FIRE CASE STUDIES
SPECIES: Artemisia cana ssp. cana | Plains Silver Sagebrush 



CASE NAME : 
Miles City, Montana 2



SEASON/SEVERITY CLASSIFICATION : 
fall/low intensity, moderate severity


STUDY LOCATION : 
This prescribed burn was conducted in early October of 1979 on the
Livestock and Range Research Station near Miles City, Montana.


PREFIRE VEGETATIVE COMMUNITY : 
Preburn vegetation typical of Northern Great Plains mixed-grass prairie.
Western wheatgrass (Pascopyron smithii) and blue grama (Bouteloua
gracilis) were the predominate grasses.  Other associated species
included threadleaf sedge (Carex filifolia), needle-and-thread (Stipa
comata), green needlegrass (S. viridula), and annual brome grasses
(Bromus spp.).  Plains silver sagebrush was abundant on the site.


TARGET SPECIES PHENOLOGICAL STATE : 
Growth and reproductive stages completed.


SITE DESCRIPTION : 
NO-ENTRY


FIRE DESCRIPTION : 
Prescribed burning using a backfire took place in early October.  Summer
drought had substantially reduced soil moisture throughout the profile.
Fuels ranged from 300 kg/ha in blue grama vegetation to 1000 kg/ha in
western wheatgrass.  Ambient air temperature was 70 degrees Fahrenheit
(21 deg C) and wind speed was less than 5 miles per hour (8 km/hr).


FIRE EFFECTS ON TARGET SPECIES : 
Plains silver sagebrush sustained high mortality following fall burning.
Plants are apparently under more moisture stress as the season
progresses and soils dry out.  Both plant survival and subsequent
regrowth are significantly affected.  Seventy-five percent of the plants
that were totally consumed died; mortalities reached almost 40 percent
in less severly burned plants.  Regrowth of individual plants was
significantly impaired.  Although survivors produced numerous sprouts
per plant, plant heights and coverages were markedly reduced.

Mean growth characteristics for surviving plants are summarized below: 

Fire intensity              # sprouts    height (mm)    canopy index (mm)
________________________________________________________________________
Foliage consumed              10.3          188                341
Twigs and foliage consumed    13.3          188                279
Completely burned              4.2           56                 96

Canopy index = Adding linear intercept values of major and minor aces of
assumed elliptical-shaped regrowth.


FIRE MANAGEMENT IMPLICATIONS : 
Under dry, fall burning conditions, numbers and coverages of plains
silver sagebrush can be drastically reduced.  Most plants cannot survive
high severity fires under these conditions; plants which do survive are
able to sustain only a limited amount of regrowth.  Fall burning
represents an effective means of reducing plains silver sagebrush.



FIRE CASE STUDIES
SPECIES: Artemisia cana ssp. cana | Plains Silver Sagebrush 



CASE NAME : 
Miles City, Montana 1



SEASON/SEVERITY CLASSIFICATION : 
spring/ low intensity, low severity


STUDY LOCATION : 
This prescribed burn was conducted in mid-April 1977 on the Livestock
and Range Research Station near Miles City, Montana.


PREFIRE VEGETATIVE COMMUNITY : 
Preburn vegetation typical of Northern Great Plains mixed-grass prairie.
Western wheatgrass (Pascopyrum smithii) and blue grama (Bouteloua
gracilis) were the predominate grasses.  Other associated species
included threadleaf sedge (Carex filifolia), needle-and-thread (Stipa
comata), green needlegrass (Stipa viridula), and annual brome grasses
(Bromus spp.).  Plains silver sagebrush was abundant on the site.


TARGET SPECIES PHENOLOGICAL STATE : 
Winter dormancy broken; plants just becoming physiologically active.


SITE DESCRIPTION : 
NO-ENTRY


FIRE DESCRIPTION : 
Prescribed burning using a headfire took place shortly after spring runoff in
mid-April.  The soil moisture content was at field capacity.  Fuels ranged
from 300 kg/ha in blue grama vegetation to 1000 kg/ha in western wheatgrass.
The following climatic conditions were reported:  
	Ambient air temperature: 70 degrees F (21 degrees C)
	Wind speed:  < 5 mph (8 km/hr)



FIRE EFFECTS ON TARGET SPECIES : 
Although all plains silver sagebrush plants were top-killed, most survived
and resprouted.  Highest mortality, 33 percent, occurred in those plants
where aerial portions were totally consumed.  Less than 10 percent of the
plants having only the foliage consumed or only the foliage and twigs
consumed died.

Generally, spring burning resulted in a low severity fire.  Apparently the high
moisture content of the soil and the phenological stage of plants at the time
of burning increased recovery ability; plants grew vigorously following
resprouting.  Although individual plants produced low numbers of sprouts, stem
elongation was relatively rapid.  Completely burned plants had grown to 8
inches (20 cm) within 3 months; less severely burned plants reached over 12
inches (30 cm).  Sprouts typically assumed a bushy growth form with dense
foliage.

Mean growth characteristics for surviving plants are summarized below:

                                                         Canopy
Fire intensity            # sprouts      Height(mm)    index (mm)

Foliage consumed             4.5           322           394
Twigs & foliage consumed     3.8           305           424
Completely burned            3.3           216           358

Canopy index = Adding linear intercept values of major and minor axes of
assumed elliptical-shaped regrowth.
      
                                           


FIRE MANAGEMENT IMPLICATIONS : 
Plains silver sagebrush can be enhanced  under moist, spring burning
conditions.  Under these conditions most plants can survive relatively high
fire intensities.  Plants readily resprout and grow vigorously.  Preburn
coverages and heights are rapidly regained. 

In areas where plains silver sagebrush is a highly palatable range species,
prescribed spring burns can be used to maintain and even enhance plant
coverages with little loss of potential sagebrush forage.

Related categories for Species: Artemisia cana ssp. cana | Plains Silver Sagebrush