FIRE EFFECTS
SPECIES: Aristida stricta | Pineland Threeawn 



IMMEDIATE FIRE EFFECT ON PLANT : 

The fibrous composition, abundance, and high percentage of dead leaves
make pineland threeawn highly flammable [8].  Burning pineland threeawn
stands at any time of the year tends to remove all aboveground biomass,
leaving only a thin layer of ash on the soil [5,31].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
Clewell [8] speculates that decadent pineland threeawn clumps growing
beneath young hardwood stands may be susceptible to fire.  Under these
circumstances, pineland threeawn may be killed because burning of the
deep accumulations of hardwood leaf litter could raise soil temperatures
around the apical meristems to a lethal level.


PLANT RESPONSE TO FIRE : 
Vegetative growth:  Following fire, pineland threeawn quickly initiates
new top-growth from undamaged underground regenerative structures.  The
leaves grow rapidly, and preburn cover is regained within a few months.
In southern Florida, pineland threeawn grew to a height of 8.6 to 9.4
inches (22-24 cm) 30 days after burning in March and May.  Sixty days
after burning, plant heights were 10 inches (25 cm) on March burns, and
12.6 inches (32 cm) on May burns [40].

Flowering:  Season of burning greatly affects pineland threeawn's
flowering response.  In Florida, it responds vegetatively with little or
no flowering following dormant-season burns, but flowers vigorously
following burning in May, June, or July [1,25].  Platts and others [32]
found that following summer burning, 78.5 percent of pineland threeawn
tillers produced flowering culms, but only 5.9 percent produced
flowering culms following dormant season burns.  Season of burning
appears to be less important in North Carolina.  Prescribed fire in a
longleaf pine savanna in late February resulted in 94 percent of
pineland threeawn plants flowering [5].  Throughout pineland threeawn's
range, fire-stimulated flowering is short lived.  No flowering occurs
during the second fall after fire [31].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
Cattle grazing considerations:  Prescribed fire is used to increase the
nutritional quality of pineland threeeawn.  In general, protein content
and digestibility increase significantly, but return to preburn levels
within 2 or 3 months.  When pineland threeawn was burned in January or
February in Georgia, protein content on March 15 was 10 percent on
burned sites, but only 3 percent on unburned sites.  By June 10, protein
content of burned and unburned plants was similar at 4.2 and 4 percent,
respectively [16].  Without periodic burning pineland threeawn
hearbaceous yeilds decline rapidly.  After 6 to 8 years without fire,
herbaceous yields are reduced by 50 percent [26].  Season of burning
greatly affects short-term yields.  Pineland threeawn produced two and
four times as much herbage 60 days after burning when burned in May or
March, respectively, as compared with burns in October or November [25].
Hughes [40] suggests that grazing should be deferred following burning
until pineland threeawn grows 6 to 8 inches (15-20 cm) tall.

Effects of fire suppression:  Pineland threeawn becomes decadent after
just 8 to 10 years without fire [17].  After 10 to 20 years of fire
exclusion, many clumps become dormant and inconspicuous [8].  On the
Alapaha Experimental Range in Georgia, cover was reduced from 12 to 1
percent after a fire-free interval of 21 years [17].  However, plants
that have survived fire exclusion in a decadent or dormant state for
decades are rejuvenated and grow vigorously after fire [8].

Fuel buildup:  Within 3 or 4 years after fire, a steady state of
aboveground biomass is reached in pineland threeawn stands, which may
equal 5,500 to 7,000 pounds per acre (6,200-7,800 kg/ha).  About 70
percent of this is mulch [31].  Pineland threeawn-dominated stands
produce enough fuel to burn annually [16].  Prescribed fire on a 2-year
rotation is carried out in south Florida flatwoods dominated by pineland
threeawn [12,40].

Related categories for Species: Aristida stricta | Pineland Threeawn