FIRE EFFECTS
SPECIES: Poa compressa | Canada Bluegrass 



IMMEDIATE FIRE EFFECT ON PLANT : 
Plant phenological stage at time of burning greatly influences fire
damage to herbaceous plants.  In general, as new foliage of perennial
grasses reaches full development major food reserves have been depleted,
so that plants are injured most from fires occurring at this time [5].
Late spring fires, after plants have been growing for about a month or
more, appear to be the most damaging to Canada bluegrass.


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Season of burning and frequency of burning greatly influence Canada
bluegrass postfire recovery.  Dormant-season fires favor Canada
bluegrass, and biomass and density may increase during postfire year 1.
Late spring burning, when plants are actively growing, reduces biomass
and density during postfire year 1, but biomass and density may return
to preburn levels within 1 or 2 years.  Thus Canada bluegrass often
recovers within 1 or 2 years after a single late spring fire, but
density and biomass are progressively reduced if burned annually or
biennially in late spring.

In abandoned fields in southern Wisconsin, Canada bluegrass flowering
stem density was reduced 50 percent when burned annually in May for 5
years.  Conversely, flowering stem density increased 170 and 440
percent following 5 years of annual burning in March or October,
respectively [4].  A similar study in southern Wisconsin found that 3
years of annual burning in mid-May reduced Canada and Kentucky bluegrass
flowering stem density by 70 percent, while late March or early April
burning had little affect on flowering [14].

In a reconstructed tallgrass prairie in Illinois, bluegrass (Poa
compressa and P. pratensis combined) percent relative biomass decreased
as fire frequency increased in two communities as follows [11]:

                               Burning Treatment*  
                 not burned     burned twice    burned      burned
                                               3 times     4 times
Community type
big bluestem        23.4**           18.3         4.6          0
indiangrass         18.6             15.9         3.3          0

*not burned = unburned for 19 years
 burned twice = burned Feb. 28, 1952 and April 16, 1959
 burned three times = burned Feb. 28, 1952; April 16, 1959; and May 2, 1961 
 burned four times = burned Feb. 28, 1952; April 16, 1959; May 2, 1961; and
                     May 10, 1962

**sampled at the end of the 1962 growing season

In oak (Quercus spp.) woods and goldenrod (Solidago spp.) fields
accidently burned between April 6 and May 2 in south-central New York,
Canada bluegrass frequency increased from 6 to 17 percent and 56 to 81
percent, respectively, 10 to 26 months after burning [28].

After early May prescribed burning in seral brushfields in northern
Idaho, Canada bluegrass recovered rapidly on lightly burned plots.
During the first postfire growing season, it produced the bulk of grass
biomass on lightly burned plots, which was 135 pounds per acre (151
kg/ha).  In comparison, grass production on heavily burned and control
plots averaged only 0.7 and 10.2 pounds per acre (0.8 and 11.4 kg/ha),
respectively [17].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
Annual or biennial late spring burning can be used to control Canada
bluegrass and promote the growth of warm-season grasses in the Midwest.
The timing of burning is critical and should take place just prior to
the resumption of warm-season grass growth.  Such burning favors
warm-season grasses because they are dormant at the time of burning.
Conversely, cool-season species like Canada bluegrass are harmed by late
spring fire because they resume growth in the early spring and are thus
actively growing at the time of burning [15].

Related categories for Species: Poa compressa | Canada Bluegrass