FIRE EFFECTS
SPECIES: Cladium jamaicense | Sawgrass 



IMMEDIATE FIRE EFFECT ON PLANT : 
In general, fires carry well in both drained and flooded sawgrass
stands, consuming most of the aboveground or abovewater biomass.  On
flooded sites, plants are burned down to a uniform height, usually
several inches above the water surface [8,27].

The effects of fire on sawgrass mortality vary with water depth and soil
moisture.  On flooded sites, and on sites with exposed but saturated
soils, no underground regenerative structures are harmed.  As soils
begin to dry, however, some meristems are killed by the heat of fire.
When soils become dry because of drought or marshland drainage by man,
fires can burn deep into peat layers, consuming all of the rhizomes and
roots, thus killing entire stands [8,27].

Sawgrass typically sprouts and grows rapidly after fire, but is killed
if water levels rise rapidly, keeping the new growth completely
submerged [14].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
In the Everglades, peat-destroying fires have been recorded in the
1920's, 1937, 1945, 1946, 1947, 1951, 1952, 1962, and 1965 [12].  In
some areas, the peat burned to bedrock or marl soil [5].  These fires
destroyed "tremendous expanses" of sawgrass communities, which were
replaced by maidencane or shallow-water aquatic communities.  The
increased frequency of these severe fires, which would normally only
occur under extended drought conditions, is a result of man's
alterations of the Everglade's hydrology (lowering of the water table).


PLANT RESPONSE TO FIRE : 
Leaf growth:  If rhizomes and meristems are undamaged, regrowth is rapid
following fires occurring at any time of the year.  Plants may sprout
the day after burning, and within 2 weeks, leaves are commonly 8 to 16
inches (20-40 cm) tall [8].  Within 6 months plants have typically grown
3 to 6 feet (1-2 m) tall, and within 1 to 2 years approach preburn
heights [8,12,23,25,28].

Cover and weight:  Most of the cover in unburned sawgrass stands is from
accumulated litter [8].  Thus, even 1 year after burning, cover remains
low because the cover is entirely from live leaves.  In the Everglades,
sawgrass regained about 50 percent of its preburn cover and 70 percent
of its standing crop (aboveground dry weight) within 1 year of burning
[8].  If fire damages the meristems, regrowth is much slower.  A
wildfire burned sawgrass stands in the Everglades in May 1971, an
extreme drought year.  Eighteen months after burning, the standing crop
of burned stands was only 38 percent of that of unburned stands [24].

Density:  In the Everglades, sawgrass density was neither increased
nor decreased following burning when standing water was present [8].  

Flowering:  Fire does not seem to stimulate flowering in sawgrass.
Flower stalks are usually produced the second year following burning
[5], but have been observed in April following January and February
prescribed burns [12].  


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
Growth rates following burning vary with soil moisture and season of
burning.  The most rapid growth occurs following winter or spring
burning on sites that are flooded or have saturated soils.  Tilmant [25]
observed sawgrass growing up to 2.5 feet (0.75 m) 2 weeks after an early
March burn that took place when water was at the ground surface level.

In the Everglades, plants regained 73 to 98 percent of their preburn
height within 7 to 12 months after burning [8] :

                                       date burned
                      --------------------------------------------------
                       Oct. 31, 1971   Dec. 9, 1971  March 8 or 16, 1972

avg. preburn height       107 inches    133 inches       93 inches 

avg. postburn height       90 inches     97 inches       92 inches
in Oct. 1972

preburn height
regained by Oct. 1972        85%           73%             98%

The sites burned in March, 1972, had burned 1 year earlier, and thus
preburn leaf height was lower than normal.  Nevertheless, the rate of
growth following this spring burn was greater than the fall burn growth
rates.  


FIRE MANAGEMENT CONSIDERATIONS : 
Sawgrass leaves have a high surface area-to-volume ratio, and, after a
few years without burning, stands accumulate much of this dead fuel
which promotes fire spread.  In general, dense stands are easy to ignite
and burn hot.  They will burn within hours after a rain and when water
levels are a foot (0.28 m) or more deep [27].  The highest temperatures
during sawgrass fires occur at about 1.6 feet (0.5 m) above the water
surface where most litter accumulates.  During sawgrass fires in the
Everglades, maximum temperatures at this height ranged from 576 to 750
degrees Fahrenheit (302-399 C) [8].

Fires will generally not carry in sparse sawgrass stands when water is
present or soils are saturated.  In dense sawgrass stands in the
Everglades, when water was present, fire spread in a fingering or mosaic
pattern and stopped when it reached sparse sawgrass, open glade, or
dense hardwood stands [8].  Containment is not a problem when burning
sawgrass because most prescribed burning takes place when water is
present, and thus fire usually stops when it reaches an area of sparse
fuel more than a few feet (1 m) wide [27].

In sawgrass stands burns are prescribed mainly to reduce wildfire
hazard.  To accomplish this, burning has to remove much of the
accumulated litter.  Prescribed burning can be done safely anytime the
soil is wet, but is usually done when several inches of water is present
to allow the use of airboats [27].  Burning when water is present also
ensures sawgrass survival because the water layer protects the rhizomes.
Conversely, prescribed burns can be used to kill sawgrass if burning
takes place when the marsh floor is completely dry.  Whenever possible,
headfires or spot fires should be used when burning sawgrass [27].
Pushed by the wind, these fires will cross areas of sparse fuels
backfires are unable to.  Also, because headfires are fast-moving, they
are less likely to dry-out and ignite any elevated areas of organic
soil.

Related categories for Species: Cladium jamaicense | Sawgrass