In sagebrush-dominated shrublands of western North America, warmer temperatures coupled with annual grass invasions are increasing the frequency and extent of wildfires, and land managers are implementing prescribed burn treatments to reduce woody fuel loads. Post-fire big sagebrush (Artemisia tridentata) recovery rates are unpredictable and many recent fires have resulted in the apparent loss of sagebrush habitat. There is a pressing need to identify management strategies that can promote post-fire sagebrush recovery, requiring an improved understanding of the factors influencing sagebrush establishment following high-severity wildfire. In this study, we combined dendrochronological methods, repeated vegetation surveys, and detailed soil environmental measurements from a regional network of experimental prescribed fires to examine the temporal patterns of post-fire big sagebrush establishment across climatic gradients in the Great Basin. We quantified natural big sagebrush regeneration in small prescribed burns with residual post-fire seed sources to ask: (1) what are the climatic conditions that promote sagebrush recruitment post-fire? And (2) how is post-fire sagebrush recovery influenced by the frequency of climatically favorable opportunities for establishment?
Results/Conclusions
We found that post-fire sagebrush establishment was highly episodic, with pulses of recruitment in years with wet springs. Sites with more favorable environmental conditions had more rapid post-fire sagebrush recovery, yet abundant establishment in a single year was more predictive of long-term cover and density than average site conditions. Given favorable soil environmental conditions and seed availability, establishment probability remained high for up to five years after fire. These results suggest that, even in the interior of larger fires where sagebrush recovery is often limited by lack of viable seeds, the window of opportunity for restoration efforts that include post-fire seeding or planting may be longer than previously thought. This is an especially important insight for burns in drier areas, where it is less probable that ephemeral periods of seed availability will coincide with favorable weather conditions for successful sagebrush establishment. In those locations, an adaptive management approach that includes the option of repeated seeding will likely increase the probability of sagebrush recovery.