REFINEMENT AND QUANTIFICATION OF DATA FOR REGULATING DWARF MISTLETOE
POPULATIONS:AN ECOSYSTEMS APPROACH^
Ed F. Wicker-2/
A b s t r a c t : Some examples o f e x i s t i n g q u a n t i t a t i v e d a t a on
t r e e growth r e d u c t i o n r e s u l t i n g from dwarf m i s t l e t o e i n f e c t i o n s
a r e p r e s e n t e d and evaluated. The need f o r a c c u r a t e and r e l i a b l e
q u a n t i t a t i v e d a t a i s explained. The r o l e o f d i s e a s e s i n t h e
p l a n t ecosystem i s discussed. Application of p r i n c i p l e s and
concepts o f p l a n t ecology t o c o n t r o l dwarf m i s t l e t o e s i n t h e
ecosystem i s advocated.
INTRODUCTION
Dwarf m i s t l e t o e s (Arceuthobium spp.)
cause some o f t h e most important d i s e a s e problems c o n f r o n t i n g managers o f coniferous f o r e s t s
o f western North America. These pathogens a r e
n o t new. They a r e a s much a p a r t o f our American h e r i t a g e a s t h e v a s t c o n i f e r o u s f o r e s t s
themselves. T h e i r e f f e c t s on our f o r e s t r e s o u r c e s a r e viewed a s problems t o management o f
t h e s e r e s o u r c e s because o f t h e demands man has
placed on t h e f o r e s t s f o r goods and s e r v i c e s .
Recent e s t i m a t e s o f timber l o s s e s a t t r i b u t e d t o
dwarf m i s t l e t o e s i n t h e Western United S t a t e s
and Alaska exceed 3.3 b i l l i o n board f e e t
annually
.
Despite t h e prevalence o f dwarf m i s t l e t o e s ,
many b i l l i o n board f e e t o f timber has been harv e s t e d from t h e Western United S t a t e s s i n c e t h e
a r r i v a l o f t h e f i r s t s e t t l e r s . As t h i s country
grows and i t s population i n c r e a s e s , t h e demands
on our f o r e s t land f o r both goods and s e r v i c e s
w i l l i n c r e a s e p r o p o r t i o n a t e l y . Simultaneously,
t h e t o t a l a r e a o f f o r e s t land w i l l decrease,
g i v i n g way t o h i g h e r p r i o r i t y use such a s housi n g , highways, power l i n e rights-of-way, r e s e r v o i r s f o r h y d r o - e l e c t r i c p r o j e c t s , e t c . The
challenge i s written. I f s o c i e t i e s a r e t o
à ‘ l ~ r e s e n t e a t Symposium on Dwarf M i s t l e t o e
Control through F o r e s t Management, Berkeley,
C a l i f . , A p r i l 11-13, 1978.
2/
P r i.n c i p a l P l a n t P a t h o l o g i s t , Intermountain
F o r e s t and Range Experiment S t a t i o n , Forest
S e r v i c e , U.S. Department o f A g r i c u l t u r e ,
Moscow, Idaho.
continue t o enjoy t h e p l e a s u r e s and comforts
of t h e many goods and s e r v i c e s d e r i v e d from
t h e f o r e s t , then we must produce more and
more of t h e s e amenities on a continuously
s h r i n k i n g f o r e s t land base.
While t h e r e a r e s e v e r a l o p t i o n s f o r
meeting t h i s challenge, one of t h e more
v i a b l e a l t e r n a t i v e s i s t o maintain our f o r e s t lands i n a s t a t e o f high p r o d u c t i v i t y .
One of t h e more l o g i c a l s t a r t i n g p o i n t s f o r
improving f o r e s t land p r o d u c t i v i t y i s t o
c a p t u r e t h o s e l o s s e s t o d i s e a s e s such a s
dwarf m i s t l e t o e s . Dwarf m i s t l e t o e s provide
a good example because t h e i r biology i s well
understood and t h e i r populations a r e r e a d i l y
amenable t o management by s e v e r a l s i l v i c u l t u r a l practices.
The importance of dwarf m i s t l e t o e s a s
pathogens i n coniferous f o r e s t s was demons t r a t e d and recorded i n t h e e a r l y p a r t o f
t h e t w e n t i e t h century (Weir 1916a,b). Fore s t e r s have been slow t o r e a l i z e t h e f u l l
e x t e n t of l o s s e s caused by t h e s e p e s t s .
There a r e s e v e r a l reasons f o r t h i s s i t u a t i o n . One i s t h e f a c t t h a t t h e Western
United S t a t e s was b l e s s e d with an abundance
of coniferous f o r e s t s . This i s conspicuously evident today a s a t t e s t e d by some o f
t h e i s s u e s and responses concerning a c c e l e r a t e d c u t t i n g o f t h e "surplus" growing
stock on t h e Federal f o r e s t lands r e p o r t e d
i n "The Resources Planning Act: A Progress
Report" (USDA Forest S e r v i c e 1978). U n t i l
t h i s decade, man has been content t o occupy
h i m s e l f , p r i m a r i l y , with h a r v e s t i n g o f t h e s e
f o r e s t s , deferring t h e i r perpetuation t o t h e
p r e s e n t generation o f mankind.
The second reason we have been slow t o
d e a l e f f e c t i v e l y with dwarf m i s t l e t o e s i s t h e
d e a r t h o f q u a n t i f i e d d a t a t h a t would enable
t h e land manager t o a s s e s s damage, determine
needs f o r c o n t r o l , p r e d i c t growth and y i e l d ,
and c a l c u l a t e c o s t - b e n e f i t r a t i o s of c o n t r o l
o p e r a t i o n s f o r dwarf m i s t l e t o e s . An enormous
knowledge of t h e s e p e s t s i s a v a i l a b l e i n t h e
published l i t e r a t u r e , a s papers a l r e a d y presented a t t h i s Symposium w i l l a t t e s t . Perusal
of t h i s l i t e r a t u r e r e v e a l s t h a t a perponderance
o f t h e information i s documented i n q u a l i t a t i v e
terminology. Furthermore, i t i s v i r t u a l l y
impossible t o transpose t h i s information i n t o
q u a n t i t a t i v e terms because of l i m i t a t i o n s of
time, purpose, and methodology of o r i g i n a l d a t a
c o l l e c t i o n . This d e f i c i e n c y of e f f e c t i v e quant i t a t i v e d a t a i s e s p e c i a l l y conspicuous when
one a t t e m p t s t o u s e systems technology such a s
computers and mathematical models a s a i d s f o r
land management d e c i s i o n s . Let us have a b r i e f
look a t some examples of t h e q u a n t i t a t i v e d a t a
o f dwarf m i s t l e t o e impacts t h a t have been r e ported. You be t h e judge of i t s e f f e c t i v e n e s s
with r e s p e c t t o t o d a y ' s needs.
STATUS OF DWARF MISTLETOE DATA
More than 60 y e a r s ago, J. R. Weir i n v e s t i gated many a s p e c t s o f t h e dwarf m i s t l e t o e s i n
t h e P a c i f i c Northwest. During a period of some
15 y e a r s , he published evidence of t h e prevalence of t h e s e p a r a s i t e s and displayed a recogn i t i o n f o r t h e i r c a p a c i t y t o damage coniferous
f o r e s t s (Weir 1916a,b; 1918). His many r e p o r t s
warned o f t h e d e s t r u c t i v e n a t u r e o f t h e s e pests.
A s e a r l y a s 1916, Weir was recommending s i l v i c u l t u r a l measures f o r c o n t r o l of dwarf m i s t l e t o e s i n t h e n a t i o n a l f o r e s t s of t h e Northwest
(1916~).
Weir (1916a) published one of t h e f i r s t
r e p o r t s of growth impact o f dwarf m i s t l e t o e s
on western l a r c h . Comparing average 10-year
r a d i a l growth o f 29 i n f e c t e d t r e e s with 12
uninfected t r e e s , he reported a 59 percent
reduction i n l i g h t l y i n f e c t e d t r e e s , a 65 perc e n t reduction i n moderately i n f e c t e d t r e e s ,
and a 84 percent reduction i n heavily infected
t r e e s . The p r a c t i c a l s i g n i f i c a n c e o f t h e s e
d a t a i s l o s t because of t h e tremendous age
v a r i a t i o n among sample t r e e s (30 t o 623 years)
and Weir's f a i l u r e t o d e s c r i b e h i s c r i t e r i a
f o r c l a s s i f y i n g d i s e a s e i n t e n s i t y . Another
equally serious limitation of these data w i l l
be r e l a t e d l a t e r i n t h i s paper.
In t h e same y e a r , Weir (1916b) reported
on t h e growth impact of dwarf m i s t l e t o e s i n
lodgepole pine, ponderosa pine, western l a r c h ,
and Douglas-fir.
The growth impact d a t a a r e
summarized i n t a b l e 1 .
Hawksworth and Lusher (1956) reported t h e
growth impact of dwarf m i s t l e t o e on Douglas-fir
i n t h e Southwest. Mortality i n a l l i n f e c t e d
Douglas-fir stands was 4 times g r e a t e r than i n
uninfected stands. Mortality i n i n f e c t e d cutover a r e a s was 4 times g r e a t e r than i n uninfect e d cutover a r e a s and 2 times g r e a t e r than i n
uninfected v i r g i n a r e a s . This l o s s was d i r e c t l y
c o r r e l a t e d with dwarf m i s t l e t o e i n t e n s i t i e s .
Unpublished r e p o r t s by Graham (1956)-31
revealed a 7-, 24-, and 47-percent diameter
growth reduction f o r l i g h t , moderate, and
heavily i n f e c t e d western l a r c h , r e s p e c t i v e l y .
Growth impact d a t a from lodgepole p i n e
stands i n Colorado and Wyoming (Hawksworth 1958)
showed 1.5 times g r e a t e r gross merchantable volume i n uninfected stands a s compared t o i n f e c t e d
stands. Mortality i n v i r g i n stands was 1.3
times g r e a t e r i n dwarf m i s t l e t o e i n f e c t i o n a r e a s
than i n uninfected areas. M o r t a l i t y i n l a r g e
poles was 5 times higher i n i n f e c t e d s t a n d s a s
compared t o dwarf m i s t l e t o e f r e e s t a n d s .
Pierce (1960) studied t h e e f f e c t s of i n f e c t i o n i n t e n s i t i e s on t o t a l height and b a s a l
a r e a i n r e s p e c t t o s i t e , age, and stand dens i t y . Although h i s sampling techniques were
i n h e r e n t l y d e f i c i e n t , h i s r e s u l t s a r e i n gene r a l agreement with those previously reported
A major l i m i t a t i o n common t o a l l t h e s e d a t a
i s t h e absence of a uniform and proven system
f o r describing t h e environmental v a r i a t i o n t h a t
e x i s t e d within and between t h e t e s t d a t a . Weir
(1916a) recognized t h e importance of ecology t o
t h e h o s t - p a r a s i t e r e l a t i o n s h i p . He s t r u g g l e d
t o compare and explain t h e d i f f e r e n c e s i n t h e
ecological amplitudes of Arceuthobium l a r i c i s
(Piper) S t . John and Larix o c c i d e n t a l i s Nutt.
I t was a s t r u g g l e because knowledge of p l a n t
ecological r e l a t i o n s h i p s was not s o advanced a s
it i s today and t h e r e were no proven systems
f o r t h e ecological i d e n t i f i c a t i o n and c l a s s i f i c a t i o n of f o r e s t communities.
THE ECOSYSTEMS CONCEPT AND
THE ROLE OF DISEASES
The individual p l a n t c o n s t i t u t e s t h e b a s i c
component of a p l a n t community. Beginning a s a
sprout, t h e p l a n t i s immediately a f f e c t e d by
t h e a c t i o n s and i n t e r a c t i o n s of t h e many f l u c t u a t i n g b i o t i c and a b i o t i c f a c t o r s of i t s environment. Each of t h e s e f a c t o r s a f f e c t t h e p l a n t
simultaneously. Their i n d i v i d u a l e f f e c t s upon
t h e p l a n t a r e modified and compensated for one
another. The composite of t h e i r a c t i o n s and i n t e r a c t i o n s i s known a s t h e environmental complex.
à ‘ l ~ e c o r don f i l e , Forestry Sciences Laboratory,
Moscow, Idaho.
T a b l e I--Growth r e d u c t i o n o f l o d g e p o l e p i n e , ponderosa p i n e , D o u g l a s - f i r , and w e s t e r n l a r c h c a u s e d
by dwarf m i s t l e t o e s .
Host
No.
trees
Average
age c l a s s
Growth o f i n f e c t e d t r e e s a s p e r c e n t a g e
of t h a t i n uninfected t r e e s
Average
Average
Average t o t a l
height
d.b.h.
a n n u a l growth
Pinus c o n t o r t a
Infected
Uninfected
Pinus ponderosa
Infected
Uninfected
Pseudotsuga m e n z i e s i i
Infected
Uninfected
Larix occidentalis
Infected
Uninfected
Environment i s h i g h l y h e t e r o g e n e o u s , even
more s o t h a n most o f u s can c o n c e i v e . Through
e o n s o f development, l i v i n g systems have exhibi t e d a n expanding p o t e n t i a l t o a d a p t t o e n v i r o n m e n t a l v a r i a b i l i t y and change. P l a n t s a r e no
e x c e p t i o n . T h e i r accumulated f e a t u r e s r e s u l t i n g
from a d a p t a t i o n a r e w e l l documented. Such adapt a t i o n s r e s u l t from i n t e r a c t i o n s between t h e
g e n e t i c c o n s t i t u t i o n o f t h e p l a n t and n a t u r a l
s e l e c t i o n a c t i v i t i e s o f t h e environment. They
may be g e n e t i c a l l y f i x e d o r e n v i r o n m e n t a l l y
induced. While genes may f u n c t i o n a s t e m p l a t e s
f o r morphologic and p h y s i o l o g i c f e a t u r e s o f
l i v i n g s y s t e m s , t h e i r p r o d u c t s a r e s c r e e n e d by
a s e l e c t i v e s i e v e - - t h e environment.
The e c o l o g i c a m p l i t u d e o f p l a n t s i s expans i v e b u t n o t u n l i m i t e d . The p l a n t h a s d e f i n i t e
t o l e r a n c e l i m i t s f o r each f a c t o r o f environment.
When v a r i a t i o n i n any s i n g l e f a c t o r o r combinat i o n o f f a c t o r s exceeds t h e t o l e r a n c e l i m i t s o f
t h e p l a n t , t h e p l a n t w i l l l o s e i t s competitive
p o s i t i o n . I t w i l l be discriminated against
r a t h e r t h a n s e l e c t e d by environment. I t s v i g o r
I f t h i s decline is
and v i t a l i t y w i l l d e c l i n e .
u n a b a t e d , t h e p l a n t w i l l become e x t i n c t i n t h a t
environment. Thus, a s a p l a n t community d e v e l o p s , t h e r e i s a c o n t i n u o u s , g r a d u a l change i n
i t s physiognomy a s a r e s u l t o f t h e r i g o r s o f
e n v i r o n m e n t a l s e l e c t i o n . We s e e t h e r e s u l t i n g
community a s a p r o d u c t o f a m u l t i p l i c i t y o f
i n t e r a c t i o n s encompassing t h e t o t a l h e t e r o g e n e i t y o f environment and e c o l o g i c a m p l i t u d e
o f t h e t a x a r e p r e s e n t e d . The p l a n t community
i n f l u e n c e s t h e environment and t h e environment
i n f l u e n c e s t h e p l a n t community. The two a r e
inseparable.
I consider p l a n t d i s e a s e s a s an i n t e g r a l
p h a s e o f a l l p l a n t ecosystems. They a r e
actively functional factors of t h e natural
s e l e c t i o n p r o c e s s . D i s e a s e s c o n s t a n t l y and
c o n t i n u o u s l y i n f l u e n c e p a t t e r n s o f change,
development and e q u i l i b r i u m o f ecosystems.
S i m u l t a n e o u s l y , e v e r y a s p e c t o f t h e i r behavi o r a l p a t t e r n s a r e c o n d i t i o n e d by t h e f u n c t i o n a l a c t i v i t i e s o f t h e ecosystem.
Some d i s e a s e s a r e n o n s e l e c t i v e i n t h e i r
a c t i o n s of a l t e r i n g p l a n t communities w h i l e
others r e f l e c t varying degrees of s e l e c t i v i t y .
In e i t h e r c a s e , t h e a c t i o n o f d i s e a s e i n a l t e r i n g t h e s e communities i s l a r g e l y i n c o m p a t i b l e
w i t h man's d e s i r e s and o b j e c t i v e s f o r managing
t h e p l a n t s . T h e i r s i g n i f i c a n c e t o mankind i s
based mainly on l a n d u s e . The conspicuous
d i s a d v a n t a g e s o f t h e unplanned and m a i n l y unp r e d i c t a b l e n a t u r e o f d i s e a s e a c t i o n s masks
any i n s i d i o u s a d v a n t a g e s . Advantages do e x i s t ,
however.
E f f e c t s o f d i s e a s e s upon development o f
v e g e t a t i o n a r e h i g h l y v a r i a b l e . The magnitude
o f v a r i a t i o n becomes p e r c e p t i b l e when one
compares e n p h y t o t i c w i t h e p i p h y t o t i c d i s e a s e
c o n d i t i o n s , d i s e a s e s caused by e x o t i c v e r s u s
i n d i g e n o u s a g e n t s , o r t h e same d i s e a s e i n
d i f f e r e n t environments. T h i s v a r i a b i l i t y i s
r e f l e c t e d i n f l o r i s t i c s , succession, physiognomy, d e n s i t y , dominance, d i s t r i b u t i o n , v i t a l i t y , and v i g o r t h r o u g h o u t a l l s u c c e s s i o n a l
stages, finding i t s ultimate manifestation i n
productivity.
Indirectly, they strongly
i n f l u e n c e l a n d u s e and management d e c i s i o n s .
ECOLOGICAL APPROACH TO MANAGEMENT
AND SILVICULTURE
Success i n production of goods and servi c e s from t h e f o r e s t t o meet s o c i e t i e s ' needs
of t h e f u t u r e w i l l depend on man's a b i l i t y t o
develop and apply management p r a c t i c e s t h a t
minimize t h e e f f e c t s of diseases. To achieve
t h i s , we need t o re-examine our thinking and
expand our knowledge of j u s t what r e a l l y cons t i t u t e s a f o r e s t . I t i s more than a stand
of t r e e s o r a timber type. I t i s an associat i o n of plants t h a t represents the current
product o f a l l t h e i n t e r a c t i o n s of those
p l a n t s and t h e i r environment. I t f i t s t h e
synecologic concept of an ecosystem. We must
t h i n k i n terms of managing e n t i r e ecosystems.
We cannot succeed i f we continue our attempts
t o manage c e r t a i n segments, ignore some segments, and e r a d i c a t e s t i l l o t h e r segments
because t h e bonds of t h e s e segments a r e i n t e r locking and i n d i s s o l u b l e . Management pract i c e s t o minimize t h e e f f e c t s of d i s e a s e do
not e x i s t , f o r many d i s e a s e s i t u a t i o n s . In
f a c t , many c u r r e n t p r a c t i c e s optimize r a t h e r
than minimize t h e e f f e c t s of disease. Why do
such s i t u a t i o n s e x i s t ? There a r e two preval e n t reasons. E i t h e r we do not have t h e
information necessary t o develop t h e p r a c t i c e s
o r we a r e n o t applying t h e information t h a t i s
available.
I n an e a r l i e r p r e s e n t a t i o n , we heard s i l v i c u l t u r e defined a s t h e a r t and science of
c u l t u r i n g f o r e s t s . The a r t was described a s
' f l y i n g by t h e s e a t of your pants" and t h e
science described a s ecology. In t h e p a s t , we
have p e r p e t r a t e d a l o t of t h e former e i t h e r
under t h e d i s g u i s e of t h e l a t t e r o r t h e cloak
of ignorance. What we need now i s a b e t t e r
understanding and a p p l i c a t i o n of t h e l a t t e r .
To be successful i n t h i s endeavor means t h a t
we must accept and i n t e n t i o n a l l y p r o j e c t prot e c t i o n of t h e f o r e s t from d i s e a s e s and o t h e r
p e s t s a s an i n t e g r a l a c t i v i t y of s i l v i c u l t u r e .
This can be accomplished by using t h e ecosystems
concept a s our approach t o s i l v i c u l t u r e . This
has not been t h e p r e v a i l i n g concept and a t t i tude o f t h e p a s t and i s a major reason why we
a r e forever i n t r o u b l e with f o r e s t t r e e d i s eases. Such an approach may be d i f f i c u l t t o
follow f o r some geographic a r e a s of western
North America because t h e i r ecology has been
s o d r a s t i c a l l y disturbed by man t h a t t h e i r
ecosystems have d e t e r i o r a t e d beyond recognit i o n . Fortunately, t h i s i s not t h e case i n
t h e Northern Rocky Mountains, P a c i f i c Northwest, and Western Canada. Systems f o r c l a s s i f y i n g vegetation using synecological p r i n c i p l e s and concepts have been developed f o r
t h e s e a r e a s (Daubenmire and Daubenmire 1968;
P f i s t e r and o t h e r s 1977; Franklin and Dyrness
1969; Krajina 1969) and a s s u r e us t h e opport u n i t y t o apply t h e ecosystems approach t o t h e
practice of silviculture.
INVENTORY
In order t o properly manage a f o r e s t f o r
goods and s e r v i c e s , t h e land manager needs an
a p p r a i s a l of t h e t o t a l a r r a y of n a t u r a l r e sources encompassed by t h e f o r e s t . This app r a i s a l should be recorded i n both q u a l i t a t i v e
and q u a n t i t a t i v e terms. The manager needs t o
know what he has t o manage, where it i s l o c a t e d ,
and i t s condition. I view t h i s a s an ecological
inventory of t h e n a t u r a l resources t o be managed; a recording of d a t a t h a t can be accepted
a s representing t h e present ecology. Our curr e n t inventory systems of gathering information
f o r planning management a c t i o n do not s a t i s f y
t h e needs of t h e land manager. This is one o f
t h e reasons he i s "flying by t h e s e a t of h i s
pants." The land manager himself should not be
expected t o develop t h e technology and decide
what d a t a t o c o l l e c t . This should be done i n
consultation and cooperation with a research
organization t h a t can provide input from persons possessing specialized s k i l l s and knowledge of f o r e s t r y and r e l a t e d sciences. There
i s no need t o c o l l e c t d a t a t h a t has no u t i l i t y .
DATA INTERPRETATION AND UTILIZATION
Another t a s k confronting t h e land manager
i s understanding d a t a i n terms of p l a n t growth
and how he can use them t o achieve h i s object i v e s . After a l l , d a t a have l i t t l e meaning and
even l e s s u t i l i t y unless we can understand and
explain t h e i r o r i g i n . Again, t h i s t a s k must be
achieved i n concert with research. I f p e s t
control s t r a t e g i e s a r e required, they should be
i n t e g r a t e d with resource management a c t i v i t i e s .
I t i s imperative t h a t land managers and r e searchers work together on t h e s e a c t i v i t i e s and
not independently and i n i s o l a t i o n of one
another a s so o f t e n has occurred i n t h e p a s t .
Our ecological and s i l v i c u l t u r a l knowledge
of ecosystems i s very meager because of t h e
i n t r i c a t e complexity of such systems. We have
managed t o c o l l e c t and record some of t h e
simple, easy, and obvious information o f t h e i r
functioning.. A s t h e information becomes more
complex, c o r r e c t i o n s , a d d i t i o n s , and continuat i o n of t h i s record w i l l come more slowly and
with increasing d i f f i c u l t y . How do we r e s o l v e
t h i s dilemma?
I t has been suggested t h a t we s t a r t with
improvement and development of automated d a t a
processing and management systems t h a t w i l l
e f f i c i e n t l y handle i n f i n i t e d a t a e n t r i e s
(Waters 1975). Next, we need t o develop t h e
capability t o integrate the interlocking fragments of d a t a c o l l e c t e d on functional f a c t o r s
of ecosystems. I t appears t h a t mathematical
models composed of a s e r i e s of d i f f e r e n t i a l
equations can provide such c a p a b i l i t y . Such
models a r e being developed and t e s t e d f o r t h e
f o r e s t s of t h e Rocky Mountains (Meyers and
o t h e r s 1971; Stage 1973, -1975) f o r growth and
y i e l d p r e d i c t i o n s of goods and services. Models
t o be used f o r p r e d i c t i v e purposes and subsequent a c t i o n programs, r e q u i r e exacting, accur a t e , and r e l i a b l e , quantified data. Otherwise,
they a r e reduced t o j u s t another system of
generating guesstimates (Waters 1975). We have
t o o many of t h e s e now. With such a requirement,
one can r e a d i l y reason why we a r e i n a dilemma
with t h e dwarf m i s t l e t o e impact d a t a available.
In 1975, Intermountain S t a t i o n ' s Research
Work Unit 2205, Moscow, Idaho, established a
study t o quantify t r e e growth reduction i n t h e
Northern Rocky Mountain f o r e s t s r e s u l t i n g from
dwarf m i s t l e t o e i n f e c t i o n s . The objectives
were t o provide q u a n t i t a t i v e d a t a f o r a dwarf
m i s t l e t o e submodel t o t h e prognosis model f o r
stand development (Stage 1973) and t o develop
dwarf m i s t l e t o e growth l o s s curves. Preliminary
analyses of western l a r c h and Douglas-fir d a t a
a r e extremely encouraging f o r successful achievement of both objectives. I t i s i n t e r e s t i n g t o
n o t e t h a t t h e s e analyses show h a b i t a t type t o
be a highly s i g n i f i c a n t v a r i a b l e (P' = 0.01)
a f f e c t i n g height growth. The f i e l d work i s
expected t o continue f o r another 2 t o 3 summers
u n t i l t h e Northern Rocky Mountain f o r e s t s a r e
sampled.
Once acceptable automated d a t a processing,
management, and modeling systems a r e a v a i l a b l e ,
t h e f o r e s t inventory system must be updated.
Inventory must provide t h e q u a l i t y and type of
d a t a on t h e ecosystem needed by t h e land manager
t o e f f e c t i v e l y u t i l i z e t h e automated systems f o r
p r e d i c t i v e purposes and a s a i d s t o land management decisions.
SUMMARY
Continued increase of t h e population of
man i s r a p i d l y becoming a burden upon t h e n a t u r a l resources t h a t s u s t a i n l i f e by providing
man with food and s h e l t e r . We a r e being challenged t o increase p r o d u c t i v i t y of goods and
s e r v i c e s derived from f o r e s t s a t an inopportune
time when t h e t o t a l f o r e s t land base is r a p i d l y
shrinking. One way t o face t h i s challenge i s
t o recover those l o s s e s i n productivity due t o
p e s t s . P e s t s t h a t cause diseases a r e an i n t e g r a l p a r t of f o r e s t ecosystems. S t r a t e g i e s t o
r e g u l a t e t h e impact of diseases on f o r e s t prod u c t i v i t y must be i n t e g r a t e d with judiciously
planned a c t i v i t i e s of managing t h e t o t a l f o r e s t
ecosystem, not j u s t a segment. We can no longer
a f f o r d t o operate i n a realm of thinking where
a f o r e s t i s merely a group of t r e e s and i t s
p e s t s a r e a completely separate e n t i t y . The
e f f o r t s and knowledge of t h e land manager, t h e
p e s t c o n t r o l s p e c i a l i s t , and t h e research
s c i e n t i s t must be coordinated and i n t e g r a t e d
i n t o a systems approach t o f o r e s t land management. This w i l l r e q u i r e refinements and i m provements i n d a t a c o l l e c t i o n , processing,
i n t e r p r e t a t i o n , u t i l i z a t i o n , and a p p l i c a t i o n .
More important, it w i l l r e q u i r e recognition of
and respect f o r ecological r e a l i t y . Greater
s o p h i s t i c a t i o n i n automated d a t a processing and
mathematical modeling appears promising f o r
enhancing our c a p a b i l i t y t o process, i n t e r p r e t ,
and i n t e g r a t e t h e myriad of d a t a needed t o manage f o r e s t ecosystems a s a renewable n a t u r a l
resource.
LITERATURE CITED
Daubenmire, R . , and J . B. Daubenmire.
1968. Forest vegetation of e a s t e r n Washington and northern Idaho. Wash. Agric.
Exp. Stn. Tech. Bull. 60, 104 p.
Franklin, J . F., and C. T. Dyrness.
1969. Vegetation of Oregon and Washington.
USDA For. Serv. Res. Pap. PNW-80, 216 p.
P a c i f i c Northwest Forest and Range Exp.
Stn., Portland, Oreg.
Hawksworth, F . G .
1958. Survey of lodgepole pine dwarfmistlet o e on t h e Roosevelt, Medicine Bow, and
Bighorn National Forests. USDA For. Serv.,
Rocky Mountain For. and Range Exp. S t n . ,
Stn. Pap. 35, 13 p. F t . Collins, Colo.
Hawksworth, F. G . , and A. A. Lusher.
1956. Dwarfmistletoe survey and control on
t h e Mescalero-Apache Reservation, New
Mexico. J . For. 54:384-390.
Krajina, V. J .
1969. Ecology of f o r e s t t r e e s i n B r i t i s h
Columbia. Ecol. West. North Am. 2:l-147.
Meyers, C. A., F. G . Hawksworth, and J . L.
Stewart.
1971. Simulating y i e l d s of managed, dwarf
mistletoe-infected lodgepole pine stands.
USDA For. Serv. Res. Pap. RM-72, 15 p.
Rocky Mountain Forest and Range Exp. S t n . ,
Fort Collins, Colo.
P f i s t e r , R. D . , B. L. Kovalchik, S. F. Arno,
and R. C. Presby.
1977. Forest h a b i t a t types of Montana.
USDA For. Serv. Gen. Tech. Rep. INT-34,
174 p. Intermountain Forest and Range
Exp. S t n . , Ogden, Utah.
Pierce, W. R.
1960. Dwarf m i s t l e t o e and i t s e f f e c t upon
t h e l a r c h and Douglas-fir of western
Montana. Mont. S t a t e Sch. For. Bull.
10, 38 p.
S t a g e , A. R.
1973. P r o g n o s i s model f o r s t a n d development.
USDA For. Serv. Res. Pap. INT-137, 32 p.
I n t e r m o u n t i n F o r e s t and Range Exp. S t n . ,
Ogden, Utah.
Weir, J. R.
1916a. Larch m i s t l e t o e : some economic considerations of i t s injurious effects.
U.S. Dep. Agric. B u l l . 317, 25 p.
Weir, J. R.
S t a g e , A. R.
1975. P r e d i c t i o n o f h e i g h t increment f o r
models o f f o r e s t growth. USDA For. Serv.
Res. Pap. INT-164, 20 p.
Intermountain
F o r e s t and Range Exp. S t n . , Ogden, Utah.
Waters, W. E.
1975. F o r e s t p e s t management: p r e s e n t p r o s p e c t i v e ~and a l o o k ahead. I n Proc.
J o i n t Meetings 2 6 t h WFIWC a n d 2 2 n d WIFDWC,
Monterey, C a l i f . , p. 11-14.
USDA F o r e s t S e r v i c e .
1978. The Resources P l a n n i n g Act: A Program
Report. USDA For. S e r v . , 52 p.
1916b. M i s t l e t o e i n j u r y t o c o n i f e r s i n t h e
Northwest. U.S. Dep. Agric. B u l l . 360,
39 p.
Weir, J. R.
1916c. Some s u g g e s t i o n s on t h e c o n t r o l o f
mistletoe i n t h e National Forests of t h e
Northwest. For. Quar. 14:567-577.
Weir, J. R.
1918. E f f e c t s o f m i s t l e t o e on young c o n i f e r s .
J. Agric. Res. 12:715-718.