Climate Change and Wildland Fire

Key points, challenging questions, and a range of adaptation strategies

Key Points: Climate Change

• Climate change is ongoing (overwhelming majority of parks are already at the extreme warm edge of historical conditions –Monahan and Fisichelli 2014)
• Resource responses to ongoing climate change are evident across parks and include measurable responses by glaciers, birds, insects, mammals, and vegetation (Carrara and McGimsey 1981; Moritz et al. 2008; Tingley et al. 2009; Dolanc et al. 2013; Giersch et al. 2015)
• Future projections include both directional changes and multiple uncertainties (Melillo et al. 2014)
  • directional change: warming average temperatures, longer fire seasons
  • uncertainties: magnitude of change in the amount and seasonal timing of precipitation; frequency and duration of extreme events such as drought and heatwaves

Key Points: Fire

• Directional change towards warmer and drier conditions and longer fire seasons is already occurring (Westerling et al. 2006)
• Future conditions may to lead to anomalous fire regimes in many regions (McKenzie et al. 2009, Westerling et al. 2011)
• Climate-mediated changes in plant regeneration after future fires may lead to novel vegetation patterns in parks. For example, fire-intolerant and moisture-demanding trees may be replaced by fire- and drought-tolerant species, and low elevation dry forests may convert to shrublands or grasslands, depending on the magnitude of change in climate and fire (Stephens et al. 2013).

Some questions about climate change and fire to ponder

Where climate change is shifting the fire regime outside the historical range of variability, how should we respond?

Should we attempt to maintain historical conditions, and if so, what approaches are permissible?

Are fuels treatments (e.g., mechanical thinning, prescribed burning) appropriate to decrease the extent and severity of wildfires?

Where forests fail to regenerate after fires, should we practice non-intervention and allow the system to self-sort and reorganize, or should we actively intervene to mitigate climate change effects and encourage native species likely adapted to the changing conditions?

Climate Change Adaptation
Climate change adaptation is a rapidly evolving field of conservation biology and is most effective when it is both 1) intentionally designed and implemented and 2) ‘mainstreamed’ into existing management activities such as fire management (Stein et al. 2014). Adaptation includes a range of potential strategies including striving for persistence of current conditions, non-intervention, and directed transformation towards a specific desired new future (Fig. 1). This range of strategies is a useful conceptual model to explore fire management and consider a full spectrum of potential management options. Persistence strategies attempt to prevent or reverse climate change impacts and change to high-value and irreplaceable resources, whereas non-intervention accepts resource change and directed transformation strategies work to guide resource responses towards desired new conditions. Different approaches may be applied in different locations based on value of the resource and feasibility, such that the full range of strategies may be employed at the landscape level. For example, persistence may be applied for a particularly high-value resource on a small scale, whereas non-intervention or directed transformation may be applied in other areas or across the broader landscape. The intensity of management intervention required to achieve a particular adaptation goal depends on the focal resource’s vulnerability to climate change and may vary with management time horizons and rates of climate change.

Figure 1. Potential adaptation strategy options for park vegetation and fire regimes.

Adaptation strategies will depend on the articulated goals, magnitude of climate change, and availability of management resources. The example objectives and strategies suggested here (Fig. 1) cover a broad range of potential approaches that could be pursued. Management interventions like fuels treatments are not new, but their intentional application in climate change adaptation (Stein et al. 2014) may be very different than in past applications, and warrants discussion. Across the range, firefighter safety, protection of property, and adherence to other laws and policies (e.g., air pollution) remain high priorities. Adaptive management, including monitoring, is a key component of natural resource management and is assumed to be ongoing across adaptation option. Furthermore the preferred adaptation strategy may vary within a park, for example among developed, frontcountry, and backcountry locations.

A persistence strategy aims to maintain the historical fire regime and associated vegetation on the landscape, where feasible. Managers could reduce fuel loads and continuity across the landscape through large-scale prescribed burning and mechanical thinning to moderate fire size and burn severity. Enhancing landscape heterogeneity may reduce the likelihood of very large fires burning major portions of the park within a single season. Restoration of native tree species present prior to the fire, such as through planting or broadcast seeding of species could slow the rate of forest decline and prolong the persistence of tree cover in desired areas.

A non-intervention strategy aims at allowing the fire regime and ecosystems to respond to climate without intense intervention intended to direct the system towards specific conditions. As possible, the fire regime and ecosystem composition, structure, and function responses will be allowed to evolve autonomously.

A directed transformation strategy attempts, where feasible, to facilitate the conversion of the landscape to specific future desired conditions, for example identified tree species, forest types, and stand structure and density commensurate with warmer and drier conditions and more frequent fires.

References

Carrara, P. E., and R. G. McGimsey. 1981. The late-neoglacial histories of the Agassiz and Jackson glaciers, Glacier National Park, Montana. Arctic and Alpine Research:183-196.

Dolanc, C. R., J. H. Thorne, and H. D. Safford. 2013. Widespread shifts in the demographic structure of subalpine forests in the Sierra Nevada, California, 1934 to 2007. Global Ecology and Biogeography 22:264-276.

Giersch, J. J., S. Jordan, F. Luikart, L. A. Jones, F. R. Hauer, and C. C. Muhlfeld. 2015. Climate-induced range contraction of a rare alpine aquatic invertebrate. Freshwater Science DOI: 10.1086/679490.

McKenzie, D., D. L. Peterson, and J. J. Littell. 2009. Global warming and stress complexes in forests of western North America. Developments in Environmental Science 8:319-337.

Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W. Yohe, Eds., 2014: Climate Change Impacts in the United States: The Third National Climate Assessment. U.S. Global Change Research Program, 841 pp. doi:10.7930/J0Z31WJ2.

Monahan, W. B., and N. A. Fisichelli. 2014. Climate exposure of US national parks in a new era of change. PLoS ONE 9(7):e101302. doi:10.1371/journal.pone. 0101302.

Moritz, C., J. L. Patton, C. J. Conroy, J. L. Parra, G. C. White, and S. R. Beissinger. 2008. Impact of a century of climate change on small-mammal communities in Yosemite National Park, USA. Science 322:261-264.

Stephens, S. L., J. K. Agee, P. Z. Fule, M. P. North, W. H. Romme, T. W. Swetnam, and M. G. Turner. 2013. Managing forests and fire in changing climates. Science (New York, N.Y.) 342:41-42.

Stein, B. A., P. Glick, N. A. Edelson, and A. Staudt (eds.). 2014. Climate-Smart Conservation: Putting Adaptation Principles into Practice. National Wildlife Federation. Washington, D.C.

Tingley, M. W., W. B. Monahan, S. R. Beissinger, and C. Moritz. 2009. Birds track their Grinnellian niche through a century of climate change. Proceedings of the National Academy of Sciences 106:19637-19643.

Westerling, A. L., H. G. Hidalgo, D. R. Cayan, and T. W. Swetnam. 2006. Warming and earlier spring increase western US forest wildfire activity. Science 313:940-943.

Westerling, A. L., M. G. Turner, E. A. Smithwick, W. H. Romme, and M. G. Ryan. 2011. Continued warming could transform Greater Yellowstone fire regimes by mid-21st century. Proceedings of the National Academy of Sciences 108:13165-13170.