FIRE EFFECTS
SPECIES: Scirpus americanus | Olney Threesquare 



IMMEDIATE FIRE EFFECT ON PLANT : 
Only aboveground (or abovewater) plant parts of Olney threesquare are
removed by fire when water levels are aboveground or only slightly below
the soil surface.  Thus the plant survives most fires because
perrenating underground organs are not harmed.  However, under severe
drought conditions, fire can burn deep into peat layers and kill Olney
threesquare by charring or consuming the rhizomes .


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
In comparison with marshhay cordgrass, Olney threesquare's rhizomes are
more deeply buried in the soil.  If burned when marsh soils are dry,
Olney threesquare typically suffers much lower rates of mortality where
these plants grow in mixed stands [12].


PLANT RESPONSE TO FIRE : 
Olney threesquare often sprouts within a week of burning [11,12].  In
Louisiana, Olney threesquare culm density reached or exceeded preburn
density within 4 weeks of burning whether burned in October, December,
or February [5].  Another study in Louisiana similarly found that
burning during different seasons had no effect on Olney threesquare culm
density [11].  In this study, plants quickly sprouted whether burned in
fall, winter, or spring as long as water levels were even with or
slightly above the soil surface at the time of burning.  However,
maximum leaf growth occurred in March and April when soil temperatures
rose above 60 degrees Fahrenheit (16 C), no matter what time of year
plants were burned.


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
Marshhay cordgrass outcompetes and replaces Olney threesquare in Gulf
Coast brackish marshes that remain unburned for a few to several years.
In a Louisiana brackish marsh, Olney threesquare was "weeded out" by
marshhay cordgrass after just 3 years of fire protection [28].
Prescribed burning every 2 or 3 years, however, maintains subclimax
stands of Olney threesquare [12].  For Louisiana coastal marshes, O'Neil
[18] recommended burning Olney threesquare stands anytime from October
10 to January 1 when water levels are between 0 and 2 inches (0-5 cm)
above the soil surface.

Related categories for Species: Scirpus americanus | Olney Threesquare