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Big Galne I-Iabitat Reseal·ch in Subalpine
Forests in the Central Roc){y Mountains
Glenn L. Crouch 1
Abstract.--Research findings Indicate that subalpine forests similar to those
on the Fraser Experimental Forest provide growing season habitat for deer and
elk, but are unsuitable as winter range because of deep snow. Even in the
growing season, their value as forage producers may be limited by closed canopies. Segments of these forests apparently can also provide year-round habitat
for moose.
The Fraser Experimental Forest is a high elevation (8,800
to 12,800 feet), north-facing alpine and sUbalpine tract of
about 23,000 acres in north-central Colorado. About one-third
of the total acreage is above timberline and the remainder is
tightly forested, with few natural openings (Alexander et a1.
1985). This paper is conce·rned with the subalpine portion of
the Experimental Forest.
Rocky Mountain elk (Cervus eil7phliS nelsoni) and mule
deer (Odocoilells hemionllS hcmionlls) are the major big game
species that seasonally utilize the alpine and subalpine communities on the Fraser Forest. The Forest serves as summer
range for nominal, but huntable, populations of elk and deer
(fig. 1). Both are absent when deep snow hinders their
movement and covers the low-growing understory vegetation
that is virtually the only nonconifer food source available. in
winter. The wintering areas of Fraser elk and deer have not
been identifie.d, but probably are north and west of the
Experime.ntal Forest on the eastern edge of the well-known
l\fiddle Park winter range (Gilbert et a1.1970, Carpenter et a1.
1979; Tiedeman et a1. 1987) (fig. 2).
Black bear (Ursus americanlls) are occasi.onal visitors,
and moose (Alces alces shiras() may have become resident on
the Forest since the.ir reintroduction into Colorado in 1978 and
1979 (Nowlin 1985).2
The newest big game animal on Fraser also is the largest.
In 1978, moose were released into Colorado, near the town of
Rand, about 40 miles north of the Experimental Forest
(Nowlin 1985). During their first year, at least one moose
traveled almost half the distance from the release site to the
Fraser Forest. By 1982, moose were infrequently observed on
the Forest, and soon afterward a year-round popUlation
apparently was established. These moc)se move extensively
through the year, but their major habitat appears to be willowdominated areas adjacent to the. lower reaches of the larger
streams on, and adjacent to, the Experimental Forest (fig. 3).
Although numbers of moose are not known, they are. regularly
seen by workers on Fraser.
VEGETATION
Vegetation on the Forest has not been classified or
mapped, but the Abies lasiocarpa/Vacdnium scoparium habitat type is dominant, and V ..fcoparium is the major understory
species below timbe.rline (Viallmo et a1. 1972, Crouch 1985,
He·ss and Alexander 1986).
Other habitat types present in the A. iasiocarpa series
inc.1ude A. lasiocarpa/Senecio triangularis and A /asiocarpa/
Calamagrostis canadensis. Both produce much understory
vegetation, but are limited to moist sites and occur sparingly
on most of the Forest. .A.. lasiocarpa/Carcxgeyeri is present; but
its acreage also appears to be limited.
Additional habitat types or plant communities identified
include Pinus conforta/V. scoparium, P. contorfalShepherdia
canadensis, andP. colttortalCarexgeyeri. Acreages of the.se are
relatively small.
Infrequent, but potentiaJly important, communities include a few unclassified, nearly pure stands of Populus tremuloides, mid-height Salix spp.-dominated communities along
water courses, a single stand of _4rtemisia sp., and minor
acreages of multispecies grass-forb stringer meadows . .i\J.SO
present, at lower elevations that burned during logging early
in the century, is a 900-acreP. contorta-dominated stand that
contains various proportions of P. tremuloides.
1Research Wildlife Biologist, Rocky Mountain Forest and Range Experiment Station. Headquarters is in Fort Collins, in cooperation with
Colorado State University.
2personal communication, Colorado Division of Wildlife, April 1987.
106
BIG GAME HABITAT RESEARCH
With few exceptions, habitat studies have. been evaluations of the expe.rime.ntal application of various timber
manage.me.nt practices that are designed to enhance water
production for downstream users.
Completed Studies
Fool Creek
Research on big game habi.tat on the Experimental Forest
be.gan in the late 19505 after timber was harvested on the Fool
Creek study are·a (figs. 4 and 5). There, during 1954-56,278
acres of mature timber on 550 acres of commercial forest land
were dearcut in alternate, variable width strips, to increase
streamflow (Alexander et al. 1985). Two years after logging,
more mule deer fecal groups were found on dearcut than on
uncut strips, and production of some plant species was somewhat greater on the dearcut aPeas (Porter 1959). Fecal counts
in 1966, about 10 years later, showed nearly three times more
Figure 3.--Moose tracks In winter on the Fraser Experimental Forest.
deer droppings per acre on dearcut than on uncut strips
(\\Tallmo 1969).
Deer feeding prefere.nces and amounts of forage available to them in the snow-free season were studied in 1970 and
1975, 15 to 20 years after logging. Results showed that deer
fecal counts and forage production were still greater on
dearcut than on uncut strips, but that inherent forage quality
as indexed by crude protein content and digestibility was not
different between the two treatments (Wallmo et al. 1972,
Regelin et ai. 1974, Regelin and \\7allmo 1978).
Figure 1.--Elk In an aspen opening In central Colorado.
Deadhorse Creek
Crouch (1985) monitored vegetation response to a different timber harvest pattern. This study, conducted on a southfacing segment of the 667-acre Deadhorse Creek watershed,
involved a state-of-the-art cutting practice for maximizing
wa.ter production (fig. 6). Here, 12 more or less evenly
spaced, 3-acre cin~ular patches were .dearcut in a 101-acre
segment of the watershed (Troendle 1983). The Deadhorse
site was simila.r to that on the Fool Creek study area, but
Figure 2.--Middle Park; probable winter range for deer and elk from
the Fraser Experimental Forest.
107
understories generally were drier and less productive
(WaJ.lmo et al. 1972, Crouch 1985).
Data were collected over 5 years in five of the twelve 3acre plots to be elearcut, and five uncut controls (figs. 7 and 8).
All of the control and four of the blocks to be elearcut wereA.
lasiocarpa/V. scopan'um habitat types. The remaining harves1
block was a much more mesic A. lasiocarpa/Scnecio triangularis habitat type. By the fifth growing se·ason, plant production
was unchanged on the uncut blocks; but had increased from
225 to 673 pounds per acre on the average blocks, and from 622
to 3,295 pounds per acre on the. moist block (fig. 9).
Crude protein content was ul1changed on uncut plots, but
increased on the average dearcuts after logging.
Over the 5-ye.ar evaluation, there. were no differences in
numbers of elk fecal groups before and after elearcutting:
although numbers increased gradually on the average dearent
sites. Numbers of dee.r droppings, however, increased over the
postlogging period on all blocks. Elk and deer droppings were
both more abundant after dearcutting on the mesic site.
The major response of undel'story production and herbivore activity on the mesic A. lasiocarpa/Senccio trhmgulari.s
Figure 5.--Fool Creek watershed In 1985.
Flgu.'e 6.--Th.'ee-acl'e circular c:learcuts designed to augment
streamflow on the Deadhorse Creek watershed.
Figure 4.--Fool Creek watershed In 1957.
108
Figure 7.--Clearcut block In subalplnethnber 2 years after logging on
the Deadhorse Creek watershed.
Figure 10.--Growlng stock level (GSL) 40,8 years after thinning In
.fI.Il.y,I contorta, Fraser Experimental Forest.
600
••••••••••••••••••..• Thinned
./.................
500
Q)
U
co
Qj
a.
400
////
III
0
r::::
:J
0
:L
........
300
....
Unthinned
200
Before
thinning
Figure 8.--Clearcut block shown In figure 7 In the ninth winter after
logging.
4
5
block suggests that these sites may be prime candidates for
forage enhancement treatments .
.fi.n.us contorta Stocking Control
600
~
500
Qj
a.
Unlogged
III
'0
r::::
5
3
Years after thinning
Figure 11 rDry weight understory plant production (pounds per acre)
before and after thinning to growing stock level (GSL) 4·0 In polesized .fI.nyJ contorta.
700
al
2
400
Cl.
...........................
..' ..'
300
..'
.'
.........................
200~~
______
Before
logging
~
____
~
____
~~
____
~
234
____
~
__
5
Years after logging
Figure 9.--Dry weight understory plant production (pounds per acre)
on uncut and clearcut blocks, Deadhorse Creek watershed.
109
Plant production and related understory compone.nts
were monitored before and after tre.atments to control growing stock levels (GSLs) in 60-year-old P. contorta growing at
the lowest elevations on the Experimental Forest (Crouch
1986) (figs. 10 and 11). Vegetation on most of the area
resembled P. contorta/V. scoparium and P. contorta/Carex
geyeri plant communities as described by Hess and Alexander
(1986) .
Plant production, cover, crude protein content, and digestibility all increased over :5 years at the lower GSLs 40 and
80, and were essentially unchanged on controls and GSL 120
plots.
According to numbers of fecal groups, deer and cattle
preferred the more heavily thinned blocks, but elk exhibited no
prefere;nce among GSL categories.
Figure 12.--Shelterwood harvelt In subalpine thnber In central Colorado.
Figure 14.--Fence line In a Populus trgmuloldes clearcut shows effects of browsing by deer, elk, and cattle.
Ongoing Fraser Studies
5000
Current studies consist maillly of continued monitoring of
effects of the following treatments on vegetative components
and big game activity.
1. Small-block dear cutting in mature A losiocarpa/V.
scopariurn and A. lasiocarpa/Senccio triangularis
habitat types.
4000
~
u
C\l
"Ql
C.
3000
'"c
"C
2. The first entry of a three-step shelterwood harvest
in matureA.lasiocarpa/V. scoparillln habitat types
(figs. 12 and 13).
---Uncut
:J
0
a..
2000
...............
3. Clearcutting in mature P. contorta/V. scOparillnl
and P. contorta/Shepherdia canadensis habitat
types.
1000
4. Clearcutting and partial cutting in a single stand of
pole-sized Populus tremuloides (figs. 14 and 15).
Before
cutting
............
2
3
4
5
Years after clearcutting
Figure 15.--Dry weight understory plant production before and after clearcuttlng In a stand of Populus tremuloldes.
Other Ongoing Studies
rado (fig. 16). On these sites, effects of aspen regeneration
practices, including commercial clearcutting, on vegetative
components and big game activity are being investigated.
Forest Service big game habitat research elsewhere in the
subalpine forests in the central Rocky Mountains is being
conducted in aspen stands at five locations in western ColoUnlogged
Related Prel'ious Research
500
/ / /...../ ..................... Logged
Q)
u
C\l
Q;
c.
Earlier research on deer and elk fe.eding and use of
subalpine habitats has been conducte.d elsewhere in the central Rocky Mountains. Nichols (1957), Harris (1958), and
Boyd (1970) studied elk on summer and winter ranges on the
"'hite River Plateau, about 75 miles west of the Fraser Forest.
More recently, elk and deer diets and habitat use were studie.d
intensively in subalpine habitats in northern Utah, about 300
miles northwest of the Fraser Forest (Collins et a.1. 1978;
Descha.mps et a1. 1979; C:ollins and Urness 1979, 1983).
One hundred miles north of the Experimental Forest in
the subalpine forests of southern Wyoming, a series of studies
determined effects of road building, logging, cattle, grazing,
400
'"
"C
C
:J
0
a..
...................
300
\.........
................
...•.•..•.
200
Before
logging
2
3
4
5
Years after logging
Figure 13.--Dry weight understory plant production before and after
shelterwood harvesting.
110
to support more animals, especially during severe winters,
such as those that periodically occur in the central Rockie.s.
Segments of these forests apparently can also provide yearround habitat for moose, although the permanence of the
population at Fraser has not yet been established.
and other disturbance factors on elk and their habitats ('''ard
1973, 1976; Ward et al. 1973).
Finally, Hobbs and others, working in nearby Rocky
1\lountain National Park, determined the composition and
quality of elk winter and summer ranges (Baker and Hobbs
1982, Hobbs et a1. 1981). Also estimated were elk winter range
carrying capacities based on energy and nitrogen characteristics of the diets (Hobbs et al. 1982).
LITERATURE CITED
Alexander, Robert R.; Troendle, Charles A.; Kaufmann,
1\lerrHl R.; Shepperd, "'ayne D.; Croue.h, Glenn L.;
Watkins, Ross K.1985. The. Fraser Experime.ntal Forest,
Colorado: Research program and published research
1937-1985. Gen. Tech. Rep. RM-118. Fort Collins, CO:
U.S. Department of Agriculture, Forest Service, Rocky
1\lountain Forest and Range Experiment Station. 46 p.
SUMJ\tARY
Subalpine forests similar to those at Fraser provide growing-season habitat for deer and elk but are unsuitable as winter
range, primarily because of deep snow and secondarily because they lack tall- and mid-height shrub understories.
Their value as growing-season habitat also may be limited by
the. closed-canopy stands that dominate these ecosystems
unless opened by fire or management activities.
However, as e.lsewhere, the critical factor regarding
i.mprovement of the capability of subalpine forests to support
more deer and elk is the inability of their off-site winter ranges
Baker, D. L.; Hobbs, N. T. 1982. Composition and quality of
elk summer diets in Colorado. Journal of '''ildlife 1\lanagement 46(3): 694-670. _
Boyd, Raymond J. 1970. Elk of the "'hite River Plate.au,
Colorado. Tech. Bull. 25. Denver, CO: State of Colorado,
Colorado Division of Game., Fish, and Parks. 126 p.
Carpenter, L. H.; om, R. B.; Freddy, D. J.; Sanders, L. E.1979.
Distribution and movements of mule deer in 1\liddle Park,
Colorado. Spec. Rep. No. 46. Colorado Division of Wildlife. 32 p.
Collins, William B.; Urness, PhilipJ .1979. Elk pellet group distributions and rates of deposition in aspen and lodgepole
pine habi.tats. In: Boyce., Mark S.; Hayden-"'ing, Larry D.,
eds. North American elk: ecology, behavior, and manageme·nt: Proceedings of a symposium; 1978 April 3-5; Laramie, "'Y.Laramie, WY: University of Laramie: 140-144.
Collins, William n.; Urness, I'hillp J.; Austin, Dennis D.1978.
Elk diets and activities on different lodgepole pine seg~
ments. Journal of Wildlife Management 42(4): 799-810.
Crouch, Glenn L. 1985. Effects of clearcutting a subalpine
forest in central Colorado on wildlife habitat. Res. Pap.
Rl\f-258. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range
Experiment Station. 12 p.
Crouch, Glenn L. 1986. Effects of thinning pole-sized lodgepole pine on understory vegetation and large herbivore
activity in central Colorado. Res. Pap. RM-268. Fort
Collins, CO: U.S. Department of Agriculture, Forest
Service, Rocky 1\lountain Forest and Ra.nge Experiment
Station. 10 p.
Deschamps, Joseph A.; Urness, Philip J.; Austin, Dennis D.
1979. Summer diets of mule deer from lodgepole pine
habitats. Journal of WildHfe Management 43(1): 154-161.
Gilbert, Paul P.; Wallmo, Olof C.; Gill, R. Bruce. 1970. Effect
of snow depth on mule deer in1\1idd1.e· Park, Colorado.
Journal of Wildlife Management 34(1): 15-23.
Harris, John T. 1958. Analysis of elk winter range, south fork
of the "'hite River, Colorado. Fort Collins, CO: Colorado
State University. 136 p. 1\1.S. thesis.
Figure 16.--Patch clearcut aspen timber' sale on the San Juan National
Forest In southern Colorado.
111
Hess, Karl; Alexander, Robert R. 1986. Forest vegetation of
the Arapaho and Roosevelt National Forests in northcentral Colorado: a habitat type classification. Res. Pap.
RM-266. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky 1\lountain Forest and Range
Experiment Station. 48 p.
Hobbs, N. Thompson; Baker, Dan L.; Ellis, Jame.s E.; Swift,
David M. 1981. Composition and quality of elk winter
diets in Colorado. Journal of 'Vildlife Management 45(1):
156-171.
Hobbs, N. T.; Baker, D. L.; Ellis, J. E.; Swift, D.1\f.; Gree.n, R.
A. 1982. Energy- and nitr9gen-based estimates of elk
winter-range carrying capacity. Journal of 'Vildlife 1\lanagement 46(1): 12-21.
Nichols, Lyman, Jr. 1957. Forage utilization by elk and domestic sheep in the White River National Fore·st. Fort Collins,
CO: Colorado State University. 92 p.1\f.S. thesis.
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of vacant habitat in north-c.entral Colorado. Fort Collins,
CO: Colorado State UniveJsity. 60 p. Ph.D. di.sse.rtation.
Porter, Ke.nneth A. 1959. Effects of subalpine timber cutting
on wildlife in Colorado. Fort Collins, CO: Colorado State
University. 92 p. M.S. thesis.
Regelin, Wayne L.; Wallmo, Olof C. 1978. Duration of deer
forage benefits after clearcut logging of subalpine forest
in Colorado. Res. Note R1\I-356. Fort Collins, CO: U.S.
Department of Agriculture, Fore.st Service, Rocky Mountain Forest and Range Experiment Station. 4 p.
Regelin, Wayne L.; VlaUmo, Olof C.; Nagy, Julius G.; Dietz,
Donald R. 1974. Effect of logging on forage values for
deer in Colorado. Journal of Forestry 72(5): 282-285.
Tiedeman, James A.; Francis, Richard E.; Terwllliger, Charle.s, Jr.; Carpenter, Len H. 1987. Shrub-steppe habitat
types of 1\liddle Park, Colorado. Res. Pap. RM-273. Fort
Collins, CO: U.S. Department of Agriculture, Forest
Service, Rocky Mountain Forest and Range Experime.nt
Station. 20 p.
Troendle., Charles A. 1983. The Deadhorse experiment. A
field verification of the subalpine wate·r balance mode.1.
Res. Note R1\I-425. Fort Collins, CO: U.S. Department of
Agriculture, Forest Service, Rocky 1\fountain Forest and
Range Experiment Station. 7 p.
'''alimo, Olof C. 1969. Re.sponse of deer to alternate-strip
clearcutting of lodgepole pine and spruce-fir timber in
Colorado: Res~ Note RM-141. Fort Collins, CO: U.S.
Department of Agriculture, Forest Service, Rocky Mountain Forest and Range E'"<pe.rime.nt Station. 4 p.
\"alimo, Olof C.; Regelin, Wayne L.; Reichert, Donald W.
1972. Forage use by mule deer relative to logging in
Colorado. Journal of Vlildlife 1\lanagement 36(4): 10251033.
Ward, A. Lorin. 1973. Elk behavior in relation to multiple uses
on the 1\le.dicine Bow National Forest. In: Proceedings of
the 53rd annual conference; 1973 June 11-13; Salt Lake
City, UT. Salt Lake City, UT: 'Ve.ste.rn Association of
State Game and Fish Commissioners: 125-141.
'Vard, A. Lorin. 1976. Elk behavior in relation to timber
harvest operations and traffic on the 1\le.dicine Bow range
in south-central Wyoming. In: Hieb, Susan R., ed. Elklogging roads: Proce.edings of a symposium; 1976 De.cember 16-17; 1\foscow, 10. Moscow, ID: University of Idaho:
32-43.
\\Tard, A. Lorin; Cupal, Jerry J.; Lea, Alfred L.; Oakley,
Charles A.; Wee.ks, Richard V\T. 1973. Elk behal'ior in
relation to cattle grazing, forest recreation, and traffic. In:
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112