DEPARTMENT OF LANDS AND FORESTS
BRITISH COLUMBIA FOREST SERVICE
H O N . E . T . KENNEY, M tn tU er

C. D . O R C H A R D , D e p u ty M in ister

THE DEVELOPMENT OF THE

SPRUCE-BALSAM TYPE
in the

AXEZA LAKE EXPERIMENTAL
FCHREST

By
A. R. Fraser and
J. L. Alexander

ECONOMICS DIVISION
F. S. McKINNON, FORESTER

DEPARTMENT OF LANDS AND FORESTS
BRITISH COLUMBIA FOREST SERVICE
H O N . E . T . K E N N E Y , M i„ is le r

C . D . O R C IE Y R D . U r ,,u ly M iiilslir

THE DEVELOPMENT OF THE

SPRUCE-BALSAM TYPE
in th e

ALEZA LAKE EXPERIMENTAL
EOREST

By
A . R . F ra ser and
J. L. A lex a n d e r

ECONOMICS DIVISION
F. S. MeKINNON, FORESTER

TEC H N IC A L PU BLICATION T.32
F i r s t E d i t i o n , 1949

(2,000)

PRICE, 25 CENTS

ACKNOW LEDGM ENTS
Acknowledgment is made to Drs. G. H. Barnes, P. M.
Barr, B. G. Griffith, and R. W. Wellwood, form er members
o f the British Columbia Forest Service, and to several
present members, who were associated with the establish­
ment and remeasurement of the permanent plots used.

T y p i c a i , S p r iic e - B a l s a m

S t a n d . A i. p; z a

L ake

F o b e .s t

E .’iP E R i.M E N T A i. S t a t i o n

TABLE OF CONTENTS
P ag e

Addendum— Additional Data on Incidence o f Decay in White S p ru ce

6

Introduction___________________________

7

Development o f Uncut, Uneven-aged Spruce-Balsam--------------------------------

9

Spruce__________________________________________________________

9

Balsam____________________________

10

-

All Species---------------------------------

10

Liability o f Carrying Balsam _ _______

10

Liability o f Carrying Spruce

12

------------

Development o f Cut-over, Uneven-aged Spruce-Balsam._---------------Importance o f Conserving Advance Growth

13

___

16

Composition o f Next Cut_____________________________________

- 18

Liability o f Carrying Non-productive Balsam and B irch_______

18

Further Examples o f Growth on Cut-over A reas__________
Stands with Adequate Advance Growth

20

.

20

Inadequate Advance Growth____________________________________ 22
Summary o f Volume Production on Cut-over Plots.

--------------------- 23

Even-aged Stands

25

Future Studies________________________

26

Conclusions

—

Literature Cited
Appendix--------------

27
-- 28

-

29

ADDENDUM
A d d it io n a l D a t a

on

I n c id e n c e

of

D ecay

in

W h it e S pruce

Subsequent to the preparation o f this bulletin, additional data on the
incidence o f decay in white spruce became available by courtesy o f the
V ictoria Laboratory, Division o f Botany and Plant Pathology, Science Ser­
vice, Dominion Department o f Agriculture. A continuation o f W aldie’s
study (13) covering all spruce 6 inches D.B.H. and over on 3.6 acres of
samples, all within a 3-mile radius o f the Aleza Lake Experimental Forest
and known to be in the same type, showed the following incidence o f decay
by diameter classes;—
N um ber o f Trees
D.B.H. Class (In.)

P ercentage
w ith Decay

Sound

W ith Decay*

T otal

60

1
1
1

61

1.6

11

6 to 10................
11........................
12......................
13........................
14........................
15........................
16 to 40..............

5
4
4
4
56

6

6
8
10

5
65

121

9.1
16.7
50.0
60.0
55.5
53.7

Totals

143

83

226

6.7

10

4

9

* W ith decay, 85 per cent o f the trees show ing decay had butt-rots varying fro m a tra ce to
advanced stages ; 15 per cent had infection o f the trunk or sapw ood. The table excludes twenty-one
cull trees, sixteen o f which were over 13 inches D.B.H .

Approximately five o f every ten trees over 13 inches D.B.H. have hidden
butt-rots. Waldie showed further that 17.6 per cent o f all trees 11 inches
D.B.H. and over had advanced butt-rots to an extent found in wind-thrown
trees in natural stands, and he concluded that butt-rot does predispose trees
to windfall. W aldie’s standard fo r advanced butt-rot was a shell o f solid
wood 2 inches or less in thickness extending around the circumference o f the
tree at stump height.
In the light o f the foregoing, it is left to the reader to make his own
estimate as to how much less butt-rot would predispose trees to windfall in
selectively cut stands and, hence, how much additional risk is involved
in carrying spruce 13 inches D.B.H. and over in such stands.

The Development of the Spruce-Balsam Type
in the Aleza Lake Experimental Forest

INTRODUCTION
The spruce-balsam (P. glauca, Voss., A . lasiocarpa, Nutt.) forest type
o f the North Central Interior o f British Columbia is one o f the principal
timber reserves o f the Province. The estimated total stand o f merchantable
timber is in excess o f thirty-three billion board-feet (eight and a half billion
accessible by 1937 standards), occupying an area o f four million acres in the
valleys o f the Upper Fraser River and its tributaries (1 1 ). Two important
age-types occur: a first generation, more or less even-aged type character­
ized by an apparent lack o f advance growth and by remnants o f the original
deciduous nurse crop, and a climax type characterized by a heavy stand of
advance growth occurring as an understory. To date, the latter, unevenaged type, has received the most attention and is dealt with in the following
report.
The average stand is composed o f uniform mixtures o f spruce and
balsam in proportions o f about 80 per cent spruce to 20 per cent balsam by
net merchantable volume (14,500 board-feet, B.C. Rule, o f spruce to 3,500
board-feet o f balsam per acre). All age-classes are represented in the
typical forest. Spruce ranges in age up to about 350 years and balsam up
to 250 years (3 ). The spruce is relatively sound, o f medium quality, yield­
ing less than 5 per cent clear lumber. Combined losses through decay and
breakage and utilization in logging are estimated to average 11.5 per cent
(range 3 to 17 per cent) o f the gross merchantable volume (1 3 ). The
balsam, however, is relatively defective, with cult losses averaging 29 per
cent (range 0 to 62 per cent) o f the gross merchantable volume (5 ).
Following completion o f the Grand Trunk Railway (now Canadian
National Railway) through the region in 1914, there developed permanent
forest industries based entirely on the utilization o f the spruce in the type.
Sustaining these industries through cutting regulations designed to main­
tain the full productive capacity o f the region is a m ajor forest problem.
In actual logging practice spruce is cut to a diameter limit o f 12 inches
at breast height. On the average, the volume removed is 10 to 15 M B.M.
per acre, practically a clear cut o f the spruce. Very little balsam is utilized.
The residual merchantable stand is, therefore, predominantly balsam. In
addition, the natural incidence o f species in the understory is four balsam
to one spruce. In the early days, the customary method o f logging, using
horses to skid 16-foot logs, caused 15 to 20 per cent destruction o f the
residual stands. Recent trends, using heavy tractors to skid lengths up to
entire trees, have caused increases in destruction to from 50 to 90 per cent
o f the residual stands (7 ). Generally, slash has not been disposed of, though
some piling has been done in the past. As a result, the cut-over lands vary
N o t e .— F i g u r e s i n p a r e n t h e s e s r e f e r t o l i t e r a t u r e c i t e d .

from devasted to well-stocked residual stands, depending mainly on the
effects o f a uniform cut on a variable virgin stand (12), the relative destruc­
tiveness o f the method o f logging, and the occurrence o f occasional fires.
Studies o f the various factors controlling spruce regeneration in the
type, conducted by Carman (8 ), Barr (4 ), and Griffith (9 ), indicate a
general conclusion that some improvement o f seed-bed conditions is necessary
to favour an adequate proportion o f spruce in future cuts. Barnes (3) and
Pogue (12) however, suggest the low proportions o f spruce in the residual
stands are no cause fo r alarm. Barnes analysed the development o f the
present mature stand. He suggested a cyclic development wherein the
dominant trees had developed to maturity and full crown cover at a rapid
rate and, at the same time, suppressed the younger age-classes. Maturity
was marked by a comparatively short period o f slow, constant growth, fo l­
lowed by rapid weakening and thinning by disease, insects, and wind-throw,
which had the effect o f opening the stand and starting the cycle again by
release o f the understory. The length o f the cycle appeared to be 120 years.
Harvesting the mature spruce somewhat parallels the natural opening o f the
canopy, and Barnes concluded that, where the logging operation destroyed a
minimum o f advance reproduction (not specified, but estimated to be less
than 20 per cent on the areas from which his data were collected), a second
crop, predominantly spruce, would mature in 120 years.
McKinnon (10) summarized the studies prior to 1940 and concluded
that the understory and its conservation was the key to the problems in the
type. He, together with Alexander (1 ), advocated changing the cutting
limit o f spruce from 12 inches D.B.H. to a flexible limit as high as 18 inches
D.B.H. to satisfy the stocking requirements o f individual areas. Alexander’s
study o f the merchantable volume development o f the present mature stands
further indicated that complete removal o f balsam to the absolute minimum
merchantable limit— about 10 inches D.B.H.— ^would be desirable, in an
attempt to utilize all values and, at the same time, reduce susceptibility to
damage from spruce budworm.
The present study traces the merchantable and total cubic-foot volume
development, fo r various periods up to thirty years, on twenty-seven per­
manent experimental plots established in connection with some o f the above
studies in both uncut and cut-over areas. All plots are within the Aleza
Lake Experimental Forest. In the light o f the additional remeasurements
and recent pathological studies (5) (1 3 ), some decisions on conflicting con­
clusions o f previous studies may be possible.
Throughout the study, gross increment or the actual volume o f the solid
new wood added to the stand annually measures the productive capacity o f
the area; mortality is the annual loss o f wood capital or growing stock;
and net increment is the annual change in absolute volume o f growing stock.
Gross increment minus mortality equals net increment. For short periods
o f stand development the new wood added to the trees which die between
the beginning and end o f a period is very small, and gross increment, there­
fore, closely approximates growth on surviving trees. Theoretically, the
productive capacity o f an area can be realized by intensive management.
Actually, we realize the part o f it that is measured by net increment.
Possibilities o f increasing the realized portion o f productive capacity are
discussed. The values in this study do not include any allowance fo r defect.
The tables, presented in the body o f the report, are summaries o f the
average values fo r various groups o f plots studied and are mainly conflned

to total-volume development. The reader is referred to correspondingly
numbered tables in the Appendix fo r more complete stand statistics, includ­
ing numbers o f trees, average diameters, merchantable volumes, and varia­
tions o f individual plots within the groups.
DEVELOPM EN T OF UNCUT, U N EVEN -AG ED
SPRU CE-BALSAM
Table 1 shows the periodic annual mortalities and the net and gross
annual increments in total cubic feet for fourteen ^^^-acre plots from 1928
to 1938 and fifteen %Q-acre plots from 1938 to 1948 in virgin, uneven-aged
spruce-balsam stands.
T a b l e 1.— D e v e l o p m e n t o f U n c u t , U n e v e n - a g e d S p r u c e - B a l s a m —
A leza L ake
N um ber o f Trees
p er A cre

T otal Volum e—-Cu. Ft.
p er A cre

A verage D.B.H .

Basis
Num ber
Plots

Date
All

Spruce

Balsam

All

Spruce

I 232

13.15

10.00

11.71

4,291

Spruce! Balsam
i
1928............
M ortality
(1928-38)
1938............
1938.............
Mortality
(1938-48)
1948............

114
14
111
110

1
1 105
1
1
1
1
1
I
1

!

All

2,127

6,731

1
1

14

1
31
90

1

46
214

11.86
13.45

10.89
9.41

10.95
1 11.80

402
4,476

776
1,609

1,194
1 6,418

14
14

214

13.41

9.47

;1 11.76

4,407

6,374

15

12.61
13.15

1 10.30
:
8.31

11.07
11.06

326
4,675

1,621
!
i
[
343
1 1.541
1
I
1

27
250

1
687
;I 6,601
1
1

15
15

1

1
90
16
116

9
120

i

Balsam

j
i
;1

1

i

1

P e r io d ic A n n u a l I n c r e m e n t s
T otal Volum e— Cu. Ft. p er A cre
p er Y ear
Period

Annual Increm ent
Spruce

N et
....................................
..............
M ortality
Gross......................................

18.5
40.2
58.7

N et.........................................
M ortality...............................
Gross......................................

26.8
32.6
59.4

1928-48.................................... N et.........................................
M ortality
....................
Gross
.....................

22.6
36.4
59.0

1928-38

1938-48

Balsam

1
1

1
1
!
1
1

All

— 51.8
77.6
25.8
— 8.0
34.3
26.3
— 29.9
55.9
26.0

Basis
N um ber
Plots

1
j1
1!

— 31.3
119.3
88.0

14

22.7
68.7
91.4

15

— 4.3
94.0
89.7

N o t e s . — Stand

4 inches plus, ingrow th included.
V olum e, entire peeled stem.
“ A l l ” includes m in or volumes o f other species.
N o deductions fo r defect.

S pruce

Including ingrowth to the 4-inch diameter class, the number o f trees
has increased slightly, 114 to 120, and the average diameter has remained
almost constant at 13.15 inches. The combined effect o f ingrowth and
growth on surviving trees has more than offset mortality, and there has
been an increase in the total volume from 4,291 to 4,675 cubic feet.

The productive capacity o f the spruce has remained relatively constant
at 58.7 to 59.4 cubic feet per acre per year for the two periods 1928-38 and
1938-48. Over the 20-year period the spruce has grown 59.0 cubic feet and
lost 36.4 cubic feet, fo r a net gain o f 22.6 cubic feet per acre per year.
Balsam

Over the 20-year period, balsam has decreased from 2,127 to 1,541 total
cubic feet. The combined effect o f ingrowth and growth on surviving trees
has been less than the mortality losses, which are mainly in trees larger than
average diameter. The productive capacity o f the balsam, as measured by
gross growth, has remained relatively constant at 26 cubic feet per acre per
year fo r each o f the two decades in the 20-year period. Mortality losses
amounting to 55.9 cubic feet, however, have offset new wood production,
resulting in a net loss o f 29.9 cubic feet per acre per year.
A l l S p e c ie s

Including minor volumes o f Douglas fir and hardwoods, in addition to
the spruce and balsam, the productive capacity as measured by gross growth
is 89.7 cubic feet per acre per year, with only small variations from period
to period. Losses through mortality are 94.0 cubic feet, leaving a net growth
o f minus 4.3 cubic feet per acre per year fo r the past twenty years. The
greater variations in mortality, and hence net growth, from period to period,
are believed to be due to overmature trees succumbing to insects during
a minor outbreak o f spruce budworm in the early 1930’s.
These figures illustrate what may be expected in an uneven-aged stand
which contains all age-classes, including overmature. From external appear­
ances the stand is in a static condition. The numbers o f trees, average
diameters, and total volumes are nearly the same to-day as they were twenty
years ago and, except fo r a m ajor disturbance, such as an insect epidemic or
logging, they should be the same twenty years hence. The total-volume
capacity o f the area is, therefore, complete. Actually, however, constant
changes are occurring within the stand. Approximately 90 cubic feet per
acre o f new wood is produced from year to year. A t the same time, capital
volume is reduced by approximately 90 cubic feet per acre per year, through
mortality, to provide room fo r the accumulation o f the new wood. The net
result, with minor periodic variations, is that none o f this growth is netted
or realized because none o f the loss is salvaged. By annual salvage o f the
dead trees only, the full productive capacity o f the area could be realized.
This mortality, however, is distributed throughout the diameter-and-age
distribution o f the stand; some o f it is in unmerchantable sizes— a result of
suppression— and some in merchantable sizes— a result o f overmaturity,
insect damage, or disease. For obvious economic reasons, the full produc­
tivity o f this type cannot be realized at present. Analysis of the growth
(with a view to a system o f management to eliminate the loss in unmer­
chantable sizes as fa r as possible and to salvage the merchantable sizes,
periodically and before cull values accumulate) should lead to the greatest
realization o f production.
L ia b il it y o f C a r r y in g B a l s a m

The greatest deterrent to realizing the full productive capacity o f the
region is in carrying the non-productive balsam part o f the uneven-aged
type. Table 2 shows the last twenty years’ development o f balsam on an
average acre by diameter-groups at the commencement o f the period. The

diameter-classes used in this discussion are the result o f a study o f A lex­
ander’s (1) (2) merchantable board-foot analysis o f the same plots.

Periodic Annual Increm ents
(C u. F t .) , 1928-48
D.B.H . Group, 1928

N et-rG ross
N et

Ingrow th, 1938-48..............................................
Ingrow th, 1928-38..............................................
4 -8 ..........................................................................
9-12 ........................................................................
18-16........................................................................
17-20........................................................................

M ortality

Gross

3.0

Per Cent
100
95
—4
— 150
— 198
— 788

0 .2

5.8

-1 2 .7
— 11.3
— 6.3

21.2

— 2 .8

2.8

3.0
2.1
5.6
8.5
5.7
0.8
......

Sum.........................................................

-2 8 .3

54.0

25.7

— 110

9 in. + .....................................................................

— 33.1

48.1

15.0

— 221

0.1

2 .0
-

17.0
7.1

OC

T otal V olum e (Cu. F t.)

N um ber o f Trees
D.B.H . Group, 1928
1928

M ortality

1948

1928

M ortality

1948

8 in. and under.
9 in. and over...

46.2
58.7

19.1
27.9

89.1
30.8

237
1,852

118
962

334
1,189

Totals.

104.9

47.0

119.9

2,089

1,080

N o t e . — Slight discrepancies

I

1,5

between Table 1 and Table 2 are explained in the A ppen dix.

The risk o f carrying balsam fo r a later cut is obvious. In spite o f
growth on surviving trees, the volume per acre has decreased from 2,089
cubic feet to 1,523 cubic feet. Unfortunately, total values carry the bad
with the good, and entire liquidation o f the balsam may not be indicated.
It is noted that new trees entering the stand are gaining volum e; the group
originally 4 to 8 inches shows little volume change, and all groups over
9 inches are losing volume. Because most o f the mortality in the 4- to 8-inch
class is caused by suppression, the development or lack o f development o f this
group in the virgin stand would not be sufficient evidence to warrant liqui­
dation if it might play a part in some subsequent crop. For the groups over
9 inches in diameter, however, 47.5 per cent o f the number o f trees and
51.8 per cent o f the volume have disappeared in twenty years. The chance
o f selecting a balsam 9 inches and over that will survive a 40-year cuttingcycle is, therefore, slight, and early removal o f this non-productive stock,
as a first step toward realizing a greater part o f the productive capacity, is
indicated. Evidence that balsam over 9 inches do not respond to release
is presented in later sections o f the report. Fifteen cubic feet gross per
year is being added to balsam 9 inches and over in spite o f mortality
decreasing the growing stock in this group by 48.1 cubic feet per acre per
year. O f a total productive capacity for all species on the area o f 89.7 cubic
feet per acre per year, 15.0/89.7 or 16.7 per cent is being wasted in a losing
battle against death o f balsam 9 inches and over. The simple expedient o f
removing all balsam 9 inches and over may allow this value o f 15.0 cubic feet

to be applied to healthier grow ing stock, and the net growth or realized
proportion o f productive capacity would become a positive 15.0 cubic feet
rather than a net loss o f 33.1 cubic feet as at present.
It must be remembered that the immediate diversion o f this 15.0 cubic
feet productive capacity to residual healthy grow ing stock depends entirely
on the presence o f advance growth capable o f utilizing it. I f insufficient
advance growth is present, the removal o f all balsam over 9 inches may open
up the stand to such an extent that brush species will take over unless
artificial measures, such as planting, are taken. On the other hand, leaving
these trees encourages balsam reproduction (5) at the expense o f the pres­
ently more desirable spruce. In the interests o f obtaining full productivity
on desirable species, the balsam should be removed for whatever merchant­
able values it may possess. The importance o f investigating all possible
means o f utilizing balsam 9 inches and over cannot be overemphasized.
L ia b il it y

of

C a r r y in g S p r u c e

The productive capacity o f the spruce part o f the uneven-aged type is
62.5 cubic feet per acre per year. Mortality decreases this by 36.8 cubic
feet annually, leaving a net o f 25.7 cubic feet. As a percentage we are thus
realizing 25.7/62.5 or 41.2 per cent o f the annual production o f new wood.
Table 3 shows the last twenty years’ development o f spruce on an
average acre by diameter-groups at the start o f the period.
T a b l e 3 .— T w e n t y Y e a r s ’ D e v e l o p m e n t o f S p r u c e o n a n

A verage A cre,

BY D i a m e t e r - g r o u p s a t S t a r t o p P e r io d
Periodic Annual Increm ents
(Cu. F t .) . 1928-48
D.B.H. Group, 1928

N et-^G ross
N et

In g row th ...............................................................
In g row th ................................................................
4 -8 ..........................................................................
9-12........................................................................
13-16........................................................................
17-20........................................................................
2 1 + ...........................................................................

2.2
1.5
3.5
5.2
7.4
4.6
1.3

Sum.........................................................

25.7

1
1

N o t e . — Slight

M ortality

Gross

0.1
3.0
4.6
9.0
8.3
11.8

2.2
1.6
6.5
9.8
16.4
12.9
13.1

i
1

36.8

62.5

1
!
1
1
j

Per Cent
100
94
54
53
45
36
10
41

1

discrepancies in values from Table 1 are explained in the A ppen dix.

It is noted that the stands are netting some growth in all diameterclasses. It is difficult to estimate what proportion o f productive capacity
can be utilized. By intermediate cutting o f second-growth stands, 100 per
cent can be approached, though not necessarily economically. By clear
cutting second-growth, untreated stands as soon as they become merchant­
able, we realize about 70 per cent. Certainly, anything under 50 per cent
is unsatisfactory. Accepting this figure tentatively, the removal o f all
spruce 13 inches D.B.H. and over is indicated so that the productive capacity
or ability to produce wood can be diverted to healthier-sized or new trees.
The marginal realized growth o f 53 per cent fo r the 9- to 12-inch D.B.H.
class is accepted, pending further experimentation, to maintain higher per­
centages o f spruce in the dominant crown classes o f the residual stands.

Trees in the 4- to 8-inch class respond to release, indicating suppression as
the cause o f heavy mortality in this class.
The alternative to removal o f all trees over 13 inches is to attempt
removal o f undesirable individual trees. Unfortunately, it is difficult, if not
impossible, to assess the risk o f carrying an individual tree. Hidden buttrots occur in 40 per cent o f all merchantable-sized spruce trees (1 3 ). With
the knowledge that fou r out o f ten spruce are weakened by butt-rots and the
further estimate that less than 50 per cent o f the growth on those trees will
be realized, opening up a stand and exposing large trees to wind-throw, as
in marked selections on short cutting-cycles, does not seem to be a safe
policy. Each time that two 15-inch spruce blow down, one year’s produc­
tion per acre is lost. The removal o f all merchantable-sized spruce is
indicated. As with balsam, however, if the provision o f adequate growing
stock, perhaps including the planting o f new' trees to which Nature can
divert her productive capacity, is not feasible, then retention o f spruce over
13 inches in diameter may be necessary, despite the risk, to ensure a seedsupply fo r a second crop o f this species.
The remainder o f the report deals with stand-development on cut-over
areas, and the comparisons with the development preceding cutting are
noteworthy. The forecasted liability o f carrying spruce and balsam over
13 inches and 9 inches respectively, representing minimum ages o f perhaps
100 to 120 years, is confirmed. Admittedly, cutting to rigid diameterlimits has had little success anywhere in the world as a final system o f
management. It is advocated here as a practical method o f getting rid o f
the predominant overmature elements, thus converting the stands to a
healthier size-and-age distribution which will be more amenable to the
successful introduction o f a true selection system as mature values
accumulate.
DE V E LO PM E N T OF CUT-OVER, U N E V EN -AG ED
SPRU CE-BALSAM
Table 4 shows twenty-nine years’ development following logging o f an
area adjacent and similar to the uncut plots discussed previously. The
data presented were gathered from four %Q-acre plots. The volumes
removed are unknown. Spruce was completely removed to a 12-inch lower
diameter-limit ftwo trees over 12 inches D.B.H. were left on 1.6 acres).
Some sound balsam over 9 inches D.B.H. may have been removed, but an
average o f twenty-three trees per acre over 9 inches were left. Birch is
not generally utilized, although it form s up to 10 per cent o f the total
volume o f the stands. In this case, an average o f eleven birch trees per
acre over 9 inches in diameter were left and influence the development
o f the residual coniferous stand. This area was logged in the winter
months, using horses fo r skidding, and hence damage to residual trees was
probably less than average fo r the region. Table 4 a shows the periodic
annual net and gross increments and annual mortality losses fo r the various
periods studied.

R e s id u a l S t a n d F o l l o w in g H o r se -s k id d in g O p e r a t io n — M i n i m u m D a m a g e t o U n d e r s t o r y

T otal V olu m e (C u. F t.)

A verage D .B .H . (I n .)

N um ber o f Trees
Species
1926

1919

M.

1938

M.

1948

1919

1926

1

1

172
324
22

1 172
324
22

1

25
2

248
693
1 20

22
54
2

1

261
824
20

4.9
5.3
9.0

1 4.6
1 4.8
! 8.9

All species............

518

1 518

1

37

1 961

78

1 1,105

5.4

1 5.0

1

1

M.

1^48

1919

5.3
3.6
10.1

2.0
3.7

6.4
3.9
1 10.6

339
932
259

3.4

1 4.8

1,530

;j
1

4,8
10.6
7.4

!

9.2

4.3

1

M ortality

Gross

N et

7

years

Gross

,

28
509

i
1

941
1 1,107
1
330

1 1,829

555

2,378

j

1926-38 (7 to 19 years
loeerinsr)
..
.....
1938-48 (19 to 29 years after

1

i

Gross

N et

1
1

I

17.7

21.7

i

I
1

!
39.8
77.3

42.1

2.3
1
1
I

1
1
j

77.9

I

1.9

42.4

44.3

4.0

!

3.3

i

1.5

1

5.5

M ortality

45.7

1
1
1

46.2

1
0.6

1

1948

6
116
16

1,714
1,672
365

138

1 3,751

A ll Species

M ortality

N et

a fter

_

]

a fter

II n' J o g ’ tg y i i Ti i i B O ' !^..... .........................

I r t o -o - in c r l

463
1,084
282

B irch

M ortality

/
to

j1

M.

( T o t a l C u b ic F e e t p e r A c r e p e r Y e a r )

Balsam

Spruce

(0

1938

1

T a b l e 4 a .— P e r io d ic A n n u a l M o r t a l i t y a n d N e t a n d G r o s s I n c r e m e n t s

1919-26

M.

1

1

N et

1926

1938

i

S pruce...........................
Balsam ..........................
B irch..............................

I

M.

56.5

11.6

1

68.1

N otes.— A rea logged 1919. A verage o f fou r plots (N o s. 117 to 120) e.stablished during 1926.
Volum es 1919 are fo r trees surviving to 1926 only.
Ingrow th included.
M .=zPeriodic m ortality between ad ja cen t dates.
Stands are too small to have any im p orta n t m erchantable volumes.
N um ber o f trees include those larger than 1 inch D.B.H .

3.5

j

1.6

5.1

137.3

Gross

1

42.7

1
1
1

91.9

1
1

49.8

1 151.1

1
1

90.5

1

13.8

N et Per­
centage o f
Gross

1

The development o f the uncut plots, adding new wood at a rate o f 89.7
cubic feet per acre per year and losing through mortality 94.0 cubic feet, fo r
a net loss o f 4.3 cubic feet, indicated the desirability o f transform ing the
stands to a condition where a major proportion o f the new-wood increment
could be realized. Table 4 a shows that a simple way to achieve this aim is
to remove all economically merchantable trees and release the advance
growth.
The periodic increment shows that the production o f new wood dropped
to 42.7 cubic feet per acre per year in the first seven years following logging,
increased over the next 12-year period to 91.9 cubic feet and, over the period
nineteen to twenty-nine years following logging, jumped to 151.1 cubic feet.
The reasons why the productive capacity o f the cut-over has exceeded that
o f the virgin stand are unknown. Possible reasons include the uncertainty
o f accurate volume estimates fo r small trees and that the productive capacity,
as measured by volume rather than dry weight (the commonest theory), does
not remain constant.
No records o f mortality were kept fo r the first period but, during the
second period, mortality was 46.2 cubic feet per acre per year or 50.2 per
cent (46.2/91.9) o f the wood production and, during the final ten years
studied, mortality was 9.1 per cent (13.8/151.1) o f the wood production.
Study o f the dates covered shows that mortality on the cut-over plots was
heavier in the period 1926-38 than in 1938-48. The observation on the
uncut plots where the same condition existed, that the variation in net
growth may be attributed to blow-down or insect damage rather than growth
conditions which remained constant, indicates that the heavy mortality on
the cut-over during the period 1926-38 has not been caused by logging.
Forecasted liability o f carrying overmature trees should apply to cut-over
areas. Apparent from Table 4, but obscured by total volumes and the
inclusion o f numerous small trees, is the fact that, based on volume, 46.3
per cent o f the spruce, 97.4 per cent o f the balsam, and 92.8 per cent o f the
birch mortality was confined to trees over 9 inches D.B.H. The probability
is again indicated that balsam and birch over 9 inches left at the time o f
logging have little chance o f surviving fo r a subsequent cut and that carrying
large spruce is risky.
Regardless o f absolute values, the net or realized portion o f new-wood
production has increased from less than nothing ( — 4.3/89.7) in the uncut
stand to 90.8 per cent (137.3/151.1) in the cut-over stand fo r the period
nineteen to twenty-nine years after logging. The areas are now fully
stocked, and further increases in production are doubtful. The more satis­
factory condition o f the cut-over area is obvious. The productive capacity
o f the type is now mostly accumulating on healthy advance growth and new
trees. While nothing like 90 per cent o f this growth will be realized over
a long rotation, it is believed 50 to 70 per cent will be without further
treatment: e.g., anticipating mortality by intermediate cuttings (mean
annual increments o f 100-year-old even-aged stands in the region varying
from 60 to 90 cubic feet per acre per year indicate the proportion o f realized
grow th).
I m portance

of

C o n s e r v in g A d v a n c e G r o w t h

An analysis o f the rapid increase in production following logging, to see
how much o f the productive capacity made available by logging was diverted
to advance growth in the form o f released growth and how much was

absorbed by new trees, was made, as follow s: The indicated limits o f 12
inches fo r spruce and 8 inches fo r balsam at time o f logging were taken as
the upper limits and 0.6 inch as the lower diameter-limit fo r advance growth.
Trees left over these limits are termed undesirables, and any trees under
0.6 inch are termed ingrowth. Actually, the ingrowth consists o f advance
reproduction under 0.6 inch and new trees which cannot be separated on
these plots. The arbitrary definitions o f advance growth and ingrowth are
purely for convenience.
Table 5 a shows the annual wood production (gross grow th) of the three
groups outlined above fo r the fou r plots discussed previously.
T a b l e 5 a .— P e r c e n t a g e o f A n n u a l W ood P r o d u c t io n b y R e s i d u a l G r o u p s
( C u b ic F e e t p e r A c r e p e r Y e a r )
Period a fte r L ogg in g
Group at T im e o f L ogg in g

Cu. Ft.

Ingrow th (under 0.6 in.) aver­
age .............................................
A dvance grow th (spruce, 1 to
12 in. : balsam and birch, 1
to 8 in .), average......................
U ndesirables (spruce, 13 in.
p lu s ; balsam and birch, 9
in. p lu s), average.....................

8 to 19 Y ears

0 to 7 Years
Per Cent

20 to 29 Years

Cu. Ft.

P er Cent

Cu. Ft.

P er Cent

3.7

4.0

11.5

7.6

85.8

132.1

87.4

10.2

7.5

5.0

32.5

76.3

78.8

1

10.1

23.7

9.4

1

I

1

N o te .— See Tables 5 and 6a in A p pen d ix fo r com plete com parisons.

T a b l e 5 b .— P r o p o r t io n s o f S p r u c e a n d B a l s a m i n A d v a n c e - g b o w t h C l a s s
Per Cent o f Volum e
Species
1919

1

1926

1938

1948

51.2
48.8

53.6
46.4

1

P lot 117
Spruce
Balsam ......

....... ..................................

I
54.3
45.7

P lot 118

53.6
46.4
j

1

48.0
52.0

I

Spruce
Balsam

51.4
48.6

1
1
1
1

Plot 120
SnriifTP
Balsam....................................................................................

81.5
18.5

S pruce........
Balsam

j

1

Plot 119

43.2
56.8

41.7
58.3

1

50.1
49.9

1
1
49.9
51.1

77.9
22.1

45.5
54.4

I1
1

72.3
27.7

I1

11

48.8
51.2

71.3
28.7

1

By twenty-nine years following logging, 87 per cent o f the volume
production o f the area is on advance-growth trees conserved at the time o f
logging. The undesirables are losing production and the ingrowth show
comparable gains. The areas are now well stocked, and an estimate that
over 95 per cent o f the next merchantable cut will come from the originally
conserved advance growth is indicated. Comparable sites, starting from
bare land promptly restocked, require sixty to seventy years to attain these

volumes. I f an additional 10- to 20-year regeneration period is allowed,
a 50-year gain is indicated by conserving adequate advance growth.
C o m p o s it io n

of

N e x t C ut

A t the present time we are concerned, perhaps unduly, with the pro­
portion o f spruce we may expect in the next crop. Since the bulk o f the
next cut will probably come from existing advance growth on this area, the
proportions o f spruce and balsam in this group should indicate the propor­
tions of each in the next cut (see Table 5 b ) .
On fourteen adjacent uncut plots, spruce averaged 66.5± 4.4 per cent*
in 1928 and 75.1 ± 2.8 per cent in 1948 o f the merchantable spruce and
balsam in the stand. The considerable increase during the 20-year period
is due to the rapid deterioration o f balsam rather than any differences in
growth. On the cut-over plots, where advance growth will provide the basis
fo r the next cut, the proportion o f spruce and balsam remain relatively
constant fo r thirty years following logging.
Concern fo r the composition o f the next cut is really unjustified, in that
balsam normally breaks down at a younger age than spruce. I f sufficient
time is allowed fo r the balsam but not sufficient fo r the spruce to deterio­
rate, a stand starting, say, as 30 per cent spruce and 70 per cent balsam
may end up over 90 per cent merchantable spruce. Contemplated rotations
in the type are much less than the age at which balsam rapidly breaks down
and, without silvicultural measures to increase the proportion o f spruce in
residual stands, proportionately lower percentage and absolute yields of
spruce may be expected than in the present stands. Conserving high-risk
merchantable values— other than seed-trees— to satisfy percentage yields
o f subsequent cuts is not recommended as a silvicultural measure.
L ia b il it y

of

C a r r y i n g N o n - p r o d u c t iv e B a l s a m

and

B ir c h

In the analysis o f the uncut plots it was estimated that 16.7 per cent
o f the productive capacity was being wasted on balsam 9 inches and over.
Alexander (1 ), Bier (5 ), and Dickson (6) have shown these trees to have
merchantable values; however, under present logging practices they are not
removed. Would their removal increase the realized productive capacity o f
the region?
Two 1-acre plots— Plots 291 and 292— were established in 1936 immedi­
ately adjacent to Plots 117 and 118 respectively. On the form er plots all
residual balsam and birch considered incapable o f surviving fo r a second cut
and apparently interfering with the growth o f the advance and new repro­
duction were girdled. The differences in growth on the two pairs o f plots
should indicate the consequences o f removing non-productive balsam and
birch, nineteen years after logging, fo r whatever merchantable values they
may have. Unfortunately, the treatment was not to a rigid plan and the
control-plots were not given a paper treatment in the field; therefore, com­
parisons are difficult. In the following attempt to compare the production
on the pairs o f plots from 1938 to 1948, the check-plots were broken down into
two parts— the productive and the non-productive. In the sense used, non­
productive does not mean that individual trees are not growing, but merely
that, as a group, growth is slow and the risk o f carrying for some subsequent
cut is very high. The same percentage number o f trees, by diameter-classes,
removed on the treated plots were separated on the control-plots and called
* Standard error o f the mean.

non-productive. The remainder or productive part is, supposedly, comparable
to the residual stands on the treated plots. The treatment on the two plots
varied slightly by diameter-classes, but essentially amounted to girdling o f
2 per cent o f the spruce, 100 per cent o f the birch, and 91 per cent o f the
balsam trees over 7 inches in diameter. No trees under 7 inches D.B.H.
were removed. (Observations were that this treatment was too late and
too heavy. The 7-inch trees at first examination, were approximately
4-inch D.B.H., suppressed trees, at time o f logging. Their removal to
eliminate suppression merely releases a new set o f suppressed trees, and
growth, on the particular little areas occupied by the removal o f 7-inch
trees, is set back another nineteen years. That is, the suppressed trees
released may not grow into anything o f better value in nineteen years.)
Table 6 shows comparisons o f Plots 117 and 291 and o f Plots 118 and 292.
T able

6.— E f f e c t o f R e m o v i n g

N o n - p r o d u c t iv e

B alsam

B ir c h

and

FROM C u t - o v e r P l o t s
Periodic Annual Increm ent. 1938-48
(Cu. Ft. per A cre per Y ear)
G ross-i-X

P a rt o f Stand
N et

P lot 117
Productive.........................................
N on-productive (n o t rem ov ed )...

(Cu. F t. per
A cre)
1,313
1,234

P lot 291
Productive.........................................
N on-productive (re m o v e d )..........

1,934
1,418

119.6

P lot 118
Productive.........................................
N on-productive (n o t rem oved) ...

1,039
972

129.2
15.6

P lot 292
Productive.........................................
N on-productive (r e m o v e d )..........

1,345
1,378

131.6

M ortality

Gross

126.8
28.1

Per Cent
9.6
2.3

i

119.7

6 .2

i

........

126.4
28.1
I

0.1

2.2
11.3

!
I

131.4
26.9

132.5

12.8
2.8

!

9.9

I

X r rln itia l volum e o f surviving grow in g stock nineteen to tw enty-nine years follow ing loggin g.
See Table 6 in A ppen dix fo r breakdown by species and other stand statistics.

Because gross growth is the actual volume o f new wood added to a stand
and because, on these plots fo r this period, all o f it was added to surviving
trees, comparisons are on the basis o f gross growth.
R eferring to Table 6 and comparing the gross increments on the pro­
ductive parts o f the stands (126.8 cubic feet with 119.7 cubic feet and 131.4
cubic feet with 132.5 cubic feet per acre per year on comparable pairs o f
plots— 117 with 291 and 118 with 292), no benefits from treatment are
apparent in the ten years following removal o f the non-productive part of
the stand. In fact, if variations in initial grow ing stock on the two pairs
o f plots are considered— by relating gross growth or production o f new
wood to the volume it was added to, i.e., the initial volume o f surviving
trees— the treatment has apparently been detrimental to the first ten years’
growth. The volume increases on untreated plots were 9.6 and 12.8 per cent
annually, compared with 6.2 and 9.9 per cent respectively on treated plots.
This is probably a temporary set-back to the stand, and the benefits o f
treatment, if any, should be apparent after a further ten years’ growth.
Following logging, these stands increased their growths from 42.7 cubic

feet during the first seven years, to 91.9 cubic feet during the next twelve
years, to 151.1 cubic feet per acre per year during the last ten years.
Similar set-backs and increases, though not so pronounced, should result
from the treatments given. The 28.1 and 26.9 cubic feet per acre per year
productive capacities now being wasted on the non-productive parts o f
Plots 117 and 118 are probably diverted on Plots 291 and 292 to trees under
0.5 inch D.B.H., and they will require a few more years to grow before
affecting productive capacity as measured by volume.
Further justification fo r advocating removal o f non-productive balsam
and birch, fo r whatever merchantable values they may have, is apparent in
comparisons o f growth rates o f the two parts o f Plots 117 and 118. Growth
rates o f 2.3 per cent per year compared with 9.6 per cent, and 2.8 per cent
compared with 12.8 per cent fo r the non-productive and productive parts o f
the two plots are shown. On almost equal initial volumes, the productive
part is accumulating new wood over four times as fast as the non-productive
part. Again, some, but certainly not all, o f the difference may be due to
the volume tables.
In spite o f the fact that the treatment was observed to be too late and
too heavy, no real reduction in productive capacity resulted from removal
o f the non-productive balsam and birch, and a future gain is indicated.
While the evidence from these plots may be inconclusive, the weight o f
evidence from other important balsam studies (1, 5, and 6) should be con­
sidered. Balsam over 9 to 11 inches D.B.H., or about 120 years o f age, are
mature and non-productive. They detract from potential growth capacities
o f the region. They suffer abnormally high defect deductions but have some
merchantable values. Leaving them after logging apparently favours bal­
sam reproduction at the expense o f the more desirable spruce. (On rotations
under 150 years this affects the percentage yield o f spruce.) They are most
susceptible to widespread fungous and insect damage. A cut o f the border­
line merchantable values involved is probably not feasible, except at the
time o f logging the more valuable spruce.
The removal o f balsam and birch at the time o f logging to an absolute
minimum merchantable limit, 9 inches D.B.H., is advocated.
F urther E xam ples

of

Grow th

on

Cu t -over A r e a s .

(a) Stands ivith Adequate Advance Growth
Three plots— 148, 149, and 150— were established in 1934 on an area
logged eight years previously to the same standards as the plots already
discussed; i.e., spruce and some sound balsam were removed to a rough
12-inch D.B.H. limit. An average o f twenty-three balsam and nine birch
per acre over 9 inches D.B.H. were left— comparable to twenty-three and
eleven on Plots 117 to 120. The trees were somewhat larger and the stands
more open than is generally found in the region and were characterized by
an apparent lack of seedlings and trees under 1 inch. Eight years after
logging, however, there were 250 to 1,000 trees, compared with over 2,000
per acre on other areas. These differences would be important if larger
advance growth were lacking, in that the seedlings are usually clustered in
small groups, and upwards o f 2,000 are necessary to ensure adequate distri­
bution over an acre. The advance growth, 1 to 12 inches D.B.H. o f spruce
and 1 to 8 inches D.B.H. o f balsam, which now and at the next cut will
provide the bulk o f the volume o f the stand, is slightly larger and better
distributed than on near-by plots.

R e s i d u a l S t a n d F o l l o w in g L o g g in g o f O v e r m a t u r e T y p e

(N ote large balsams left uncut.)

S k id d in g S p r u c e L o gs w it h C r a w l e r T r a c t o r

(P h otogra p h s by F orest P athology Investigations, S cience Service,
Dom inion D epartm ent o f A gricu ltu re, V ictoria, B .C.)

Table 7 is based on the development o f the three plots fo r twenty-two
years following logging.

Periodic A nnual Increm ent
(C u. F t.)
Group a t Tim e
o f L ogg in g

Num ­
ber of
Trees,
1926

Plot
N o.

A ver­
Total
age
Volum e,
D.B.H .,
1926
1926

1926-34

1934-48

Gross

148
149
160

275*
925
775

A dvance grow th (spruce, 1
to 12 i n . ; balsam, 1 to 8
in .)

148
149
150

260
288
293

4.6
4.4
4.5

594
658
709

Undesirables (spruce, over 13
i n . ; balsam, over 9 in .)

148
149
150

25
43

10.7
13.6
16.9

494
1,458
576

Ingrow th (under 0.6 i n .) .......

10

N et

M ortal’y

Gross

0.8
2.5
1.0

0.8

64.4
50.1
47.0

126.3
100.3
94.7

126.3
100.3
104.1

20.0
21.1

—5.6

16.6

—

12.1
2.1

2.5
1.0

9.4
8.5
23.4
15.7

20.6

17.8
13.6

I
* N um ber o f trees under 0.6 inch available fo r ingrow th in 1934.
A rea logged in 1926.
M ortality 1926-34, u n k n o w n ; hence grow th is gross fo r p eriod 1926-34.

Twenty-two years after logging the stands are all fully stocked. From
83 to 88 per cent o f the total annual volume production is being added to the
original 250 to 300 trees per acre o f average diameter 4.5 inches (range—
spruce, 1 to 12 inches; balsam, 1 to 8 inches) at time o f logging. From
11 to 15 per cent o f the productive capacity is being wasted on mature non­
productive trees or undesirables. The remaining 1 to 2 per cent is absorbed
by ingrowth. As the undesirables die off, their productive capacities are
diverted to the ingrowth. Because the so-called advance-growth trees will
provide an estimated 95 per cent or more o f the next merchantable cut, the
indications are that the numbers o f trees in the ingrowth class are not
important if 250 to 300 well-distributed advance-growth trees per acre
remained.
On this area, where an absence o f advance reproduction (under 0.6 inch)
was especially noted, from 300 to 900 trees per acre, eight years after log­
ging, are idling along, available fo r release i f and when required. Having
them on the area makes the stands appear well stocked. I f they were not
present, the stands would appear understocked. Their presence now should
not have any effect on the next cut, and their usefulness may not be appar­
ent until the present th rifty stand has reached a size where a true selection
forest may be developed.
(5 ) Inadequate Advance Growth
Two plots— 45 and 50— were established in an area logged seven years
previously to limits similar to the plots already discussed. On Plot 50,
however, all balsam down to 5 inches D.B.H. were also removed fo r a
heart-rot study (5 ). Although this is an artificial condition, it does give
some indication of how advance reproduction and new trees under 0.6
inch D.B.H. quickly absorb the productive capacity o f the area if enough
advance growth over 0.6 inch is not available. Again, on this area, destruc-

tion from logging was probably a minimum fo r the region as a whole and
longer periods o f waiting may be necessary if destruction were greater.

N um ber
o f Trees
Group
at Tim e o f
L ogg in g

Plot
No.

Ingrovirth (under 0.6
in .)

In­
grow th
1927-48

I
I

A d va n ce
grow th
(spruce, 1 to 12 i n . ;
balsam, 1 t o 8 i n . ;
birch, 1 to 8 in .)

46
50

Undesirables (spruce,
13 in. p lu s ; bal­
sam, 9 in. p lu s ;
birch, 9 in. plus)

45
50

I
I

Periodic Annual
Increm ent (Cu. F t.)

1927

A ver­
age
D .B.H .,
1927

Total
Volume,
1927-34
1927

113
1,028

1934-48

Gross

N et

3.0

1.2
25.1

620
363

3.2
2.5

554
143

53.8
22.2

53
10

13.6
12.9

2,134
235

21.8
1.2

I
I

M ortal­
ity

Gross

1.2
25.1

117.5
55.7

0.5
0.3

118.0
56.0

— 69.1
— 10.1

I 83.8
I 10.7

14.7
0.6

I

The advance growth on Plot 45 was well distributed, and an
adequate residual stand o f advance growth absorbed 88 per cent o f the
productivity o f the area in twenty-two years. About 11 per cent is being
wasted on undesirables. Plot 50 is not up to full production as yet, because
two large openings, slowly restocking, have not had enough time to reach
volume production. The poorly distributed advance growth could not
absorb the full productivity o f the area. The undesirables— ^ten large birch
which are rapidly dying out— are absorbing only a trace o f the productive
capacity. O f an estimated possible capacity o f 130 cubic feet per acre per
year fo r the area, indicated by Plot 45, 56 cubic feet were diverted to poorly
distributed advance growth, and a trace is still being absorbed by the
undesirables on Plot 50. Although there are adequate numbers o f ingrowth
— 1,000 o f average diameter 2.4 inches in 1948— they are absorbing only 25
o f the remaining estimated available 74 cubic feet. This would indicate
that the numbers and sizes o f advance growth are not nearly as important
as an even distribution over the area. The available productive capacity
will be absorbed by these 1,000 trees, but a long period o f competition will
ensue until perhaps the best 200 remain.
Su m m a ry

of

V o l u m e P r o d u c t io n

on

C u t -over P lo ts

Fig. 1 shows the volume production o f all cut-over plots discussed. It
should be borne in mind that all these stands, before logging, had better
than the average stocks o f advance growth general in the region. They
were logged during the winter months, using horses fo r skidding; hence
damage to residuals is believed to have been a minimum. No big openings
fo r skid-roads were created, other than at and around landings; hence the
residual trees were fairly well distributed over the areas.
W ith the exception o f Plot 50, on which the advance growth was pur­
posely removed fo r a heart-rot study, all plots by twenty to thirty years
after logging are producing between 120 and 160 cubic feet per acre per
year, which is believed to be full productivity fo r the type. This growth is
distributed as follow s:—

Fig u r e 1 . _ V o l u m e D e v e l o p m e n t
3000

In g r o w th Gr o u p .
Advance Growth Group. / ,
Tree.? under 0 Bdb.h.
Spro ce/ -/ 2 d b.h. .
ar7d new tri°es.
Ba/samandBirch / - , Sd.b/r.jj
// /
,
N et Vo/umes
ipro
2
<ima
/
to
p
ro
ss
teJy
ecjua
i'o/um.ea
<5/

II<r>
"7~l\yc {/*L
/.iAir\rrcr-iaAnit::')
V /D!o n r\tyj
- / / K 4.
•xoL^cy

n

//in/
;//
1
I

s
u

a

\\

\
\

\\
\

\

n// /

Q

• f

s

p
o

\

/

/

/

J /// ,
'':r

P

P
o
>
p

/ '

o
H

/

J#
r

lO

20

/

/

^ rt ryi rr\
ur

Sprtu ce /3" d b h +
Ba/saim and Bi.rch 3 d.t->.A +
G ro.S - 5 - Vo/i/Av e s .
N eit V olu m e s .

//i
T
' / I / II
/

2000

Pl o t s b y R e s i d u a l G r o u p s .

A //^ A/

-iJ!H
iHii
in I
IJL!
'b

tvS

o f Cu to v e r

\

_____

\\
\S
V \

\

\
-------------------

"S.

________________

'

/

' /

//

-

—

30

a
N u m b er o f

lO

2a

Y ea rs a f t e r L ogg in g .

2o

(а) Advance-growth class; i.e., spruce 1 to 12 inches and balsam
1 to 8 inches D.B.H. at time o f logging. From 80 to 90 per
cent o f the new wood on each plot is being added to the
advance-growth class. O f this new wood, 95 per cent or over
is accumulating as net growth on the 250 to 600 trees in this
class. These trees have a head start on the large numbers o f
trees usually associated with normal stocking o f young stands.
Therefore, the normal conditions o f 2,000 trees being required
on a bare area to produce 300 crop-trees at 100 years and the
terrific losses through competition are obviated to some extent.
The 250 to 600 advance-growth trees should provide 80 per
cent (95 per cent o f the merchantable volume) o f the next cut.
(б ) Non-productive or undesirable class; i.e., trees larger than
so-called advance growth left at time o f logging. From 5 to
15 per cent o f the production on the area is being wasted on
this class. All plots show large net losses over the period
studied, and hope fo r the survival o f any trees in this group
fo r a subsequent cut is slight. It is notable that the greater
the volume o f undesirables left, the greater the net losses.
The merchantable-sized trees are too overmature to try selec­
tion logging.
(c) Ingrowth class; i.e., trees under 0.6 inch at time o f logging or
new trees. From 5 to 15 per cent o f the productivity o f the
area is being added to the ingrowth class. All o f it is now
accumulating as net growth, although this condition may last
only a few years until suppression by the advance-growth class
becomes a factor on all but a very few trees established in
openings. This class should absorb more o f the productive
capacity as the undesirables die off and competition between
poorly spaced advance growth makes it available. However,
except fo r those few trees filling openings, this class is mostly
the difference between the 2,000 trees normally occurring on
bare land and the 300 remaining after 100 years. Again,
except fo r the few filling openings, their presence or absence
should make little difference to the next cut.
EV EN -A G E D STANDS
One plot— 228— was established in a stand o f even-aged spruce-balsam,
S. I. 90, on the Aleza Lake Reserve. Fifteen years’ development from ages
99 to 114 is shown in Table 9.
T a b l e 9.— D e v e l o p m e n t o p E v e n - a g e d S p r u c e - B a l s a m

................

A ge
N um ber o f trees*...................................................
A verage D .B .H .......................................................
T otal volume, cu. ft. (1 in. p lu s)......................
M erchantable volume, cu. ft. (7 in. p lu s ).......
M A I total cu f t
..................

1933

M ortality,
1933-38

99
348
9.1
5.559
4,614
56.2

23
6.5
171
110

1
!
I
1
-

i
♦ Includes ingrow th.

1938

104
328
1
9.6
5,885
' 4,989
56.6

( per A cre)
Mortality,
1938-48

1948

43
7.8
488
367

114
318
10.0
6.451
5.502
56.6

T a b l e 9 .— D e v e l o p m e n t o f

E v e n -a g e d

S p r u c e -B a ls a m

( p e r A c r e ) — Continued

Periodic Annual Increm ents (T otal Cubic F ee t)
P lot N o.

228228-

Period

N et

M ortality

Gross

1933-38
1938-48

65.2
56.6

34.2
48.8

95.4
105.4

22.7

68.7

I 9 1 .4 ± 5 .1

Compare with
102-116 (uneven-afred).

1938-48

I

I

There is little doubt that, from a good forestry standpoint, this evenaged stand is ready to cut. H ow ?— is a problem which requires early
experimentation. The productive capacity o f the region as a whole can be
increased by carrying such even-aged stands, even though they are ready to
cut, while liquidating the uneven-aged type. On the one example, fo r the
comparative period 1938-48, the net accumulation o f wood on the even-aged
stand was 53.7 per cent (56.6/105.4) o f the annual production o f new wood.
On the uneven-aged type it was only 24.8 per cent (22.7/91.4). The differ­
ence in absolute units o f about 30 cubic feet per acre per year applied to the
unknown number o f acres o f even-aged stands which, under present practice,
will be logged during the next twenty years is undoubtedly substantial.
FUTURE STUDIES
The present study is based on groups o f permanent plots established fo r
various completed studies (3, 4, 6, 9, and 10). Periodic remeasurements of
these plots were continued to supply data on growth and yield o f the stands.
It is possible that the main value o f the present analysis is not in the con­
clusions attempted, from basic data not designed to supply such conclusions,
so much as in its usefulness as a guide to the design o f future experiments.
The rigid diameter-limits used in this study are not the best basis fo r
such investigations. They introduce a certain amount o f doubt which may
be overcome only by observations over twenty to thirty years in areas logged
other than to the economic limits now in vogue.
Future studies o f cut-over lands on a permanent-plot basis should start
before logging, so that inform ation on comparative volumes removed,
destruction caused to residual stands, and development in the first critical
years following logging is not obscured by estimates o f destruction and
mortality. W here control-plots are used in multiple-treatment studies, they
should be given duplicate paper treatments in the field so that the develop­
ment o f comparative elements in the various plots can be traced.
The emphasis o f future studies should be on the determination o f the
distributions o f adequate residual stands. Study o f artificial or natural
methods o f obtaining the most desirable composition o f species will be
required fo r cases where removal o f the present overmature values depletes
a stand to a point where supplementary reproduction is necessary to ensure
adequate stocking.
Risk classifications, based on insect susceptibility and the progress o f
decay in individual trees rather than defect o f surviving trees, will be
necessary as the present cut-over stands develop to a point where they may
may be managed as true selection forests.

The economic aspects o f the feasibility o f frequent removal o f low
volumes under a true selection system o f harvesting should be investigated.
Road costs, at least fo r summer logging, may be prohibitive owing to the
usually swampy terrain.
Methods o f treatment fo r the even-aged type require study.
CONCLUSIONS
The conclusions in this report apply specifically to the Aleza Lake
Experimental Forest and generally to similar uneven-aged spruce-balsam
types in the Prince George district. Some care to protect residual stands
has been exercised during logging operations within the Forest and, further,
the winter horse-logging methods used are believed to be representative o f
those causing the least possible destruction to residual stands. The rapid
response o f residual stands within the Forest may, therefore, be representa­
tive o f only the best conditions in the district.
The present virgin stands are producing 90 total cubic feet per acre
per year o f new wood. Losses o f growing stock through mortality (94.0
cubic feet) exceed the production o f new wood, and the net accumulation o f
wood capital is minus 4 cubic feet per acre per year. The over-all loss is
attributed to overmaturity and the resulting higher susceptibility to insect
and pathological losses. Mature values are literally rotting away. All spruce
should be removed to a 13-inch D.B.H. limit, and balsam to the absolute
minimum merchantable limit o f 9 inches D.B.H. The high risk o f carrying
spruce over 13 inches and the prohibitive risk o f carrying balsam over 9
inches is submitted as justification for advocating diameter-limit cutting.
The actual development o f areas logged for spruce only to rough D.B.H.
limits o f 12 inches is submitted to support diameter-limit cutting.
Pro­
ductive capacities for the type o f between 120 and 160 cubic feet per acre
per year are indicated by th rifty well-stocked stands growing on cut-over
areas. This full production was attained on these areas within twenty years
o f logging and is distributed as follow s:—
(a) From 5 to 15 per cent is on non-productive undesirable resid­
uals 13 inches D.B.H. plus fo r spruce and 9 inches D.B.H. plus
fo r balsam and birch. Mortality losses on these groups o f
trees exceed production o f new wood, and net volume losses
occur on all areas. I f two 15-inch spruce are blown down,
one year’s production on 1 acre is lost. Removal o f the non­
productive residuals, at the time o f logging, fo r whatever
merchantable values they may have, is advocated.
(b ) From 80 to 90 per cent is accumulating as net growth on
250 to 600 well-distributed advance-growth trees which were
between the limits o f 1 to 12 inches D.B.H. fo r spruce and
1 to 8 inches D.B.H. fo r balsam at time o f logging. An esti­
mate that over 90 per cent o f the next merchantable cut will
come from this class is tendered. The advance growth o f the
type is sufficient, except perhaps under the most destructive
methods o f logging in a stand with light advance growth, to
utilize nearly the full productive capacity o f the areas.
(c) From 0 to 10 per cent is accumulating on from 1,000 to 2,000
trees which were under 0.6 inch at the time o f logging or
which have subsequently seeded in. This class is capable o f

rapidly utilizing productive capacities made available by
removing undesirable trees if sufficient advance growth is
lacking.
A true selection forest, properly managed, is reputed to net the greatest
volume production o f an area. The spruce-balsam forests o f the Aleza Lake
Experimental Forest contain too many overmature values to be classed as a
true selection forest. The risk o f carrying mature and overmature values
is assessed as too high, even fo r short cutting cycles, on the basis o f uncut
stands. The risk is confirmed by actual development o f such values car­
ried on cut-over areas. This should be sufficient evidence to overcome
scientific doubt on the relative merits o f different kinds and degrees of
cuttings, as yet untried, against diameter-limit cutting. Such cuttings will
involve conserving or holding proven high-risk values which are known to be
rotting away. The opinion is advanced that the low volumes available, fo r
the frequent cuttings that would be necessary to overcome the risk o f carry­
ing such values under other systems o f harvesting, are neither desirable nor
practical. Conversion o f these stands, by removal o f all mature elements
(practically, by diameter-limit cuttings o f spruce to 13 inches and balsam to
9 inches, representing ages o f about 100 to 120 years) and building up the
residual stands to healthy size-and-age distributions, which will be more
amenable to a true selection system o f harvesting, is advocated.
Dependent on the variable residual stands and the period required to
attain complete restocking, volumes o f grow ing stock comparable with the
present stands should accumulate within fifty to seventy years o f logging on
stands within the forest. A t that time the age-and-size distributions should
be such that a silvicultural system may be introduced which can approach
utilization o f the full indicated productive capacity less the current deduc­
tions fo r utilization and defect.
The immediate management problems should be concerned with con­
servation o f advance growth and methods o f obtaining desirable com posi­
tions o f species where supplementary reproduction is required to provide
adequate stocking.
Realized production in the region as a whole can be increased by con­
serving extensive 100- to 120-year-old even-aged stands, now ready fo r
logging, while liquidating the uneven-aged overmature values. Indications
are that net accumulations o f 30 cubic feet per acre per year will accrue on
the acreage o f the even-aged type likely to be logged during the next twenty
years.
LITE R A TU R E CITED
1. A l e x a n d e r , J. L. (1946). A fifteen year history o f Aleza Lake Forest.
British Columbia Forest Service. (Unpublished report.)
2. A l e x a n d e r , J. L. (1946). Balsam in the Northern Interior. British
Columbia Forest Service. (Unpublished report.)
3. B a r n e s , G. H. (1937). The development o f unevenaged stands of
Engelmann spruce, and probable development after logging. Forestry
Chronicle. 1 3 :3 :4 1 7 -5 7 .
4. B a r r , P. M. (1930). The effect o f soil moisture on the establishment o f
spruce reproduction in British Columbia. Yale University School o f
Forestry. Bulletin 26.
5. B i e r , J. E., et al. (1948). Studies in Forest Pathology V. Pub. 804,
Tech. Bull. 66, Dominion o f Canada, Department o f Agriculture.

6. D i c k s o n , F. (1927). A study o f heart-rot in Amabilis fir in the Upper
Fraser Region. Department o f Botany, University o f British Columbia.
(Unpublished.)
7. F r a s e r , A. R. (1948). Tree length logging as a silvicultural problem in
in the Prince George district.
British Columbia Forest Service.
(Unpublished report.)
8. C a r m a n , F . H. (1929). Natural reproduction following fires in Central
British Columbia. Forestry Chronicle 5 :28 -4 4 .
9. G r i f f i t h , B. G . (1931). The natural regeneration o f spruce in Central
British Columbia. Forestry Chronicle 7:4:20 4-19 .
10. M c K i n n o n , F. S. (1940). Spruce regeneration. Forestry Chronicle
16: special number: 38-45.
11. M u l h o l l a n d , F. D . (1937). The forest resources o f British Columbia.
British Columbia Forest Service Report.
12. P o g u e , H. M. (1946). Regeneration and growth o f white spruce. B rit­
ish Columbia Forest Service Report.
13. W a l d i e , C. A. (1948). Interim reports on decay losses in spruce in the
Upper Fraser Region.
(Unpublished report.)
Dom. Lab. Forest
Pathology, Victoria.
A P P E N D IX
The tables presented in the body o f the report are summaries o f the
average values fo r various groups o f plots studied and are mainly confined
to total-volume development. Correspondingly numbered tables in the
Appendix show more complete stand statistics, including numbers o f trees,
average diameters, total and merchantable volumes, and variations o f indi­
vidual plots within the groups.
Table 1.— Development o f Uncut, Uneven-aged Spruce-Balsam.
Table 2.— Twenty Years’ Development o f Balsam on an Average Acre
by Diameter-groups at Start o f Period.
Table 3.— Twenty Years’ Development o f Spruce on an Average Acre
by Diameter-groups at Start o f Period.
Table 4.— Development o f Cut-over Type: Average per Acre o f Plots
117 to 120.
Table 4 a .— Periodic Annual Mortality and Net and Gross Increments.
Table 5.— Development o f Cut-over Type by Residual Groups.
Table 5 a .— Percentage o f Annual Wood Production by Residual Groups.
Table 5 b .— Proportions o f Spruce and Balsam in Advance-growth Class.
Table 6.— Effect o f Removing Non-productive Balsam and Birch from
Cut-over Plots.
Table 7.— Development o f Cut-over Plots 148 to 150 by Residual Groups
(per A cre).
Table 8.— Development o f Cut-over Plots 45 and 50 by Residual Groups
(per A cre).
Table 9.— Development Even-aged Spruce-Balsam (per A cre).

M erchantable Volum e
(Cu. Ft. per A cre)

T otal V olu m e (Cu. Ft.
p er A cre)

A verage D.B.H .

N um ber o f Trees per A cre
Date
Spruce

Balsam

All

S pruce

Balsam

All

Spruce

Balsam

All

Spruce

Balsam

All

Basis
N um ber
Plots

1
1
..............................
................................
.......................................

114
14
111

105
31
90

232
46
214

13.15
11.86
13.45

10.00
10.89
9.41

11.71
10.95
11.80

4,291
402
4,476

2,127
776
1,609

6,731
1 1.194
6,418

3,869
354
4,036

1,935
732
1,466

6,124
1 1,100
5,801

14
14
14

1938
....................................
M ortality (1938-48)
..................................................
1948.......................................................................................

110
9
120

90
16
116

214
27
250

13.41
12.61
13.15

9.47
10.30
8.31

11.76
11.07
11.06

4,407
326
4,675

1 1,621
343
1,541

6,374
687
6,601

3,972
288
4,203

1,480
321
1,350

5,763
624
6,901

15
15
15

1928
M ortality (1928-38)
1938
.

Periodic Annual Increm ents ( Cubic F ee t per A cre per Y ea r)
M erchantable V olum e

T otal V olum e
Spruce

1928-38

1938-48

1928-48

Basis
N um ber
Plots

Annual Increm ent

Period

1
!1

S.E.

Balsam

S.E.

All

S.E.

Spruce

Balsam

All

N et
M ortality
Gross

..................................
................................
—
....................

18.5
40.2
58.7

± 7 .2
± 6 .9
± 5 .0

— 51.8
77.6
25.8

± 1 8 .0
± 1 8 .2
± 1 .8

— 31.3
119.3
88.0

± 1 8 .4
± 1 5 .6
± 4 .1

16.7
35.4
52.1

-4 6 .9
73.2
26.3

- 3 2 .3
110.0
77.7

N et
M ortality
Gross

.........................
...............................
.............

26.8
32.6
59.4

± 5 .2
± 6 .1
± 1 .9

— 8.0
34.3
26.3

± 6 .6
± 5 .0
± 2 .6

22.7
68.7
91.4

± 8 .5
± 7 .1
± 5 .1

23.1
28.8
51.9

— 13.0
32.1
19.1

13.8
62.4
76.2

N et
M ortality
Gross

..................................
.................................................
..................................................

22.6
36.4
59.0

— 4.3
94.0
89.7

± 7 .3
± 8 .4
H-4.4

19.9
32.1
52.0

— 29.9
52.6
23.7

— 9.2
86.2
77.0

1
1
1

— 29.9
55.9
26.0
1

1

14

1
1

15

1

N o t e s . — Stand 4 inches plus.
Ingrow th to 4-inch class included. T otal volume entire peeled stem. M erchantable volume trees, 7 inches plus, 1-foot stump, 3-inch top.
‘ A l l ” includes m in or amounts o f other species. N o deductions fo r defect. E xp erim ental P lot 104 not m easured in 1928.
N ote the reduced variations, as measured by standard errors, o f the gross increm ents. This indicates the desirability o f m aking base predictions on gross values.
A p proxim ate conversion fa c t o r s :—
B oard feet stand 8 inches p lu s = 4 .2 X m erchantable cubic feet 7 inches plus.
or Board feet stand 8 inches p lu s = 3 .8 X to ta l cubic feet 4 inches plus.
F rom com parison with A lexander’ s (7) board feet sum m ary o f same plots in 1928.

N um ber o f Trees

P eriodic A nnual Incre­
m ents (Cu. F t .), 1928-48

T otal V olum e (Cu. F t.)

D.B.H . Group, 1928
1928

M.

M.

1948

1.8

45.2
15.0
28.9

1928

1938

M.

1948

N et

61
41
232
590
603
96

3.0

M.

N et -rGross

Gross
P er Cent

In g row th ................
In g row th ................
4 -8 .........................
9 -12 .......................
13-16.......................
17-20.......................
21

11.4
12.3
5.9

+...............

46.2
38.6
16.6
3.0
0.5

1.6

16.8
34.8
26.3
10.7
1.4

0.3

0.2

0.2

Sum ........
9 in. + ....................

104.9
58.7

31.5

90.2
38.6

15.5
7.8

20.1

5.9
5.7
1.6

0.3

20.6

9.1
1.1
119.9
30.8

57

73
274
260
114
39

23
225
669
529
115
18

42
149
80
28
18

2,089
1,852

760
687

1,579
1,331

320
275

237
845
728
222

2 .8

0.1
5.8
21.2
17.0
7.1
2.8

— 28.3
-3 3 .1

54.0
48.1

2 .0
—

-1 2 .7
— 11.3
-6 .3
—

I 1,523
I 1,189

0 .2

3.0
2.1
5.6
8.5
5.7
0.8

100

95

—4
— 150
— 198
— 788
oc

25.7
15.0

—

110

— 221

I
M .= P e r io d ic m ortality between im m ediately ad ja cen t dates.
The above table is based on a com posite 5.6-acre plot and does n ot check w ith the averages o f the fourteen individual plots because average D .B.H .-height relationships
w ere used fo r the entire area rather than individual curves fo r each p lot at each exam ination . It is o f interest that the values by this short-cut m ethod are w ithin 2 per
cent o f those by individual plots.

M.

1928

TnoTnwtb
Ingrow th
............................................
4 -8
.
9-12.....................................................................................
13-16
..............................
2 1 + ........................................................................ ..............

38.6
24.3
27.7
15.0
8.9

Sum ......................................................................

114.5

[
1

1938

M.

1948

185
540
1,252
1,137
1,114
4,228

5.7
3.4
3.2
0.9
0.7

10.5
32.9
20.9
24.5
14.1
8.2

1.2
4.8
1.1
0.7
1.1
0.9

21.0
9.3
28.1
19.8
23.8
13.0
7.3

13.9

1 111.1

9.8

122.3

1

P eriodic A nnual Incre­
m ents (Cu. F t .), 1928-48

T otal V olum e (Cu. Ft.)

N um ber o f Trees

[

402

Gross

2.2
1.5
3.5
5.2
7.4
4.6
.1.3

0.1
3.0
4.6
9.0
8.3
11.8

2.2
1,6
6.5
9.8
1 16.4
12.9
13.1

25.7

36.8

62.5

1948

N et

22
220
579
1,284
1,202
1,137

3
30
22
37
96
146

43
30
256
645
1,400
1,229
1,140

1 4,444

334

4,743

1938

30
69
143
70
90

1

M.

M.

M.

1928

N et
Gross

P er Cent
100
94
54
63
45
36
10
41

1

M .= P e r io d ic m ortality between im m ediately adjacent dates.
The above table is based on a com posite 5.6-acre plot and does n ot check w ith the averages o f the fourteen individual plots because average D .B .H .-height relationships
w ere used fo r the entire area rather than individual curves fo r each plot at each exam ination . It is o f interest that the values by this short-cut m ethod are w ithin 2 per
cent o f those by individual plots.

T a b l e 4 .— D e v e l o p m e n t o f C u t - o v e r T y p e : A v e r a g e P e r A c r e o f P l o t s 1 1 7 t o 12 0

Spruce
Num ber o f Trees
Plot N o.

1
1
1919 1 1926 1 M.
1
1
1

1938

Basal A rea (Sq. F t.)

M.

1948

1919

1926 I M.
1

A verage D .B .H . (In .)

1938

1
M. 1 1948

i

T otal V olum e (C u. F t.)
1919 1 1926 1 M.
I
1

ii
i
I1 1938
1

M.

1948

200
108
634
516

336
181
613
723

4
44
48
18

852
584
1,005
1,322

4
4
4
11

1,669
1,354
1,628
2,204

339

463

28

941

6

1,714

958
745
488
1,539

jl,134
1 930
1 606
|1,664

381
459
442
754

1,333
1,053
699
1,342

123
118
222

2,008
1,672
1,288
1,718

932

1,084

509

1,107

116

1,672

386
308
255
88

390
368
278
90

70

8
55

......

366
499
340
114

......

420
555
352
132

1

M. 11938
1

M.

1948

1

1

117...................................................
118...................................................
119..................................................
120...................................................

178
190
152
160

178 1 12
190 1 10
152
15
168
5

250
278
205
258

22
35
12
17

298
280
212
255

12.4
7.3
18.2
27.2

18.4 '
11.6
21.6
31.4

0.4
1.4
2.6
0.9

30.1
37.2
50.9

0.4
0.5
0.4
0.7

59.0
51.7
54.5
72.1

M ean.............................

172

172

248

22

261

16.3

20.8

1.3

38.9

0.5

59.3

10

1
1919 11926
1

.....

4.9 1 4.6

4.8

5.3

2.0

11

....

6.4

1

Balsam

CO
CO

117...................................................
118...................................................
119..................................................
120..................................................
M ean.............................

11

300 } 300 1 1 5
345 1 345 1' 27
320
320
27
332
332
32

548
680
802
742

32
67
70
47

645
808
1,008
835

324 1 324

693

54

824

25

35.9 1 45.2
29.4
38.9
21.9
28.4
50.9
57.8

11.7
13.7
14.5
22.4

55.8
52.3
41.7
54.6

34.5

15.6

51.1

42.6

0.2
5.4
5.0
5.9

76.6
72.2
63.4
70.0

4.1

70.6

n .s
17.1
12.6
3.9

0.5
2.0
....

13.1
18.9
12.9
4.7

1

.... 11 .....
..... 11 ..... ,

5.3

4.8

10.6

3.6

3.7

3.9

i

Birch
1
1
20 1 20
5
32
32
28
28
3
8 1 8

15
32
25
8

5
3

M ean.............................

22 1 22

2

20

Mean, all species........

618

37

961

117..................................................
118..................................................
119...................................................
120................-.................................

618

1
1
22
27
22

ij

1

12.6
12.8
10.2
3.2

2.4

8

12.2
11.0
9.4
3.0

2

20

8.9

9.7

0.6

11.3

0.6

12.4

9.0

8.9

7.4

10.1

7.4

10.6

259

282

18

330

16

365

78

1,105

59.7

73.1

17.5

101.3

5.2

142.3

5.4

5.0

9.2

4.3

3.4

4.8

1,530

1,829

555

2,378

138

3,751

A rea logged, 1919. Plots established, 1926.
Volumes 1919 are fo r trees surviving to 1926 only.
Ingrow th included in each exam ination.
M .= P e r io d ic m ortality between adjacent dates.
Stands are too small to have any im portant m erchantable volumes.

....

N et

M ortality

Gross

N et

A ll Species

B irch

Balsam

Spruce
P lot
N o.

M ortality

Gross

N et

M ortality

Gross

N et

M ortality

N et-^
Gross

Gross

P e r Cent
1919-26 (0 to 7 years a fte r l o g g in g ).....

CO

M ean................................................
1926-38 (7 to 19 years a fter lo g g in g ) ....

......
117
118
119
120

Mean................................................
1938-48 (19 to 29 years a fter lo g g in g )..

M ean................................................

117
118
119
120

25.2
26.5
16.9
17.9

1

.....

1 21.7

1

31.8
38.2
36.8
62.8

48.4
48.4
44.6
36.0

— 2.0
10.9
5.2
2.0

44.3

4.0

67.4
74.3
70.7
59.8

5.4
5.6
1.2
1.8

68.1

3.5

j
1
1
j

19.4
10.3
11.3
29.6

117
118
119
120
1

17.7

......
43.1
33.6
32.7
49.9

0.3
2.9
4.0
1.5

43.4
36.5
36.7
51.4

16.6
10.2
7.8
-2 6 .8

1 39.8

1

2.3

42.1

1.9

81.6
77.0
[ 62.3
1 88.2

1

0.4
0.4
0.4

82.0
77.4
62.7
89.3

67.4
62.0
58.9
37.6

77.9

56.5

77.3

1
1
1
1

1-1
0.6

1

42.4

1
1

12.3
11.8
22.2

j

11.6
i

3.3

......

45.2
45.5
31.5
49.8

j

......
38.0
41.1
40.8
64.3

95.7
95.8
86.5
89.4

1

46.2

91.9

1
1

0.4
13.5
17.7
23.3

154.8
158.1
140.1
150.9

13.8

151.1

...

...
1

3.9
10.9
5.2
2.0

......
57.7
54.7
45.7
25.1

5.5

45.7

0.8
5.5

5.4
6.4
6.7
1.8

154.4
144.6
122.4
127.6

1.6

5.1

137.3

5.9

1

0.6
8.7
3.3
0.3

1.5

1

1

42.7

1

......
49.8

90.5

T a b l e 5 .— D e v e l o p m e n t o f C u t - o v e r T y p e b y R e s i d u a l G r o u p s
P eriodic Annual Increm en t (C u. Ft.
p er A cre p er Y e a r)
Num ber o f Trees (S ., B., and B i.)
Group at Tim e o f L og g in g in 1919

T otal V olum e (C u. Ft. p er A cre )

1919-26

Plot
No.

1938-48

1926-38
1919

1926

M.

1938

M.

1948

1919

1926 1 M.

1938

M.

1948

G.

N.

M.

G.

N.

G.

I

Ingrow th (under 0.6 in.)..

117
118
119

348
460
578
543

120

482

A vera g e...............................................

W
Cn

A dvance grow th (spruce, 1 to 12 in. ; balsam,
1 to 8 in. ; birch, 1 to 8 in .)

117
118
119
120

A verage..

U ndesirables (spruce, 13 in. p lu s ; balsam, 9
in. plus ; birch, 9 in. plus)

117
118
119

188

657

43
45
60
28

180
235
130

3.5
3.8
5.0
2.3

3.5
3.8
5.0
2.3

4.5
I 13.5
I 17.5
10.3

4.5
13.5
17.5
10.3

44

158

3.7

3.7

11.5

11.5

3,033
2,718
2,223
3,150

37.5
30.8
19.0
42.5

84.8
78.0
64.3
75.0

0.5
4.5
6.5
1.8

85.3
82.5
70.8
76.8

138.3
133.8
108.5
131.5

0.5
6.5
1.3

138.8
141.8
115.0
132.8

4.1

132.1

5.5
11.0
22.0

11.5
4.5
7.2
7.8

9.6

7.8

465
530
465
460

465
530
465
460

448
505
435
448

433
450
410
436

370
230
235
638

633
445
368
935

1,650
1,380
1,138
1,835

480

480

459

432

368

595

1,501

41

2,781

32.5

75.5

3.3

78.8

128.0

18
18
15
18

1,173
930
1,043
1,505

1,228
1,035
[1,130
1,540

860
450
440
710
55
413 I 848 I 110
915
220
748

975
700
810
773

7.8
15.0
12.5
5.0

-3 0 .7 I 37.5
-2 7 .1 I 36.7
34.4
-23.5
-52.0
62.3

9.6
10.9
10.3

—

17

1,163

1,233

513

815

10.1

42.7

9.4

33
35

120

A verage..

+
+
+
+

515
648
818
645

37

37

17

20

833

96

N .= N e t .
M .= M o rta lity betw een ad ja cen t dates.
G .= G ro s s.
S light differences in decim al values betw een this and T able 4 are due t o con verting to per-acre basis and rou n d in g to nearest tenth.
The number o f trees per a cre in 1926 available fo r in g row th w a s : 1 fo o t high to 0.6 inch, 700 to 1,000; under 1 foot, 600 to 2,200.

8.0

11.5
1 .0

— 3.8
— 14.2
—

1.8

P eriod a fte r L o g g in g
Group at Tim e o f L ogg in g

P lot N o.

0 to 7 Y ears
Cu. Ft.

8 to 19 Y ears

20 to 29 Y ears

P e r Cent

Cu. Ft.

P e r Cent

...

;1

O.U
3.8
5.0
2.3

1

3.7

1

4.0

11.5

1

7.6

1

138.8
141.8
115.0
132.8

Cu. Ft.

P e r Cent

A
4 . 0C

O A

13.5
17.5
10.3

8.5
12.5
6.8

1
In g row th .............................................................................................................

CO
OS

A verage..........................................................................................................
A dvance grow th............................................................................................................

117
118
119
120
......
117
118
119
120

A verage..........................................................................................................
Undesirables...................................................................................................................

A verage..........................................................................................................

1

1
117
118
119
120

1

^o. 7<
4.0
5.8
2.6

37.5
30.8
19.0
42.5

82.8
67.3
54.5
89.5

85.3
82.5
70.8
76.8

!

89.2
86.1
81.7
85.9

1

89.7
89.4
82.3
88.0

32.5

76.3

78.8

1

85.8

132.1

1

87.4

7.8
15.0
12.5
5.0

17.2
32.7
45.5
10.5

6.8
9.5
10.8
10.3

1

7.1
9.9
12.5
11.5

11.5
3.3
7.3
7.8

1
1
1
1

2-1
5.2
5.2

10.1

23.7

9.4

I

10.2

7.5

1

5.0

1

i

N um ber o f Trees

N et V olum e (C u. Ft. p er A cre )

V olum e

Species
1919

CO

1926

1938

1948

1919

11

P lot 117
S pruce................................................................................
Balsam ................................................................................

178
278

P lot 118
S pruce.................................................................................
Balsam ................................................................................

190
320

P lot 119
S pruce.................................................................................
Balsam ................................................................................

148
303

P lot 120
S pruce.................................................................................
Balsam ................................................................................

168
288

1
1
j1

1926

1938

1948

1919

1926

1938

1948

1i

i

178
278

165
263

155
258

200
168

336
290

846
809

1,564
1,354

Per Cent
54.3
45.7

Per Cent
53.6
46.4

P er Cent
51.2
48.8

P er Cent
53.6
46.4

190
320

180
305

165
270

108
118

181
253

574
753

1,308
1,300

48.0
52.0

41.7
58.3

43.2
56.8

50.1
49.9

48.8
51.2

1
1

j

1

1
1

148
303

133
290

398
270

118
111

168
288

163
280

158
273

516
117

178
178

1

723
205

i

1

499
596

1,049
1,099

51.4
48.6

59.9
51.1

45.5
54.4

1,313
505

2,176
879

81.5
18.5

77.9
22.1

72.3
27.7

1
!

71.3
28.7

N um ber o f Trees
P art o f Stand

A verage D .B .H . (I n .)

T otal V olum e (C u. F t.)

P eriodic A nnu al Increm ent
(C u. F t. p er A cre per Y e a r)

Gross —
X

Species
1938

M.

1948

1938

250
502

22
32

298
600
15

5.2
3.1
4.8

M.

1948

1938

M.

1948

N et

M.

Gross

1.7
1.0

6.0
3.5
4.4

852
447
18

4
....
....

; 1,669
I
878
]
34

81.7
43.1

0.4

82.1
43.1

1.6

i

4.5

1,317

2,581

126.4

!

0.4

126.8

9.6

24.3

2.7

Per Cent
9.7
9.6

P lot 117
S.
B.
Bi.

Productive..

913

Sub-total..
N on -p rod u ctiv e (n o t rem oved).

S.
B.
Bi.

Sub-total......

i
I

1.6

j
I

1.6

I

45

!

1,129
386

52

1,234

1,515

965

2,552

4,096

154.5

0.4

154.9

2,741
390

99.0

0.1

99.1

5.7

2 0 .6

1 1.2

3,131

119.6

129.2
15.6

11.3

131.4
26.9

12.8
2.8

13.5

158.3

45
7

52

Grand total..

24.3

348

7 1

10.7
16.2

11.7
16.6

886

1.1

28.1
j

6.1

P lot 291
Productive..
CO

00

S.
B.
Bi.

S.
B.
Bi.

I
I

14
16 I

I
492

Sub-total.................. .
N on-productive (rem oved ).

216
276

30

234
396

I

.....

I

630

1

1.3
1.0

I

- -

5.1

I

1.1

8.2

3.0

36
6

5.. B.. Bi.
5., B., Bi.

536

30

630

930
60

95

I 1,962
I
52

5.. B .. Bi.
5.. B., Bi.

70

1,088

1

!

20.6

1,418
3,353

3.4

2 .0

4.2

1 0 .6

10.1

11.8

Grand total....................
P lot 292
Productive...............................
N on-productive (rem oved) ..

'

1,099
235

1 2.8

Grand total..

1,751
184
1,935

14.0
12.3
15.0

2

Sub-total.......

P lot 118
P rodu ctive......................................
N on-productive (n ot rem oved)..

7.0
2.9

3.6
10.9

1.5

4.3

1,051
1,085

22
113

2,343
1,241

2.136

135

3,584

1,354
1,378

2,670

131.6

M .= M o rta lity between adjacent dates.
X = l n i t i a l volum e o f surviving g row in g stock nineteen to tw enty-nine years follow in g lo g g in g : i.e., volum e 1938 minus m ortality 1938-48.

2 .2

0.9

I

132.5

I

7.9

9.9

T a b l e 7.— D e v e l o p m e n t o f C u t - o v e r P l o t s 1 4 8 t o 1 5 0 b y R e s i d u a l G r o u p s ( p e r A c r e )

N um ber o f Trees
P lot

Group at Tim e o f L ogg in g

P eriodic A nnu al Increm ent
(Cu. F t.)
T otal V olum e (Cu. F t.)
192634

N o.

Ingrow th (under 0.6 i n .)......................................

148
149
150

A dvance grow th (spruce, 1 to 12 in. ; bal­
sam, 1 to 8 in.)

148
149
150

U ndesirables (spruce, over 13 in .;
over 9 in.)

A verage D .B .H . (Sq. F t.)

balsam,

148
149
150

1
1
!
1926 I 1934 1 M. '1 1948
1
1
1
1
1
1 275* [
23
5
88
[ 925*
70
218
775*
30
78
........ 11
1
1
[ 260 { 260
3
258
288 1 288
15
273
293 [ 293
38 j1 255
1
1
1
1
[
25 1
25
3
23
[
43 1
8
35
43
3
8
1
40

!

♦ N um ber o f trees under 0.6 inch available fo r ingrow th in 1934.
M. = M ortality between ad ja cen t dates.
M ortality 1926-34 unknown : hence grow th is gross fo r period 1926-34.

1926

4.6
4.4
4.5
10.7
13.6
16.9

i
i
i 1934 1 M. ! 1948
I
i1
1
1
11
1.0
1.0
1.8
1.0
2.0
1.0
1.6
1
1
1
1
5.9
1.0
8.7
5.3
1.0
7.8
5.5
5.0 j1 8.0
1
1
1
1
11.9 1 16.0 1 14.3
14.3
15.1 ^ 15.9
18.5
20.0 !1 21.0
I

A rea logged in 1926.

1

11

1
1926 1 1934
1

M.

'I 1948
1

1934-48

Gross

11
35
14

N et

1
1
1

M.

Gross

i
1
0.8 1 ..„
2.5 1 ............
1.0

0.8
2.5
1.0

1
1

594
1,109
658
1,069
709 1 1,085
1
1
494
654 ,
1,458
1,627
576
709 j1

131

2,877
2,473
2,411

64.4
50.1
47.0

126.3
100.3
94.7

9.4

126.3
100.3
104.1

119
327
206

823
1,548
680

20.0
21.1
16.6

12.1
— 5.6
— 2.1

8.5
23.4
15.7

20.6
17.8
13.6

P eriodic A nnu al Increm ent
(Cu. F t.)

1

1
Ingrow th (under 0.6 i n .)......................................

192634

Plot
N o.
1927

1934 1
1

M.

1

1948

113
1,028

1927 1 1934
1
!
1
........ 1

45
50

113*
1.028*

58
473

10

A dvance grow th (spruce, 1 to 12 in. ; bal­
sam, 1 to 8 i n . ; birch. 1 to 8 in.)

45
50

620
363

620
363

40
8

580
355

3.2 I
2.5 I

U ndesirables (spruce, 13 in. plus ; balsam.
9 in. plus ; birch, 9 in. plus)

45
50

53 1
10 1

53

25
5

28
5

1
13.6 I
12.9 [

o

T otal Volume (Uu. f t.)

A verage D.B.H . (In .)

N um ber o f Trees
Group at Tim e o f L ogg in g

............

1
1

M.

1

1I 1948
1

1

1

1

1

1927 1 1934 ,1
1

1

1.0
1.3

1.0

3.2 1
3.2 1

1-7
2.4

I
* Ingrow th 1927 to 1948.
M. = M ortality between ad ja cen t dates.

1948

21
1
I

5.8
5.2

554 {
143

930
298

16
........ 11 373
1
6
2,575
3
1,077

1

10

1

N et

Gross

M.

Gross

1
1

1.9
2.4
1

1
1

M.

1934-48

15.2
15.9 1 14.5
13.1 [ 14.6 I 12.0
1
j
1

2,134 1 2,287 1 1,174
149
235 1 243

1.319
102

i
1-2
3.0 1 25.1
1

1.2
25.1

53.8 1 117.5
22.2
55.7
I
1
21.8 1— 69.1
1.2 1— 10.1

118.0
0.5
0.3 1 56.0

1

1
14.7
0.6

83.8
10.7

i

Mortality,
1933-38

1933

99
348
9.1
5,559
4,614
56.2

A ge ......................................................................
N um ber o f trees*...........................................
A verage D .B .H .............................................
Total volume, cu. ft. (1 in. p lu s )...............
M erchantable volume, cu. ft. (7 in. plus)
M .A.I. total, cu. f t ..........................................

1938

23
6.5
171
110

I

M ortality,
1938-48

104
328
9.6
5,885
4,989
56.6

1948

114
318

43
7.8

1 0.0

6,451
5.502
56.6

* Includes ingrow th.

Periodic Annual Increm ents (Total Cubic F e e t)
Plot No.

Period

N et

M ortality

228.................................................................................
228.................................... -........................-..................

1933-38
1938-48

65.2
56.6

34.2
48.8

Gross
1

[
1

1

•
95.4
105.4

i

Compare with
102-116 (u n even -a ged )...........................................

1938-48

I

22.7

1

68.7

1

v ic t o r ia .

B .(\ :

P r i n t e d liy D o n M c D i a r m i d , P r i n t e r t o t h e K i n g ’ s M o s t E x c e l l e n t M a j e s t y .

11)19.

91.4 ±

5.1