J u l y 1960
S t a t i o n P a p e r No. 51
Decay of Subalpine 3 i r in Colorado
This file was created by scanning the printed publication.
Errors identified by the software have been corrected;
however, some errors may remain.
T h o m a s E. H i n d s , F r a n k G. H a w k s w o r t h , a n d R o s s W. D a v i d s o n
Plant Pathologists
R O C K Y MOUNTAIN F O R E S T AND R A N G E E X P E R I M E N T S T A T I O N
Raymond P r i c e , Director
FOREST SERVICE
F o r t Collins, Colorado
U.
S.
DEPARTMENT O F AGRICULTURE
DECAY
O F
SUBALPINE
FIR
IN
COLORADO
T h o m a s E. H i n d s , F r a n k G. H a w k s w o r t h , and R o s s W. Davidson
Plant Pathologists
R o c k y Mountain F o r e s t and R a n g e E x p e r i m e n t S t a t i o n -1 /
C O N T E N T S
Page
. . . . . . . . . . . . . .
1
. . . . . . . . . . .
1
. . . . . . . . . . . . . . .
2
Intensive study
. . . . . . . . . . . .
2
Extensive study
. . . . . . . . . . . .
3
. . . . . . . . . . . . . . .
3
Introduction
R e v i e w of l i t e r a t u r e
Methods
Results
D e c a y i n r e l a t i o n to a g e , t r e e d i a m e t e r , and s i t e
D e c a y fungi
. . . . . . . . . . . . .
E n t r a n c e points and e x t e r n a l i n d i c a t o r s of d e c a y
Summary
3
8
12
. . . . . . . . . . . . . . .
12
. . . . . . . . . . . .
13
Literature cited
1 / F o r e s t S e r v i c e , U. S. D e p a r t m e n t of A g r i c u l t u r e ,
with c e n t r a l h e a d q u a r t e r s i n c o o p e r a t i o n with C o l o r a d o S t a t e
U n i v e r s i t y a t F o r t C o l l i n s . R o s s W. Davidson i s now s t a t i o n e d
at the F o r e s t D i s e a s e L a b o r a t o r y , B e l t s v i l l e , M a r y l a n d .
DECAY
O F SUBALPINE FIR
IN
COLORADO
by
Thomas E. Hinds, F r a n k G. Hawksworth, and R o s s W. Davidson
INTRODUCTION
Spruce-fir i s one of the m a j o r f o r e s t types
in the c e n t r a l Rocky Moun.tains. Engelmann spruce, P i c e a engelmanni P a r r y , i s usually the predominant
species with subalpine f i r , Abies l a s i o c a r p a (Hook. ) Nutt., making up one-fourth
o r l e s s of the total volume. Lodgepole pine, Pinus contorta Dougl. ex Loud. ,
i s frequently present a t the lower elevations of the s p r u c e - f i r type.
The objectives of this study were to obtain preliminary information on the
r o t s of subalpine fir and to r e l a t e decay with age and site conditions. M o r m a tion was a l s o d e s i r e d on entrance points for r o t fungi, the identification of these
fungi, and external indicators of decay.
Most spruce -fir stands a r e m a t u r e to o v e r m a t u r e ( L e B a r r o n and Jemison,
1953). Cutting h a s been relatively limited in the type because of inaccessibility
and s e v e r e climate. However, the r a t e of harvesting i s increasing.
In the c e n t r a l Rocky Mountains the s p r u c e -fir type r e a c h e s i t s maximum
development in western Colorado between 9,000 and 11,000 feet, but the type
extends f r o m 8, 000 to 11, 500 f e e t (Alexander, 1958).
The species composition in spruce-fir f o r e s t s varies. In the plots studied,
the approximate proportion of b a s a l a r e a in t r e e s l a r g e r than 10 inches in diarne t e r was 75 percent spruce, 20 percent f i r , and 5 percent lodgepole pine. The
proportion of fir ranged f r o m z e r o to 33 percent.
REVIEW
O F LITERATURE
A review of a l l studies of decay of North American t r u e f i r s was m a d e by
Basham, Mook, and Davidson (1953).
Very little has been published on decay in subalpine f i r . The only c o m p r e hensive study of this species i s that by B i e r , Salisbury, and Waldie (1948) f o r the
Upper F r a s e r region of B r i t i s h Columbia. This study demonstrated a consistent
relationship between age and decay. Decay was present, but not s e r i o u s , in t r e e s
l e s s than 80 y e a r s old. A pathological rotation of 121 to 140 y e a r s was suggested
on the b a s i s of the maximum net periodic increment. Twenty-one decay fungi
w e r e isolated, but S t e r e u m sanguinolentum ( F r . ) F r . and Echinodontium tinctorium
E. and E. were responsible for 87 percent of the total decay. S t e r e u m sanguinolenturn alone accounted for 47 percent of the decay.
F o s t e r (1954) presented further data based on the study by Bier, Salisbury,
and Waldie (1948). He found that alpine f i r s having forked s t e m s o r bearing
sporophores w e r e complete culls. Twenty-six percent of the cull t r e e s were
in these two c l a s s e s . It was suggested that site quality and a l s o age and s i z e
of the associated species may influence decay in subalpine f i r , but no quantitative data were given.
Information on defect in mature and overmature subalpine fir, lodgepole
pine, and Engelmann spruce in Colorado was presented by Hornibrook (1950).
F o r a l l species, 87 percent of the defect was due to decay. Hornibrook indicated that Fomes &i
( F r ) Kar st. and Ster eum sanguinolentum were the pr i
m a r y decay fungi in subalpine f i r , but he did not compare their relative importance. Other decay fungi found in this species were Coniophora cerebella P e r s .
(occasional), Polyporus tomentosus F r . var. circinatus ( F r . ) Sartory & Maire
( r a r e ) , and A r m i l l a r i a mellea ( F r . )Quel. ( r a r e ) . Mechanical s c a r s in subalpine
f i r were frequently associated with decay. Other indicators of decay were discussed f o r all t h r e e t r e e s (fir, pine, and spruce) a s a whole and their significance f o r each species was not recorded.
.
-
Thomas (1958) recognizes 17 ecological habitats in which subalpine f i r
o c c u r s in British Columbia. The t r e e was attacked by the h e a r t - r o t fungus,
Echinodontium tinctorium, in a l l but one of these habitats. However, the
abundance of the fungus varied considerably in the different habitats. More
than 25 percent of the t r e e s bore sporophores in only two habitats. The fact
that many subalpine f i r s w e r e not infected was thought to indicate a degree of
natural resistance.
Guides for timber stand improvement operations in the spruce-fir type
in the central Rocky Mountains a r e given by Alexander (1957). Logging s c a r s ,
f i r e s c a r s , f r o s t cracks, sunscald, worm o r carpenter ant holes, and s p o r o phores were listed a s external indicators of decay in subalpine fir.
METHODS
The present study was conducted in two general parts. The first, the
intensive study, involved dissection of a l l subalpine f i r in selected sample
plots. In the second part, the extensive study, information was obtained on
decay in subalpine f i r s felled in commercial logging operations.
In southern Colorado, corkbark fir, Abies lasiocarpa var. arizonica
(Merr. ) Lemm., i s common. No attempt was made to separate this variety
lasiocarpa var. lasiocarpa) in these studies.
f r o m typical subalpine f i r
(A.
INTENSIVE STUDY
Sample plots f r o m 114 to 112 a c r e were selected in spruce-fir stands.
All subalpine f i r s , 6.0 inches in diameter o r l a r g e r , were felled and dissected
into 8-foot lengths t o a top diameter of 4.0 inches. If decay was found, the
bolts were further dissected o r split open to m e a s u r e the extent of decay.
The total height, diameter a t b r e a s t height, age a t stump height (1 foot), and
dominance c l a s s were recorded for each tree. Notes of decay were made and
isolations attempted whenever the causal fungus was questionable.
Cubic-foot volumes for each 8-foot bole were determined by use of
Smalian' s formula
A t a
2
x R
when
A = a r e a of top c r o s s section
a = a r e a of bottom c r o s s section
f = l e n g t h i n feet
This same formula was used to calculate cubic foot decay volume if the r o t
extended through the bolt. If decay was present on any one end of the bolt,
the r o t volume was calculated a s a cone. Board-foot volumes were d e t e r mined by plotting the t r e e s on c a r d s and marking off 16-foot logs. A 3-inch
trimming allowance was made. A top diameter of 7.6 inches was used. The
top log was the l a r g e s t even-foot length possible between 8 and 16 feet. Board
foot decay was calculated by using the basic deduction formula
when
A and B = cross-section dimensions (in inches) of the decay
column. One inch i s added to each dimension a s a
safety factor
= length of the decay column (in feet)
1
EXTENSIVE STUDY
In the extensive study, plots of about 1 a c r e were s e t up in spruce-fir
sale a r e a s just before cutting. All t r e e s l a r g e r than 9. 6 inches in diameter
were tagged. The d.b.h., crown c l a s s , and abnormalities that might indicate
decay were recorded for each t r e e . The t r e e s were then felled by loggers and
bucked into 16-foot o r s m a l l e r logs, a s i s usual in local practice. The total
height was then m e a s u r e d to the c l o s e s t 1 foot. As many m e a s u r e m e n t s a s
possible were made of diameter inside b a r k and r o t d i a m e t e r s a t various
points up the tree. The t r e e s were then reconstructed on c a r d s and the
cubic foot g r o s s and decay volumes calculated a s in the intensive study.
Board foot g r o s s and decay volumes w e r e m e a s u r e d directly f r o m the logs.
RESULTS
A s u m m a r y of the basic plot data for the ten intensive and six extensive
plots i s given in table 1. Only the 277 t r e e s , 9.6 inches d. b. h. o r l a r g e r , a r e
included in this table. An additional 42 t r e e s between 7 . 6 and 9.5 inches in
diameter were m e a s u r e d in the intensive study. The location of the 16 study
a r e a s i s shown in figure 1. Data f r o m the intensive and the extensive plots
were combined for the following analyses. The plots cut in 1959 had about
one -third m o r e decay (41 percent, board foot b a s i s ) than the plots cut e a r l i e r
(30 percent). However, i t i s not possible to compare the two s e t s of data
directly, since stand ages were not obtained f o r three of the 1959 plots. The
1959 measurements were obtained f r o m logs cut in the woods, hence these
a r e probably m o r e representative of cull percentages for c o m m e r c i a l o p e r a tions under c u r r e n t utilization standards.
DECAY IN RELATION TO AGE,
TREE DIAMETER, AND SITE
The average proportion of decay for a l l t r e e s l a r g e r than 9.5 inches in
diameter was 35 percent on a board foot b a s i s and 9.9 percent in cubic feet.
-
A general, but poorly defined, i n c r e a s e in volume of decay with i n c r e a s
ing age i s apparent f r o m plot averages (fig. 2). The differences between plots
were very marked. F o r example, plot L (Grand Mesa-Uncompahgre National
F o r e s t ) with an average stand age of 153 y e a r s showed 33 percent decay, while
on plot F (White River National F o r e s t ) where the t r e e s were nearly 80 y e a r s
older, the decay amounted to only 18 percent.
Table 1. --Summary of b a s i c plot d a t a f r o m the subalpine f i r decay study
b a s e d on t r e e s over 9.5 inches in d i a m e t e r
.
.
PlotNo.
: Board foot b a s i s : Cubic foot b a s i s
T r e e :Average: Site
and
Gross
Gross :
:basis
age :index1 '
Decay:
Decay
national f o r e s t :
: volume :
volume :
No.
Years
Bd. ft.
Pct.
Cu. ft.
Pct.
-
:
.
.
-
-
INTENSIVE STUDY (1953-54)
.........................
Minus
Plus
Minus
Minus
Plus
Minus
Plus
Plus
Minus
Minus
E
C
G
A
B
H
J
White R i v e r
Rio Grande
Routt
Rio Grande
Rio Grande
Routt
San Juan
F White R i v e r
D White R i v e r
I Routt
All intensive plots
L Grand MesaUncompahgr e
P Routt
N Roosevelt
K Roosevelt
M Grand M e s a Uncompahgre
0 Routt
--
28, 130
EXTENSIVE STUDY
-----------------20
28
13
6
(2/)
29
7
(
(
All e x t e n sive plots 103
All plots
--
174
277
153
215
320
'/ )
21)
30
6,214.1
9.2
(1959)
Plus
Plus
Plus
Minus
4,990
6, 110
1, 660
410
33
45
34
10
999.2
1,222.9
384.4
96.7
12.6
11.7
7.7
3.9
Plus
plus
4,320
77 0
55
23
784.8
172.9
12.2
5.2
--
--
18, 260
41
3,660.9
11.1
--
--
46, 390
35
9,875.0
9.9
'
B a s e d on height-age relationship of a s s o c i a t e d Engelmann s p r u c e
(Hornibrook, 1942). P l u s s i t e s , s i t e s 8 0 o r b e t t e r ; m i n u s s i t e s , s i t e s 70 o r
poorer.
'sample insufficient to obtain a r e l i a b l e e s t i m a t e of stand age.
When t r e e s on a l l plots w e r e s o r t e d into age c l a s s e s , i t appeared that
d e c a y b o r e a cyclic relation to age (fig. 3). P e r c e n t d e c a y was negligible in
the few t r e e s younger than 100 y e a r s , but i n c r e a s e d rapidly with increasing age
to 35 p e r c e n t (board-foot b a s i s ) in the 150-199 y e a r age c l a s s . P e r c e n t decay
found then d e c r e a s e d with i n c r e a s i n g age through the 200-249 and 250-299 y e a r
age c l a s s e s . Only 18 p e r c e n t of the board-foot volume of the l a t t e r c l a s s was
decayed. The p e r c e n t of decay found then i n c r e a s e d again with i n c r e a s i n g age
in stands older than 300 y e a r s . Nearly 60 p e r c e n t of the g r o s s volume of the
seven t r e e s in t h e 350-399 y e a r age c l a s s was decayed.
LEGEND
MCADOUAITCII
F i g u r e 1. --Map of Colorado showing the location of
subalpine f i r decay study plots.
50
0
>
a
:
PLUS
28
SITES
0 O
MINUS SITES
20
I,*
40
0
I-
20
0
0
2
22
------------03
34
STAND AGE
(YEARS)
Figure 2. - - P e r c e n t decay in relation to a v e r a g e stand age in 16 subalpine f i r
plots. The t r e e b a s i s f o r each plot i s indicated by the figures.
Figure 3.
--
Proportion of board-foot
and cubic -foot decay by
50-year age c l a s s e s .
P e r c e n t decay i s indicated by the figure on
0
50
I00
I50
200
250
300
350
400)
top of each b a r and the
AGE ( Y E A R S )
t r e e b a s i s f o r the age
I
CUBIC F E E T
c l a s s i s shown by the
lower figure in each b a r .
The proportion of butt
and trunk r o t s in each
age c l a s s i s a l s o shown.
Total b a s i s : 169 t r e e s .
0
50
100
I50
200
250
AGE ( Y E A R S )
300
350
I
loo
The apparent cyclic relationship between age and decay in subalpine f i r
i s s i m i l a r to that r e p o r t e d by Boyce and Wagg (1953) for -F o m e s pini in Douglasf i r in Oregon. At l e a s t two f a c t o r s m a y be involved in t h i s relationship in subalpine f i r : (1) some of the t r e e s infected with decay e a r l y in life a r e killed
directly by p a r a s i t i s m of the decay fungi o r indirectly by windthrow o r wind
breakage, and (2) growth of the remaining t r e e s i s enhanced by the r e l e a s e
due to the l o s s of the m o r e decadent t r e e s . It s e e m s likely that butt r o t s a r e
a p r i m a r y r e a s o n f o r death of infected t r e e s . Butt r o t s accounted for n e a r l y
60 percent of the decay b o a r d - f o o t b a s i s ) in stands l e s s than 250 y e a r s old.
The proportion of t r e e s with butt and top r o t s i s shown in table 2. This a l s o
points out the high incidence of butt r o t s in stands younger than 250 y e a r s .
T h e r e was a m a r k e d relationship between percent decay and t r e e d i a m e t e r (fig. 4). Decay b o a r d - f o o t b a s i s ) ranged f r o m l e s s than 7 percent in
t r e e s under 10 inches d. b.h. to m o r e than 40 percent f o r t r e e s over 20 inches
in diameter.
Table 2. - - T r e e s with butt and trunk r o t s by 50-year age c l a s s e s
Age Class :
T basis:
~
IYP~Ts\ :
:
Nurnbe r
~
~Proportion of t r e e s with-Butt r o t
: Trunk r o t :
All r o t s
Percent - - -
---
Figure 4.
--
40
Decay in relation
---BOARD
FEET (291 TREES)
C U B I C F E E T ( 3 1 9 TREES)
34
-
I
,'
t
a
t r e e b a s i s for
each point i s
indicated by
the figure.
The
$
0
I'
I
3 0 -
'\
20
-
10
-
K
W
a
\
I
\
x
I
I1
\
= 3,4
z
W
;
Y-4s
0
to diameter.
>' 9
P'
I
\
I
Y
43
I
I
23
0
2
4
6
8
10 12
14 16
18 2 0 2 2 2 4 2 6
DIAMETER BREAST HEIGHT
There was no consistent relationship between site c l a s s and prevalence
of decay (see fig. 2). Also, the following tabulation shows that decay on the
two sites was similar. ( F o r this analysis, plot E, in which only three t r e e s
were cut, was excluded. )
Site c l a s s
(based on associated Engelmann
spruce -Hornibrook, 1942)
-
Average age of t r e e s ( y e a r s )
Decay (percent) :
Board-foot b a s i s
Cubic -foot b a s i s
Basis:
Plots (number)
T r e e s (number)
80 o r better
70 or poorer
213
21 1
DECAY FUNGI
Identifications of fungi were made for 58 percent of the decay infections
and these accounted for about the s a m e proportion of the total decay volume.
F o r a l l t r e e s , butt r o t s accounted for about one-third of the total decay volume
and trunk r o t s for two-thirds. Identified decays accounted f o r 7 4 percent of
the total trunk r o t volume, but only 17 percent of the butt r o t volume was
associated with identified decays.
Eighteen r o t fungi w e r e identified (table 3). Some of the fungi listed
r e q u i r e f u r t h e r study for positive identification. At l e a s t two additional butt
r o t fungi were isolated (one isolated eight t i m e s and the other five t i m e s ) but
these cannot yet be identified f r o m their cultural c h a r a c t e r i s t i c s . Six fungi
were a s s o c i a t e d with trunk decay and 12 associated with butt r o t s w e r e identified. Relatively few of the butt r o t fungi were isolated. Also, in many instances,
two o r m o r e infections were found in the s a m e p a r t of the butt, s o it was difficult
to a s s i g n a n a c c u r a t e volume of decay to a particular fungus.
Table 3. --Fungi associated with 164 identified decay infections in subalpine fir
in Colorado (intensive and extensive studies)
Fungus
:
Type
: ofrot
: Infections
:
No.
Pct.
-
-
j ~ e c volume
a ~
Cu. ft.-Pct.
Trunk r o t s :
.
Stereum sanguinolentum (Fr ) F r
Fome s p i n 1 ( F r ) Kar st.
S t e r e u m chailletii ( F r . ) F r .
Stereum abietinurn ( F r . ) Fr.
F o m e s robustus Karst. var.
tsugina (Murr. ) Overh.
Rom.
Peniophora
.
.
3
White
White
White
Brown
White
61
12
11
4
3
66.3
13. 0
12.0
4.3
3.3
418.5
82.8
28. 0
7.5
7.5
Brown
1
1.1
0
92
100.0
Total trunk r o t s
544.3
Butt r o t s :
Corticium radiosum (Fr. ) F r .
Coniophora ~ D D 1.
A r m i l l a r i a mellea ( F r ) Quel.
Pholiota s q u a r r o s a (Fr. ) Kummer
Coniophora olivacea ( F r . ) Karst.
Polyporus tomentosus F r var
c i r c i n a t u s ( F r . ) S a r t o r y & Maire
Pholiota alnicola ( F r . ) Singer
Helicobasidium corticioides Bandoni
Polyporus balsameus Pk.
F o m e s nigrolimitatus (Rom. ) Egel.
Stereum sulcatum B u r t
Coniophora a r i d a ( F r . ) Karst.
L
A
.
.
Total butt r o t s
.
White
Brown
White
White
Brown
White
Trace
9. 6
8.5
8.5
6.5
5.7
White
Brown
Brown
White
White
Brown
1.8
1.5
5.8
6.0
Trace
Trace
72
2.
100.0
53.9
100.0
'Probably mostly
puteana ( F r . ) Karst. a s this species i s common on
subalpine f i r but specific determinations were not made.
Stereum sanguinolentum was by f a r the m o s t important decay fungus in
subalpine f i r (fig. 5C, 5D). It accounted for two-thirds of the identified trunk
F o m e s pini was the
r o t infections and 77 percent of the trunk r o t volume. -next m o s t important trunk r o t fungus and accounted for about 15 percent of
the identified trunk r o t volume. Other trunk r o t fungi isolated were Stereum
chailletii, S. abietinum, Peniophora luna, and F o m e s robustus var. tsugina
(fig. 5A). The l a t t e r fungus i s parasitic. Although i t w a s isolated f r o m only
t h r e e living t r e e s , i t was found fruiting on s e v e r a l f i r s broken off n e a r the
ground level. These t r e e s were mostly l e s s than 10 inches in d i a m e t e r ; this
suggests
that some of the e a r l y mortality in subalpine f i r stands may be due
-to F. robustus var. tsugina.
-
Corticium radiosum, a white r o t fungus which was recently reported
f r o m living t r e e s f o r the f i r s t time (Davidson and Hinds, 1958), was the m o s t
frequently isolated butt r o t fungus, b u t i t produced only negligible amounts of
decay.
Twenty-one infections were associated with Coniophora spp. These cause
brown cubical butt r o t s . Two species, C. olivacea (eight infections) and C.
- -a r i d a
(one infection), were determined. It s e e m s likely that m o s t of the remaining
isolates were of C. puteana although specific determinations were not made.
-
A r m i l l a r i a mellea was isolated 11 t i m e s . However, it i s likely that
this fungus i s m o r e common, for many isolations of decay that appeared to
be caused by A.
mellea w e r e either unsuccessful o r yielded only contaminants.
- Other white r o t fungi isolated f r o m butt decays were Pholiota s q u a r r o s a ,
P.
alnicola,
Polyporus tomentosus var. circinatus, Stereum sulcatum, and
F o m e s nigrolimitatus (fig. 5B). In addition, two fungi causing brown cubical
butt r o t s w e r e identified: P o l v ~ o r u sb a l s a m e u s and Helicobasidium corticioides.
The l a t t e r fungus was described recently f r o m decay in Rocky Mountain
subalpine f i r (Davidson and Hinds, 1958).
,A
The decay fungi
- associated with subalpine f i r in Colorado w e r e very diff e r e n t f r o m those reported for f i r --subalpine and s i l v e r f i r s (Abies a m a b i l i s
(Dougl. ) F o r b e s ) combined- - i n the upper F r a s e r region of B r i t i s h Columbia
(Bier, Salisbury, and Waldie, 1948). The main difference was the absence of
the Indian paint fungus, Echinodontium tinctorium, in subalpine f i r in Colorado.
I n B r i t i s h Columbia, E. tinctorium caused n e a r l y a s much decay a s S t e r e u m
sanguinolentum. E . c n c t o r i u m i s , however, common on white f i r (Abies
concolor (Gord. c lend. ) Lindl. ) in Colorado.
None of the h e a r t r o t fungi in Colorado subalpine f i r consistently f o r m
fruiting bodies, s o there a r e no positive external indicators of infection.
The brown stringy r o t caused by Stereum sanguinolentum, the brown
cubical r o t s of Coniophora spp., and the white pocket r o t s caused by F o m e s
pini and F. nigrolimitatus a r e distinct enough s o that they can be f a i r l y r e l i ably diagIosed f r o m the appearance of the decay alone. However, even f o r
these, c e r t a i n infections could not have been identified without cultures.
-
Butt r o t s accounted for about one-third of the total decay, and these a r e
thought to be of m a j o r significance in the history of subalpine f i r stands because
they lead to windthrow. Little i s known of the extent of p a r a s i t i s m by root and
butt r o t fungi in subalpine fir o r other Rocky Mountain conifers. This i s an
important field for future investigations.
Figure 5. --Decays in subalpine
fir.
(Inch scale shown in each
photograph. )
A.
-
Cross section showing
decay caused by Fomes
robustus var. tsugina
that has invaded the sapwood and killed the
cambium.
I
I
'1
..
d
\
',!.J
*J
, ;3
-B,
White pocket rot caused by
Fomes nigrolimitatus.
C,
-
Trunk decay caused by
Stereurn sanguinolentum.
D,
-
Incipient stage of S. sanguinolenturn decay concentrated back
of a dead branch stub.
ENTRANCE POINTS AND EXTERNAL INDICATORS O F DECAY
F o r m o s t subalpine f i r s t h e r e w e r e no positive e x t e r n a l indicators of
decay. It h a s been previously mentioned that none of the h e a r t - r o t t i n g fungi
consistently f o r m fruiting bodies on living f i r s . One r e a s o n for the l a c k of
e x t e r n a l i n d i c a t o r s was that m o r e than half of the decay infections apparently
e n t e r e d through the r o o t s .
The a p p a r e n t e n t r a n c e points f o r 322 decay infections a r e a s follows:
Entrance ~ o i n t
Infections
(Percent)
Roots
Basal wounds
Trunk wounds
B r a n c h stubs
Broken tops
Frost cracks
Dead l e a d e r
Forks
Broken tops and trunk wounds w e r e usually indicative of extensive decay.
S t e r e u m sanguinolentum decay was frequently a s s o c i a t e d with broken tops.
However, this fungus a l s o e n t e r e d through b r a n c h stubs.
SUMMARY
Information on decay in subalpine f i r was obtained by dissecting 319 t r e e s
in 16 plote in Colorado. Decay for a l l t r e e s l a r g e r than 9. 5 inches d. b. h. w a s
35 p e r c e n t on a board-foot b a s i s and 9.9 p e r c e n t for cubic feet. T h e r e was an
i r r e g u l a r relationship between decay and age. Decay i n c r e a s e d with age to a
peak in the 150-200 y e a r age c l a s s , then declined with age to a m i n i m u m in the
250-300 y e a r age c l a s s , and then i n c r e a s e d again with advancing age to a second
peak in the 350-400 y e a r age c l a s s .
The decline in decay in t r e e s a f t e r 200 y e a r s m a y be due to the death
(possibly through wind b r e a k a g e o r windthrow) of the m o r e decadent t r e e s .
T h e r e was no apparent r e l a t i o n s h i p between d e c a y and s i t e quality.
The fungi a s s o c i a t e d with about 58 p e r c e n t of the decay volume w e r e
identified. S t e r e u m sanguinolent um was by f a r the m o s t important decay
fungus, followed by -F o m e s p h i . In all, 18 fungi w e r e isolated--6 f r o m t r u n k
d e c a y s and 12 f r o m butt r o t s .
None of the d e c a y fungi consistently f r u i t on living t r e e s , and t h e r e a r e
no consistent e x t e r n a l indicator8 of decay. However, broken tops and trunk
wounds w e r e usually indicative of extensive decay.
LITERATURE CITED
Alexander, R. R.
1957. P r e l i m i n a r y guide to stand improvement in cutover stands of s p r u c e
fir. U. S. F o r e s t Serv. Rocky Mountain F o r e s t and Range Expt
Sta. R e s . Note 26, 6 pp. [ P r o c e s s e d . ]
.
1958.
-
Silvical c h a r a c t e r i s t i c s of subalpine f i r . U. S. F o r e s t Serv. Rocky
Mountain F o r e s t and Range Expt. Sta. Sta. P a p e r 32, 15 pp., illus.
[ Processed. ]
Basham, J. T . , Mook, P. V., and Davidson, A. G.
1953. New information concerning b a l s a m f i r d e c a y s in e a s t e r n North
America. Canad. Jour. Bot. 31: 334-360, illus.
B i e r , J. E . , Salisbury, P. J., and Waldie, R. A.
1948. Studies in f o r e s t pathology V. Decay in f i r , Abies l a s i o c a r p a and
A. a m a b i l i s , in the upper F r a s e r region of B r i t i s h Columbia.
Canada Dept. Agr. Tech. Bul. 66, 28 pp., illus.
Boyce, John S., and Wagg, J. W. Bruce.
1953. Conk r o t of old-growth Douglas-fir in w e s t e r n Oregon.
Prod. Lab. Bul. 4, 96 pp., illus.
Oreg. F o r e s t
Davidson, R o s s W., and Hinds, Thomas E.
1958. Unusual fungi a s s o c i a t e d with d e c a y in some f o r e s t t r e e s in Colorado.
Phytopathology 48: 216-218, illus.
F o s t e r , R. E.
1954. Decay of alpine f i r in the Upper F r a s e r region. Canada
Sci. Serv. F o r e s t Biol. Div., Bimo. Rpt. lO(5): 3.
Hornibrook, E . M.
1942. Yield of cutover s t a n d s of Engelmann s p r u c e .
778-781, illus.
1950.
Dept. Agr.
Jour. F o r e s t r y 40:
E s t i m a t i n g defect in m a t u r e and o v e r m a t u r e stands of t h r e e Rocky
Mountain c o n i f e r s . Jour. F o r e s t r y 48: 408 -417, illus.
L e B a r r o n , R u s s e l l K. , and Jemison, George M.
1953. Ecology and silviculture of the Engelmann s p r u c e -alpine f i r type.
Jour. F o r e s t r y 51 : 349 -355, illus.
Thomas, G. P.
1958. Studies in f o r e s t pathology. XVIII. The o c c u r r e n c e of the Indian
paint fungus, Echinodontium tinctorium E. & E . , in B r i t i s h
Columbia. Canada Dept. Agr. F o r e s t Biol. Div. Pub. 1041,
30 pp., illus.
Agriolltm
--.CSU, R.Collins