Prescribed Fire-use treatments
Fire and grazing play an important role in managed rangeland ecosystems. These disturbances interact to shape plant communities and outcomes for rangeland biodiversity and livestock production. However, managers have a limited toolbox to reach vegetation management goals in shrub-steppe ecosystems. It is commonly assumed that deferring grazing for up to two growing seasons after a fire is necessary to ensure plant community recovery. We report on a 4-year long replicated experiment comparing the effects of season of fire (spring or fall) and sheep grazing deferment on sagebrush-steppe rangelands in east Idaho, USA. Deferment treatments included either no grazing for one or two growing seasons after fire, or no deferment, in which domestic sheep returned in the season after fire. We found no evidence that grazing deferment affected plant community composition in any plots compared to no grazing deferment, but deferred areas did have more litter relative to grazed areas 4 years after the fire. Burn treatment had a consistent effect on plant communities. One year after fire, spring and fall burned plots had 24 and 30% reductions in native shrub cover, respectively. After 4 years, fall and spring burned areas had moderate, statistically significant (14 and 9%, respectively) reductions in litter. Burned areas had less than 6% increases in perennial native grass cover, but no significant increases in invasive plants. The effects of fire and grazing management tools is context-dependent across climatic gradients in the sagebrush biome. At our study site, prescribed fire seasonality and grazing deferment have important economic but relatively moderate ecological implications.