FIRE EFFECTS
SPECIES: Juncus roemerianus | Black Rush 



IMMEDIATE FIRE EFFECT ON PLANT : 
The effects of fire on black rush mortality vary with water depth and
soil moisture.  On flooded sites, and on sites with exposed but
saturated soils, fire may consume aboveground plant portions but leave
underground regenerative structures unharmed.  When a marsh floor is
completely dry, however, fire can burn deep into the soil, consuming the
rhizomes and killing entire stands [24].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
A black-rush-dominated coastal marsh in Mississippi was burned in late
February during low tide when the marsh surface was exposed.  The
immediate effect was the removal of 71 percent of the vegetative cover.
Most culms were only partially burned.  Incomplete combustion of black
rush was apparently due to the formation of a steam layer along the
marsh floor and/or the high moisture content of the culms near the
sediment [9].


PLANT RESPONSE TO FIRE : 
In coastal Mississippi black-rush-dominated marshes, net primary
productivity over a 3-year period was greater on burned than on unburned
marsh.  However, black rush recovered more slowly than did species of
cordgrass.  Three years after burning, total black rush biomass was
lower than before burning [13].

Myers [20] reported that winter burning increased Olney threesquare when
it occurred as a competing subdominant with black rush.  In nearly pure
stands of black rush, however, burning did not change the species
composition of the marsh.


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
Prescribed burning on a 4- to 5-year rotation can be used to maintain
the vigor of black rush marshes.  Burning more frequently would be
difficult because of insufficient fuel.  It takes more than 3 years for
total biomass to reach preburn levels [13].

In southern Florida salt marshes, adequate wind is needed when
conducting a prescribed burn in order to push the fire over open water.
If standing water is not present, soil moisture should exceed 65 percent
on areas underlain by peat, to prevent its ignition.  Saltmarshes
bordered by mangrove (Rizophora mangle, Avicennia germinans) are easy to
burn because the mangrove acts as a fire break.  Where fresh and
saltwater marsh merge, fire can be confined to the salt marsh by
knocking a swath through the fuel at the vegetative boundary and setting
a headfire from that line [27].

Related categories for Species: Juncus roemerianus | Black Rush