FIRE EFFECTS
SPECIES: Poa secunda | Sandberg Bluegrass 



IMMEDIATE FIRE EFFECT ON PLANT : 
Sandberg bluegrass is usually unharmed or only slightly damaged by fire
[51,72].  In a big sagebrush-Thurber needlegrass (Stipa thurberiana)
community near Boise, Idaho, Wright and Klemmedson [71] observed no size
reduction of dormant Sandberg bluegrass 1 to 3 inches (2.5-7.6 cm) in
basal area after either June, July, or August fires (see the Summer
Fire/Combustion Chamber/ID fire case study).  Fire may cause damage if
litter has accumulated at the base of the plant, and/or if plants are
old and pedestaled [72].  Large bunches are more susceptible to damage
than small ones, probably because of greater litter buildup [71] and/or
because the growing points of the elevated plants are no longer
insulated by soil [15,64,72].  Tisdale [62] reported some damage to
pedestaled Sandberg bluegrass in sagebrush with 7 to 14 percent big
sagebrush cover [52].

Seed mortality and postfire seedling emergence:  Fire effects on the
Sandberg bluegrass seedbank are not well documented, but fire may kill
some seed in the upper layer of soil.  In one study, Sandberg bluegrass
seedling emergence was significantly reduced by both "cool" and "hot"
prescribed fires.  In a burning chamber, used onsite in a mountain big
sagebrush community in eastern Oregon, soil surface temperatures reached
a maximum of 219 degrees Fahrenheit (104 deg C) after 30 seconds with
prescribed cool fire and a maximum of 781 degrees Fahrenheit (416 deg C)
after 60 seconds with hot fire.  After the fires, soil samples were
collected from the burn sites from two depths (0-1 cm and 1-2 cm),
samples from the two depths were mixed, and the mixed-depth samples were
used for greenhouse emergence trials.  Number of emerging Sandberg
bluegrass seedlings follows.  Means followed by different letter differ
at the 5 percent significance level; means followed by an asterisk also
differed at the 1 percent significance level [14].

                  Control     Cool Fire     Hot Fire
                  ----------------------------------
                   8.5a*         2.8b        0.3b*


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Sandberg bluegrass generally increases after fire [20,71,72].  Some
variablity in repsonse has been reported, however.  Conditions that may
produce variability such as site differences, prefire plant condition,
and postfire weather are not well documented.

Variability in fire effects is reported for Sandberg bluegrass on big
sagebrush-bunchgrass sites on the Snake River Plain of Idaho.  The sites
were prescription burned in 1936, protected from grazing for 1 year, then
lightly grazed in spring and fall by domestic sheep.  At postfire year
15, Sandberg bluegrass on severely burned plots was producing less than
plants on less severely burned plots.  At a different location in the
same study, there was no difference in Sandberg bluegrass production on
plots of different burn severity after 12 years [10].  After 30 years,
all burned plots were producing more Sandberg bluegrass than unburned
plots, and the differences in Sandberg bluegrass production attributed
to fire severity were negligible.  Annual production of Sandberg
bluegrass (lb/acre, air-dry) on unburned (UB) and burned (B) plots was
as follows [32]:

     ____________________________________________________________
     |     1916        1937        1939       1948       1966   |
     |   ________    ________    _______    _______    _______  |
     |   UB     B    UB     B    UB    B    UB    B    UB    B  |
     |   --------    --------    -------    -------    -------  |
     |    7    10    12    12    33   39    58   88     8   15  |
     |__________________________________________________________|

Increases:  Fire generally favors production of Sandberg bluegrass and
other bluegrasses (Poa spp.) over bluebunch wheatgrass when bluegrasses
and bluebunch wheatgrass occur together.  Bluegrasses may also compete
successfully with cheatgrass as a result of the tillering that occurs
following the reduction of litter and improved insolation caused by fire
[20].  But these postfire gains last only a few years, after which
cheatgrass resumes prefire dominance.

After a mid-July fire in western Montana, an increase in Sandberg
bluegrass cover was noted the first postfire year.  Additionally, the
percentage of Sandberg bluegrass plants bearing flowering stalks was 73
percent on burned plots compared to 44 percent on unburned control
plots [48].

Sandberg bluegrass cover increased significantly (p < 0.05) on burned
plots compared to unburned control plots following September and October
(1978) prescribed burning in Wyoming big sagebrush (Artemisia tridentata
ssp. wyomingensis)-bluebunch wheatgrass near Boise, Idaho.  In postfire
year 1 (1979), precipitation was below normal in spring and near normal
for the rest of the year.  In 1980, precipitation was two times above
normal.  Percent cover of Sandberg bluegrass was [15]:

                    ________________________________
                    |    Control    |    Burned    |
                    |_______________|______________|
                    | 1979     1980 | 1979     1980|
                    |_______________|______________|
                    | 7.03     6.69 | 1.33     2.65|
                    |_______________|______________|

Four years after August wildfire in a big sagebrush-bunchgrass community
in southeastern Oregon, Sandberg bluegrass and other bunchgrasses
dominated burned sites.  Big sagebrush and forbs dominated adjacent
unburned sites [1].

Decline:  Sandberg bluegrass cover was less on burned plots relative to
unburned plots 2 years after spring or fall prescribed burning in Wind
Cave National Park, South Dakota [12].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
NO-ENTRY

Related categories for Species: Poa secunda | Sandberg Bluegrass