For 426: Fire Ecology of Sagebrush Steppe
Ecology of Arid and Semi-arid lands Silver sagebrush (Artemisia cana)
Sand sagebrush (Artemisia filifolia)
NOTE: Silver sagebrush is also found on Source: www.sagebrushsea.org dry slopes in southeastern Alaska. Threetip sagebrush
Mountain big sagebrush
Wyoming and basin big sagebrush
Black sagebrush
Source: USGS Wyoming big sagebrush/bluebunch wheatgrass steppe near Boise, Idaho Wyoming big sagebrush/bluebunch wheatgrass steppe near Arco, Idaho Big sagebrush steppe and southern shrublands near Lone Pine, California Stiff sagebrush/Sandberg bluegrass steppe, near Jordan Valley, Oregon Wyoming big sagebrush steppe-Shortgrass prairie ecotone near Casper, Wyo Big sagebrush subspecies
Wyoming big sagebrush (A. t. ssp. wyomingensis)
Basin big sagebrush (A. t. ssp. tridentata)
Mountain big sagebrush (A. tridentata ssp. vaseyana)
Foothill big sagebrush (A. tridentata ssp. xericensis)
“Spiked big sagebrush” (A. tridentata ssp. spiciformis)
“Mountain big sagebrush” (A. tridentata ssp. pauciflora)
(Tart and Winward 1996, 2001) Other common sagebrush vegetation types
Low sagebrush (Artemisia arbuscula)
Threetip sagebrush (Artemisia tripartita)
Black sagebrush (Artemisia nova)
Stiff sagebrush (Artemisia rigida)
Note: Several subspecies have been described for these Artemisia species. Range of fire-free-intervals in pristine sagebrush steppe vegetation
Vegetation type FFI (yrs)
Mtn. Big sagebrush-mtn. Snowberry-fescue Conifer contact zone (7) 15-25 (70) Lower valley, mtn. Foothill 15-40 Wyo. big sagebrush/bluebunch wheatgrass 30-60 Wyo. big sagebrush/Sandberg bluegrass 50->100 Stiff sagebrush/Sandberg bluegrass >100
FFI varies greatly due to factors such as ignition sources, topography, landscape context and fuel continuity. Function of fire in sagebrush steppe vegetation
• Maintenance of sagebrush as a seral vegetation type (ponderosa pine, Douglas-fir, western juniper, pinyon-juniper) • Maintenance of seral vegetation types within sagebrush steppe (grasslands) • Divert the primary productivity of the site from woody species to herbaceous species • Increase the forb component of the community • Establish recruitment conditions for a new cohort of a species (i.e. sagebrush, rabbitbrush species, bitterbrush, early seral grasses) • Nutrient cycling Bluebunch wheatgrass (Pseudoroegneria spicata)
Moderate to high tolerance to fire.
Moderate to low seedling recruitment potential. First-order fire effects: Fire severity
Bluebunch wheatgrass Increasing fire severity resulted in increased fire damage.
Fire damage was limited to tissues in the upper 20 mm of soil.
Photo by J. Kingery (Balatsos 1994) First-order fire effects: Plant phenology
Bluebunch wheatgrass Heat resistance varied with phenological stage: [summer > fall > spring].
Heat resistance varied within a phenological stage due to current climatological conditions.
(Balatsos 1994) Effects of increasing soil moisture on heat flow and plant heat resistance:
- Increases the heat capacity of soil
- Increases the heat conductivity of soil
- Increases the heat movement in soil through vapor flux
- Increases plant activity Great Basin wildrye (Leymus cinereus)
One of the most fire tolerant grasses associated with the sagebrush steppe.
Low seedling recruitment potential.
Suspected of increased recruitment post-burn. Bottlebrush squirrel-tail (Elymus elymoides)
Very fire tolerant species.
High post-fire seedling recruitment potential.
Relatively short-lived plant. Needlegrasses (Acnatherum, Hesperostipa spp.)
Needle-and-thread Moderate to high mortality due to fire.
Moderate to high seedling recruitment potential except for Thurber needlegrass.
Often fill gaps created by fire until other species respond.
Photo by K. Sedivec & W. Barker Sandberg bluegrass (Poa secunda)
Moderate to high mortality rates.
High seedling recruitment potential.
Persists in community under high sagebrush coverage and density.
Photo by C. Johnson Lupine species (Lupinus spp.)
Silky lupine (L. sericeus) High fire tolerance
Increased biomass production post-fire
Often increased density post-fire
High seed production post-fire
Nitrogen fixer Perennial forbs
Applegate’s paintbrush (Castilleja applegatei) Most species respond favorably to fire, however, many wild buckwheat species are fire sensitive.
The paintbrush species are often parasitic.
Many sagebrush steppe perennial forbs decline during juniper woodland encroachment. Seedling recruitment following fire is Mat wild-buckwheat (Eriogonum caespitosum) extremely slow. Antelope bitterbrush (Purshia tridentata) Resprouting antelope bitterbrush (Purshia tridentata) Deer mouse, David Cappaert, www.forestryimages.org Antelope bitterbrush (Purshia tridentata) seedlings from rodent cache Changes in the environment that have significantly altered the historical role of fire in sagebrush steppe vegetation
• Introduction of annual grasses (Cheatgrass, medusahead) The introduction of annual grasses has permanently altered the former role of fire in sagebrush steppe.
Photo by Dale Wade, forestryimages.org Changes in the environment that have significantly altered the historical role of fire in sagebrush steppe vegetation
• Introduction of annual grasses (Cheatgrass, medusahead)
• Changes in levels of herbivory
Pronghorn antelope, William M. Ciesla forestryimages.org Changes in the environment that have significantly altered the historical role of fire in sagebrush steppe vegetation
• Introduction of annual grasses (Cheatgrass, medusahead)
• Changes in levels of herbivory
• Climatic change
Variations in Earth’s average surface temperature over the past 20,000 years
World Health Organization (www.who.int/globalchange/climate/summary/en/) The number of fires by size class in the study region to include the Snake River Plain and Northern Basin and Range Ecoregions.
Size-Class
Decade
3 years of data
1st and 2nd half of data set
Source: Kuchy 2008 Wyoming big sagebrush steppe, southern Idaho First year post-burn Bottlebrush squirrel-tail Great Basin wildrye
Fifth year post-burn Unburned sagebrush island
Fifteenth year post-burn Green rabbitbrush (Chrysothamnus viscidiflorus)
Burn pattern on landscape 1st year post-burn 3rd year post-burn Mountain big sagebrush/Idaho fescue steppe, eastern Idaho Douglas-fir, mountain big sagebrush, eastern Idaho 1st year post-burn 3rd year post-burn 7th year post-burn Post-burn establishment and recovery of the sagebrush stand depends upon:
- The taxa of sagebrush involved
- Continuity of the burned area, related to seed availability
- Post-burn environmental conditions Mountain big sagebrush/ Idaho fescue ht. Owyhee Mountains, Idaho
8th year post-burn
Mountain big sagebrush/ Idaho fescue ht. Beaverhead Range, Idaho
7th year post-burn The use of prescribed fire is limited by the following considerations:
• Disagreement on the optimal sagebrush cover for different multiple-uses • Disagreement on the appropriate size of sagebrush burns • Lack of fine fuels • Low levels of perennial herbs present in the pre-fire community • Short-term effects on some high profile species (bitterbrush, sage grouse) • Potential for biological invasions Prescribed fire in Wyoming big sagebrush/bluebunch wheatgrass Murphy Complex Fire
July 16-Aug. 3, 2007
Total area: 653,100 acres (1020 square miles)
Ignition source: Lightning
This was actually 3 fires: Rowland Fire Elk Mtn. Fire Scotts Creek Fire
Arrows indicate approximate fire ignition points. Source: http://pubs.usgs.gov/of/2008/1214 /pdf/ofr20081214.pdf Burn progression map July 16- August 3, 2007
July 18
July 19 July 20 July 21
July 24
Source: http://pubs.usgs.gov/of/2008/1214 /pdf/ofr20081214.pdf Burn severity map based on remotely sensed data The highest severity fire (orange) was associated with areas that had the highest coverage of big sagebrush.
The lower severity fire (yellow) was associated with areas that had previously burned and were dominated by herbaceous species.
Cheatgrass was common in the northern quarter.
Native species and seeded introduced grasses were common in the southern three quarters.
Source: http://pubs.usgs.gov/of/2008/1214 /pdf/ofr20081214.pdf Wyoming big sagebrush steppe- Pre-burn Murphy Complex Fire Photo taken August 28, 2007, 3 weeks post-burn Source: http://pubs.usgs.gov/of/2008/1214/pdf/ofr20081214.pdf Murphy Complex Fire- Burned/unburned mosaic Photo taken August 28, 2007 Murphy Complex Fire- Unburned (grazed), Burned (ungrazed) Photo taken August 28, 2007 Source: http://pubs.usgs.gov/of/2008/1214/pdf/ofr20081214.pdf Threshold of fire behavior with decreasing fine fuel load.
BehavePlus output: 12% dead fuel moisture
Source: http://pubs.usgs.gov/of/2008/1214/pdf/ofr20081214.pdf At lower dead fuel moistures and higher wind speeds, fire behavior was increasingly determined by sagebrush overstory and less by fine fuel loading.
BehavePlus output: 10% dead fuel moisture
Source: http://pubs.usgs.gov/of/2008/1214/pdf/ofr20081214.pdf Murphy Fire- 2 years post-burn, June 2009
Idaho fescue & bluebunch wheatgrass Idaho fescue & bluebunch wheatgrass
Crested wheatgrass Bottlebrush squirrel-tail Next time
Western juniper woodland-mountain big sagebrush steppe