FIRE EFFECTS
SPECIES: Phragmites australis | Common Reed 



IMMEDIATE FIRE EFFECT ON PLANT : 
Flammability:  Common reed stands are typically dense and contain much
dead material.  Standing dead canes and litter often constitute twice as
much biomass as living shoots [39].  This abundant dead fuel carries
fire well, allowing stands to burn during midsummer when the current
year's shoots are green.  At the Delta Marsh in Manitoba, spring, summer
or fall burning removed more than 90 percent of living and dead plant
material [43].  In a Nebraska common reed stand, a late February
prescribed burn when the marsh was frozen removed all aboveground
vegetation except for a 2- to 6-inch-tall (5-15 cm) stubble layer which
apparently resulted from a vapor zone from accompanying steam [37].

Rhizome damage:  Most fires cause little damage to common reed because
the rhizomes are sufficiently protected by soil.  Rhizomes can be
damaged, however, by deep-burning fires which can occur when the soil is
dry and the humidity of the litter and stembase is low.  The effects of
severe burning depend on the degree of damage inflicted upon the
rhizomes.  Following some severe fires, shoot emergence the following
spring can be delayed for 1 to 2 months.  The most damaging fires occur
during drought years when entire peat layers can be consumed.  This
destroys the rhizomes and eliminates common reed from the area [21].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Most fires favor common reed.  Fire removes the standing dead canes and
accumulated litter, allowing the soil to warm up rapidly in the spring,
which results in earlier shoot emergence [43].  Stands burned during the
spring (before shoot emergence or during early growth stages), late
summer or fall (plants green or dormant), or winter recover quickly;
preburn stem density and biomass are attained within one growing season
[44].  Although plants burned during the summer usually initiate new
top-growth within a few days, stem density is greatly reduced, and stems
regrow to only about half of normal height before killing frosts occur.
Furthermore, early to midsummer burning during the peak of plant growth
(when carbohydrate reserves are lowest) reduces stem density and
aboveground biomass for two to four growing seasons [5,44,49].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
At the Delta Marsh in Manitoba, common reed plots were burned on August
1, October 7, and May 11.  The following spring, shoot emergence
occurred on May 1 on fall- and summer-burned plots, on May 19 on
spring-burned plots, and on May 26 on controls.  At the end of the first
full growing season following burning, total aboveground biomass
increased on the spring-burned plots and remained unchanged on
fall-burned plots.  Biomass declined on the summer burn, but the
decrease was short-lived.  By the end of postfire year 2, aboveground
biomass returned to preburn levels.  In the stands burned on August 1,
plants grew to 23 inches (58 cm) in height before they were killed by
frost in late October [43,44].

Another study at the Delta Marsh used summer burning in conjunction with
marsh drainage in an attempt to thin dense common reed stands [49].
Following a fire on July 21, stems grew to 4 inches (10 cm) in height
within 10 days after burning, and reached 23 inches (60 cm) in height
before being killed by frost.  During the second growing season plants
grew to 50 inches (126 cm) in height, but stem density was 80 percent
below normal.  Stem density remained lowered even after three growing
seasons.

When measured in June, stem density increased or remained stable in
common reed stands burned the previous June 15, August 6, or August 24
in a Utah marsh.  However, stem density was 25 to 50 percent less than
unburned controls on sites burned June 29, July 13, or July 27.  


FIRE MANAGEMENT CONSIDERATIONS : 
The best way to reduce common reed with prescribed burning is to burn
during the summer when carbohydrate reserves in the plant are low and
when the soil is dry [21].  From a wildlife standpoint, this opens up
the stands, making them more attractive to waterfowl [49].

Using summer burning to completely eliminate common reed is difficult.
"Root burns", in which prescribed fires burn deeply into organic soils
and consume the rhizomes, will probably only work on marshes where the
water can be completely drained or on marshes experiencing severe
drought [26].

In Utah, dalapon applied as an aerial spray 48 days after midsummer
burning effectively controlled common reed [4].

Related categories for Species: Phragmites australis | Common Reed