FIRE CASE STUDIES
SPECIES: Bromus japonicus | Japanese Brome 



CASE NAME : 
Prescribed Fire in Badlands National Park

REFERENCES : 
Whisenant, S. G. 1985 [69]
Whisenant, S. G. 1990 [71]
Whisenant, S. G.; Bulsiewicz, W. R. 1986 [72]
Whisenant, S. G.; Uresk, D. W. 1990 [74]


SEASON/SEVERITY CLASSIFICATION : 
Spring/Severity not measured


STUDY LOCATION : 
The study area was in Badlands National Park in south-central South Dakota.


PREFIRE VEGETATIVE COMMUNITY : 
The study was conducted in a stand of native shortgrass prairie in good
condition.  Japanese brome (Bromus japonicus) and western wheatgrass
(Pascopyrum smithii) codominated the site.  Green needlegrass (Stipa
viridula), sand dropseed (Sporobolus cryptandrus), threadleaf sedge
(Carex filifolia), blue grama (Bouteloua gracilis), and buffalograss
(Buchloe dactyloides) were minor components of the community.  Japanese
brome tiller density averaged 1,500 per square meter; western wheatgrass
tiller density averaged 273 per square meter.


TARGET SPECIES PHENOLOGICAL STATE : 
Japanese brome seedlings were 1 to 2 inches (3-5 cm) tall when the April
fires were set, and 3 to 4 inches (8-10 cm) tall when the May fires were
set.


SITE DESCRIPTION : 
The mean growing season in the Park is 126 days.  Annual precipitation
is approximately 384 millimeters, 303 of which falls during the growing
season.  Average temperature is 47 degrees Fahrenheit (8.3 deg C), with
temperatures rising to 100 degrees Fahrenheit (38 deg C) in summer and
dropping to -20 degrees Fahrenheit (-29 deg C) in winter.  Summer and
fall relative humidity has a wide diurnal variation, ranging from 85
percent in morning to 40 percent by afternoon.  Precipitation from
October 1983 to July 1984 (the first year of the study) was above
average, with of most of it occurring in fall.  Precipitation from
October 1984 to July 1985 (the second year of the study) was 61 percent
of normal.  Soil at the study site is Larvie silty clay (fine,
montmorillonitic, mesic, vertic Camborthid).

The study site was relatively undisturbed.  It had never been cultivated
and had not been burned or grazed by domestic livestock for at least 25
years.  White-tailed deer, pronghorn, bison, and Rocky Mountain bighorn
sheep reside in the Park, but grazing effects were not apparent at the
study site.


FIRE DESCRIPTION : 
Fire treatments were:  (1) unburned, (2) burned in April 1983, (3)
burned in May 1984, (4) burned in April 1983 and April 1984, (5) burned
in May 1983 and May 1984, (6) clipped in April 1983, (7) clipped in May
1983, (8) atrazine application in September 1983, (9) burned in April
1983 with atrazine application in September 1983, and (10) burned in
April 1984.

Environmental and fuel variables during the fires were as follows:


                  Ambient        Wind     Relative     Fuel      Fine
Date Burned     Temperature     Speed     Humidity   Moisture    Fuels
                  (deg C)       (km/hr)   _________%________   (g/sq m)

20 April 1983       22            6-9        40         18        211
19 May 1983         14           19-23       78         38        298
16 April 1984       14            5-23       43         28        276
9 May 1984          16           13-16       56         35        272  


FIRE EFFECTS ON TARGET SPECIES : 
Japanese brome tiller density and standing crop were significantly
reduced the first year after the 1984 fires.  Tiller density and
standing crop were not significantly reduced the second postfire year.
Burning resulted in greater reductions than did clipping, indicating
that mortality resulted from heat rather than simply foliage removal.
Atrazine applied as a preemergent herbicide significantly reduced
Japanese brome density.

In July 1984, Japanese brome density and standing crop were as follows:

Treatment             Treatment Number         Density        Standing Crop
                                            (tillers/sq m)      (g/sq m)
___________________________________________________________________________
Control vs.                  1                 2,617             14.8
1983 fire                    2                 2,028 NS          19.9 NS    

Control vs.                  1                 2,617             14.8
1984 fire                    3,10                 23**            0.7*

Control vs.                  1                 2,617             14.8 
1983 & 1984 fires            4,5                 580**            4.7*

1984 fire vs.                3,10                 23              0.7
1983 & 1984 fires            4,5                 580**            4.7 NS

Control vs.                  1                 2,617             14.8 
atrazine application         8                    19**            0.0*

1983 clipping vs.            6,7               3,250             24.7
1983 fire                    2                 2,028*            19.9 NS

1983 fire vs.                2                 2,028             19.9
1984 fire                    3,10                 23**            0.7** 

1983 fire followed by     
  atrazine application vs.    9                 19                1.5
atrazine application          8                 77 NS             0.0 NS

atrazine application vs.      8                 19                0.0
1984 fire                     3,10              23 NS             0.7 NS
___________________________________________________________________________
NS means contrast is not significant; * means P<0.05;
** means P<0.01

Japanese brome densities in the spring were positively correlated with
litter weight and autumn precipitation.  As precipitation decreased,
litter became more important.  Burning reduced seed production for at
least three growing seasons.  Seed production in 1984 and 1985 was
greatest in controls and lowest in recently burned plots.  In 1986, seed
production was reduced in plots burned in 1984 but not in untreated
plots or those burned in 1983.  

Litter seedbanks were reduced when precipitation was below normal.  The
litter seedbank was reduced drastically after the combination of drought
and fire in 1985.  Reduction in the litter seedbanks on burned sites
lasted for 3 years.  The soil seedbank was also reduced for 3 years, but
the reduction was less drastic.

Japanese brome seedling density and seedbank reserves, measured in July,
were as follows:

_______________________________________________________________________________
Seed production (per sq m)    Control    Burned April 1983    Burned April 1984
   1983                       73,160 a        1,620 b             67,815 a
   1984                       94,212 a       46,644 b                368 c
   1985                        1,410 a          785 b                375 c
   1986                       31,584 a       29,911 a             12,208 b
   1987                       30,416 a       27,897 a             38,157 a

Litter seedbank (per sq m)
   1984                       12,460 a       11,775 a                700 b
   1985                          187 a          112 b                 18 c
   1986                        6,712 a          263 b                 89 b
   1987                        7,914 a          869 b                475 b

Surface soil seedbank (per sq m)
   1984                       11,852 a       10,760 a             11,512 a 
   1985                        7,859 a        6,923 ab             5,754 b
   1986                        4,587 a        3,712 a              2,251 b
   1987                        6,810 a        2,861 b              2,551 b 

Seedling density (per sq m), measured in April
   1983                        2,738 a        2,299 a              2,516 a
   1984                        2,287 a        2,417 a              2,381 a 
   1985                          578 a          554 a                 72 b
   1986                          990 a          523 b                 65 c
   1987                        2,114 a        1,847 a              1,710 a
______________________________________________________________________________
Means within a row followed by the same letter are not significantly
different from each other at P=0.05


FIRE MANAGEMENT IMPLICATIONS : 
Fire that reduces litter accumulations reduces the next generation of
Japanese brome.  Carryover of Japanese brome in the seedbank is usually
sufficient to establish subsequent generations.  As water becomes more
limiting, litter becomes increasingly important in determining the size
of Japanese brome populations.

Related categories for Species: Bromus japonicus | Japanese Brome