Due to its broad distribution, Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis) is one of the most important plants to sage-grouse (Centrocercus spp.) and other sagebrush obligates. The extent of Wyoming big sagebrush communities has been greatly reduced since European-American settlement and is likely to be further reduced due to the proliferation of nonnative, invasive annual grasses, wildfire, climate changes, and other factors. Invaded communities can experience longer fire seasons and increased fire frequency, size, spread rate, and duration such that Wyoming big sagebrush cannot reestablish, a grass/fire cycle establishes, and Wyoming big sagebrush communities convert to nonnative annual grasslands. The Fire Effects Information System (FEIS, www.feis-crs.org/feis/) offers two new syntheses on Wyoming big sagebrush. A Species Review that describes the biology, habitat, regeneration characteristics, and fire ecology of Wyoming big sagebrush, and a Fire Regime Synthesis that describes the frequency, size, pattern, and severity of fires in Wyoming big sagebrush-basin big sagebrush (A. t. subsp. tridentata) ecosystems before and after European-American settlement. These publications synthesize and analyze evidence from 1,000s of publications to help land managers quickly find the most relevant and useful research on the fire history, fire ecology, and postfire recovery of this subspecies.
Results/Conclusions
Available evidence suggests that presettlement wildfires in Wyoming big sagebrush ecosystems were stand-replacing, mostly small, and often formed a mosaic of burned and unburned patches. Because big sagebrush ecosystems occur over a productivity gradient driven by soil moisture and temperature regimes, fire frequency likely changed across the gradient, with more frequent fire on more productive sites that supported more continuous fine fuels. Wyoming big sagebrush is easily killed by fire and postfire establishment depends on seeds in the soil or from nearby unburned plants. Postfire recovery depends on interactions among several variables, including prefire vegetation; soil moisture and temperature regimes; fire characteristics; and postfire land uses. Our analyses of 112 burned sites examined in 24 studies found that postfire recovery of Wyoming big sagebrush is generally slow but variable. No sites were fully recovered within 66 years since fire, although a few neared recovery. Ecosystems on warm, dry sites are less resilient to fire and less resistant to postfire invasion by nonnative annual grasses than those on cooler, moister sites; consequently, they are likely to recover more slowly. Because of potentially slow recovery, prescribed fire is not recommended in Wyoming big sagebrush communities likely to convert to nonnative annual grasses.