• CASE NAME
• SEASON/SEVERITY CLASSIFICATION
• STUDY LOCATION
• PREFIRE VEGETATIVE COMMUNITY
• TARGET SPECIES PHENOLOGICAL STATE
• SITE DESCRIPTION
• FIRE DESCRIPTION
• FIRE EFFECTS ON TARGET SPECIES
• FIRE MANAGEMENT IMPLICATIONS

CASE NAME:

Wyoming big sagebrush response to burning in a Wyoming big sagebrush/bluebunch wheatgrass habitat type

REFERENCE:

Clifton, N. A. 1981 [31]

SEASON/SEVERITY CLASSIFICATION:

fall (Sept. 27 through Oct. 1, 1978)/light severity

STUDY LOCATION:

The study area is 25 miles (40 km) north of Shoshone, Idaho, on the Shoshone District, BLM.

PREFIRE VEGETATIVE COMMUNITY:

The community was a Wyoming big sagebrush/bluebunch wheatgrass (Artemisia tridentata spp. wyomingensis/Pseudoroegneria spicata) habitat with large amounts of Thurber needlegrass (Achnatherum thurberianum). Western wheatgrass (Pascopyrum smithii), Sandberg bluegrass (Poa secunda), and low sagebrush (A. longiloba) were common. Two exotic grasses were present in low numbers: cheatgrass (Bromus tectorum) coverage was less than 2%, and Japanese brome (B. japonicus) coverage was less than 1%. Bare ground coverage was 47%; litter coverage was 36%.

SITE DESCRIPTION:

Use: The study site lies within a grazing allotment used by domestic sheep in spring. Nonuse averaged 70% of the authorized AUM's prior to the study, and this grazing pattern continued throughout the study. The area is also managed for sage grouse.

Landscape characteristics: Elevation is 5,000 feet (1524 m). Topography is undulating with rocky outcrops. Soils are fine clays and clayey loams of basaltic or rhyolitic parent material. Soil permeability is low. Average annual precipitation is 11 inches (280 mm), with the majority falling from November through January. Average annual temperature is 45 degrees Fahrenheit (7 ^oC), with average annual maximum and minimums of 100 degrees Fahrenheit (38 ^oC) and 0 degrees Fahrenheit (-14 ^oC), respectively. Frost-free period is about 3 months. Prevailing winds are from the west.

Climate during study period: The 2 months prior to the late September burning had abnormally high precipitation. The winter and late spring following burning were abnormally dry; otherwise, precipitation at postfire year 1 was in normal range. In postfire year 2, precipitation was well above normal.

FIRE DESCRIPTION:

Management objectives were to reduce Wyoming big sagebrush cover; increase herbaceous forage; improve habitat quality for sage grouse and other wildlife by creating a mosaic of burned and unburned patches with at least 10% of the area burned; and to reduce wildfire hazard. The fire prescription called for strip headfires under the following conditions:

fine fuel moisture  13-30%
relative humidity   20-45%
windspeed           5-30 miles/h (8-48 km/h)
temperature         50-85oF (10-30oC)

fine fuel moisture  not given
relative humidity   19-36%
windspeed           3-25 miles/h (4.8-40 km/h)
temperature         64-85oF (18-30oC)

FIRE EFFECTS ON TARGET SPECIES:

Coverage of Wyoming big sagebrush was significantly (p < 0.05) less on burned plots than on unburned control plots. Postfire density of live Wyoming big sagebrush plants was about 500% greater on control plots:

		                -----------Burned----------   
		                postfire yr 1  postfire yr 2       
live density (plants/ha)   2000           2250            
dead density (plants/ha)   11250          1105             
cover (%)                  0.79           1.09               

                                      
                           -----------Control-----------
				    postfire yr 1   postfire yr 2
live density (plants/ha)   13950           13500   	
dead density (plants/ha)   4500            4400 
cover (%)	                17.37           19.35

FIRE MANAGEMENT IMPLICATIONS:

The prescribed fire met or nearly met management objectives. The study site was typical of many Wyoming big sagebrush habitats in that bare ground was plentiful and fuels somewhat sparse, but the study area had enough fine fuels to carry a patchy fire. Target percentage (at least 10%) of the study area to be burnt was exceeded, and Wyoming big sagebrush was reduced. Overall production of herbaceous forage increased, although production of Sandberg bluegrass and Thurber needlegrass declined after fire. At postfire year 1, bluebunch wheatgrass yield was 330% greater on burned plots compared to unburned plots. Exotic grasses were present in low numbers before fire, and prescribed burning did not result in attendant increases in the exotics.

During the 1st summer after fire, 110 individual sage grouse including brood were observed using the mosaic created by burning.

Domestic sheep were put on the study site 3 weeks after burning. Although deferment of grazing for 1 to 2 years after burning is usually recommended in Wyoming big sagebrush habitats, Clifton [31] suggested that the short-duration, light use of the area did no major damage to the newly burned rangeland.

Related categories for SPECIES: Artemisia tridentata ssp. wyomingensis | Wyoming Big Sagebrush