FIRE EFFECTS
SPECIES: Bouteloua curtipendula | Sideoats Grama 



IMMEDIATE FIRE EFFECT ON PLANT : 
Fire generally kills the top growth of sideoats grama which is often
burned or charred to within 1/8 to 3/4 inch (3-19 mm) of the root crown.
The rhizomatous variety (or form) of sideoats grama (var. curtipendula)
is generally harmed by fire, particularly in dry years.  In wet years
this form may be relatively unaffected by fire [41].  The bunchgrass
variety (var. caespitosa) reportedly thrives after fire [43].  Specific
comparisons of the effects of fire on these two varieties are, however,
lacking.


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
An Arizona study indicated that lethal temperatures of culm bases of
sensitive perennial grasses such as sideoats grama closely approximated
existing air temperatures at or near ground level during the hot dry
months of summer [19].  During cooler, moister periods the lethal
temperatures of culm bases were much higher [19].  During a 2-year
study, the lethal temperature for sideoats grama ranged from 138 to 164
degrees F (58.8 to 73.8 degrees C) [19].


PLANT RESPONSE TO FIRE : 
The response of sideoats grama to fire varies depending on growth form,
climatic conditions, season of burn, and composition of associated plant
community.  According to Wright and Bailey [43], rhizomatous sideoats
grama is almost always reduced 40 to 50 percent by fire, and at least 2
to 3 years are required for complete recovery [41,43].  The bunchgrass
form is reported to grow vigorously after fire [43].

In general, response is most favorable in wet years and after spring
burns [43,45].  This species is reported to be fairly tolerant of fire
during dormant periods [35].  In short- and mixed-grass prairies,
sideoats grama is generally reduced by fire; in tallgrass prairies it is
often unaffected by fire [43].  In the central and southern Great
Plains, sideoats grama is described as intolerant of fire even in
relatively moist years [42].

The number of inflorescences increased following fire in Kansas but
remained constant after fire in Wisconsin [7].  Plants regenerate
through seed and/or rhizomes.


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
Burning during wet years appears to minimize damage to sideoats grama.
In the southern Great Plains, yields of rhizomatous sideoats grama were
reduced nearly 51 percent in dry years but only 12 percent in wet years
[43].

In some areas the timing of burn can significantly influence the
response of sideoats grama.  Spring burning on northern mixed-prairie
sites is believed to favor warm-season species such as sideoats grama
[46].  Sideoats grama increased following early spring burns in eastern
Kansas [45] and in southern Nebraska [28]:

                         herbage yield (kg/ha)
                Burn                 Mow                  Control
June 1980        152                  82                    49
Sept 1980        155                 244                   160
June 1981        191                 123                    16
Sept 1981        705                  59                   274

Spring burns in eastern Nebraska also favored sideoats grama as compared
with spring or summer mowing [18]:

                         Average % Canopy Cover

                   Spring Burn        Spring Mow        Summer Mow
June Evaluation       trace             trace             trace
August Evaluation       2                 1                 1
 
However, Towne and Owensby [33] found a decrease in sideoats grama after
mid to late spring burns in the Flint Hills of Kansas, and spring
wildfires have reportedly reduced sideoats by as much as 9 to 50 percent
at some locations [41].  Sideoats grama increased regardless of the date
of burning in Wind Cave National Park, South Dakota [40].  Cover of
sideoats grama also increased in response to fire in the Black Hills of
South Dakota as noted below [2]:

                                    % Cover
                        1979       1980       1981
                     (Preburn)
Burn                    1.6         2.0        3.9
Unburned control        1.2         1.8        3.4


                                  % Cover
                       1979            1980            1981
                    (Preburn)
                        1.8             2.3             5.0

Significant increases in sideoats grama have been noted following
drought periods on plots burned in the early to mid spring and winter
[33].

Nutrient levels of sideoats grama are known to fluctuate with fire
history.  A Nebraska study indicated the following nutrient
concentrations [25]:

                   Nutrient Concentrations (% dry weight)
 #Yrs. Burned          0           1           2           3           4  
K (%)               0.58        0.56        0.57        0.58        0.59
Ca (%)              0.36        0.29        0.34        0.30        0.34
Mg (%)              0.13        0.13        0.14        0.14        0.15
P (%)               0.05        0.10        0.10        0.08        0.08 
Total N (%)         0.50        0.54        0.52        0.50        0.55 
Zn (ppm)            17.9        23.0        25.0        26.1        25.0
Cu (ppm)            1.3         1.3         1.2         1.10        1.3
Fe (ppm)           22.9        25.5        29.4        33.7        38.9
Mn (ppm)           18.6        19.2        21.0        19.5        19.2


FIRE MANAGEMENT CONSIDERATIONS : 
NO-ENTRY

Related categories for Species: Bouteloua curtipendula | Sideoats Grama