DISCUSSION AND QUALIFICATION OF PLANT RESPONSE
Plant response varies with fire severity, season of
burn, ecological condition at the time of the burn, and management
activities before and after burning [2]. Vigor of surviving Idaho fescue plants is reduced by
high severity
fires because
the root crown's budding zone is confined to a relatively small area at or above the
surface of the ground where it may be exposed to higher temperatures for
prolonged periods [62]. Spring prescribed burns in
a Nevada big sagebrush/grassland were
classified as "hot" and "cool" fires, and cool fires resulted in only a small decrease
in Idaho fescue cover, while hot burns resulted in a significant (p<0.05) decrease that recovered
to prefire
levels in 3 years [162].
Idaho fescue is sensitive to severe burns in late summer
and early fall in eastern Oregon [146]. Such fires favor succession to forbs in Idaho fescue plant associations
[2]. Both
number of plants and basal crown area were severely reduced in Idaho fescue
following an August wildfire on northern California perennial range and remained
reduced 5 years later [66]. A hot June wildfire in a Montana
grassland reduced biomass and cover of Idaho fescue. The damaged clumps
failed to produce much autumn growth, so Idaho fescue cover remained low in the following
spring in favor of forb species. Idaho fescue recovered completely (98% of unburned cover) 3
years after the fire [9]. Spring and late fall burns on sites with good soil moisture and
favorable Idaho fescue root
reserves are thought to injure
plants less [16,309,314]. Britton and others [37]
observed greater plant damage with
late August than mid-October burning; however, they also found that plants watered
immediately before or after
burning had the greatest basal area reduction and produced the least re-growth. They
explained that with increasing water content, thermal conductivity increases,
and therefore the potential for the heat pulse to reach the grass' meristematic
tissue faster and remain at lethal temperatures longer exists when
soils are wet.
Idaho fescue is tolerant of late-season burning
[2,3,308], but again, results are varied. Armour and others [10] saw recovery to preburn levels of Idaho
fescue in 3 years after fall prescribed burning in
Douglas-fir/ninebark (Physocarpus malvaceus) habitat type in Idaho. Britton and Clark [40]
compared early May, mid-June, and mid-October burns in eastern Oregon and found highest mortality
in early May (30%), and no mortality in mid-June or mid-October. Corresponding basal area
reductions were 48% in May, 52% in June, and 34% in October [40]. A comparison of spring and fall burning in
Idaho fescue grassland in Oregon
showed no difference for season of burn [277]. A significant (p<0.05) decrease in Idaho
fescue cover occurred in both seasons, although frequency was not
reduced, and Idaho fescue remained the dominant prairie species [277].
Conversely, Shwecke and Hann [243] observed 25% kill of
Idaho fescue after a spring burn, compared with 40% kill after a fall burn, in a Douglas-fir and
big sagebrush/grass mosaic in western Montana.
There was a similar decrease in basal crown sizes for both burns, but the canopy cover of surviving
fescue (Festuca spp.) plants
almost doubled compared to prefire canopy cover. Sagebrush sites became dominated by fescues
1 year after fire in both cases [243]. Another comparison of spring and fall
burning found that fall burning killed 20% of the Idaho fescue population
and reduced basal area by 23% the 1st year. Spring burning resulted in no significant
change in basal area and only 3.5% mortality. Plants recovered to 90% of their
preburn size by the 2nd year after the fall burn [238]. Idaho fescue is sensitive to burning
in any season in areas where it is at the margins of
its ecological range [27,62,309].
Fire in water-limited environments generally reduces the
productivity of grasses during the 1st postfire growing season [27,74,231,307], and in many cases
reduces productivity of Idaho fescue for several years to come [125]. Defosse and Robberecht
[84]
used a special device to apply similar fire severity levels inside the
meristematic root crown region to several Idaho fescue and bluebunch wheatgrass plants and
followed the treatment with different levels of competition simulated by
removing varying amounts of aboveground biomass of neighboring potential
competitors. Idaho fescue did show
meristematic damage after the fire, but no mortality was observed. Regrowth occurred within 15 days - more rapidly than bluebunch
wheatgrass. Subsequent competition reduced root production and restricted aboveground
productivity by
115% in Idaho fescue, and by 70% for bluebunch wheatgrass. These results suggest
that survival and productivity following fires is related to subsequent soil water
availability. A species with roots concentrated in upper soil layers (e.g., Idaho
fescue) will experience a decline of water availability when compared with a deeper
rooted species (e.g., bluebunch wheatgrass), thus affecting subsequent growth
[84].
This may help explain why many studies show that Idaho fescue is more severely
damaged by fire than bluebunch wheatgrass [2].
Conrad and
Poulton [62] observed that Idaho fescue basal diameter
reduction was less after fire in grazed conditions (27%) than in ungrazed conditions
(40%). Idaho fescue basal area was reduced equally by burning and clipping (an average of
48%) in
May and June in eastern Oregon [39]. Other
treatment-date combinations (late summer and fall) did not significantly
(p<0.05) reduce basal area,
suggesting that it is less susceptible to late-season defoliation than reported previously.
Recovery of Idaho fescue frequency is also a
function of seed production and germination after a fire. Sapsis [238] found
higher numbers of vegetative culms in burned plants compared with unburned
plants. Seed
production of Idaho fescue plants subjected to fall prescribed burning in the sagebrush/grassland
region in Idaho and Oregon was not different from seed production on unburned controls in postfire years 1
and 3, but was greater on a 5-year-old burn [217]. Both severe and lower-severity fire treatments reduce emergence of
Idaho fescue from seed [57]. Warg [294] cites a study
in which seeds of Idaho fescue are exposed to temperatures of 80,
100, 125, and 150 oC for periods of 5, 15, 30, and 60 minutes. Germination was good for
seeds exposed to 80, 100 and 125 oC for
5 minutes, but did not occur beyond that temperature or time period. Clark and others
[59] studied the effects of fire on seed
banks and found the LD 50 for most seeds was between 70 to 85 oC.
In a basin big sagebrush community in east-central Oregon, mean density and basal area of Idaho fescue was significantly greater
on fall-burned plots (P<0.1) than on
spring-burned and control plots. However, Idaho fescue mortality was less on spring- than fall-burned plots,
and Idaho fescue produced more flowering culms on spring-burned compared to
control plots [238]. See the Research Project Summary of this work for more
information on fire effects on Idaho fescue and 60 additional grass, forb, and woody plant species.
On ponderosa pine and Douglas-fir communities in the Blue Mountains
of northeastern Oregon, Idaho fescue cover and frequency in postfire year
4 were higher on prescribed burned sites than on thinned, thinned-and-burned,
or unburned control sites. Idaho fescue was determined to be an indicator
species for burned sites (P≤0.05). For further information
on the effects of thinning and burning treatments on Idaho fescue and
48 other species, see the Research Project Summary of Youngblood and
others' [317] study.
The following other Research Project Summaries also provide information on
prescribed fire use and postfire response of Idaho fescue and other plant
community species:
Idaho fescue is a small bunchgrass that can survive light-severity fires. It is usually harmed by more severe fire [35,52,253,309]. Fires burning at 10- to 25- year intervals have neutral to negative effects on Idaho fescue [2]. Rapid tillering occurs when root crowns are not killed and soil moisture is favorable [145,231]. Plants may re-establish from seed after fire if temperatures are low enough to allow for survival of seed [59,294].
Native ranges and forests in which Idaho fescue occurs have historically been subjected to fires at varying intervals. Native Americans were probably an important ignition source in prehistoric Idaho fescue grasslands [2]. Maintenance of grasslands in the Intermountain West is dependent, in part, on periodic fires to remove dry matter and invading shrubs and trees [9,12,47,49,159,216]. A decrease in or loss of dominant seral species such as Idaho fescue due to fire exclusion has been noted in many areas [113].
FIRE REGIMES:
The following table provides some fire regime intervals for communities in which Idaho fescue occurs. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Fire suppression coupled with grazing pressure has changed the structure of Idaho fescue communities, often by increasing cover of woody species [2,12]. Prescribed burning can be an effective management tool for all types of Idaho fescue communities. Early spring burning is preferred in some cases e.g., [163,243], late season burning in others (e.g., [3,40,238,308]). Beardall and Sylvester [16] recommend burning of big sagebrush/grasslands before or just after the plants have broken dormancy, when root reserves remain high, to improve survival of perennial species. Johnson and Simon [146] suggest that cool, light burns in late winter or early spring, when plant moisture levels are high, help protect root crowns from damage. Similarly, Wright [307] suggests conducting burns when preferred plants are dormant, and includes that it is better to burn during wet years and never during extended dry periods, so as to not magnify drought stress on plants.
Bunting and others [45] concluded that postfire plant mortality and productivity might be related to the length of time grazing is excluded during postfire regeneration period. Early spring fire alone resulted in low mortality, and early season defoliation (simulated grazing) after fire resulted in 50 % mortality for Idaho fescue. Detrimental effects were lessened when defoliation was delayed by 1 growing season after fire [45]. In a big sagebrush/grassland in Idaho burned once in September of 1933, again in August of 1936, and subsequently "conservatively" grazed after 1 full year of protection, Blaisdell [27] observed no significant differences in total grass production on any severity of burn 15 years after burning. Idaho fescue was, however, significantly reduced, achieving prefire levels within 12 years after a light-severity burn, and at only 77 and 53% of prefire levels 12 years after a moderate and heavy burn, respectively. All other grasses had recovered beyond prefire levels by postfire year [27].
Idaho fescue grows on many landforms, elevations, aspects, and soil types. It occurs at elevations from 990 feet (300 m) in Oregon to nearly 13,200 feet (4000 m) in Colorado [261]. It thrives in areas of 15 inches (380 mm) mean annual precipitation or greater [295], but is also found in areas with lower precipitation (7.3 inches (186 mm) at 1 site in Oregon). Idaho fescue has broad ecological amplitude and a wide range of productivity within and between habitat types in which it is a dominant species [205]. Because of its ubiquity, site characteristics are difficult to generalize. For example, Stubbendieck and others [261] report that Idaho fescue is most abundant on well-drained loams with a neutral to slightly alkaline pH, while other authors [73,130,140,223] report that it favors a slightly acid pH. In the northern Rocky Mountain region it is considered a species of the dry end of the moisture gradient, and in the southern Rockies it is a species of the moist end [75]. Since Idaho fescue occurs in a variety of ecosystems (grassland, sagebrush, forest, and alpine), it is probably most useful to look at site characteristics within each of these ecosystems.
In the grasslands of the Intermountain region, Idaho fescue occurs in valleys, canyons, benches, slopes, and rolling hills bordering sagebrush/grasslands, juniper woodlands, or the lower treeline [36,77,117,187,219]. It is most commonly found in mesic grasslands, but is also a component of the more xeric grasslands dominated by bluebunch wheatgrass, where it usually occupies the cooler, moister microsites on north and east aspects [88,117,159,271]. It can be found on south-facing slopes at higher elevations [120]. It is found on a variety of parent materials and soil depths, but is most productive on well-drained, loamy to sandy soils [120,205]. In a western Montana grassland on morainal mounds in the upper Blackfoot Valley, Idaho fescue tolerated the widest extremes of environmental conditions present, though it did show a gradual decrease on south and southwest exposures of the mounds [31]. In the biscuit scablands (areas of rolling topography on basic flow lavas with "biscuits" of soil between islands of very shallow soil over lava) in eastern Oregon, Idaho fescue grows in the cool moist microsites of the biscuits [120,315].
In semi-arid sagebrush (Artemisia spp.) grasslands, Idaho fescue is found with bluebunch wheatgrass but is restricted to the cooler, moister sites [5,28,46,71,92,93,120,313,316], and tends to be found on deeper, well-drained, loamy to sandy textured soils [25,26,71,122,237]. Idaho fescue occurs as a dominant or co-dominant species on cool, moist microsites protected from wind, where there is more snow retention and less moisture loss than on less protected sites [73,294]. In a study of soil properties in big and low sagebrush (Artemisia arbuscula) communities in southern Idaho, Fosberg and Hironaka [105] concluded that moisture availability was more important than parent material in determining the distribution of bluebunch wheatgrass and Idaho fescue. When compared with 5 common grasses in the Great Basin (bluebunch wheatgrass, Thurber needlegrass, needle-and-thread grass (Hesperostipa comata), galleta (Pleuraphis jamesii), and Indian ricegrass (Achnatherum hymenoides), Idaho fescue and bluebunch wheatgrass were associated with soils in wetter and colder climates and with a slightly more acidic pH, higher water-holding capacity, higher clay contents, and lower bulk density than soils of other grasses. Idaho fescue had the narrowest environmental tolerances [223]. Johnson [144] says that moisture availability (which is enhanced by deeper soils and cooler microsites) determines the ability of Idaho fescue to persist at lower elevations.
Everett [103] examined the possibility of allelopathic effects of singleleaf pinyon and Utah juniper litter on seedling emergence of Idaho fescue, and found that the presence of litter can be a negative factor if seed is buried. Where Idaho fescue occurs in forest habitats with limber pine, ponderosa pine, and Douglas-fir, it is usually on the cool, dry aspects that border sagebrush-grass communities [120,186,221,256].
In the northern Rocky Mountains, Idaho fescue also occurs in mountain parks at upper elevations where tree growth is inhibited [77,79,170,193,216,225,235]. Daubenmire [75,80] speculates that the occurrence of these small parks in northern Idaho and eastern Washington represents areas of soil drought that may have resulted from the transfer of snow from the windward to the leeward slopes. Jensen [143] cites Idaho fescue as 1 of the major grasses at 4,950-9,900 feet (1500-3000 m) on Caribou National Forest, southeastern Idaho. On these sites, moisture becomes limiting soon after snowpack melts, producing drought conditions that dominate through most summer months on predominantly cold, cryic soils. Weaver and Collins [297] found Idaho fescue decreased in abundance with increasing snowpack in Montana. Several authors [21,63,85,120,141,220,225,245] have described alpine and subalpine communities with Idaho fescue as an important, sometimes dominant, component in several western states. Idaho fescue is the dominant understory species on many of the most arid whitebark pine sites [13,256].
Mollisols are most commonly associated with grassland ecosystems; however, Nimlos and Tomer [211] found Mollisols under dry end Douglas-fir forests in southwest Montana, usually on sites where Idaho fescue is among the understory grass component. These sites may have been grasslands that were invaded by conifers. Similarly, the absence of Idaho fescue on unproductive Mollisols may indicate a disclimax where Idaho fescue has been eliminated by disturbance.
Idaho fescue occurs in the following elevational ranges:
MT 5,000-8,000 feet (1500-2400 m) [205,282] UT and CO 7,000-10,000 feet (2100-3000 m) [281,282] CA 3,000-7,000 feet (900-2100 m) [282] ID 1,320-7,000 feet (400-2100 m) [130,271] OR and WA 1,700-8,200 feet (510-2460 m) [71,88,120] WY 5,500-10,000 feet (1650-3000 m) [86,141] AB, BC, SK 4,224-5,148 feet (1280-1560 m) [36,260]Idaho fescue provides important forge for many types of domestic livestock and several wildlife species. In Oregon, Idaho fescue is the main grass selected most seasons by cattle and horses [289] and by elk and sheep in spring [144]. Idaho fescue makes up 29% of cattle diets from June to October, it had more green leaves in summer than did other grasses, and it was sought out for regrowth in the late summer and fall [136]. It is valuable domestic sheep forage on many high-altitude range sites in eastern Idaho [101], and excellent forage in grassland and open ponderosa pine summer cattle ranges of western Colorado [218]. The ponderosa pine/Idaho fescue community is well suited for spring and fall grazing in the Similkameen Valley of British Columbia [185]. Idaho fescue is major livestock forage species in western Montana [205,302], and is generally preferred over its codominant, bluebunch wheatgrass [251]. The foliage cures well and is preferred by livestock in late fall and winter [246].
Idaho fescue is an important component in elk diets throughout the Rocky Mountain region [24,91,161,167,246,269]. The Idaho fescue-bluebunch wheatgrass habitat type in southwestern Montana is widely used by big game animals. Elk and deer use the type as low-elevation winter range, and pronghorn use it year-round. At intermediate elevations Idaho fescue is important spring-fall range, and at upper elevations it provides summer range for elk and mule deer [205]. Some researchers report moderate to heavy use of Idaho fescue as forage for deer [161,215,249,274,285,289]. Others indicate that Idaho fescue plant associations are important deer habitat, but that Idaho fescue is not a preferred forage species [51,83,166]. Bodurtha and others [32] report that Idaho fescue communities are among the least used by mule deer in eastern Oregon. Idaho fescue is a common grass on pronghorn summer range in Yellowstone National Park [244] and southeast Oregon [273] and is reported to be good forage for pronghorn, cattle and sheep in ranges of northern Nevada [116].
Climax bunchgrass communities are dominant components of winter ranges of bighorn sheep, and bunchgrasses are the dominant forage class during the winter [228]. Some Idaho fescue sites at moderately high elevations are used by bighorn sheep and Rocky Mountain goats (Oreamnos americana missoulae) as winter range [154,205,257]; however, Idaho fescue is not commonly used by bighorn sheep in Glacier National Park, Montana [229]. Idaho fescue was an identified component in the stomach of Rocky Mountain goats in the fall in Montana [239], and in Olympic National Park, Washington, it was a selected forage species of mountain goats. It decreased in cover under high mountain goat density, while the less palatable western yarrow (Achillea millefolium) increased in cover [241].
Northern pocket gophers eat primarily the leaves and stems of Idaho fescue in June through September, although they prefer forbs [293]. Cox [68] found that grasses constituted only 2.4% of the shoot matter in northern pocket gopher diets. Idaho fescue was most commonly consumed grass in their diet, probably because it was the most abundant grass on the study site.
Idaho fescue is a component of grizzly bear habitat in Yellowstone National Park [29,30,86] and other locations [98,188,236]. Davis and Butterfield [82] also include it among foods of the grizzly bear. Idaho fescue is a common understory component of grouse habitat in Oregon [69], Idaho [157,208] and Montana [178,179,180,263].
Idaho fescue is a climax indicator or dominant species in
numerous habitat types of grassland, sagebrush, forest, alpine, and riparian
ecosystems. A selection of published classifications naming it as a codominant
species in habitat types, community types or plant associations and
representing its range of occurrence is listed below:
Forest vegetation on National Forests in the Rocky Mountain and
Intermountain Regions: habitat types and community types [4]
Plant community classification for alpine vegetation on the Beaverhead National
Forest, Montana [63]
Forest habitat types of northern Idaho: a second approximation [64]
Steppe vegetation of Washington [76]
Vegetational zonation in the Rocky Mountains [77]
Forest vegetation of eastern Washington and northern Idaho [78]
Yellowstone vegetation: Consequences of environment and history in a natural
setting [86]
Plant communities and habitat types in the Lava Beds National Monument,
California [102]
The vegetation of the Grand River/Cedar River, Sioux, and Ashland Districts of
the Custer National Forest: a habitat type classification [122]
Classification and management of Montana's riparian and wetland sites [123]
Sagebrush-grass habitat types of southern Idaho [130]
Forest vegetation of the Bighorn Mountains, Wyoming: a habitat type
classification [135]
Plant associations of the Crooked River National Grassland [138]
Riparian reference area in Idaho: a catalog of plant associations and
conservation sites [142]
Plant associations of the Wallowa-Snake Province: Wallowa-Whitman National
Forest [146]
Forest vegetation of the Gunnison and parts of the Uncompahgre National
Forests: a preliminary habitat classification [158]
Coniferous forest habitat types of northern Utah [182]
Plant communities of the Similkameen Valley, British Columbia, and their
relationships to soils [186]
Grassland and shrubland habitat types of western Montana [205]
Forest habitat types of Montana [221]
Forest habitat types of central Idaho [256]
Shrub-steppe habitat types of Middle Park, Colorado [270]
Canyon grasslands and associated shrublands of West-central Idaho and adjacent
areas [271]
Grassland and shrubland habitat types on the Shoshone National Forest [278]
A management-oriented classification of pinyon-juniper woodlands of the Great
Basin [300]
Idaho fescue is classified as a codominant with the following species:
Grazing can stimulate plant vitality and play a beneficial role in community
stability; the key is timely grazing of plants and moderate use of the
community [144]. The amount of use that Idaho fescue can sustain
without adversely affecting vigor is dependent on numerous conditions
including the combination of livestock and wildlife using the range, plant
phenology, the
type of grazing system used, competition from
associated vegetation, plant vigor at the time of use, and site conditions
[205]. Mueggler [204] found maximum
leaf length was a good indicator of vigor in Idaho fescue, but noted that
because of yearly variations in weather conditions, evaluation of vigor requires comparison with protected plants of normal
vigor. Many approaches to determining vigor for
Idaho
fescue have been used, sometimes with contradictory results. Mueggler
and
Stewart [205] concluded that the only reliable approach was to observe the response of
the vegetation over a period of years.
Idaho fescue is a decreaser under heavy grazing by livestock
[95,96,141,301] and wildlife [107]. Several studies have
reported Idaho fescue as less abundant on areas grazed by livestock compared to ungrazed areas
[96,141,185,291,294,310]. Olson and Wallander [213]
found root and shoot biomass were 38 and 27% less on grazed than on
ungrazed plants, while carbohydrate pools were similar for grazed and ungrazed
plants. In contrast, spotted knapweed biomass was unchanged by
grazing;
suggesting that repeated grazing may reduce the ability of Idaho fescue to
compete with invading spotted knapweed when both species are grazed [213]. Merrill and others
[191] found that at
the end of the growing season, standing dead material on Idaho fescue plants was less in cattle-grazed
sites than on ungrazed sites; however, standing Idaho fescue biomass and crown biomass were equal
on grazed and
ungrazed sites. In an exclosure study including Idaho fescue sites in Wyoming and Montana, Stohlgren and others [259] report that Idaho fescue showed
inconsistent responses to grazing. Other studies show similar, equivocal
responses [199,304,305]. In northwest Wyoming, Jones [149] found
Idaho fescue decreased under cattle
grazing but remained relatively unchanged by elk grazing.
In Yellowstone National Park, Coughenour and others [65] found no differences in
Idaho fescue cover in exclosed and unexclosed range. Also in Yellowstone
National Park, vegetative culms of Idaho fescue were shorter on areas grazed by elk and bison than culms on
ungrazed areas. Grazing did not affect the number of
vegetative culms or the height or number of reproductive culms of grasses
[250]. Dead bunchgrass clumps (expected on an overgrazed range) did not vary between grazed
and ungrazed sites. Grass biomass was lower on grazed sites in 1986, the drier
year, but not different in 1987 [250].
Northern pocket gopher activity can aggravate impacts of
grazing livestock and can prevent
the return of Idaho fescue on overgrazed ranges [264,265]. Idaho fescue decreases as
northern pocket gopher activity increases
[301], and can give way to Bromus and other undesirable species [185,310]. The dense
roots of Idaho fescue are not preferred forage of northern pocket gophers. They
may protect other plants growing among them
[252], preventing
occupation by northern pocket gophers where turf is intact [265].
Anderson and Scherzinger [7] report
improvement of range for elk with cattle grazing through a detailed resource
management system.
Preconditioning in this manner has been reported to extend the grazing season and improve
production of viable seed in Idaho fescue [6]. Anderson and others [6] measured a 38% increase in
Idaho fescue cover after
grazing by elk for 24 years, thereby re-establishing habitat for blue grouse. Late-seral grasslands dominated by
Idaho fescue may provide the best forage for grass-eating ruminants, but mid-seral
stages of Idaho fescue associations may offer more to all users of grasslands due to their
greater plant species diversity [144].
Bunchgrasses best
tolerate
light grazing after seed formation [43,195]. Britton and others [38] observed the effects of harvest date on
basal area of 5 bunchgrasses in eastern Oregon, including Idaho fescue, and found
grazing from August to October (after seed set) has the least impact on these
bunchgrasses, while plants
harvested in May showed a 40% reduction in basal area, due primarily to
reductions in Idaho fescue
and Thurber needlegrass (Achnatherum thurberianum). Idaho fescue is most sensitive to defoliation from
flowering to seed ripening [144,195,202]. Johnson and Simon [146] suggest avoiding early grazing
that will deter seed
formation. Johnston and others [148] discusses "dates of readiness
for grazing" for fescue grassland, using seed set as an important
indicator. Beetle [20] found Idaho fescue could withstand moderate,
continuous grazing on sedimentary soils, but even light grazing reduced its vigor
on granitic soils [205]. The greatest modification of Idaho fescue communities
in the Blue Mountains of Oregon occurs
with several consecutive seasons
of early spring grazing, when soils are often wet and trampling can dislodge
plants [145].
Abundant information exists on different grazing systems
and management approaches for Idaho
fescue grasslands [90,95,165,205,276,311]. Idaho fescue is favored by light to moderate grazing [72,108,246] and is moderately
resistant to trampling [60,246]. Heavy grazing may lead
to replacement of Idaho fescue with alien species such as cheatgrass [43,207,246], and can adversely affect soil fertility [147].
Control of associated woody species tends to improve
yield and diversity of Idaho fescue communities [50,94,194,196,200,207,262]. Mueggler [203] found
reducing competition
through tilling and clipping more than offset the effects of even extreme
clipping (100% herbage removal at flowering) on the volume of herbage and number
of flowerstalks produced the following year in Idaho fescue plants. Overstory
removal in ponderosa pine and Douglas-fir communities leads to an increase
in yield and abundance of Idaho
fescue [184,197]. Three summers of domestic sheep
grazing to reduce spotted knapweed led to an increase in Idaho fescue plant
density, although leaves and flowerstems on these plants were shorter than in
ungrazed areas [214].
At the edge of its ecological range (e.g., where it
occurs with Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis)
in Oregon), Idaho fescue may be very sensitive
to heavy livestock utilization [88]. The big sagebrush
ecosystem is particularly sensitive to grazing, and bunchgrasses decrease rapidly
with severe defoliation [100]. Mueggler [204] studied the recovery rate of Idaho
fescue and bluebunch wheatgrass after heavy and extreme clipping and found that
Idaho fescue plants of moderately low vigor required about 3 years of protection
to recover normal vigor. He estimated that recovery from a state of low
vigor might take more than 6 years of protection.
Two cultivars of Idaho fescue have been developed that are adapted to variable climatic and soil
conditions in the Intermountain west and Pacific Northwest where precipitation ranges
from 14-31 inches (350-770 mm). They are cold and drought hardy, moderately shade tolerant, grow well
in ponderosa pine/big sagebrush, and persist on shallow, gravelly
to well-drained soils [101].
Nutritional value of Idaho fescue varies with season [17,18,23,128,218,246,251], associated vegetation [128], grazing pressure [250], soil parent material, and soil condition. It is comparable
(mean value) to other native
grass species in the early season but is less digestible than other grasses at
the end of the season [23]. Protein and phosphorus
contents tend to be high in the spring and decrease over the growing season
[17,128,218,246], while calcium remains about the same over the
growing season [218]. Bezeau and
Johnston [23] observed in-vitro digestibility of cellulose in cows and calculated
digestibility of protein in 32 plants species of the rough fescue association.
They found that the nutritional value of Idaho fescue was greatest in the
early season, during the leaf and heading stages, and decreased over subsequent
stages of seasonal growth. Bedell [18] reports similar
seasonal trends in Idaho fescue for crude protein, digestibility, and dry matter. Skovlin
[251] recorded the same trend in crude protein and
phosphorus, with a rise in protein content at the end of the growing season.
Other researchers report that the protein content of Idaho fescue remains higher
than associated grasses during the latter part of the growing season [17,128,251]. Hickman [128] found
crude protein was high in early spring
and deficient during seed formation, with ash content
increasing as protein decreased. Fat content was lower than that of the other grasses
sampled. Digestibility was low in early spring, peaked in May, and was still higher
than other species in the fall [128]. Elliot and Flinders [99] found Idaho fescue had the
highest average crude
protein content and comparable calcium, phosphorus, and moisture content compared
to bluebunch wheatgrass and alpine timothy (Phleum alpinum) in
a wilderness mountain meadow in Idaho.
Nutritive values for Idaho fescue were highest for plants growing in
antelope bitterbrush habitat types
when compared with samples taken from ponderosa pine and western juniper habitat
types on Oregon winter range [128]. In Yellowstone National Park, protein content, nitrogen, macronutrient (Ca, Mg, P, K)
concentrations, and digestibility were higher in Idaho fescue plants grazed by elk in
the winter than in ungrazed plants [250].
Palatability of Idaho fescue varies with season [295] and community type [120]. Bedell and Bunch
[19] report that Idaho fescue is often left ungrazed under a
western juniper canopy but
is readily grazed when the canopy is removed.
Palatability of Idaho fescue is rated as follows [87]:
CO
MT
UT
WY
Mueggler [206] compared dates of phenological events for prominent grasses at 7,100 feet (2130 m) on southwestern and northeastern exposures in western Montana over 10 years. The start of growth was uncertain because green leaves were frequently present at the time of snowmelt, probably because they overwintered from fall regrowth. The following dates were recorded for phenology of Idaho fescue on southwestern exposures [206]:
Event Date range Mean date Growth starts late April to mid-May May 4 1st bloom occurs late May to late June June 14 Blooming over early to mid-July July 13 Dissemination starts late July to mid-August August 5 Plant dried late August to mid October September 21Most studies show that fire initially reduces frequency [48,162,243] and basal area [16,243] of Idaho fescue. Recovery to prefire levels may require more than 25 years if density is severely reduced [15], as was observed by Harniss and Murray [125] in Idaho, where return to prefire cover took over 30 years after summer prescribed burning in a big sagebrush/Idaho fescue range. Effects of most fires are not, however, so extreme, and show a wide range of responses. Idaho fescue plants burned in Nevada in the spring of 1973 still showed signs of damage in 1976, but they were recovering [16]. Idaho fescue frequency was not significantly (p<0.05) different between burn and control plots 2 and 4 years after prescribed burning on a mountain big sagebrush/Idaho fescue site in Idaho [175]. On a lodgepole pine site in Idaho, Idaho fescue plants had regained vigor by the 3rd year and showed improved vigor by the 5th year [222]. Idaho fescue resprouted after spring prescribed burns in central Oregon, and within 3 months more than 80% of Idaho fescue plants had vigorous growth, with greater production in burned areas than in adjacent unburned areas [1]. Forage biomass of burned Idaho fescue grassland had surpassed that of unburned grassland following fires in Yellowstone National Park in both grazed (by elk and some bison) and ungrazed portions, 2 years after burning [248].
Idaho fescue on burned areas may have more protein than those on unburned areas [16]. Singer and Harter [248] found that digestibility of Idaho fescue was enhanced (for 1 year) on grazed but not on ungrazed sites following the 1988 fires in Yellowstone National Park. Dry matter digestibility was higher in Idaho fescue plants the 1st year following burning in Yellowstone, and both digestibility and percent protein were higher the 2nd year [212]. Similarly, crude protein in Idaho fescue increased from 0.6 to 2.6% after spring burning in Douglas-fir and limber pine in central Montana [156].
Idaho fescue reproduces from seeds and tillers [261]. Seed production varies: it may produce a fair amount of seed of high viability [282] and it may have poor seed production and weak seedling vigor [119]. Ensign and others [101] observed considerable variation in reproductive success in Idaho fescue among and within ecotypes. Doescher and others [89] found Idaho fescue seeds selected from big sagebrush (Artemisia tridentata) habitat types germinated better and faster over wider temperature and water stress regimes than did seeds gathered from ponderosa pine habitat types. They speculate that this may reflect the variability of the environments in which the plants evolved. Chambers and others [55] note that Idaho fescue establishment from seed in alpine areas is episodic and dependent on proper environmental conditions for both seeds and seedlings in consecutive years.
Seeds are produced in all but the driest years [111], but the percentage of viable seeds varies greatly from year to year [54]. Low seed viability may coincide with low seed fill, which can indicate poor overall development [56]. Although Johnston and others [148] found no relationship between plant basal area and the number of seeds produced in Idaho fescue on Alberta prairie topsoil, they did find that plants not summer-grazed by cattle produced larger seed crops than grazed plants.
Chambers [54] observed a 13, 32, and 53% decrease in seed viability over 1, 2, and 3 years, respectively. Goodwin and others [110] found Idaho fescue seed requires after-ripening. The after-ripening period assures that at least 35% of the seed crop remains dormant for 6 months following dispersal - a strategy that promotes germination after winter precipitation has usually recharged soil moisture. Goodwin and others [111] found percent germination of Idaho fescue seed is related to soil water potential, with fewer seeds germinating at higher water stress levels. Smyth [254] presents evidence of seedbanking in Idaho fescue in British Columbia. Seed dispersal is limited to the immediate vicinity of the plant.
Tillering in Idaho fescue arises from a relatively small budding zone within a compact root crown area [62]. In cases of disturbance in which the root crowns of Idaho fescue survive, tillering may result in a rapid increase in size of Idaho fescue plants in non-competitive environments [145,209].
As a climax species, Idaho fescue is a common component of many "pristine," "undisturbed," or "relict" areas [53,58,106,115,117,121,140,268,272]. It is a major component of late-seral ecosystems, but may also colonize suitable disturbed sites [56]. Idaho fescue communities may rely on periodic disturbance such as soil and slope movement to rejuvenate and maintain vigor of the plant community [144].
In cases where the level of disturbance is such that cover of Idaho fescue decreases (e.g., heavy grazing pressure or severe fire), Idaho fescue succeeds to various native and non-native increaser species. Some examples are bluegrasses (Poa spp.) [171,279,294], sagebrush (Artemisia spp.) [205,310], rubber rabbitbrush (Chrysothamnus nauseosus) and broom snakeweed (Gutierrezia sarothrae) [310], needlegrasses (Achnatherum and Hesperostipa spp.), lupine (Lupinus spp.) [53,146,205], phlox (Phlox spp.)[53,145,205,278], spotted knapweed [205,279,280], yellow starthistle (Centaurea solstitialis) [232], timothy (Phleum pratense) [279], and cheatgrass [171,205,224].
In many areas where Idaho fescue is a late seral community dominant, grasslands are currently occupied by non-native species [33,126,145,155,164] or have species compositions that deviate from historical communities and favor less desirable species [115]. The practice of seeding with native species in restoration efforts has had a "disappointing history," with some non-native species establishing more rapidly and having better longevity than native species (e.g., [152,183]). Johnson and others [145] cite little success with rangeland improvement seedings, because preferred grass species are sought out by grazers immediately after germination. Despite these difficulties, the trend in restoration requires use of native species such as Idaho fescue to satisfy the mandate of ecosystem management [42]. Chambers and others [56] suggest inclusion of late successional species in reseeding programs is important for restoration of ecosystem function.
Idaho fescue is slow to establish [119,286], but once established, has abundant growth of fine leaves that provide effective ground cover, and high yields of tough, fine, fibrous roots that control erosion and improve soil structure [119]. It has poor tolerance to salinity [286], although Ho [134] suggests this may be overcome through inoculation with mycorrhizal fungi. Idaho fescue is suitable for year-round planting (fair in winter) [286], has good stand maintenance [119,286], and retards or prevents the invasion of weeds once firmly established [33,119]. Its close relative, sheep fescue (Festuca ovina), provides excellent ground cover and has a dense root mass that improves soil structure, holds the soil in place, and resists invasion of cheatgrass (Bromus tectorum) and other weeds [168].
The competitive influence of invasive species such as spotted knapweed (Centaurea maculosa) and cheatgrass can interfere with the re-establishment of slower growing, native perennials [169,183]. Borman and others [33,34] found Idaho fescue was 1 of the perennial grasses that, once established, suppressed resident annual plant production. Nasri and Deoescher [209,210] studied the effects of competition by cheatgrass on shoot growth of Idaho fescue and found that increasing cheatgrass cover depleted soil moisture and reduced growth of Idaho fescue; however, Idaho fescue produced greater tiller and leaf numbers than did cheatgrass. Lindquist and others [169] found Idaho fescue had no impact on spotted knapweed growth in greenhouse studies. Furthermore, Marler and others [176] found that vesicular-arbuscular mycorrhizae enhance spotted knapweed's competitive dominance over Idaho fescue.
Site preparation and seeding method are important considerations for rehabilitation of disturbed sites. Everett [103] found that the litter of singleleaf pinyon (Pinus monophylla) appeared to inhibit emergence of Idaho fescue. Vallentine and Stevens [287] suggested using livestock to "graze out" invading cheatgrass as site preparation for reseeding with perennials including Idaho fescue. Seedling emergence is greater when seed is protected with mulch [55,119] or is mixed with an earlier seral, rapid-developing grass [119]. Chambers and others [56] found seeds collected from the Beartooth Plateau in Montana had high viability and high germination under all conditions in the laboratory and suggested that adequate field germination could be obtained by employing a variety of seeding methods such as surface sowing and shallow drilling.
Selection of seed is an important consideration in any revegetation program. Idaho fescue exhibits ecotypic development expressed in differential growth characteristics in seeds collected from different habitat types [89]. Seeds of Idaho fescue collected from a pristine population produced plants with more aboveground biomass than plants collected from degraded sites, and exhibited a different response to competition than those from the degraded site [209]. Plants grown from seed taken from populations that evolved with frequent and intense defoliation tend to have shorter and more prostrate genotypes [209]. Shaw and Cooper [246] claim that Idaho fescue has not been successful in Montana reseeding programs, but used seed collected at low elevations to reseed a site at 9,300 feet (2790 m). Age of seed is also an important consideration when seeding with Idaho fescue [54]. Eddleman [97] found germination was highest with new seed (3 months old) and declined with seed age, although cold temperatures (4 oC) promoted germination for older (15 months) seed. Maguire and others [172] suggest matriconditioning of seed (with Ca2Si) to improve germination rates. Holzworth and Lacey [137] discuss 2 cultivars of Idaho fescue with potential for restoration programs. Information is available regarding the seed collection and production, planting, and monitoring [174].
Majerus [173] lists Idaho fescue among the native plant species found to reestablish naturally on disturbed sites in Yellowstone and Glacier national parks, and cites its use in seed mixtures for restoration of fescue grasslands in those areas. Youtie [315] used seed propagated in the greenhouse to establish Idaho fescue in a small native plant garden on the Columbia River Gorge National Scenic Area, Oregon. A similar small-scale project using propagules of Idaho fescue and 12 other native species was initiated at Jenkin's Creek Park, Washington, in 1989 [8]. Thomas and Gamon [267] had good success establishing Idaho fescue on a restoration project in western Washington (< 10% mortality of planted seedlings). Meier and Weaver [189] provide detailed information on roadside rehabilitation and suggest that Idaho fescue establishes well. Additional guidelines for planting can be found in several publications [246,292,295].
Festuca idahoensis is a species of grass known by the common names Idaho fescue and blue bunchgrass. It is native to western North America, where it is widespread and common. It can be found in many ecosystems, from shady forests to open plains grasslands.
This fescue is a densely clumping long-lived perennial bunch grass with stems from about 30 to 80 centimeters in height.[3] The stiff, short, rolling leaves are mostly located near the base of the tuft. The inflorescence has hairy spikelets which produce large awned fruits. The root system is thick and penetrates deeply into the soil. The roots have symbiotic mycorrhizae. There are no rhizomes; the plant reproduces from seeds and from budding with tillers.
It is similar to, but generally taller and larger than, Poa secunda.[4]
The species can grow in well-soiled areas along with ponderosa pine.[4]
This is a nutritious and preferred forage grass for wild and domestic animals. Typical native grass associates in the far west coastal prairies are Danthonia californica, Deschampsia caespitosa and Nassella pulchra.[5] It is a popular larval host, supporting Lindsey's skipper, sandhill skipper, Sonora skipper, woodland skipper, and western banded skipper caterpillars.[6]
Cultivars, such as "Siskiyou Blue," are produced in the horticulture industry for landscape design and garden use.[7]
Festuca idahoensis is a species of grass known by the common names Idaho fescue and blue bunchgrass. It is native to western North America, where it is widespread and common. It can be found in many ecosystems, from shady forests to open plains grasslands.
