BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Festuca thurberi | Thurber Fescue 



GENERAL BOTANICAL CHARACTERISTICS : 
Thurber fescue is a robust, cool-season, native, perennial bunchgrass.
It is densely tufted and produces thick mats of persistent, dried sheath
and culm bases [5,21,29].  Culms are erect and typically grow from 15.7
to 37.4 inches (40-91 cm) tall [30].  Leaves are scabruous and mostly
basal; heights range from 12 to 18 inches (30-45 cm).  On undisturbed
sites plants can form large diameter bunches.


RAUNKIAER LIFE FORM : 
   Chamaephyte


REGENERATION PROCESSES : 
Sexual:  Thurber fescue regenerates primarily from seed [21,27].  Plants
typically produce abundant seed which germinates readily.  Dramatic
declines in seed production have been documented on mountain grassland
sites in Colorado following a warm, dry growing season [21].  Flowering
is enhanced under cool, moist conditions [21].  Although some autumn
germination occurs, the majority of seeds germinate in the spring soon
after snowmelt, when cool temperatures coincide with high soil moisture
conditions.  Results of laboratory studies indicate optimal germination
occurs at 41 degrees Fahrenheit (5 deg C); at this temperature, 98
percent of seed germinated within 21 days.  Seed storage at 40.1 degrees
Fahrenheit (4.5 deg C) appears to enhance germination somewhat.

Field trials indicate that seeds germinate equally well on both bare
soil and litter.  Seedling establishment is quite high following good
seed years, with increased survival under high moisture conditions.
Apparently Thurber fescue can survive low soil moisture conditions,
which spruce seedling cannot tolerate.  Thurber fescue seedlings are
not, however, as drought tolerant as seedlings of Idaho fescue.

Vegetative:  Vegetative expansion of tufts occurs through tillering.
Thurber fescue is capable of marked tiller production following
herbicide applications; incompletely killed plants were able to recover
pretreatment basal diameters within 4 years [21].  Tiller production
apparently increases under dry conditions.


SITE CHARACTERISTICS : 
Thurber fescue is a mesophytic bunchgrass that is most common in
mountain grassland communities throughout the Colorado Plateau region at
elevations between 8,000 abd 12,000 feet (2,440-3,720 m) [21,26].  At
its lower elevational limits, Thurber fescue occurs with mountain big
sagebrush on drier sites and with mountain silver sagebrush on more
mesic sites at higher elevations.  At its upper elevational limits it is
often contiguous with subalpine herbland communities.  At intermediate
elevations Thurber fescue is a major component of an extensive mosaic of
nonforested communitites interspersed within aspen-spruce-fir forests.
Typical grassland sites include open parks, dry meadows, open slopes,
and broad, rounded ridgetops; open stands of spruce, aspen, and
ponderosa pine comprise the overstory of forested ecotonal sites
adjacent to Thurber fescue grasslands.

Thurber fescue is often locally abundant and sometimes occurs in nearly
pure stands on undisturbed sites.  It typically occupies deep,
well-drained soils on xeric exposures.  Although soil parent materials
are diverse, Thurber fescue appears to grow best on deep shale or
glacial till [15].  Plants usually occupy sandy loam soils but also do
well on heavier clay loams [27].  Site topography ranges from concave to
gently rolling.  Thurber fescue grows well on steep slopes (up to 30
degrees) and stabilizes sites which would otherwise support little
vegetative cover.

Some common grassland associates include Idaho fescue, Letterman
needlegrass (Stipa lettermani), aspen fleabane (Erigeron macranthus),
beauty cinquefoil (Potentilla pulcherrima), Fremont geranium (Geranium
fremonti), and Kentucky bluegrass.

Elevational ranges of Thurber fescue in several western states vary as
follows [7,28]:

        from 6,500 to 12,200 feet (1,982-3,720 m) in Colorado
             10,00 to 11,100 feet (3,048-3,384 m) in New Mexico
             8,000 to 11,000 feet (2,440-3,354 m) in Utah




SUCCESSIONAL STATUS : 
Facultative Seral Species

Self-perpetuating stands of Thurber fescue are characteristic of climax
or late seral mountain grassland communities.  Dense stands apparently
represent an edaphic climax in that soils typify a mature grassland
profile [21].  Thurber fescue is also indicative of climax conditions on
ecotonal shrubland and forested sites adjacent to Thurber fescue
grasslands.  Thurber fescue decreases in response to grazing pressure.
It is apparently a component of early seral situations following fire
due to residual plant survival [12].


SEASONAL DEVELOPMENT : 
Thurber fescue is well adapted to a short and cool growing season.
Plants initiate growth very early in the spring and produce new leaves
while still under snowpack [26], but growth is generally slow until late
June.  The following phenology was reported for mountain grassland sites
in Colorado [21]:

	leaf elongation      early June to mid-July
	flower development   late June to late-July
	seed maturation &    early Auguust to mid-September  
	    dissemination

Related categories for Species: Festuca thurberi | Thurber Fescue