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CONTENTS
Introduction
The Montana Department of Fish, Wildlife &
Parks (FWP) has long recognized the importance
of sagebrush/grassland vegetative communities
as wildlife habitat. Efforts to manipulate these
communities concern FWP because of the potential
implications to wildlife.
Some groups believe sagebrush control generally
will have beneficial results for wildlife, even
if the primary reason for a particular program
is to produce more livestock forage. FWP has taken
part in and endorsed programs designed to alter
vegetation for wildlife habitat improvements.
However, FWP takes strong exception to the generalization
by some that mature sagebrush stands are even-aged
monocultures lacking the diversity necessary for
optimum wildlife habitat.
There are a number of questions regarding sagebrush
control that need to be addressed. For example:
(1) Do we need to regulate sagebrush stands to
keep them productive for wildlife? and (2) What
are the short and long-term ecological consequences
of sagebrush eradication practices (particularly
burning) to the entire vegetative community?
In order to address these and other pertinent
questions, FWP has referred to the literature
on the major topics covered by this report.
TO CONTENTS
Sagebrush:
Important Forage and
Cover For Wildlife
Mule
deer fawn hiding under sagebrush canopy. (Photo
by Randy Haight)
 Sagebrush
has been demonstrated to be a critical food source
for several wildlife species during various seasons
of the year, particularly fall, winter and spring.
Cole (1955) found three different species of sagebrush
comprised 93% of the winter diet of antelope in
Montana. Shrubs (primarily sagebrush) are used
almost exclusively by antelope from November through
March and moderately through the other months
(Pyrah 1987). Big sagebrush ranked first in mule
deer diets in the Bridger Mountains of Montana
during December, January and February (Wilkins
1956). During a 7-year period (1982-89), the average
combined utilization for the various sagebrush
species by deer and elk on the Gardiner, Montana,
winter range was 59% for mountain big sage (Artemisia
tridentata ssp. vaseyana),
42% for Wyoming big sage (A. tridentata ssp.
wyomingensis), 32% for basin big sage (A.
tridentata ssp. tridentata), and
16% for black sage (A. nova) (Wambolt 1990).
Rouse (1957) found that three-tip sage (A.
tripartita) received significant use by elk
during severe winters. Sagebrush comprised 62%
of the yearlong diet of adult sage grouse and
essentially 100% of their winter diet in Montana
(Wallestad et al. 1975). Field observations of
the feeding behavior of the Pygmy rabbit (Brachylagus
idahoensis) indicate heavy reliance on
big sagebrush, primarily the seedheads and vegetative
leaders. Published records of Pygmy rabbit food
habits indicate 99% sagebrush in winter and 51%
in summer (Green and Flinders 1980).
Elk Feeding on big sagebrush near Gardiner,
MT. (Photo by Carl Wambolt)
The winter diet of the sagegrouse consists
nearly 100% of sagebrush. (Photo by FWP)
Big sagebrush is a highly nutritious and digestible
food source for big game animals such as mule
deer (Peterson 1984). Although at one time it
was speculated that deer avoid eating big sagebrush
due to the monoterpenoids (volatile oils) contained
in the foliage, research has shown otherwise (Peterson
1984, Bray et al. 1991). A particular variety
of mountain big sagebrush (Hobble Creek) was preferred
by wintering mule deer in Utah over a non-monoterpenoid
shrub, antelope bitterbrush (Purshia tridentata)
(Welch et al. 1992). During winter, big sagebrush
has a higher crude protein level and digestibility
than most other shrubs or grasses. The winter
crude protein level of sagebrush was 12.4% compared
to only 3.7% for dormant grass and 10.6% for the
highly preferred winter shrub, curl-leaf mountain
mahogany (Cercocarpus ledifolius)
(Welch and McArthur 1979). Digestibility of big
sagebrush in winter ranged from 40-60% while bluebunch
wheatgrass ranged from 43-50% (Ward 1971). The
winter digestibility of grass was reported by
the National Academy of Sciences (1964) to be
31%. Data from tests of browse and grass1 species
considering the above factors found only big sagebrush
and curlleaf mountain mahogany meet or exceed
the protein needs of wintering mule deer (Thompson
et al. 1973, Welch et al. 1979).
Mule deer relay heavily on sagebrush for winter
forage in many areas of Montana. (Photo by FWP)
 Sagebrush
also provides cover (nesting, resting and escape)
for a wide variety of game and non-game species
(i.e. protective cover for fawns, calves, nesting
birds, grouse broods, etc.). As an example, Brewer’s
sparrows (Spizella breweri) nest off the
ground in the foliage of big sagebrush plants
(Best 1970). Research in Montana revealed that,
during the breeding season, sage grouse utilize
habitat with a canopy coverage of big sagebrush
ranging from 20-50% (Eng and Schladweiler 1972,
Wallestad 1972, Wallestad and Schladweiler 1974).
Wintering grouse were found in an average of 28%
sagebrush cover (Eng and Schladweiler 1972) and
nesting birds in an average of 20-30% sagebrush
cover (Wallestad and Pyrah 1974). Another species
of special concern is the pygmy rabbit. The pygmy
rabbit is limited to habitat types which contain
tall dense sagebrush (Green 1980a; Green 1980b;
Campbell 1982; Weiss 1984; Lyman 1991).
Brewers sparrow nest in foliage of big sagebrush.
(Photo by FWP)
 Sagebrush
has other assets for wildlife in addition to forage
and cover. Its thick canopy protects understory
vegetation from livestock grazing. Understory
vegetation can be a valuable food source for wildlife.
Additionally, the crowns of sagebrush plants tend
to breakup and weaken hard crusted snow on winter
ranges making it easier for big game to access
understory plants for foraging.
Plant physiologists at the Forest Service Intermountain
Research Station’s Shrub Sciences Laboratory
in Provo, Utah, recognize big sagebrush as important
wildlife food and cover, and are developing the
best varieties for restocking rangelands (Tippets
1992).
TO CONTENTS
Sagebrush
Ecology
Historical Occurrence Of Big Sagebrush
Opinions differ on historic sagebrush distribution.
Jorgensen (1990) reported that a number of researchers
contend big sage has significantly extended its
historical range, often due to livestock grazing
(Stewart et al. 1940, Stoddart 1941, Woodbury
1947, Wright and Wright 1948, Millin 1950, Cooper
1953, Ellison 1954, Anderson 1956, and Morris
et al. 1958). Others believed sagebrush was a
dominant species in many areas of the west prior
to settlement (Wizlizeners 1839, Fremont 1842,
Stansbury 1852, Russell 1902, Passey and Hugie
1962, Cotter 1963, Tisdale et al. 1969, Robertson
1971, Vale 1975, and Johnson 1984).
Vale (1973, 1975) concluded that intermountain
rangelands were generally dominated by big sagebrush.
His research concluded major areas of the intermountain
west were covered by "thick stands of brush"
when the first Europeans arrived. For this reason
he concluded that "attempts to eradicate
brush and encourage pure stands of grass could
not be justified in terms of reestablishing the
natural plant cover."
An observation by Meriwether Lewis, while traveling
in Montana between the Milk and Musselshell Rivers
on May 11, 1805, points to the presence of sagebrush
in Montana before settlement:
the wild hysop [sagebrush] grows here and
in all the country through which we have past
for many days; tho from big Dry river to this
place, it has been more abundant than below,
and a smaller variety of it grows on the hills,
the leaves of which differ considerably, being
more deeply indented near it’s extremity.
The buffaloe deer and elk feed on this herb
in the winter season as they do also on the
small willows of the sandbars (Moulton 1987).
Lewis and Clark made further references regarding
the presence of sagebrush in their journey through
southwestern Montana (i.e. July 22, 1805, near
the present site of Canyon Ferry Reservoir, August
5, 1805, near Twin Bridges (Coues 1965) and August
10, 1805, near the town of Grant (Moulton 1988).
Because sage grouse and sagebrush communities
are inseparable, further evidence of the presettlement
occurrence of this shrub is found by the fact
that the Lewis and Clark expedition members observed
sage grouse along the Marias River north of the
present site of Great Falls (Cutright 1969). Further,
other presettlement explorers killed these birds
along the Milk River in Montana (Coues 1874).
A. J. Noyes (1966), in his book regarding the
early days in the Big Hole Valley of Montana,
commented shortly after the Battle of the Big
Hole in 1877 that the area "...had quite
a lot of high sagebrush..."
Houston (1982) in his book "The Northern
Yellowstone Elk" examined photos of Yellowstone
National Park taken in the 1880s. He states that
early photos clearly show that big sagebrush was
present as a "..dominant overstory shrub..."
Gruell (1983) compared early (1870s) and present
day photos of some areas in Montana. The present
day photos indicated a variety of situations ranging
from increased sagebrush density to a decrease
or stability in other situations. While some would
term the observed increase in shrub densities
as an "invasion" of previously unoccupied
sites, what may be occurring is the reestablishment
of shrubs to formerly occupied sites that were
altered due to a disturbance such as fire. The
fact that big sagebrush was present in a number
of the photos taken in the early 1870s is strong
evidence that big sagebrush was a significant
part of the landscape at the time of white man’s
settlement in Montana. Settlement got its significant
beginnings in Montana in the 1860s, brought on
by the mining camps of gold seekers (Spence 1978).
From that early period to the present day sagebrush
canopy coverage in the area near Bannack, Montana
has remained similar. Big sagebrush cover on the
flats south of the gold mining town of Bannack,
is very similar today to what it was over 130
years ago.
1860's photo near Bannack, MT (Courtesy Bannack
State Park Archives, FWP)
1994 photo near same site at Bannack, MT (Photo
by FWP)
Additional evidence that much of the present-day
sagebrush distribution existed in presettlement
days comes from photographs taken by the Hayden
Expedition in the 1870s in Wyoming, Idaho and
Utah. These were retaken in the 1980s and provide
a picture of landscape change over a 100-year
period (Johnson 1984). Some of Johnson’s
interpretations regarding those photos were:
There was no major shift in sagebrush distribution
as a result of range use. The appearance of
the landscape today is a fair indication of
its appearance in presettlement times. >From
these examples of sagebrush stability, it is
possible to conclude first that big sagebrush
was an important plant dominant of late 19th
century Rocky Mountain rangeland, second that
the shrub represents a genuine climax for these
sites, and third that the use and management
of the past 115 years have not significantly
altered that status.
Johnson (1984) further stated:
There is no basis for assuming that much
of the big sagebrush distribution is a disclimax
or a seral stage toward grassland. The photos
support those who assert overall stability in
sagebrush rangeland.
One of the examples given by Johnson reads as
follows:
Granite Ridges on the Sweetwater (a protected
cove off the Sweetwater River in central Wyoming)
supported a vigorous dominant stand of big sagebrush
in 1870. Today, big sagebrush remains dominant...
Aside from the increase in size and density
of the juniper trees in the rocks, this sandy,
protected site retains, in every way, its appearance
of 1870. Both the sagebrush dominance and the
productive potential of Jackson’s time
[Hayden expedition] remain, indicating a high
degree of site adaptation and ecological stability.
In this last example, it is obvious that fire
was not necessary to maintain the productivity
of the site. The continued presence and increase
in junipers indicated the lack of fire in over
120 years.
TO CONTENTS
Sagebrush
as a "Climax" Species
The final or stable community in a successional
series is the climax community; it is self-perpetuating
and in equilibrium with the physical habitat.
Typically, in an ecosystem, community development
begins with pioneer stages which are replaced
by a series of more mature communities until
a relatively stable community is evolved which
is in equilibrium with the local conditions
(Odum 1959).
In the USDA Bulletin, "Climax Vegetation
of Montana", Ross and Hunter (1976) listed
big sagebrush as one of the species occupying
thousands of acres of rangeland throughout many
areas of Montana.
Mueggler and Stewart (1980), using methods similar
to Daubenmire (1970) and also to Pfister et al.
(1977), developed a classification system for
western Montana rangelands. Sagebrush, and particularly
big sagebrush, was an important climax component
in several of their described habitat types. Many
sites today containing sagebrush in western Montana
can be classified as part of a sagebrush climax
habitat series as described by Mueggler and Stewart
(1980).
Sagebrush is a product of the range. Range ecologist
Gus Hormay (1992) has stated, "The condition
of the soil determines whether or not sagebrush
can grow and persist on a site" . Most plant
ecologists would likely agree with the following
statement by Ross et al. (1976): "soil and
climate are two major factors that determine the
kind and/or amount of climax vegetation."
Big sagebrush is not a foreign invader, but instead,
a naturally occurring native component on many
western rangeland sites. Generally, where sagebrush
is found, it occurs because it is well adapted
to that particular site.
Some have contended that big sagebrush occurs
primarily because of heavy livestock grazing.
This position may have credence in areas where
overgrazed ranges result in soil loss that favor
sagebrush over other plant species. In such cases,
it follows that the new site condition may include
sagebrush as an important and perhaps dominant
species. However, the fact that sagebrush historically
had wide distribution certainly was not related
to heavy use by domestic grazing. Sagebrush was
present when the livestock industry established
in Montana. The livestock industry, which initially
followed in the wake of the miners, became big
business in the 1870s and 80s when grazing on
public lands was free (Spence 1978). In fact,
it could be argued that in some situations heavy
grazing might actually impede the expansion of
sagebrush. A study assessing the effect of livestock
grazing on sagebrush regeneration demonstrated
a high trampling mortality of sagebrush seedlings
(Owens et al. 1992). Some exclosures in Yellowstone
National Park exhibit more sagebrush inside than
out due to heavy ungulate grazing pressure.
Wild ungulate browsing has eliminated sagebrush
from outside this
exclosure in Yellowstone National Park near Gardiner,
MT. (Photo by FWP)
 Sagebrush
is found in undisturbed areas as well as in locations
grazed by livestock. Examples of such areas can
be found in fenced cemeteries and other locations
protected from domestic grazing (e.g. the Cliff
Lake Natural Area where livestock grazing has
not been permitted for over 40 years). This latter
area, within the Artemisia tridentata/Festuca
idahoensis habitat type, contains "scattered,
multi-aged populations of sagebrush [with] abundant
understory of grasses and forbs" (Mueggler
and Stewart 1980). This observation by Mueggler
and Stewart of a productive understory illustrates
that sagebrush communities do not occur
as monocultures. Additionally, had sagebrush not
occurred here in a multi-aged stand (indicating
it was successfully reproducing), Mueggler and
Stewart would not have been able to list that
shrub as a climax dominant species.
Another indication that the occurrence of big
sagebrush is related primarily to the soil, climate
and topography of an area is demonstrated by areas
where the shrub was once controlled, but has since
returned despite the reduction of domestic grazing
pressure. West et al. (1984) recorded that, despite
13 years of protection from grazing, sagebrush
continued to reestablish following control in
west-central Utah. Thirty years after a sagebrush
burn in Idaho, Harniss and Murray (1973) found
that the vegetation returned to essentially pre-burn
conditions even under good range management
(Figs. 1-3 in Appendix I).
Because big sagebrush is often a dominant component
of stable climax communities, efforts to remove
it will set back plant succession: "potential
productivity of the environment is reflected by
the climax vegetation" (Mueggler et al. 1980).
Harniss et al. (1973), reporting on the study
of a 30 year-old sagebrush burn in Idaho, stated:
Vegetation trends through 1966 show the
overwhelmingly dominant role of big sagebrush
on this sagebrush-grass range near Dubois, Idaho.
Almost all important species of shrubs, grasses
and forbs decreased in yield from 1948-66 as
the big sagebrush recovered its dominance after
the burn (Figs. 1-3 in Appendix I).
While plant communities are dynamic, the degree
and speed of change will depend on the successional
stage in which they occur. Plant communities that
have generally stabilized in a climax condition
with the existing soil and climatic conditions
might change, but only very slowly (Odum 1959).
Some mature sagebrush communities that have not
been altered have been shown to remain relatively
stable and unchanged for over 120 years (Johnson
1984). In contrast, those in a subclimax condition
(e.g. following sagebrush control) change much
more rapidly back towards stability (Harniss and
Murray 1973, Bartolome and Heady 1978, West et
al. 1984). Hormay (1992) agreed with those recognizing
the long-term stability of this shrub when he
stated:
Sagebrush will yield to other plants higher
on the successional scale only as the soil develops
to a higher stage. This takes hundreds, if not
thousands, of years....
It is commonly held that competition from big
sagebrush will depress production of herbaceous
understory species. This observation is often
derived from noting the increase in sagebrush
and decrease in grasses that eventually occur
as disturbed or manipulated habitats (i.e. following
burning) make the transition to climax conditions.
However, research has shown that in mature
sagebrush communities, the presence of and even
increase in big sage did not depress grass production.
In Nevada, Robertson (1971) noted increases in
all vegetation in an area rested from livestock
grazing for 30 years. Sagebrush coverage increased
76% while grasses and forbs increased 60%. Anderson
and Holte (1981) found that after 25 years of
no livestock grazing in southeast Idaho, sagebrush
canopy coverage increased 154%. During the same
period, perennial grass cover increased from 0.3%
to 5.8%. In southwestern Montana, Wambolt and
Payne (1986) found increased coverage in both
forbs and grasses during a 18-year study in a
research plot where big sagebrush had not been
controlled.
Healthy herbaceous understory co-inhabiting
a site with big sagebrush. (Photo by FWP)
Allelopathy
Definition: The suppression of
growth of one plant species by another due to the
release of toxic substances (Webster 1983).
Big sagebrush foliage contains chemical properties
capable of producing allelopathic affects (Schlatterer
et al. 1969; McCahon et al. 1973; Kelsey et al.
1978). The allelopathic affects observed under laboratory
conditions include the retardation of plant growth
and prevention of seedling germination.
Native grass species growing under the canopy
of big sagebrush. (Photo by FWP)
 While
allelopathic properties of big sagebrush have been
reported in laboratory situations, the effect of
this phenomena under natural field conditions
has not been demonstrated. Observations made
by Hoffman et al. (1977) illustrate the problem
of applying laboratory results to natural field
situations. They reported: "not all examples
of germination inhibition under laboratory conditions
can be supported by correspondingly favorable observation
in the field." They found the aqueous extracts
of big sagebrush litter inhibited germination of
such species as western wheatgrass (Agropyron
smithii), pellitory (Parietaria pennsylvanica),
spurge (Euphorbia podperae), rough
pennyroyal (Hedeoma hispida), and
yarrow (Achillea millefolium). Yet,
they noted those same species are often abundant
directly under or very near big sagebrush shrubs.
In fact, well-developed grass and forb understories
are commonly associated with big sagebrush stands
on ranges that have proper grazing management practices.
Kelsey and Everett (1992) have conducted extensive
research on the phenomena of allelopathy. They report
that the importance of allelopathy in the ecology
of sagebrush shrublands has not been demonstrated
to date. They concluded that allelopathy "is
probably not the single most important cause of
changes in plant patterns, succession, productivity,
or plant response to management."
Sagebrush and Hydrology
It has been contended that elimination of deep
rooted sagebrush plants will decrease transpiration
and thereby allow more precipitation to reach groundwater.
This, in turn, would increase stream flows. USDA
Forest Service Hydrologist Alden Hibbert (1983)
states:
"Potential for increasing water yield
by type conversion of sagebrush is poor..."
He further noted that "most sites are too
dry to increase water yields in this way; probably
less than one percent of the western rangelands
can be managed for this purpose."
Hibbert (1983) report noted that any stream flow
increases would be small at best and would only
occur where annual precipitation exceeded 16-18
inches. The annual precipitation reported for most
of the rangeland east of the Continental Divide
in Montana falls below these levels (Montana Climatological
Data 1990).
Under the right conditions (deep soils and adequate
precipitation), small water yield increases maybe
Possible. Sturges (1994) conducted a 23-year study
on the effects of sagebrush removal (through spraying)
in Wyoming and reported an approximate 20% increase
(1.08 cm./ .43 inches) in total annual water yield.
Only 35% of the increase came in the form of increased
groundwater flow. Sturges felt that soils would
need to be nearly a meter or more in depth for any
increase to occur. Opposite results were obtained
in Colorado (Lusby 1979) where sagebrush stands
were converted to grasslands by plowing and seeding.
In that project, a 20% decrease in water yield occurred
on the treated sites. This latter site had less
annual precipitation and a shallower soil profile
than the Wyoming site.
Although some groundwater recharge may occur during
periods of heavy spring rains, most recharge occurs
during snowmelt in much of Montana (Brustkern 1990).
Accumulated snow in sagebrush stands would be more
likely to contribute to the water table than "open"
areas with less buildup. Hutchinson (1965) reported
the rate of snow accumulation in a sagebrush stand
in Colorado, where the brush was above the snow
level, was greater than in adjacent grass vegetation.
Hutchinson (1965) observed that during snowmelt:
Depressions formed around individual sagebrush
plants, while the snowpack between plants remained
relatively unchanged. The trapping of snow in
the depressions after spring snowfalls may be
important in terms of water yields.
In Colorado, Hutchinson (1965) observed that:
In April, an important difference in the snowpacks
between cover types was observed. A continuous,
thin ice sheet had developed in grass plots...
In sagebrush, this feature was nonexistent...
The hydrologic importance of the continuous ice
sheets over soil in the grass-covered areas could
be considerable. Since these sheets are impermeable,
meltwater may not enter the soil beneath, but
may run off over the ice as surface flow... Incomplete
soil moisture recharge could result.
Comparison of root structure between big sagebrush
and grass showing both the diffuse and tap rooted
nature of sage. (Photo by FWP)
 Some
researchers have reported reduced infiltration rates
and increased runoff due to burning (Ahlgren et
al. 1960; Salih et al. 1973; Brown et al. 1985).
For example, in a study of burn effects on a Wyoming
big sagebrush community, Brown et al. (1985) found
that infiltration rates were reduced, sediment concentrations
doubled, and runoff increased the first year after
treatment. The effects were even more pronounced
the second year of the study. Such adverse hydrologic
effects were attributed to water repellency induced
at the surface by burning of the organic matter
originating from sagebrush plants. Buckhouse (1985)
noted:
with an increase in bare ground (after a burn) and
the possibility of hydrophobic (lacking affinity
for water) soils, infiltration rates decrease and
the possibility of overland flows increases.
The root system of big sagebrush is characterized
by a deep tap root along with a shallow, diffuse
root system. It has been demonstrated that a phenomena
called "hydraulic lift" occurs with big
sagebrush that will bring deep soil moisture to
the upper surface layers (Richards and Caldwell
1987, Caldwell and Richards 1989). Caldwell and
Richards (1989) observed:
...water absorbed by deep roots in moist soil
moves through the roots, is released in the upper
soil profile at night, and is stored there until
it is reabsorbed by roots the following day.
These Utah researchers showed that this moisture
transported to the upper soil surface provides normally
unavailable moisture for both the diffuse root system
of sagebrush and neighboring plants. They noted
this activity, which facilitates mineral nutrient
uptake and microbial activity, is important in dry
climates.
Contributions of Sagebrush to Its
Community
As earlier mentioned, sagebrush has a significant
diffuse root system near the surface of the ground
as well as a tap root. These roots continually add
to the soil organic material. Hormay (1970) stated:
Approximately one-third of the roots die each
year... A large amount of organic matter gets
into the soil each year this way.
When most other plants (grasses and forbs) have
ceased growing, sagebrush is still active. Daubenmire
(1970) stated:
During this time (grass and forb growth cessation)
Artemisia (sagebrush) is actively drawing
water from the subsoil, photosynthesizing, and
elaborating proteins and other compounds necessary
to develop sizeable inflorescence with pollen
and fruits. But for the activities of this plant,
vegetation activity is virtually suspended, and
all the extremely high energy supply of this season
would be wasted. These plants (sagebrush) are
therefore responsible for more than doubling the
thickness of the soil profile that is actively
involved in mineral cycling, and in creating litter
and humus that is important in the cycling process
as well as in soil moisture relations... Even
though shrub elimination might tend to increase
the depth of grass root penetration, the increase
would represent only a small fraction of the volume
formerly kept active by the shrub alone.
Harniss et al. (1973) stated:
Apparently, sagebrush must also use soil,
water and nutrients that are not utilized or are
not available to these other species, because
maximum vegetation yields result when sagebrush
is present.
Sagebrush forms a protective barrier against heavy
trampling and impedes grazing by livestock, thereby
protecting grasses growing around the base of these
shrubs. Daubenmire (1970) stated:
The protection afforded many grass plants
by dense clumps of shrubs is the sole reason why
any perennial grass remains in much of the depleted
range.
Canopy of big sagebrush protecting grass from
grazing pressure. (Photo by FWP)
Caldwell and Richards (1987 and 1989) as previously
noted, reported the capability of big sagebrush
roots to recycle deep soil moisture to the upper
soil profile where it becomes available for use.
TO CONTENTS
Manipulation
of sagebrush habitat types
Vegetative consequences of burning
sagebrush
Controlled sagebrush burn. (Photo by FWP)
 Total
vegetative (including sagebrush and/or other woody
species) production is greatest in untreated habitats
(Harniss and Murray 1973; McNeal 1984). Mueggler
and Blaisdell (1958) compared sagebrush control
techniques involving burning, rotobeating, spraying
and railing. They found that regardless of treatment,
total vegetative production three years after treatment
was still considerably less than on untreated areas.
Effect on Sagebrush
While the degree of grass and forb production following
manipulation is variable depending on a variety
of factors including the type of burn, time of year,
and the species involved, the consequences of burning
to big sagebrush are predictably negative. Burned
sites were compared with adjacent unburned sites
near Gardiner, Montana, illustrating the reduction
of big sagebrush and total vegetative production
(see Table 1) (McNeal 1984).
|
Table 1. Production comparison of two burned
sites with environmentally paired unburned
sites in 1980 (McNeal 1984).
|
| |
Production (kg/ha)
|
| Location |
Grass
|
Forb
|
Shrub
|
Total
|
| Spring 1980 burn
site |
387
|
479
|
17
|
883
|
| Unburned site |
511
|
191*
|
227*
|
929
|
| Summer 1974 burn
site |
851
|
175
|
38
|
1064
|
| Unburned site |
823
|
143
|
634*
|
1600*
|
|
*P<0.05
|
|
|
|
|
.
The cover value of big sagebrush
will be lost for a number of years following a fire.(Photo
by FWP)
 Most
research indicates that fire will eliminate sagebrush
for at least several years. Wyoming big sage was
reported to have an exceptionally long recovery
period, while mountain big sage has a tendency to
recover more quickly. One researcher reported mountain
sagebrush seed germination is actually stimulated
by fire (Hironaka et al. 1983). However, because
big sagebrush reproduces by seed and not by sprouting,
recovery can be very prolonged on many sites. In
most cases, big sagebrush eventually returns. Hormay
(1992) stated:
Efforts to control sagebrush by cultural means,
such as spraying, burning, chaining and discing
are doomed to failure. Millions of acres have
been treated by these means throughout the West.
Reductions in stands have been achieved but were
short lived. The stands reestablished in a relatively
few years because of soil condition.
In some situations as found in southwest Montana,
sage recovery has been delayed and/or eliminated
when the shrub was replaced by rabbitbrush (Chrysothamnus
spp.) and horsebrush (Tetradymia canescens),
species which sprout following fire (Hammond 1995).
Effect on Herbaceous Vegetation -
General
Although some studies have shown sagebrush removal
to result in an overall increase in total herbaceous
production for a number of years following treatment,
this effect will not be permanent (Fig. 1 in Appendix
I). Thilenius and Brown (1974) found that increased
herbage production following spraying lasted only
ten years. Johnson (1969) found that on a grazed
Wyoming big sagebrush range, benefits of spraying
sagebrush began to decrease within five years after
spraying, and within 14 years there was no production
advantage. Fraas et al. (1992) found total herbaceous
canopy cover did not differ between burned
and unburned sites in an area near Butte, Montana,
eight years after initial treatment.
Effect on Grasses
Grass production increases that may
occur following burning may not always be related
simply to the removal of sagebrush. Daubenmire (1970)
stated:
Where fire is used to eliminate
Artemisia, the stimulation (in grass production)
can be attributed to the fire itself, for a protracted
increase in production can be observed following
steppe fires outside the range of this shrub.
Uresk et al. (1976, 1980), studying
effects of a wildfire on grassland without sagebrush
in Washington, found that burning increased production
of bluebunch wheatgrass by 24% compared with unburned
treatments.
When there are initial increases in
grass production following a disturbance such as fire,
those gains are typically followed by subsequent declines.
These declines in grass production are a natural transition
of the plant community back again toward climax conditions.
Thilenius and Brown (1974) reported in their study:
Declines in production and in the
proportion of graminoids in the herbage did not
appear to be related to re-invasion of sagebrush
as this re-invasion was minimal on all three sites
even after 10 to 11 years.
They found that total average grass
production for all sites ranged from 458 pounds per
acre before treatment to 1263 pounds per acre three
years later. Grass production then declined to an
average of 361 pounds per acre by 11 years post-burn.
This decline occurred despite minimal re-invasion
by sagebrush (big sagebrush canopy coverage changed
from 18% pretreatment to 3% 11 years post-treatment).
Although some species of grasses may
show an increase after burning, others can be harmed.
This difference is demonstrated when reviewing the
effects of an eight year-old controlled burn on a
sagebrush/bitterbrush grassland near Butte, Montana
(Fraas et al. 1992). In this instance, the total
canopy coverage of grasses declined from pre-burn
conditions, while individual species exhibited the
following responses: bluebunch wheatgrass was unchanged,
Kentucky bluegrass (Poa pratensis) increased,
and Idaho fescue (Festuca idahoensis)
declined. In another study, forbs and bluebunch wheatgrass
increased near Gardiner, Montana, while Idaho fescue
and prairie junegrass (Koeleria macrantha)
decreased following a wild fire and a controlled burn
in sagebrush habitat (McNeal 1984).
It is not uncommon for most grasses
to react negatively the first year following a burn
(Figs. 1 & 2 in Appendix I). Increases in grasses
may not appear for a year or more after a burn, if
at all. Jorgensen (unpubl. rep. 1990) compared the
results of over 30 research studies2 on the effects
of fire on vegetation. The most common effect on Idaho
fescue was negative (particularly with fall burns).
The initial reaction (generally a year following
the burn) of Idaho fescue to burning was negative
in 13 cases as foot noted (1, 2, 4, 5, 10,
11, 13-15, 18, 19, 22, 31), neutral in three (15,
23, 25), none were positive. The effect on Idaho fescue
several years after the burn was still negative in
12 (1, 2, 4, 5, 10, 11, 13, 15, 18, 19, 22, 28) of
those cases and neutral in four (48, 51, 52, 70).
Due to the negative reaction of Idaho fescue to burning,
Hironaka et al. (1983) expressed concern that repeated
burns of mountain sage/Idaho fescue habitats could
lead to the opposite effect of the desired result
and lead to a reduction or elimination of the grass
species, giving a greater competitive edge to sagebrush.
The observed effects of fire on bluebunch
wheatgrass were variable. The initial reactions of
bluebunch in the studies reported by Jorgensen (1990)2
were negative in ten cases (2, 4, 5, 10, 12, 17, 19,
22, 26, 30), neutral in two (24, 28), and positive
in one (17). Several years after the initial burns,
three studies (11, 12, 19) demonstrated continued
negative affects on bluebunch, four (2, 10, 24, 28)
showed neutral effects and four (2, 4, 17, 31) reported
positive results. In comparing the above numbered
references for both bluebunch and Idaho fescue, some
report two different findings that resulted from the
same study using two different parameter measurements
such as biomass vs basal area or fall vs spring, etc.
The effect of burning on other grasses
is also explored in the above studies reported by
Jorgensen (1990). An example of differential species
response is demonstrated in Appendix I, Figures 1
and 2.
These studies make a very strong
point that range managers need to proceed with caution
when considering sagebrush burning as a management
tool to increase forage production. Blaisdell et al.
(1982) in the USDA report "Managing Intermountain
Rangelands," commented that:
It is true that forage production
on a fairly recent burn might surpass that on a
similar area in climax condition because of replacement
of sagebrush by perennial grasses and forbs. However,
ranges that are naturally sagebrush grass
climax cannot be entirely freed of sagebrush (by
burning) for an indefinite period. Repeated burning,
especially at close intervals, to maintain such
a subclimax stage would probably result in eventual
impoverishment of the soil and loss of desirable
species.
Effect on Forbs
In the studies reviewed by Jorgensen (1990), he
reported that fire effects on forb density are variable;
when total forb cover does increase following burns,
those gains are generally shorter lived than those
of grasses (Fig. 1 in Appendix I). Some forbs may
flourish following a fire. These species likely
existed at some lower density in the understory
of the original sage community. Biodini et al. (1989)
concluded "fire alone is not a large enough
disturbance to cause drastic changes in forb composition
of northern mixed prairies." Duvall and Linnartz
(1967) found essentially no change in vegetational
composition as a result of fires.
Changes in Nutrient Content of Vegetation
Normally, nutrients contained in vegetation are
released slowly by decomposition of the plant litter.
However, burning immediately releases these stored
nutrients in the form of volatiles or ash. Nitrogen
and sulfur are at least partially volatilized by
combustion and may be lost from the system (Mueggler
1976). Tiedemann et al. (1978) noted that the combustion
losses resulting from a fire in a Douglas-fir forest
for nitrogen, calcium, magnesium, potassium, and
sodium were 38, ll, 15, 35, and 83% respectively
(Grier 1975). Other nutrients such as phosphorus,
potassium, calcium, and magnesium are changed to
water-soluble salts, which are immediately available
for plant growth (Mueggler 1976). After reviewing
the literature regarding the effects of burning,
Ahlgren et al. (1960) reports ".....since productivity
depends on gradual mineralization and utilization
of fallen litter, it would not be reasonable to
expect continued and repeated burning to improve
soil fertility...."
Burning may result in a short-term increase in
grass nutrient levels. Hobbs and Spowart (1984)
demonstrated slight but significantly increased
crude protein in grasses and forbs due to burning.
Van Dyke (1988) in south-central Montana reported
a two year increase in protein levels in grasses
following burning on a sagebrush-grassland elk winter
range. Jourdonnais (1985) found crude protein increases
following burning were similar to those recorded
after cattle grazing on the Sun River elk winter
range. In Jourdonnais’ study, the resulting
increases in crude protein levels from the burn
and grazing treatments were negated by fall when
the plants became desiccated. In Texas, Lay (1957)
found that "burning increased protein content
as much as 42.8% and phosphoric acid content as
much as 77.8% in the species involved, but most
of the benefits disappeared within a year or two."
In their literature review, Ahlgren et al. (1960)
noted that while various studies examining the affect
of fires on soil nutrition have had contradictory
results, they state: "Reports of lower nitrogen
content following burning are frequent."
The aftermath of some fires has caused serious
soil erosion which can add significantly to loss
of nutrients (Helvey et al. 1985). Tiedemann et
al. (1978) reported significant solution losses
of the various soil nutrients following a burn and
concluded ..."the losses may be sufficient
to restrict development of vegetation." A soil
chemist (Dormaar 1992), warned that even the practice
of grain stubble burning can have detrimental effects:
Burning exacerbates the whole process of organic
matter loss from the soil due to wind erosion.
Moreover, substances which are released during
decomposition of straw help maintain a desirable
soil structure.
There has been contention that older sagebrush
plants contain less nutritional value than younger
ones. However no differences were found in levels
of protein between young and old sagebrush plants
collected on the same sites in southwestern Montana
(Table 2).
|
Table 2. Crude protein content of
big sagebrush in young vs mature plants,
in and outside of burned areas in southwest
Montana, 1991.
|
|
Coll.
Date
|
Site
|
Location
|
B.Sage
Ssp.
|
Age
|
Protein
%
|
Comment
|
|
11/90
|
1
|
Robb Cr. WMA
|
vaseyana
|
15
|
9.01
|
Unaltered range
|
|
"
|
1
|
"
|
"
|
2
|
9.64
|
"
|
|
"
|
2
|
"
|
"
|
25
|
8.86
|
"
|
|
"
|
2
|
"
|
"
|
4
|
9.79
|
"
|
|
"
|
3
|
"
|
"
|
20
|
9.56
|
"
|
|
"
|
3
|
"
|
"
|
5
|
8.30
|
"
|
|
12/91
|
5
|
Virginia
|
vaseyana
|
3
|
8.89
|
Inside burn
|
|
"
|
5
|
City Hill
|
"
|
4
|
8.44
|
"
|
|
"
|
5
|
"
|
"
|
6
|
8.12
|
"
|
|
"
|
5
|
"
|
"
|
18
|
8.59
|
Outside burn
|
|
"
|
5
|
"
|
"
|
21
|
9.24
|
"
|
|
Sagebrush samples were mountain
big sage (Artemisia tridentata ssp. vaseyana).
Dry matter protein analysis
was done by the Nutrition Center, Montana State
University, Bozeman, Montana. The sagebrush
burn on site 5 occurred sometime during the
1980s. Collection by Joel Peterson and Mike
Frisina, FWP.
|
The aftermath of a fire can leave soil exposed
to wind and water erosion. (Photo by FWP)
Sagebrush Control and Wildlife
Wildlife professionals for a long time have been
concerned about the effects of sagebrush manipulation
on wildlife (Quimby 1966). The literature provides
documentation of the reduction in sage grouse resulting
from the eradication or significant alteration of
big sagebrush habitats (Higby 1969, Martin 1970,
Peterson 1970, Pyrah 1972). Many of the studies
looked at the results of chemical spraying or plowing
(conversion to crop land).
Sagebrush grassland converted to cropland near
White Sulphur Springs, Montana where a 50% reduction
in big sagebrush resulted in a dramatic decline
in sage grouse numbers (Peterson 1970). (Photo by
Joel Peterson)
 Klebenow
(1972), suggested that fire could be an ideal tool
to achieve a diverse habitat providing for all the
needs of sage grouse. There has been ongoing research
in Idaho evaluating the effects of fire on wildlife
species such as sage grouse (Gates 1983; Moritz
1988; Sime 1991; Fischer et al. 1994; Connelly et
al. 1994). Researchers found that sage grouse and
antelope made use of burn sites to various degrees;
however, there was no evidence that the treatment
resulted in a greater yearlong habitat carrying
capacity for those species. Initial results of pre-
and post-burn studies in the area of the Idaho National
Engineering Laboratory site have not indicated any
improvement in brood rearing areas (Connelly 1991).
Investigations by Fisher et al. (1994) of sage grouse
ecology for 4 years after a 5,800 ha fire in Idaho
which compared burned and unburned habitats found
that "Fire appeared to negatively impact insect
abundance . . . important in sage grouse diets."
They discovered that although a mosaic of burned
and unburned sage was created by the burn, "there
was no positive response of sage grouse to the burned
area." Connelly et al. (1994) studying the
effects of prescribed burning in southeastern Idaho
from 1986-94 (area burned in 1989) found a greater
decline in active sage grouse leks in the burned
treatment than in the unburned (58% vs 35%). Similarly,
the decline in overall grouse attendance at leks
was greater in the burn area than in the control
(66% vs 40%). Overall grouse declines in the entire
study area were considered a result of the drought.
Other studies have shown big game species, such
as elk, are attracted to burned areas (Jourdonnais
1985, Van Dyke et al. 1988). Jourdonnais (1985)
found the affinity of elk to burned areas was similar
to the response they exhibited toward pastures previously
grazed by livestock. He believed this attraction
on winter range was largely due to the removal of
old standing litter because protein levels in the
grasses in all three situations (burn, unburned
and grazed) were similar during most of the elk
foraging period.
Although some nongame species such as meadowlark
(Sturnella neglecta) and horned larks
(Eremophila alpestris) might benefit from
more open grassland habitat generated by sagebrush
removal, other species like the sage thrasher (Oreoscoptes
montanus) and Brewer’s sparrow are more
likely to be harmed. For example, there was a "significant"
reduction in nesting pairs of the Brewer’s
sparrow following a total kill (spray) of sagebrush
near Winnett, Montana (Best 1970). Brewer’s
sparrows nest in the foliage of sagebrush plants.
Similar results occurred in a Wyoming study (Schroeder
et al. 1975). Walcheck (1970) reported total declines
in breeding bird populations in sprayed sagebrush
for Brewer’s and vesper (Pooccetes gramineus)
sparrows. In a Washington Study of bird distribution
in the shrub steppe community, the following conclusion
was made:
". . . of the 17 species shown for which
comparisons were made, seven had a positive relationship
with the cover of big sagebrush, two were inversely
related, and eight were not related. Therefore,
more shrub-steppe species would benefit by preservation
of big sagebrush than by any other policy indicated
by these data." (Dobler 1994).
A previously sprayed site provides no cover
or forage values for wildlife during winter months.
(Photo by FWP)
 Bird
species that were related positively to sagebrush
cover were the sage thrasher (Oreoscoptes montanus),
sage sparrow (Amphispiza belli), Brewer’s
sparrow, loggerhead shrike (Lanius ludovicianus),
brown-headed cowbird (Molothrus ater), and
mourning dove (Zenaida macroura). The two
that were inversely related were the savannah sparrow
(Passerculus sandwichensis) and long-billed
curlew (Numenius americanus). The other eight
showed no r
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