KUCHLER TYPE FIRE ECOLOGY AND MANAGEMENT
KUCHLER TYPE: Northern cordgrass prairie



FUELS, FLAMMABILITY, AND FIRE OCCURRENCE : 
Northern cordgrass prairie is an herbaceous community in which standing
or moving water is present most of the year, and usually at least part
of each day.  The chance of fire in any given year is low due to
moisture conditions [14,26].  However, severe drought causing a drop in
the water table can produce conditions suitable for fire [26].  Marshes
in general have a modal fire-free interval on the order of 30 to 100
years, with a minimum fire-free interval of approximately 5 years.  This
is the approximate amount of time needed for vegetation to achieve high
enough density to carry fire.  In Mississippi, a saltmarsh dominated by
rushes required several-year intervals for sufficient fuel buildup to
support uniform combustion across the marsh [16].  Black rush-dominated
communities are resistant to fire more often than every 3 to 4 years due
to lack of fuels [22].

Some marshes have no history of fire [26].  Naturally caused fires are
generally rare in northern cordgrass prairie [50].  In Florida, salt
marshes (included here are sawgrass marshes, Kuchler type K092) readily
burn.  When adequate fuel protrudes above the water surface and weather
conditions are conducive to fire spread, fires are propagated whether
there is aboveground water or not.  Most Florida saltmarsh fires are
thought to be lightning caused, but some are attributed to humans (arson
or accident) [8].  Cases of spontaneous combustion during severe
droughts [62] and lightning-ignited fires [31] have been reported.


FIRE EFFECTS ON SITE : 
Marsh fires change the physico-chemical properties of soils by oxidizing
the standing vegetative cover, and, depending on soil moisture, by
igniting organic matter on the marsh floor and immediately below the
surface [18].  The removal of shading vegetative cover results in
increased temperatures at the marsh surface [22,23,24].  The effects of
heat on the subsurface are more pronounced during ebb tides,
particularly during tidal regimes that result in only infrequent
flooding (as occurs in winter along the Gulf coast) [24].

Nitrogen, an essential nutrient often limiting to plant growth in marsh
soils, is volatilized by fire [18], but marsh fires also release
nutrients (phosphorus, calcium, magnesium, potassium, and chloride ions)
via ash deposition [24].  Amounts of these nutrients were higher in
shallow soil samples of burned saltmeadow cordgrass communities than
those from unburned communities [14].  The length of time this pulse of
nutrients affects the marsh depends on local hydrology and weather.
There is a gradual decrease in ionic concentrations in Louisiana marsh
soils after fire, attributed to the effects of tidal flushing, rainfall,
and plant uptake of ions [24].  Soil pH increased immediately following
a prescribed fire in a saltmeadow cordgrass-saltgrass community, but in
49 days had declined to a point slightly lower than that prior to the
fire [23].  Hoffpauir [24] reported that soil acidity decreases as a
result of ash deposits; however, Davison and Bratton [14] reported no
difference in soil pH between burned and unburned saltmeadow cordgrass
communities.  When marsh fires consume litter, accretion of sediments
may be slowed.  Severe fire that consumes marsh peats may lead to
reversion of the marsh to more hydric systems [38].

It has been suggested that removing marsh litter by burning may reduce
levels of toxic allelochemicals in marsh soils [55].

Black rush produces large amounts of belowground biomass which serves to
consolidate marsh surfaces.  Replacement of black rush by other species
due to prescribed fires can result in unconsolidated marsh surfaces with
numerous potholes [22].


FIRE EFFECTS ON VEGETATION : 
The effect of fire on marsh vegetation depends on a number of factors
including community composition, season of burning, water level, and
postfire rainfall and hydrology.  Marsh species are killed by hot,
dry-season fires due to destruction of shallow roots.  Less intense
fires remove aboveground material only; many marsh species sprout
vigorously from rhizomes and roots after top-kill [26].  According to
Trabaud [50] most marsh species are, in a sense, preadapted to survive
top-kill by fire; although their ability to reproduce by rhizomes has
not developed in response to fire, when exposed to fire they are readily
able to survive by sprouting [50].

In Georgia, the vegetation of a burned saltmarsh attained 100 percent
cover in the first postfire year [14].  Also in Georgia, smooth
cordgrass marshes prescribed burned in March were characterized by
regrowth consisting of smaller plants with a higher stem density than on
unburned plots [51].  In a Mississippi study to quantify nutrient
mobilization following fire, it was reported that vegetation growth (on
both black rush-dominated plots and big cordgrass-dominated plots) was
stimulated by fire [18].

Cordgrass (Spartina spp.) roots are nearer the surface than those of
bulrushes (Scirpus spp.).  Fires burning in heavy fuels kill more
cordgrass roots than bulrush roots and may result in a reversal of
dominance between saltmeadow cordgrass and Olney threesquare (S.
olneyi) or saltmarsh bulrush (S. robustus).  Typically, bulrushes sprout
after fire within about 1 week; saltmeadow cordgrass may take 2 weeks or
more to sprout.  The dominance reversal is temporary, however.  In 2 or
3 years saltmeadow cordgrass, which has a higher density potential,
regains dominance over bulrushes.  By causing standing water, rainfall
after fire can reduce or eliminate regrowth, and will either encourage
cockspurs (Echinochloa spp.) and spikerushes (Eleocharis spp.), or can
result in a mud flat devoid of vegetation [24].

Winter fires kill the aboveground portions of black rush, the culms of
which retain living tissue over the winter (other grasses are completely
dormant aboveground, and therefore do not lose living tissue during
winter fires).  Other species grow faster than black rush after fire and
may therefore replace it.  In big cordgrass communities, prescribed fire
favors other species at the expense of big cordgrass because of the slow
initial growth rate of big cordgrass after fire and the relatively
greater increases in net primary productivity of other species after
fire (i.e., switchgrass) [22].

Prescribed fire in brackish marshes in Maryland where nutria are present
appeared to retard deterioration of marsh vegetation.  Vegetation
density on control plots decreased between 1974 and 1979; vegetation
density on burned plots decreased also, but at a slower rate.
Vegetation on these plots consisted of Olney threesquare, common reed,
and switchgrass, with some big cordgrass, saltgrass, common spikerush
(Eleocharis palustris), and narrow-leaved cattail [58].

In Mississippi, the elemental composition (nitrogen, phosphorus,
potassium, calcium, and magnesium) of new growth on burned stands of
black rush or smooth cordgrass was generally higher (on a grams/acre
basis) than on unburned stands [18].  Prescribed fire in these stands
resulted in an increase in the net primary productivity of the aerial
portions of the marsh plants [22].

Periodic fire prevents the accumulation of organic matter and impedes
the elevation of the marsh and consequent succession to upland
communities [12].


FIRE EFFECTS ON RESOURCE MANAGEMENT : 
Little is known of the response of wildlife to marsh fires and postfire
succession.  Observations that have been made include:  Marsh wrens
seldom nest in marshes the first postfire year; mud snails are more
prevalent the year following a fire; and mottled ducks (Anas fulvigula)
prefer to nest in rush (Juncus spp.) marshes 3 to 4 years after a fire
[22].

Prescribed fire is a common game management practice in saltmarshes on
the Gulf coast, particularly in Louisiana and Mississippi where large
tracts are often winter burned to maintain productive disclimax genera
such as Scirpus and Eleocharis [18].  Management of some Atlantic coast
saltmarshes for wildlife has also included prescribed fire [34].
Periodic burning of the high marsh areas along the north-central Gulf
coast increases annual primary productivity due to mulch removal and
increased insolation [16].  Vogl [56] stated that marsh fires are useful
in sustaining desirable rhizomatous species such as cattails (Typha
spp.), sedges (Cyperaceae), and rushes by destroying shallow-rooted
competitors (not specified) [56].

Lynch [31] reported that all species of geese seek out and consume new
growth of cordgrasses and saltgrass on burned Louisiana saltmarshes.
Cover burns have been used to attract geese to hunting areas, and to
facitilate hunter access [23,24].

Furbearers (particularly muskrat and nutria) are thought to prefer
certain bulrushes, which increase in abundance following fire [22].

The export of detrital particles into the estuary and near-coastal
marine systems is vital to secondary estuarine productivity.  The impact
of litter removal by periodic burning on nutrient export from tidal
marshes is not well known [18].  Unburned litter may be moved by tides
into high areas or bays after fire [22].


FIRE USE CONSIDERATIONS : 
The typical marsh fire burns at a rate of 3 inches forward per minute
for every 1 mile per hour wind speed.  This would translate, for
example, to about 1 foot per minute with a wind velocity of 4 miles per
hour [24].  Fire intensity and propagation rate are low enough that
furbearing animals and young or wounded waterfowl usually escape marsh
fires without injury or with only minor singeing of the pelage or
feathers [23,24].

If a fire is set in a marsh where the water level is at the soil level
or higher, a vapor zone develops above the wet ground or water level to
a height of about 3 inches.  The vapor or steam appears to protect the
exposed grass stems [24].


FIRE MANAGEMENT CONSIDERATIONS : 
Prescribed fires in Maryland brackish marshes favor Olney threesquare
over saltmeadow cordgrass [58].  The use of prescribed fire on tidal
marshes has been much more prevalent on the Gulf coast than on the
Atlantic coast.  Fires are used to make food available to waterfowl by
burning off "rough" and to encourage the growth of high-grade muskrat
and waterfowl food plants at the expense of less valuable species (black
rush is less desirable, for example).  New postfire growth is more
succulent than unburned vegetation and provides good grazing for geese
in Olney threesquare and cattail meadows.  Fire is also used to thin
dense cover on small marsh islands which harbor predators and to thin
cover to allow hunter access to marshes [46].

There are three types of fire used in salt marsh management:  cover
burns, root burns, and peat fires [31].  Cover burns are usually
conducted in winter (from October 15 to March 1) when the marsh
vegetation is dormant but the marsh surfaces are wet.  Vegetative
material above the surface is consumed by fire, but roots and rhizomes
are undamaged.  Root burns and peat fires are conducted when marsh
surfaces are dry.  Root burns are hot fires which develop in a
relatively dry marsh and alter the composition of the vegetation.  Peat
fires, the most severe of the three, burn holes in the marsh floor thus
creating additional areas of open water [31].  In marshes where nesting
occurs, fire should only be used where cover is too dense for nesting
[46].

Hackney and de la Cruz [22] recommended restraint in the use of fire as
a management tool in saltmarshes.  By this they did not mean that fire
should be excluded; instead, they recommended a plan of prescribed fire
that results in a mosaic of differently aged postfire communities, and
that does not burn an entire marsh in one season [22].


REHABILITATION OF SITES FOLLOWING WILDFIRE : 
NO-ENTRY

Related categories for Kuchler Type: Northern cordgrass prairie