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· ·· ·
DAVID BRUCE
DONALD J.
MARS
DONALD L
'
fABLE
PROGRAM
1
OFIT
DOUGLAS-FIR MANAGED
YIELD
SITE INOEX=I40,U
THE CONTROL CARD SPECIFIES THAT
DIAMETER OF THE MERCHANTAOLE PART OF TH£ STANO
THE MihiMUH HERCHANTA8LE OBH IS
6,00 INCH�S,
I ABLES
J I �0-YEAR
AT THE
BASIS)
FIRST POSSI&LE CO�HERCIAL THINNING
IS
IJ,OO
INCHES,
THE STANO HAS NOT HAO A
PRECOMHERCIAL THINNING,
THE TMINhiNG INTERVAL IS
10 VEARS,
NUMBER OF COMMERCIAl THINNINGS=
2o
TOTAl AGE AT HARVEST=
60 'fEARS,
150o00 PER THOUSAND BOARD FEET SCRIO�ER,
120,00 PER THOUSAND BOARD FEEl SCRIBNER,
• 060 0 •
HARVEST STUMPAGE=�
THINNING STUMPAGE=$
DISCOUNT RA"fE=
OON
'
TOTAL COOOH
AGE
HEIGHT
YEARS
FEET
STANO
COMPONENT
I�EAN
OOH
INCHES
HE
�'lt
G
HEAN
�552
II24
1764
4841
4103
1367
4054
3614
1204
17484
16612
5533
8916
6916
2967
134.2
1 71 7
I �o, 6
46.9
167.9
21.3
VOL G�OWTH
SU8HERCH MORT
4.62
01266
3.00
23,12
TOTAL OEFORE
9.27
<;,05
,4687
,1393
15.71
3,56
33,51
25.54
I 0,07
9.19
10.48
9o30
,5535
• 4602
.5989
.4717
16.6 4
15,32
20,54
I5,0l,
•
2673
•
•
•
lj;\
cu Fl
4626
J�;�Ni�4 Y
6-INCH
SCRio Y
�
ACRE
6� I, 5 171.4
292
l325
w
5291
245
'•856
157
25264
222
17705
336.9 157.9
69.0
9.6
34.03 •
33.30
34o30 'li'
37!,50 ..
5046
13"3
37 03
39'>8
4699
1234
7!465
3€22
25042
6��8
18703
18926
17705
4226
IJ<o77
13<,77
267,9 148.3
87,6 40.3
160.3 108.0
249.2 117.6
7163
6414
271 I
635'3
59071
2438
11n21
30575
II 872
20672
20672
7195
226, I
195.2
221.9 87.3
20I.. a 171' 6
21 '5
3.2
•
.
8.49
4o98
.1354
3, 43
25,34 "
2861
163
I o2
121
SUONERGH
I 2,49
5o21
.8503
• 14 80
32.94
... 0 2
3.8o74 -'J.
27. 16 "
66.. 6
86
6349
58
37827
73
30349
MERCHANTABLE
13' 09
.9341
36,39
16,96 ,.
6560
6 290
H7Se,
303'>9
180.3 168.4
HARVEST
13.09
.9341
36o39
38o96
6560
6290
11754
30349
160.3 1 6 6
I00 23
9270
9270
9181
80'29
8729
50345
49626
49626
J7541o
37544
17544
286.5
255.6
402.1 255.6
VOL GROWTH
SUOHERCH i'IORT
TOTAL
BEFORE
W.
47o5
$
.
2322
504
.
SUM GROSS
GRANO
1039
402.1 140.6
r3'>.2 1,6,9
267.9 93.9
50�.7 124.7
8 ,oI
II0. I
1483
283
8916
2967
5949
5949
SUM GROSS
SUH t!ERCH
SUM OF CUT
60
2656
50 7
16612
�533
II079
119 50
HERCH lEAVE
TOTAL lEAVE:
10.20
I0,19
I0,21
6.66
II0, I
1337
3614
I 20 4
2409
2650
,3502
,3497
o35 Ot•
• 24 71
60
1337
356
4103
1367
zn6
1474
6 ,O I
8,0 I
8.02
6,73
SUM HERCH
SUN Of CUT
1�37
356
29. 14
29. 13
29, I�
27., 85
7o56
3,I 2
TOTAL lEAVE
PRICE
639.0 171.7
236.6 30,9
.2667
,13 OJ
HERCH LEAVE
CUM
PRICE
6916
7.02
4.69
SUOHERCH
DISC
PRICE
1148'>
872
TOTAL BEfORE
HERCHANTAOLE
CUT
CURRENT
ACRE
SO FT
4054
�40
73.7
91.6
I'ER
PEll
'•641
7J6
36
46
]j
TREES
28.2 0 ..
2"3o92 �
7.00
CUT
ACR!!
26,15
FIRST POSS
•
�-INCH
cu fT
PEP
7.52
73.5
MERCHANTABLE
'40LUHE
sa FT
VOL/G
RATIO
35,9
SUOHERCH
lZ
VOL
CU FT
$
$
,.
6.�
.4
TOTALS
SUM GROSS
�ERCH
SUH OF CUT
SUH
ll
?_!
Basal
Board
"
10.80
area.
feet.
",-.��,
-"\--...
Abstract
DFIT simulates the yields of managed Douglas-fir
stands.
Management practices that can be simulated
include planting,
thinning,
precommercial thinning,
and fertilization.
commercial
Equations used in DFIT
describe growth of natural stands,
estimate the volume
increment of thinned stands and plantations,
predict amount and timing of mortality.
and
Changes in
most of these estimates can be made by the user without
destroying consistency of other estimates.
KEYWORDS:
Computer programs,
thinning
increment estimates
(forest),
(stand),
growing stock
(tree),
yield
(-increment/
yield.
Metric Equivalents
1 inch
1 foot
1 square foot
1 cubic foot
1 square foot per acre
1 cubic foot per acre
=
2.540 centimeters
'0.3048 meter
0,09290 square meter
0,02832 cubic meter
0.2296 square meter per hectare
0.06997 cubic meter per hectare
�,�
, .
Contents
Page
INTRODUCTION
1
S
YIELD TABLE
Explanation of DFIT Output.
Effect of Varying Assumptions
2
2
4
CONTROL CARDS , . , .
Required Controls
Cutting Age Controls
Other Optional Controls
6
6
6
4
8
8
9
FUNCTION LIST. . . . . . . .
Natural Stands. . , . .
Stand Density Relations
Growth Functions
Volume Functions
Submerchantable Trees and Mortality
Precommercial Thinning Adjustments
Commercial Thinning .
Fertilizer Adjustment
Growth Adjustment
10
11
13
13
14
14
15
S
CHANGING FUNCTION
15
APPENDIX . . . ,
Symbols , ,
Subscripts
17
17
17
1-
Introduction
1
I
!I
Estimates of yields of managed Douglas-fir stands were prepared in
1972. !/ Management practices included commercial thinnings, precommercial
thinning , and fertilization. These estimates have since4been used for
several purposes both in and outside the Forest Service. Most users re­
quested more details concerning the stands than those supplied by the
original estimates. These requests led to the development of a method of
simulating stand growth and a computer program DFIT (Douglas-fir Interim
Tables) to tabulate the results of the simulation.
The basic components of DFIT are: (l) equations describing the develop­
ment of natural stands, (2) thinning guides�/ based on Reineke's stand
density index, �/ (3) equations describing the total cubic-foot increment of
thinned stands and plantations, (4) equations predicting amount and timing
of mortality in natural stands, (5) a method for describing stand components
at intervals without the direct use of stand and stock tables , and (6) many
assumptions about management practices and their effects on stand develop­
ment. These assumptions are based on careful study of currently available
results of Douglas-fir thinning studies. They have been balanced against
growth of natural stands and have been checked for internal compatibility
and consistency.i/
Since no stands in the Pacific Northwest have been thinned regularly
for 60 to 80 years, the yields estimated by the simulator are extrapolated
far beyond the available data base. The extrapolations seem reasonable to
the authors and several users, but this is no demonstration of their
validity. The growth rates and other factors affecting yieldwill need
revision when results of a current cooperative study of managed Douglas-fir
;.
The program is written so that changes in most
yields are published.
estimates can he made without destroying the consistency of other estimates.
Estimates are for net forest acres and gross volume yields. Appropriate
deductions should be made for roads and other nonforested areas and for
breakage during harvesting.
___
DFIT was made as flexible as possible, but it was necessary to control
some relations by rather rigid assumptions. Within limits DFIT allows the
user much more freedom to test and observe probable results of different
management regimes than do many other stand growth simulators.
This paper explains how to use the simulator and describes its operation
in enough detail that the reader can make his own adjustments.
The paper
starts with a description of program output and several examples followed
by a description of how to control the program and some of the limits that
should be observed. The function list displays operating assumptions and
suggests how some may be modified to test other assumptions.
Finally, there
is a brief discussion of how to change some functions. Symbols and abbrevia­
tions are defined in the appendix. Arrangements for obtaining program decks
can be made with Project 1301 or Project 1207, Pacific Northwest Forest and
Range Experiment Station. For Forest Service users, DFIT is available on
the UNIVAC at Fort Collins, Colorado.
_
1/ Bruce, David, and D. L. Reukema. Douglas-fir managed yield tables. Unpublished
1972 report on file at Pacific Northwest Forest and Range Experiment Station, Portland,
Oreg.
�/ Reukema, Donald L. 1975. Guidelines for precommercial thinning of Douglas-fir.
USDA For. Serv. Gen. Tech. Rep. PNW-30, 10 p., illus. Pac. Northwest For. and Range
Exp. Stn., Portland, Oreg.
11 Reineke, L. H. 1933. Perfecting a stand-density index for even-aged forests.
J. Agric. Res. 46 ( 7 ) :627-638, illus.
if Reukema, Donald L., and David Bruce. 1977. Effects of thinning on yield of
Douglas-fir:
Concepts and some estimates obtained by simulation. USDA For. Serv.
Gen. Tech. Rep. PNW-58. Pac. Northwest For. and Range Exp. Stn., Portland, Oreg.
�-
--��---
�-----
Yield Tables
EXPLANATION OF DFIT OUTPUT
Each table produced by DFIT starts with a list of the variables specified
by the user and some of the assumptions included in the run. The list length
varies with the number of optional controls used.
The first example illustrates some simple assumptions (table 1, fold out
front cover so table can be followad as text is read; other tables are in the
appendix) . In this example, a fully stocked natural stand of Douglas-fir on
site 140 is to be commercially thinned when its merchantable trees average 8
inches in diameter. In such a natural stand, trees larger than 6 inches are
considered merchantable. This commercial thinning will be followed by a
thinning 10 years later and a harvest cut at age 60. A financial summary is
included, discounting stumpage values at 6 percent to date of first commercial
thinning. Harvest stumpage is $150 per thousand board feet, Scribner scale,
and thinning stumpage $120. A summary table and a comparison with a natural
unthinned stand are requested. There is no implication that this is a
recommended or optimal schedule--it was chosen to illustrate the main features
of the output in as small a space as possible. The information at the head
of table 1 lists the assumptions:
the site index (100-year basis) , the average
diameter of the merchantable part of the stand at first possible commercial
thinning (CT) , the minimum diameter limit for merchantable trees, whether
the stand was precommercially thinned, the thinning interval (10 years) ,
thinnings (two) , the harvest age (60 years) , and the financial details.
Throughout the table average numbers are stated with sufficient digits
to allow checks of consistency. The extra digits do not imply accuracy an�--.
should be dropped when comparisons with other schedules are made. Total age
is given in years for each date of thinning or harvest. Average height of
dominants and codominants is stated in feet.
Mean d.b.h. for tree of average
basal area is given in inches. Mean G is the basal area of the average tree
in square feet. Volume of the tree of mean basal area is in cubic feet and
includes tip and stump. The volume-basal area ratio has a dimension of feet.
Volumes per acre are given in table 1 as total cubic feet including tip
and stump (CVT) , cubic-foot volume above a stump that is 1 percent of total
height to a 4-inch d. i.b. limit (CV4) , International 1/4-inch rule to a
5-inch d.i.b. limit (IV5) , and Scribner formula to a 6-inch top (SV6) .
Both
board-foot estimates are based on 16-foot logs scaled to the nearest one-tenth
inch. It is not possible to accurately estimate Scribner board feet for small
trees when 32- or 40-foot logs are scaled to the next lower inch.
A crude
approximation can be obtained by multiplying stated Scribner by 80 percent.
In table 1 the number of trees per acre is stated.
"G per acre" is
basal area per acre in square feet. Current price is listed to the nearest
dollar based on the given stumpage and the estimated Scribner volume thinned
or available for harvest at the given age. Discounted price is the current
price discounted to date of first commercial thinning. Cumulated price is
the sum of all previous thinning values and the harvest value of the current
merchantable stand discounted to date of first commercial thinning.
In the third column of the tables the labels identify the stand component
described in each line. The label "first poss" is followed by a description
of the stand at the fractional year when it first reaches the specified
minimum diameter for CT. The stand completes its growth for that year before•--·
'
�h
it is broken down into the components that can be recognized at the time of
the first CT.
The label "total before" precedes a description of the stand component
that includes trees below the merchantable d.b.h. limit which are identified
2
as "submerch." It is assumed that practically all of these trees will die
before reaching merchantable size. Table l also includes a "merchantable"
label which is followed by the description of the stand component that can
be thinned or projected forward in time. "Cut" is tfJ.e part of the merchant­
able stand removed in thinning,
"Merch leave" is the part of the merchant­
able stand left after thinning. "Total leave" is the total living stand
immediately after thinning.
l
I
The first summary line ("sum gross") shows gross volume per acre, the
sum of the volume of living trees at a given date plus the volume of all
trees previously cut or dead. The sum of the merchantable volume ("sum
merch") is the present merchantable volume plus all volume previous�y cut.
The sum of the cut is the total cut up to and including the current thinning.
The mean diameter of all cut trees to date is stated in this line, as is the
number of cut trees.
The summaries also show the basal area of trees whose
volume is reported.
"Vol growth" is the estimated cubic-foot increment for the period be­
tween thinnings. It is one of the three elements that make it possible
to simulate growth of the stand between dates of cutting. The other
elements are changes in dominant and codominant height and number of trees.
"
Sub merch mortality" is the mortality occurring since the last thinning.
The number of dead submerchantable trees starts the report on second cut
and is used in the calculation of stand components for the current date.
It is assumed that no merchantable trees die in the interval except those
that can be salvaged with the current cut.
The subsequent lines for the stand at the time of the second cut at
age 46 correspond to those for the stand at the time of the first cut. The
r·
program will report 19 dates of thinning.
For the final cut the table includes the first three lines of a thinning
report and then repeats the "merchantable" part as the harvest. A final
summary of gross, merchantable, and cut volumes completes the main report,
A summary table is printed after the main table, if requested. It
repeats the per-acre data for the total and merchantable live stand before
each cut (table lA),
If requested, a report (table lA) is printed showing development of
natural stands growing on the same site and at the ages of the preceding
table. Most of the column headings and line captions for table lA are
the same as in table 1.
No data are reported until the natural stand
reaches the specified merchantable size. Stumpage values are discounted
to age of first commercial thinning in the previously described managed
stand .
This part of table lA is mucn the same as a table that could be
derived from Technical Bulletin 201Q/ except that it describes the mortality
occurring between two ages. These dying trees (table lA) are assigned sizes
and are separated into submerchantable mortality and merchantable mortality.
£/McArdle, Richard E., Walter H. Meyer, and Donald Bruce. 1949.
The yield of
Douglas-fir in the Pacific Northwest. U. S. Dep, Agric. Tech. Bull. 201 (rev.), 74 p.,
ill us.
3
EFFECT OF VARYING ASSUMPTIONS
Changing controls will change the estimates. If the average size of
the merchantable stand is increased from 8 to 10 inches, the minimum mer­
chantable diameter at each cut and the age at first possible thinning are
increased. These changes affect most parts of the consequent estimates
(table 2).
The date of the first commercial thinning (table 3) is deferred with
controls changed back to an 8-inch average merchantable stand. This change
increases tree size and yield at first commercial thinning but reduces yield
at harvest date.
Assuming the stand was precommercially thinned (PCT) makes even greater
changes in the estimates (table 4) .
In DFIT it is assumed that all trees
left after PCT reach the specified minimum merchantable diameter. Any trees
that might die later are included in the next thinning, so the table includes
no accounting for mortality, shortening the table considerably. If they are
requested, the summary table and the natural stand table contain the same
information as in table lA.
Another variation in assumptions is that the thinning cycle is controlled
by the time the stand makes a specific amount of height growth (table 5) .
The program calculates the fractional year for completion of this growth
and goes to the nearest full year.
The effect of fertilizing with 200 pounds of nitrogen per acre can be
simulated. Either fertilizing at time of CT or at certain a:ges after first
CT can be specified (table 6) . PCT is assumed to improve the site, and
growth resulting from fertilization will be calculated on the basis of thiB
improved site.
·
Stands with PCT can also have delayed CT (table 7) .
Plantation growth can be simulated by setting PCT age at 2 years
(table 8). If this is done, the implicit assumption is that the stand does
not suffer losses conwon in most Douglas-fir plantations. The example is
listed for comparison with the next example, not as an illustration of
average plantation yields.
A user option can increase growth for the life of the tree and simulate
genetically superior trees grown in plantations (table 9) . This is one
example of four user supplied estimates of gains or losses in growth. This
example assumes a change in growth that affects the entire life of the
stand but not the corresponding natural stand. Other assumptions change
growth from PCT to harvest and from first CT to harvest. A fourth assumption
changes growth rate of natural stands as well as managed stands.
Control Cards
Usually a single control card will produce a table for one set of
assumptions. Extra cards are used only when ages at time of thinning or
fertilizing are specified.
(1) site index (100-year basis), (2) a m1n1Required assumptions are:
mum merchantable diameter or a mean diameter for first possible CT , (3)
interval between CT's, and (4) number of CT's.
A set of controls of cutting ages is included that makes possible
complete specification of the schedule in several ways.
4
Optional assumptions are:
(l) PCT, (2) fertilization, (3) user supplied
percentage change in growth , (4) diameter ratio of cut component to merchant­
able stand, (5) financial report, (6) summary table, and (7) natural stand
table.
The rules for setting up control cards follow. Dots on the line under
the headings indicate location,of implied decimals (fig. 1) .
I
�
Figure 1.--Coding form, DFIT control card 1.
Requested
by
Statement
No.
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• ••• • ••••· ••• •· r••• • • • •· �•·•• ••· · ·••• ••·••••• • · ······ • •••··· ••• •··•••• ••··• • •••• •••• • · · ••··•·••••• ••• • •·•••· ••• •••••·••·• ••••• • • �··•· •••,•,
5
--- ---- -------
R EQUIRED CONTROLS
Site index (100-year basis) is specified in feet (cols. 2-4) .
A minimum merchantable diameter limit is stated (cols. 6-8) or is based
on one of the following assumptions:
(a)
Merchantable stand diameter at first possible CT (cols. 10-12) :
minimum merchantable diameter is 75 percent of merchantable stand
diameter.
(b)
Total stand diameter at first possible CT (cols. 14-16) :
minimum
merchantable diameter is 87.5 percent of total stand diameter in
natural stands, and 75 percent of total stand diameter in PCT stands.
If more than one diameter is stated, the program (l) uses the specified
m1n1mum merchantable diameter and calculates the other diameters or (2) uses
the specified average merchantable diameter and calculates the specified
average stand diameter.
Intervals between thinnings are specified either as years (cols. 18-19)
or as a given amount of height growth (cols. 20-22) . If some other schedule
is wanted, these columns are left blank and the ages at time of thinning and
final harvest are entered on control card 2.
The number of CT's should be specified (cols. 23-24) the first time
DFIT is used. The report will start with the earliest possible CT for the
given site and will list the CT's plus a final harvest after the last CT at
the same interval as the thinning interval. Review of this� report makes it
possible to choose a thinning schedule that has a long enough interval t�,
get desired minimum thinning volumes and has enough thinnings to keep the·
stand growing vigorously until some specified final harvest date. Generally
this selected schedule will make the interval between final CT and final
harvest greater than the interval between CT's.
CUTTING AGE CONTROLS
Interval from last CT to final harvest can be specified in years
(cols. 26-27) or feet of height growth (cols. 28-30) . If this interval is
not otherwise specified, the simulator will use the thinning interval in
years.
If specified, age at final harvest (cols. 31-33) will override the
statement of number of CT's when there are more CT's than can be made be­
tween first CT and firial harvest. The interval between the last CT and
harvest will be set equal to or less than the thinning interval. If both
harvest age and the thinning cycle are specified, the number of CT's does
not have to be stated.
The first CT can be delayed by specification of total age (cols. 35-36)
or breast-high age (cols. 38-39) at first CT. If, inadvertently, age
specified is less than the age at which the stand reaches the given merchant­
able limit, the program prints a comment and a table, with the first CT
done the year after the limit is reached.
After tables based on schedules developed by these controls have been
examined, precise schedules based on use of control card 2 may seem desira��.
OTHER OPTIONAL CONTROLS
The next optional control is the age of PCT (cols. 41-42) . The program
was designed for ages between 10 and 20 years, and will not run for greater
6
ages. Plantations can be simulated by setting the PCT0age at 2 years. If
this is done some adjustment of predicted growth should be considered to
allow for failed spots , inappropriate genetic stock , and the vicissitudes
of early plantation life. PCT in natural stands enables selection of
vigorous trees that have been tested in situ.
The next option is fertilization. The gains built into the program are
controlled by calling for either fertilized in year of CT (col. 45) or
fertilized at ages specified (col. 48) . These options are activated by
putting "l" in the appropriate column. If fertilized at ages specified is
called for , control card 3 must be prepared and put in the deck. The
assumption is that fertilizer effects vary with site and last 10 years.
See discussion of function 7-0 , p.14. It is assumed that 200 pounds N per
acre is applied and increases growth for 10 years. If the stand is fertilized
at intervals of less than 10 years , the increase is doubled during the
overlapping periods of effectiveness.
To change the growth assumptions in DFIT,a user's estimate of gain or
decrease in growth (cols. 49-52) and time at which it starts (col. 54) can
be entered.
This option makes possible a change in growth rates for reasons
such as genetic improvement , fertilization , or dissatisfaction with built-in
growth estimates. A gain in growth is entered as a percent to the nearest
tenth (cols. 49-52) . A reduction in growth requires a minus sign (col. 49) ,
followed by a percent.
Options for changing growth are: (l) To change growth of both natural
and managed stands a "l" is entered in column 54 of control card l. (2) If
genetic gains are assumed , a "2" is entered in column 54 and a "2" in column
42. This assumes that genetically improved trees are planted. (3) If gains
are assumed to start at date of PCT , a "3" is entered in column 54 and 1a'ge
at PCT in columns 41-42. (4) If gains are assumed to start at date of first
CT , a "4" is entered in column 54. Each gain or loss affects growth from
the selected starting time to the final harvest.
Since these gains or reductions are based on the volume growth function
operating after first CT , they are only approximations for the preceding
period (options 1, 2, or 3) . The approximation can be improved by running
the program twice and specifying a reasonable harvest age (cols. 31-33)
with all controls the same except columns 49-54. The computed change in
yield (CVT) can be compared with the user supplied estimate and the former
adjusted to fine-tune the final estimate.
Diameter ratio of cut to merchantable stand before thinning (cols. 55-59)
may be specified , to override the assumption built into the program that the
first possible CT has a ratio of 1.0 and later CT's have lower ratios with
a bottom limit of 0.8. A ratio thus specified will be used for all thinnings.
An alternative adjustment is discussed under "Changing Functions."
"'
!
!
The next three items give a means of looking at relative stumpage values.
First a discount rate expressed in percent is selected (cols. 60-63) . Then
a stumpage price for final harvest cuts is specified (cols. 64-69) , and last ,
the stumpage for thinnings is stated as a ratio of the harvest stumpage
(cols. 70-73) . All three items must be specified to get the financial report.
(If stumpages are not stated , prices will be 0.)
A financial report is given for each age in the table. Cumulative price
is the stumpage value of previously thinned stands plus standing timber
discounted to age of first commercial thinning. In natural stands it is the -·h
stumpage value of standing timber discounted to same age.
The summary table is called by a "l" in column 75 and the natural stand
table is called by a "l" in column 77. If only the natural stand table is
7
wanted, a 11 111 is put in column 79. It is also necessary to specify ages to
be reported, which is done by using any of the controls that call for reports
on managed stands.
The control card number, which is 1, is specified in column 80.
When control card 2 is used (by leaving both thinning interval columns
(18-19) and height interval columns (21-22) blank on control card 1), age
at first CT is entered in columns 1-3. Successive CT ages are entered in
columns 4-6, 7-9, ... , 58-60.
This allows as many as 19 thinnings because
the last age entered is assumed to be the time of final harvest. A 11211 is
punched in column 80 and the card is placed behind the appropriate control
card 1.
When control card 3 is used (by punching 11111 in col. 48 of control
card 1) , age at first fertilization is entered in columns 1-3. Successive
fertilization ages are entered in columns 4-6, 7-9, 58-60. Since fertiliza­
tion effects are assumed to last 10 years, it is unlikely that more than
four or five ages will be specified.
A 11311 is punched in column 80 and the
card is placed behind control card 1, or control cards 1 and 2.
Function List
The equations that control DFIT have been listed at the end of the
program, making it easy to change assumptions. Some changes can be made
with no concern for other equations, some imply changes in other equations,
and others require changes to maintain consistency. Such''dependencies will
be noted in the ensuing discussion.
The symbols used here and listed iQ
the appendix are not the same as those in the program. Those used in the
program must be used in changing the program. Many equations in this
report state the dependent variable as log y (written as log y) to simplify
10
The functions in the program all state the dependent variable
typesetting.
as y.
NATURAL STANDS
Calculate breast-high (b.h. ) age of natural stand, given total age and
site index:
A
- 13.22 + 0. 033S.
B = AT
(0-1)
If this equation is changed, equation 0-2 must be changed and equations
0-3 and 0-4 probably should be.
Calculate total age of natural stand, given b. h. age and site index:
A
T
= AB + 13.22 - 0. 033S.
(0-2)
If this equation is changed, equation 0-1 must be changed, and equations
0-3 and 0-4 probably should be. This equation implies a linear relation
between site index and time from germination to breast height.
Calculate quadratic mean diameter of natural stand, given b.h. age and
site index:
0 25
log DG = 0.1097 - 3.4857/(AB ) ·
+ 1. 0531 log S.
(0-3)
<��
If this equation is changed, equation 0-4 must be and equations 0-5 and
0-6 probably should be. This equation and several others are based on reanal­
ysis of the data on which USDA Technical Bulletin 201 (see footnote 5, p. 3)
was based, plus some recently measured plots that furnish more information on
8
young stands on poor sites. They give estimates for natural stands that
are close to, but not identical with, those in Bulletin 201.
Calculate b.h. age of natural stand, given quadratic mean diameter and
site index:
(3. 4857/(0.1097 - log D + 1.0531 log 8) ) 4.
AB
(0-4)
G
=
This equation is derived from equation 0-3, and 0-3 must be changed
if 0-4 is. See the paragraph following equation 0-3 for other discussion.
Calculate trees per acre in natural stand, given b.h. age and site
index:
0 25
log N
3.9108 + 5.2306/(AB) ·
- 1.5803 log S.
(0-5)
=
This equation is derived from the same data as equation 0-3.
0-3, 0-5, and 0-6 are a group that must be kept consistent.
Equations
Calculate basal area per acre in natural stand, given b.h. age and site:
log G
=
0 25
1.8669 - 1.7408/(A ) ·
+ 0. 5259 log S.
B
(0-6)
This equation can be derived from equations 0-3 and 0-5 by:
log G
=
log N + 2 log D + log 0.005454154.
This relationship must be preserved if equation 0-3, 0-5, or 0-6 is ch_�nged.
f.
'
Calculate average height of dominant and codominant trees in natural
stand, given total age and site index:
log Hn
0.1567 - 15.673/A
=
T
+
log
s.
(0-7)
This equation comes from the same data as equation 0-3 and gives close
approximation of Bulletin 201 (see footnote 5, p. 3) site curves. It is
independent of equations 0-3 through 0-6. If it is changed, equation 0-8
probably should be and equation 2-0 must be.
Calculate volume/basal area ratio of natural stand, given dominant and
codominant height:
log V/G
-0.0282 + 0.7917 log H .
D
=
(0-8)
This equation, derived from same data as equation 0-3, can be combined
with equations 0-6 and 0-7 to get direct estimates of volume per acre in
natural stands. It starts the volume estimate in the simulator.
Calculate volume per acre of natural stand, given site and age.
"'
log V
!
2-1.
=
1. 9628 - 12. 4083/A
T
0 25
+ 1.3176 log S,(0-9)
- 1.7408/(A ) ·
B
This equation, derived from 0-6, 0-7, and 0-8, is used only in equation
It does not appear alone in the function list of program DFIT.
STAND DENSITY RELATIONS
Calculate top limit of basal area in natural stand, given quadratic
mean diameter:
1.9882 + 0.4994 log D .
log GL
(l-0)
G
=
9
This equation is derived from Reineke's stand density index (§ee footnote
3, p. l) which is based on log D G
f (log N) . Since G = 0. 005454 ngN, the
density index can be expressed by any of the six_relations among pairs of
the three variables. As used here, for a given D G, the limit of either G or N
is 1.5 times the average density of all plots in the data set described under
equation 0-3. Changes 'in this equation y.'ill affect operation of equation 2-3.
==
CT :
Calculate trees per acre in a PCT stand, given diameter at first possible
log
N
= 3,9591 - 1.5006 log D .
F
(l-1)
This equation is derived from the same relation as equation 1-0. The
stand density is about 76 percent of the average of all plots.
If this equation
is changed, equation l-2 must be changed.
Calculate basal area per acre of merchantable trees, given average diameter of merchantable trees at first possible CT:
log G
M
= 1.6958 + 0.4994 log
(1-2)
If this equation is changed, equation 1-l must be.
Calculate recommended level of basal area after first CT, given average
diameter of merchantable trees before thinning:
log G = 1.3275 + 0.6917 log D .
M
R
(1-3)
This equation is derived from same relation as equation l-0. It ���es
a basal area of about 50 percent of average natural stand density when stand
diameter is 8 inches and 80 percent when stand diameter is 30 inches. If
this equation is changed, equation l-4 must be.
Calculate average diameter of merchantable trees in stand, given recom­
mended level of basal area after CT:
log D
M
= -1,9192 + 1.4457 log G .
R
(l-4)
This equation is derived from equation 1-3. The two equations are
used with a given d/D ratio to estimate diameter and basal area of merchant­
able trees after thinning. See also equations 6-0 and 6-l.
GROWTH FUNCTIONS
Calculate 1-year height growth of dominant and codominant trees, given
total age and site index:
log dHD/dA = 1.7141 + log S - 15.673/AT - 2 log A .
T
T
(2-0)
This equation is the derivative of equation 0-7.
Equation 2-0 is
solved for the middle of the year to get close estimate of the year's growth.
Calculate 1-year volume growth of stand after first CT, given total age
and site index:
log V = 1.9628 - 12.4083/A - 1.7408/(A )0·25 + 1.3176 log S; (0.9)
B
T
... �,�
2
�h
so log dV/dA = log V + log 2. 3026 + log(l2,4083/(A )
T
1 25
+ 0.4352/(AB) · ) .
2
log dV = log (1.12 + 0.0105 A - 0. 00005A );
A
T
T
if (A GT 105), log dV = 0.22304.
T
A
<
10
Combining the last two equations gives:
A
log dV/dA = log dV + log dV/dA.
A
(2-1)
This equation uses equation 0-1 to get the b.h. age , given total age.
The derivative of equation 0-9 was compared wi
. th Staebler's§_/ and
l/
Curtis•
estimates of gross growth for ages 30 to 100 and adjusted (by use
of log dVA) to approximate gross growth ratios.
With a better data base ,
an interaction of adjustment by site might show up.
Calculate adjustment to volume growth , given total age of first CT:
V
A
= (405 - A T) /400.
(2-2)
This equation reduces growth by 0.25 percent for each year CT is delayed.
If CT is scheduled at age 25 , the growth would be 95 percent of full growth.
This allowance is made because crowns become progressively less able to
respond to release as first CT age increases.
Calculate competition growth reduction multiplier , given ratio of average
basal area of living merchantable trees to top limit of basal area in natural
stand (Gz) :
V = (l-16(Gz - 0. 5) 4) .
(2-3)
A
The ratio Gz is calculated for every period of growth (Gz = GM/GL).
GL comes from equation 1-0. The reduction multiplier has little effect on
growth until stand density is considerably above average for dense natural
stands. If a thinning schedule is assumed that includes a long period after
an early CT on a good site , the stand will progress to above average density.
Thinned stands will probably grow better than natural stands at these high
densities for a while , and then in a dry summer lose groups of trees to
mortality. It was simpler merely to slow diameter growth than to simulate
The growth reduction multiplier also
a hypothetical pattern of mortality.
reduces growth in open stands. This symmetrical function gives an approxi­
mation of the plateau of maximum yield hypothesized for stands of different
densities.
VOLUM E FUNCTIONS
The expression V/G = f(HD ) is the main control over total cubic-foot
volume of natural stands in the simulator , and the expression dV/dA
= f(AT , A c , S) controls total volume growth.
Other volume functions
estimate total volume of stand components and merchantable volume.
Calculate tarif diameter function , given diameter:
F
2
2
+ 16) (1.0378
(0.004978D ) /(0. 005454(D
G
G
(D /lO)
) ) - 0. 1745) .
+ 1. 4967(0. 0134 G
(3-0)
I
;.,J
£1 Staebler, George R. 1955. Gross yield and mortality tables for fully stocked
stands of Douglas-fir. USDA For. Serv. Pac. Northwest For. and Range Exp. Stn.
Res. Pap. 14, 20 p., illus. Portland, Oreg.
11 Curtis, Robert 0. 1967. A method of estimation of gross yield of Douglas-fir.
For. Sci. Monogr, 13, 24 p., illus.
11
�--------
F*V/G
This equation is used in various ways in the program in the re g �tion T
(where T is Washington Department of Natural Resources tarif). -1 When V/G is
predicted from H a�d D from total age and site, a stand tarif can be calcu­
D
G
lated. Then, if a D for a stand component is estimated, the corresponding
G
This relation is approximate, not exact, and is
V/G can be calculatea.
applied generally to smalle$t stand components so the error in volume is
minimized.
Volumes of larger stand components are estimated from volume of
total stand and volume of small components.
=
Height growth of submerchantable trees is calculated from their V/G on
the basis of average of current stand tarif and tarif at first CT.
Calculate stand mean height, given average height of dominants and
codominants, and total number of trees per acre:
H * (3040 - N)/3000;
(3-1)
D
HD.
if (H GT H ), H
D
M
M
This equation is based on· H
0. 8 HD for 640 trees per acre, and H
H
D
M
M
for 40 trees.
Mean heights for components of stand are obtained by adjusting
this value by relations between V/G ratios.
H
M
=
=
=
=
Calculate cubic volume to a 4-inch top (CV4), given total cubic volume,
stand diameter, and mean height:
2
C
+ 0. 3221/D
0. 8758 + 0. 001049H - 0.000002824H
M
a
M
U
- 3
- 45. 647/D
(8:0.2)
.
G
=
The relation CV4
C *V appears in the program and completes merchantable
u
volume calculation.
=
Calculate International 1/4-inch volume to a 5-inch top (IV5) , given
total cubic volume, stand diameter, and mean height:
C
I
=
2
+ 31. 058/D 2
2. 408 + 0, 04633H - 0. 0001082H
M
M
G
- - 3
- 10. 675H /D
.
M G
The relation IV5
=
(3-3)
C *V appears in the program.
r
Calculate Scribner volume to a 6-inch top (SV6), given total cubic
volume, stand diameter, and mean height:
- 2
- 2
1. 728 + 0,05048H - 0. 0001192H
- 78,562/D
M
M
G
- - 2
- l. Ol66H /D
.
M G
c *CVT appears in the program.
The relation SV6
8
(3-4)
=
�/ Turnbull, K. J., Gene Roy Little, and Gerald E. Hager. 1963. Comprehensive
tree-volume tarif tables. State Wash., Dep. Nat. Resour., 23 p., illus.
12
--
� -------��c-c·c·
SUBMERCHANTABLE TREES AN D MORTALITY
Calculate number of submerchantable trees per acre in a natural stand ,
given the mean diameter of a natural stand of current age and site and the
minimum merchantable diameter:
log N
s
+
= 3.8622
3.1994 log D - 4.70 log D .
G
m,
(4-0)
This equation is used for natural stands both with and without CT.
Equation 4-1 must be changed if equation 4-0 is.
Calculate basal area per acre of submerchantable trees in a natural
stand, given the mean diameter of a natural stand of current age and site
and the minimum merchantable diameter:
log G
s
+
= 1.4034
4.9394 �og D
m
- 4.44 log D .
G
(4-1)
This equation is used for natural stands both with and without CT.
Differences between estimates at successive ages give submerchantable
mortality between those ages. Equations 0-5 , 0-6 , 0-7 , and 0-8 are used to
calculate net vital statistics of natural stands at successive ages. Equation
2-1 gets gross volume growth. Given these values and an estimate of sub­
merchantable mortality , the merchantable mortality can be estimated. If
equation 4-1 is changed , equation 4-0 must be changed too.
PRECOMMERCIAL THINNING A DJUSTMENTS
Calculate adjusted site index for superior height-growth after PCT ,
given site index before PCT:
;�· '
s
P
= s (1
+
2
(210 - s) /9oooo).
(5-0)
if (S GT 210) , SP = S.
This equation increases site index for the growth stimulation between
PCT and first CT. In this period number of trees is assumed to be reduced
to a level that promotes rapid growth. Improved vigor of the stand is
assumed to last indefinitely. This function can be modified.
Calculate age at first possible CT for_stands PCT to about 400 trees
per acre , given total age (based on 8-inch DM and adjusted site index) and
age at PCT:
if (A GE 15 and A LE 20) ,
p
P
AF = A
T
(0. 68
+
0.016Ap).
if (Ap GE 2 a.nd Ap LE 14) ,
(0.8244 + 0.004333 A /
p
T
3
+ 0.01667 (A /10) ).
p
A
1 +
2
0.0150(A /10)
p
(5-1)
When age at PCT is under 20 years , these e �tions reduce age at first
possible CT. The greatest possible reduction--1
PCT at 2 years , used to
estimate plantation growth--is to 83 percent of
1 at CT without PCT.
Calculate adjusted basal area per acre in PC
tand with less th�
400 trees per acre , at the age when a 400-tree staHu· would average 8 inches , ,­
given the average diameter of merchantable trees at first possible CT:
G = 180.22 - 5 DF.
S
(5-2)
13
-�
This equation controls the growth of stands whose average merchantable
diameter at first possible CT is greater than 8 inches. DFIT calculates and
reports number of trees per acre at age of first CT in such stands. DFIT
grows these stands to desired size from adjusted basal area. The number of
trees per acre in these stands is stated for age at first CT. The number
left after PCT may be greater than this if mortality is anticipated.
COMMERCIAL THINNING
Calculate ratio of diameter cut to diameter merchantable stand before
CT, given minimum merchantable diameter and present merchantable diameter:
(6-0)
d/D = (4/7)(1 + D /DM);
m
if (d/D LT 0.8), d/D = 0.8.
This calculation sets d/D at 1.0 when CT is same date as first possible
CT and drops it to 0.8 when the average merchantable diameter is about
double the merchantable diameter at first possible CT. A constant d/D can
be selected by entering it in columns 55 to 59 of control card 1.
For other
d/D this equation can be changed.
Calculate two-thirds of merchantable basal area per acre before CT and
use the result as the limit to residual basal area from equation 1-3:
(6-1)
-,
1.
'
This expression is used as the limit in the first CT. A similar limit
is imposed on second and subsequent CT's where it would be effective only
with extremely long thinning intervals.
FERTILIZER ADJUSTMENT
Calculate adjusted site index and use it to calculate growth during
the 10-year period after 200 pounds of nitrogen per acre are applied, given
site index before fertilization:
log S
N
= log S + 0.7590 log ((830 - S)/600);
(7-0)
if (log S N LT log S), log SN = log S.
This equation makes the following adjustments for each of the 10 years
after fertilization:
s
SN
dV multiplier
80
94.76
1.25
llO
126.33
1.20
140
155.67
1.15
170
182.75
1.10
200
207.55
1.05
-·�t,-,
The equation implies no gain at or above site 230. This might give
unreasonable answers if controls also call for large genetic gains on high
sites. Volume increment gains are distributed between diameter and height
14
growth by changing the site index to get the assumed increase in volume
increment.
This improves height increment, and the diameter (basal area)
improvement is based on the volume-basal area ratio appropriate to the
attained height. Increment returns to initial site index after 10 years.
G ROWTH ADJUSTM ENT
Calculate an adjusted site index that changes total volume growth,
given unadjusted site index and user selected increase or decrease in growth.
log S = log S + (log (1
A
+
R/100))/1.3176
(8-0)
This equation changes site index used to calculate growth or yield. It
is applied to equations 0-1 through 0-9 when a change in growth affecting
both natural and managed stands is assumed.
It is used in equation 5-0
Finally, it can be used in
for early growth of planted or PCT stands.
equations 2-0 and 2-1 to change growth of managed stand after first CT.
Changing Functions
Several of the functions just discussed can be changed without upsetting
internal relations in DFIT. If changes are made, the user should remember
that the program as written was balanced against observed growth on thinned
plots, and changes may upset this balance.
The first three changes discussed
below are for thinning controls and can be fairly large without upsetting
balance of DFIT.
Basal area after first CT is limited to two-thirds the basal a�� a
before thinning or to a recommended level based on average merchantable
diameter before thinning. The two-thirds limit for first CT is easily
changed by adjusting equation 6-1.
To change the recommended basal area level after thinning, replace
equations 1-3 and 1-4 with any equations involving only average diameter
and basal area. Most competition indexes can be altered to a per-acre
relation of this kind.
The ratio of average diameter cut to average diameter of merchantable
trees before thinning can be changed to a fixed value by use of control
columns 55-59.
If a changing ratio is wanted, equation 6-0 can be replaced
with any other relation expressing d/D as a function of merchantable diameter
limit and current average merchantable diameter.
Fertilizer effects for 10-year periods are easily changed by replacing
equation 7-0.
The coefficient of the adjusting term in equation 7-0 (0.7590)
is the reciprocal of the coefficient of the site term in equation 0-9
(1.3176).
Estimates of merchantable volume can be changed by altering equations
3-1 through 3-4.
Equations 3-2 to 3-4 express the ratio of merchantable
volume to total volume as a function of mean tree height and mean tree
diameter.
Other functions can be changed as indicated in the discussion of the
function list.
It is also possible to add features to the program by internal modifi­
cation. Several such modifications have been made since the first draft of
this paper was written. A list of other modifications suggests the need
for a choice between early publication of a useful simulator and later
15
publication of a more nearly perfect simulator .
and suggested modifications are listed below :
1.
The former has been selected,
Controlling period between thinnings based on basal area growth .
2. Listing of mean annual increment and periodic annual increment at
each thinning date for managed stands .
3.
Cumulating mortality and reporting both net and gross m . a . i. and
p . a . i . for natural stands .
4.
Controlling IV5 so DFIT will report either International 1/4-inch
or International 1/8-inch rule .
5.
Controlling value so stumpage can be based on any measure of vo lume
(not just Scribner) .
6.
Ten years after fertilization , changing site to that indicated by
attained tree height .
�--7 . Stand description supplied by user .
(
Estimating yields of understocked stands with densities between PCT
8.
and natural stands .
The adjusted ages and sites of such stands at first CT
would be between those of PCT and natural stands .
9.
Estimating yields of extremely open stands .
10 .
Introducing one or more stochastic elements such as :
ment, suppression mortality, d/D ratio , gf G ratio .
11 .
volume incre­
Adjusting growth rate for any specified period.
Only the 7th to 1 1th modifications require much more than programing
time .
To modify DFIT to accept a wide range of stand conditions would ; _ - .
require inclusion of growth limiters appropriate to such a range and develop­
ment of suitable descriptors for abnormal conditions .
16
Appendix
SYMBOLS
A
c
CT
CV4
CVT
d/D
D
f:i
DFIT
F
gjG
G
GE
ii
IV5
N
PCT
R
s
SV6
T
v
Y/G
v
Stand age (years)
Total cubic-foot volume adjuster
Commerci a l' thinning
Cubic volume to 4-inch top , no stump (cubic feet)
Total cubic volume (cubic feet)
Ratio di ameter cut to diameter before thinning.
Diameter (inches)
Average diameter ( inches)
Douglas-fir interim tables
Diameter function
Ratio basal area per acre cut to basal area before thinning
Basal area per acre (square feet)
Greater than or equal
Mean heikht (feet)
International 1/4-inch board-foot volume to 5-inch top
Number of trees per acre
Precommercial thinning
Change in growth rate
Site index (100-year basis)
Scribner formula board-foot volume to 6-inch top
Department of Natural Resources tarif
Total cubic-foot volume per acre
Volume to basal area ratio (feet)
Adjusted volume
SUBSCRIPTS
A
B
c
D
F
G
I
K
L
m
M
N
p
R
s
s
T
u
z
Adjusted or adjuster
Breast high
Commerci al thinning
Dominant and codominant
First possible
Basal area
International log rule
Limit
Limit
Merchantable limit
Merchantable (or mean in mean height)
Nitrogen fertilizer
Precommercial thinning
Recommended
Submerchantable
Scribner log rule
Total
Cubic volume
Ratio
17
I
I
I
TABLE
lA
SUHHAI!Y l A eL£
•
DOH +
HEAN •
TOTAL COOOH
STAND
AGE HEI GHT
DOH
COHPON�NT
INCHES•
YEARS FEET
T O T AL BEFORE 7 . 0 2 •
36
74
MERCHANTABLE a . o 1 •
46
60
PER
VOLUME
ACRE
� - INCH
N
.. l/
CU FT . CU FT I
�05�
1 748�
46� 1
1 66 1 2
361 4
4 U3
•
TREE$
PER
ACI" E
89 1 6 •
639 . 0
.. 0 2 . 1
PE R
�CR£
..
�;i ��
�c���'tt
:
89 1 6 •
Gy
1 7 1 .7
140.8
92
T O T A L BEFORE 9 . 27 •
MERCHANTABLE 1 0 . 0 7 •
5 29 1
5046
�856
�699
25264
25042
1 77 0 5 •
1 77 0 5 •
3�6 .9
267 . 9
1 57 . 9
148.3
0
TOTAL BEFORE 1 2 . 4 9 •
MERCHANTABLE 1 3 . 0 9 •
6646
6560
63�9
6290
37827
37754
:3 0 3 .. 9 ..
3 0 349 •
20 I , 8
180.3
17 1 .6
168.�
I I
NATURAL STANO T A BLE
SITE INO£X= I �O . O
DOH +
TOTAL COOOH
AGE H E IGHT
YEARS FEET
36
46
60
73o7
91.6
I I 0,
ll
y
I
18
(100-YEAR BASIS)
•
•
M E AN
OBH
INCHES
HEAN
GY
s a FT
�EAN
VOL
CU FT
RATIO •
VOLUME
�-INCH
cu F T
CU F T
T OTAL
SUBMERCH
MERCHANTABLE
7.02
�.89
a.OI
. 26 87
. 1 303
.3502
7.58
3. 1 2
1 0. 20
28.20 •
21 . 9 2 •
29. 1 � .
�84 1
n8
.. 1 0 3
It 0 54
4�0
36 1 �
SUBHERCH �.ORT
HERCH HORT
4 .62
6 . 79
•
. 1 2 66
25 1 3
3.00
7.35
23.72 •
29.25 •
5 0 ..
295
292
245
T OTAL
S UBHERCH
MERCHANTABLE
9.13
5.05
9 .7 1
.4542
. 1 3 93
, 5 1 �2
��.22
3.56
1 7 . 44
33, 5 1 •
25 . 59 •
33 . 9 2 •
6559
2 .. 6
63 1 3
5 9 99
1 57
5 6.. 2
307�0
2 .. 8
3 0 .. 92
SUSHERCH MORT
HERCH MORT
4 . 98
7.63
, 1 3 5�
. 3 1 76
I0.61
3 . ....
2 5 . "39 •
33.41 •
1 63
917
102
608
1 39
3697
2 0 61t
1 1 . 69
5.21
I 2. 0 5
.7458
. 1 ..8 0
. 79 ?. 5
28.69
� . o.,
30.63
3 8 . 74 •
27 . 33 •
38.90 •
656 1
87
8494
6 1 59
59
6 100
415�4
81
47422
37012
•
37072
•
STANO
COMPONENT
TOTAL
SUBHERCH
MERCH A NT ABLE
Board fee t .
Basal
•
area .
VOLIG
U
PER
I
N
ACRE
�;i ��r, l/ �����'tt
1 7 �84
872
1 66 1 2
I
525
0II
•
8916
•
89 1 6
•
388
2 0 967
2 0 967
•
•
•
•
•
•
GY
nEES F£R C U RR E NT
PER ACRE
PRIC E
$
ACRE S Q Fl
639,0 1 7 1 . 7
236.8 J t . 9
402 . 1 1�0.8
1 67 . 9
40.2
21 .3
10. I
�30.9 195.7
9.6
69.0
36 l o 9 1 & 6 . 1
47.5
e 6 . 1t
O I SC
PRIC£
$
1 337
1 337
3 1 1t5
1 7 56
556 1
1 37 3
··
;�
6 . ..
27 . 5
297 . 0 22 1 . 5
3,2
21.5
275 o 5 2 1 8 . 3
TAB L E 2
PROGRA!i
DFIT
DOUGlAS-FIR HANAGEO Y IELD T A BlES
S I T E INDEX= l 4 0 o 0 ( 1 0 0-YEAR B A S I S I
T H E CONTROL CARD SPEC I F IES T H A T
D I AMETER O F THE HF.RCHANTABLE P A R T O F THE STANO AT THE F IRST POSSIBLE
T H E H I NIHUH MERCHANTABLE OBH I S 7 . 5 0 INCHES ,
THE STANO HAS NOT HAD A PRECOHHERCI A L THINNI NG ,
THE' THINNI NG I NTERVAL IS 1 0 YEARS,
NUMBER OF COMMERCIAl T HINHIN GS= 2 .
TOTAl A G E A T HARVEST= 60 YEAil S o
HARVEST STUMPAGE= $ 1 5 0 , 0 0 PER T �OUSANO BOARD FEET SCR I B NER,
THINN ING STUMPAGE= $ 1 20 , 0 0 PER THOUSAND BOARD FEET SC RIBNER ,
D I SCOUNT R ATE= • 0 6 0 o .
DOH •
TOTAL COOOM
AGE HEI GHT
Y E A RS FEET
44. 1 8 6 . 6
lt5
90. 1
•
HEAN
OBH
INCHES
6 o 75
HEAN
G 1/
TOTAL BEFORE
SUBHERCH
MERCHA NT ABLE
CUT
KERCH LEAVE
TOTAL LEAVE
STANO
COMPONENT
FIRST POSS
SUH GROSS
SUH HERCH
SUH OF CUT
55
104o2
60
II O.l
Z
VOlUME
PER
4-I NCH
CU F T
C U FT I
6255
•
•
6198
929
5815
7J2
29305
2 5 23
1 94 26
6 26
31 o 6 1o "
33o80 •
3 3 , 8·S •
5469
182 1
36 .. 6
4577
5063
1691
339 1
4 1 23
26782
8 896
1 7 685
2 04 0 9
1 88 0 0
6 227
1 2 5 7..
I 3200
•
6398
5469
1821
58 1 5
5083
169 1
29305
2676 2
8696
1 91o26
1 86 0 0
6 2 27
2060
530
412
1 369
261
•
6 1 07
414
5 7 55
334
3 26 1 1
" 43
24883
389
•
•
•
5 6 94
1 1 39
4554
4966
5421
1 0 79
4 3 1t 2
4 6 76
3 1 468
6 1 37
2 5'3 3 2
26475
2449'+
lt 646
1 9 649
2 0237
•
•
8456
751 5
2960
7859
7 1 12
2170
4 2 6'1'7
40364
1 5 0 33
3 1 39 1
30721
1 0672
30. 16 .
9H
1 20
95
3 08
89
. 4 1 76
�EAN
VOL
CU F T
I 3o63
voltG!.
RATIO "
3 2 . 64 •
6 , 91
6o l 2
o 4346
• 2 0 45
1 4 .36
5o95
33 , 05
2 9 . 07
I O, 1 2
1 0 . 07
10.15
6.56
5588
5531
• 5618
• 4014
1 8. 9 1
1 8 . 69
19.02
13. 15
so
F'r
•
•
3 2 . 76
•
•
1 0 . 07
VOL GROWTH
SUBHERC H HORT
6.02
o l 975
5o70
28.86
TOTAL BEFORE
SUBHERCH
1 0 , 68
6.26
o 64 5 5
• 2 1 46
23.95
6o54
37 . 1 0
3 0 . 45
MERCHANTABLE
CUT
MERCH LEA�E
TOTAL LEAVE
1 2. 0 2
11. 15
1 2 . 27
1 0.82
o 7875
o 67 6 3
821 1
. 63 8 4
29.69
2 5 . 22
3 1 . 06
23.67
37 . 7 0
37 , 1 9
37 . 83
37o 0 6
SUH GROSS
SUH HEIICH
SUH OF CUT
60
c''c � HERC I A L
•
1 0 .42
VOL GROWTH
SUBHERCH HORT
6ol3
TOTAl B EFORE
SUBHERCH
•
•
•
•
ACRE
�rl N��
..
Y
•
6 - I NCH •
SCRIB _gj "
...
THINNING I S 1 0 , 0 0 INCHE S ,
G l/
TREES P E R CURRENT
I'ER ACRE
PRICE
ACRE s a FT
$
459 o 0 1 9 l o 6
..
•
•
269o2 1 6 l o 6
9 7 . 4 5J . 9
1 9 l o8 1 0 7 , 7
34 8 . 0 1 3 9 . 7
.
97.4
193.6
16 1 . 6
53.9
93.0
l 8o 4
•
'--·
•
2 5 5 . 0 1 6 .. . 6
63.2 1 3 . 6
•
l 9 l o6 1 5 1 . 0
45.2 30.6
1 4 6 . 6 1 2 0 ...
2 0 9 . 9 1 31t , O
•
142,6
23 6 o 9
2 0 1t o 9
64, 5
1 9.3
.. . o
•
•
•
6.19
1 2. 0 0
6 , 34
o7852
• 2 1 90
30.�2
6 o78
311 . 71o
3 0 o 97
•
•
5796
298
5520
2 't 3
:5 2673
831
260 I I
310
•
•
1 90 . 5 1 4 9� 6
43o9
9,6
HER C H A NTAI!LE
1 3 , 23
o 9547
3 7 o lt 9
3 9 o 27
•
5498
5 277
3 1 64 2
2570 1
•
146.6 140 . o
HARVEST
1 3.23
o 9547
37 o 4 9
3 9 . 27
•
5498
5277
3 1 842
2 57 0 1
..
146o6
•
94 0 6
8458
6458
6798
801o7
80t,7
4 93 6 3
46875
46675
3 7 2 54
3 6 573
1 6571
•
256 o 5
224 . 5
2 8 9 . 2 2 2 ft o 5
I IOol
CUH
PRICE
$
44 5 . .. 1 91 , 6
156, 2 3 1 o 9
2052
•
D ISC
PRICE
$
•
2820
747
2820
747
2820
3674
557
2052
31 1
2799
3855
1 60 9
2667
/.'
l fo O . o
GRANO TOTAlS
SUH GROSS
SUH HERCH
SUH OF CUT
l/
Basal
area .
..
l l o93
Y
Board feet .
19
TAB L E
PROGUH
DOUGLAS-FIR
OFIT
� A N A G E D Y I ELD T A!!U'S
S I T E I NDEX= 1 � 0 , 0 ( 1 0 0 -VOR B A S I S )
T HE CONTROL C A R D SPEC I F I E S T H A T
I
T H E F I R S T C O H H E R C I A t T H I NN I N G H ill OCCUR W H E N T O T AL A G E I S
4 0 Y E AR S ,
D I A METER OF T H E TOTAL S T A N O A T T H E F I R S T P O S S I BL F C OH H £ R C I A L T H I N N I N G I S
6 , 0 0 INCHES ,
T H E M I N I H U H MER C H A N T ABLE D B H I S
THE STANO H A S NOT H A D A PREC O � HERCIAL T H I N N I NG ,
I 0 'I E Ail S ,
T H E T H I N NI NG I N T E R V A L I S
7 , 0 8 I NC H E S ,
2.
N U M B E R O F C O H H E R C I AL T H I N N I N GS=
6 0 VEA�S.
TOTAL A G E AT H A R V E S T =
1 5 0 , 0 0 PER T H O U S A N D B O A R D F E E T SCRIBNER ,
HARVEST S T U M P A G E = $
1 2 0 , 0 0 P e R T H O U S A N D B O A R D FEET SCRIBNER ,
T H I N N I N G STUMPA G E= $
D I SCOUNT RATE= o 0 6 0 0 .
OOH +
TOTAL C O O O H
HEIGHT
�GE
FEET
YEARS
35o9
73 .5
40
50
60
60
6 1 .5
97 o 6
I I 0, I
HE A N
G 1/
s a FT
. 26 7 3
MEAN
VOL
c u FT
7,52
VOL/G lJ
RAT I O •
26. 15 •
•
VOLUHE
PER
ACRE
•
6 - I NCH
4 - I NC H
5 - INCH
y
CU F T
CU FT
SCRIB '£/ •
INTl 114
•
4826
TOTAL BEFORE
SUBMERCH
7 o6 9
4 o 96
.�398
, 1 3 43
1 0.36
3 .3 1
3 0 , 53 •
2 4 . 64 •
5556
.. 5 1
4665
276
2 2 6 58
.. 9 2
1 3662
MERCHANTABLE
CUT
HERCH � E A V E
T O T A L L E A VE
6 o 67
6 . 38
8.83
7.71
.4100
o 3633
.4248
o 3 2.. 1
I 2,79
l l o65
I 3,3 I
9 . 84
"3 1 . 1 9 •
"30 o 9 1 •
3 1 . 33 .
3 0 . 37 •
5 1 07
1 6 67
3420
3 87 1
4607
I 5I I
3 0 97
3 3 7..
2 2 �67
72 1 8
1 5 1 .. 9
1 56 4 1
1 3662
4 2 58
9 '+ 0 3
9 lo 0 3
•
5558
5 1 07
1 6 67
4865
4607
15 1 1
2 2 8 58
2 2 3 67
1218
1 3 6 62
1 "3 6 6 2
4258
STANO
C O M P O NENT
F IR S T P O S S
8 o36
V O L G � O HTH
S U B H E R C H MORT
4.86
. 1 30 1
3.18
24o42 •
2204
264
170
2 63
T O T AL B E F O R E
SUSHERCH
9 . 96
5, I I
o 54 1 0
, I 422
I 9 ,0 5
3.7 1
35 , 2 2 •
26o l 3 •
5792
175
5391
1 14
29207
155
21313
HERCHANTAIJLE
GUT
HERCH L E A V E
TOTAL LEAVE
I0.6 I
9.49
I I ,I8
I 0, I 5
6 1 40
.49 13
o 68 1 6
. 5623
2I ,86
1 7 . 07
24.50
I 9, 9 0
35.60 •
3 4 . 7'+ •
3 5 o 95 •
35.40 •
5617
I 5 58
4058
t,2 3 3
5 27 7
1 4 '+4
3 63 3
3 94 7
29052
762 1
2 1431
2 1 567
2 13 1 3
5265
1 6 0 '+8
1 6 0 48
•
776 2
73 0 4
3 2 45
7071
6767
2955
3 66 8 8
36270
2 55 7 1
25571
•
1 97 5
91
56
62
SUH G R O S S
SUH HERCH
SUH OF CUT
6 o6 3
VOL G R O H T H
SUBHERCH H O R T
5o02
•
•
25 o 88
1 48 3 9
o l 37 3
3 , 55
•
.8439
1 480
32o69
4. 0 2
J e o74 •
6118
86
5844
58
34853
71
•
9523
1 2 .44
S o2 1
MERCHANTABLE
13.09
. 9342
36,4 I
3 8 o 98 •
603 1
5785
3 47 8 1
27975
HARVEST
1 3 . 09
o 93 4 2
36.4 I
3 8 o 98 •
60 3 1
5785
3 47 6 1
27975
9737
9271
9277
9 0 26
8740
8 7 .. 0
500 16
49620
lt 9 6 2 0
31498
3 7 .. 9 6
37498
27 . 1 1
•
•
•
•
•
G lf
53 5 , 7
1 36,3
182.0
1 8. 3
399o 3
142o4
256.9
393.3
1 63 o 7
54. 6
I09o2
1 27 . 5
1 .. 2 . 4
182.0
l63o7
5\.6
•
89.3
I I o6
•
304.0
47o0
1 64 o 4
6o7
•
256.9
9 I, 3
165.6
2 1 2.7
1 57 . 8
44 . 9
I I 2o9
If 9o6
•
23 3 , 7
•
•
.
•
Basal
20
a re a .
•
£/
Board
feet ,
•
•
CUH
PRICE
2 0r, 9
51 1
2049
3 1 97
632
1 78 5
353
2296
4 1 96
I 308
2049
511
'
'
��--
23 0 . 6
2 1 2.3
99o4
25o5
3o5
l 87 o I
2 1 .5
1 57 o 9
3,2
1 65 . 6
l 54 o 7
165.6
154o7
TOTALS
1 0 .80
DISC
P R IC E
PER
TREES
CURRENT
PER
ACRE
PRICE
ACRE
S O FT
$
64 l o 5 1 7 1 o 4
•
•
27975
T O T AL BEFORE
S U B HERCH
SUH G R O S S
SUH HERCH
SUH OF CUT
ll
•
SUH GROSS
S U H HERCH
SUH O F CUT
I I0, I
GRANO
•
•
HEAN
OBH
I NC H E S
7 . 00
27 2 . 5
2 5.. . 2
399o 3 254 o 2
2 1 72
TAB L E 4
PROGRA�
OFIT
UOUGl AS-FI� "A �AGED Y IELD T ABlf.S
S I T E INDEX= 1 4 0 o 0 ( I G U-'VE AR 8 A S I S I
T H E CONT�Ol CARD SPEC I F I E S T H A T
T H E H I NI�UH MERCHANTABLE O B H I S & . o o INCHES.
1 0 Y E A� S .
T H E STANO HAS PRECO�MERCIALLY T H INNED A T AGE
T H E T H IN � I NG I NTERVAL I S 1 0 YEARS ,
NUHBER OF C O MMERCIAL T H I N N I N GS= 2 .
T O T Al A G E A T HARVEST= & 0 Y E ARS .
HARVEST STUHPAGE=t 1 5 0 , 0 0 PER THOUSAND BOARD FEET SCRIB�ER ,
THINNING STUMPAGE=$ 1 20 . 0 0 �ER THOUSAND BOARD FEET SCRIBNER ,
DI SCOUNT RATE= , 06 0 0.
S I T E I ND E X HAS ADJUSTED T O 1 4 7 , 6 BECAUSE OF PRECOHHFRCIAL T H I N N I N G ,
DOH +
T O T AL CODOH
AGE HEIGHT
YEARS FEET
2 9 . 5 62 . 2
30
63.6
•
HEAN
OBH
I NCHES
e. oo
MEAN
G l/
SO FT
• 349 1
HEAN
VOl
CU F T
�.61
MERCHANTABLE
CUT
HERCH LEAVE
6. 1 1
e . o&
8.13
. 35 6 5
. 3544
, 3&06
9,oo
SUH GROSS
SUH HERCH
SUH OF CUT
8 . 06
STAND
C O MPONENT
F I!lST POSS
8 . ee
9, 0 E
.
'IOL IGif.
R AT I O •
2 4 . && •
YOlUHE
ACRE
PEF>
4-INCH
5•INCH
6-I NCH
CU F T
C U FT I Nfl 1 1 4 ?j SC R I B ?j
3456
2 5 , 09
25 . 0 5
25, 1 1
3&14
1203
24 1 1
3 1 79
1 05 &
2 1 23
1 �502
4808
9695
7655
2517
5 1 38
•
36 1 �
36 1 4
1203
3 1 79
3 1 79
1 056
1 4502
1 4 50 2
lt 8 0 8
7 & 55
7655
2517
•
5078
1 476
360 2
47:34
1 3 57
3377
251�0
6948
1 6 1 92
1 7 947
461t9
1 3 298
6280
6280
2678
579 1
579 1
24 1 3
29948
29948
1 1 756
2 0 4 €4
2 04 6..
7166
•
•
.
•
85.9
MERCHANT ABLE
CUT
HERCH L E A VE
SUH GftOSS
SUH HERCH
SUH OF CUT
I O . It 8
9.42
1 1 .05
•5989
. 48 3 6
6662
•
19.07
's.o3
21 .42
3 1 . 8 .. .
3 1 . 09 •
32, 16 .
•
•
6 . 66
4599
VOl GROWTH
60
60
•
•
•
G l/
P E R CURRENT
P R ICE
PfR
ACRE
$
ACRE SC F T
40 1 . 7 1 4 0 . 2
TREES
4 0 1 . 7 1 44 . 0
1 35 . 4 lf8 . 0
266,3 96. 0
135.4
D I SC
PRICE
$
CUH
P R ICE
$
1 1 48
30 2
1 1 48
1 503
312
1805
1 07 1
1 6 84
1 1 48
302
144.0
1 4 4 . tl
44 . 0
2666
V O L GROWTH
40
•
•
•
•
266,3 I 59, 5
9 8 . 1 �7 . 5
t6e.t 1 1 2.0
r
269 ·
55 .
.
207 , 5
207 . 5
233.6 9 5 . 5
•
1 16.0
MERCHANT ABlE
14.88
2 0 74
48.78
4 0 . .. 0
•
82n t
79 1 7
49206
1t l 00 5
1 16,0
HARVEST
1 4 . 8 8 1 . 2074
48.7 8
.. 0 . 40
•
820 I
7917
4 9 2 TI 6
It I
0 87 9
1 0 879
1 0679
1 0330
1 0330
1 03 3 0
60962
60962
60962
.. 8 1 70
4 8 1 70
.. 8 1 70
••
•
•
•
005
1 68 . 1 2 0 3 . 0
6 151
1 66 . 1 20 3 . 0
GRAND T O TA l S
SUH GROSS
SUH MERCH
S U H OF CUT
l/
y
Basal
• I
•
1 1.67
•
•
•
•
298 . 5
298 , 5
4 0 1 . 7 2911. 5
a re a .
B o a r d f ee t .
21
TAB L E
�ROGRAH
OFIT
D O UGLAS-F I R M A NAGED YIELD TABLI'S
S ITE I N O E X= I ... O o O ( I 00-YEAil BASIS)
T H E CONTROL C A R D SPEC I FI E S THAT
D IAMETER O F T H E �ERCHA NTABLE P A R T O F THE STAND A T T H E FIRST POSS IBLE CO�MERCIAL THI N NI N G I S e . o o INCHES ,
THE M I �IHUH MERC H A NTABLE O B H I S 6 , 0 0 INCHE S ,
T H E S T A N O HAS PRECOM�ERC IALLV T H I N N E D A T AGE
1 0 '!' E A R S ,
THE THI N N I NG I N T ERVAL I S C O NTROLLED BY H E I GHT GROWT H , THERE HILL BE APPROX I M ATELY 2 5 . 0 FEET OF
HEI GHT GROHTH BETHEEN COMMERC I AL T H I N N t NG S ,
NUMBER O F COMMERCIAL T H I N N INGS= 2 .
TOTAL AGE A T HARVEST= 6 0 V E AI< S o
HARVEST STUMPAGE=$ 1 5 0 . 0 0 PER T HOUSAND BOARD FEfT SCRie�ER .
T H I N N I N G STUMPAGE= $ 1 20 , 0 0 PEil THOUSAND BIJARD FEET SCRIBNER ,
D I SCOUNT RATE= , 06 0 0 ,
SITE I NDEX HAS A D J USTED T O 1 47 . 6 BECAUSE OF PRECOHHERCIAL T H I N N I N G ,
OOM +
TOTAL COOOH
AGE , HEIGHT
YEARS F EET
29 . 5 6 2 . 2
STANO
COMPONENT
FIRST P OSS
63,6
30
H E AN
DBH
I NCHES
a.oo
MERCHANTABLE
CUT
HEfiCH L EA V E
6. 1 1
8 , 06
8.13
SUH GROSS
SUH "EfiCH
SUH OF CUT
8o06
HEA N
GY
SO FT
. 34 9 1
HEAN
VOL
CU FT
8.61
3585
, 3544
.3606
9.oo
•
e,ee
9o06
"
VOL/Gll,
RATIO •
2 4 , 66 "
VOLU ME
ACR E
PER
It-INCH
N
6-I NCH
CU FT
CU FT I �
4 Y S C R I BY
'1458
2 5 . 09
2 5 . 05
25, I I
36 1 4
1203
24 I I
3 1 79
I 056
2 1 23
1 4502
4808
9 6 95
7 6 55
25 1 7
5 1 38
36 1 4
36 1 4
1 20 3
3 1.7 9
3 1 79
I ll 56
1 4502
1 4502
4808
7655
7655
2517
89.7
MERCHANT A B L E
CUT
HERCH LEAVE
SUH GROSS
SUH HERCH
SUH OF CUT
•
•
"
.
•
VOL GROWTH
42
•
1 0.80
9.60
1 1 .55
, 63 6 5
, 50 28
. 72 7 0
20.97
16. 1 5
24. 2 3
3 2 , 94
32, I I
3 3 . 33
8 .7 8
1 16,0
MERCHANTABLE
60
1 16.0
HARVEST
•
•
"
' 0 1 . 7 l ltlt . O
1 35 . 4 .. a . o
2 6 6 . 3 96 . 0
•
135.4
3172
•
558�
1736
3848
5231
1 604
3628
28305
8 3 44
1 99 6 1
2 0 650
5703
1 49 4 8
•
•
6 268
6288
2660
33 113
33 1 1 3
1 3 1 52
23 1 67
2 3 1 67
8219
•
•
6786
6786
29"38
•
G l/
PER
PER
ACRE
ACRF S O FT
4 0 1 .7 1 49 . 2
TREES
•
"
VOL GROWTH
60
� t ��
•
•
•
ll
?j
22
Basal
area ,
Board fee t .
DISC
PRICE
CUH
PRICE
""8
302
1 148
302
""8
��� 9·e
681t
1 53 9
31t0
1 84 1
5990
1 043
1 685
'!
'
1 44 . 0
l 41t . O
4! 8 . 11
266, 3 1 6 9 . 5
1 07 . 5 54. 0
158.8 II 5,4
217.5
217.5
21t 2 . 9 1 0 2 . 1
4094
1 5 . 0 7 1 . 23 7 9
50. 0 1
4 0 . 40
•
7942
7669
477 8 0
39931
•
158.8 196o6
1 5 . 0 7 1 . 2 37 9
50. 0 1
4 0 , ItO
•
7942
7669
477 8 0
39931
•
l58.e 196,6
•
1 0 880
1 1l8 8 0
I 0 88 0
1 03 2 9
1 0329
6 0 932
6 0 932
60932
4 8 1 51
4 8 1 51
4 8 1 51
•
GRANO TOTA L S
SUH GROSS
SUH HERCH
SUM OF CUT
CURRENT
PRICE
$
I I o67
•
•
I U J2q
298. 6
29 8 . 6
4 0 1 .7 298 . 6
TA B L E
PR OGRAM
D O U Gl A S - F I R
O f' IT
� A N A G E O V I EL O l A Bl'ES
S I T E I N O E X= I � O , O ( I C 0-'I'EAR B A S I S I '
THE CONTROL CARD S P EC I F I E S T H A T
O I A�ETER OF T H F T O T AL S T A N O AT T HE F II! S T P O S S I B L E COHHERC I A L T H I NN I N G I S
6 o 0 0 INC HE S ,
T H E H I N I H U H MERCHANTABLE O B H I S
I 0 VEAR S ,
T H E S T A N O H A S PRECO�HERC I A L L V T H I N NED AT AGE
T H E T H I N N I NG I N T E R � A l I S
1 0 YEARS ,
N U H B E R OF COHHER C I A l T H I N N I N G S=
z.
60 Y E A R S ,
TOTAL AGE A T H A R V EST=
F E R T i l i Z E R ! N I T R O G E N 2 0 0 L R / A C R E I I S APPLIED A T EACH C C HHF.RCIAl TH I N N H G ,
1 5 0 , 0 0 PER T H O U S A N D BOARD FEET S C R I B N E R ,
H A R V E S T STUMPAGE=$
1 2 0 , 0 0 P E R T H O U S A ND B O A R D F F E T S C R I BNEP ,
T H I N N ING STUMPAGE=$
D I SC O U N T RATE= . 0 6 0 0 ,
SITE
OOH •
T O T AL CODON
AGE
HE I G H T
FEET
YEARS
29.5
62o2
30
63,6
I NO E X H A S A D J U STED T O
STANO
C O M P O NENT
F IRST POSS
HERtHA NTAOL E
CUT
HERCH L E A V E
SUH GROSS
SUH HfRCH
SUH O F CUT
VOL
40
88.2
e . oo
Bol l
8 , 06
8ol3
HEAN
G l/
SQ FT
• 3491
• 3 5 85
• 3544
, 3 6 06
OFCAUSE
SUH G R O S S
SUH HERCH
SUH OF CUT
I NC H E S ,
O f' P R f C O H H E R C I A l T H I N N I N G ,
Z
HE A N
VOl
C U FT
8.6 1
IIOl/Gl
RATIO "
2 4 . 66 •
VOLUME
PfR
ACRE
•
" - HC H
6- I NCH
5 - INCH
CU F T
C U FT
I NTL II .. g_; SC R I B £/ •
•
��58
9o00
8.88
9 . 06
25 . 0 9 •
25,05 •
25, I I •
36 1 4
1 20 3
24 1 1
3 1 79
I D56
2 1 23
l lt 5 U Z
4808
9695
7655
2517
5 1 38
36 1 4
36 1 4
1 20 3
3 1 79
3 1 79
1 056
1 '< 5 0 2
1 45 0 2
4808
7M5
7655
2517
•
•
8o06
•
.
•
G l/
TREES
PER
CURRENT
ACRE
PR ICE
PER
ACRE
SG FT
$
40 I. 7 140 . 2
It O l o 7
1 35,4
266 . �
1 44 . 0
48. 0
96.0
135,4
1 4 .. . 0
1 4 ... 0
48,0
1 0 .74
9 . 56
1 1 . 44
. 6289
o 49 9 0
o 7 1 44
20 o 4 5
15.82
23 . 4 9
32, 5 1
3 1 . 70
32.88
•
•
•
•
8 , 75
5 1t 4 ..
1 67 1
3773
5 09 4
1 542
1552
27399
7963
1 94 1 6
1 9879
5 4 2ft
1 4 .. 5 5
266 , 3
105,7
1 60, e
1 67 . 5
52o7
1 14.7
6647
66 .. 7
2874
6 1 50
6 1 50
2599
3 2 2 07
3 22U1
I 279 1
2 23 9 5
2 23 9 5
7941
24 1 , I
215.5
215,5
100,7
60
1 2 0 . 1,
MERCHANTABLE
1 5 . 47
l o 3058
54. 20
4 1 .51
60
1 20 , I
HARVEST
1 5,47
l o 3 0 58
54 , 2 0
4 1 . 51
•
•
CUH
P R ICE
$
1 1 48
302
""8
2982
651
1 66 5
363
1 9 67
671 9
I I TO
" "e
302
t
209,7
•
493�
GR OWTH
D I SC
PRICE
;�·
3033
G R O WT H
MERCHANTABLE
CUT
HERCH l E A � E
VOL
HFAN
ll B H
INCHES
1 47,6
e , oo
8706
8424
5 3 1 75
4 4792
160,6
8706
8424
5 3 1 75
4 4792
1 60 , 6 2 0 9 . 7
t 1 58 0
1 1 580
1 1 580
1 1023
l l n23
"0 23
6 5 9 66
65966
65966
5 2 7 33
527n
5 2 nl3
1 8 35
GRANO TOTAl S
SUH G R O S S
S U H HERCH
SUI1 O F CUT
ll
y
Basal
•
•
l l o90
•
•
310.5
310,5
40 1 .7 J I D , 5
area ,
B o a rd fe e t .
23
TABLE
PROGRAM
D O UGLA S-FIR
Of IT
� A N A G F. D Y I ELD T A B U S
SITE
I N D E X= I � O , O
I I � 0-'f E A R B A S I S)
T H E CONTROL CA�D S P EC I F I E S T H A T
T H E F I R S T COMHERCIAL T H I N N I N G �ILL OCCUR W H E N T O T AL AGE I S
'+0 V E A R S o
D I A M E T ER O F T H E �ERCHANT A B L E P A R T O F T HE S T A ND A T T H E F I R S T P O S S IBLE C O M H ERCIAL T H I N N I N G I S
6 o 0 0 INCH£S ,
T H E H I � I "U H M E R C H A N T A B L E D B H I S
1 0 VFAR S ,
T H E S T A N O H A S P R E C O HHERC I A L L l T H I NN E D A T A G E
T H E T H I N N I N G I NT E R V AL I S
1 0 YEARS,
2o
N U H B E R O F C O H H E R C I AL TH I N N I N G S=
T O T AL A G E A T H A R V E S T =
60 YEARS.
1 5 0 o 0 0 P E R T H OU S A N D B OA R D f E E T SCRIBNER •
H A R VE S T S T U � P A G E = $
1 2 0 , 0 0 P E R T H O U S A N D BOARD f E E T SCR I B N E R ,
T H I N N I NG S T U M P A G E= $
D I SCOUNT RATE= • 0 6 0 0 ,
SITE INDEX HAS
OOH +
TOTAL COOOH
AGE
HE IGHT
YEARS
FEET
62,2
29 o 5
40
85,9
A D J U S T E D TO
1 �7 . 6
BECAUSE
1 02,9
PREC O H H E RC I A L T H I N N I N G ,
Z
•
HEAN
OBH
I NC H E S
6,00
HEAN
G /
l
SQ FT
o3491
�EAN
VOL
CU F T
e.6 1
V OL / Gl
RATIO •
2 4 . 66 •
PfR
VOLUHE
ACRE
4-HCH
5 • I NCH 2 / &• I NCH
CU FT
I�Tl 1 1 .. - SC R I B £/
cu fT
�458
MERCHA N T A B L E
CUT
HERCH L E A V E
9o 47
6 . 6�
9o64
• 4892
. 4 2 63
. 5 282
1 5.56
13.3�
1 Eo9E
3 1 .64
3 l o 30
32, I I
6257
2050
.. 2 0 7
5752
1 8 63
3869
29331
92� 1
2 0 1 00
1 9560
5 8'4 0
1 37 4 0
SUH GROSS
SUH �ERCH
SUH OF CUT
8.8�
6257
62 5.7
2050
5752
5752
1 8 63
2933 1
2933 1
9 23 1
1 9 580
1 95 8 0
5 64 0
STANO
COHPONENT
FIRST POSS
MERCHA N T A BL E
CUT
HERCH L E A V E
SUH G R O S S
SUM HERCH
SUH OF CUT
VOL
•
•
.
•
..
•
VOL G R O W T H
50
OF
1 1 .50
I o. 0 0
1 2. 24
,72 1 0
. 54 5 3
o 8 1 71
26.46
1 9 .47
30.32
36 ,73
�5.70
37. 1 0
•
•
•
8 o 0 0 INCHES ,
/
Gl
CURR E N T
TREES
I' E R
P R ICE
,PER
ACRE
$
S O FT
ACRE
4 0 1 .7 1 � 0 . 2
�0 l o 7
153.7
2�8 . 0
196o 5
6So5
l 3 l o ll
1 53.7
196o5
1�6.5
65o5
2 .. 8 . 0
ll 7 o 7
l 60 o 3
176o8
47o8
131.0
2 4 1t o 3
2�4 . 3
1 1 3. 3
•
2362
•
6566
!707
�86 1
6 2 29
1 597
�632
3 55 66
8 7 07
26660
27 1 8 1
6 2 52
2 0 930
86 1 9
86 1 9
37 56
8092
8092
3�60
� ft 7 97
�4797
1 7 937
330 2 1
3 30 2 1
1 20 9 1
•
2� 1 . 4
•
1 60 , 3
1 7 2.7
1 60 .3
1 7 2.7
4,0 1 . 7
2a6. 1
28 6 o I
U6o l
•
.
9 o 28
•
•
•
60
1 1 6.0
MERCH A NT A B L E
l ft o 0 5
l o 0 773
43 . 5 2
�0.40 •
60
1 16.0
HARVEST
1 4 . 05
l o 0773
43.52
40.40
•
6979
6726
� 1 559
3 fo 2 0 2
6979
67 28
.. 1 5 59
34202
I 0736
I 0736
1 0 1 88
1 0 1 86
I 0 1 88
59�96
5 9 4 96
5 9 4 96
� 6 294
lt 6 2 9 1t
�6294
G R A N O TOTALS
ll
y
24
Basal
a r e·a .
Board
fe e t .
CUH
PRICE
2 937
2937
4 07 7
750
2 2 77
fo l 9
2977
5130
1600
27 1 9
2 93 7
701
r·
.
.
s
70 1
$
2118
GROWTH
SUH GROSS
SUH HERCH
SUH O F CUT
D I SC
PRICE
•
1 1 .�3
•
•
1 07 3 6
•
TAB L E 8
PROGRAM
1l0UGL A S-FIR
ll F I T
fl A N A G E D Y I EL D T A BU'S
S I T E I N DEX= I � D . O ( I U D-Y E A R l! A S I S )
T H E CONTROL CARD SPEC I F I E S THAT
T H E M I N I � U H MERCHANTABLE D B H I S
6 , D O INCHES,
T H E STAND HAS PL A N T E D ,
T H E T H I N � I N G I NT E R V A L I S
I 0 YEARS,
N U H B E R O F COHHERCIAt T H I N N I N GS=
2.
60 YEA R S ,
TOTAL AGE AT H A R V E S T=
H A R V E S T STUMPAGE=$
1 5 0 , 0 0 P E R T HO U S A N D l!OARD F E E T SCRIBNER,
T H I N N I NG STUMPAGE=$
1 2 0 , 0 0 PER T H O U S A N D B O A R D F E E T SCR I B N E R ,
D I SCOUNT RATE= o 0 6 D O .
S I T E INDEX
STANO
C O H P O � ENT
FIRST PUSS
61.0
MERCHANTABLE
CUT
HERCH L E A V E
SUH GROSS
S U H !t E A C H
SUH O F CUT
VOL
39
TO
1 47 , 6
BECAUSE THE STAND
WAS PLANTED,
83.9
HERCHANTABLE
CUT
HERC H L E AVE
VOL
MEAN
HEAN
INCHES
8,oo
S O FT
• 3491
!lEAN
VOL
CU FT
8 . 27
8ol5
6.09
8ol8
,3621
. 3 566
.3652
e.8 o
6 . 6 it
8o88
OBH
G l/
RAT IO •
2 3 , 69 •
..
VOLUME
PER
ACRE
4- INCH
•
6 - I NCH
5- INCH
cu F f
C U FT
INTL 1 / 4 ?j S C R I Il£/ •
332 1
•
TREES
PER
CURRENT
PER
ACRE
PRICE
S Q FT
ACRE
$
40 1 . 7 1 4 0 . 2
2 4 . 28 •
24. 2 3 •
24 o l l •
3534
1 175
2159
3 1 07
I031
2076
1 4 1 07
4668
94"39
7 3 84
2" 1 5
4969
"0l o7
1 36 , 0
265o7
145.5
48. 5
91.n
3534
3534
1 1 75
3 1 07
1 1 07
I OJ I
1 4 1 07
1 4 1 07
.. 668
7 3 84
7 3 8 '+
24 1 5
136,0
145 . 5
1 45 . 5
48.5
265.7
99.9
1 65 . 8
161 . 6
lo 8 . ll
1 12.8
•
23 5 . 9
21o, I
210.I
97o3
•
165.8
208 . 7
l 65o8
208.7
Z
VOL/G l
•
•
•
8 .0 9
GROWTH
SUH G R O S S
S U H HERCH
SUH O F CUT
•
•
•
D I SC
PRICE
CUH
P R IC E
1 1 08
290
I I 08
290
I I 08
2665
5 5 9�'
1 � 88
312
1 778
6372
1 0 1t7
1 64 9
t
I Oo5&
9o46
1 1 . 17
.&083
.488�
6805
•
1 9. 0 2
14.90
2 1 . 50
3 1 . 26
30.51 •
3 1 .59 •
5052
1 '+ 8 8
l564
\7 0 9
1 3 68
3"3 4 1
2 '+ 8 9 5
69'1'9
1 '1' 9 1 6
1 7 766
4660
1 3 1 06
•
6228
6228
2 6 64
5740
5 74 0
2199
29563
29563
1 1 6 47
20181
20181
7074
8 .70
GROWTH
"
48 &9
1 16.0
MERCHANTABLE
15.19
l o 2589
50.86
ft 0 o 4 0
•
843"3
8 1 44
�0748
4 2478
60
1 1 6. 0
HARVEST
15.19
l o 25 6 9
50.8&
4 0 . 40
•
81t31
8 1 44
5 07 4 8
4 24 7 8
1 1 0 97
1 1 0 97
1 1 097
1 0 543
1 0543
1 0 543
6 2 396
6 2396
&2196
49552
49552
4 9 552
•
TOTALS
SUH GROSS
SUH HERCH
S U H OF C U T
ll
Basal
?j
B o a rd f e e t ,
'
2694
•
60
GRANO
G .1f
•
D O H ..
TOTAL CODOM
AGE
H E I G HT
YEARS
FEET
26 . 3
59 . 1
29
HAS ADJU STED
•
l l o82
•
•
•
306.0
306.o
.. 0 1 . 7 3 0 6 . 0
area ,
25
TABLE
PROGRAM
DOUGLAS-FIR
OFIT
�A N A G E O V I E L O T A S L E S
S I T E I NO E X= I � O . O
T H E C O NTROL C A R D S P EC I F I E S T H A T
! 1 " 0 �-VEAR B A S I S !
D I A M E T E R O F T H E T O T A L ST ANO A T T H E F I R S T P O S S I B L E C O H H E RC IA L T HI N N l � G IS
T H E H I N I H U H M E RC H A N T A B L E O B H I S
6 . 0 0 INCHES,
THE STANO H A S P L A N T E D .
T H E T H I N N I NG I NT E R V A L I S
1 0 YEARS ,
N U M B E R OF COHHERC I A L T H I N N I N G S=
2.
T O T Al AGE AT H A R V E S T =
6 0 V E A!l S .
HARVEST STUHPAGE=t
1 5 0 , 0 0 P E R T H O U S A N D B O A R D F E £T SCR I B NE R .
T H I N N I N G S T U HP A G E= $
1 2 0 . 0 0 P E R T H O U SA N D BOARD F E E T S C R I S N E R ,
D I SC O U N T R A T E= . 0 6 0 0,
STANO V O L U H E G R O W T H W I L L BE INC R E A S E D
2 0 , 0 PERCENT STARTING A T PLANTING.
SITE I ND E X H A S A D J U S TED T O 1 6 0 , 8 T O S I HU L A T E T H I S G R O WTH C H A NG E ,
S I T E INDEX H A S ADJUSTED T O
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TOTAL C O O O H
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H E IGHT
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I NC H E S .
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COMPONENT
FIRST POSS
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V O L GROWTH
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26
*GPO-I 9 7 8 - 7 9 6 · 5 0 4
The m1sswn of the PACIF I C NORTHWEST FOREST
AND RANGE EXPERIMENT STATION is to provide the
knowledge,
technology,
and alternatives for present and
future protection, management, and use o f forest, range, and
related environments.
Within
this overall mission,
the Station conducts and
stimulates research to facilitate and to accelerate progress
toward the following goals:
1 . Providing safe and efficient technology for inventory,
protection, and use of resources.
2. Developing and evaluating altemative methods and
levels of resource management.
3. Achieving
consistent
optimum
with
sustained resource productivity
maintaining a
high
quality
forest
environment.
The area of research encompasses Oregon, Washington,
Alaska, and, in some cases, California, Hawaii, the Western
States, and
the Nation. Results of the research are made
j
available promptly. Pro ect headquarters are at:
Fairbanks, Alaska
Portland, Oregon
J uneau, Alaska
Olympia, Washington
Bend, Oregon
Seattle, Washington
Corvallis, Oregon
Wenatchee, Washington
La Grande, Oregon
Mailing address: Pacific Northwest Forest and Range
Experiment Station
P. O. Box 3 1 4 1
Portland, Oregon 9 7208
1-
The F O R EST S E R V I C E of the U.S. D e partment of Agriculture is ded icated
to the p r i n c i p l e of m u l t i p l e
m a nagem e n t of the N a t i o n 's forest resources
for susta i n ed y ie l d s of
water, forage, w i l d l ife, and recreation.
coop� ration w i th the States and p r ivate forest
T h ro ug h forestry
owners, and m a n agement of the N a t i o n a l Forests and National G rass l a nds, it
strives - a s d i rected
Congress - to provide i n creasi ngly greater service to
a grow i ng N a t i o n .
T h e U .S. Depart ment
Agriclll t u re < i s an Equal Opport u n ity E m ployer.
programs w i l l be
e q u a l considera t i o n
Appl i cants for a l l ' � � � �+r�
without regard to race,
orig in.
THE DFIT MANAGED STAND S IMULATOR AND
SOME ESTIMATED EFFECTS OF THINNING ON YIELD
by
Donald L . Reukema
USDA Forest S ervice
Pacific Northwest Forest and Range Experiment S tation
Olympia , Washington 98502
AB STRACT
This paper supplements publ icat ions on a Douglas-fir managed s tand s :l.mul.ator and
effect s of thinning on yield of Douglas�fir by highlight�ing some of the informa­
t ion presented therein . It g ives an overview of what DFIT (Douglas-f:l.r. in teJ::I.m
tables) does , concepts on which DFIT is based , and effects o f applying s elected
thinning regimes .
INTRODUCTION
��·· '
Ob servat ion and research on yields of managed Douglas-fir stands have given us
many bits of knowledge , but--unt il recently--no unified p ictur e . We assembled
these fragmented b its of knowledge into a conceptual model of s tand structure and
development , which provides a basis for extrapolating results of stud ies to con­
d itions which have not been direc tly observed . Resul ts of studies were balanced
against d evelopment of natural stands , and against one another , to derive rela­
t ionships b etween various stand parameters and to insure consistency .
We then constructed a stand simulator (DFIT--Douglas�fir interim tables) which
e s t imat e s expected stand development and yield , wj_thin specif ied limitat ions
about stand characteristics and treatment regimes . Within the l imitations of our
model , estimates o f merchantable yield over a range o f s i t e quality, merchanta­
b il ity l imits , and thinning regimes appear cons is tent and provide good e s t imat es
o f relat ive gains from thinning . Yields e s t imated by the simulator are extrapo­
lated far beyond the available data base .
Two pub l ications are t ied to this effort . "Douglas�fir Managed Yield S imu l a tor-�
DFIT User ' s Guide" (Bruce et al . 1 9 7 7 ) explains how to use the s imulator and
describes it s operat ion in enough detail that the reader can make adj ustments .
"Effects of Thinning on Yield of Douglas-fir : Concepts and . Some Estimates
Obtained by S imulat ion" (Reukema and Bruce 1 9 7 7 ) discusses concepts of stand
development and effects of thinning , provides guidelines for thinning , and''-"-%
summarizes current expectations .
,,_,
This paper is intended to supplement the forego ing publication s by highlighting
some o f the information presented therein . It gives an overview o f ( 1) what DFIT
does , ( 2 ) concepts on which DFIT is based , and (3) resul t s of applying selected
thinning regimes .
THE DFIT SJMULATOR
Purpose
DFIT is a computer program wh:i.ch simulates s tand development and tabulates th e
results of the simulation . It i s designed ' to provide estimates for "average 11
stands and to produce ntypical" yield tables for a given s ite index and treatment
regime . DFIT is no t directly applicable to simulat ing , the development of a p ar­
t icular stand . It can aid one in approximat ing expected d evelopment of any s tand ,
however , when used in conj unct ion with concept s discussed by Reukema and Bruce
(1977) .
DFIT describes stand characteris tics at t ime o f each entry � while allowing a
choice o f thinning regimes and merchantability standards . It enables one to
compare characteristics o f managed s t ands with tho se of corresponding unmanaged
natural stand s .
Advantages and Limitations
A maj or advantage of DFIT is its flexibility in the choice of minimum merchantable
d . b . h . For unmanaged natural stands and s t ands receiving only commercial thin­
ning > DFIT s eparate s described stand characteristics into corresponding merchant­
(For st'ands which receive preconunercial
abl e and submerchantable component s .
thinning , we assume that all trees will at tain merchantable size·.. ) The program
also allows the user to select alternat ive thinning regimes .
}
,�·· '
DFIT assumes that the stand is normal at the t ime o f the first entry and that it
will develop in the normal manner if left untreated . Thus , it is d irectly appli­
cable only to pure Douglas-fir stands which have the assumed s tand s tructure .
Another l imit a t ion of DFIT is that the precommercial thinning routine is effective
only for thinning prior to age 20 and to stand den s ities of about 150 to 4 0 0 trees
p er acre . DFIT also restric t s the earliest age for commercial thinning .
DFIT Output
I
·,
For each scheduled entry , the program prints out s t and summary tables which detail
the comp o s it ion of the stand . S tatistics given include :
(1) t ime o f entry ,
expressed a s total stand age and as average height of dominant and codominant
tree s ; ( 2 ) average-tree descriptors-�d . b . h . , basal area , cubic volume , and cubic
volume : basal area ratio ; and (3) per acre descriptors--number of trees , basal
area , t o t al cubic volume , cubic volume to a 4-inch top , Int ernat ionaJ. board-foot
volume , and S cribner board�foot volume .
(1) t o tal s tand , sub�
S t and components to which these statist ics apply include �
merchantable component , and merchantabl e component before · cutting ; ( 2 ) cut trees
(all merchantable) ; (3) merchantable component and total s t and after cutting ; and
( 4 ) cumulated yields for all trees , merchantable component , and cut trees . The
user can also get a managed s t and summary in which much o f this detail i.s d-e"feted .
I t shows only the total s t and and merchantable component before each cutting . �h
The corresponding natural s tand table shows :
( 1 ) live stand at 1:i.me of each
entry in terms of to tal stand , submerchantable component , and merchantable
component ; and ( 2 ) mortality during period between entries for submerchantable
component and merchantable component . One can also get only the natural s tand
tab le s , if desired .
l
\
\
I
Controlled Input
Because of the. a ssumpt ion that we are . d ealing with 8.vera,ge
DFIT s imulator requir e s only minimal input information·�
only :
(normal )
s tand s >
the
· Required inptlt includ es
(1) s ite. index� ( 2 ) . minimum merchantabl e d . b . h .Y , and (3) p r in tout�age
contro l s .
For s tand s that are thinned ,
c ommerc ial thinnings and f inal harve s t .
the age a t preconnne rc ial thim1.ing ,
nings and f inal harve s t ;
these printout ages are the ages a t
For the s e s t and s , the u s er mus t enter
i f done , and a s chedule for commerc ial th:i.n­
this schedule may b e specified in one of s everal ways .
Other cont r o l s enable the user t o include o ther assumpt ions ,
output ,
or b o th .
s p e c ify d e s ired
Assumed Input
As sump t ions regarding s t an d d evelopment d e s ignat e the stand s tructure a t t ime o f
f ir s t commercial entry .
input .
S ome a s p e c t s of
They also enable. use of a l t ernat ives for contro l l ed
the th inning regime are also a s sumed , rather than b eing d e s ig­
nated by contro lled input :
at the next entry)
footno t e
1) ;
(2)
( 1 ) number of trees after precommer c :Lal thinning ( oJ:"
i s a fun c t ion of the minimum merchantab l e d . b . h .
the first commerc ial thinning �
( s ee
·
if not o therwis e specified ,
also a func t ion of the minimum merchantable d . b . h .
( s ee foo tno t e
1) ; ( 3 ) the
is
d / D ratio ( i . e . , ratio o f the average d . b . h . o f cut trees t o average d . b . h . o f
merchant ab l e trees b efore thinning) i s a funct ion o f average d . b . h . and minimum
merchan t ab l e d . b . h . ;
and
( 4 ) the r e sidual s t and after each thinning is a func t ion
of numb er and s i z e of trees b efore thinning and of the d/D rat i o .
these lat ter two a s sump t ions can be changed .
Equations for
THE CONCEPTUAL MODEL
Concep t s built into DFIT , and on which our yield e s t imat e s are b a s ed ,
normal s t and s .
That i s ,
apply to
it i s as sumed that s t ands are normal at the t ime o f the
f ir s t entry and that they will develop in the normal _ manner i f l ef t un thinned .
Once one fully under s t ands the s e concepts as they app,ly to
the normal s tand
s itua t ion , he can extrap o l a t e them to various non-normal s ituat ions .
The concep tual model has thr e e maj o r elemen t s :
(1) s t ructure , mortal ity , and
growth of natural s t and s ; (2 ) sour c e s of gains � and l o s se s s from thinnin g �
relative to the natural s t and ; and (3) th inning regimes .
Time d o e s no t p ermit:
a d e t a iled d i s cuss ion of concep t s here ,
so I must
urge you to read , and s tudy , Reukema and Bruc e ' s
cover them very br iefly.
(19 7 7 ) repor t .
I
S t and S t ruc ture and Development
Concep t s relate p r imarily to pattern of development ,
opment .
as opposed t o rate of devel­
This pat tern i s largely ind ependent of s ite quali t y .
l/ Or an average d , b . h .
at f ir s t p o s s ib l e corr�ercial thinning , from which this
minimum merchantab l e d . b . h . · ;i s calcula t ed .
Rate of develo pment is appropr ia tely shown by conventional curves o f / variabl e s
s u c h a s average d . b . h . ? number of t r e e s per acre , and basal ! ar.ea. p ex a c r e a s
The correspond ing pattern of development is si'lown by exp r e s s ­
func tions o f a g e .
ing average d . b . h. , numb er o f tree s , and basal area rela t ive to o n e ano ther .
Total numb er o f trees and basal area p e r acr e , and the con�espond ing average
d.b .h. ,
tell l it t l e about s t and s truct ure , however .
Therefor e , · we have al s o
defined corre sponding tree;... s i z e· d i s t r ibut:i.on and appro::!Fimat e d is tribution among
c rown class e s .
This enabl e s · us to a s s e s s development of two typ es o f s t and
components which are of int erest to us in regard to managed s t and s :
numb ers of largest trees and ( 2 )
l a t t er includes. ingrowth and mor tal ity .
relat ive t o :
(1) f ixed
trees · larger than any sp e c i f ied d . b . h .
The
We a s s e s s development of these components
(1) one ano the r , (2 ) the t o tal s t and , and (3) . crov.m c l a s se s .
Development of f ixed numb er of large s t trees is pertinent to es t imat ed gains in
Development of trees larger than s p ec if ied d . b . h . ,
tre.e. s i z e due to thinning .
along with development o f the · total s t and , forms the basis for s eparat ing the
s t and into merchantable and submerchanta.ble componen t s .
the b a s i s for defining ' ' crop trees . "
Together , thes e f o rm
This defined s tructure and d evel opment of normal s t ands provid e s a basis f o r
d e s crib ing e f f e c t s of thinning o n s tand s t ructure and d evelopment .
I t al s o
provid e s a bas.i s for evaluating effect s o f non-normal stand s truc tur e .
S ourc e s o f Gain
In natural s tand s , many trees never. a t tain merchantable s i z e .
do a t t ain merchantable s i z e sub s equentTy die .
r· .
Many o f tho s e that
With commercial thinning , we can harve st mo s t o f these merchantable trees that
would no rmally die .
We usually harve st many of them well in advance of when
they would normally die .
Also , we u sually harve s t many trees which would
o therwi s e be pre sent at t ime of f inal harve s t .
Thus , part of this gain from
preventing lo s s es to merchantab l e mortality is o f f s e t by reduced growth p er
acre b ecause o f incomplete o ccupancy o f the s it e .
With. pre commercial thinning , we can concentrat e all sub s e quent growth onto trees
which. will a t t ain merchantab l e s i z e· . ·
We el iminat e compet i t ion from non-crop
trees and grow the crop tre e s to merchantable s iz e· more rapidly .
of growing space can al s o re sult in improved height growth .
Early control
Thinning Regime
Maj o r considerations regard ing the thinning regime are :
(2)
r e s idual gro>ving spac e ,
and
(3)
( 1 ) t iming of thinning ,
s e l e c t ion of l eave trees and trees to cut .
For precommerc ial thinning :
Time so as to :
- max1m1z e advantage of improved growth rat e s .
- facilitate s el ect ion of high�qual ity l eave trees .
min imiz e p o s s ible sub s e quent damage to trees .
Space trees widely enough that ;
all trees will reach merchantable size .
t re e s will s t ill b e vigorous at t ime of next entry .
Se lect to leave :
b e s t quality tree s .
- trees of fairly uniform s i z e among cont iguous trees .
For commercial thinning :
Time :
f ir s t thinning to capture merchantable inortal i ty and maintain
s tand vigor .
- int erval b etween thinnings to maintain s tocking l evel within d e s ired l imi t s .
l a s t thinning to have a fully s t o cked s t and.�/ at f inal ha1:vest .
Space trees so that :
- all will have ample room t o grow until the next entry .
- occupancy of the s i t e will be fairlyj well r e t a ined .
Se lect to leave :
good qual ity dominant and codominant trees which will respond to release
received ,
if any .
- intermediate trees which are expected to grow more and to not int erfere
wi th growth o f dominant and codominant tree s .
Se lect to cut :
;-:-·
- merchantable trees not exp e c t ed t o live unt il the next entry .
. ·
'
- poor qual ity trees .
- trees which should be removed to give o thers ampl e growing spac e .
EFFECTS OF THINNING
Result s of applying s elected thinning r egimes have b e en examined in t erms o f :
( 1 ) number and s i z e of t r e e s harve s t ed and their . di s t r ibut ion over t ime; and
( 2 ) amount of usable volume harve sted and i t s d i s t r ibution over t ime , by var ious
merchantab ility s t andards .
Numb er o f Harve s t ed Trees
The t o t al number o f trees harve sted
( in thinnings p lu s f inal harves t ) depends on
(1) the minimum merchantab l e d . b . h . and ( 2 ) how early the f ir s t thinning i s done .
To t al numb er harve s t ed i s , obviously , greater with thinning than without ;
smaller the minimum merchan t ab l e d . b . h . , the greater the po tent ial numb er .
the
The
maximum numb er after precommercial thinning is about the same as the numb er that
would no rmally a t t ain the d e s ired minimum merchantab le d . b . h .
left unthinned .
Many trees are cut at the f i r s t commercial thinning ,
each suc c e s s ive thinning .
stand wer e
and progr e s s ively fewe'L at< -,
The numb er carried to f inal harves t dep ends on tree
s iz e and des ired s t o cking l evel a t that t ime .
s i t e qual ity ,
if the
and treatment regime .
�/ Or other p redetermined obj e c t ive .
S i z e d epends on r o t a t ion age ,
The numb er remaining for f inal harve s t is
nearly always fewer i.n a stand tha.t h a$ been.' thinned than i.n one ca.rr;ted t o final
harves t without thiimi:n g .
S i z e of Harve sted Trees
The effect o f thinning on tree s iz e must b e examined
s iz e s are compared at f inal harvest ,
(lfcj)
in proper p erspective .
o f all trees in two s tands having d ifferent numb ers o f t r e e s .
should compare Dq of an equal nwriber of larges t trees :i..n the two
Instead > we
Wher e a s
stands .
Dq o f a l l t r e e s at final harve st may b e much! great er in a thinned s tand
a comp ar ab l e unthinned s tand ,
When
it is misl eading to c ompare average d . b . h .
than in
the Dq of an e qual numb er o f largest: trees will
o f t en be s imila� in the two s tand s .
In s tands receiving only corrrmercial thinning , Dq at f inal
within
harvest will usually b e
5 percen t o f D q o f the same number of larges t tree s in a comparable unthin­
ned s t and .
Increased growth rates of res idual trees is o f f s e t by removal i.n
thinnings of s ome larger than average trees that would o therwi s e h e present at
final harve s t .
In s t ands that have b e en precommeroia ll� thinned ) the maximum
gain in Dq of a given numb er of largest t rees at final harve s t will mo s t l ikely
be about
20
percent .
The gain will commonly be l e s s
than th i s .
Ga in might b e
a l i t t l e greater i f t h e precommercially t hinned s t and i s carried t o final harve s t
with no commercial thinning ; the longer the t imespan , the great er the gain .
Usabl e Volume
The maj o r gain in usable volume from · commercial thinning come s from prev�nting .
loss of merchan t ab l e mor tality .
P o t ent ial gains are greate s t on bes t sites
b ecause s t ands develop more rapidly than on poor s i t e s ; the mor e rapidly the
s t and d evelo p s ,
the great er the rate of merchantab l e mortality .
Addi tional gains in usab l e volume from early control o f s pacing (precommer c ial
thinning)
come from concentrating all sub sequent growth onto t r e e s tha t will b e
merchantab l e .
Po t ent ial gain s are greater on p o o r s it e s than o n average s ites ;
the more slowly a s t and--with a given number of well -spac ed t r e e s --d evelops ,
longer the t ime i t has l e s s than full s to cking ;
the longer this t ime )
the
the greater
the relative increase in u s ab l e yield b e c ause trees ar e subj e c t ed t o less com�
p e t i t ion .
Maximum ab solute gain i s ,
s i t e s than this ,
apparently � on s it e IV land .
growth r a t e s are so slow that ,
ab solute gain is l e s s than on s i t e IV land .
On p o o r er
even with a large relative gain ,
Poten t ial gains from a precommercial t hinning will no t: be full y real i z ed unle s s
it i s followed by another entry a t t h e proper t ime .
b e a commerc ial thinning .
This next entry will usually
In some ins t ance s , however �
th e precommerc ially
thinned s t and may be carried t o f inal harve s t with no fur ther
thinned t o a spac ing commensurat e with this obj e c t ive .
thinning if j_t i s
Dis tribution o f Y ield Over T ime
The proport ion of t o t al usabl e produc t ion rema ining for f inal harves t
vari es >;qi-th
cubic volume produced ;
The pro­
thinning regime but will l ikely be c l o s e to
the o ther
30
70
percen t of the t o tal merchantab l e
percent i s removed in thinnings .
port ion of boa.rd-foo t produc t ion left for final harves t will b e a l it tl e greater .
In s t and s receiving commercial thinning only , this f inal harves t volume will
l ikely be no mor e than about 85 percent of the volume that wou l d have been har­
ve s t ed from the s t and if i t had not been thinned ,
·
' ·
E f f e c t o f Rotat ion Ag e
Ages at t..:rh ich gains are ass e s sed have a · sub s t ant ial eff e c t on how much is gain ed .
Obviously ,
the longer the rotation--on a given sit e��the greater the potent ial
gain ( i . e . � prevention of l o s s )
mortality to b e harvested ,
on the o ther hand ,
p o int ,
from commercial thinning ;
there is more po t en t ial
A large part o f the gain from preeommercial thinning ,
comes before the· first commerc ial thinning .
the gain in m . a . i .
d ivided by t ot al age)
(mean annual incremen t )
(i . e . �
from precommercial thinning d ecreas e s with increas ing age "
In this regard , we should consider the age at wh ich m . a . i .
this i s affected b y utili:;:; a't ion s t andards and treatment .
volume m . a . i .
s it e s .
Beyond a c er t a in
to tal product ion
culminates and how
Cu lminat ion of total�
in normal s t and s apparently occur s at about the s ame age on all
Culminat ion of merchantable volume , however ,
occur s progr e s s ively later "
depending on how much of the total volume is deemed merchantab l e ;
merchantabil ity rat io ,
the later the culminat ion .
culminat e s much later than t o t al cub ic volume m . a . i .
s t andard ,
o th�:t' _ than , t:_Q!:al ' volume ,
p o orer s i t e s .
·
!m . a . i .
Culminat ion o f m . a . i .
\
in a corresponding unthinned s t and .
the lower the
Thus , board-foot volume m . a . i .
Fqr any merchantab il ity
culminate s later on progr es s ively
in a thinned s t and occur s earlier than that
Effect o f Merchantab ility S t andard
Relat ive gain from commercial thinning alone decreases as l e s s of the total
volume i s deemed usab l e ;
relat ive gain from preeommercial thinning increases
as l e s s o f the volume i s deemed merchantabl e .
Thus ,
gain from commerciaL. thin�
ning alone is greatest in terms ·of t o tal cub ic volume ; gain from precomm r c ial
�
thinning is great e s t in t erms of b o ard-foot volume .
The effect of minimum merchantable d . b . h . on t o tal merchantable pro duc t io n is
greater for s t ands receiving only commercial thinning than for s t and s that were
precommerc ially thinned b e cause precommerc ially thinned s t ands were thinned to
a spacing
commensurate with this .minimum d . b . h . ; furthermore , wider spacing
results in greater product ion of board-foo t volume .
larger the minimum merchantab l e d . b . h . ,
In natural s t ands , the
the greater the amount of comp e t i t ion
t o wh ich crop trees are sub j e c t ed p r io r to the first 'po s s ible commer c ial thin­
ning ; more of the p o t en t ial growth goes onto non-crop trees ins t ead of crop
trees .
S ome e s t imat e s of usab l e product ion and gains from thinning are summa rized in
t ab l e s
1 and 2 and figure 1 .
minimum merchantab l e d . b . h . ,
The s e e s t imat e s apply t o sp e c ific ro t a t ion ages ,
and thinning regimes .
Table
1 provides e s t imat e s
o f t o tal yiel d , by various measur e s ; mult iply mean annual increment by ro t a t ion
ages to get t o t al yield .
Figure
absolute and relat ive terms .
1 and t ab l e 2 focus on gains in yield , in b o th
I
MEAN ANNUAL INCREMENT AT SPECIFIED ROTATION AGES , BY SITE ,
TABLE 1 .
'·
AND
TREATMENT ,
VARIOUS MEASURES OF PRODUCTION; TREES 6 . 0
I
INCHES AND LARGER IN DIAMETER AT BREAST HEIGHT
*
Measure of production
S i t e , age , and treatment
G
Square
feet
S i t e I,
8 5 years :
Unthinned
Unthinned plus salvable
**
Commercial thinning alone
Precommercial thinning
commercial thinning
Site I I ,
+
90 years :
Unthinnned
--Cubic feet-215 . 8
212 . 2
227 . 8
224
280 . 7
194 7 . 7
1 7 28 . 6
1 70 . 4
167 . 3
1175 . 9
1045 . 8
214 . 2
207 . 1
1 37 6 , /;
1 18 2 . 4
1490 . t.
1300 . 2
2 70 . 1
5 . 03
228 . 9
221 . 5
**
2 . 79
129 . 0
125 . 7
Commercial thinning alone
3 . 75
1 55 . 8
4 . 21
176.5
**
2 . 36
91 . 6
Commercial thinning alone
95 year s :
Unthinned
Unthinned plus salvab l e
Precommercial thinning +
commercial thinning
Site IV,
100 year s :
Unthinned
Unthinned plus salvable
Precommercial thinning +
commercial thinning
S it e V , 105 year s :
Unthinned
Unthinned plus salvable
**
Precommercial thinning +
commerci�l
thinning
Metric conversion :
2 . 94
135 . 2
169 . 9
109 5 . 3
931 . 8
87 . 9
5 28 . 2
939 . 3
3 . 41
128 . 7
122 . 7
1 . 88
57.7
53 . 6
55.3
281; . 1
2 . 52
82 . 4
77.2
98 . 1
778 . 4
427.4
54 7 . 4
4 40 . 4
744 . 6
607 . 9
27 6 . 8
189 . 4
4 26 . 9
3 20 . 6
565 . 8
� ---
\
I
I I
I.
I
I
I
I
- ' - '�i
192 . 9
X
0 . 2296
G j.n square
CV in cubic feet per acre
X
0 . 0700
CV in cubic
_
CVTS = cubic volume o f total stem;
to a 6-inch (15-cm)
top (Scribner volume is
to a 5 -inch (13-cm)
i
I!
\l
4 36 . 9
G in square feet per acre
top d , i .b . ;
CV4 = cubic volume
IV5 = Internat ional board-foot v�J.ume
top , 1 / 4 -inch kerf; SV6 = Scribner board-foot volume
the formula version applied
CV4 , IV5 , and SV6 exclude volume
For this comparison,
of f inal harves t
741. 7
lll 9 . 5
59.6
714 . 5
867 . 2
103 . 8
1 . 95
1091 . 6
832 . 0
131 . 6
2 . 87
meters per hectar e .
to 16-foot logs) ,
1231 . 7
91 . 6
t o a 4-inch (10-cm)
**
175 . 9
95 . 6
2 .47
meters per hectare .
G = basal area;
1636 . 5
1466 . 1
2 89 . 3
4 . 64
Site I I I ,
1863 . 5
5 . 92
Commercial thinning alone
+
1397 . 6
1627 . 1
179 . 2
commercial thinning
1546 . 1
.o
3 . 40
Precommercial thinning
--Board feet--
2 7 8 . ll
3 . 22
\
SV6
5 . 55
**
Unthinned plus salvable
*
3 , 65
3 . 87
\
is
in
the stump .
all merchantable mortality o ccurring within 10 years
assumed to be salvable a t final harves t .
l
\I
TABLE 2 .
Site,
GAINS IN }ffiAN ANNUAL INCRE}mNT TO SPECIFIED ROTATION AGES,
BY SITE AND VARIOUS }ffiASURES OF PRODUCTION ; TREES 6 . 0
*
INCHES AND LARGER IN DIA}ffiTER AT B REAST HEIGHT
Measure of production
age , and treatment
**
G
SV6
ABSOLUTE GAIN
Square
feet
Site I,
85 years :
Commercial thinning alone
Precommercial thinning +
commercial thinning
***
·'
Difference
S i t e I I , 90 year s :
Commercial thinning alone
Precommercial thinning +
commercial thinning
***
Difference
Commercial thinning alone
commercial thinning
***
+
Site IV, 100 years :
Commercial thinning alone
Precommercial thinning +
commercial thinning
***
61 . 5
46.1
236
170
56 . 7
321
262
145
91.
10 . 9
10 . 6
1 . 24
35 . 0
31 . 2
1 . 63
49 . 7
.81
20 . 6
17 . 9
1 . 27
4 ;1. . 3
38 . 3
20 . 4
1.56
.40
8.2
6.5
18
. 94
33.1
31 . 1
24 . 6
179
1.71
. 57
22 . 8
21 . 9
143
128
. 54
Difference
50 . 6
--Board feet--
. 37
.46
Difference
S it e V,
2 . 05
. 39
S ite I I I , 9 5 years :
Precommercial thinning
1 . 68
--Cubic fee t--
85
259
14 . 7
20 . 7
24 . 9'
92
209
114
118
72
37
228
190
1. 9 7
153
-3
168
105 years :
Commercial thinning alone
Precommercial thinning +
commercial thinning
***
.57
Difference
22 . 8
21 . 9
143
128
PERCENTAGE GAIN
Site I ,
Percent
85 years :
Commercial thinning alone
Precommercial thinning
commercial thinning
***
'+
90 year s :
Commercial thinning alone
Precommercial thinning
commercial thinning
***
+
Site I I I , 95 year s :
Commercial thinning alone
commercial thinning
***
+
Difference
S it e IV, 1.00 year s :
Commercial thinning alone
.P recommercial thinning +
commercial thinning
***
Difference
S it e V ,
21
1.5
12
53
27
25
20
18
8
5
4
5
36
20
18
12
48
27
26
21
11
Difference
Precommercial thinning
22
10
Difference
Site I I ,
43
7
28
15
43
31
16
16
38
22
7
14
29
6
19
8
10
8
5
15
14
17
26
26
9
7
3
-1
35
34
36
38
40
50
66
26
27
32
21
39
105 years :
Commercial thinning alone
Precommercial thinning
commercial thinning
***
Difference
29
29
38
38
. 40
·*
Gains are relative t o unthinned plus salvable .
**
G = basal area ; CVTS = cubic volume o f total s tem ;
to a 4-inch
(10-cm)
a 5-inch ( 13-cm)
a 6-inch (15-cm)
top d . i . b . ;
50
66
CV4 = cubi c volume
IV = International board-foot volume t o
top , 1 / 4 -inch ker f ;
SV6 = Scribner board-foot volume t o
t o p (Scribner volume is t h e formula version applted t o
CV4 , IV5 , and SV6 exclude volume in the s tump .
16-foot logs) .
***
Dtfference between precommercial thinning + commerd.al thinning and
commercial thinning alone ts gain due to precommerciaJ. thinning .
(
l
I
I
BO
l
so
40
<
�
�
z
1 :({
! <!I
30
20
10
..
'
0
i/
- 10
- 20
80
so
1 00
1 20
1 80
1. 8 0
2 0 0�
1 00
1 80
1 40
1 20
INITJ�L SITE INDEX (100-y�a r-basis)
1 80
200
1 40
B
40
z
:;:;::
30
(!J
w
(!J
�
z
20
iW
•U
J o::
. w
i O..
10
0
10
80
Figure 1 .
\
Gains in merchantable cubic volume ( CV4) due to thinning :
A , Ab solute gain s ; B , percentage gaj"ns ..
.1. '
I.
I lI
' I
I.n Summa�y
The greatest potential gain in usable product ion due to conunercial th :Lnning is :.
- on the best s ites .
- with long rotation .
- with close utilizat ion standards .
The greatest potent ial addit ional gain in usable production due to early precom­
merc ial thinning ( control of spacing) is :
- on poorer than average sites .
- with shorter rotations . I
- with poorer utilization standards .
LITERATURE CITED
Bruc e , D . , D . J . DeMars , and D . L . Reukema . 1 9 7 7 . Douglas-fir managed yield
simulator--DFIT user ' s guide . USDA For . Serv . Gen . Tech . ·Rep . PNW-5 7 . Pac .
Northwest For . and Range Exp . Stn . , Portland � Oreg . 2 6 p .
Reukema ) D . L . , and D . Bruce . 1 97 7 . Effects of thinning on yield o f Douglas-fir �
Concep t s and some estimates obtained by s imulat ion . USDA For . S erv . Gen . Tech .
Rep . PNW-5 8 . Pac . Northwest For . and Range Exp . Stn . , Portland , Oreg . 3 6 p .