
13 .66
14 . 1 0
1L,. • 94
16 . 12
17 .. 05
17 .0'7 17 .,63
18 ,68
20.15 2 .66
2 . 54
5 33
2 .63 2 .78 2 · 00
5 .26
5 o57 1 0 66 1 0 . 18 1 0 . 19
1 0 . 53
1 1 . 14
12 .01
13 3 2
12o72
12o74
13 16
13 .92
12_ 01
2 . 55
10o24
1 0 o 58
11 . 21 12 . 09
5 <> 09
5 . 10
7 o99
7 .63 7 . 64
6 . oo
8 . 35
9 .01 ·
..
7 o9 0
45
..
·53
..
78
25 .21
.•
..
..
Table BD .--Pruning c o s t per thous and bo ard fee t o f c le ar
woo d produc e d - S c ribner rule .. D .b &h e or · tree
perc ent .
when p rune d , 18 inche s ; inter e s t rate
I
i
Average
g,rowth
per
dis c a de
.
Approx o
number
rings
per inch
..
Ye ar s
after
pruning:
Inche s
Attaine d
d .b .h .
· Inches
Growth
clear · woo d
Board feet ·
· -
-
l eO
23
145
32 5
265
1 $5 15
100 33 .. 0
28 1
2.0
11
70
80 90
100
32o0
34 .0
:36.0
38 .o
381
452
250 3 13
2.5
9
60
70
eo
90
100
3,3 .0
3 5 ., 5
38 .0
4o .s
43 ,0
281
363
452
548
649
, .. o
7
so
60 70 .80 90
100
33 oO
281
36.0
39 .0
42 . 0
45 . o
48 . o
381
49 0 608
73 5
871
Growth of clear woo d i s growth on the fir s t 16-f'oo t l og .,
Top d: ., i .,b ., o f log e quals oBO d. •b . h . Diameter o f kno tty
core as sur ed to b e 3 o5 inche s larger than diameter of log
at time of pruning . Minimum attaine d d .b .h ., considered
is 32.4. inche s 9 whic h will yield a log who s e Q.i e.me ter i s
8 inche s gre ate r than dirumeter o f knotty co re .
-42-
Table 8D . --( Continued ) ::§£
Pruning c o s t per M board feet , when initi al
c o st _Eer tre e 2 i n c ents i s
=---20=
I
o
I
6o
I · : 8o
1 00 .
:
Doll ars
1 08 o35
135 LJ4
25 .. 22
33 .62
42 03
13 o52
13 o82
14 .53
15.68
18 . 02
18 .43
19 . 38
20 .90
22 ..53
23 . o4
24o22
26 .13
9 40
9 -31
9 - 57
12 .53
12 o42
12 .76
15 .66
1 5 o52
15 .95 27 o 09
54 .18
8 1 . 26
8 . 41
16.81
4.51
4 . 61 4o84
5 . 23
9 01
9 22
9 o69
10 .45
.
..
3 .,13
3 .10
3 .. 19
. . 3 .37
3 . 64 6.26
.6 .21
6 38
6 .74 .
7 28
2 .45
2 .3 1
2 .3 0
2 .37
2 . 51
2 .71
4 .89
4 .62
4 60
4.74
5 .02
5 .42
.
.
.
.
. 10 . 10
10 .92
7 -34
6 .93
6 .8 9
7 . 12
7 .54
8 .14
-h3-
f
1}1..47 .
l4 o 56
9 . 78
9 . 24
9 . 19
9 . 49
10 . 05
10 .85
.
.
.
..
-16.84
18 .20
12 .23
11 $ 5
11 o 9
11 .86
12 . 56
13 .56
.
.
LITERATURE CITED (1)
.
Briegleb , P . A .
1945 o C alculating the growth o f ponderos a pine
forests o U .s .D .A . ,Fore s t S e rvice 11 Portland, . .
Orego n . 60 pp . i llus .
{ 2)
1950P Propo s e d
r e s e arch priorLti e s for a regional
program of fores t management . Paper pre­
pared for the Progre.m ·conference of the
Pac ific Nor, thwe s t Fo re st and Range Experi­
ment S tation9 J anuary 30-February 3 , 1950 .
6 PP c . ( Proce s s e d )
(3)
Douglas-fir S eoond growth Management Committee .
1947 . 'Management o f s econd-growth fore s ·l;;s of the
Dougl as-fir r e gion·. Portland9 Oregon ,
PNWF&RES . 151 pp . illus .
( 4)
I s aac !l L . A .
( 5)
Jor gensen , G .
1949 o Memorandum to regional for e s te r. 11 R 611 S
S tand Improvement$ General 13 PP e April 79
1949 o ( Typewritten copy )
1949 .
( 6 ) Kachin,
1940 .,
( 7)
-·
1942 ..
Better Douglas-fir fore sts from better s e ed .
University o f Washington Pre s s , Seattl e ,
Wash . 64 pp . illu s .
T.
' Natural pruning i n second-growth Douglas-fir .
PNwVF&RES Res e arch Note No . 3 1 November 309
1940 .
Prunln'g and spot
Washington Gulch
Whi tman N ati onal
illus ., March 4,
thinning time s tu dy .on the
s tand improvement pro j e c t s
Fore s t . PNVIF&RES . 1 6 pp a
1942 . ( Typevrrit en repor t )
(8)
Mattoon9 W. R ..
1942 e P:runing southern pine s . U . S . Dep t . Ag:r .
Farmers ' Bul . 1892, 34 PP • i l lus ..
(9)
Meyer, W., Ho
1934 ., Growth i n . selectively out ponde rosa pine
fore sts of the Paci fi c Northwe s t . U '" s ..
Dep t . qf' Agr . T ech . Bul . 407 1) 64 pp . i llus ..
( 10 )
Munger9 T . T ..
191!4 .. Cost and benefi ts of s tand improvement .,
PNVVF&RES .. July 1942 P Revi s e d Decembe r 2 9
1944 . ( Typewri tten r eport )
( 1 1 ) Shaw, E $ W .,
1949 .. Report on the 1949 remeasureme nt of Olympi c
P .S .P Y s 11-14 near Kugel C re ek ¢ PNVW&RES
July 14P 1949 .. 9 PP
( TypeviTi tten report )
( 12)
-e
( 13 )
1949 "
Pruning of Douglas-fir at the \Toight Creek
Exp erinental Fore s t . Puget S ound Re search
Cente r , PNWF&RES . 6 pp . ( Typewritten report )
1950 .
S tand improvement r e s e arch in the Douglas-fir
region. Pape r ,prepared fo r the Program Con­
ferenc e 9 PNVlF&RES 9 January 3 0-F ebruary 3 9
1950 , . 10 PP • ( Pro c e s s e d )
·
( 14 )
S taebler" G . R.,
1949 . Growth of Douglas-fi r by c rown c la s s .,
P1 W&RES 9 ( Typewri tten report )
·
( 15)
Worthingto n , N ..P .,
1950.. Growth fo llowing expe rimental thinning o f
s ec ond-growth Dougl a s-fi r of OlJ pic
Peninsul a . PNV'IF&RES
Apri l 1950 o
( Typewri tten repor t )
e
What -often happens whe
n trees are not
pruned.
This 18-.inoh_, f'as t grow.i.ng
Douglas-fir tree on the
McCleary Elcperi­
mentaJ. Forest is typical
of many of the
rough dominants in the
stand.
Uhless it
is removed in thin
ning or artifi cially
pruned, it will probab
ly continue to
produce nothing but kno
tty, low grade
material for 5o to 100
years .
· '
'
P R U N I N G A Y O U N G S TA N D
bF
PON D E ROSA P I N E