Applying conservation decision tools to forests: Fire management in the Sierra Nevada

Background/Question/Methods

Changing climates are forcing forest resource managers to rethink historical objectives for managing reserves in pristine states and restoring historical disturbance regimes. If looking to the past is no longer a guide for future forest management, then what are the potential guideposts to plan and evaluate success of public lands management? We initiated an consortium approach to research, assembling a team of researchers and managers from the National Park Service, US Forest Service, US Geological Survey and the University of California, to assess the vulnerability of Southern Sierra Nevada forests to climate change and fire. Our research questions were: what forest types are most vulnerable to climate- and fire-driven change; when do these types become vulnerable, and where do they become vulnerable first? Conversely, we asked what, and where do we find, forests least vulnerable to change? We used a simple bioclimatic envelope approach using a hydroclimatic downscale model for two future climate scenarios to assess vulnerability, but not predict future distribution. We then applied a simple fire simulation model to a small portion of the landscape to test for how well different approaches to fire management result in minimizing the risk of land cover conversion through high intensity fire.

Results/Conclusions

We find that iconic resources such as the giant sequoia, lower slope oak woodlands, and high elevation conifer forests are projected as highly vulnerable by models that project a warmer drier future, but not as much by models that project a warmer future that is not drier than current conditions. Further, we find strongly divergent vulnerabilities of these forest types across land ownership (National Parks versus US Forest Service lands). Examining potential magnitude of future change suggests that the region is likely to be characterized by strong upslope shifting of open grassland, chaparral and hardwood types. A simple fire simulation evaluated four fire management strategies (business as usual; resist change; foster orderly change; protect vital resources) across four different scenarios of future climate and fire frequency. None of these strategies was uniformly successful in protecting critical resources across the range of future conditions examined. This failure to protect valued resources is driven by current management constraints on the amount of management available to resource managers. The result is likely to be continued increases in the observed frequency of large landscape changing fire in the region.