Poa pratensis L.

More info for the terms: codominant, cover, density, fire use, prescribed fire, restoration, woodland

In the Mountain West, Kentucky bluegrass is often more abundant in
recently burned areas than in nearby unburned areas.  Sampling 2- to
36-year-old burns in sagebrush/grassland habitat types in southeastern
Idaho, Humphrey [56] found that Kentucky bluegrass was more abundant in
recent than in old burns.  McKell [76] compared four different-aged
burns in the Gambel oak (Quercus gambelii) zone of north-central Utah.
Kentucky bluegrass cover and density were higher 1 year after a November
fire and 2 years after a January fire, but on 9- and 18-year-old burns
cover and density were the same as on nearby unburned areas.

In the Klamath Mountains of southern Oregon, Kentucky bluegrass was a
codominant grass in open ponderosa pine stands that were burned annually
in the spring for 16 years [123].


The following Research Project Summaries provide information on prescribed

fire use and postfire response of plant community species including

Kentucky bluegrass:

• Response of vegetation to prescribed burning in a Jeffrey pine-California
  
  black oak woodland and a deergrass meadow at Cuyamaca State Park, California


• Effects of fall and spring prescribed burning in
  sagebrush steppe in east-central Oregon


• Vegetation response to restoration treatments in ponderosa pine-Douglas-fir
  forests of western Montana


• Vegetation changes following prescription fires in quaking aspen stands
  of
  Colorado's Front Range


• Seasonal fires in Saskatchewan rough fescue prairie

Kentucky bluegrass

More info for the terms: cover, selection

Kentucky bluegrass provides good cover for small mammals and nongame
birds.  For waterfowl and upland game birds, cover value is fair to
good, depending upon species.

Where abundant, Kentucky bluegrass is preferred nesting cover of
blue-winged teal.  In the Midwest, bluegrass fields are used extensively
for nesting by this duck [8].

Kentucky bluegrass provides poor nesting cover for the ring-necked
pheasant [39].  In south-central South Dakota, Kentucky bluegrass was
important to nesting sharp-tailed grouse, occurring at 84 percent of all
nests [42], however, on the Sheyenne National Grasslands in southeastern
North Dakota, Kentucky bluegrass was seldom used by nesting
sharp-tailed grouse or prairie chickens [70].  Because upland game birds
require dense, residual cover for nesting in the spring, cattle grazing
greatly influences nest site selection [42].

More info for the term: cool-season

Kentucky bluegrass is an introduced, perennial, short to medium-tall,
cool-season, sod-forming grass.  The leaves are primarily basally
attached and are usually 4 to 12 inches (10-30 cm) long [100].  Stems
are numerous in a tuft and grow 12 to 36 inches (30-91 cm) high.  The
inflorescence is an open panicle.  Kentucky bluegrass is shallow rooted
and is intolerant of drought.  Most roots and rhizomes are found within
3 inches (7.5 cm) of the soil surface [40].

Kentucky bluegrass is widely distributed across North America growing in
every state and Canadian province.  It is adapted for growth in cool,
humid climates, and is most prevalent in the northern half of the United
States and the southern half of Canada.  It is not common in the Gulf
States nor in desert regions of the Southwest [125].

More info for the terms: density, fire regime, grassland, prescribed fire, seed

During grassland fires, the fire front passes quickly and temperatures 1
inch (2.5 cm) below the soil surface rise very little [24].  During a
late April prescribed fire in an oak savanna in Minnesota, where
Kentucky bluegrass formed an almost complete sod between bunches of
native tallgrasses, temperatures immediately below the soil surface
rarely exceeded 125 degrees Fahrenheit (51 deg C) [108].  Located a
couple of inches below the soil surface, Kentucky bluegrass rhizomes
survive and initiate new growth after aboveground plant portions are
consumed by fire.  Although the plant survives because of soil-insulated
rhizomes, postfire plant vigor and density are greatly affected by
phenological stage at time of burning (see Fire Effects On Plant).

Seedling establishment is unimportant in immediate postfire recovery.
However, burning may enhance seed germination of Kentucky bluegrass
during the second postfire growing season.  On an Iowa prairie
codominated by big bluestem (Andropogon gerardii var. gerardii),
Indiangrass (Sorghastrum nutans), and Kentucky bluegrass, Kentucky
bluegrass seedlings were more abundant in 1986 on plots burned in May,
June, August, or November of 1985 than on unburned plots [131].

FIRE REGIMES :
Find 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".

More info for the terms: cool-season, cover, frequency, prescribed fire, seed, warm-season

Burning for bluegrass control:  Frequent (annual or biennial) late
spring burning can be used to control Kentucky bluegrass and promote the
growth of warm-season grasses in the Midwest.  The timing of burning is
critical and should take place just prior to the resumption of
warm-season grass growth.  Such burning favors warm-season grasses
because they are dormant at the time of burning.  Conversely,
cool-season species like Kentucky bluegrass are harmed by late spring
fire because they resume growth in the early spring and are thus
actively growing at the time of burning.

In mixed-grass prairie, mid-May has proven to be the most effective time
to burn for Kentucky bluegrass control and has resulted in concomitant
increases in warm-season grasses [31,83].  In native bluestem prairie in
eastern Kansas, Kentucky bluegrass has been nearly eliminated from sites
annually spring burned for decades [112].  In aspen parkland in
northwestern Minnesota, 13 years of annual spring burning in late April,
when bluegrass was 4 to 6 inches high (10-15 cm), reduced Kentucky
bluegrass to about half its original percent composition [107].  After
10 years of biennial spring burning on the Curtis Prairie on the
University of Wisconsin Arboretum, Kentucky bluegrass frequency
decreased from 60 to 13 percent [6].

Burning to promote bluegrass growth:  When using prescribed fire to
promote the growth of cool-season species in the Northern Great Plains,
Kentucky bluegrass will probably respond best to very early spring
(March-April) or late summer (August-September) fires [130].

Disease control:  In Kentucky bluegrass commercial seed fields, burning
after harvest successfully controls several diseases.  It is effective
in controlling ergot (Claviceps purpurea); silver top, caused by the
fungus Fusarium trianctum; and the mite, Siteroptes cerealium.  Burning
also helps control leaf rust (Puccinia poae-nemoralis) and other fungi
harbored in crop residue [48].

Wildlife considerations:  Succulent new grass shoots arising from burned
mountain grasslands are highly palatable to wildlife.  On the Front
Range in Colorado, mule deer and bighorn sheep ate considerably more
Kentucky bluegrass on areas burned in late September than on nearby
unburned areas [102].  Following late October and early November fires
in aspen stands in Colorado, Kentucky bluegrass cover increased and thus
provided more forage to wildlife [99].

Where Kentucky bluegrass is desired for providing ruffed grouse drumming
ground cover, it can be burned when the soil is damp and plants are
dormant [122].

Burning under aspen:  Powell [90] reported that in south-central
Colorado, aspen/Kentucky bluegrass communities have only a moderate
probability of carrying a prescribed fire and only if livestock grazing
is deferred for at least one season.  For fall prescribed burning, the
likelihood of a relatively uniform burning treatment may be increased by
burning after aspen leaf fall [99].

More info on this topic.

More info for the term: geophyte

Geophyte

Kentucky bluegrass is widely distributed across North America, growing
on a wide variety of sites in numerous vegetation types, but grows best
and is most abundant on moist sites where the climate is cool and humid.
In tallgrass prairie it may be abundant on uplands and lowlands because
of abundant annual precipitation, but in mixed-grass prairie it is
abundant only on lowland sites [49,105].  In the West, cool, moist
conditions optimal for growth typically occur on northern exposures, at
moderate to high elevations, and in riparian environments [49].  In the
Southwest and in California Kentucky bluegrass is often confined to cool
mountainous regions [113].  It grows best in full sunlight but will
tolerate light shading if moisture and nutrients are favorable [49,100].
Kentucky bluegrass grows in prairies and fields, mountain grasslands,
mountain brushlands, mountain meadows, riparian woodlands, and open
forests and woods.  It is common along roadsides.

Soils:  Kentucky bluegrass grows on a wide variety of soils, but thrives
on well-drained loams or clay loams rich in humus [113].  It also
thrives on soils derived from limestone [49,100,113].  It is somewhat
exacting in its chemical fertility requirements, needing large amounts of
nitrogen during active growth stages [100].  Optimal soil pH is between
5.8 and 8.2 [100]. 

Elevation:  Elevational ranges for selected western states are as
follows [27,101,124]:

       State                 Elevational Range

        CO              4,000 to 12,000 feet (1,220-3,659 m)
        MT              2,800 to 7,500 feet (854-2,287 m)
        NM              5,576 to 11,480 feet (1,700-3,500 m)
        UT              4,200 to 10,800 feet (1,280-3,290 m)
        WY              4,600 to 9,100 feet (1,400-2,775 m)

Associated species:  Kentucky bluegrass is ubiquitous.  Associated
species in specific habitats are presented below:

Mountain and riparian meadows: redtop (Agrostis alba), smallwing sedge
(Carex microptera), analogue sedge (C. simulata), timothy (Phleum
pratense), Baltic rush (Juncus balticus), meadow barley (Hordeum
brachyantherum), western aster (Aster occidentalis), common yarrow
(Achillea millefolium), strawberry (Frageria virginiana), largeleaf
avens (Geum macrophyllum), wild iris (Iris missouriensis), cinquefoil
(Potentila gracilis), common dandelion (Taraxacum officinale), velvet
lupine (Lupinus leucophyllus), and buttercup (Ranunculus spp.)
[47,61,68,128].

Mountain grasslands: Big sagebrush (Artemisia tridentata), rough fescue
(Festuca scabrella), Idaho fescue (F. idahoensis), cheatgrass (Bromus
tectorum), mountain brome (B. marginatus), common dandelion, snowberry
(Symphoricarpos albus), and rose (Rosa acicularis) [25,89,95]. 

More info on this topic.

This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

More info for the term: cover

   Kentucky bluegrass is found in nearly all SAF cover types

More info on this topic.

This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

More info for the term: shrub

   FRES10  White - red - jack pine
   FRES11  Spruce - fir
   FRES13  Loblolly - shortleaf pine
   FRES14  Oak - pine
   FRES15  Oak - hickory
   FRES17  Elm - ash - cottonwood
   FRES18  Maple - beech - birch
   FRES19  Aspen - birch
   FRES20  Douglas-fir
   FRES21  Ponderosa pine
   FRES22  Western white pine
   FRES23  Fir - spruce
   FRES24  Hemlock - Sitka spruce
   FRES25  Larch
   FRES26  Lodgepole pine
   FRES28  Western hardwoods
   FRES29  Sagebrush
   FRES30  Desert shrub
   FRES34  Chaparral - mountain shrub
   FRES35  Pinyon - juniper
   FRES36  Mountain grasslands
   FRES37  Mountain meadows
   FRES38  Plains grasslands
   FRES39  Prairie
   FRES41  Wet grasslands
   FRES42  Annual grasslands
   FRES44  Alpine

More info on this topic.

This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

   Kentucky bluegrass is widespread and found in nearly all Kuchler Plant Associations.

More info for the terms: cool-season, cover, density, herbaceous, tiller

Plant phenological stage at time of burning greatly influences fire
damage to herbaceous plants.  In general, as new foliage of perennial
grasses reaches full development major food reserves have been depleted,
so that plants are injured most from fires occurring at this time
[24,93].  Because Kentucky bluegrass is a cool-season grass, active in
the spring and fall, it is most susceptible to fire damage at those
times.  Late spring fires, after plants have been growing for about a
month or more, are the most damaging to Kentucky bluegrass.  Sampling at
the end of the first growing season after late spring burning shows that
Kentucky bluegrass basal cover and tiller density are typically much
lower in burned areas than in nearby unburned areas
[11,26,31,43,83,86,87,94,106].

Cool fires conducted when plants are dormant have little effect on
Kentucky bluegrass [62].

Livestock: Kentucky bluegrass is highly palatable in early growth stages
and provides nutritious forage for all classes of livestock.  In the
West, it is often abundant in mountain grasslands, moist and dry
mountain meadows, aspen parkland, and open ponderosa pine forests where
it is eaten extensively by domestic sheep and cattle [15,20,49,60].
Mountain meadows dominated by Kentucky bluegrass may be relatively
limited in extent, but they are highly productive and thus contribute
substantial amounts of summer forage [75].  On mountain rangelands in
northeastern Oregon, Kentucky bluegrass is one of the most important
forage species in cattle and sheep summer diets [55,75].

In eastern North America, Kentucky bluegrass is considered one of the
best pasture grasses [100].  Due to limited precipitation in the West,
however, it provides only fair range forage because biomass production
is relatively low due to summer dormancy [115].  It is seldom seeded on
western ranges but may be used for pasture on moist and cool sites
[100,122].  In irrigated pastures, midsummer production can be
favorable, allowing cattle to gain more weight than if pastured on
orchard grass (Dactylis glomerata) or smooth brome (Bromus inermis)
[100].

Kentucky bluegrass is seldom planted for hay production because yields
are generally low, and plants mature before other hay species are ready
to cut.  It is, however, often found in hay mixtures as an invader
[100].

Wildlife:  Regionally, Kentucky bluegrass can be an important part of
the diets of elk, mule deer, and bighorn sheep [27,49].  On elk winter
range in Rocky Mountain National Park, Colorado, Kentucky bluegrass is
one of the most important grasses eaten by elk [54].  Kentucky bluegrass
is also an important part of fall and winter diets of elk in Wind Cave
National Park, South Dakota [126].  Kentucky bluegrass meadows found
along mountain streams are often preferred foraging areas of wild
ungulates [61].

Bluegrass leaves and seeds are eaten by numerous species of small
mammals and songbirds [72,85].  Bluegrass is often an important food of
the cottontail rabbit and wild turkey [21,39].  Prairie chickens eat
small amounts of seeds [21].  Kentucky-bluegrass-dominated grasslands
provide habitat for numerous species of small mammals [39,78].  In
Kentucky-bluegrass-dominated mountain meadows in Oregon the northern
pocket gopher, Columbian ground squirrel, and mice are a prevalent, and
thus these sites are also important to foraging raptors [62].

Mueggler and Campbell [82] suggest that the aspen/Kentucky bluegrass
community type in Utah is one of the poorest aspen community types for
value as wildlife habitat because of the lack of plant species
diversity.

More info for the terms: forest, herbaceous

Kentucky bluegrass is an introduced plant and is therefore not used in
habitat typing.  It has, however, become naturalized across North
America and often occurs as a herbaceous layer dominant.  In the West,
Kentucky bluegrass frequently occurs as an understory dominant in aspen
(Populus tremuloides), ponderosa pine (Pinus ponderosa), sagebrush
(Artemisia spp.)/bunchgrass (Pseudoroegneria spicata, Festuca altaica,
F. idahoensis), bunchgrass, and riparian habitats.  It is also a common
dominant of midwestern prairies.

Ponderosa pine and bunchgrass habitat types:  Grazing-induced seral
stages in which Kentucky bluegrass is the herbaceous layer dominant are
widespread and common within ponderosa pine/bunchgrass,
sagebrush/bunchgrass, and bunchgrass habitat types [25,57].

Riparian communities:  Kentucky bluegrass is a common understory
dominant of low- to middle-elevation riparian communities throughout the
Mountain West.  These sites are typically gently sloping stream terraces
with a widely spaced overstory of cottonwood (Populus angustifolia, P.
deltoides, P. trichocarpa), water birch (Betula occidentalis), conifers,
or willows (Salix geyeriana, S. lutea, S. exigua) [46,62,88,128].
Kentucky bluegrass also dominates low- and middle-elevation riparian
meadows on broad floodplains and elevated stream terraces [62,88].  In
the Blue Mountains of eastern Oregon and southeastern Washington,
Kentucky bluegrass dominance is an indicator of dry to moist meadow
conditions and soils that are dark brown to black and clayey [45].

Aspen/Kentucky bluegrass communities:  Aspen/Kentucky bluegrass and
aspen/mountain snowberry (Symphoricarpos oreophilus)/Kentucky bluegrass
community types are relatively uncommon but widespread across the
Intermountain Region [80].  In central Colorado, and in the Black Hills
of South Dakota, aspen stands with an understory dominated by Kentucky
bluegrass are fairly common [90,96].  The understory of aspen/Kentucky
bluegrass communities is relatively depauperate [82].

The following publications describe Kentucky-bluegrass-dominated
grasslands, and forests and woodlands where it occurs as a understory
dominant:

Classification and management of riparian and wetland sites in
  northwestern Montana [13].
Classification and management of riparian and wetland sites in central
  and eastern Montana [46]. 
Riparian dominance types of Montana [47].
Riparian zone associations: Deschutes, Ochoco, Fremont, and Winema
  National Forests [58].
Riparian community type classification of Utah and southeastern Idaho
  [88].
Preliminary riparian community type classification for Nevada [68].
Riparian community type classification for eastern Idaho and western
  Wyoming [128].
Ecology and plant communities of the riparian area associated with
  Catherine Creek in northeastern Oregon [61].
A meadow site classification for the Sierra Nevada, California [91]. 
Plant communities of the Blue Mountains of eastern Oregon and
  southeastern Washington [45].
Plant associations of the central Oregon pumice zone [119]. 
Ecology and distribution of riparian vegetation in the Trout Creek
  Mountains of southeastern Oregon [32].
Plant associations of the Wallowa-Snake Province: Wallowa-Whitman
  National Forest [57].
Range plant communities of the Central Grasslands Research Station in
  south-central North Dakota [66].
Classification of native vegetation at the Woodworth Station, North
  Dakota [79].
Aspen community types of the Intermountain Region [80].
Aspen community types of Utah [82].
Aspen community types on the Caribou and Targhee National Forests in
  southeastern Idaho [81].
Aspen community types of the Pike and San Isabel National Forests in
  south-central Colorado [90].
Classification of quaking aspen stands in the Black Hills and Bear Lodge
  Mountains [96].
Classification of deer habitat in the ponderosa pine forests of the
  Black Hills, South Dakota [109].

More info for the term: graminoid

Graminoid

More info for the terms: cool-season, density, forbs, presence, restoration, warm-season

Grazing:  The desirability of Kentucky bluegrass on rangeland is limited
because of low production, summer dormancy, and propensity to invade
native grasslands.  This grass is highly resistant to grazing because
growing points remain belowground throughout the growing season, and it
has a low ratio of reproductive to vegetative stems [30].  Few grasses
are able to withstand heavy grazing as well as Kentucky bluegrass.  It
increases rapidly on overgrazed pastures and ranges, and its presence is
usually an indication of poor grazing management in the past.

On tallgrass prairie rangeland, Kentucky bluegrass density is best kept
in check by a combination of grazing management and prescribed burning.
It was effectively controlled in eastern Kansas with either season-long
or intensive early season grazing combined with late spring prescribed
burning [65].  Kentucky bluegrass also decreases with a combination of
late spring mowing and raking, which simulates burning [86].

In the Mountain West, Kentucky bluegrass is well adapted to meadows
which have seasonally high water tables and midsummer drought [120].  It
has become naturalized and dominates many meadows once dominated by
tufted hairgrass (Deschampsia cespitosa) and sedges.  Replacement of
Kentucky bluegrass with the original natives is impractical because of
its competitive ability.  Even after 11 years of rest from livestock
grazing, a Kentucky bluegrass meadow in central Oregon did not advance
toward dominance by tufted hairgrass [118].  For livestock use, these
sites are best managed under a grazing system other than season long
use.

Bluegrass control with herbicides:  Herbicides are used for cool-season
grass control prior to planting warm-season grass species for prairie
restoration, and for cool-season grass suppression in overgrazed
pastures.  Atrazine and glyphosate effectively control Kentucky
bluegrass.  On rangeland in eastern Nebraska, April application of
atrazine or glyphosate reduced Kentucky bluegrass relative composition
by 98 and 96 percent, respectively, after one growing season [121].
After two growing seasons, bluegrass recovery was negligible.  This
allowed yields of native warm-season grasses to increase dramatically.

Soil stability:  Because of its shallow root system, Kentucky bluegrass
is generally not as good a soil stabilizer as the native grasses and
forbs it replaces.  In riparian settings, it is ineffective in
stabilizing streambanks.  Erosion and channel downcutting may occur,
especially where excessively grazed [47,62].

Flood resistance:  Kentucky bluegrass is intolerant of prolonged
flooding, high water tables, or poor drainage [122].

More info for the term: fresh

Early growth stages of Kentucky bluegrass are nutritious.  After
flowering, nutritive value declines, and the plant may only provide for
the minimum maintenance energy needs of ruminants.  Crude protein
content of leaves, for example, is often greater than 20 percent in
early spring before elongation of flowering culms.  After flowering,
protein content of leaves drops to less than 5 percent [74].  Similarly,
fiber content increases as plants mature.

The National Academy of Sciences [84] reported the following nutritional
information for fresh, aerial parts of Kentucky bluegrass during various
growth stages:

                   % Protein    % Ash   % Crude Fiber   % N-free Extract
growth stage      (N x 6.25)       

immature             17.5        9.4        25.4             44.2
early bloom          16.6        7.1        27.4             44.9
mid-bloom             13.2        7.6        29.2             46.1
milk stage           11.6        7.3        30.3             47.2
dough stage           9.5        6.6        34.8             46.0
mature                9.5        6.2        32.2             49.0
over ripe             3.3        6.3        42.1             47.0

In the Black Hills of South Dakota, Kentucky bluegrass plants growing in
shaded locations had more crude fiber and less nitrogen-free extract
than plants growing in full sunlight.  Although plants from shaded
locations were still nutritious for cattle, they were less palatable
[74].

     AL  AK  AZ  AR  CA  CO  CT  DE  FL  GA
     HI  ID  IL  IN  IA  KS  KY  LA  ME  MD
     MA  MI  MN  MS  MO  MT  NE  NV  NH  NJ
     NM  NY  NC  ND  OH  OK  OR  PA  RI  SC
     SD  TN  TX  UT  VT  VA  WA  WV  WI  WY
     AB  BC  MB  NB  NF  NT  NS  ON  PE  PQ
     SK  YT  MEXICO

Kentucky bluegrass is one of America's most popular lawn grasses.  It
withstands considerable abuse, and it is often used as a sod-grass at
campgrounds, golf courses, and ski slopes [97].

More info for the term: warm-season

Kentucky bluegrass is highly palatable to most large grazers during the
spring when it is green and succulent.  When semidormant in the summer,
palatability is much reduced.  In moist mountain meadows, palatability
remains somewhat high during the summer.

In aspen parkland and mountain grasslands, Kentucky bluegrass is often
one of the most preferred grasses of cattle and sheep [15,75].  In some
Kentucky bluegrass-dominated meadows cattle grazing pressure can be
severe.  For example, along Catherine Creek in northeastern Oregon,
cattle preferred feeding in both dry and moist Kentucky bluegrass
meadows over other riparian vegetation types.  Kentucky bluegrass was
utilized from 55 to 79 percent in dry meadows and from 67 to 80 percent
in moist meadows [60].  In central Oregon, Kentucky-bluegrass-dominated
meadows are more palatable into midsummer than drier meadows dominated
by Cusick's bluegrass (Poa cusickii) [120].

In the Black Hills of South Dakota, sedges (Carex spp.), wheatgrasses
(Agropyron spp.), and timber oatgrass (Danthonia intermedia) were
preferred by cattle over Kentucky bluegrass [114].

Kentucky bluegrass was one of the most preferred grasses of cattle under
season-long grazing in the ponderosa pine type of northern Arizona [20].

In the prairie states, Kentucky bluegrass is most palatable to livestock
in the spring before warm-season grasses have resumed growth [21].

Palatability to wildlife in western states is rated as follows
[27,62,97]:

                         CO      MT      ND      OR      UT      WY
Pronghorn               ----    ----    poor     ----   good    good
Elk                     good    good    ----     good   good    good
Mule deer               ----    fair    poor     good   good    good
White-tailed deer       ----    good    poor     good   ----    good
Small mammals           good    fair    fair     ----   good    good
Small nongame birds     ----    fair    fair     ----   fair    good
Upland game birds       ----    fair    poor     ----   fair    good
Waterfowl               ----    good    good     ----   fair    good

More info on this topic.

More info for the terms: phenology, seed

Kentucky bluegrass is one of the first grasses to resume growth in late
winter or early spring.  It grows rapidly, and in many states it flowers
in May [19,27].  In Kentucky and Missouri, seeds are mature by mid-June
[125].  By midsummer plants become nearly dormant.  With cool
temperatures and precipitation, growth resumes in the fall and continues
until daytime temperatures approach freezing [97,105].

Flowering time for several states is as follows:

Montana - late May and early June [97]
North Dakota - late May and early June [69]
Nebraska - May [105]

Kentucky bluegrass phenology was studied over a 3-year period on the
Sheyenne National Grasslands in southeastern North Dakota.  Timing of
phenological events was as follows (average dates for the 3 years
studied) [69]:

Resumption of spring growth - green leaves observed during snowmelt in
mid-March, but rapid growth began in early April.

Flowering - flower stalks appeared in mid-May.  Most flowering occurred
in late May and early June.  Nearly all plants completed anthesis within
one week.

Seed maturation - mature seeds were observed in mid- to late June.  Seed
stalks became dried after anthesis and were easily removed by wind.
Most stalks were removed by midsummer. 

Senescence and regrowth - maximum leaf height occurred in mid-June and
leaf senescence occurred shortly thereafter.  Plants were semidormant
during midsummer.  Large amounts of vegetative regrowth began in late
July and early August.  Forty percent of leaves present at the end of
August were new growth, which continued for a short time after the first
hard frost.

More info for the terms: cool-season, cover, density, fire frequency, frequency, habitat type, prescribed fire

Kentucky bluegrass's fire response varies greatly depending on season of
burning, fire frequency, and postfire precipitation and soil moisture.

Season of burning:  Kentucky bluegrass postfire cover, biomass, and
flower stalk density are often greatly reduced during the first postfire
growing season by a single late spring fire.  Three examples are
presented to demonstrate rather typical first-year responses to late
spring burning: (1) in mixed-grass prairie unburned for several years in
north-central Nebraska, a single prescribed fire in mid-April or mid-May
greatly reduced Kentucky bluegrass basal cover in October, with cover on
burned plots only half that found on unburned plots [83], (2) after a
single mid-April fire on a tallgrass prairie site unburned for several
years in Iowa, Kentucky bluegrass relative biomass decreased from 80
percent to 25 percent during the first postfire growing season [53], and
(3) in the mountains of western Montana, Kentucky bluegrass frequency
was reduced 27.5 percent by a single late May fire in a
sagebrush/bunchgrass habitat type [18].

Kentucky bluegrass biomass production and density may be unaffected or
increase after burning at other times of the year, such as early spring,
summer, or fall.  It consistently recovers more quickly from burning at
these times of year than from burning in late spring.

In fields dominated by cool-season grasses in Wisconsin, Kentucky
bluegrass was reduced to one-fifth of its original density after 6 years
of annual burning in May; annual burning in March or October did not
affect Kentucky bluegrass density [23].  A different study in Wisconsin
showed that flower stalk density was reduced 70 percent by three annual
mid-May prescribed fires but was slightly increased by annual burning in
late March or early April [51].  Although summer grass fires can be
relatively intense, Kentucky bluegrass is dormant at this time.  It may
not be harmed by summer burning, and if precipitation is favorable, it
may even increase.  In mixed-grass prairie in north-central South
Dakota, Kentucky bluegrass frequency increased or remained unchanged on
uplands burned in early August followed by a wet spring, but decreased
on uplands burned in summer following a dry spring [103,104].  Kentucky
bluegrass's density tripled 1 year after late October and early November
low-intensity prescribed fires in aspen stands in Colorado [99].  In
ponderosa pine habitat types in British Columbia, Kentucky bluegrass
biomass was unchanged by an October prescribed fire [110].

Fire frequency:  Even after late spring burning, unless burned a second
time, Kentucky bluegrass density and cover often return to prefire
levels within 1 to 3 years.  For example, burning in May or June in Wind
Cave National Park, South Dakota, consistently reduced Kentucky
bluegrass canopy coverage, height, shoot density, flower stalk density,
and biomass during the first postfire growing season but not during
postfire years 2 and 3 [87].  In fact, biomass and density were often
greater on burned plots than on control plots during postfire year 2.
Other studies in mixed-grass prairie have shown Kentucky bluegrass cover
can be reduced for 2 or 3 years by a single late spring fire [34,83,94].

Kentucky bluegrass cannot withstand frequent spring burning.  In the
tallgrass prairie, its density decreases with increased fire frequency,
and it may be eliminated from sites that are burned annually for several
years [1,5,28,44,65,77].  In the Flint Hills of northeastern Kansas,
Kentucky bluegrass canopy coverage under different burning regimes was
30.3 percent on an area unburned for 11 years, 7.0 percent on an area
burned 1 and 5 years before sampling, and 0 percent on an area burned
annually for 5 years [1].  A similar response was observed on a
reconstructed tallgrass prairie in Illinois subjected to the following
burning treatments [44]:

not burned = unburned for 19 years
burned twice = burned Feb. 28, 1952 and April 16, 1959
burned three times = burned Feb. 28, 1952; April 16, 1959; and May 2, 1961
burned four times = burned Feb. 28, 1952; April 16, 1959; May 2, 1961; and
                    May 10, 1962

Sampling at the end of the 1962 growing season showed the relative
percentage of bluegrass (P. compressa and P. pratensis) shoot biomass
decreased with increased burning frequency in two community types as
follows:

                               Burning Treatment 
                 not burned     burned twice    burned      burned
                                               3 times     4 times
Community type
big bluestem        23.4             18.3         4.6          0
indiangrass         18.6             15.9         3.3          0

Vogl [117] sampled several pine barrens in northern Wisconsin and
reported that Kentucky bluegrass frequency either increased or decreased
within 1 year of a single spring fire but that Kentucky bluegrass was
eliminated on sites spring burned more than once every few years.

Influence of postfire moisture:  Kentucky bluegrass is more susceptible
to fire damage on ridge sites than in depressions, especially in dry
years [52].  In fact, in swales and low prairie sites that receive
upslope moisture, Kentucky bluegrass often increases after spring
burning.  In bluegrass fields in Wisconsin, Kentucky bluegrass density
and biomass increased in depressions but decreased or remained unchanged
on ridgetops after two successive mid-April fires [129].  In eastern
South Dakota, Kentucky bluegrass recovered well from early May burning
if irrigated.  On burned but unirrigated plots, however, biomass
decreased sharply [12].  In eastern North Dakota, lowland and upland
prairies were burned on May 8, 1966.  Postfire data on August 4, 1966
showed that Kentucky bluegrass frequency increased on lowlands but
remained unchanged on uplands.  Biomass on both uplands and lowlands
decreased, but the decrease was much greater on uplands [43].  When
postfire growing season precipitation was "considerably below normal" in
Wind Cave National Park, South Dakota, Kentucky bluegrass biomass on
burned areas was less than half that found on unburned areas whether
burned on September 18, February 13, or April 10 [37].

In a sagebrush/rough fescue habitat type in Montana, Kentucky bluegrass
biomass increased the first summer after a mid-May prescribed fire [95].
This increase was unexpected because bluegrass should be susceptible to
burning at this time.  This increase may be due to the high moisture
availability in surface soils at this site due to concave slope shape.
In contrast, another study in western Montana found Kentucky bluegrass
decreased after a prescribed fire on May 24 in a sagebrush/fescue
habitat type [18].

More info for the terms: herb, rhizome

   Rhizomatous herb, rhizome in soil

More info for the terms: cover, fresh, herbaceous, rhizome, seed

Kentucky bluegrass is a vigorous herbaceous competitor.  Not only does
it spread by rhizome expansion, it also produces abundant seed which
accounts for good seedling recruitment and establishment on disturbed
sites.

There are 2.1 to 2.2 million seeds per pound (4.6-4.8 million/kg).
Germinative capacity varies from 75 to 94 percent.  Seeds require light
for germination [35].

In eastern Washington, fresh seed sown in July began germinating on
November 18; seedling emergence continued into December beneath an
occasional snow cover.  Autumn seed germination was regulated more by
temperature and moisture than by the amount or quality of light [14].

More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

    1  Northern Pacific Border
    2  Cascade Mountains
    3  Southern Pacific Border
    4  Sierra Mountains
    5  Columbia Plateau
    6  Upper Basin and Range
    7  Lower Basin and Range
    8  Northern Rocky Mountains
    9  Middle Rocky Mountains
   10  Wyoming Basin
   11  Southern Rocky Mountains
   12  Colorado Plateau
   13  Rocky Mountain Piedmont
   14  Great Plains
   15  Black Hills Uplift
   16  Upper Missouri Basin and Broken Lands

More info on this topic.

More info for the terms: climax, herbaceous

Kentucky bluegrass is extremely competitive.  Due to past grazing and
lowering of water tables in western riparian habitats, Kentucky
bluegrass now dominates many sites once occupied by tufted hairgrass,
woolly sedge (Carex lanuginosa), widefruit sedge (C. eurycarpa), aquatic
sedge (C. aquatilis), bluejoint reedgrass (Calamagrostis canadensis),
Cusick bluegrass, and willows [47,62,88].  Once it has gained dominance,
it is persistent and remains a relatively stable community component.

In the Intermountain West, aspen/Kentucky bluegrass communities are
grazing-induced seral stages which have replaced the following climax or
near climax communities [80,82]:  aspen/mountain snowberry/Fendler
meadowrue (Thalictrum fendleri), aspen/mountain snowberry/pinegrass
(Calamagrostis rubescens), aspen/Fendler meadowrue, aspen/pinegrass,
aspen/mountain snowberry/elk sedge (Carex geyeri), and aspen/elk sedge.

In ponderosa pine and bunchgrass habitat types, Kentucky bluegrass is
often the herbaceous layer dominant on sites with a history of past
grazing abuse.  Daubenmire [25] called such sites a "zootic climax"
because even after the grazing disturbance has been stopped for many
years, there is no indication that Kentucky bluegrass will give way to
the native climax species. 

The currently accepted scientific name of Kentucky bluegrass is Poa
pratensis L. [124].

Kartesz and Kartesz [59] recognized the following subspecies:

Poa pratensis subsp. agassizensis (Boivin & D. Love) Taylor & McBryde
Poa pratensis subsp. alpigena (Fries) Hiitonen
Poa pratensis subsp. angustifolia (L.) Gaudin
Poa pratensis subsp. pratensis

Kentucky bluegrass is generally considered to be nonnative to North
America. Some botanists argue, however, that populations in remote
mountain meadows of the West may be native (see discussion by Cronquist
and others) [22].

Poa pratensis naturally hybridizes with several other species within
the genus, including P. secunda, P. arctica, P. alpina, P. nervosa, P.
reflexa, and P. palustris [124].

More info for the terms: cover, reclamation, seed

Kentucky bluegrass's value in rehabilitation work is limited because it
is slow to establish cover, is not drought tolerant, and has high soil
fertility requirements [116].  When planted in seed mixtures, it often
takes 2 or 3 years to become established.  Once established, however, it
is persistent and forms a dense sod which promotes soil stability [49].
It is used in Alaska, Colorado, and Wisconsin for soil stabilization
along highway roadbanks [49].  In the West, it is probably best suited
for establishing cover in disturbed subalpine habitats [9]; however,
Hassel and others [50] recommend Canada bluegrass (Poa compressa) over
Kentucky bluegrass for revegetation projects on mountain sites in the
Intermountain West.

A summary of Kentucky bluegrass's performance at numerous reclamation
sites has been published [49].