FIRE EFFECTS
SPECIES: Lolium multiflorum | Italian Ryegrass 



IMMEDIATE FIRE EFFECT ON PLANT : 
Fire probably kills Italian ryegrass.  Seeds may survive fire.


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Italian ryegrass generally decreases after fire.  A California annual
grassland site on the coastal foothills near Berkeley burned in July.
Forbs generally increased and grasses decreased in the first growing
season after the fire.  Burned sites produced lower Italian ryegrass
yields than unburned sites.  Italian ryegrass height was significantly
lower the year after the fire on burned sites than unburned sites [30]:

				Average Height (Inches)
			Dec 1		Feb 20		May 1

Burned	        	2.4		3.5		13.7
Unburned		3.7		6.9		16.1

A March 5 fire on a Georgia old field resulted in a significant (P<0.05)
decrease in Italian ryegrass yield.  The control produced 98.4 grams per
square meter and the burned area produced 47.4 grams per square meter in
the summer following the fire [46].

Italian ryegrass was present (0.1% cover) after a July fire in San
Bernardino County, California.  The prefire community, dominated by
brittle bush (Encelia farinosa), had not burned for 21 years and did not
contain Italian ryegrass [65].  The seed source for the postfire
population of Italian ryegrass was not described.


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
For years Italian ryegrass has been the most commonly used species for
controlling erosion on burned chaparral sites, especially in northern
California and coastal areas.  Seed is usually broadcast aerially in the
fall following the fire but preceding the winter rains.  Italian
ryegrass has reliable germination, rapid early growth, a short life
span, abundant fibrous roots, inexpensive seed, and broad site
adaptability [57].  However, the wisdom of ryegrass seeding has been
questioned for decades, and recent literature indicates that postfire
seeding of Italian ryegrass may cause more harm than good.  The purpose
of the seeding is to control erosion which is often severe during winter
rains on steep slopes in California.  However, studies have shown that
the seeding is not effective at controlling erosion the first year and
may even increase erosion in succeeding years.  In addition, Italian
ryegrass outcompetes the recovering native vegetation and may increase
the fire hazard.  The controversy is reviewed by Barro and Conard [2]
and Gautier [19], and is summarized here.

Several studies have shown that erosion was not controlled, and even
increased, with Italian ryegrass seeding [23,57].  Erosion was greater
on seeded sites than on unseeded sites of the 1985 Las Pilitas Fire in
the Santa Lucia Range, Monterey County, California.  Researchers found
that pocket gopher activity was greater on seeded sites and was the
cause of the increased erosion [57].  Nadkarni and Odion [45] suggest
that as Italian ryegrass declines, vegetative cover on seeded sites may
actually be less than cover on unseeded sites, and thus erosion may be
greater.  After the Marble-Cone Fire in the Santa Lucia Range, heavy
rains in January washed 1.2 to 3.1 inches (3-8 cm) of surface soil from
slopes greater than 20 percent.  The erosion occurred before seeded
Italian ryegrass had formed an effective cover [23].  Winter rains are
often not sufficient for Italian ryegrass germination until December or
January when the daily temperature is too cool for adequate growth.  A
wetting agent applied to the soil surface during the seeding may
encourage earlier germination [11].

Seeding Italian ryegrass may have long-term detrimental effects on
chaparral communities because Italian ryegrass interferes with native
species regeneration.  On sites seeded with Italian ryegrass, the
seedbank becomes depleted of fire-following species because they may
germinate but do not establish [45].  After Italian ryegrass dies out it
often leaves behind a thinned out chaparral with considerably fewer
nonsprouting species such as wedgeleaf ceanothus (Ceanothus cuneatus)
than in areas without Italian ryegrass seeding [7].  In seeded plots in
burned chaparral in the Santa Ynez Mountains, California, there was a 40
percent reduction in species diversity compared with unseeded plots.
The predominant native Amador rushrose (Helianthemum scoparium) was less
dense in the seeded treatment, and two other species usually found
(hoaryleaf ceanothus [C. crassifolius] and common turricula [Turricula
parryi]) were absent from the seeded plots.  The fire-annual yellow
whisperingbells (Emmenanthe penduliflora) had over 50 percent less cover
on seeded plots than unseeded plots at one site in southern California
[5].  The first year following the Las Pilitas Fire in the Santa Lucia
Mountains, Italian ryegrass interfered with the regeneration of lupine
(Lupinus spp.), lotus (Lotus spp.), and chamise (Adenostoma
fasciculatum) [57].  One year after fire in chaparral in the Santa
Monica Mountains, California, Italian ryegrass cover was negatively
correlated with herbacous species and with island ceanothus (Ceanothus
megacarpus) [9].  Because of the ability of Italian ryegrass to compete
well with woody species, it is recommended for seeding of fire breaks
within chaparral communities [22].

Italian ryegrass restricts tree regeneration where seeded on burned
forested sites.  Italian ryegrass interfered with the regeneration of
sugar pine (Pinus lambertiana) and Coulter pine (P. coulteri) seedlings
after the Marble-Cone Fire [23].  Two years after fire on the Stanislaus
National Forest, California, postfire regeneration of ponderosa pine (P.
ponderosa) was absent where Italian ryegrass cover was greater than 40
percent [9].  

An additional detrimental effect of postfire seeding is that dense
stands of Italian ryegrass burn readily, and early recurring fire is
destructive to regenerating shrubs [67].  The natural fire interval in
chaparral is about 10 to 100 years [69].  An August 1979 fire on Otay
Mountain, San Diego County, California, was seeded with Italian
ryegrass.  The year had near-record precipitation so Italian ryegrass
growth was exceptional.  In July another fire occurred in the areas
seeded with Italian ryegrass.  This second fire killed nearly all
seedlings of explorer's bush (C. oliganthus), and chamise was reduced by
up to 97 percent.  Mission manzanita (Xylococcus bicolor), a postfire
sprouter, suffered substantial mortality.  It is believed that such an
early return fire causes drastic shifts in species composition [67].
In the Santa Ynez Mountains a July fire burned into seeded areas but not
unseeded areas 2 years after the original fire [45].

After fire in grasslands containing Italian ryegrass, grazing should be
delayed or reduced to allow Italian ryegrass to recover [30].

Related categories for Species: Lolium multiflorum | Italian Ryegrass