FIRE EFFECTS
SPECIES: Eragrostis intermedia | Plains Lovegrass 



IMMEDIATE FIRE EFFECT ON PLANT : 
Plains lovegrass culms and leaves are killed by fire.


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 



PLANT RESPONSE TO FIRE : 
Plains lovegrass frequency decreases the first year after fire [28], but
generally increases thereafter [7,9,48].  Seedstalk production sometimes
increases after fire [48].

Plains lovegrass on native grassland in southeastern Arizona was burned
in a July 16 to 17, 1987, wildfire.  When measured in August 1987, it
was reduced to one-third of its prefire cover.  However, by August 1988,
plains lovegrass cover had increased over prefire levels.  By August
1990, it had increased to twice its prefire cover [4,7].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
Plains lovegrass was less on burned than unburned sites during the first
growing season after prescribed fire in Kerr County, Texas.  Live oak
(Quercus fusiformis) and post oak (Q. stellata) savanna containing
plains lovegrass was burned between 12:30 and 1:15 p.m. on February 1,
1982.  Air temperature was 55 degrees Fahrenheit (12.8 deg C), relative
humidity was 42 to 48 percent, and wind speed was 10 to 32 miles per
hour (16-51 km/hr).  Highest recorded fire temperatures were at the
litter surface.  Maximum temperature was 412 degrees Fahrenheit (211 deg
C) at the litter surface in the grasslands surrounding trees.
Temperatures above and below the litter surface were substantially
lower.  In July and early August 1982, samples from quadrats in control
and burned units were collected.  Plains lovegrass biomass was less on
burned than on control sites.  Dominance (lbs/ac), relative dominance
(%), relative frequency, and importance are reported [28]:

                               Relative   Relative
                        Dom      Dom        Freq      Importance 

   Plateau Oak Units
     Control           10.08     6.12       8.09         7.10        
     Burn               3.97     3.37       7.69         5.53
   Post Oak Units                                                       
     Control            5.95     3.33       8.70         6.01        
     Burn               5.43     2.97       6.89         4.92

Plains lovegrass decreased the first growing season following a fire in
south-central Arizona desert grassland, but then increased.  In June
1963 a wildfire burned a 17-square-mile area in Pima County near Sasabe,
Arizona.  After the fire, study sites were located on burned and
unburned slopes at elevations from 4,000 to 4,400 feet (1,219-1,341 m).
Indicators of plains lovegrass basal area (basal area index) before and
for two growing seasons following the fire showed that plains lovegrass
was at first reduced as a result of the fire.  However, by the second
growing season, it equalled or exceeded prefire density [48]:

                           Basal Area Index

          West-facing        North-facing        East-facing
             Sites              Sites               Sites

         Burned  Control    Burned  Control        Burned  

Prefire    0.7     0.7        0.5     0.2            0.8  
1963       0.2     0.4        0.2     0.1            0.3  
1964       1.0     0.5        0.6     0.3            0.8  

The numbers of plains lovegrass plants measured along transects
decreased on burned areas in postfire year 1.  In postfire year 2,
plains lovegrass numbers increased slightly on control sites, but the
increases on burned sites were significantly greater than on control
sites [48]:

          West-facing        North-facing        East-facing
             Sites              Sites               Sites

         Burned  Control    Burned  Control        Burned  

Prefire    19      18         10       8             29    
1963       10      16          9       7             22    
1964       76      30         52      25             71    


Plains lovegrass on the north slope burned area had significantly more
seedstalks and fewer plants without seedstalks during the second growing
season than did the control area.  Plains lovegrass apparently was well
adapted to utilize the above normal winter precipitation of 1963.
Greater seedling survival and larger plants occurred on the north and
west study areas, which received more favorable precipitation, than on
the east study area [48].

Plains lovegrass was more plentiful in recent than old burns in
southwestern Oklahoma prairie and buffalo wallows.  Plains lovegrass was
common on plots close to and in buffalo wallows.  The wallows and
surrounding land were first prescribed burned in early April 1979; some
were burned again in late February 1982.  Sampling occurred between late
June and early July 1982.  At the time of sampling all wallows had 2 to
4 inches (5-10 cm) of standing water.  Exterior quadrats were placed
just adjacent to wallows for comparison of compositional differences
between wallow and other prairie vegetation.  Plains lovegrass was found
only outside the eight buffalo wallows burned in 1972, with average
cover of 43.6 percent.  It occurred throughout the six recently burned
wallows (average cover 18.6% on burned land outside the wallows, 17.3%
at the edge of the burned wallows, and 4.0% in the interior of the
burned wallows) [16].


FIRE MANAGEMENT CONSIDERATIONS : 
In interior chaparral in Arizona, presettlement fire intervals were
usually 50 to 100 years.  Postfire succession is rapid and species
composition is changed little by natural fires [38].

Burning can be used in desert grassland ranges to reduce the number of
shrubs competing with plains lovegrass and other perennial grasses [48].
Grazing should be deferred before burning to insure enough fuel to carry
fire [50,51].
 
Plains lovegrass was subjected to prescribed fire in ungrazed
southeastern Arizona grassland.  The fire had no persistent negative
impact on plains lovegrass density [10].

Related categories for Species: Eragrostis intermedia | Plains Lovegrass