PLACE OF PARTIAL CUTTING IN OLD-GROWTH

PLACE OF PARTIAL CUTTING IN OLD-GROWTH STANDS
OF THE DOUGLAS -FIR REGION
Leo A . Isaac,
Silvicultur is t
U. S. Department of Agriculture
Forest Service
Pacific Northwest Forest and Range Experiment Station
Portland, Oregon
March 1956
Page
.
1
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Regional average of results of partial cutting .
. .
Growth and mortality. f i r s t five years after logging .
Growth and mortality. second five years after
logging . . . . . . . . . . . . . . . . . . . . . . . .
Growth and mortality for entire ten-year period
after logging . .
.. . . . . . . . . . . . . . . . . .
Growth of r e s e r v e t r e e s before and after partial
cutting . . . . . . . . . . . . . . . . . . . . . . . .
Logging injury to the r e s e r v e stand . . . . . . . . .
Purposeandscopeofthestudy
Causes of loss and comparison with loss in undisturb-
.
West Central Oregon Cascade forests . . . . . . . .
A two-age-class stand . . . . . . . . . . . . . . .
Decadent old growth with a light understory . . . .
Pureold.growthDouglas=-fir . . . . . . . . . .
Thrifty middle-aged stand of pure Douglas-fir . .
Results of partial cutting under specific stand conditions
Summary of West Central Oregon Cascade forests
...........
Ahigh.drysite . . . . . . . . . . . . . . . . . . .
Northern Oregon Cascade forests
A watershed cutting in overmature Douglas-fir
.............
Northern Washington forests
Old-growth Douglas - f i r with heavy mixture of
cedar
Old-growth Douglas -fir blowdown
A two-story North Olympic blowdown
Summary of northern Washington forests
.
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O
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O
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O
O
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..
.
O
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O
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Page
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29
Douglas - f i r stand more than 500 years old in
transition stage
Temporary plot record of similar ad joining
stand..
Effect of second cut on a similar adjoining stand
Effect of third cut on a similar adjoining stand
Summary of South Olympic a r e a s
..................
.....................
.
..
.........
Old-growth fog belt forests . . . . . . . . . . . . . .
The spruce-hemlock stand. . . . . . . . . . . . .
Scattered old Douglas-fir and cedar with
hemlockunderstary . . . . . . . . . . . . . . . .
Scattered old Douglas -fir and spruce with
hemlockunderstory . . . . . . . . . . . . . . . .
S u m m a r y of old-growth fog belt forests . . . . . .
Young-growth fog belt forest with scattered old
trees.
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O
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O
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O
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O
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Old-growth Douglas -fir with P o r t -Orford-cedar
mixture
........................
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Summary and discuasian . . . . . . . . . . . . . . . . . .
Partial cutting in fringe types on severe sites
Selected literature cited.
.................
PLACE O F PARTIAL CUTTING IN OLD-GROWTH STANDS
O F THE DOUGLAS -FIR REGION
Leo A . Isaac
INTRODUC TION
During the e a r l y 193Qts, a s u s e of the logging truck and tractor
increased, a form of partial harvesting mature and overmature v i r The cutting
gin stands developed in the Douglas-fir region (2).
pattern varied from taking a few scattered high-grade t r e e s per a c r e
to c l e a r cutting small a r e a s . P a r t i a l harvesting caught on quickly
because at that time only the high-grade t r e e s could be logged a t a
reasonable margin of profit, This was a new procedure in the
Douglas - f i r type, and its effect on the future stand was unknown (7).
-
Thinning and stand-improvement cuttings had long been accepted
practices in young and thrifty stands of many f o r e s t types with intol*
e r a n t species, including Douglas -fir (3).
But in the 1930fs, the
single-tree system of cutting was advocated for virgin f o r e s t s of
mature or even decadent old-growth Douglas-fir virgin f o r e s t s with
hemlock, true f i r s , and cedar in mixture and in understory. Sometimes these mixture species predominated. The system cannot be
called a thinnihg in these overmature stands since thinning commonly applies to young, o r a t l e a s t thrifty stands. Neither can i t
be called selection cutting, since t r u e selection cutting consists of
harvesting the r i p e t r e e s from an all-aged f o r e s t of tolerant species
withreproductioncontinuo~slyreplacingthe t r e e s c u t ( 1 ) . Since i t
is neither a true thinning nor an individual t r e e selection cutting,
the partial removal of t r e e s from the stand, when mentioned in this
report, will be called partial cutting (4),
-
Original proponents of the system called i t selective timber
management in the Douglas-fir region (5). It embodied successive
light cuts taking out the better t r e e s mostly over 40 inches d. b. h.
It a l s o assumed that s m a l l e r t r e e s would continue to move up into
the l a r g e r diameter c l a s s e s , and that gradually an all-aged f o r e s t
would develop. The system, a s originally described, made occasional reference to c l e a r cutting in s m a l l groups o r spots if s a t i s factory r e s tacking did not occur after s e v e r a l light tree-selection
cuts. But the f i r s t stages of the cutting system did not turn out a s
anticipated, and time had not permitted the l a t e r phases of the s y s tem to get beyond the "theory" stage before logging methods changed.
This system was thought justified, f i r s t , by the high cost of
constructing a road system into the a r e a s , and second, by prospects
for a rising m a r k e t for the low-value elements of the stands, AS
m a r k e t s and transportation improved, m o r e emphasis was given to
removal of high-risk, inferior, and dead t r e e s as well a s the good
t r e e s in the stand; but the cut still included only merchantable t r e e s
from the Largest and oldest c l a s s , mostly Douglas-fir.
Slash burning following partial cuts proved impractical, and i t
soon became evident that cutting m o r e than a third of the stand would
leave an intolerable s l a s h hazard and would magnify windfall r i s k .
As partial cutting got under way i n the region, the upper l i m i t of cut
became r a t h e r automatically s e t a t about one-third of the g r o s s
volume--a few cuts were heavier, and many were lighter (4).
.
1
9
PURPOSE AND SGQPE O F THE STUDY
Although based largely on theory, the partial-cutting system
quickly gained momentum and posed problems for which answers
were not available. F o r one thing, a tree-selection system p r e supposes an all-aged forest, but i t was not known if partial cutting
would bring about a n all-aged f o r e s t with Douglas - f i r in the stand.
P e r h a p s partial cutting would speed up natural transition to a climax
f o r e s t of m o r e tolerant but l e s s valuable species and eliminate the
Douglas-fir. This transition takes place a s natural stands grow old
in the absence of complete destruction of stands by fire, insects, o r
d i s e a s e (4, 6).
.
.
p
1
1
9
Then too, i t was not known i%overcrswded and overmature
stands could be rejuvenated by partial cutting and growth of the
r e s e r v e stand increased. And what effect would this type of cutting
have on the kind and quality of m a t e r i a l produced? Some claimed
that partial cutting would prolong the life of the remaining stands of
old-growth Douglas -fir, extending the cutting period of high-grade
c l e a r m a t e r i a l and plywood logs. Others claimed it would m o r e
quickly skim the c r e a m af this m a t e r i a l from the oldogrowth
stands
.
Much other information was needed, FOP example, could partial cutting be done on steep, rough topography? Also, how much
logging damage would be done to reserve trees, and how wouId i t
affect t r e e vigor and decay entrance ? Because conditions within
thip fares t type are extremely variable, recommendations were
needed to indicate the conditions under which partial cutting was or
was not likely to succeed. Only field tests and demonstrations could
supply all the wanted facts.
Accordingly, a study was started in 1935 to record the effect of
such partial cutting a s was being done on national-forest timber sales.
Starting in advance of cutting, the study was designed to record, by
species: The original stand, cut, logging breakage or injury, subsequent windfall, other mortality, and growth of the reserve stand;
also change in stand composition, including incoming regeneration.
The s ystern was recommended and applied to spruce-hemlock
and upper slope mixtures as well a s to pure Douglas-fir stands.
Therefore, study a r e a s were s e t up in the subtypes a s well as in the
major type of the region.
Sample plats were established from year to year a s cutting a r e a s
became available, until 17 a r e a s had been sampled totaling 76 a c r e s
of tagged, measured, and remeasured trees. Fifteen of the a r e a s
w e r e in typical old-growth stands distributed from Darrington,
Washington, on the north to Oakridge, Oregon in the south. An additional. graup was located in Port-Orford-cedar, and one, the
seventeenth, in a two-aged spruce-hemlock stand in the fog belt
from which many large, scattered, old-growth trees had previously
been cut.
Because it was impracticable to distribute a large number of
small plots over a large timber-sale a r e a on the national forests
without interfering with the operation, no effort was made to get a
true random sample of entire cutting areas. Instead, a representatiare p a r t of an area was selected, and a solid block of sample plots
with all trees tagged was put in. This concentration of plots minimized interference with logging operations. Existing timber-sale
contracts made no provisions for leaving portions of a r e a s undisturbed; therefore, check a r e a s could not be s e t up for statistical
comparison of growth and mortality in uncut and p a r t i d l y cut areas.
Because of the design of the study, a statistical analysis was not
m a d e for this report, Enstead, the a r e a s were treated as case
studies, the pesults averaged, and general conclusions drawn from
these averages.
The stands varied in stand composition and condition and in age
f r o m 150 to 600 y e a r s . Size of sample in a locality varied from
t h r e e to fifteen 1 - a c r e plots; these were in one o r m o r e separate
3- to 6-acre blocks, If there was a marked difference in age o r
stand s t r u c t u r e on p a r t s of a l a r g e a r e a in a locality, s e p a r a t e blocks
of sample plots were put in. Douglas-fir was p r e s e n t on a l l but one
a r e a , which had a Sitka spruce stand. The Douglas - f i r was even
aged and usually in the oldest age c l a s s present. Some of the m o r e
tolerant associates were equally old, but m o s t were younger and
made up a well-developed understory. This understory was important in m o s t of the r e s e r v e stands a s it usually was not taken in the
early cuts.
All of the study a r e a s have had a 5-year remeasurement for
growth and m o r e frequent mortality checks. Ten of the a r e a s have
had the 10-year remeasurement. In addition, t h e r e is a record of
a "second cutf1and a "third cutH on one a r e a , and on another the
permanent plots were supplemented by temporary plots to give m o r e
complete coverage.
REGIONAL AVERAGE O F RESULTS O F PARTIAL CUTTING
Although the stands varied in age, density, composition, and
condition, 15 of the 17 study a r e a s w e r e sampled in a s i m i l a r mann e r and were sufficiently s i m i l a r otherwise to permit averaging for
volume cut o r destroyed, mortality from windfall or other causes,
logging injury, and growth.
1/
of stands varied from 93,000 to
The g r o s s volume
177,000 board feet per a c r e , averaging 137,000 (tables 1 and 2).
The cut varied from 17,000 to 86,000 board feet per a c r e , and
averaged 50,000 o r 36 percent of the stand.
1/ The term "gross volumeFta s used in this r e p o r t means the
total\olume of all living t r e e s with no deduction for decay o r other
defect, Some decay was p r e s e n t in a l l stands and sometimes
approached one-half of the stand volume, but there was no way to
evaluate i t accurately in this study. All volumes a r e given in
board feet Scribner r u l e ,
Table 1.--0rininal
stand and out kith annual m r k l i t y , gross ~rowth. and net inoremnt durily: f i r s t five years in old-xrmrth Dou~las-fir stands.
(Per-acre values are ~ i v e nin number of trees and Soribnsr volw--15 areas cornrising 64 aores4
Original stand
Sample plot designation
No. of
trees
-
h r aore
W i l l a x a t t a National Forast
P.S.P. NO. 6
7
;
I
w
I
Y t . h o d Natioaal Fomrt
P.S.P. E ~ O , 6
7
8
9
Gross
voluma
-
Bd. f t .
per aore
I
Cut or destroyed
No. of
trees
Per aore
Gross
volusle
-
Bd. f t .
per acre
Annual mortality and grosr growth
Annual aat
Mortality
inorenrent
Gross growth
Vfindf a l l
Other
Gross
No. of
Gross
Gross
No. of
Wo. of
Gross
No. of
trees
r o l u ~ ~ trees
volums
trees
oolur~e
tmes
roluere
-
Psr aare
Bd. ft.
per aore
Per aore
98,032
158,966
121,795
47,321
25.6
15.1
9.2
33.7
40,256
54,309
om&
.06
0%
53.595
.06
.2O
205
837
382
37
89.3
92.733
26.7
16.3
12.3
6.0
3 l U
17,128
40.832
20,763
.32
.20
254
3%
10ea018
&
82.6
57.6
64.5
3
52.4
16.2
9.3
39W
----
11
.58
.30
357
----
@
.66
.06
5%
16
W
--
Yt. Baker Iatlolul Pornst
P.8.P. Ha. 2
137.3
We126
39.7
43,279
.B
3Wr
.%
Olympia lational Forest
P.s.P. Mo. 17
18
19
84.9
58.0
53.2
157,301
102,588
127m
170,404
176.M
162,786
18.5
10.4
42.932
61,713
21,721
2.50
.80
-52
6,916
337
.&
659
.60
20
21
22, 23, a d
dr
Bd. Ft.
per acre
g$
47.7
$2
12.0
2%
72,803
*Ira
.56
.06
3,010
3.154
232
--
.&
2.08
.&I
---
371
Per acre
Bd. f t .
p r acm:
Fbr acre
0.24
207
-0.38
.38
-.80
:z--
34%
---
g
.10
93b
--
---
317
837
61r8
052
659
--
1,172
501
517
435
-
Bd. f t .
per aam
Par aore
Bd. Pt.
per aore
516
3 5
33.0
57,730
lOln358
80.47
209
d.8-3
SllrsT72
dco
63
301
59.0
62.0
45.0
n.0
&,0g2
77,085
121,616
90,218
194
93.6
66,816
83 031
40:630
104,827
-- 6609
- &
- -26
-- 6.726 -
- .&
.10
-
--
.60
-2.50
-72
.72
-80
-2.44
-6,-
Reserve stnnd
5 years
after outting
Xo. of
Gross
trees
mime
ls9
53.9
44.0
170
-3,ml
16.2
22.6
781
32.0
--
- .7k -~r,sn
-
&.a
96,060
66,715
86,080
a b l e 2.--~&erve stand 5 and 10 years afWr eutti*
annual mortality, pross ~rowth,and net increment. durinp second five
years in old-growth Douglas-fir stands. (Per-acre values are niven in number of trees and
Scribner voldine--10 areas comprising 47 acres.)
I
Salnple plot designation
Reserve stand
5 years
after cutting
volurns
-
Second five years
Annual mortality and gross ~ r a n t h
Mortcility
Growth:
Windfall
Other
gross
trees
volume
trees
volume
volume
---Per acre
--
Bd. f t .
per acre
Per acre
57,176
102,123
92,l.b
0.44
9
52.7
36.3
62.0
.oB
13
•
M t . Baker National Forest
P.S.P. NO. 2
93.6
66,816
-70
80
1.30
53.9
k.0
44.2
22.6
24.8
33-5
83.031
40,630
ldcr827
96,060
66,715
82,521
661
&-0
79,503
Willamette National Forest
P.S.P. MO. 6
7
I
Bd. f t .
per acre
.46
132
0.14
1,619
.06
m
I
Olympia National Forest
P.S.P. NO. 17
18
'19
20
21
22,
23, and &
Weighted average
1/
24
2.90
020
Per acre
2,615
3 a
1,033
230
Bd. f t .
per acre
trees
Bd. f t ,
per acre
Per acre
Bd. f t .
per acre
5b.2
37.0
61.6
57,494
93,W
93,777
85-8
68,943
52.2
26.9
21.2
23.2
35.1
83,151
26,830
106,180
83,908
62,820
81,253
42.1
76,2Lr2
Per acre
267
0.30
64
.4
415
78
419
- .08
-1,805
3a
M6
971
-1 .&
425
e l 4
102
-62
565
787
420
-3.02
u+
*&
-08
r76
.&
A6
627
A0
boS
0%
-60
After the f i r s t 5 years there was some adjustment i n plot boundaries end numbered trees.
seoond 5-year reoord do not always check with the l a s t 2 columns.
229
9eS
341
356
724
583
- *34
-028
-032
-32
-.38
Reserve stand
10 years
aftur cutting
vulume
Bd. f t .
per acre
71
1,738
409
905
702
.d,
Annual
net ino remnt
-
24
-2,760
271
-2,430
779
--
2%
-652
46.2
For that reason, the f i r s t 2 columns in the
Growth and Mortality, F i r s t Five Years After Logging
Some a c r e plots of each study a r e a and 5 entire a r e a s of the 15 showed
a net growth per a c r e for the 5-year period. Volume l o s s varied
greatly between a r e a s . Annual growth of t r e e s alive a t the end of the
f i r s t 5 y e a r s after cutting averaged 535 board feet p e r a c r e (table 1).
But mortality from windfall and other causes on 10 a r e a s was SO
g r e a t that total l o s s m o r e than offset growth. The average total
mortality for all a r e a s was 1,689 board feet per a c r e p e r year.
Hence, the 15 study a r e a s had a net l o s s of 1,154 board feet per
a c r e per year for the f i r s t 5-year period after cutting. Heavy loss e s on three a r e a s raised the average severalfold.
Growth and Mortality, Second Five Years After Logging
Some a r e a s stabilized within the f i r s t 5 years following logging,
but others did not (table 1). Records a r e available for the second
5-year period on 10 of the 15 a r e a s (table 2). Two of these 10 a r e a s
showed a net gain for both the f i r s t and second 5-year periods, and
an additional 3 a r e a s (making a total of 5) apparently stabilized and
showed a net growth during the second 5-year period. The remaining 5 a r e a s continued to show a net l o s s . The only evidence that
l o s s e s would eventually subside was the fact that m o r e a r e a s showed
a net gain during the second period than during the f i r s t period.
Annual growth of t r e e s alive a t the end of the second 5 years a f t e r
cutting averaged 583 board feet per a c r e . On 10 a r e a s , the second
5-year record showed an average annual l o s s of 652 board feet per
acre.
Growth and Mortality for Entire T en-Y e a r Period After Logging
The annual net l o s s for the f i r s t 5 years was 1, 154 board feet
and f o r the second 5 years was 652 board feet, making a weighted
average of 941 board feet p e r a c r e p e r year for the f i r s t 10 years
a f t e r logging. The weighted average current growth r a t e of t r e e s
that remained alive for the same period was 555 board feet p e r
a c r e p e r year. 4/ If all mortality ceased (and there is no reason
to believe that i t will), it would still take m o r e than 1 6 y e a r s a t the
2 / Since records for the s a m e number of: a r e a s were not
a v a i z b l e for the f i r s t and second 5==yearperiods, weighted averages
were used for 15 a r e a s in the f i r s t 5 years and 10 a r e a s in the
second 5 y e a r s .
current rate of gross increment to regain what was lost in the preceding 10 years. h other words, 26 years after cutting, the average
of all stands would contain about the same volume of timber as they
had when the first cutting operation was completed. The process is
apparently something like this: After cutting, a few stands put on net
volume growth from the beginning, some make no net growth, s o m e
gradually lose volume, and others go to pieces entirely; the average
after 10 years is still a net loss.
Growth of Reserve Trees Before and After Partial Cutting
All a r e a s showed gross growth after logging, but were individual
t r e e s actually released by cutting, and was growth accelerated in the
reserve stand? To answer these questions, 769 trees were increment bored on the areas listed in tables 1 and 2. Growth measurements were made for the 10 years before cutting and the 10 years
after (table 3). Trees were selected at random in all size classes
and from all species present.
AS the age and size of the individual tree increased, response
to cutting decreased. Douglas-fir usually belonged to the oldest age
class, and about two-thirds of these trees showed either a decline
in growth r a t e o r an unchanged r a t e after cutting. The same was
true for Sitlca, spruce where i t was present. The reverse was true
of hemlock, cedar, and silver f i r , which made up most of the trees
in younger age classes and smaller diameters in the understory;
about three-fifths of these trees showed accelerated growth. Of the
769 trees of all species, half showed increased growth, the other
half a decreased or unchanged growth rate. Sometimes severe logging injury was the apparent cause of lack of accelerated growth;
other times, i t was evident that the trees were not released by the
cutting. And sometimes the trees appeared too overmature and
decrepit to respond. It was not possible to correlate increased
growth on individual trees with average growth per a c r e after cutting, but it was apparent from core measurements that acceleration
in growth rate on half of the trees probably about compensated for
the decline in growth rate on the rest. Windfall and other losses
following cutting affected trees making accelerated growth and
others alike,
Table 3. --Effect of partial cutting on diameter growth-1 /
of individual trees
Species
II
I
I1
Total trees Increased
increment I diameter
bored
[
growth
No
change
II
Decreased
diameter
growth
Douglas -fir
229
72
47
110
Western hemlock
3 54
214
31
109
Western redeedar
81
46
10
25
Silver fir
31
21
2
8
Sitka spruce
74
29
0
45
Total number
769
382
90
297
Percent of total
100
50
12
38
1 / Based on radial growth 10 years before and 10 years after
cutting. determined by increment boring.
Logging Injury to the Reserve Stand
Logging injury to the r e s e r v e stand i s important not only because
of the physical damage to the t r e e s , but because the s c a r s a r e p o r t s
of entry for wood-decaying fungi. The nonresinous species, such as
hemlock, t r u e firs, and to some extent Sitka spruce, a r e v e r y s u s ceptible to decay. Since they occur in the understory and in mixture
with Douglas-fir in the region, logging injury to them i s of m o r e
than usual significance (figures 1, 2, 3, and 4). A s e p a r a t e study
of decay entrance in these species shows that 3 to 15 y e a r s after
injury m o r e than 63 percent of the logging s c a r s had decay in them
-
( 9 )*
Injuries in this study consisted of broken tops and damage to
the trunk, base, o r roots of the t r e e . Many t r e e s had m o r e than
one type of injury. The injury to the r e s e r v e stands in the 15 a r e a s
that a r e shown in table 1 varied from 17 to 50 percent, and averaged
3 4 percent of the t r e e s . Sometimes the injuries w e r e slight, but
other times they were g r e a t enough to r e t a r d growth o r kill the t r e e .
While the significance of a c c e l e r a t e d decay following logging injury
was recognized, volume of decay was not calculated and m u s t be
considered a s an undetermined amount over and above other l o s s e s
shown in this report.
Causes of L o s s and Comparison with L o s s in Undisturbed Stands
L o s s e s w e r e not confined to any single species, crown c l a s s , o r
locality. Because of variation in stand and exposure on the different
a r e a s , no d i r e c t relationship was found between percent of cut and
windfall 10s s e s .
Windfall was the g r e a t e s t single cause of l o s s (tables 1 and 2).
It happened a t a time when s i m i l a r l o s s e s were not occurring in
nearby virgin stands, although some windfall in virgin stands had
occurred e a r l i e r . In the f i r s t 5 y e a r s after logging, windfall l o s s e s
on the plots were practically double the mortality from a l l other
causes combined, Some l o s s occurred on 13 of the 15 a r e a s f o r
which the f i r s t 5-year r e c o r d was available; the average annual
windfall 10s s for the period was 1 , 099 board feet p e r a c r e p e r y e a r .
Windfall l o s s e s declined in the second 5 y e a r s to 627 board feet
p e r a c r e p e r year and about equalled mortality from other causes
on 10 of the a r e a s where the second 5-year r e c o r d was available.
T h e r e was some l o s s on all 10 of these a r e a s , In general, the
F i g u r e 1. --Widely s c a t t e r z d old-growth Douglas -fir in a dense
understory stand of hemlock and s i l v e r f i r just under comm e r c i a l s i z e . L a r g e t r e e s cannot be removed without
s e r i o u s injury to r e s e r v e . They should not be cut until
understory t r e e s r e a c h c o m m e r c i a l s i z e and injured t r e e s
can be salvaged. (F.S. Photo 429812)
Figure 2 . --Understory trees in this stand were mostly of good form
and commercial s i z e . Injured trees were'cut and salvaged
when large, old Douglas-firs we.re cut. (F.S. Photo 429807)
F i g u r e 3. - - P a r t i a l cutting in this type of f o r e s t left i n the r e s e r v e stand
decrepit, poorly f o r m e d , u n d e r s t o r y hemlock and decadent
old-growth hemlock and Douglas -fir. (F S Photo 437585)
..
F i g u r e 4. --Removing l a r g e t r e e s from a dense understory o r younggrowth stand cuts deep skidroads, t e a r s the roots and injures
the b a s e of many r e s e r v e t r e e s . (F.S. Photo 429784)
l o s s e s w e r e g r e a t e s t in the stands which had the heaviest original
volume, but r e s u l t s a r e not entirely consistent (tables 1 and 2).
Although actual m e a s u r e m e n t s a r e not available, it i s known that
windfall l o s s e s have o c c u r r e d on these plots since the l o - y e a r
period, to the extent that s e v e r a l a r e a s have had t o be c l e a r cut f o r
salvage. The data r e v e a l no way to predict where windfall l o s s e s
will s t r i k e , o r how to avoid them except possibly by lighter cuts.
L o s s e s from c a u s e s other than windfall have remained s o m e what constant, about 600 board feet p e r a c r e p e r y e a r throughout the
10-year period, and about equal the growth (555 board feet) of t r e e s
left alive. Exact c a u s e s of these l o s s e s have been difficult to isolate
and identify. Even b a r k beetle attack, the m o s t common cause, i s
difficult to identify a s the p r i m a r y and only cause of mortality.
B a r k beetle attack usually o c c u r r e d from 1 to 2 y e a r s a f t e r cutting,
and was commonly m o s t s e v e r e when l a r g e chunks of unmerchantable
m a t e r i a l w e r e left strewn over the f o r e s t floor. One group of plots
n e a r Cushman Lake, Washington, showed a heavy l o s s from beetle
attack. Logging injury, sunscald, and exposure a r e other causes
that contributed to l o s s . Often no cause could be a s c r i b e d .
As previously stated, a d i r e c t comparison of l o s s e s with and
without p a r t i a l cutting was not obtained because i t was not feasible
to establish check plots to m e a s u r e normal l o s s e s in uncut virgin
s t a n d s . However, r e c o r d s of mortality in untouched, old-growth
stands a r e available from other s o u r c e s .
Sample plots in a declining 350-year-old Douglas-fir stand in
the Wind River Natural A r e a showed a periodic annual mortality of
759 board feet p e r a c r e and a net growth of 8 board f e e t p e r a c r e
p e r y e a r . This was f o r the 6-year period of 1947 to 1953, of which
1949 and 1951 w e r e s e v e r e windfall y e a r s (8).
-
During the 5-year period, 1948 to 1952, f o r e s t s u r v e y c r e w s in
s e v e r a l counties of w e s t e r n Washington and Oregon estimated m o r
tality occurring during 5 y e a r s previous to plot examinations.
G r o s s growth of merchantable t r e e s was determined by increment
borings on 169 1 / 5 - a c r e plots, and 5-year mortality was estimated
on 1, 042 plots (table 4). This table, which gives r e s u l t s by age
c l a s s e s starting with age 180, shows an a v e r a g e g r o s s growth of
500 board feet, a mortality of 345 board feet, and a net growth of
155 board feet (Scribner r u l e ) p e r a c r e p e r y e a r .
-
3 / E x t r a c t from f o r e s t s u r v e y file r e c o r d s . Robert B. Pope.
~ a ~ i 9 5 5 .
-15-
Table 4. --Growth and mortality in undisturbed old-growth
stands of the Douglas-fir region
Age
class,
years
180 - 250
260 - 350
360t
Uneven
I
Average
lvol./acre
bd, ft.
I
52, 106
65, 128
117,48 1
47, 325
I G r o s s growth I Mortality I Net growth
I bd. ft. / a c r e 1 bd. ft. / a c r e I bd. ft. / a c r e
I p e r year 1 p e r y e a r I p e r year
516
410
740
43 1
280
351
616
248
236
345
155
59
124
183
-
Average
75,212
500
F o r the purpose of comparison with study figures, these s u r v e y
f i g u r e s may be considered a s a conservative e s t i m a t e of mortality
and an optimistic e s t i m a t e of growth. This is t r u e because in the
original stand e s t i m a t e the f o r e s t survey made a deduction for decay
and considered only merchantable t r e e s , while the figures used in
this study made no deduction f o r decay and do include totally cull but
living t r e e s .
The foregoing r e c o r d s of mortality in undisturbed stands show a
net gain of 8 board feet p e r a c r e p e r y e a r for the natural a r e a , and
155 board feet n e t gain for the survey estimate, compared with a
weighted average annual volume l o s s in this study of 941 board feet
p e r a c r e for the 10-year period following p a r t i a l cutting. On the
basis of these comparisons t h e r e a p p e a r s to be evidence that partial cutting not only failed to r e s t o r e o v e r m a t u r e Douglas -fir stands
to a condition of thrift, but resulted in significant l o s s .
RESULTS O F PARTIAL CUTTING UNDER
SPECIFIC STAND CONDITIONS
The regional averages (tables 1, 2, and 3) show the effect of the
treatment on the type a s a whole, but these averages often obscure
many of the effects of partial cutting in certain stands. These m o r e
detailed effects become apparent from the history of plots in a specific f o r e s t type, a stand condition, o r a locality, and show in m o r e
detail the effect of partial cutting. Discussion of such r e c o r d s s u m marized by species for s i m i l a r types o r conditions follows:
West Central Oregon Cascade F o r e s t s
Four groups of sample plots located above Oakridge, Oregon,
a r e Willamette National F o r e s t permanent sample plots NOS. 6, 7,
8, and 9 , representing four distinct stand conditions occurring in
this general locality. Except for plot No. 9, they a r e typical of the
m o r e decadent stands on the d r y s i t e s in the southern Oregon
Cascades (table 5).
A Two-Age-Class Stand
P l o t No. 6 r e p r e s e n t s a Site IV stand of overmature old-growth
Douglas -fir that was heavily burned s o m e 85 y e a r s ago. The stand
was completely killed in some spots and partially killed in others.
Some of the l a r g e s t openings regenerated to young Douglas -fir in
the center and to hemlock and cedar around the edges. At the time
of partial cutting these young Douglas -firs w e r e below merchantable
size, and none were intentionally cut. T r e e s cut were all scattered
old growth. Where the old stand had not been completely destroyed
by f i r e 85 y e a r s ago, it was s o reduced in density that a heavy understory of hemlock and cedar had developed. Logging damage was
heavy in this residual stand when selected l a r g e old-growth t r e e s
were taken out. The s i t e was flat and d r y , and the hemlock that
had developed as an understory was of very poor quality, often
being of poor form and partially decadent before reaching m e r chantable size. The stand before cutting averaged 98,000 board
f e e t g r o s s volume per a c r e , mostly in the l a r g e old-growth
Douglas -firs. About 10 old-growth Douglas -fir t r e e s to the a c r e ,
with a total volume of 37, 000 board feet, w e r e cut in 1939.
Sixteen hemlock and cedar t r e e s in the 10-inch diameter c l a s s
with a volume of 3,000 board feet p e r a c r e were destroyed by the
logging operation; i n addition, about 40 unrecorded t r e e s under
Table 5.--Original
stand pi cut, with annual mortality. ~ r o s s~rowth, and net ilacrsraent during f i r s t and second 5 years in West Central Oregon
Cascade areas. (Per-acre values are niven by species in number of trees and Scribner volusle.)
Original stand
Plot location and species
-
millametto N. F.
No. 6
~ouglas-fi r
Western hemlock
Western redcedar
Total
Willanvette H. F.
NO. 7
Douglas-f i r
Western hemlook
Western redcedar
Total
-
-
-
Willemette 1. F.
NO. 8
Douglas-fir
Western hemlock
Total
W i l l ~ t t oN. F.
NO. 9
-
I
--
F i r s t 5 years
Annual m r t a l i t y and gross rrowth
Mortality
Gross growth
Windfall
Other
No. of
Gross
Gross
Io. of
Gross
~ r o s a No. of
trees
volume
trees
volume
trees
volume
volume
Cut or destroyed
I
Gmss
volume
No. of
trees
per acre
Bd. f t .
p r acre
Per rare
19.7
37.7
21.9
79.3
76.958
11.708
9.366
98 -032
9.7
6.7
9.2
P5.6
37,W
1,168
2.050
'22.0
26.7
3.7
5214
132,579
21,143
5.244
58.966
8.7
5.7
52,706
1,@6
117
54,309
3.0
lr6.2
605
121,795
Bd. f t .
Per acre
p r acre
7
15 .1
-9 .2
/
I
No. ef
trees
-39,498
Bd. St.
per acre
Per acre
--
---
0.6
A4
0,dr
0.04
11
11
.10
0.58
----
----
0.06
0.06
0.06
79
79
.06
0.52
--
266
8
0. %
I
I
274
Bd. f t .
p r acre
-
-
10.5
30.0
12.2
52.7
9
205
-0.30
0.30
-382
--
--&
0 .4h
132
0.I.h
71
78&3
0.12
.34
993
626
0.06
----
415
9
lillemette N. F.
No. 7
Douglas-fir
Western hemlock
Nestern redcedar
. Total
3
21.0
2 .a
36.3
102.123
0.46
1.619
0.06
Willamstto N. F.
No. 9
Douglas-fir
Western hemlock
Western redcedar
Total
52.3
2.3
7.4
62.0
83,477
1,901
6.763
92. l k l
----
----
0.06
36
0.06
0.06
13
13
.a8
42
-
--
--
A f h r the f i r s t 5 years, there was some adjustment i n plot boundaries end numbered trees.
second -year record do not always agree with the l a s t 2 coluaols i n the f i r s t Fyear record above.
Per sere
26
-0.a
-20
-0.24
123
58
207
-0.38
--
85
-0.06
--
--
0.14
0.20
--
332
0.a
-36
a
0.a
----
u5
--
78
No. of
trees
Bd. f t .
psr acre
0.20
115
837
39,339
10,745
7.092
57.176
19,467
--
8
99
Second
Willamstto U. F.
No. 6
Douglas-fir
Western hemlock
Western redoedar
Total
Per acre
ARnual
nat increment
0.04
0. 2
a
-- .38
.I2
256
190
22
212
-0.80
--
-0.80
I
Reserve stand
5 years
after outting
I
Gross
Gross
volume
No. of
trees
Bd. f t .
per aare
Per aare
Bd. f t .
per acre
9.8
30.0
12.0
51.8
4 O e W
13.0
20.0
2.4
78h
18
-- 2
-9
S O
-
1
660
35.4
459
30.0
3 .O
-1-
10,659
18,701
b.233
101,3g
79,401
676
80.0
n
a4
33.o
25
31
8
11.0
29.7
13.5
54.2
39,463
l0,900
-1,403
12.0
71,406
-1.805
2.
7 -0
93.098
5 years
------
--
34
160
73
267
0.a
----
5
222
2
229
-0.20
-------
347
33
9
4l9
-0.06
---
026
.30
.08
*&
0.14
64
-9
- .Oa.06 -
-0.08
For that reason, the f i r s t 2 ooluma i n the
311
33
16
328
52.0
2.6
7.9
85,030
2.04
6,683
61.6
93.a
10 inches in d i a m e t e r w e r e destroyed. Of a total of 52 t r e e s p e r
a c r e in the r e s e r v e stand, 14 w e r e injured by logging and 38 w e r e
uninjured. The 52 t r e e s had a total volume of 58, 000 board f e e t p e r
a c r e . Windfall and some other mortality resulted in a net l o s s of
about two s m a l l t r e e s p e r a c r e a t the end of 5 y e a r s (9 board f e e t
p e r a c r e p e r y e a r ) on this plot.
During the second 5 y e a r s , growth r a t e increased slightly and
mortality declined, s o that t h e r e was a net increment of 64 board
f e e t p e r a c r e p e r y e a r f o r this period.
Young Douglas - f i r s in the stand that had come in after the f i r e
of some 85 y e a r s ago w e r e tall, slender, and clean boled; a f t e r
partial cutting t h e r e was s o m e l o s s among them continually from
windfall o r snowbreak. The hemlock understory was mostly defec
tive and of bad f o r m , and m o r e than one-fourth of the t r e e s w e r e
injured in logging; they w e r e certainly undesirable a s a r e s e r v e
stand. The cedar was thrifty and appeared to be an excellent
r e s e r v e component, but within 2 y e a r s i t was heavily attacked by
the western cedar b o r e r , , and those c e d a r s l a r g e enough had to be
c u t f o r poles.
-
Except in concentrations of old-growth Douglas -fir and places
where single old-growth t r e e s could be picked out without disturbance, this stand should have been left intact until understory t r e e s
reached merchantable s i z e .
Decadent Old Growth With a Light Understorv
P l o t No. 7, a heavier stand on a slightly better s i t e , supported
a stand of 159,000 board feet p e r a c r e g r o s s volume of highly defective old-growth, mostly Douglas - f i r . Nine l a r g e Douglas -fir t r e e s
p e r a c r e w e r e cut, and about 6 s m a l l hemlock and cedar t r e e s p e r
a c r e w e r e destroyed in logging; their combined volume was 54, 000
board f e e t . This stand was untouched by the f i r e that had burned
plot No. 6. As a r e s u l t , the understory had no Douglas-firs and
only a few hemlocks and c e d a r s of a younger age c l a s s . Growth of
living t r e e s a t the end of the f i r s t 5-year period a f t e r cutting was
256 board feet p e r a c r e p e r y e a r , but mortality from windfall and
other c a u s e s was sufficiently g r e a t to show a l o s s of 660 board feet
p e r a c r e p e r y e a r for the period. In the next 5 y e a r s , the growth
r a t e remained about the s a m e , but windfall increased sharply s o
that the a r e a showed a net l o s s of 1,805 board feet p e r a c r e p e r
year,
Another distressing fact on this a r e a was the nature of the
r e s e r v e stand. Mostly sound t r e e s were cut. The r e s e r v e stand of
m o r e than 100,000 feet p e r a c r e was only 20 percent in completely
sound trees, and about half of the volume was in completely cull t r e e s .
Also, about a q u a r t e r of the r e s e r v e t r e e s w e r e injured, tending in
time to increase the percent of cull. Even though individual t r e e
mortality should decline o r ceas e entirely, decay will i n c r e a s e
because of logging injury, and the stand will continue to go backward.
It appears that this a r e a should have been c l e a r cut.
P u r e Old-Growth Douglas - F i r
P l o t No. 8 was s i m i l a r to plot No. 7, but was m o r e nearly pure
Douglas-fir. Of an original stand of 122,000 board feet p e r a c r e ,
9 t r e e s , about 39, 000 feet, w e r e cut. About a fifth of the r e s e r v e
t r e e s were injured in logging. In the f i r s t 5-year period, growth
on t r e e s left alive was slightly m o r e than 200 board feet p e r a c r e
p e r y e a r , but mortality from windfall and other causes m o r e than
offset the growth. The net l o s s was 444 board feet p e r a c r e per
y e a r . One of the 4 a c r e s -in this a r e a showed a slight gain, the other
3 showed substantial l o s s e s . The lO-year r e c o r d was not available.
Thrifty Middle -Aged Stand of P u r e Douglas - F i r
Plot No. 9 was in a m a t u r e but thrifty stand of Douglas-fir
between 150 and 175 y e a r s old except for a few older wolf t r e e s .
The stand was dense, the boles were well cleared, and the t r e e s
showed no evidence of decay, but they were growing v e r y slowly.
Gentle topography and favorable stand conditions offered an opportunity to make a partial cut that should have resulted in accelerated
growth of high-quality material. on c l e a r boles in the r e s e r v e stand.
C a r e was used in marking to leave good t r e e s well distributed over
the a r e a , but the wolf t r e e s w e r e not taken because they were in
l a r g e openings.
Slightly m o r e than a third of the original stand of 147, 000 board
feet p e r a c r e was removed in the cut. The reaction of this stand to
partial cutting was disappointing, for growth continued to be slow
after cutting. Bark sloughed off o r knocked off by logging caused
d . b. h. measurements to show no diameter growth in the f i r s t
5 y e a r s . Increment borings, however, showed that growth accelerated slightly; the average annual d.b.h. growth before cutting
was 0.04 inches, after cutting nearly 0.05. G r o s s growth was
308 board feet p e r a c r e p e r y e a r . The net growth was 209 feet,
which i s low for this well-stocked Douglas-fir stand that had made
rapid growth in e a r l i e r y e a r s . About a third of the t r e e s in the
r e s e r v e stand were injured by logging. But injuries were slight
and w e r e practically all on Douglas-fir, and for that reason were
considered not v e r y damaging a s Douglas -fir is not highly subject
to decay following injury.
L o s s e s remained about the s a m e for the second 5-year period,
but there was a slight i n c r e a s e in growth r a t e . The net growth p e r
a c r e p e r year was 328 board feet--still far below the average annual
growth (of 840 board feet p e r a c r e ) for the plot during the l i f e of the
stand
.
Summary of West Central Oregon Cascade F o r e s t s
All of these plots were on favorable topography. About a third
of the stand was harvested (mostly from sound trees). A few t r e e s
p e r a c r e in the s m a l l e r diameter c l a s s e s were killed and about a
third of the r e s e r v e stand injured by logging. Even a f t e r cutting,
all plots were still m o r e than fully stocked, although cutting made
for a somewhat uneven spacing. One stand (plot No. 9) was middle
aged, thrifty, and sound; the other three were overmature and
decadent, one of these (plot No. 6) having patches of 85-year hemlock and Douglas - f i r and a well -developed under s tory.
Five y e a r s after logging all three of the overmature a r e a s
showed a l o s s in both number of t r e e s and volume. It amounted to
m o r e than the c u r r e n t growth; in fact, t h e r e was an average net
l o s s of 371 board feet p e r a c r e p e r y e a r . And this does not
include p r o g r e s s of decay o r t r e e s killed by logging. L o s s e s continued during the 5- to lo-year period after logging. T h e r e i s no
indication that l o s s e s had subsided, but even if they had, i t will
take many y e a r s 1 growth to regain the volume already l o s t .
The thrifty, middle -aged stand was confidently expected to
respond to a partial cut, but the acceleration of growth was d i s appointingly slight. Since the r e s e r v e stand i s s t i l l heavily stocked,
it i s probable that a second cut will be n e c e s s a r y to produce any
substantial i n c r e a s e in growth. But this plot did show a net increment and v e r y little l o s s from windfall o r other causes. Stands of
this nature, where growth is on c l e a r boles of sound t r e e s , may
offer r e a l p r o m i s e for a partial o r r e l e a s e cutting, o r may even be
windfirm enough to allow a regeneration cut before a final o r h a r v e s t cut is made. However, there was already considerable brush
development that would hamper restocking.
Northern Oregon Cascade F o r e s t s
Two groups of sample plots representing different conditions
w e r e established on each of two different localities on the Mt, Hood
National F o r e s t (table 6 ) . One group, plots 6 and 7, was n e a r
Parkdale on a d r y s i t e e a s t of the Cascade summit and n e a r the
transition zone from Douglas-fir to ponderosa pine. The other
group, plots 8 and 9, was on Clear C r e e k on the west slope of
M t . Hood in a m o r e typical west-side forest.
A High, Dry Site
The east-side stand was between 150 and 175 y e a r s old and
comparatively sound, but for some time, t r e e s had been dying h e r e
and t h e r e from insect attack, drought, o r some other cause.
P l o t 6 had an original g r o s s volume of 93,000 board feet p e r
a c r e , almost entirely Douglas - f i r , f r o m which about one-third
was cut o r destroyed in logging. About 29 percent of the r e s e r v e
t r e e s sustained logging injuries. An effort was made on this a r e a
to m a r k the low-vigor and badly formed t r e e s for cutting. Growth
was about 370 board feet p e r a c r e p e r y e a r , but mortality from
windfall and other causes was sufficient to offset growth and cause
a net l o s s of 240 board feet p e r a c r e p e r year for the 5,year period.
Plot 7 was s i m i l a r to plot 6 except that i t contained a heavier
mixture of grand f i r . It was given a much lighter cut, 17, 000 feet,
o r 18 percent of the g r o s s volume of 94,000 board feet p e r a c r e .
Growth on this plot amounted to 680 board feet p e r a c r e p e r y e a r .
But mortality nearly offset this good growth r a t e . The %year
period ended with a net gain of 63 board feet p e r a c r e p e r y e a r .
Spot burning for brush disposal was responsible for some of the
mortality. Brush burning injury plus logging damage to the living
r e s e r v e brought the injury figure up to 49 percent of the t r e e s .
At the time of cutting, the stand on both plots showed evidence
of low vigor with dead and dying t r e e s . It was hoped the cut would
salvage these dead and dying t r e e s and r e s t o r e the stand to a thrifty
condition. The plots had an average r e s e r v e stand of nearly
70,000 board feet p e r a c r e . The r e s e r v e t r e e s did appear m o r e
healthy a t the end of 5 y e a r s , but mortality had not ceased, and
the extremely slow diameter growth had accelerated s o little
(0.003 inch) that it was hardly measurable. L a t e r cuts may
r e s u l t in accelerated growth. Visible benefits from this cut were
Table 6.--Original
stand and cut. with annual mortality. cross growth. and net increment during f i r s t 5 years in Northern Oregon Cascade areas.
(Per-acre values are given by species i n number of trees and Soribner mlume.)
Plot location and species
Originnl stand
No. of
trees
Gross
volume
-~ t ~.o o dH. F.
-
No.
I
N
M t . Hood N.
F.
Total
7
- lo.
~ouglas-fir
Grand f i r
Total
Y t . Hood ti. F.
-
Ho. 8
hugha-f ir
Western hemlock
Western redoedar
Silver f i r
Total
-
Bd. f t .
per acre
88.0
1.3
89.3
No. of
trees
Gross
volume
First 5 years
Annual mortality and gross growth
Mortality
Gross growth
Windfall
Other
Gross
Gross
No. of
No. of
Gross
Ho. oP
trees
volume
volume
volume
trees
trees
---- -Per aore
Bd. f t .
per acre
Per aore
Bd. f t .
per acre
Per acre
91,602
1.131
9233
26.7
-26.7
31.40
-31.LJ.10
0.26
217
0.40
0.32
357
0.40
254
--
69
O&O
----
---------
6
Douglas-fir
Grand f i r
W
I
Per aore
Cut or destroyed
M t . Hood N. F.
No. 9
Douglas-fir
western hemlock
Western redoedar
Silver f i r
Western white pine
~0ta1
.06
74.3
8k,li(l
16.3
17.128
0.20
82.6
93,898
16.3
17.128
0.20
17.3
88,962
6.3
2.3
07
3 .O
12.3
32,363
6,445
1,663
361
40.832
5.0
.5
1.0
1.5
17,888
8.0
20,769
. 8.3
26.6
9.427
5q.s~~
1
12.3
57.6
7,353
160,945
12.5
31.5
2.0
37.0
1.5
84.5
39,469
52,815
2,890
10,683
2.161
ioa.oi8
--
--
--
leW
l,7oB
--
46
------------
--
--69
--------
--
--
Bd. f t r
per acre
--
254
Per acre
---
-----
26
171
381
0.66
552
----
----
0.06
0.06
16
16
--------
------
------
-----
--
-----
--
--
----
--
--
0.10
0.10
Annual
net increnmnt
Reserve stand
5 years
after cutting
Gross
No. of
trees
volume
No. of
trees
Gross
volume
Per acre
Bd. f t .
per acre
Per acre
Bd. f t .
per acre
-0.66
-109
58 .O
59,618
371
- 0 "
-0.72
-%L--->-*2--+4
0
59 .O
558
126
-0.60
.26
-0 -86
318
-255
63
Bd. f t .
per acre
362
9
684
121
129
25
317
139
317
-..
128
10
594
-
---
--
-0.06
-0.06
----
-0.10
-0.10
-
121
125
26
301
139
317
--
128
10
594
55.0
7.0
62 .O
11.0
68,935
8.150
77.085
.7
9.0
45.0
57,202
%mm6
5,817
b.511
121.616'
7.5
3
1.O
36.0
1.5
77.0
22.277
53,371
1,180
11.177
2.213
90,218
&*J
the harvesting of the dead and dying t r e e s and the leaving of clear
boles for the addition of new growth. The crowns were not dense,
and i t was hoped that Douglas-fir regeneration would follow this cut.
Some Douglas -fir seedlings did occur in the l a r g e s t openings, but
they a r e low in vigor. There is, however, a thrifty stand of grand
fir and brush coming in. They will probably gain possession of the
understory.
A Watershed Gutting: in Overmature Douglas - F i r
Plots 8 and 9 (table 6) differed from all other a r e a s studied in
that they were in an auxiliary watershed for the City of Portland
water supply in the Bull Run Division of the Mt. Hood National
Forest. F o r that reason, the objective in marking was different
from that on other cuttings, and m o r e c a r e was taken in the logging
operation s o a s to minimize watershed disturbance. The cutting
was light, and only such t r e e s were taken a s would not greatly
break the crown canopy o r cause a heavy accumulation of slash on
the forest floor.
Plot No. 8 consisted of a heavy, old-growth stand of Douglasfir and hemlock with a light mixture of Pacific silver f i r and cedar.
T r e e s were mostly large. The original stand had a total of
161,000 board feet per a c r e , from which 41,000 were removed.
Logging injured 38 percent of the r e s e r v e stand. But windfall and
other mortality for the f i r s t 5-year period were practically negligible. G r o s s growth of living t r e e s amounted to 300 board feet p e r
a c r e per year for the period.
Plot 9 was p a r t of the s a m e general stand. But there, many of
the large, old t r e e s had disappeared from various causes years ago
and had been replaced by small understory hemlock and other tolerant species. Hemlock predominated before cutting; and because
mostly Douglas-fir was cut, Douglas - f i r made up l e s s than onefourth of the stand after cutting. Of the 108,000 boar4 f e e t per a c r e
in the original stand, 21,000, o r 19 percent, were cut. A third of
the r e s e r v e stand sustained some injury during logging. Growth on
this plot was practically double that on the previous one, probably
because of the small number of l a r g e old t r e e s and high number of
young tolerant t r e e s in the lower diameter classes. It amounted to
nearly 600 board feet per a c r e per year during the 5-year period.
There was no windfall or other mortality on the plot during this
5-year period.
Both plots 8 and 9 showed a net gain for the f i r s t 5 y e a r s after
logging, and the lowest mortality of any of the 15 a r e a s studied.
However, no deduction was made for the living decadent t r e e s i n
the stand o r f o r the a c c e l e r a t i ~ nof decay that will r e s u l t from the
logging injury sustained ( 9 % . This c u r r e n t decay will greatly reduce
the annual g r o s s growth &own for these plots. The aim of this cutting was to harvest p a r t of the crop with the l e a s t possible watershed
disturbance o r i n c r e a s e in f i r e hazard. F o r example, l a r g e defective hemlocks with big bushy crowns were not taken. Inferior t r e e s
were taken only if their crowns were small, and they could be
removed without g r e a t disturbance. Although light successive cuts
of this nature may not favor maximum timber production, the operation does indicate that they a r e feasible in this timber and soil type,
if watershed protection i s the p r i m a r y objective. If the cuts were
repeated, the Douglas -fir would soon be eliminated from the stand.
The older and m o r e overmature hemlocks and other tolerant species
would die o r be cut next. If natural succession were not interrupted
by windfall o r some other catastrophe, a climax f o r e s t of hemlock,
cedar, and silver f i r should develop, which should be satisfactory
for watershed purposes ( 5 ) .
-
Northern Washington F o r e s t s
Old-Growth Douglas -Fir With Heavv Mixture of Cedar
One a r e a studied (Mt. Baker permanent sample plot 2) l i e s on
Dan's C r e e k above Darrington, Washington. It is typical of the
overmature stands of Douglas-fir in the middle elevations of the
northern Cascades, except that i t had m o r e than the usual amount
of western redcedar a t the time of cutting. It consisted of v e r y
l a r g e , scattered, old-growth Douglas -fir and cedar t r e e s with a
well-developed understory of western hemlock, s i l v e r f i r , and
w e s t e ~ nredcedar in a l l age c l a s s e s .
The purpose of the cut was to remove the old overmature
Douglas - f i r s and c e d a r s and leave the understory of hemlock,
cedar, and silver f i r for further growth and l a t e r cutting. The
original f o r e s t had a volume of l O 9 , O O Q board feet per a c r e from
which 43,000 feet, o r 40 percent of the g r o s s volume, were
removed by the cut (table 71.
During the f i r s t 5 y e a r s after logging, g r o s s growth averaged
837 board feet p e r a c r e p e r year on t r e e s alive a t the end of the
period. But l o s s e s from windfall and other causes w e r e g r e a t
Table 7.--Ori~irml stand and cut with annual mortality, gross ~rowth, and net increment during f i r s t end second 5 years in northern Washington areas.
(Per-acre values are ~ i v e n
by species i n number of trees and Scribner vollunes.)
1
F i r s t 5 years
Annual mortality and Eras6 growth
Mortality
Gross grodh
Windfall
Other
Gross
No. of
Gross
Gross
No. of
No. of
volume
trees
volum
trees
volume
trees
Cut or destroyed
Orieinal stand
Plot location and species
No. of
trees
Gross
volume
No. of
trees
Gross
volume
Per acre
Bd. f t .
per acre
Per acre
Ed. f t .
per acre
2.2
87.5
27.2
20 J+
137.3
25,552
17,774
58,4!%
7.3M
109.126
1.7
25.8
6.2
6.0
39.7
21.490
2,356
17,695
1.738
43.279
Olympia N. F.
No. 17
Douglas-fir
western hemlock
Western redoedar
Total
34.2
19.2
31.5
84.9
119,740
22,096
15.465
157.301
10.2
3.8
5
18.5
34,030
5,922
2.980
42.932
.a6
2.50
Olympic N. F.
No. 18
Douglas-fir
western hemlock
Western redcedar
Silver f i r
Total
0.7
39.0
8.3
10.0
58.0
9,910
32,334
51,819
8.525
102.588
0.5
2
5.2
5
10.4
9,750
2,365
49,271
327
61.713
0.64
.06
.10
0.80
-- -- -M t . Baker N. F. -No. 2
Douglas-fir
%stern hemlock
Western redoedar
Silver f i r
Tote 1
-
-
1
I
I
I
M t . Baker N. F. - N O . 2
Douglas-fir
Western hemlock
Western redcedar
Silver fir
Total
Reserve stand
5 years
after cuttinp.
j
Per acre
O.lL
.10
--
--28
--
Ed. f t .
per acre
Per acre
--
--
----
230
--
316
0 .21r
?W1
0.56
299
----
.44
5,34
557
1.018
6.916
---
---
----
1.20
--
--
--
261
11
9
------
--
---
i?m
-
Per acre
-0J.h
-.I2
837
-0 .80
353
210
85
-1.20
--
648
.e6
-2.50
.
8
k10
-0.60
0
2%
0.44
371
0.52
60
181
Bd. f t .
par acre
Per acre
Bd. f t .
per acre
85
1%
0.5
59.5
20.4
13.2
93.6
4,074
15.956
h0,751(
6.032
66.816
4,988
347
933
-6.268
18.0
13.2
22.7
53.9
60,768
lh.443
7.820
83.03&
8
71
49
35
lr9
0.2
31.8
3.0
9.0
44.0
200
S,610
2,79b
8.026
. 40,s
--
3
365
375
----
-151
0.20
65
337
60
Ed. f t .
per acre
ab-4
--
-
- .lo
.02
-0.72
I
-
3
107
1
---
I
Reserve s tend
10 years
after cutting
Second 5 years
--
4,074
15,956
40,7%
6.032
66.816
Olympic N. F.
NO. 17
Douglas-fir
Western hemlock
Western redcedar
Tots 1
18.0
13.2
22.7
53.9
60,768
&,&3
7,820
83.031
0.10
No. 18
Olympic N. F.
Douglas-fir
Western herdock
Western redcedar
Silver f i r
Total
0.2
31.8
3.0
9.0
44.0
200
29,610
2,794
8.026
40,630
0.a
2.56
.10
.20
2.90
-
Per acre
0.30
.02
0.5
59.5
20.4
13.2
93.6
-
Bd. f t .
z e r acre
0.50
*a
.16
0.70
*&
.10
0.24
--57
-23
--
1.12
--
320
80
431
167
63
--
0.10
0.lb
40
2.259
143
173
2,615
0.;
.&
0.62
--
100
2
102
--
370
43
152
565
Reserve stand
5 years
a f t e r cutting
Gross
No. of
volume
trees
_Annual
net increment
No. of
Gross
trees
volume
------
----
-----------
9
296
--1.32
- .a
-Ooo2
971
-1.9
446
-0.10
220
121
787
-0.34
--
2 4
83
123
ll20
-- .lk
.lo
-0.a
-2.64
.lo
-o.&
-3.02
-
9
81
47
425
15
k
24
--2,k1540
-- 103
202
-2,760
0.5
52.9
20.3
12.2
85.9
4,120
15.552
43.473
17.5
12.7
22.0
52.2
60,&'7
14.209
8.095
83.151
68.943
--
--
18.6
3.5
6.8
28.9
17,532
2,280
7.018
26,830
enough to reduce the annual growth to a net gain of 194 board f e e t
p e r a c r e p e r y e a r . Growth during the second 5-year period was
somewhat g r e a t e r . L o s s e s from windfall declined subs tantially
and f r o m other causes increased slightly, resulting in a net gain of
425 board feet p e r a c r e p e r y e a r . This is one of the 2 a r e a s wut of
a total of 10 that showed a net gain for both the f i r s t and second
5-year period after logging. The average for the 10-year period
amounts to a net gain of 310 board feet p e r a c r e per y e a r .
The sample a r e a consisted of a block of s i x 1-acre plots
located in the center of a well-protected, moderately steep slope.
Growth varied within this a r e a ; 4 of the 6 a c r e s showed a net gain
a t the end of the period, the other 2 a l o s s . In stand composition,
topography, and treatment, the sample plot was typical of this
l a r g e , partially cut stand, but i t appeared to be exceptionally well
protected from wind. Considerable windfall l o s s was sustained in
p a r t s of the stand outside the plot boundaries. But windfall l o s s e s
w e r e relatively low on the plot. The discrepancy illustrates the
chance of e r r o r in using a single, l a r g e sample. Several welldistributed small samples would probably have shown the windfall
loss,
Old-Growth Douglas - F i r Blowdown
The northern Washington a r e a (Olympic permanent sample plot
17) was located n e a r Cushman Lake, above Hoodsport.
This a r e a supported a typical, heavy, old-growth stand of
Douglas-fir with a light mixture of western hemlock and western
r e d c e d a r . It had a total g r o s s volume of 157,000 board feet p e r
a c r e (table 7). Much of the hemlock and cedar was in the understory
and was under o r just approaching merchantable size.
Windfall had taken much of the old stand and some of the younger
under story. Cutting was planned to salvage the windfallen m a t e r i a l
and to take out enough of the live residual stand to make the operation profitable. The cut amounted to 27 percent by volume of
standing t r e e s . Because of the tangled condition of the stand
resulting from windfall, logging destroyed an estimated 2,000 f e e t
o r m o r e to the a c r e . Breakage and excessive decay in the l a r g e ,
old t r e e s caused many heavy chunks of broken logs and tops to be
l e f t on the ground, This d e b r i s was ideal for development of a
l a r g e b a r k beetle population, and beetles caused heavy l o s s e s i n
the residual stand during logging and the f i r s t couple of y e a r s
thereafter.
This unusual s e t of conditions resulted in the heaviest beetle
and windfall l o s s experienced on any study a r e a . By the time the
5-year examination was made, some beetle-killed timber had been
blown down, and some dead standing and down timber had been
salvaged. Therefore, l o s s e s could not be segregated, and a l l w e r e
listed a s windfall in the table. Growth on live t r e e s during the
f i r s t 5 y e a r s after cutting was m o r e than 600 board feet p e r a c r e
p e r y e a r . But the net l o s s during the period amounted to
6 , 2 6 8 board feet per a c r e p e r y e a r .
During the second 5-year period, l o s s e s from a l l causes declined, and growth increased slightly (to 787 board feet).
Nevertheless, l o s s e s were heavy enough that net growth was only
2 4 boafd feet per a c r e p e r y e a r . The total net l o s s on this a r e a
during the 10-year period since logging amounted to 3, 122 board
f e e t per a c r e per y e a r . If a l l l o s s e s ceased, this a r e a would still
have to grow 1,000 board feet per a c r e per year for the next
31 y e a r s to r e s t o r e the volume it contained in the residual stand
when the cutting operation was complete.
A Two-Story North Olympic Blowdown
One a r e a (Olympic permanent sample plot 18) was located on
Salmon Creek above Blyn, Washington, on the north slope of the
Olympics. This a r e a consisted of an overmature stand of widely
scattered, l a r g e , old Douglas-fir and cedar with a well-developed
understory consisting mostly of hemlock and Pacific silver fir.
It i s typical of the mixed f o r e s t on the northwest slopes of the
Olympic Peninsula,
L a r g e t r e e s had been falling intermittently an this a r e a for
many y e a r s , and after one heavier than usual windfall in the e a r l y
1 9 3 0 ' ~salvage
~
cutting was planned for the a r e a . The plan was to
take out salvable windfalls and p a r t of the r e s e r v e stand. The
understory stand on this t r a c t was sufficient to make a wellstocked, new f o r e s t provided the logging would not seriously damage
the r e s e r v e stand o r open i t enough to a c c e l e r a t e windfall. The
windfalls and about one-half of the living t r e e s , l a r g e and small,
were removed,
Growth was about 650 board feet p e r a c r e per y e a r on the t r e e s
alive 5 y e a r s a f t e r c,utting, But l o s s e s from windfall and other
mortality during this period m o r e than offset the growth. The
r e s u l t was an annual net l o s s of approximately 50 board feet p e r
a c r e for the period,
Unlike most study a r e a s , this stand did not tend to stabilize
and show a reduction in mortality during the second 5-year period.
G r o s s growth was about 400 board feet per a c r e per year on the
r e s e r v e t r e e s that remained alive, But the losses, mostly from
windfall, were sufficiently g r e a t to show a net l o s s of 2,760 board
feet per a c r e per year for the second 5-year period. The net l o s s
f o r 10 y e a r s after logging amounted to 1,405 board feet per a c r e
p e r year. The total l o s s amounted to nearly half of the total r e s e r v e
a f t e r logging. The stand on p a r t of the sample plots had been practically blown flat just before the 10-year examination was made in
the fall of 1946. Shortly thereafter, the a r e a a s a whole was in such
a tangled m a s s that a salvage clear cut was necessary.
Like the Cushman plot, this a r e a indicates that where windfall
l o s s e s have occurred, they a r e likely to continue. It would have
been better forest management to clear cut this a r e a in the beginning,
sacrificing some of the under sized and otherwise unmerchantable
material. It had to be c l e a r cut eventually.
Summary of Northern Washington F o r e s t s
The three a r e a s in this group a r e all heavy old stands with welldeveloped understories of tolerant species. The Mt. Baker a r e a was
on a well-protected slope and had sustained no recent unusual windfall o r other losses. It survived a partial cut without abnormal l o s s
and made a net growth in the 10 succeeding y e a r s . Successive cuts
of this nature may permit many understory t r e e s to reach a better
merchantable size, but in the meantime, the average annual net
growth for this a r e a is not m o r e than a third of what it should be on
this site.
The Cushman Lake and Salmon Creek stands were sustaining
heavy windfall l o s s e s before cutting. These two operations demonstrated that a salvage cut in stands of this nature, taking out windfall and other susceptible t r e e s , did not stabilize the stands. L o s s e s
f r o m windfall and other causes probably will continue a t an accelerated pace until the stand is destroyed if not cut.
South Olympic F o r e s t s
The south Olympic a r e a s had stands somewhat older than the
others; in addition, some temporary plot work was done in the
locality to supplement permanent sample-plot findings. F o r that
reason, the permanent plots a r e summarized jointly (table 8).
Table 8 . - - 0 r i ~ i n a l stand and cut with annual mortality, gross growth, and net increment during f i r s t and second 5 years i n South Olympic area.
(per-acre values a r c given by species i n number of t r e e s and Scribner volume.)
Cut or destroyed
Original stand
Plot location and species
No. of
trees
Gross
volume
-W
I
o
I
No. of
trees
Gross
volume
F i r s t 5 years
Annual mortality and aross growth
l o r t a l i ty
Growth:
Windfall
Other
Gross
No. of
Gross
No. of
Gross
volume
trees
volluae
trees
~ & @ 3
Per acre
Bd. f t .
p e r acre
Per acre
Bd. f t .
per acre
Per acre
Bd. f t .
p e r acre
7.6
38.8
1.3
47.7
99,458
4.7
7.2
.1
12.0
64,671
8,120
12
72.803
O.W
181
51
-
o i p ~ p i cN. F.
NOS. 22,23,&
- Douglas-fir
Western hemlock
Western redcedar
Total
%,9&
8,366
162.786
u
I
I
.&
-0.06
-232
Per acre
Bd. f t .
p e r acre
--
-0.68
0.68
-
Olympic N. F.
Nor. 22,23,24
~ouglas-fir
Western hemlock
Wes tern redcedar
Total
after cuttim
2.6
29.7
1.2
33.5
30,355
43,670
8.496
82.521
1
--
984
-984
-
Per acre
14
-0.02
-72
435
I
[
Bd. f t .
per acre
396
25
Reserve stand
5 years
a f t e r cutting
No. of
~ros;
trees
volume
Annua 1
n e t increment
No. of
Gross
trees
volume
- --0.74
Bd. f t .
per acre
Per acre
-167
-639
25
-781
I
2.8
Bd. f t .
per acre
33,951
28.0
43,649
1.2
32.0
8,480
86.080
I
Second
I
-
I-
5 years
1
I
0.02
.ob
--
0.08
221
55
-276
--
--
O*&
0.24
--
- 82
702
--
8 03
702
724
~k the end of the f i r s t 5-year period, there was some adjustment i n plot boundaries and numbered t r e e s .
account6 f o r the difference i n the reserve stand a t the end of the f i r s t 5 years and the beginning of the second.
This f a c t
-0.02
- -34
--
-0.32
-303
46
3
-254
afte; c u t t i n g
2.5
31.4
1.2
35.1
26,841
43.900
8.512
81.253
Douglas-Fir Stand More Than 500 Years Old in Transition Stage
Each of these three groups of sample plots (Olympic permanent
sample plots 22, 23, and 24) represented somewhat different conditions before cutting, but they were sufficiently similar to permit
averaging. The plots a r e located on the south slopes of the Olympic
Mountains in an a r e a of high rainfall and a good site. The virgin
forest h e r e was old--for the most p a r t m o r e than 500 y e a r s .
Douglas-fir t r e e s remaining from this old forest were very large
and, for their age, were comparatively sound. Tolerant cedar and
hemlock had come in and made up an understory a s the oLd, intolerant Douglas-firs died ( 6 ) . The 3 groups of sample plots,
embracing a total of 10 separate 1-acre plots, had an average g r o s s
volume before cutting of 163, 000 board feet p e r a c r e (table 8).
Forty-five percent, o r 73, (900board feet, was taken out, u s u d l y
the l a r g e s t and best trees that were often m o r e than 60 inches in
diameter. In the process of logging, m o r e than half of the r e s e r v e
stand received some logging injury a t the base, bole, o r crown,
and sometimes in m o r e than one place on the s a m e t r e e . Growth
of living t r e e s during t h e 5 y e a r s after the cutting operation amounted
to 435 board feet p e r a c r e p e r year. This is a low growth r a t e for
a high site, but is understandable when the age of the stand
(500 years) and the density of the r e s e r v e a r e considered. After
cutting, the stand was 90,000 board feet to the a c r e .
Mortality was light from windfall 10s s , but heavier from other
causes in the f i r s t 5 years a f t e r logging. Eight of the 10 a c r e s
showed a net l o s s a t 5 years. The mortality averaged 1,216 board
feet per a c r e p e r year for this period. It was sufficiently high to
offset the growth and cause a net l o s s of 781 board feet p e r a c r e
per year.
Growth increased frorn 435 board feet in the f i r s t 5-year
period to 724 board feet per a c r e per year in the second. Yet
current mortality was sufficient in the second 5-year period to
r e s u l t in a net l o s s of 254 board feet per a c r e per year. In future
years, mortality resulting frorn logging injury and exposure might
be expected to decline o r to cease altogether, but l o s s e s from windfall and other causes a r e rather certain to continue. The average
annual net l o s s was .517board feet per a c r e per year for the f i r s t
10 y e a r s after cutting. No record is available of losses in natural
uncut stands of this character in the immediate locality; therefore,
i t is impossible to evaluate accurately this loss. However, the
l o s s positively establishes the fact that the partial cut in this stand
did not restore it to a thrifty growing condition that would result in
an annual volume increase.
These permanent sample plots were located on one of the larger
national-forest timber -sale areaa. To determine if they were representative of the a r e a a s a whole as to percent of cut, injury, and
losses, additional strip surveys were run in several other parts of
the a r e a . Also, temporary plote were established on parts of the
a r e a to measure the effect of a second and third cut. These
temporary plot records were summarized but a r e not presented in
tabular form.
T ernporary Plot Record of Similar Adjoining Stand
A summary of the strips on the a r e a that had been once cut
over showed that an average of one-fourth of the volume was
removed from an original stand of 96,000 board feet per acre.
Included in the amount cut were a few trees that were destroyed by
logging. The cutting left a reserve stand of 69,000 feet gross volume per acre, 47,000 of .which were hemlock, mostly understory.
The uncut Douglas - f i r waa fairly sound, but the hemlock was not.
It was estimated that the hemlock was more than 25 percent defective (by volurqe). Thirty-five percent of the reserve stand received
some s o r t of logging injury. Some of these injured trees were
already decadent, and some of the uninjured reserve trees were
also decadent. It was estimated that only about 50 percent of the
volume of the reserve stand was in trees that were free from both
logging injury and decay, The a r e a s were cut in 1940 and r e examined in 1944. During this 4-year period of time, mortality
averaged four trees per a c r e , mostly hemlock. This resulted in a
net periodic loss of 2,600 board feet per acre, o r about 650 board
feet per a c r e per year. Although these strip surveys were in somewhat lighter stands with a higher percentage of hemlock, they indicate that cut, injury, and losses on the r e s t of the partially cut area
were quite similar to those reported on the three permanent sample
plots. The permanent sample plots may therefore be considered
valid samples
.
Effect of Second Cut on a Similar Adjoining Stand
In order to measure the effect of a later cut on these stande,
one
part of the tract. This was done in 1944. The original cut was made
in 1939. The amount taken out in the first and second cuts plus a
the timber-sale administrators decided to make a second cut an
small amount destroyed by the logging operation amounted to approximately 40 percent of an original stand of 86,000 board feet per
acre. Mortality for the 5-year period was approximately 1,000 board
feet per a c r e per year. The skidding on this a r e a was done primarily
by tractors. On a few steeper localities, logs were hauled on a contour by tractors to a high line and taken out by the high line. Therefore, most of the logging injury resulted from the skidding by tractors. Originally, i t was anticipated that trees injured in the f i r s t
eut could be removed in the second cut. It was expected that
because the forest would be more open, the second cut would result
in l e s s injury than the first. However, this did not work out in
practice, Many of the injured trees were below merchantable size,
and no additional trees could be removed from this heavy, oldgrowth forest without additional injury to the reserve. A t the end
of the f i r s t cut, 35 percent of the reserve stand was injured.
Although a s many of these injured trees a s possible were taken out,
after the second cut 54 percent of the remaining trees showed logging injury when the operation was completed. It was estimated that
16 percent of the uninjured reserve trees had some decay and that
a similar percentage of the injured trees had decay in addition to
the logging injury. The second cut, then, left a reserve stand of
about 50,000 board feet per acre, only 30 percent of which was in
sound, uninjured trees.
Effect of Third Cut on a Similar Adioinine: Stand
To give further information on the effect of successive cuts in
a heavy stand of this nature, it w a s decided to make a third cut on
one a r e a immediately after the second cut was completed. Normally, a third cut would have been deferred several years. This
a r e a had an original stand of 92,000 board feet per acre, oneseventh of which was old-growth Douglas -fir in large trees. A
quarter of the stand had been removed 5 years previously in a
f i r s t cut. The equivalent of two more quarters was removed in
the second and third cuts, taking out a total of 68,000 feet, o r
approximately 74 percent of the stand. The recorded mortality
during the f i r s t 5-year period, plus a few trees killed in logging,
amounted to 4,800 board feet per acre, o r more than 900 board
feet per a c r e per year. When the third cut was finished, practically all trees more than 20 inches in diameter were gone,
including all Douglas-firs. This left a reserve stand of 36 live
trees per acre, 86 percent injured or defective, or both.
It was anticipated that reproduction would become established
after early cuts, though perhaps of the l e s s desirable, tolerant
species. But a dense forest of l a r g e t r e e s is greatly disturbed by
logging, and most of the reproduction that became established on
this a r e a after the f i r s t cut was destroyed o r injured by the second
o r third cuts. A record of surface conditions showed that in the
3 operations combined, 94 percent of the original forest floor was
either disturbed by logging o r had logging debris piled upon it.
Seventy-one percent of the surface was affected in the final two
cuts. Here reproduction was destroyed; on the small undisturbed
surfaces i t was overly dense--an extremely patchwise and unsatisfactory pattern of natural regeneration. If the 36 r e s e r v e t r e e s
survive, a stand of hemlock reproduction may yet become
established ,
Summary of South Olympic Areas
The selectively cut, old-growth forest in the south Olympics
was sampled by three groups of permanent sample plots to measure
the amount cut, injury, current mortality, and growth. They were
supplemented by temporary plots for further checks of injury and
mortality several years after logging. On a p a r t of this a r e a second and third partial cuts were also made and their effects on the
stand recorded.
F r o m 35 to 50 percent of the r e s e r v e stand on both the p e r manent plots and the other plots sustained logging injury. The
permanent plots for the f i r s t 5 years after cutting showed a net
loss of 781 board feet per a c r e per year; mortality on the other
plots was approximately the same Losses declined on the p e r manent plots in the second 5-year period but did not cease. Annual
net l o s s for the l0-year period was 517 board feet per a c r e .
The second cut revealed i t was not feasible to remove all t r e e s
injured in the f i r s t operation because many t r e e s were too small;
in fact, the second cut increased the injury to the r e s e r v e stand to
a total of 54 percent. A third cut was still m o r e detrimental to
this stand. It increased the amount removed to 74 percent of the
original forest, eliminated the Douglas-fir, and left an inferior
stand of small hemlock t r e e s , most of which had developed in the
understory. Thirty-six live t r e e s p e r a c r e were left, 86 percent
of them injured o r defective, o r both.
Both permanent and temporary plots in this stand indicate that
partial cutting has not produced favorable results. Attempts a t
second and third cuts made conditions worse instead of better.
Mortality on permanent plots was s o g r e a t for the f i r s t 10 y e a r s that
if all l o s s e s ceased a t the end of that period another 10 y e a r s would
be required a t the c u r r e n t growth r a t e to r e s t o r e p a s t l o s s e s . In
other words, 20 y e a r s a f t e r cutting, the r e s e r v e stand would again
contain the volume i t had when the f i r s t p a r t i a l cutting operation
was finished.
Old-Growth Fog Belt F o r e s t s
One a r e a sampled was typical of the o v e r m a t u r e fog belt f o r e s t s of Douglas-fir with much hemlock and s p r u c e and s o m e w e s t e r n
r e d c e d a r in m i x t u r e . This a r e a is south of Quinault Lake in
Washington, on a broad flat that i s low and m o i s t , except for a few
well-drained low ridges and knolls. Once the f o r e s t probably contained a somewhat uniform m i x t u r e of a l l f o u r s p e c i e s , but the
distribution changed a s the f o r e s t advanced in age to i t s 500-yearold stage of o v e r m a t u r i t y a t the time of cutting. Douglas - f i r
appeared to have p e r s i s t e d in g r e a t e r n u m b e r s on the b e t t e r
drained s i t e s , the c e d a r on the m o r e m o i s t s i t e s , and s p r u c e and
hemlock on the s i t e s witli a v e r a g e drainage. F o r many y e a r s
since the stand reached m a t u r i t y the v e r y l a r g e , old t r e e s have been
dropping out, to be replaced by an u n d e r s t o r y of the m o r e tolerant
species i n a l l age c l a s s e s (6). In s o m e p l a c e s , the old stand i s
s t i l l f a i r l y intact; in others, only s c a t t e r e d , old t r e e s r e m a i n . The
existing stand p r e s e n t s t h r e e different compositions, and f o r that
reason, t h r e e s a m p l e blocks w e r e selected, each consisting of
five 1- a c r e plots.
The f i r s t block of sample plots was r e p r e s e n t a t i v e of stands in
which only s p r u c e and hemlock t r e e s r e m a i n - - s o m e v e t e r a n s of the
original f o r e s t , and the r e s t u n d e r s t o r y t r e e s that filled in the stand
a s the y e a r s p a s s e d . The second g.roup of sample plots was r e p r e sentative of stands containing a m i x t u r e of Douglas - f i r , w e s t e r n
hemlock, and w e s t e r n r e d c e d a r , but no Sitka s p r u c e . The third
group of s a m p l e plots r e p r e s e n t e d stands with a few l a r g e , old
Douglas-fir and s p r u c e , a heavy stand of u n d e r s t o r y hemlock, and
a v e r y light m i x t u r e of w e s t e r n r e d c e d a r .
An attempt was made to r e s t o r e this f o r e s t to a d e g r e e of t h r i f t
by taking out a few of the remaining old t r e e s . The p e r c e n t of cut
varied, depending p r i m a r i l y on how many l a r g e , old Douglas-fir o r
Sitka s p r u c e w e r e available f o r cutting.
The s a l e was made and the s a m p l e plots established in 1936,
but a t f i r s t the cutting was only f o r right-of -ways and landings.
Eventually the actual cutting began but was not completed until 1940.
Therefore, growth and l o s s e s f o r the f i r s t five y e a r s do not r e p r e s e n t
values for a full five-year period after logging except on a very small
a r e a where the f i r s t cutting took place.
The Spruce -Hemlock Stand
The spruce-hemlock stand was only moderately heavy (127,000
board feet p e r a c r e ) , and only a very light cut of l a r g e , old spruce
was made. It amounted to l e s s than 20 percent of the g r o s s volume
(table 9, plot 19). Since the stand contained a l a r g e number of t r e e s
in the s m a l l age c l a s s e s and only a light cut was made, the g r o s s
growth on these plots was good; about 1,100 board feet p e r a c r e p e r
year for living t r e e s a t the end
of the f i r s t 5-year period. But wind*
fall and mortality from other causes was s o g r e a t that the t r a c t
showed a net l o s s of 170 board feet per a c r e p e r y e a r .
-
During the next 5 y e a r s , g r o s s growth again was high, averaging
about 1,000 board feet p e r a c r e p e r y e a r . L o s s e s subsided somewhat, but they were still high enough to r e s u l t in a net gain of only
270 board f e e t p e r a c r e p e r y e a r for this second 5-year period.
Thus, in spite of the light cut and l a r g e number of t r e e s in the
younger age c l a s s e s , l o s s e s were sufficiently high to reduce net
gain to 50 board feet p e r a c r e p e r year for the 10-year period a f t e r
the beginning of logging.
Scattered Old Douglas - F i r and Cedar with Hemlock Understory
This three-species stand contained 170, 000 board feet to the
a c r e (table 9, plot 2 0 ) . About 59,000 board feet were removed by
cutting. The cut consisted mostly of very l a r g e Douglas-firs.
G r o s s growth on this a r e a f o r the f i r s t 5-year period averaged
only 500 board feet p e r a c r e p e r year, l e s s than half that of the
spruce-hernlock stand. Mortality was s o heavy that the group of
sample plats showed a net l o s s of 3,100 board feet p e r a c r e p e r year
f o r the f i r s t 5-yeas period after cutting s t a r t e d .
C r o s s growth during the second 5-year period was even l e s s ,
averaging only 340 board feet p e r a c r e p e r year, and l o s s e s continued high. The 5-year period ended with an average net l o s s of
2,430 board f e e t per a c r e per y e a r .
The average annual l o s s for the 10-year period was 2,756 board
feet p e r a c r e for this group of sample plots.
Table 9.--Ori~i?al stund and cut with annual mortality, moss growth, end net increment duri-w f i r s t and second 5 years i n fog-belt area.
(Per-acre values are niven by species i n number of trees and Scribner volume. )
1
Reserve
Plot location and species
-
Olympic N. F.
No. 19
Western heznlock
Sitka spruce
Total
Gross growth
Gross
volume
R r acre
Bd. f t .
ger acre
27.2
26.0
53.2
36,100
91.300
127.400
-
NO. 20
Olympic N. F.
Douglas-fir
Western hemlock
Western redcedar
Total
-
Olympic 11. F.
No. 21
' Douglas-fir
Western hemlock
Sitka spruce
Western redcedar
Total
P.r acre
Per acre
Bd. f t .
per acre
0.2
3 .2
3.4
182
21.539
21,721
.o.&
0.52
567
72
6%
2.6
54.773
2,405
1.760
58.938
0.16
2,Mb
61,964
.2
1 .0
31.0
6,711
17G.ka
5.2
32.4
98,&
36,248
k0,164
2.8
1J.t
2.2
43.4
2.086
176.964
6.4
5.4
Bd. f t .
per acre
4.4
--
24
86,141
-
-
Olppic N. F.
Mo. 20
Douglas-fir
western hemlock
Westarn redcedar
Total
-
Olympic W. F.
No. 21
Douglas-f i r
Western hemlook
Sitira spruce
Western redcedar
Total
--
3,010
0.4
572
0.24
0.0
1,Ca
1.96
.12
1.944
drl
---
0.20
2.08
2.185
0.20
0.56
970
556
z-
3.154
--
Bd. f t .
per acre
Per acre
----
B
s
-0.36
.36
-0.72
-
389
219
170
-0.16
-2.L20
-
451
721
1.172
--
"
-0.80
-3.@81
34
- 0 .
-2.16
.20
1
-2,!&9
-
--
-2.44
0.12
.08
0.20
135
173
308
3.8
18.0
.8
%,937
36.033
5.090
0.08
.12
646
387
--
0 %
22.6
96.060
0.20
1.033
0.s
2.0
20.2
2.2
2f3.530
21,081
14,954
2,150
66,715
---
--
rCOg
--
33
---
--
v-
--
0.56
0.04
230
0.60
-0 .&
230
1lL
0.08
.16
0.24
.--dr
1.730
88
736
-- .
81
905
z%u%e
per acre
-.,
.
25.2
928
501
365
106
12
517
I
per acre
21 .C
46.2
37,971
70.856
104,827
3.8
1 .
.8
22.6
.5,%
2.0
20.2
2.2
--h1822
2;
Ui .8
I
Second 5 years
33.971
70,856
ia4.an
.
--
Gross
volume
No. of
trees
&
0.40
25.2
21.0
46.2
24.8
--
--
Roseme stand
5 years
a f t e r cuttine
01ylnpic N. F.
NO. 19
Western hemlock
sitka spruce
~0ta1
0.b
0.40
o.&
.-..
a
I
253
30
683
Per acre
--
.LC
--
0.20
.32
0.60
BO. f t .
per acre
526
--
21,755
2~422
Psr acre
stand
5 years
~ f t e rcukting
Gross
No. of
trees
vpzum
Annual
net increment
%,937
36,033
28,530
21.081
l4.954
2.150
66.715
Reserve stand
10 yearn
a f t e r cutting
-----
--------------
33
y:
-0.00
F
- -.20
-
&6
3.4
51,710
-1,792
8
-2,430
17.0
.8
21.2
Q,068
341
-0.28
3%
-2
-0.24
431
3%
-0.32
8
774,
-- -- 88
-.a - 2 6 8
-- . -
2.0
19.0
1.8
23.2
5,130
83.3Ct3
28,089
16.927
13,616
2&g
62,820
,
Scattered Old Douglas VFir and Spruce with Hemlock Understory
The g r o s s volume of this stand was 177,000 board feet p e r
a c r e , from which 86,000 board feet, o r about half of the volume,
was removed (table 9, plot 21). The cut was mostly Douglas-firs.
During the f i r s t 5-year period, growth amounted to about 500 board
feet p e r a c r e per y e a r . But l o s s e s from both windfall and other
causes w e r e heavy, and the period ended with a net l o s s of
4,800 board feet p e r a c r e p e r y e a r .
In the next 5 y e a r s , growth fell off somewhat, dropping to
L o s s e s a l s o were lower, s o that
the average annual net l o s s was 780 board feet p e r a c r e p e r year.
F o r the lo-year period, the net annual l o s s was 2,800 board f e e t
per acre,
350 board feet p e r a c r e p e r year.
Summary of Old-Growth Fog Belt F o r e s t s
The t h r e e different conditions of stand composition in the fog
belt were subjected to partial cuts which varied from 17 percent of
the volume on the spruce-hemlock plots to 49 percent on the
4-species plots. All a r e a s showed l o s s e s . The a r e a s having the
highest volume in l a r g e old-growth t r e e s had the heaviest l o s s e s .
Strangely enough, both in the f i r s t and second 5-year periods, the
l o s s e s were not entirely from windfall. Many of the old t r e e s died
standing, and others showed signs of dying from the top down.
T h e r e was no way to identify the cause of this l o s s positively. A
m o s t probable cause i s the sudden i n c r e a s e in exposure of t r e e
crowns in the r e s e r v e stand, but proof i s lacking. L o s s e s were
heaviest on the a r e a where percentage of l a r g e , old t r e e s was highe s t and cutting was heaviest, but considerable l o s s a l s o occurred on
that p a r t of the a r e a with fewer l a r g e , old t r e e s .
Mortality declined in the second 5-year period, but l o s s e s by
no means stopped. A check of individual a c r e s showed that onethird of the a c r e s made a net gain in the f i r s t 5 y e a r s , and twothirds showed a l o s s . S i m i l a r r e s u l t s occurred in the second 5-year
period although the l o s s e s w e r e not s o heavy.
1
Average annual net l o s s for these 3 fog belt stands over the
e n t i r e 10-year period was 1,830 board feet per a c r e . The sprucehemlock plots showed a net gain of 50 board feet p e r a c r e p e r y e a r ,
but this was f a r offset by the net l o s s in the other two stand conditions. Volume was g r e a t before cutting, and even the heaviest cut
(49 percent) left a heavy stand per acre. In the heavy residual
stands, the current gross growth on the different areas varied from
340 to over 1,100 board feet per a c r e per year on trees alive at the
end of 10 years. However, this growth waa much l e s s than the
annual loss.
Scattered, overmature trees, more than 500 years old, were
still common in the stand after cutting. The large trees that were
windfallen or cut left such large holes in the younger residual stand
h t i t became highly subject to windfall, sunscald injury, and other
losses in the years that followed. Although mortality rate decreased
during the second 5 years, there was no assurance that losses would
cease. Even though losses should cease, the forest wodd have to
grow an average of 1,000 board feet per a c r e per year for the next
18 yeare, to regain the volume lost in 10 years. In other words,
28 years after logging started, the volume would once more about
equal that in the reserve s a n d when the f i r s t cutting was completed.
After the f i r s t light windfall on this partially cut area, a salvage
cut was made. Scattered windfalls and a few high-risk trees were
removed, making small openings, but windfall lose increased. Xt
was then proposed to clear cut the a r e a s of heaviest windfall loss,
but the clear cut had not been made a t the time of the lo-year
examination. In the small openings made by salvage cuts, a heavy
stand of brush developed, which will hamper future cutting operations and retard natural regeneration.
T h i s forest was long past maturity, and large trees had been
dropping out of it for perhaps 300 years o r more. There is little
reason to believe that accelerating this opening-up process by a cut
of me-third af the volume would restore this type of stand to a
growing condition. Hemlock, spruce, and cedar are normally shallowrooted species, and Douglas -fir, when growing on a moist site such as
this, is m o r e shallow rooted and l e s s windfirrn than usual. Therefore, it seems more logical that accelerated removal of old trees
would incpease windfall and other losses, and that is what happened
on this a r e a ,
Young-Growth Fog Belt F o r e s t With Scattered Old Trees
I
The stand composition and treatment of a young-growth stand in
the fog belt was markedly different from that in other a r e a s studied.
The tract is located on Youngs River on the northern Oregon coast,
and the sample consists of four 1-acre plots in a block (table 10).
I
Table 10.IOTiginal stand and c u t with annual nmrtality. Eross ~ r o r t h ,and n e t increment d u r i x f i r s t and second 5 years i n a
spruce-hedlook stand. (Psr-acre values a r e riven i n number of t r e e s and Soribmr vulume--1 area comprising
a a r e s not included i n previous suamaries.)
F i r s t 5 years
Original s t r n d
P l o t location and species
So. of
tnes
I
I
Gross
wlums
-Wr acm
Bd. Pt.
Ho. of
trees
Per more
per acre
-
Clatsop
l o . 5 (Youngas River)
western hemlock
Sitka spruoe
Total
511.7
253
80.0
63.611
23.851
87.42
Annual mortality and gross growth
Cut o r destroyad
I
I
Gross
volume
Bd. Pt.
Mortality
Windfall
no. of
Gross
trees
volu~na
Per acre
per acre
8.2
1.0
9 .2
8,245
1.185
25.~0
0
Bd. f t .
p e r acre
Per acre
0.50
:
1.00
Other
No. of
trees
.06
430
0.56
Reserve stand
5 years
after cutlllp
-
Clatsop
lo. 5 (Young's Ri-)
Western hemlook
Sitka spruoe
Total
39.5
10.835
23.5
63.O
66.a
Gross
rolum
Bd. f t .
per acre
Annual
n e t increment
Gmss growth
Gross
No. of
wlumas
trees
Per acre
SO
7
287
----
--
Bd. f t .
p e r acre
975
1.515
No. of
trees
-.
Gross
volume
Bd.ft.
.
-0
per acre
-1.40
a
-1-56
798
- .16
p e r acre
39.5
40,835
5dr
Renerve stand
10 p a r a
a f t e r cutting
Second 5 years
0.14
.20
0.34
Reserve stand
5 years
dtercutting
Gross
Ro. of
volume
trees
-
156
0.10
3h
0.m
805
0.20
615
235
0.4
43
0 .CQ
1,328
0.4k
1,050
38.5
k3s9W
In 19 10, a majority of widely scattered old-growth Douglas -fir
and Sitka s p r u c e t r e e s had been removed from a dense 50-year-old
stand. This young stand was s o dense that the a r e a was still well
stocked after most of the l a r g e old t r e e s were removed. The younggrowth stand, consisting of hemlock and spruce, was partially cut,
a few m o r e of the old t r e e s taken out in 1935, and the sample plots
put in a t that time. If i t were not for the old-growth element in the
stand, the operation could be classed a s a thinning r a t h e r than a
partial cutting in old growth. The average age of the young stand
when partially cut in 1935 was about 75 years; s o m e of the hemlock
was considerably older, and some of the spruce was considerably
younger,
The cut varied from 18 to 51 percent on the 1- a c r e plots, and
averaged 29 percent (table 10). The individual plot r e c o r d s showed
heaviest l o s s e s and lowest growth r a t e for the plots with the heaviest
cut. The l o s s from windfall was double that from other causes.
Total l a s s from a l l causes was almost 500 board feet p e r a c r e p e r
year for the 10-year period.
Increment borings showed no particular acceleration of growth
a f t e r the removal of scattered old t r e e s in 1910, but up to the 1935
cut, the spruce was making m o r e rapid growth than the hemlock.
After the 1935 cut, there was an acceleration in the growth of hemlock, but the growth of individual hemlock t r e e s still did not equal
that of spruce.
Growth of the r e s e r v e stand p e r year for the f i r s t 5-year period
was m o r e than 1,500 board feet p e r a c r e , and for the second, m o r e
than 1, 300 board feet. In spite of considerable windfall and other
mortality, annual net growth was nearly 1,000 board feet p e r a c r e
for the 10-year period.
T h e r e were two l a r g e and two small Douglas-fir t r e e s on the
plots when they were established in 1935. The two l a r g e Douglasf i r s were cut l a t e r . The two s m a l l Douglas -firs remain on the plots,
but their volume was included with that of spruce. Except for these
two s m a l l t r e e s , the 1910 and 1935 cuts have practically eliminated
Douglas-fir and greatly increased the percentage of hemlock in this
stand. While the overall net growth was good, individual plot r e c o r d s
showed that heavy partial cuts w e r e impractical in young sprucehemlock stands because the cutting resulted in heavy mortality f r o m
windfall and other causes and reduced the growth rate. Light cuts
appeared feasible and were associated with rapid growth and no
mortality.
Old-Growth Douglas-Fir With P o r t ~ O r f o r d - C e d a rMixture
One sample of p a r t i a l cutting was studied in the P o r t - O r f o r d c e d a r mixture, a subtype of Douglas-fir, on the P o r t Orford Cedar
Experimental F o r e s t ( P o w e r s , Oregon). Before the cutting the
f o r e s t was a heavy old-growth stand of Douglas - f i r (122,000 board
f e e t p e r a c r e ) with a 25-percent mixture of P o r t - O r f o r d - c e d a r ,
and a negligible amount of hemlock in the understory. The operation differed from others in that only P o r t - O r f o r d - c e d a r was cut.
Two 4 - a c r e plots w e r e established. P l o t No. 1 was destroyed by
roadbuilding and f i r e by the end of the f i r s t 5-year period and
therefore abandoned. P l o t No. 2 was kept intact and maintained
through the second 5 y e a r s after cutting (table 11).
A n a v e r a g e of 27,000 board feet p e r a c r e was cut f r o m the
stand on plot 2. Annual growth of r e s e r v e t r e e s was m o r e than
500 board feet p e r a c r e during the f i r s t 5 y e a r s , but 3 l a r g e
Douglas-firs died during that time. The r e s u l t was an a v e r a g e
annual net l o s s of 770 board f e e t p e r a c r e for the period. In the
second 5 y e a r s , l o s s e s ceased and the t r e e s showed accelerated
growth, making an a v e r a g e annual net i n c r e a s e of over 900 board
feet p e r a c r e .
T h e r e was practically no l o s s of p o r t - O r f o r d - c e d a r in 10 y e a r s .
Increment borings showed that 33 out of 40 c e d a r t r e e s showed
a c c e l e r a t e d growth, 5 showed no change, and 2 showed a slower
growth r a t e a f t e r cutting. L i t t l e o r no Douglas-fir regeneration
c a m e in. But new Port-Orford-cedar regeneration showed up in
the openings, and growth of established reproduction a c c e l e r a t e d .
T h e s e findings indicate that if a p a r t i a l cut w e r e applied m o r e
to Douglas -fir and l e s s to P o r t -Orford-cedar, the percentage of
cedar in the stand would gradually i n c r e a s e , and Douglas -fir
d e c r e a s e . If further t e s t s subs tantiate these findings, the p a r t i a l cutting method might well be applied in the cutting of old-growth
stands if the policy i s to favor P o r t - O r f o r d - c e d a r .
PARTIAL CUTTING IN FRINGE TYPES ON SEVERE SITES
Individual t r e e selection o r even shelterwood cutting may have
a place in s o m e of the abnormal stands o r s i t e s in this region.
Douglas -fir o c c u r s in pure stands o r in mixture with ponderosa pine
and other s p e c i e s in a somewhat all-aged f o r e s t on d r y s i t e s . In
these stands e a s t of the Cascade Range and to s o m e extent in
Table 11.--Reserve st=% d t e r .cut vrith artru33, anortslity, morra mowth. and net incremeat durinRfir.e&[email protected]~5~ gpgp~,sP
in Dwlas-fir
Port-Orford-ceder tme. (Per-acre values me aiven in nunber of trees and bribner volwne-2 are- cqrh.*g,
4???~!8J)
-
Reserve stand
a f t e r cutting
Plot and species
No.of
trees
(
(
Annr~almortality and cross growth
Mortelity
Gross growth
Other
Windfall
Gross
No.of
( Gross
No.of
No.of
I Gross
trees
I volume
volume
trees
trees
I volume
Gross
volume
Per acre Bd. f t .
p e r acre
Per acre
Bd. f t .
per acre
Per ecre
230
56
0.10
070
.46
.5O
1.76
Y
I
C
w
I
Plot No. 1
port-~rfort-cedar
~ouglas-fir
Western hemlock
Other
Totn?
6.5
18.5
3 -8
5.8
35.6
5,804
18,603
836
5,408
30,651
0.20
0.24
286
Plot No. 2
Port-Grford-cedar
~ouglas-fir
Western hemlock
Total
12.0
25.0
1,7
38.7
6,605
87,538
630
94,833
0.04
62
.04
----
--
--
---0.04
Per acre
--
0.a
-273
27
1,339
0.08
132
397
0.20
E1
755
87
-04
416
----
--
--
0.16
1,216
--
62
0.20
1.232
0.34
.04
Bd. f t .
per acre
16
14
19
60
430
5%
Per acre
-- .70
.1;6
-0.30
.
-1.92
-
0.16
-0.16
.10
0.10
12.8
2h.2
2.2
39.2
6.591
83,608
781
90,980
I Gross
(volume
Per acre
Bd, f t .
per acre
338
538
5.0
15.0
4,112
15,912
284
-1,228
5
---
-
1 *5
68
2
786
18
770
ksa
I
26.0
24.511
12 .E!
24.2
2.2
39.2
83,608
78 1
90,980
6,591
1
Reserve stand
~ P t e rc u t t i n g
No. of
trees
$d. f t .
per acre
I
I
Plot No. 2
Port-3ri'ord-cedar
Dougle s - f i r
Western hemlock
Total
Bd. f t .
per acre
Reserve stand
5 years
a f t e r cutting
Annual
n e t increment
Gross
Mo.of
volume
trees
Second 5 yews
--
-
_
I
I
_
_
-
-
_
_
Y
-
_
-
-
-
-
-
Y
_
_
_
-
-
-
-
----
--
--
&f Plot Hoe 1 wae batrayed after the first 5 yews and i s not Lncladsd in tho second 5-year recorb
128
675
112
915
--
o m
.6O
0.74
128
675
112
915
a f t e r cutting
13.5
24.2
5.2
u.9
-
7,321
86,984
1.3&
95,8;5
b
southwest Oregon and on s e v e r e s i t e s within the region p r o p e r , m o i s t u r e i s the limiting f a c t o r . T h e s e stands a r e s h o r t , windfirm, and
somewhat open; they l e t in enough light f o r s o m e Douglas-fir r e p r o duction t o become established and grow. Sample plots w e r e not
located in t h e s e stands in this study, but p a r t i a l cutting o r t r u e s e l e c tion cutting in t h e s e stands was p r a c t i c e d with s u c c e s s e a s t of the
C a s c a d e Range before this p r o j e c t began. T h e r e s e e m s to be no
logical r e a s o n why i t would not be equally successful on the d r i e r
s i t e s of southwest Oregon, the loose, gravelly s o i l s of the Puget
Sound region, o r on s e v e r e south slopes e l s e w h e r e within the
Douglas - f i r region.
Douglas - f i r seedlings become established b e s t under light
shade, but once established they m a k e their b e s t growth and development in full sunlight. T h e r e f o r e , on the d r y o r m o r e s e v e r e s i t e s
w h e r e t r e e s a r e s h o r t and windfirrn t h e r e i s no r e a s o n why this
s p e c i e s would not r e s t o c k b e t t e r under a light shelterwood cutting
than under c l e a r cutting. Once the reproduction i s established, the
overwood should be removed. T h i s recommendation applies only to
the d r i e r , m o r e s e v e r e s i t e s w h e r e t r e e s a r e s h o r t e r and m o r e
windfirm than usual. T h e shelterwood s y s t e m i s not now and never
h a s been recommended by the author f o r a v e r a g e o r b e t t e r s i t e s in
the Douglas -fir region w h e r e stands a r e d e n s e , w h e r e t r e e s a r e
t a l l and shallow rooted, and a r e not windfirm.
SUMMARY A N D DISCUSSION
A s i n g l e - t r e e , p a r t i a l cutting s y s tern was t r i e d under a wide
range of stand conditions in the Douglas r f i r region. S a m p l e plots
w e r e established in national-forest t i m b e r s a l e s f r o m Darrington,
Washing ton, to Oakridge, Oregon, to m e a s u r e the effect of this
type of cutting. Stands v a r i e d in a g e f r o m 150 to m o r e than
500 y e a r s . Species composition v a r i e d f r o m p u r e Douglas-fir to
heavy m i x t u r e s of a s s o c i a t e s p e c i e s , including 2 - s t o r y stands and
stands with a n all-aged u n d e r s t o r y .
T h e cut v a r i e d f r o m l e s s than 20 p e r c e n t to m o r e than 50, and
a v e r a g e d 36 p e r c e n t of the v i r g i n stand by g r o s s volume. M e r chantable t r e e s f r o m the o l d e s t and l a r g e s t s i z e c l a s s w e r e cut;
they w e r e usually Douglas-fir and the b e s t t r e e s in the stand.
The weighted a v e r a g e g r o s s growth of r e s e r v e stands composed
of t r e e s alive 10 y e a r s a f t e r cutting was 555 board f e e t p e r a c r e p e r
y e a r , but this was m o r e than offset by m o r t a l i t y . Two of 15 s a m p l e
a r e a s showed a net gain for both the f i r s t and second 5-year periods,
and 3 m o r e showed a net gain either in the f i r s t o r second period.
Most Douglas -fir and Sitka spruce, usually the oldest t r e e s , either
maintained a uniform growth r a t e o r showed a decline in the 10 y e a r s
a f t e r cutting, compared to the 10 y e a r s before cutting. On the other
hand, most hemlock, cedar, and silver f i r showed an accelerated
growth after cutting.
Annual mortality averaged 1 , 4 9 7 board feet per a c r e . The net
l o s s 10 y e a r s after logging, then, was 941 board feet per a c r e per
year. Some a r e a s appeared to become stabilized during the f i r s t
5 years, but others had the heaviest l o s s e s in the second 5-year
period. Windfall was the g r e a t e s t single cause of loss, exceeding
a l l others combined. If no further l o s s were t o occur after the
10-year period, and i f growth were to continue a t the c u r r e n t r a t e ,
another 15 to 20 y e a r s would be required to r e s t o r e the volume l o s t
during the f i r s t 10 y e a r s a f t e r logging. In other words, 25 to 30 y e a r s
a f t e r cutting the average r e s e r v e stand would have the s a m e vvlurne
a s i t had when the cutting operation was finished. The f o r e s t would
yield no net volume i n c r e a s e in 25 to 30 y e a r s following a partialcutting operation.
Felling aod skidding caused considerable damage to the r e s e r v e
stand. Most skidding was done by the crawler-type tractor, and m o r e
than one-third of the t r e e s received some s o r t of logging injury,
often s e v e r e enough to r e t a r d growth and sometimes s e v e r e enough
to kill the t r e e , A second and third cut on one a r e a indicated that
the percentage of injured t r e e s in the r e s e r v e stand would i n c r e a s e
with each successive light cut in these heavy old-growth f o r e s t s .
A l a r g e percentagz of the r e s e r v e t r e e s were hemlock, true f i r s , OX
spruce. A s e p a r a t e study of decay entrance a f t e r injury to these
species showed that 6 3 percept of the logging s c a r s had decay i x i
t
no
them ( 9 ) . Although decay was p r e s e n t in the 02-igia.al f ~ r e s and
doubt was accelerated by logging injury and sunscald, no volume
deductions were made for decay in the figures shown in this stui?.~.
Therefore, decay l o s s e s , where they occur, will be in addition to
l o s s e s shown in this r e p o r t .
Analysis of r e s u l t s under different stand conditions reveals a
trend toward change in species composition. Where Douglas-Zir
was present, the percentage was reduced by the cut. Sometimes
the Douglas -fir was completely eliminated from the stand. Except
in the l a r g e s t openings, only a few Douglas-fir seedlings were
reported, but none were vigorous enough to be considered well
established. Seedlings of the m o r e tolerant speciesl-hemlock,
grand f i r , silver f i r , and cedar9-were well established in many
stands ,
Sufficient time has not elapsed to determine if an all-age f o r e s t could be developed, but the r e c o r d s to date indicate that the
percentage of Douglas-fir in the stand i s reduced by this type of
cut, and since no regeneration i s becoming established, the species
will eventually be eliminated. If a n all-age f o r e s t can be developed,
i t will contain little i f any Douglas -fir.
Since Douglas .fir is usuqlly the oldest and l a r g e s t element in
a stand, i t will probably be mostly taken out in the f i r s t few partial
cuts. Thus, the peeler logs and other high-grade m a t e r i a l will be
eliminated long before the complete stand is removed, and-the supply of this c l a s s of m a t e r i a l will be exhausted m o r e quickly than if
the f o r e s t were harvested in small, clear-cut blocks, In other
words, light successive p a r t i a l cuts will quickly eliminate highgrade m a t e r i a l from D ~ u g l a s ~ ffiorr e s t s .
.
The r e s u l t s of this study, on the whole, provide f u r t h e r proof
of the accepted hypothesis that an intolerant t r e e like Douglas-fir
i s unsuited for a selection cutting that continuously hakvests the
oldest and r i p e s t t r e e s in an all-aged forest. Nevertheless,
economic situations or silvicultural conditions ( o r a combination
of these) may sometimes justify partial cutting o r even t r e e s election cutting. T h e r e were a few unusual examples on limited
a r e a s in this study where acceptable r e s u l t s were obtained with
p a r t i a l cuts. A m a t u r e but thrifty stand on the Willamette National
F o r e s t (table 5, plot 9) showed no unfavorable effect of partial cutting; growth continued on c l e a r boles a t a slightly accelerated r a t e
f o r the 10-year period following the cut. In a Portland city auxiliary
watershed on the Mt. Hood National F o r e s t (table 6 , plots 8 and 9)
a light cut was made to remove high-value, overmature Douglas-fir.
A net growth with practically no l o s s followed the cut, and there
was no apparent impairment of watershed values; however, t h e r e
was evidence that the cut increased the percent of defect i n the stand
and speeded up the natural transition from a high,grade f o r e s t of
Douglas -fir to a lower grade f o r e s t of tolerant species, Removing
old, s c a t t e r e d Douglas-firs and s p r u c e s and a sma1lqpercentage of
a 75-year-old understory of hemlock and spruce r e s d t e d in good
growth and little l o s s [table 10) in a fog belt a r e a . A partial cut in
a mixed stand of Douglas "fir and Port-Orford "cedar showed that the
cut would favor the P o r t - O r f ~ r d ~ c e d aelement
r
in the .stand (table 101,
a highly desirable s ilvicultural objective in the type.
A partial cut may a l s o be employed successfully to salvage
widely s c a t t e r e d bug-killed timber where the kill is not heavy enough
in one locality o r c o v e r s too l a r g e a n a r e a to justify immediate
c l e a r cutting. N o a r e a was sampled in this study where Douglas-fir
was growing a s an all-aged f o r e s t , o r where t h e r e was evidence that
a n all-aged f o r e s t of Douglas-fir would develop a s a r e s u l t of p a r t i a l
cuts o r any form of individual t r e e selection. However, Douglas-fir
does grow a s an all-aged f o r e s t and i s being managed by selection
cutting in the pine m i x t u r e types e a s t of the Cascade Range on s e m i a r i d s i t e s . T h e r e s e e m s no logical r e a s o n why i t could not be
managed in a s i m i l a r manner in the fringe types on the d r i e r s i t e s
in southwest Oregon, the gravel soils of the Puget Sound region, o r
s e v e r e , southerly exposures elsewhere in the region where m o i s t u r e
and shade a r e c r i t i c a l f a c t o r s ,
CONCLUSION
The partial-cutting system a s studied and reported in this paper
h a s not proved to be a successful method of harvesting the c r o p and
converting the n o r m a l virgin f o r e s t s of Douglas-fir to new or thrifty
stands on the a v e r a g e o r b e t t e r s i t e s in the region. Even under
conditions where it a p p e a r s to offer p r o m i s e , i t i s always associated
with an impending danger of a n unfavorable species change o r l o s s
from windfall, insects, o r a combination of c a u s e s . T h e r e f o r e , any
plan for p a r t i a l cut o r selection cut in the Douglas-fir type should
include a careful study of stand conditions in advance and provision
f o r salvage in the event of s e v e r e l o s s o r catastrophe.
SELECTED LITERATURE CITED
(1) B a k e r , F r e d e r i c k S o
1934. T h e o r y and p r a c t i c e of silviculture.
McCraw-Hill, New York.
502 pp., illus.
(2) B r a n d s t r o m , A. J. F.
1933. Analysis of logging c o s t s and operating methods in the
Douglas f i r region. 117 pp., i l l u s . C h a r l e s L a t h r o p
P a c k F o r e s t r y Foundation, Wash, D. C.
(3) Hawley, Ralph C . , and Munns, E. N.
1950. F o r e s t terminology. 9 3 pp. Society of A m e r i c a n
F o r e s t e r s , Wash. D G C e
(4) I s a a c , L e o A.
1943. Reproductive habits of Douglas -fir. 107 pp. , illus.
C h a r l e s L a t h r o p P a c k F o r e s t r y Foundation, Wash.
D. C c
(5) Kirkland, B u r t P o ,and B r a n d s t r o r n , A .
F.
1936. Selective t i m b e r management in the Douglas f i r region.
122 pp., i-llus. C h a r l e s L a t h r o p Pack F o r e s t r y
Foundation, Wash. D. C.
J
G
( 6 ) Munger, T . T.
1930. Ecological a s p e c t s of the t r a n s i t i o n f r o m old f o r e s t s
to new. Science, 7 2 (1866): 327-332.
(7) Munger, T. T .
1-950. A l o o k a t s e l e c t i v e cutting i n D o u g l a s - f i r .
F o r e s t r y 4862): 97-99,
Jour.
(8) S t e e l e , R o b e r t W e ,and Worthington, Norman P.
1955. I n c r e m e n t and m o r t a l i t y in a virgin Douglas-fir
f o r e s t . Pacific Northwest F o r e s t and Range ExptG
S t a . , R e s . Note 110, 6 p p . , i l l u s . ( p r o c e s s e d )
(9) Wright, E r n e s t , and I s a a c , L e o A .
1955" Decay following logging i n j u r y t o w e s t e r n hemlock,
S i t k a s p r u c e , and t r u e f i r s . Submitted for publication as U, S . Dept. A g r . Tech. Bul.