Researchers are increasingly examining patterns and drivers of post-fire forest recovery amid growing concern that climate change and intensifying fires will trigger dramatic transformations in forests. Diminished seed availability and post-fire drought have emerged as key constraints on conifer recruitment in multiple regions. However, the spatial and temporal extents to which climatic anomalies, which may be linked across vast distances through climatic teleconnections, shape patterns of post-fire recovery remain largely unexplored. Here, we identify the dominant mode of climatic water deficit variability across the Interior West—a north-south climatic dipole—and examine its influence on annual recruitment rates and longer-term cumulative probabilities of recruitment. Specifically, we use annually-resolved establishment models from post-fire field data in the Northern Rockies (NR) and Southwest (SW) as well as Forest Inventory and Analysis data from 989 burned plots across the Interior West to quantify the influence of the climatic dipole, while accounting for other climatic and stand-level factors.
Results/Conclusions
We show that annual post-fire ponderosa recruitment rates in the NR and the SW track the strength and prevalence of the dipole. This indicates that divergent recruitment trajectories may be triggered concurrently across large spatial scales: favorable conditions in the SW can correspond to drought in the NR that inhibits ponderosa establishment. The imprint of this climatic dipole may be manifest for decades post-fire, as evidenced by dampened longer-term likelihoods of juvenile ponderosa presence in regions that experienced post-fire drought. For ponderosa, these temporal climatic drivers are more influential on longer-term recruitment dynamics than broad-scale spatial climatic gradients. By contrast, juvenile Douglas-fir presence is less contingent on post-fire conditions and is strongly favored by local live canopy cover, which affords microclimate buffering from unfavorable macroclimate conditions. These findings underscore the importance of linked multi-scalar climatic variability in shaping cross-regional patterns of recovery at multiple timeframes, and have implications for predicting range dynamics as well as where and when post-fire recovery may be robust or, conversely, limited.