FOREST REGIONS OF MONTANA
STEPHEN F. ARNO
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USDA Forest Service Research Paper INT-218
INTERMOUNTAIN FOREST AND RANGE EXPERIMENT STATION
Forest Service U.S. Department of Agriculture Ogden, Utah 84401
USDA Forest Service
Research Paper INT-218
April 1979
FOREST REGIONS OF MONTANA
STEPHEN F. ARNO
INTERMOUNTAIN FOREST AND RANGE EXPERIMENT STATION
Forest Service
U. S. Department of Agriculture
Ogden, Utah 84401
THE AUTHOR
STEPHEN F. ARNO i s a Plant Ecologist on the F o r e s t Ecosystems
r e s e a r c h work unit at Missoula. He earned a B. S. in f o r e s t r y
at Washington State University and a m a s t e r ' s d e g r e e and a
Ph. D. in f o r e s t r y and plant science at the University of Montana before joining the F o r e s t Service in 1970.
ACKNOWLEDGMENTS
Robert Pfister (USDA F o r e s t Service Project Leader) gave
encouragement and advice throughout this study. The following fore s t e r s f r o m USDA F o r e s t Service, Northern Region, shared t h e i r
information on the distributions of indicator plants: Robert Bigler,
H e r b e r t Holdorf (Soil Scientist), John Joy, Bernard Kovalchik, Tom
Lawrence, Gary Learn, B. John Losensky, and J a m e s Schaeffer.
Similar information w a s provided by Joseph Antos, J a m e s Habeck,
and Pete Zager f r o m the Botany Department of the University of
Montana and by Tad Weaver, John Rumley, and Frank Forcella
f r o m Montana State University. In addition, I would like to thank
the many people who provided review comments during the development of t h i s manuscript.
Page
INTRODUCTION
..........................
..........
FOREST REGION DESCRIPTIONS . . . . . . . . . . . . . . . .
Northwestern Montana F o r e s t Region . . . . . . . . . . . .
West- Central Montana F o r e s t Region . . . . . . . . . . . .
North- Central Montana F o r e s t Region . . . . . . . . . . .
Central Montana F o r e s t Region . . . . . . . . . . . . . . .
Southwestern Montana F o r e s t Region . . . . . . . . . . . .
South- Central Montana F o r e s t Region . . . . . . . . . . . .
Southeastern Montana F o r e s t Region . . . . . . . . . . . .
Northeastern Montana F o r e s t Region . . . . . . . . . . . .
RESEARCH AND MANAGEMENT APPLICATIONS . . . . . . .
PUBLICATIONS CITED . . . . . . . . . . . . . . . . . . . . . .
DELINEATING MONTANA FOREST REGIONS
APPENDIX A.
DISTRIBUTION OF KEY TREE AND
UNDERGROWTH SPECIES IN MONTANA
APPENDIX B.
NUMBER OF SAMPLE PLOTS (PFISTER AND
OTHERS 1977) BY HABITAT TYPE. PHASE.
AND FOREST REGION IN MONTANA
....
......
APPENDIX C.
NATIONAL FORESTS. INDIAN RESERVATIONS.
AND NATIONAL PARKS WITHIN EACH FOREST
REGION IN MONTANA
..............
The author categorizes forest vegetation across Montana into eight geographic subdivisions called "forest regions. " The regions correlate the influence of climate and general topography to forest vegetation--including the
distributions of tree and undergrowth species and forest habitat types. The
vertical zonation of forest s e r i e s (based on the potential climax tree species)
also differs from one region to the next. Regional boundaries were fitted to
distributions of certain t r e e and undergrowth species, habitat types, and natural climatic b a r r i e r s such a s the Continential Divide and broad grassland
valleys that separate forest environments.
(1)The northwestern Montana forest region has major representation by
Pacific Coast species such a s Thujaplicata and Clintoniauniflora; its climate
is strongly influenced by moist maritime airmasses. (2) The west-central
region has a generally drier Pacific-influenced climate and only small amounts
of Pacific Coast species; however, i t has major representation of intermountain
plants like Larix occidentalis and Xerophyllum tenax.
(3) North-central Montana lies in the severe climate of the "chinook wind
belt" along the east slope of the Continental Divide. It is distinguished by
being too cold for Pinus ponderosa, but having extensive Populus tremuloides
groves and Pinus flexilis woodlands. (4) The central Montana forest region
has a l e s s severe continental climate and it supports the east-side forin of
Pinus ponderosa at lower elevations. However, both coastal and intermountain
species a r e essentially absent from its mountain forests.
-
Both the ( 5 ) southwestern and (6) south-central forest regions have high
base elevations and a r e without Pinus ponderosa. The former region's forests a r e generally d r i e r than the latter's and often have sparse undergrowth.
(7) Southeastern Montana differs from previously mentioned regions in not
having prominent mountains. It has extensive Great Plains Pinus ponderosa
forests. (8) Northeastern Montana i s a Great Plains area having no forest,
except for Populus deltoides groves along major streams.
The regions may be usefulas a biologically based stratification for forest research and forest management studies.
INTRODUCTION
T h i s r e p o r t d e s c r i b e s 'Montana's f o r e s t s by geographic s u b d i v i s i o n s c a l l e d " f o r e s t
r e g i o n s . I ' I t emphasizes p a t t e r n s i n s p e c i e s composition ( t r e e s and undergrowth) and
t h e r e l a t i o n s h i p o f t h e s e p a t t e r n s t o c l i m a t e and topography. The i n t e r p r e t a t i o n s a r e
based on f i e l d e x p e r i e n c e and d a t a c o l l e c t e d d u r i n g a r e c e n t f o r e s t h a b i t a t t y p e c l a s s i f i c a t i o n ( P f i s t e r and o t h e r s 1977).
There a r e two primary r e a s o n s f o r d e l i n e a t i n g t h e f o r e s t r e g i o n s of Montana.
F i r s t , t h e r e g i o n s s e r v e a s a geographic r e f e r e n c e f o r d e s c r i b i n g p a t t e r n s of f o r e s t
v e g e t a t i o n a c r o s s t h e S t a t e . Second, d e l i n e a t i n g t h e r e g i o n s c o n t r i b u t e s t o r e g i o n a l
c l a s s i f i c a t i o n s t h a t a r e b e i n g developed from a n a t i o n a l p e r s p e c t i v e ( B a i l e y 1976, 1978).
The geographic s u b d i v i s i o n s d i s c u s s e d i n t h i s paper a r e based on t h e d i s t r i b u t i o n of
f o r e s t v e g e t a t i o n i n r e l a t i o n t o c l i m a t e ( a s i n f l u e n c e d by topography). Thus, t h e s e
s u b d i v i s i o n s a r e proposed f o r u s e o n l y f o r i n t e r p r e t a t i o n s r e l a t e d t o f o r e s t v e g e t a t i o n .
A f t e r reviewing d e f i n i t i o n s provided i n Kuchler (1973) and B a i l e y (1976), t h e term
" f o r e s t region" seemed most a p p r o p r i a t e f o r u s e h e r e . "Region" i s a g e n e r a l term t h a t
does n o t n e c e s s a r i l y s p e c i f y a l e v e l i n t h e land c l a s s i f i c a t i o n h i e r a r c h y , and t h e term
" f o r e s t region" h a s been a p p l i e d i n Canada (Rowe 1 9 7 2 ) . ("Province" was a l s o c o n s i d e r e d ,
b u t i t h a s a more p r e c i s e h i e r a r c h i c a l d e f i n i t i o n r e l a t e d t o t h e dominant v e g e t a t i v e
t y p e s i n an a r e a , o r t o physiography; t h u s , some o f Montana's f o r e s t r e g i o n s o c c u r
within grassland provinces. j
Other r e g i o n a l d i v i s i o n s o f Montana have been developed from d i f f e r e n t t y p e s of
i n f o r m a t i o n t o meet d i f f e r e n t o b j e c t i v e s . Schmidt and Dufour (1975) emphasized geomorphology i n d e s i g n a t i n g s i x r e g i o n s w i t h i n Montana. Those r e g i o n s were used i n a s s e s s i n g
r e s e a r c h n a t u r a l a r e a needs from t h e f o l l o w i n g v i e w p o i n t s : f o r e s t v e g e t a t i o n , g r a s s
and shrubland v e g e t a t i o n , geology, zoology, and a q u a t i c s . Crowley (1972) d e p i c t e d seven
major environmental r e g i o n s w i t h i n Montana based on c h a r a c t e r i s t i c s of human e n v i r o n ments, i n c l u d i n g landforms, c l i m a t e , and e l e v a t i o n a l z o n a t i o n s o f v e g e t a t i o n .
S t i l l o t h e r s (Kuchler 1964; Payne 1973; Ross and Hunter 1976) have provided maps
o f Montana's n a t u r a l v e g e t a t i v e t y p e s ; but t h e maps a r e n o t focused on r e g i o n a l v a r i a t i o n i n f o r e s t v e g e t a t i o n . In c o n t r a s t t o t h e s e r e f e r e n c e s , t h e Montana " f o r e s t
r e g i o n s " proposed h e r e d e l i n e a t e r a t h e r broad a r e a s having s i m i l a r z o n a t i o n i n f o r e s t
v e g e t a t i o n . These f o r e s t r e g i o n s have g e n e r a l s i m i l a r i t i e s t o t h e f o r e s t d i s t r i c t s
d e s i g n a t e d by t h e e a r l y Montana b o t a n i s t , Kirkwood (1922), f o r d e s c r i b i n g f o r e s t d i s t r i b u t i o n i n t h e Northern Rocky Mountains.
During t h e Montana f o r e s t h a b i t a t t y p e s t u d y ( P f i s t e r and o t h e r s 1 9 7 7 ) , 1,500 s t a n d s
were sampled " s u b j e c t i v e l y without b i a s t ' (Mueller-Dombois and Ellenburg 1 9 7 4 ) . The
s t a n d s r e p r e s e n t a spectrum o f mature f o r e s t communities and s i t e s i n each mountain
r a n g e and f o r e s t e d a r e a of t h e S t a t e . A s t h e h a b i t a t t y p e c l a s s i f i c a t i o n was being developed from t h e s e d a t a , i t became obvious t h a t d i s t r i b u t i o n s o f many t r e e and undergrowth s p e c i e s (and t h u s t h e d i s t r i b u t i o n s o f t h e h a b i t a t t y p e s ) a r e s t r o n g l y c o r r e l a t e d
t o p a t t e r n s of geography and c l i m a t e w i t h i n Montana. I t became e v i d e n t t h a t t h e S t a t e
could be subdivided i n t o s e v e r a l r e l a t i v e l y homogeneous f o r e s t r e g i o n s based on t h e
d a t a , f i e l d o b s e r v a t i o n s , and i n f o r m a t i o n on p l a n t s p e c i e s d i s t r i b u t i o n s (Herbarium
c o l l e c t i o n s a t t h e U n i v e r s i t y o f Montana, Missoula; Montana S t a t e U n i v e r s i t y , Bozeman;
t h e USDA F o r e s t S e r v i c e F o r e s t r y S c i e n c e s L a b o r a t o r y , Missoula; p e r s o n a l i n t e r v i e w s
with l o c a l f o r e s t e r s and b o t a n i s t s ( s e e acknowledgments) ; Booth and Wright 1966,
Hitchcock and o t h e r s 1955-1969, L i t t l e 1971, 1 9 7 6 ) .
A map o f f o r e s t r e g i o n s ( c a l l e d " geographic s ~ b d i v i s i o n s ~was
~ ) p r e s e n t e d by P f i s t e r
and o t h e r s (1977), and a b r i e f account o f each h a b i t a t t y p e ' s d i s t r i b u t i o n was g i v e n by
r e g i o n . However, t h e b a s i s f o r t h e s e r e g i o n s was n o t d i s c u s s e d ; a l s o , Montana's f o r e s t
v e g e t a t i o n and environments were n o t d e s c r i b e d by r e g i o n . These t o p i c s a r e a d d r e s s e d
here.
The Canadian F o r e s t S e r v i c e (Rowe 1959, 1972) mapped and d e s c r i b e d " F o r e s t
Regions o f Canada," which p r o v i d e s a p r e c e d e n t . Rowe (1972) e x p l a i n e d t h a t t h e Canad i a n r e g i o n a l d e s i g n a t i o n s a r e g e n e r a l i z e d , w i t h t h e broad p e r s p e c t i v e o f Canada a s a
whole, a l t h o u g h t h e s t a t e m e n t was made t h a t it would be p o s s i b l e t o d e s i g n a t e such
r e g i o n s from a d e t a i l e d knowledge o f s p e c i f i c a r e a s i f d e t a i l e d d a t a e x i s t e d . The
l a t t e r approach i s used h e r e with d e t a i l e d d a t a from t h e h a b i t a t t y p e s t u d y ( P f i s t e r
and o t h e r s 1977) a s a b a s i s .
Kuchler (1973) d i s c u s s e d t e c h n i q u e s f o r d e s i g n a t i n g e c o l o g i c a l l y based " r e g i o n s . "
He s t a t e d t h a t c l a s s i f i c a t i o n s o f n a t u r a l v e g e t a t i o n t y p e s and d e t a i l e d mapping o f t h e i r
d i s t r i b u t i o n s a r e fundamental f o r e s t a b l i s h i n g such r e g i o n s .
( I t appears t h a t t h e
Montana f o r e s t h a b i t a t t y p e c l a s s i f i c a t i o n a l o n g w i t h t h e sample p l o t s and o t h e r d i s t r i b u t i o n a l d a t a can p r o v i d e t h i s b a s i c i n f o r m a t i o n . )
Kuchler ( 1 9 7 3 ) ~a l s o concluded t h a t
v e g e t a t i o n r e g i o n s should f i r s t be d e s i g n a t e d w i t h i n a l i m i t e d s t u d y a r e a , such a s a
S t a t e o r g e o g r a p h i c r e g i o n , and l a t e r expanded t o surrounding a r e a s .
Montana's f o r e s t s a r e b o t h e x t e n s i v e and d i v e r s e . F o r e s t c o v e r s n e a r l y o n e - f o u r t h
of Montana--about 2 3 m i l l i o n a c r e s a c c o r d i n g t o Green and S e t z e r (1974)--and s u b s t a n t i a l
amounts o f f o r e s t a r e found i n a l l but t h e n o r t h e a s t e r n p o r t i o n s o f t h e S t a t e ( f i g . 1 ) .
A t lower e l e v a t i o n s t h e s e f o r e s t s range from l u x u r i a n t s t a n d s of Tsuga heterophylla,
Thuja plicata, Pinus monticola, and o t h e r P a c i f i c Coast s p e c i e s i n n o r t h w e s t e r n Montana
t o open Pinus ponderosa woodlands on t h e Great P l a i n s of s o u t h e a s t e r n Montana. The
h i g h - e l e v a t i o n f o r e s t s a c r o s s t h e Montana Rockies a l s o show s u b s t a n t i a l v a r i a t i o n .
D i f f e r e n c e s i n c l i m a t e a r e p r i m a r i l y r e s p o n s i b l e f o r geographic v a r i a t i o n s i n t h e
p o t e n t i a l climax f o r e s t v e g e t a t i o n , expressed i n h a b i t a t t y p e s ( P f i s t e r and o t h e r s 1977).
The c l i m a t i c d i f f e r e n c e s a c r o s s Montana r e f l e c t t h e g r e a t e r importance o f P a c i f i c maritime a i r m a s s e s west o f t h e C o n t i n e n t a l Divide v e r s u s c o n t i n e n t a l c l i m a t i c c o n d i t i o n s
e a s t of t h e Divide. Locally, c l i m a t e (and t h u s f o r e s t v e g e t a t i o n ) a l s o i s s t r o n g l y i n f l u e n c e d by changes i n e l e v a t i o n , a s p e c t , and landform w i t h i n t h e Montana Rockies.
S o i l s and u n d e r l y i n g geology a l s o a f f e c t f o r e s t v e g e t a t i o n , b u t except f o r c e r t a i n limes t o n e s u b s t r a t e s and extremely rocky s i t e s , t h e e f f e c t s do n o t g e n e r a l l y obscure t h e
o v e r r i d i n g i n f l u e n c e o f c l i m a t e and topography.
The f o r e s t r e g i o n s o u t l i n e d on f i g u r e 1 c o r r e l a t e t h e i n f l u e n c e of c l i m a t e and
g e n e r a l topography t o f o r e s t v e g e t a t i o n - - i n c l u d i n g t h e d i s t r i b u t i o n s o f t r e e and undergrowth s p e c i e s and f o r e s t h a b i t a t t y p e s and t h e v e r t i c a l zonation of f o r e s t s e r i e s
( d i s c u s s e d l a t e r ) . Because t r e e s p e c i e s s e r v e a s i n d i c a t o r s o f c l i m a t e (Daubenmire and
Daubenmire 1968; P f i s t e r and o t h e r s 1977), t h e i r geographic d i s t r i b u t i o n s s e r v e a s a
primary d e t e r m i n a n t o f r e g i o n a l boundaries.
(Appendixes A-1 through A-6 i l l u s t r a t e how
t h e d i s t r i b u t i o n s o f t r e e s p e c i e s c o r r e l a t e w i t h Montana's f o r e s t r e g i o n s . ) D i s t r i b u t i o n s of undergrowth s p e c i e s t h a t have proved u s e f u l a s i n d i c a t o r p l a n t s i n major f o r e s t
h a b i t a t t y p e c l a s s i f i c a t i o n s i n t h e Northern Rockies ( R . and J . Daubenmire 1968;
P f i s t e r and o t h e r s 1977; and Robert S t e e l e and o t h e r s 1 ) , a l s o were used ( f o r examples,
s e e appendixes A-7 through A-10) .
I t became obvious t h a t many o f t h e t r e e , undergrowth p l a n t , and h a b i t a t t y p e d i s t r i b u t i o n s showed s i m i l a r p a t t e r n s , and r e l a t e t o known c l i m a t i c d i f f e r e n c e s (U.S. Department o f Commerce 1971; USDA S o i l Conservation S e r v i c e 1968). P r e l i m i n a r y r e g i o n a l
boundaries were drawn t o f i t t h e s e v e g e t a t i o n a l d a t a . The boundaries t h e n were a d j u s t e d
s l i g h t l y t o c o r r e l a t e w i t h n a t u r a l c l i m a t i c b a r r i e r s such a s t h e C o n t i n e n t a l Divide and
broad g r a s s l a n d v a l l e y s t h a t s e p a r a t e f o r e s t environments. Although t h e s e r e g i o n a l
boundaries were f i t t e d t o v e g e t a t i o n d a t a and t o t o p o g r a p h i c b a r r i e r s a s l o g 2 c a l l y a s
p o s s i b l e , sometimes t h e g e n e r a l p a t t e r n s of f o r e s t v e g e t a t i o n change g r a d u a l l y over
r a t h e r broad a r e a s . I n t h e s e c a s e s , where p o s s i b l e , major t o p o g r a p h i c f e a t u r e s were
used f o r f i n a l placement o f boundaries. Dashed l i n e s were used t o d e s i g n a t e r e g i o n a l
boundaries i n nonforested a r e a s .
The o c c u r r e n c e of t h e approximately 1,500 sample p l o t s by h a b i t a t t y p e and f o r e s t
r e g i o n i s summarized i n appendix B . P l a n t composition a t t h e s e f o r e s t s i t e s p r o v i d e s
b a s i c d a t a f o r r e g i o n a l b o u n d a r i e s . A t a broad l e v e l o f g e n e r a l i z a t i o n from t h i s d a t a
' ~ e v i e w d r a f t s of " F o r e s t h a b i t a t t y p e s of c e n t r a l Idaho" (1975) and t h o s e of t h e
Nezperce N a t i o n a l F o r e s t (1976). I n t e r m t . For. and Range Exp. S t n . , Ogden, IJtah.
FORESTED
-
WEATHERSTATIONS
1
Figure 1.--Montana f o r e s t regions and forested areas (from Hutchinson and Kemp 1952, Ross and Hunter 1976, composite
s a t e l l i t e photo o f Montana, GE Space Systems, B e l t s v i l l e , Md. J, Circled nwnbers are weather s t a t i o n s l i s t e d i n
table 4.
I a
[7 NONFOREST
T a b l e 1.--Extent (area covered) o f forest series (potential climax) i n each o f Montana's f o r e s t regions
A!
=
major
m = minor
r
=
rare
. = absent
:
Series
Tsuga and Thuja
Abies g r a n d i s
Picea
Pinus c o n t o r t a
P i n u s ponderosa
Pinus f l e x i l i s
Pseudotsuga
Abies l a s i o c a r p a
:
North- :
western :
West:
central :
North- :
central :
Forest region
: South- :
Central : western :
Soirthcentral
:
:
Southeastern
:
:
Northeastern
M
M
m
r
m
il
M
t h e e x t e n t ( a r e a covered) of each climax s e r i e s can be c o m p a r e d- - i d e n t i f i e d by t h e most
s h a d e - t o l e r a n t ( p o t e n t i a l climax) t r e e s p e c i e s c a p a b l e o f growing on a given s i t e .
Table 1 shows which s e r i e s o c c u r i n each o f t h e f o r e s t r e g i o n s . For i n s t a n c e , t h e
P a c i f i c Northwest c o a s t a l f o r e s t t y p e s (Thuja, Tsuga, and Abies grandis s e r i e s ) a r e o f
major importance o n l y i n n o r t h w e s t e r n Montana. Low-elevation f o r e s t t y p e s (Pinus ponderosa climax s e r i e s ) a s s o c i a t e d w i t h d r y , i n l a n d c l i m a t e s a r e abundant o n l y i n c e n t r a l
and s o u t h e a s t e r n Montana, and a r e a b s e n t o r r a r e i n t h e n o r t h - c e n t r a l , s o u t h w e s t e r n ,
and s o u t h - c e n t r a l f o r e s t r e g i o n s .
D e t a i l e d i n t e r p r e t a t i o n s (from appendix B d a t a ) a r e p r e s e n t e d i n t a b l e 2, which
shows t h e major h a b i t a t t y p e s i n each o f Montana's f o r e s t r e g i o n s . A d d i t i o n a l i n t e r p r e t a t i o n s and a d j u s t m e n t s were made i n developing t a b l e 2 from t h e sample p l o t d a t a
(appendix B). C e r t a i n s u b s t r a t e - o r i e n t e d h a b i t a t t y p e s (such a s PicealSenecio strept a n t h i f o z i u s and Abies Zasiocarpa/CZematis pseudoaZpina h . t . on l i m e s t o n e s u b s t r a t e s )
were h e a v i l y sampled by P f i s t e r and o t h e r s (1977), and a r e n o t a s e x t e n s i v e a s appendix
B i m p l i e s . Also, c e r t a i n a r e a s n e a r t h e b o r d e r of a f o r e s t r e g i o n were h e a v i l y sampled;
t h e r e b y more p l o t s were c o l l e c t e d from c e r t a i n h a b i t a t t y p e s t h a n a r e i n d i c a t i v e o f t h e
r e g i o n i n g e n e r a l . For i n s t a n c e , s e v e r a l Abies Zasiocarpa/CZintonia and Abies Zasiocarpa/XerophyZZwn h . t . p l o t s were t a k e n i n unusual l o c a t i o n s immediately e a s t o f t h e
C o n t i n e n t a l Divide i n n o r t h - c e n t r a l Montana.
The d i s t r i b u t i o n o f v a r i o u s t r e e s p e c i e s and undergrowth p l a n t s s e r v i n g a s h a b i t a t
t y p e o r c l i m a t i c i n d i c a t o r s i s p r e s e n t e d i n t a b l e 3 by f o r e s t r e g i o n a c r o s s Montana.
This t a b l e i s based on t h e 1,500 h a b i t a t t y p e p l o t s , and t h e f i e l d o b s e r v a t i o n s and
p u b l i s h e d i n f o r m a t i o n on p l a n t d i s t r i b u t i o n s c i t e d p r e v i o u s l y . The d i s t r i b u t i o n s of
P a c i f i c Coast and i n t e r m o u n t a i n s p e c i e s a r e u s e f u l f o r d i f f e r e n t i a t i n g f o r e s t s o f
n o r t h e r n Idaho, n o r t h w e s t e r n Montana, and w e s t - c e n t r a l Montana, but t h e o t h e r f o r e s t
r e g i o n s a r e c h a r a c t e r i z e d l a r g e l y by a l a c k of t h e s e s p e c i e s . (" Intermountain s p e c i e s "
a p p l i e s t o p l a n t s found most o f t e n between t h e c r e s t of t h e Cascade Mountains and t h e
C o n t i n e n t a l Divide.)
C e r t a i n widespread s p e c i e s ( l i k e Vacciniwn scopariwn, Juniperus conormnis, Arnica
cordifo l i a , Aster conspicuus, and even Pyro Za secunda) g e n e r a l 1y a r e accompanied by
P a c i f i c Coast o r i n t e r m o u n t a i n s p e c i e s west o f t h e C o n t i n e n t a l Divide; f a r t h e r e a s t t h e
c o a s t a l and i n t e r m o u n t a i n c o m p e t i t o r s d r o p o u t . T h i s s i t u a t i o n i s documented by t h e
changes i n h a b i t a t t y p e s d e p i c t e d i n t a b l e 2. For i n s t a n c e , Pseudotsuga/Junipems
c o r n i s , Pseudotsuga/l?rnica cordifozia, and Abies Zasiocarpa/Amica cordifoZia appear
o n l y e a s t of t h e Divide.
F i g u r e 2 shows a summary o f t h e c h a r a c t e r i s t i c s of each f o r e s t r e g i o n . The r e l a t i o n s h i p o f f o r e s t r e g i o n and N a t i o n a l F o r e s t b o u n d a r i e s i s shown i n appendix C.
Table 2.--Major habitat types ( P f i s t e r and others 1977) i n each o f J4mtana's f o r e s t
regions (See appendix B for more detailed information on a l l habitat t y p e s )
Habitat type
Forest region
Pinus flexilis/Festuca idahoensis
P. ponderosa/Agropyron spicatum
P. ponderosa/Festuca idahoensis
P. ponderosa/Symphoricarpos albus
P. ponderosa/Prunus virginiana
Pseudotsuga/Festuca idahoensis
Pseudotsuga/Festuca scabrella
Pseudotsuga/Vaccinium caespitosum
Pseudotsuga/Physocarpus malvaceus
Pseudotsuga/Vaccinium globulare
Pseudotsuga/Linnaea borealis
x
Pseudotsuga/Syn~phoricarpos albus
Pseudotsuga/Calamagrostis, Cal. phase
x
Pseudotsuga/Cal., other phases
x
x
Pseudotsuga/Spiraea betulifolia
Pseudotsuga/Arctostaphylos uva-ursi
Pseudotsuga/Juniperus communis
Pseudotsuga/Arnica cordifolia
Picea/Clintonia uniflora
Picea/Physocarpus malvaceus
Picea/Galium triflorum
Picea/Linnaea borealis
All Abies grandis h.t.s
Thuja plicata/Clintonia uniflora
Tsuga heterophylla/Clintonia uniflora
Abies
Abies
Abies
Abies
lasiocarpa/Clintonia uniflora
lasiocarpa/Galium triflorum
lasiocarpa/Calamagrostis canadensis
lasiocarpa/Linnaea borealis
Abies lasiocarpa/Menziesia ferruginea
All Tsuga mertensiana h.t.s
Abies lasiocarpa/Xerophyllum tenax
Abies
Abies
Abies
Abies
lasiocarpa/Vaccinium globulare
lasiocarpa/Vaccinium scoparium
lasiocarpa/Arnica cordifolia
1as.-Pinus albic./Vaccinium scop.
Abies
Pinus
Larix
Pinus
lasiocarpa/Luzula hitchcockii
albicaulis-Abies lasiocarpa
lyallii-Abies lasiocarpa
contorta community types
x
x
x
x
.
x
x
x
x
Table 3.--Distribution of selected t r e e s and undergrowth indicator plants by
forest region across Montana. ?iorthern Idaho data from Daubewnire
and Daubenmire (19 6 8 )
x = common
r = rare or scarce
= absent
.
Forest region
Species
:
:
Northern :
Idaho
: NW
:
WC
:
NC
:
C
:
SW
:
SC
:
SE
Coastal species
Adiantum pedatum
Asarum caudatum
Tsuga heterophylla
Tsuga mertsnsiana
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
Thuja plicata
Pinus monticola
Taxus brevifolia
Abies grandis
Clintonia uniflora
Intermountain species
Larix occidentalis
Larix lyallii
Pinus ponderosa
var . -ponderosal
Xerophyllum tenax
Menziesia ferruginea
Luzula hitchcockii
x
x
x
x
x
r
r
r
r
r
r
r
r
r
x
x
x
x
x
x
Widespread species
Widespread Rocky Mt.
trees2
Calamagrostis rubescens
Carex geyeri
x
x
x
x
x
x
x
x
x
x
x
x
x
Physocarpus malvaceus
x
x
x
r
x
r
x
r
x
r
r
x
x
x
x
x
x
x
x
x
Eastside species
Pinus flexilis
Senecio streptanthefolius
Frasera speciosa
Geranium richardsonii
.
x
x
x
x
Pinus ponderosa
var . scopulorum3
Juniperus horizontalis
Fraxinus pennsylvanica
x
x
x
x
r
x
x
x
r
(Little 19531, having three-needle fascicles only.
Pseudotsuga, Abies lasiocarpa, Picea, Pinus contorta, and Pinus albicaulis.
(Booth 1950 and Little 19531, having many two-needle fascicles.
7
a
var. ponderosa
70-110
b
80
Intermtn.
Species
90
Pacificcoast
Species
aspen
grovelands
rl
10
60-80
90-130
50
50-100
Continental
cold d r y
forests
cold moist
forests
@ @
25
40-70
Eastside Species
E. slope
P. ponderosa
20
var. scopulorum
0
Mountainous
*-
@ @
4
-
70-110 days
Modified Maritime
TRACE
Non forested
P. ponderosa
nonforest
Great P l a i n s and Eastern Species
20
I
00
var. scopulorum
+-i
100-130
Great P l a i n s
P
Figure 2. --Sumnary of the major characteristics of Montana's forest regions. (Average frost- free season, for s i t e s
with good a i r circuZation, as interpreted from Caprio 1 9 6 5 . )
DIAGNOSTIC
FOREST VEGETATION
PERCENT OF LAND FORESTED
LOWER ELEVATIONS
SUPPORT P i n u s ponderosa
FOREST TOPOGRAPHY
Average frost- free season
in lower elevation forests
DOMINANT CLIMATE
MONTANA FOREST REGION
Northwestern Montana
ForestRegion
The n o r t h w e s t e r n f o r e s t r e g i o n o f Montana i n c l u d e s t h e Kootenai, F l a t h e a d , and
lower C l a r k Fork River ( a s f a r upstream a s F i s h Creek and Ninemile Valley) d r a i n a g e s .
T h i s r e g i o n i s bounded on t h e e a s t by t h e C o n t i n e n t a l Divide, on t h e n o r t h by B r i t i s h
Columbia, and on t h e west and southwest by Idaho and t h e c r e s t o f t h e B i t t e r r o o t Mount a i n s . The s o u t h e a s t e r n b o r d e r of t h e r e g i o n i s marked by t h e R a t t l e s n a k e Creek and
Blackfoot R i v e r divTdes.
Diagnostic forest vegetation
The northwest f o r e s t r e g i o n h a s an abundance ( i n a l l b u t t h e d r i e r v a l l e y s ) o f
P a c i f i c Coast f o r e s t s p e c i e s t h a t a r e l e s s common o r a b s e n t elsewhere. Tree s p e c i e s
l a r g e l y r e s t r i c t e d t o t h i s r e g i o n i n c l u d e Tsuga heterophylla, T. mertensianu, Thuja
plicata, Abies grandis, Tams b r e v i f o l i a , and Pinus monticola. Undergrowth l a r g e l y
r e s t r i c t e d t o t h i s r e g i o n i n c l u d e s Clintonia uniflora, Aralia nudicaulis, Gymocarpiwn
dryopteris (and o t h e r P a c i f i c Coast f e m s ) , Dispomm hookeri, Tiarella t r i f o l i a t a ,
Viola glabella, and O p l o p a m horridwn (nomenclature i s from Hitchcock and Cronquist
1976).
Forest d i s t r i b u t i o n
AS i s t h e c a s e i n o t h e r mountainous s e c t i o n s o f Montana, t h e rugged t e r r a i n c r e a t e s
an a r r a y o f h a b i t a t s and accompanying v e g e t a t i o n , from s e m i a r i d g r a s s l a n d s i n t h e r a i n
shadow o f l a r g e mountain masses t o moist mountain v a l l e y s , s u b a l p i n e f o r e s t s , and a l p i n e
t u n d r a . The g e n e r a l i z e d d i s t r i b u t i o n o f f o r e s t t r e e s and climax s e r i e s f o r an a r e a i n
t h e Kootenai River d r a i n a g e i s d e p i c t e d i n f i g u r e 3. Major f o r e s t h a b i t a t t y p e s f o r
n o r t h w e s t e r n Montana a r e l i s t e d i n t a b l e 2 .
About 90 p e r c e n t of t h e l a n d i n t h i s r e g i o n i s p o t e n t i a l l y f o r e s t e d (Hutchison and
Kemp 1952; Green and S e t z e r 1974). Throughout much o f t h e r e g i o n , f o r e s t c o v e r s even
t h e lowest e l e v a t i o n v a l l e y s ( a s low a s 1,800 f e e t ) ; i n t h e d r i e s t v a l l e y s southwest o f
F l a t h e a d Lake, g r a s s l a n d p r e v a i l s below about 3,500 f e e t e l e v a t i o n . F o r e s t e x t e n d s over
a l l but t h e h i g h e s t peaks (and r o c k i e s t s i t e s ) . The average e l e v a t i o n o f a l p i n e t r e e
l i n e i s about 8,000 f e e t .
Figure 3.- - Distribution o f f o r e s t t r e e s i n a n area o f t h e Kootenai drainage i n northwestern Montana. Arrows show t h e r e l a t i v e e l e v a t i o n a l range o f each species;
s o l i d p o r t i o n o f t h e arrow i n d i c a t e s where s p e c i e s i s p o t e n t i a l climax, dashed
portion shows where it i s s e r a l . (Modified from P f i s t e r and o t h e r s 1977. )
Climatic i n f l u e n c e s
Northwestern Montana i s s t r o n g l y i n f l u e n c e d by moist maritime a i r m a s s e s t h a t
t y p i c a l l y f u n n e l through t h i s a r e a on t h e i r way i n l a n d from t h e P a c i f i c Coast (U.S.
Department of Commerce 1971; Daubenmire 1969). The a i r m a s s e s p r o v i d e abundant r a i n and
s n o w f a l l s and g e n e r a l l y humid, cloudy c o n d i t i o n s except i n midsummer. The a i r m a s s e s
a l s o b r i n g t h e r e l a t i v e l y mild w i n t e r t e m p e r a t u r e s (even a t h i g h e l e v a t i o n s ) t h a t a r e
n e c e s s a r y f o r t h e s u r v i v a l o f many of t h e c o a s t a l f o r e s t s p e c i e s .
The m i l d e s t c o n d i t i o n s a r e g e n e r a l l y a s s o c i a t e d w i t h t h e Kootenai d r a i n a g e i n t h e
western p a r t o f t h e r e g i o n . I n t h e Kootenai d r a i n a g e , f o r e s t s most n e a r l y resemble
t h o s e of a d j a c e n t n o r t h e r n Idaho, r e p r e s e n t i n g a s t i l l m o i s t e r and m i l d e r c o a s t a l c l i mate. Pinus monticola i s abundant and i s g e n e r a l l y t h e t a l l e s t and f a s t e s t growing
t r e e i n n o r t h e r n Idaho. However, eastward through n o r t h w e s t e r n Montana, Larix o c c i d e n t a l i s assumes t h i s r o l e ( a t t a i n i n g h e i g h t s of 150 t o 170 f e e t on f a v o r a b l e s i t e s ) .
F a r t h e r e a s t , i n t h e upper F l a t h e a d V a l l e y , o u t b r e a k s of a r c t i c a i r o c c u r more
f r e q u e n t l y i n t h e w i n t e r (1J.S. Department o f Commerce 1971). A s a r e s u l t , Tsuga h e t e r ophylla and Thuja s u s t a i n f r o s t damage and become r e s t r i c t e d t o s p e c i a l s i t e s . These
s i t e s e i t h e r have a c l i m a t e t h a t i s moderated by t h e p r e s e n c e of a l a r g e l a k e (Flathead
Lake and Lake McDonald) o r r e p r e s e n t s h e l t e r e d "cove" f o r e s t s i n r a v i n e s above t h e
v a l l e y bottom f r o s t zones. S t i l l , even i n t h e upper F l a t h e a d Valley, t r e e and undergrowth f l o r a r e f l e c t a P a c i f i c i n f l u e n c e extending a l l t h e way t o t h e C o n t i n e n t a l
Divide i t s e l f .
Weather r e c o r d s f o r Libby and Trout Creek ( t a b l e 4 ) r e p r e s e n t t h e m i l d e r , western
p a r t o f t h i s r e g i o n ; whereas t h e P o l e b r i d g e s t a t i o n l i e s i n t h e c o l d e r , upper Flathead
T a b l e 4.--Weather s t a t i o n records from Zower e z e v a t i o n forested s i t e s i n each o f E'ontana's forest regions.
Locations o f t h e s e s t a t i o n s are shotm b y nwnber f a t Zeftl on figure I
Region
and
station
: Fstimated :
: Mean ma. temp. : Ave. l e n g t h o f : Mean annu. : Mean May: climax
:
:
frost- free
: precipi: August
: series
: Elev. : J a n .
J u l y : s e a s o n - 32'F
:
tation
: precip.
Feet
O F
O F
Days
Northwestern
1. Libby (1NE)
2. T r o u t Creek (2W)
3. Polebridge
PSME
ABGR
PICEA
2,080
2,480
3,690
22
23
17
66
64
61
West - c e n t r a l
1. Darbv
. f2NNWl
.
,
2. Greenough
PIP0
PSME
3,815
4,000
25
18
65
63
--45
North-central
1. Babb (6NE)
2. B l a c k l e a f ( n e a r )
POTREM
PIFL
4,300
4,600
19
21
60
60
=60
Inches
Inches
: ~ e a n
: annual
: s n o w f a L
Inches
79
50
30
99
60
Central
1. H e l e n a
2. Lewistown
n e a r PIP0
PIP0
3,893
4,130
19
20
68
66
134
107
11
17
5.7
9.6
48
61
Southwestern
1. Lakeview
PSME
6,710
10
59
== 30
20
8.4
142
South-central
d r y e d g e o f PSME
Y e l l o w s t o n e N.P.
PICO-ABLA
2. M y s t i c Lake
PICO-ABLA
3 . W. Y e l l o w s t o n e
6,266
15
58
-90
16
7.7
El00
6,558
6,662
24
12
64
60
-- 95
-- 30
24
21
10.4
7.0
140
145
Southeastern
1 . Lame Deer
2. Roundup
3,331
3.227
22
24
70
72
=lo5
129
15
11
8.2
6.5
=36
2,277
11
72
124
13
7.8
36
1. Tower F a l l s
Northeastern
1. Glasgow
PIP0
PIP0
no f o r e s t
51
V a l l e y . Average annual p r e c i p i t a t i o n i n most of t h e s u b a l p i n e f o r e s t s of t h i s r e g i o n
r a n g e s from about 4 0 t o 65 i n c h e ~ . ~
West-Central Montana
Forest Region
The w e s t - c e n t r a l f o r e s t r e g i o n i n c l u d e s t h e Clark Fork River d r a i n a g e from t h e
Missoula-Frenchtown Val 1ey upstream, except f o r t h e C o n t i n e n t a l Divide range from Nevada
Peak (northwest o f Helena) t o C a l i f o r n i a Pass ( s o u t h o f Anaconda). This r e g i o n i s
bounded on t h e west by t h e l o f t y B i t t e r r o o t Range. The B i t t e r r o o t Range forms t h e Montana- Idaho Divide and c o n s t i t u t e s a s i g n i f i c a n t b a r r i e r t o P a c i f i c Coast m o i s t u r e and
thus t o coastal plants.
' ~ h e s e e s t i m a t e s were based on U.S. Dep. Comm. (1971), U.S. Dep. Comrn. weather
s t a t i o n d a t a , USDA S o i l Conserv. S e r v . (1968), Arno (1970), and an i s o h y e t a l a n a l y s i s
f o r t h e Columbia River d r a i n a g e p r e p a r e d by t h e U.S. Weather Bureau R i v e r F o r e c a s t Cent e r , P o r t l a n d , Oregon, i n 1968.
11
Diagnostic f o r e s t vegetation
Although i t h a s a r e l a t i v e l y m i l d , P a c i f i c - i n f l u e n c e d c l i m a t e , t h i s r e g i o n ' s f o r e s t s a r e g e n e r a l l y d r i e r t h a n t h o s e o f e i t h e r n o r t h w e s t e r n Montana o r a d j a c e n t n o r t h e r n
Idaho. Thus, t h e r e g i o n h a s o n l y small amounts o f P a c i f i c Coast f o r e s t s p e c i e s such a s
Thuja p l i c a t a , Pinus monticola, T m s b r e v i f o l i a , Clintonia u n i f l o r a , Adenocaulon b i color, Coptis spp. (of western North America), and T i a r e l l a t r i f o l i a t a . These s p e c i e s
a r e r e s t r i c t e d t o moist canyon-bottom s i t e s o r seepage a r e a s and g e n e r a l l y r e a c h t h e i r
s o u t h e a s t e r n l i m i t s w i t h i n t h i s r e g i o n ( t a b l e 3 ) . Abies grandis i s l o c a l l y common, b u t
i s much l e s s abundant t h a n it i s i n n o r t h w e s t e r n Montana. W e s t - c e n t r a l Montana i s c h a r a c t e r i z e d by an abundance o f t h e i n t e r m o u n t a i n f o r e s t s p e c i e s - - L a r i x o c c i d e n t a l i s , Larix
l y a l l i i , Pinus ponderosa v a r ponderosa, Xerophyllwn tenax, Menziesia fermginea, and
Luzula h i t c h c o c k i i . These s p e c i e s become r a r e o r a b s e n t i n t h e remaining r e g i o n s t h a t
l i e farther east (table 3 ) .
.
Forest d i s t r i b u t i o n
As f i g u r e 4 shows, t h e t y p i c a l a r r a y o f f o r e s t s e r i e s h e r e i s n o t a s d i v e r s e a s
t h a t i n n o r t h w e s t e r n Montana, because o f t h e s c a r c i t y o f P a c i f i c Coast s p e c i e s . About
Figure 4.- - Distribution o f f o r e s t t r e e s i n an area o f west- central Montana. Arrows
show t h e r e l a t i v e elevational range o f each species; s o l i d portion o f the arrow
i n d i c a t e s where a species i s the potential climax and dashed portion shows where
it i s seral. (Modified from P f i s t e r and o t h e r s 1 9 7 7 ) .
80 p e r c e n t o f t h e l a n d i n t h i s r e g i o n i s p o t e n t i a l l y f o r e s t e d . Most o f t h e n o n f o r e s t
land i s g r a s s l a n d (Agropyron spieatwn, Festuea idahoensis, and F . scabrella a s s o c i a t i o n s
o f Mueggler and Hand1 ( I n p r e s s ) ) t h a t o c c u r i n t h e b r o a d e r l o w - e l e v a t i o n v a l l e y s .
Annual p r e c i p i t a t i o n on t h e s e n o n f o r e s t v a l l e y s i t e s i s l e s s t h a n 15 inches and s o i l s
a r e w e l l - d r a i n e d . However, t h i s g r a s s l a n d i s n o t e x t e n s i v e , and lower t i m b e r l i n e
g e n e r a l l y o c c u r s w i t h i n 1,000 f e e t o f t h e v a l l e y b a s e e l e v a t i o n ; t h u s i t i s found
between a b o u t 3,200 and 5,500 f e e t . F o r e s t extends o v e r a l l b u t t h e h i g h e s t peaks
(and r o c k i e s t s i t e s ) . The average e l e v a t i o n of a l p i n e t r e e l i n e i s about 8,800 f e e t .
P r i n c i p a l f o r e s t h a b i t a t t y p e s o f w e s t - c e n t r a l Montana a r e shown i n t a b l e 2.
Climatic influences
The comparatively d r y , P a c i f i c - i n f l u e n c e d c l i m a t e o f t h i s r e g i o n i s i l l u s t r a t e d by
d a t a from t h e l o c a t i o n s o f Darby and Greenough ( t a b l e 4 ) . Average annual p r e c i p i t a t i o n
i n t h e s u b a l p i n e f o r e s t s i s g e n e r a l l y 35 t o 55 i n c h e s ( f o o t n o t e 2 ) .
S e r a 1 Pinus ponderosa and Larix occidentalis form t h e l a r g e s t and most commercially
important w e s t - c e n t r a l Montana f o r e s t t r e e s ; t h e y o f t e n a t t a i n h e i g h t s of 130 t o 140
f e e t a t m a t u r i t y . The exception i s t h e s o u t h e a s t e r n p a r t of t h i s r e g i o n where v a l l e y
b a s e e l e v a t i o n s a r e h i g h and f o r e s t s a r e doninated by Pinus contorts. (However, t h e
intermountain undergrowth s p e c i e s dominate.)
North-Central Montana
Forest Region
The n o r t h - c e n t r a l Montana f o r e s t r e g i o n i n c l u d e s a l l t h e f o r e s t e d t e r r a i n a l o n g
t h e e a s t s l o p e of t h e C o n t i n e n t a l Divide from t h e d r a i n a g e of t h e North Fork o f t h e
Dearborn River n o r t h t o t h e Canadian b o r d e r and e a s t t o Havre. Adjacent s o u t h e r n
A l b e r t a h a s s i m i l a r f o r e s t environments.
Diagnostic forest vegetation
T h i s a r e a s u p p o r t s t h e most e x t e n s i v e Populus tremuloides groves i n t h e S t a t e
(Lynch 1955) a s well a s l a r g e p a t c h e s o f Pinus flercilis woodland a l o n g t h e lower s k i r t s
o f t h e mountains. Pinus ponderosa i s a b s e n t , a p p a r e n t l y because of t h e e x c e s s i v e l y c o l d
and windy w i n t e r c o n d i t i o n s . A narrow band of Abies lasiocarpa ( s e r i e s ) f o r e s t a l o n g
t h e Rocky Mountain f r o n t s u p p o r t s t h e easternmost o c c u r r e n c e s of i n t e r m o u n t a i n undergrowth s p e c i e s , Menziesia ferruginea, Xerophyllwn tenax, Luzula hitchcockii, and even
"cove s i t e s " w i t h Clintonia unifZora b a r e l y extending a c r o s s t h e Divide from n o r t h w e s t e r n Montana (appendixes A- 7, -8, and - 10); however, t h e l i m i t e d t r e e f l o r a and i t s
s t u n t e d growth a r e d e f i n i t e l y i n d i c a t i v e o f t h e s e v e r e e a s t s i d e c l i m a t i c c o n d i t i o n s .
ELEVATIONS
(approx. 1
a.l
L
U
ru
111
U
alpine t u n d r a
6000
-
:.
l,I
LAS IOCARPA
SERIES
PSEUDOTSUGA SERIES
5000
4000
-
Populus tremuloides grovelands
Northern Great Plains grassland
Figure 5.--Distribution of forest t r e e s i n an area of north-central Montana. Arrows
show the r e l a t i v e elevationul range of each species; solid portion of the arrow
indicates where a species i s t h e potential climax and dashed portion shows where
it i s seral.
Forest d i s t r i b u t i o n
Only about 10 percent of t h e land i n t h i s region i s p o t e n t i a l l y f o r e s t e d , most of
it occurring i n a 20 t o 30 mile band along t h e e a s t e r n s k i r t s of t h e Continental Divide
o r Front Range of t h e Rockies. Figure 5 i l l u s t r a t e s a c h a r a c t e r i s t i c d i s t r i b u t i o n of
t r e e species i n t h i s region. A small area of s i m i l a r f o r e s t (8 mi 2 ), lacking only Lap&
Z y a l l i i , occurs on t h e Sweetgrass H i l l s (elev. 6,983 f e e t ) 90 miles e a s t of t h e n e a r e s t
Front Range stands (Thompson and Kuijt 1976).
Lower timberline generally occurs between 4,500 and 5,000 f e e t and f o r e s t extends
up t o a l l but t h e highest ridges and peaks. Alpine t r e e l i n e averages about 8,000 f e e t .
Most of t h e nonforest land i s p o t e n t i a l l y grassland dominated by Agropyron, Festuca,
Bouteloua, and Stipa (Kuchler 1964; Mueggler and Handl, In p r e s s ) .
Climatic influences
North-central Montana has a continental climate with severe chinook winds and dramatic f l u c t u a t i o n s of winter temperatures t h a t o f t e n i n j u r e f o r e s t t r e e s . On windexposed slopes, t r e e growth i s stunted by "red b e l t " conditions. Branches, groups of
t r e e s , o r even s i z a b l e stands a r e r o u t i n e l y k i l l e d by desiccation of f o l i a g e caused when
warm, dry chinook winds occur while t h e ground i s frozen and l i t t l e water i s a v a i l a b l e
t o replace t r a n s p i r a t i o n l o s s e s . Pinus f l e x i l i s ( a t low and middle elevations) and P.
albicaulis ( a t high elevations) a r e l e a s t susceptible t o red b e l t damage.
Growing s e a s o n s a r e s h o r t and c o o l i n t h e lower e l e v a t i o n f o r e s t s i t e s ( t a b l e 4
and f i g u r e 2 ) . Except i n p r o t e c t e d v a l l e y s , t r e e s seldom r e a c h 70 f e e t i n h e i g h t .
Average annual p r e c i p i t a t i o n i n t h e s u b a l p i n e f o r e s t s i s g e n e r a l l y 30 t o 40 i n c h e s
( f o o t n o t e 2 ) , a l t h o u g h i t i s much g r e a t e r i n a few a r e a s a l o n g t h e C o n t i n e n t a l Divide,
p a r t i c u l a r l y i n G l a c i e r National Park. The s e v e r i t y o f w i n t e r t e m p e r a t u r e f l u c t u a t i o n s
i s i l l u s t r a t e d by t h e world- record t e m p e r a t u r e d r o p of 100" F i n 24 hours (from +44" t o
-56°F) a t Browning, n e a r East G l a c i e r Park, i n J a n u a r y 1916 (McWhirter and McWhirter
1972).
Central Montana
Forest Regioln
The c e n t r a l Montana f o r e s t r e g i o n i n c l u d e s a l l t h e f o r e s t e d t e r r a i n from t h e Helena
Valley e a s t t o Harlowton, Lewistown, and F o r t Peck R e s e r v o i r , and n o r t h t o Havre. Spec i f i c a l l y , t h e w e s t e r n edge r u n s a l o n g t h e C o n t i n e n t a l Divide from t h e d r a i n a g e of t h e
Middle Fork o f t h e Dearborn River s o u t h t o t h e Boulder River d i v i d e . F o r e s t s contiguous
w i t h and west o f t h e d i v i d e a r e i n c l u d e d from t h e Avon V a l l e y s o u t h t o Deer Lodge (from
Nevada Peak t o E l e c t r i c Peak a l o n g t h e C o n t i n e n t a l Divide). Eastward, t h e a r e a encomp a s s e s t h e Elkhorn Mountains (except f o r t h e southwestern p o r t i o n o f t h a t range t h a t
d r a i n s i n t o t h e Boulder River) a s well a s t h e Big B e l t , L i t t l e B e l t , C a s t l e , Big Snowy,
L i t t l e Snowy, J u d i t h , L i t t l e Rocky, Bearpaw, and Highwood Mountains. The range a l s o
c o n t a i n s r a t h e r e x t e n s i v e lowland Pinus ponderosa (var. scopulorwn, Booth 1950, L i t t l e
1953) f o r e s t s i n t h e Helena and Lewistown v i c i n i t i e s and i n t h e Missouri River Breaks.
Diagnostic forest vegetation
Most o f c e n t r a l Montana h a s a l o w - e l e v a t i o n f o r e s t b e l t o f Pinus ponderosa ( v a r .
In c o n t r a s t t o w e s t s i d e P. ponderosa ( v a r . ponderosa), t h e s e have many
two- needle f a s c i c l e s and a s h o r t growth form. A d d i t i o n a l l y , c e n t r a l Montana h a s mount a i n f o r e s t s made up o f o t h e r climax s e r i e s ( t a b l e 1 ) . The o t h e r e a s t s i d e r e g i o n
c o n t a i n i n g P. ponderosa ( s o u t h e a s t e r n Montana) does n o t have a d d i t i o n a l f o r e s t s e r i e s .
scopulorwn).
C o a s t a l and i n t e r m o u n t a i n s p e c i e s a r e e s s e n t i a l l y a b s e n t , while e a s t s i d e s p e c i e s ,
i n c l u d i n g Pinus fZexiZis and Juniperus horizontalis, a r e prominent ( t a b l e 3 ) . Great
P l a i n s g r a s s l a n d elements such a s BouteZoua g r a c i l i s and B. curtipendula, Yucca glauca,
and Opuntia fragiZis, and 0. polyacantha a r e commonly found i n t h e d r i e s t Pinus ponderosa and P. f l e x i l i s s t a n d s .
Forest d i s t r i b u t i o n
Approximately 20 p e r c e n t o f t h e l a n d i n t h i s r e g i o n i s p o t e n t i a l l y f o r e s t e d . Most
o f t h e n o n f o r e s t l a n d i s p o t e n t i a l l y g r a s s l a n d dominated by Agropyron, Festuca, BouteZowz, and Stipa (Kuchler 1964; Mueggler and Handl, I n p r e s s ) . The f o r e s t s a r e
a s s o c i a t e d w i t h prominent mountain r a n g e s and t h e Missouri River Breaks. F o r e s t extends
from v a l l e y b a s e l e v e l s o r from lower t i m b e r l i n e s on t h e p r i n c i p a l mountain r a n g e s ( a t
4,000 t o 5,500 f e e t ) and c o v e r s a l l b u t t h e h i g h e s t peaks. Alpine t r e e l i n e a v e r a g e s
about 8,500 f e e t . F i g u r e 6 shows a c h a r a c t e r i s t i c d i s t r i b u t i o n of t r e e s p e c i e s on nonl i m e s t o n e p a r e n t m a t e r i a l s i n c e n t r a l Montana.
Figme 6.--Distribution of forest t r e e s i n an area of central Montana. Arrows show the
r e l a t i v e elevational range of each species; solid portion of the arrow indicates where
a species i s the potential climax and dashed portion shows where it i s seral.
Extensive a r e a s having limestone s u b s t r a t e s occur i n t h e mountain r a n g e s o f c e n t r a l
Montana. The limestone- derived s o i l s d r a i n r a p i d l y and a r e g e n e r a l l y dominated by
d r i e r s i t e s p e c i e s t h a n t h e a d j a c e n t nonlimestone s i t e s ( f i g . 53, 54, i n P f i s t e r and
o t h e r s 1977). For example, a t medium e l e v a t i o n s t h e limestone s i t e s o f t e n support
Pseudotsuga with a g r a s s - f o r b undergrowth, while a d j a c e n t g r a n i t i c s i t e s have Pinus
contorta and Vacciniwn spp. (Goldin and Nimlos 1977; Weaver and Parry 1978).
Climatic influences
This r e g i o n h a s a c o n t i n e n t a l c l i m a t e , b u t has f o r e s t s extending t o lower e l e v a t i o n s and l e s s s e v e r e w i n t e r c o n d i t i o n s than n o r t h - c e n t r a l Montana. The warmer J u l y
temperatures and l o n g e r growing s e a s o n s ( f i g . 2) i n t h e lower f o r e s t zone a r e
i n d i c a t e d by weather s t a t i o n d a t a i n t a b l e 4 . However, except on s h e l t e r e d s i t e s ,
t r e e s seldom a t t a i n 80 f e e t i n h e i g h t . Average annual p r e c i p i t a t i o n i n t h e s u b a l p i n e
f o r e s t s i s e s t i m a t e d t o be 25 t o 35 i n c h e s ( f o o t n o t e 2 ) .
I n t h e h i g h e r v a l l e y s and a t high e l e v a t i o n s i n t h e mountains, extreme temperature
changes accompanied by s t r o n g winds i n f l i c t r e d b e l t damage. For i n s t a n c e , i n midJanuary 1971 such weather c o n d i t i o n s (temperatures f l u c t u a t i n g between -30" and +58" F
a t Great F a l l s , accompanied by s t r o n g winds) k i l l e d about 20,000 a c r e s o f Pinus contorta
f o r e s t i n t h e L i t t l e B e l t Mountains.
I
b
Southwestern Montana
Forest Region
Area included
The s o u t h w e s t e r n Montana f o r e s t r e g i o n i n c l u d e s t h e J e f f e r s o n , Madison, and Boulder
River d r a i n a g e s , e a s t o f t h e C o n t i n e n t a l Divide, a s w e l l a s t h e f o r e s t s on b o t h s l o p e s
o f t h e C o n t i n e n t a l Divide r a n g e i n t h e v i c i n i t y o f B u t t e ( s p e c i f i c a l l y from E l e c t r i c
Peak, e a s t o f Deer Lodge, t o C a l i f o r n i a P a s s , s o u t h o f Anaconda).
A s i n c e n t r a l Montana, P a c i f i c Coast f o r e s t e l e m e n t s a r e a b s e n t and i n t e r m o u n t a i n
elements a r e s c a r c e ( t a b l e 3 ) . R a t h e r s h o r t , b u t s t o u t Pseudotsuga ( o r Pinus f l e x i l i s )
occupy t h e warmest f o r e s t s i t e s , and Pinus contorta a l o n g w i t h Vacciniwn scopariwn
undergrowth dominate most h i g h - e l e v a t i o n f o r e s t s . Undergrowth i s n o t a b l y s p a r s e i n t h e
d e n s e r f o r e s t s t a n d s , and i n Pseudotsuga f o r e s t s undergrowth o f t e n c o n s i s t s p r i m a r i l y
o f s c a t t e r e d Festuca idahoensis and even Artemisia t r i d e n t a t a
F i g u r e 7 shows a c h a r a c t e r i s t i c d i s t r i b u t i o n o f t r e e s p e c i e s i n s o u t h w e s t e r n Montana. P r i n c i p a l f o r e s t
h a b i t a t t y p e s a r e shown i n t a b l e 2 .
.V)
TORTA SERIES
uncertain)
MENZIESII SERIES
-
6000
grassland
Figure 7.- - Distribution of forest t r e e s i n an area of southwestern Montana. Arrows show
the r e l a t i v e elevationai! range of each species; solid portion of the arrow i n d i c a t e s
where a species i s the potential climax and dashed portion shows where it i s seral.
Forest distribution
D e s p i t e i t s mountainous t e r r a i n , o n l y a b o u t o n e - f o u r t h o f t h i s r e g i o n i s f o r e s t e d .
Most o f t h e n o n f o r e s t l a n d i s s e m i a r i d s t e p p e ( A r t e h s i a ) and g r a s s l a n d (Agropyron,
F e s t u c a , and S t i p a ) , a l o n g w i t h s m a l l a r e a s of a l p i n e v e g e t a t i o n (Kuchler 1964; Mueggler
and Handl, I n p r e s s ) above 9,500 f e e t e l e v a t i o n . Lower t i m b e r l i n e g e n e r a l l y o c c u r s
somewhere between 5,700 and 7,000 f e e t i n e l e v a t i o n . However, some o f t h e mountain
r a n g e s s o u t h o f D i l l o n a r e s o d r y t h a t l i t t l e f o r e s t i s s u p p o r t e d even a t 8,000 f e e t .
Thus, t h e e n t i r e f o r e s t b e l t (between lower and upper t i m b e r l i n e ) may span o n l y 1,000
t o 1,500 f e e t of e l e v a t i o n , and may b e l o c a l l y a b s e n t on exposed s o u t h - and w e s t - f a c i n g
s l o p e s . S i m i l a r l y h i g h , s e m i a r i d mountain r a n g e s , p r o j e c t i n g above a n A r t e m i s i a
t r i d e n t u t a s t e p p e (Kuchler 1964), o c c u r i n a d j a c e n t e a s t - c e n t r a l Idaho ( S t e e l e and
others (footnote 1 ) ) .
Climatic influences
A s i l l u s t r a t e d by weather r e c o r d s from Lakeview ( t a b l e 4 ) , t h i s i s a c o l d , d r y
f o r e s t r e g i o n h a v i n g h i g h v a l l e y - b a s e e l e v a t i o n s , and a c o n t i n e n t a l c l i m a t e . Average
a n n u a l p r e c i p i t a t i o n i n t h e s u b a l p i n e f o r e s t r a n g e s from a b o u t 22 t o 35 i n c h e s ( f o o t n o t e 2 ) . T h i s f o r e s t r e g i o n e v i d e n t l y h a s growing s e a s o n s t o o s h o r t and c o l d f o r
P i n u s p o n d e r o s a ( f i g . 2 ) . The c o l d , d r y c o n d i t i o n s a r e a l s o evidenced by t h e l a c k o f
P s e u d o t s u g a / P h y s o c q u s h a b i t a t t y p e ( t a b l e s 2 and 3 ) . However, chinook winds and temp e r a t u r e f l u c t u a t i o n s a r e l e s s s e v e r e t h a n i n n o r t h - c e n t r a l and c e n t r a l Montana, and
r e d b e l t damage i s l e s s common.
south-central Montana
Forest Region
The s o u t h - c e n t r a l Montana f o r e s t r e g i o n i n c l u d e s t h e G a l l a t i n and upper Yellowstone
R i v e r d r a i n a g e s ( a l o n g w i t h t h e B r i d g e r and Crazy Mountains) a s w e l l a s t h e P r y o r Mount a i n s and t h e n o r t h end o f t h e Bighorn Range. The r e g i o n encompasses t h e n o r t h e r n p a r t
o f an e x t e n s i v e , h i g h - e l e v a t i o n f o r e s t e d upland s u r r o u n d i n g Yellowstone N a t i o n a l Park.
T h i s upland i s capped by l a r g e a l p i n e p l a t e a u s i n Montana and Wyoming.
Diagnostic f o r e s t vegetation
Most of t h e f o r e s t i n s o u t h - c e n t r a l Montana i s dominated by Pseudotsuga, P i n u s
c o n t o r t u , P i c e a , o r A b i e s l a s i o c q a . The abundance o f P i c e a l P h y s o c a r p u s , Picea/Galium
t r i f l o r w n , A b i e s lasiocarpa/GaZiwn t r i f l o r w n , and A b i e s lasiocarpa/CaZwnagrostis canad e n s i s h a b i t a t t y p e s ( t a b l e 2) a t t e s t s t o t h e m o i s t n e s s o f many o f t h e f o r e s t s . Also,
s c a t t e r e d p o p u l a t i o n s o f Xerophyllwn and M e n z i e s i a (appendixes A-9 and -10) a r e found
h e r e , more t h a n 100 m i l e s e a s t o f t h e i r u s u a l d i s t r i b u t i o n a l l i m i t s n e a r t h e C o n t i n e n t a l
D i v i d e . In c o n t r a s t t o southwest Montana, o n e seldom f i n d s e x t e n s i v e s t a n d s h a v i n g a
g r a s s l a n d undergrowth ( e x c e p t on l i m e s t o n e s u b s t r a t e s ) , n o r d o e s one f i n d v e r y s p a r s e
undergrowth r e l a t e d t o d r y c o n d i t i o n s .
I
Forest distribution
I
Nearly h a l f o f t h e l a n d i n s o u t h - c e n t r a l Montana s u p p o r t s f o r e s t , and most of t h e
r e m a i n i n g a r e a i s p o t e n t i a l l y grassland--(Agropyron, F e s t u c a , S t i p a ) a c c o r d i n g t o
ELEVATIONS
(approx )
Figure 8.- - Distribution o f forest t r e e s i n an area of south- central Montana. Arrows
show t h e r e l a t i v e elevational range o f each species; s o l i d portion o f t h e arrow
i n d i c a t e s where a species i s t h e potential climax and dashed portion shows where
it i s s e r a l . (Modified from P f i s t e r and others 1977.1
Kuchler (1964)- - occupying t h e d r i e r , lower e l e v a t i o n v a l l e y s . Lower t i m b e r l i n e a v e r a g e s about 5,500 f e e t and a l p i n e t r e e l i n e o c c u r s n e a r 9,500 f e e t . F i g u r e 8 shows a
c h a r a c t e r i s t i c d i s t r i b u t i o n of t r e e s p e c i e s i n an a r e a o f s o u t h - c e n t r a l Montana. Table
2 lists principal f o r e s t h a b i t a t types.
Limestone s u b s t r a t e s a r e abundant i n t h e Pryor Mountains and occur s p o r a d i c a l l y
elsewhere i n s o u t h - c e n t r a l Montana. These s i t e s , below about an 8 , 0 0 0 - f o o t e l e v a t i o n ,
g e n e r a l l y have f o r e s t s dominated by Pinus f l e x i l i s and Pseudotsuga.
Climatic i n f l u e n c e s
S o u t h - c e n t r a l Montana h a s a c o n t i n e n t a l c l i m a t e , and r e d b e l t i n j u r y i s o f t e n
s e v e r e a t lower t i m b e r l i n e . The v a l l e y s have h i g h b a s e e l e v a t i o n s and a r e t o o c o l d
( s h o r t growing season, f i g u r e 2) f o r any s i g n i f i c a n t amounts o f Pinus ponderosa; howe v e r , f o r e s t s a r e g e n e r a l l y m o i s t e r t h a n t h o s e o f southwestern Montana. Weather r e c o r d s
f o r t h r e e f o r e s t e d s i t e s i n t h i s r e g i o n a r e found i n t a b l e 4 . Average annual p r e c i p i t a t i o n i n t h e s u b a l p i n e f o r e s t s i s g e n e r a l l y 30 t o 45 i n c h e s ( f o o t n o t e 2 ) .
Southeastern Montana
Forest Region
The s o u t h e a s t e r n Montana f o r e s t r e g i o n i n c l u d e s t h e e x t e n s i v e p u r e Pinus ponderosa
f o r e s t s on lowlands and h i l l y t e r r a i n ( m o s t l y 2,800 t o 4,400 f e c t e l e v a t i o n ) i n t h e
n o r t h e r n G r e a t P l a i n s . I t c o v e r s t h e lower Yellowstone R i v e r d r a i n a g e a s f a r upstream
(west) a s Big Timber. The r e g i o n e x t e n d s up t h e M u s s e l s h e l l V a l l e y t o Harlowton and
i t s n o r t h e r n boundary i n c l u d e s t h e n o r t h e r n m o s t p i n e g r o v e s i n t h e v i c i n i t i e s of Roundu p , M i l e s C i t y , and Baker.
Diagnostic forest vegetation
Although Pinus ponderosa i s t h e o n l y f o r e s t t r e e , i t o c c u r s i n r a t h e r d i v e r s e
h a b i t a t t y p e s ( t a b l e 2 ) . The d r i e s t o f t h e s e f o r e s t s i t e s have v e r y open s t a n d s o f
s h o r t t r e e s (35-60 f e e t ) , w i t h g r a s s l a n d undergrowth ( e . g . , Andropogon gerardii and A.
scoparius, Agropyron spicatwn, Bouteloua g r a c i l i s , Carex f i l i f o l i a )
Conversely, m o i s t
n o r t h - f a c i n g s l o p e s have d e n s e s t a n d s o f P. ponderosa (70-95 f e e t t a l l ) , w i t h a l u x u r i a n t s h r u b and h e r b undergrowth i n c l u d i n g many s p e c i e s c h a r a c t e r i s t i c o f t h e mountain
f o r e s t s t o t h e west ( e . g . , Shepherdia camdensis, Arctostaphylos uva-msi, Berberis
repens, Linmea borealis, Arnica c o r d i f o l i a , Dispomon trachycarpwn, PyroZa secunda, and
.
Smilacina s t e l l a t a ) .
The p r e s e n c e o f Linnaea and some o t h e r undergrowth s p e c i e s s t r o n g l y s u g g e s t s t h a t
t h e more m o i s t h a b i t a t s would s u p p o r t Pseudotsuga; however, t h e n e a r e s t seed s o u r c e f o r
t h i s s p e c i e s i s a t l e a s t 70 m i l e s away i n t h e Bighorn Range. T h i s c o n c l u s i o n i s r e i n f o r c e d by t h e f a c t t h a t Pinus ponderosa s t a n d s d e v e l o p i n g on t h e m o i s t e r s i t e s a r e more
h e a v i l y s t o c k e d t h a n i s c h a r a c t e r i s t i c o f P. ponderosa h a b i t a t t y p e s e l s e w h e r e i n t h e
State.
I n a d d i t i o n t o h a v i n g a s h o r t e r growth form t h a n i t s c o u n t e r p a r t west o f t h e Cont i n e n t a l D i v i d e , t h e P. ponderosa ( v a r . scopulorwn, Booth 1950 and L i t t l e 1953) i n s o u t h e a s t e r n Montana h a s a m a j o r i t y o f two- needle f a s c i c l e s . These may be m a n i f e s t a t i o n s
of s u b s t a n t i a l g e n e t i c d i f f e r e n c e s between t h e west s l o p e and Great P l a i n s P. ponderosa.
Two e a s t e r n d e c i d u o u s - f o r e s t s p e c i e s (Fraxinus pennsy Zvanica and Prunus americana)
o c c u r a l o n g s t r e a m s and m o i s t lower n o r t h s l o p e s i n s o u t h e a s t e r n Montana, and two o t h e r
such s p e c i e s (Ulmus americana and Quercus macrocarpa) r e a c h t h e e a s t e r n edge of t h i s
r e g i o n ( L i t t l e 1971, 1 9 7 6 ) . P f i s t e r and o t h e r s (1977) have d i s c u s s e d c o m p o s i t i o n a l
s i m i l a r i t i e s between t h e P. ponderosa f o r e s t s o f s o u t h e a s t e r n Montana and t h o s e of t h e
Black H i l l s o f w e s t e r n South Dakota a s sampled by T h i l e n i u s (1972).
Forest d i s t r i b u t i o n
Approximately 20 p e r c e n t o f s o u t h e a s t e r n Montana s u p p o r t s f o r e s t . T h i s i s a r e g i o n
w i t h o u t prominent mountains, o r mountain f o r e s t s ; t h u s , it d i f f e r s from a l l o t h e r f o r ested regions.
( N o r t h e a s t e r n Montana does n o t have mountains, b u t a l s o i s w i t h o u t G r e a t
P l a i n s Pinus ponderosa f o r e s t . )
L
Most o f t h e remainder o f t h e r e g i o n i s Great P l a i n s g r a s s l a n d (BouteZoua-StipaAgropyron, a c c o r d i n g t o Kuchler 1964). Some o f t h i s g r a s s l a n d h a s widely s c a t t e r e d
p i n e s , and t h u s can be termed a "savanna."
S o u t h e a s t e r n Montana h a s a c o n t i n e n t a l c l i m a t e . Summers a r e l o n g e r , h o t t e r , and
more humid t h a n t h o s e i n t h e mountainous f o r e s t r e g i o n s ( t a b l e 4 and f i g u r e 2 ) . Most
o f t h e annual p r e c i p i t a t i o n ( r a n g i n g up t o about 18 i n c h e s i n m o i s t f o r e s t a r e a s )
comes i n s p r i n g and summer r a i n s . Winters a r e g e n e r a l l y d r y and c o l d , b u t a r e n o t a s
s e v e r e a s t h o s e i n t h e n o r t h e r n p a r t s of Montana e a s t o f t h e C o n t i n e n t a l Divide.
Northeastern Montana
i-1,
The n o r t h e a s t e r n p a r t o f Montana i n c l u d e s t h e a r e a n o r t h o f Miles C i t y and e a s t o f
t h e Missouri River Breaks. P o t e n t i a l n a t u r a l v e g e t a t i o n i s Great P l a i n s g r a s s l a n d
(BouteZoua-Stipa-Agropyron and Agropyron- Stipa, a c c o r d i n g t o Kuchl e r 1964) except f o r
s t a n d s o f PopuZus d e Z t o i d e s l i n i n g t h e p r i n c i p a l r i v e r s . This r e g i o n h a s no upland
f o r e s t , except f o r a few widely s c a t t e r e d p o p u l a t i o n s o f s t u n t e d P i n u s ponderosa.
(The
most n o t a b l e s t a n d i s a t t h e P i n e s R e c r e a t i o n Area s o u t h o f Glasgow on Fort Peck Reserv o i r . ) The extremely c o l d c o n t i n e n t a l w i n t e r s , coupled w i t h d e s i c c a t i n g winds, may be
t h e f a c t o r s p r e v e n t i n g P i n u s ponderosa from growing h e r e . Average annual p r e c i p i t a t i o n
i s between 11 and 1 5 i n c h e s i n t h i s r e g i o n (U.S. Dep. Comm. 1971). Table 4 p r e s e n t s
c l i m a t i c d a t a from Glasgow.
RESEARCH AND MANAGEMENT
APPLICATIONS
The f o r e s t r e g i o n s p r e s e n t e d h e r e were developed t o d e s c r i b e d i s t r i b u t i o n s of
f o r e s t h a b i t a t t y p e s ( P f i s t e r and o t h e r s 1 9 7 7 ) - - i . e . , f o r e s t s i t e s and v e g e t a t i o n i n
mature s t a n d s . The r e g i o n s can a l s o b e used i n d e s c r i b i n g d i s t r i b u t i o n s of i n d i v i d u a l
f o r e s t s p e c i e s o r s e r a 1 f o r e s t communities ( e . g . , Acer gzabrwn-SaZix b r u s h f i e l d s )
The Northern Region o f t h e USDA F o r e s t S e r v i c e r e c e n t l y adopted f o r e s t r e g i o n s a s
"seed t r a n s f e r zones" t o h e l p i n s u r e t h a t n u r s e r y - r a i s e d s e e d l i n g s a r e s e n t t o a
geographic a r e a s i m i l a r t o t h e one where t h e s e e d s were c o l l e c t e d .
.
These f o r e s t r e g i o n s may be u s e f u l a s a b i o l o g i c a l l y based r e g i o n a l s t r a t i f i c a t i o n
f o r f o r e s t r e s e a r c h and f o r e s t management s t u d i e s . For example, i t might be u s e f u l t o
s t r a t i f y p r o d u c t i v i t y e s t i m a t e s ( s i t e index and y i e l d c a p a b i l i t y ) of i n d i v i d u a l h a b i t a t
t y p e s by f o r e s t r e g i o n . S i m i l a r l y , t h e s e f o r e s t r e g i o n s l o g i c a l l y could b e i n c o r p o r a t e d
i n s t u d i e s o f g e n e t i c v a r i a t i o n i n t r e e s p e c i e s and i n t r e e improvement programs.
Responses o f t r e e s and o t h e r v e g e t a t i o n t o management a r e o f t e n s t r a t i f i e d by
h a b i t a t t y p e , b u t it may b e u s e f u l t o a n a l y z e them by f o r e s t r e g i o n a s w e l l . F o r e s t
r e g i o n s o f f e r an a d d i t i o n a l dimension f o r i n t e r p r e t i n g v a r i a t i o n i n f o r e s t v e g e t a t i o n .
F o r e s t managers may f i n d appendix C u s e f u l f o r d e t e r m i n i n g t h e l o c a t i o n of f o r e s t r e g i o n
boundaries.
Arno, Stephen F.
1970. Ecology o f a l p i n e l a r c h ( L a r i x ZyaZZii P a r l , ) i n t h e P a c i f i c Northwest. Ph.D.
Diss., Univ. Mont., Missoula, 264 p .
B a i l e y , R. G .
1976. Ecoregions o f t h e United S t a t e s (map) , USDA For. Serv. , I n t e r m t . Reg. , Ogden,
Utah.
B a i l e y , R. G.
1978. Ecoregions o f t h e United S t a t e s (manual t o accompany map). USDA For. S e r v . ,
I n t e r m t . Reg., Ogden, Utah, 77 p.
Booth, W. E .
1950. F l o r a o f Montana. P a r t I , C o n i f e r s and Monocots. 232 p. Mont. S t a t e Univ.,
Bo z eman.
Booth, W. E . , and J . Wright.
1966. F l o r a o f Montana. P a r t 11. Dicotyledons. 305 p. Mont. S t a t e Univ., Bozeman.
Caprio, J. M.
1965. Average l e n g t h o f f r e e z e - f r e e season. Mont. Agric. Ext. S t n . , Bozeman. F o l d e r
83 (map)
Crowley, J. M.
1972. Environmental r e g i o n s of Montana. I n Montana Environmental Q u a l i t y Council,
F i r s t Annu. Rep., Helena, Mont., p. 2-11.
Daubenmire, R.
1969. S t r u c t u r e and ecology o f c o n i f e r o u s f o r e s t s o f t h e Northern Rocky Mountains.
Proc. 1968 Symp. (Coniferous F o r e s t s o f t h e Northern Rocky Mountains), Univ. Mont.,
Missoula, p . 25-41.
Daubenmire, R . , and J. B. Daubenmire.
1968. F o r e s t v e g e t a t i o n o f e a s t e r n Washington and n o r t h e r n Idaho. Wash. Agric. Exp.
S t n . , Pullman. Tech. B u l l . 60, 104 p.
Goldin, A . , and T. J. Nimlos.
1977. V e g e t a t i o n p a t t e r n s on l i m e s t o n e and a c i d p a r e n t m a t e r i a l s i n t h e Garnet Mount a i n s o f western Montana. Northwest S c i . 51(3):149-160.
Green, A. W . , and T. S e t z e r .
1974. The Rocky Mountain t i m b e r s i t u a t i o n , 1970. USDA For. Serv. Resour. B u l l .
INT-10, 78 p. I n t e r m t . For. and Range Exp. S t n . , Ogden, Utah.
Hitchcock, C. L . , and A. C r o n q u i s t .
1976. F l o r a o f t h e P a c i f i c Northwest. 730 p. Univ. Wash. P r e s s . , S e a t t l e .
Hitchcock, C. L . , A. Cronquist, M. Ownbey, and J . Thompson.
1955-1969. Vascular p l a n t s o f t h e P a c i f i c Northwest (5 v o l s . ) .
Univ. Wash. P r e s s ,
Seattle.
Hutchison, S. B . , and P. D . Kemp.
1952. F o r e s t r e s o u r c e s o f Montana. USDA For. S e r v . , For. Res. Rep. 5 , 76 p. North.
Rocky M t . For. and Range Exp. S t n . , Missoula, Mont.
Kirkwood, J . E .
1922. F o r e s t d i s t r i b u t i o n i n t h e Northern Rocky Mountains. Mont. S t a t e Univ., B u l l .
247 ( s e r . 2 ) , Missoula, 180 p.
Kuchler, A. W.
1964. P o t e n t i a l n a t u r a l v e g e t a t i o n o f t h e conterminous United S t a t e s (map and manual)
Am. Geog. Soc. Spec. Publ. 36, 116 p.
.
I
I
Kuchler, A. W.
1973, Problems i n c l a s s i f y i n g and mapping v e g e t a t i o n f o r e c o l o g i c a l r e g i o n a l i z a t i o n .
Ecology 54:512-523.
L i t t l e , E. L . , Jr.
1953. Check l i s t o f n a t i v e and n a t u r a l i z e d t r e e s o f t h e U.S. USDA For. S e r v . A g r i c .
Handb. 41, 472 p.
L i t t l e , E. L., Jr.
1971. A t l a s o f United S t a t e s t r e e s . Vol. 1. C o n i f e r s and i m p o r t a n t hardwoods. USDA
For. S e r v . Misc. Publ. 1146.
L i t t l e , E . L. J r .
1976. A t l a s o f United S t a t e s t r e e s . Vol. 3. Minor w e s t e r n hardwoods. USDA F o r .
S e r v . Misc. Publ. 1314.
Lynch, D. L.
1955. Ecology o f aspen groveland i n G l a c i e r County, Montana. E c o l . Monogr.
25:321-344.
McWhirter, N . , and R. McWhirter.
1972. Guinness book o f world r e c o r d s . 704 p. S t e r l i n g P u b l . Co., N. Y .
Mueggler, W. F., and W. P. Handl.
[ I n p r o c e s s . ] Mountain g r a s s l a n d and s h r u b l a n d h a b i t a t t y p e s o f w e s t e r n Montana.
USDA For. S e r v . , Gen. Tech. Rep., I n t e r m t . For. and Range Exp. S t n . , Ogden, Utah,
and North. Reg., Missoula, Mont.
Mueller-Dombois, D. , and H. E l l e n b u r g .
1974. Aims and methods o f v e g e t a t i o n ecology. 547 p. John Wiley and Sons, N . Y .
Payne, G. F.
1973. V e g e t a t i v e r a n g e l a n d t y p e s i n Montana. Mont. A g r i c . Exp. S t n . , B u l l . 671.
Bozeman, 1 5 p. and map.
P f i s t e r , R. D . , B. Kovalchik, S. Arno, and R . Presby.
1977. F o r e s t h a b i t a t t y p e s o f Montana. USDA For. S e r v . Gen. Tech. Rep. INT-34.
174 p. I n t e r m t . For. and Range Exp. S t n . , Ogden Utah.
Ross, R. L . , and H. E . Hunter.
1976. Climax v e g e t a t i o n o f Montana based on s o i l s and c l i m a t e . USDA S o i l Cons.
S e r v ., Bozeman. 64 p. and map.
Rowe, J . S.
1959 and 1972 e d i t i o n s . F o r e s t r e g i o n s o f Canada. Canadian F o r e s t r y S e r v . P u b l .
1300. 172 p. Ottawa.
Schmidt, W. C . , and W . P. Dufour.
1975. B u i l d i n g a n a t u r a l a r e a system f o r Montana. Western Wildlands 2 ( 1 ) : 2 0 - 2 9 .
Mont. For. and Cons. Exp. S t n . , Univ. Mont., Missoula.
T h i l e n i u s , J . F.
1972. C l a s s i f i c a t i o n o f d e e r h a b i t a t i n t h e ponderosa p i n e f o r e s t o f t h e Black H i l l s ,
South Dakota. USDA For. S e r v . Res. Pap. RM-91, 23 p. Rocky M t . For. and Range
Exp. S t n . , F o r t C o l l i n s , Colorado.
Thompson, L. S . , and J. K u i j t .
1976. Montane and s u b a l p i n e p l a n t s of t h e Sweetgrass H i l l s , Montana, and t h e i r
r e l a t i o n s h i p t o e a r l y p o s t g l a c i a l environments o f t h e Northern G r e a t P l a i n s .
Canadian F i e l d - N a t u r a l i s t 90(4):432-448.
USDA S o i l C o n s e r v a t i o n S e r v i c e .
1968. Average a n n u a l mountain p r e c i p i t a t i o n (map). S o i l Cons. S e r v . , Bozeman,
Montana.
U . S. Department o f Commerce.
1971. C l i m a t e s o f t h e S t a t e s : Montana. Climatography o f t h e United S t a t e s No. 60:
24. Environ. Data S e r v . , S i l v e r S p r i n g s , MD.
Weaver, T., and D. A. P e r r y .
1978. R e l a t i o n s h i p o f c o v e r t y p e t o a l t i t u d e , a s p e c t , and s u b s t r a t e i n t h e B r i d g e r
Range, Montana. Northwest S c i . 52(3):212-219.
APPENDIX A
Distribution of key tree and undergrowth species in Montana
NORTHWESTERN
Figure A-].--Natural d i s t r i b u t i o n of Tsuga
heterophylla i n Montana.
(Species common i n
suitable habitats within
shaded area. X's indicate small outlying
populations. )
WES
Figure A-2.--Natural d i s t r i b u t i o n of Pinus
monticola i n Montana.
(Species common i n
suitable habitats wlthin
shaded area. X's i n dicate small outlying
populations. )
Figure A-3.--Natural
distribution of
Thuja p l i c a t a in
Montana. (Species
common in suitable
habitats within shuded
area. X's indicate
smaZ l out lying
popu Zations. )
NORTHWESTERN
WES
Figure A-4. --Natural
distribution of Abies
g r a n d i s in Montana.
(Species common in
suitable habitats
within shaded area.
X's indicate small
outlying populations.)
NORTHWESTERN
-
Fiaure
A-5. --Natural d i s t r i "
b u t i o n o f Larix o c c i d e n t a l i s
\ I
I
i n ~ m. t a & . - (Species
-.
common
. -.
i n s u i t a b l e h a b i t a t s wzthzn
I
shaded area. X's i n d i c a t e
*H'/
smal Z o u t l y i n g populations. )
- - . -- . .
CENTRAL
-
-
NORTH- ,CENTRAL
I
\
WES
WES
I
Figure A-6.--Natural d i s t r i b u t i o n of Pinus f l e x i l i s ( p l o t l o c a t i o n s and observations
onZy) i n Montana.
28
-
Figure A-7. --Natural d i s t r i b u t i o n of C l i n t o n i a
u n i f l o r a i n Montana.
(Species comon i n
suitable habitats within
shaded area. X's i n dicate small outlying
populations. )
WES
NORTHWESTERN
Figure A-8. --Natural
d i s t r i b u t i o n of Luzula
h i t c h c o c k i i i n Montana.
(Species comon i n
suitable habitats w i t h i n
shaded area. X's i n dicate small outlying
populations. l
NORTHWESTERN
Figure A-9.--Natural d i s t r i b u t i o n of Menziesia
ferruginea i n Montana.
(Species common i n s u i t a b l e
habitats w i t h i n shaded area.
X's indicate small outlying
populations. )
NORTHWESTERN
WES
Figure A-1 0. --Natural dist r i b u t i o n of Xerophyllum
tenax i n Montana. (Species
common i n s u i t a b l e h a b i t a t s
within shaded area. X's in.dicate small outlying
populations. )
APPENDIX B
Number of sample p l o t s ( P f i s t e r and o t h e r s 1977)
by h a b i t a t type, phase, and f o r e s t region i n Montana
T a b l e B-1--Number o f s q l e p l o t s ( P f i s t e r and others 1 9 7 7 ) by habitat type,
phase, and f o r e s t region i n Montana.
NW
WC
NC
C
SW = southwestern Montana
SC = south-central Montana
SE = southeastern Montana
Northwestern Montana
west-central Montana
north-central Montarxz
= central Montana
=
=
=
S e r i e s / h a b i t a t type/phase
( c . t . = cort~mmityt y p e )
: NW
: WC
Montana f o r e s t r e g i o n
: NC : C : SW : SC
: SE
: Total
Forested scree
Pinus f l e x i l i s s e r i e s
/Agropyron spicatum h . t .
/Festuca idahoensis h . t .
- F e s t u c a i d a h o e n s i s phase
- F e s t u c a s c a b r e l l a phase
/ J u n i p e r u s communis h; t
.
.
.
1
2
2
1
6
1
1
1
4
2
3
1
-
2
2
7
4
1
-
4
-
7
-
1
14
2
3
13
19
13
27
1
6
45
8
5
24
7
P i n u s ponderosa s e r i e s
.
.
/Andropogon spp h . t
/Agropyron spicatum h . t .
/Festuca idahoensis h . t .
- F e s t u c a i d a h o e n s i s phase
- F e s t u c a s c a b r e l l a phase
/Purshia t r i d e n t a t a h . t .
-Agropyron spicatum phase
- F e s t u c a i d a h o e n s i s phase
/Symphoricarpos a l b u s h . t .
-Symphoricarpos a l b u s
phase
- B e r b e r i s r e p e n s phase
/Prunus v i r g i n i a n a h . t .
-Prunus v i r g i n i a n a phase
-Shepherdia c a n a d e n s i s
phase
Pseudotsuga m e n z i e s i i s e r i e s
/Agropyron spicatum h . t .
/Festuca idahoensis h . t .
/Festuca s c a b r e l l a h . t .
/Vaccinium caespitosum h . t .
/Physocarpus malvaceus h . t .
-Physocarpus malvaceus
phase
-Calamagrostis r u b e s c e n s
phase
1
1
5
15
4
1
2
9
12
23
1
7
5
.
i
6
2
3
8
(con. )
Table B-1.--(con.)
Series/habitat ty-pe/phase
:
NW
:
WC
Montana forest region
: NC : C : SW : SC
:
SE
Pseudotsuga menziesii series
/Vaccinium globulare h.t.
-Vaccinium globulare phase
-Arctostaphylos uva-ursi
phase
-Xerophyllum tenax phase
/Linnaea borealis h.t.
-Symphoricarpos albus
phase
-Calamagrostis rubescens
phase
-Vaccinium globulare phase
/Symphoricarpos albus h.t.
-Agropyron spicatum phase
-Calamagrostis rubescens
phase
-Symphoricarpos albus
phase
/Calamagrostis rubescens h.t.
-Agropyron spicatum phase
-Arctostaphylos uva-ursi
phase
-Calamagrostis rubescens
~hase
-Pinus ponderosa phase
/Carex geyeri h.t.
/Spiraea betulifolia h.t.
/Arctostaphylos uva-ursi
h.t.
/Juniperus communis h.t.
/Arnica cordifolia h.t.
/Symphoricarpos oreophilus
Picea series
/Equisetum arvense h.t.
/Clintonia uniflora h.t.
-Vaccinium caespitosum
phase
-Clintonia uniflora phase
/Physocarpus malvaceus h.t.
/Galium triflorum h.t.
/Vaccinium caespitosum h.t.
/Senecio streptanthifolius
h.t.
-Pseudotsuga menziesii
phase
-Picea phase
/Linnaea borealis h.t.
/Smilacina stellata h.t.
3
2
1
1
i
i
9
1
2
5
5
2
-
4
-
2
8
16
.
i
4
i
i
31
1
5
4
19
4
1
10
ti
11
4
31
(con. )
:
Total
Table B-1.--(con.)
Series/habitat type/phase
Montana forest region
: NC : C : SW : SC
: NW
: WC
: SE
: Total
5
1
6
4
2
1
6
6
Abies grandis series
/Xerophyllum tenax h.t.
/Clintonia uniflora h.t.
-Clintonia uniflora phase
-Aralia nudicaulis phase
-Xerophyllum tenax phase
/Linnaea borealis h.t.
-Linnaea borealis phase
-Xerophyllum tenax phase
5
4
4
3
2
5
3
-
3
30
2
1
1
15
9
7
11
42
24
6
Thuja plicata series
/Clintonia uniflora h.t.
-Clintonia uniflora phase 13
-Aralia nudicaulis phase
8
-Menziesia ferruginea phase 6
/Oplopanax horridum h.t.
38
-
4
Tsuga heterophylla series
/Clintonia uniflora h.t.
-Clintonia uniflora phase 27
-Aralia nudicaulis phase 11
38
27
Abies lasiocarpa series
(Lower subalpine h . t . s )
/Oplopanax horridum h.t.
4
/Clintonia uniflora h.t.
-Clintonia uniflora phase 18
-Aralia nudicaulis phase 12
-Vaccinium caespitosum
phase
8
-Xerophyllum tenax phase 13
-Menziesia ferruginea
phase
12
/Galium triflorum h.t.
/Vaccinium caespitosum h.t.
/Calamagrostis canadensis h.t.
-Calamagrostis canadensis
phase
-Galium triflorum phase
-Vaccinium caespitosum
phase
3
/Linnaea borealis h.t.
-Linnaea borealis phase
1
-Xerophyllum tenax phase
5
-Vaccinium scoparium phase 2
/Menziesia ferruginea h.t. 19
.
4
11
4
3
2
32
18
2
7
i
10
21
8
10
2
2
4
i
3
i
8
2
1
1
8
2
1
1
2
4
2
1
i
4
10
8
3
37
5
22
34
10
23
5
6
7
2
i
i
20
13
17
2
1
64
(con. )
Table R-1.--(con.)
Serieslhabitat tvnelnhase
: NW
: WC
Montana forest region
: NC
: C : S1.l " SC
: SE
: 'Total
Abies lasiocarpa series
(Lower subalpine h.t.s)
Tsuga mertensiana/Menziesia
h.t.
8
/Xerophyllum tenax h.t.
-Vaccinium globulare phase 18
-Vaccinium scoparium phase 3
Tsuga mertensiana/Xerophyllum
h.t.
9
/Vaccinium globulare h.t.
/Vaccinium scoparium h.t.
-Calamagrostis rubescens
phase
-Vaccinium scoparium phase 1
-Thalictrum occidentale
phase
/Alnus sinuata h.t.
/Calamagrostis rubescens h.t.
/Clematis pseudoalpina h.t.
.
/Arnica cordifolia h. t.
/Carex geyeri h.t.
-Carex geyeri phase
-Pseudotsuga menziesii
phase
.
2
18
14
10
3
3
1
1
40
21
9
i
5
3
11
21
;1
2
3
3
4
5
5
10
17
1
5
2
2
1
15
4
2
4
6
10
6
i
i
1
1
1
i
7
8
2
1
2
8
15
24
3
1
3
6
3
3
6
15
13
44
(Upper subalpine h.t. s )
/Ribes montigenum h.t.
Abies 1as.-Pinus albic./
Vaccinium scop. h.t.
/Luzula hitchcockii h.t.
-Vaccinium scoparium phase 5
-Menziesia ferruginea
phase
14
Tsuga mertensiana/Luzula h.t.
-Vaccinium scoparium phase 2
-Menziesia ferruginea
2
phase
4
3
18
4
9
1
9
2
29
24
2
2
(Timberline h.t .s)
Pinus albicaulis-Abies
lasiocarpa h . t. s
Larix lyallii-Abies
lasiocarpa h.t.s
Pinus albicaulis h.t.s
4
6
5
29
1
- 168
221
3
4
6
-
i
-
4
-
43
63
2
94
7
30
i
9
-
-
93
36
682
-=->-
(con. )
35
Table R-1.--(con.)
Series/habitat type/phase
-. :
NW
: WC
Montana forest region
: NC : C : SW : S C
: Total
: SE
Pinus contorta series
/Purshia tridentata h.t.
/Vaccinium caespitosum c.t.
.
/Linnaea borealis c.t.
1
/Vaccinium scoparium c.t.
1
/Calamagrostis rubescens c.t.
2
Unclassified stands
Total number of plots
4
3
3
;1
12
17
20
i
il
4
2
6
5
2
1
10
i
-
-
1
14
1
10
6
6
4
21
11
8
3
12
3
6
399
459
66
217
188
178
6
-
58
43
24
1
1,531
This total includes 35 Pinus contorta community type plots also
listed under Pseudotsugo, Picea, or Abies Zasiocarpa habitat types.
APPENDIX C
National F o r e s t s , Indian Reservations, and
National Parks w i t h i n each f o r e s t r e g i o n i n Montana
N a t i o n a l F o r e s t s ( f i g . C - l ) , I n d i a n R e s e r v a t i o n s , and National Parks
w i t h i n each f o r e s t r e g i o n .
(N.F. = N a t i o n a l F o r e s t ; R.D. = Ranger D i s t r i c t ) :
Forest region
Areas incZuded
Northwestern
F l a t h e a d N.F.
Kootenai N.F.
Lolo N . F . (Thompson F a l l s , P l a i n s ,
S u p e r i o r , and W . and N . p o r t i o n s o f
Ninemile R . D . ' s )
Flathead Indian Reservation
G l a c i e r National Park (W. s l o p e )
West - c e n t r a l
B i t t e r r o o t N.F. (Montana p o r t i o n )
Deerlodge N.F. ( P h i l i p s b u r g R . D . , W .
p o r t i o n o f Deer Lodge R.D.)
Helena N . F. (Blackfoot R i v e r d r a i n a g e
p o r t ion)
Lolo N.F. (Missoula, S e e l e y Lake, and
S.E. p o r t i o n o f Ninemile R.D.)
North- central
Lewis and C l a r k N.F. (Rocky Mountain
Front p o r t ion)
Blackfeet Indian Reservation
G l a c i e r National Park ( E . s l o p e )
Central
Helena N . F . ( e x c e p t Blackfoot R . d r a i n a g e )
Lewis and Clark N.F. (except Rocky M t .
Front and Crazy Mts.)
F o r t Belknap (S. p o r t i o n ) and Rocky Boy
Indian Reservation
Chas. M . R u s s e l l N a t i o n a l W i l d l i f e Refuge
(W. p o r t i o n )
Southwest e r n
Beaverhead N.F.
Deerlodge N.F. (except P h i l i p s b u r g and W.
p o r t i o n o f Deer Lodge R.D.'s)
C u s t e r N.F. (Red Lodge R.D.)
G a l l a t i n N.F.
Lewis and Clark N . F . (Crazy Mts. p o r t i o n )
Crow I n d i a n R e s e r v a t i o n (Pryor and Bighorn
Mts. p o r t i o n )
Yellowstone National Park (Montana p o r t i o n )
Southeastern
C u s t e r N.F. (Montana p o r t i o n except Red
Lodge R.D.)
Crow (except Pryor and Bighorn Mts .) and
Northern Cheyenne I n d i a n R e s e r v a t i o n
Northeastern
F o r t Belknap (N. p o r t i o n ) and F o r t Peck
Indian Reservation
Chas. M . R u s s e l l National W i l d l i f e Refuge
(E. p o r t i o n )
39
*LI.S.
G O V E R N M E N T P R I N T I N G O F F I C E : 1979-0-677-019/71
ARNO, STEPHEN F.
1979. F o r e s t regions of Montana. USDA F o r . Serv. Res. Pap.
INT-218, 39 p. Intermt. For. and Range Exp. Stn., Ogden,
Utah 84401.
In this paper, Montanais divided into eight geographic subdivisions
called " forest regions, " based on distributions of t r e e and undergrowth
s p e c i e s and the relationship of these patterns t o climate and topography.
The regions s e r v e a s a geographic r e f e r e n c e f o r describing patterns of
f o r e s t vegetation a c r o s s the State. Data on the distributions of plant
s p e c i e s and habitat types and f o r e s t zonation a r e presented f o r e a c h
region.
KEYWORDS: f o r e s t ecology, f o r e s t classification, plant geography,
Northern Rocky Mountains
ARNO, STEPHEN F.
1979. F o r e s t regions of Montana. USDA For. Serv. Res. Pap.
INT-218, 39 p. Intermt. For. and Range Exp. Stn., Ogden,
Utah 84401.
In this paper, Montana i s divided into eight geographic subdivisions
called " forest regions, " based on distributions of t r e e and undergrowth
s p e c i e s and the relationship of these patterns t o c l i m a t e and topography.
The regions s e r v e a s a geographic r e f e r e n c e f o r describing patterns of
f o r e s t vegetation a c r o s s the State. Data on the distributions of plant
s p e c i e s and habitat types and f o r e s t zonation a r e presented f o r each
region.
KEYWORDS: f o r e s t ecology, f o r e s t classification, plant geography,
Northern Rocky Mountains