Effect of Livestock Grazing and Fire History on Fuel Load in Sagebrush-Steppe Rangelands

Abstract

Managers face an important and challenging task of measuring, modeling, and managing wildfire risk. We examined the effect of livestock grazing and previous wildfire events on fuel load in southeastern Idaho as part of a wildfire risk-livestock interaction study. Fuel load was estimated using ordinal fuel load classes at 128 sample sites stratified by current livestock grazing and documented wildfire occurrence (1939-2000). Fifty-nine percent of previous wildfire sites (n = 46) had a documented fire within the past 2 years. Livestock grazing was the most effective means to reduce fuel load (P < 0.0005) compared to recent wildfire (P < 0.05) and livestock grazing with previous wildfire (P < 0.05) at higher stocking rates (1 AU / 19.8ha). Fire, on the other hand, was more effective compared to lower stocking rates (1 AU/ 34.6ha). When proper consideration is given to other ecological effects, livestock grazing provides a viable management tool for fuel load reduction that avoids the negative effect of extreme fire intensity where fuel load is high.