Potential Effects of Disturbance Types and Environmental Variability on Sagebrush-Steppe Community Dynamics

摘要

While fire is widely recognized as an important factor shaping sagebrush (Artemisia spp.) ecosystems, little is known about the role other natural events play in these systems. Using a state-and-transition modeling framework in conjunction with the scientific literature and data for climate (temperature, precipitation, and snow), soils (soil surveys and ecological site descriptions), and modern fire occurrence records, we explored how fire and various other natural events might shape sagebrush ecosystems in eastern Oregon, USA, and whether those events could affect fire rotation. Model results suggested other disturbance events were important in shaping all but the most productive sagebrush communities and influenced fire rotation in drier sagebrush communities. Insects and pronghorn browsing may have been as important as fire in shaping sagebrush-steppe landscapes with freezekill and snow mold locally important. Our study also demonstrated the use of climate, soils, ecological site, and fire occurrence data to derive probabilities of several natural events, providing a more objective approach to estimating reference conditions.