Long-term impacts of climate changes on wildlife habitat in Glacier National Park, Montana: Simulating complex interactions among climate, vegetation, and wildfire

Background/Question/Methods

Predicted climate changes threaten to alter the geographic distribution of many habitats and their species compositions. Of great importance to species and habitat conservation are local-to-regional climate changes and related effects on vegetation and disturbance regimes. In many areas of the western U.S., these effects may include prolonged droughts, changes in vegetation composition, structure, and succession, longer wildfire seasons, and lower fuel moistures that may, in turn, foster more frequent, larger, and more severe wildfires. Given these changes, analogs from current or recent past conditions may be inadequate guides for design of conservation and management programs. Simulation experiments offer a method for exploring potential impacts of climate changes on landscapes, and implications for species and habitat. We used Fire-BGCv2, a mechanistic vegetation dynamics model, to examine ecological responses to climatic changes and disturbance regimes within forested landscapes at Glacier National Park, Montana. We combined Fire-BGCv2 with a habitat index model to evaluate spatial and temporal changes in habitat suitability (potential for landscapes to provide habitat for wildlife species based on the species’ requirements); and habitat vulnerability (departure from current or historical conditions) for grizzly bear (Ursus arctos horribilis) Canada lynx (Lynx canadensis).

Results/Conclusions

Our results suggest that spatial and temporal characteristics of wildlife habitat are both climate- and disturbance-driven. Specifically, climate changes dramatically altered vegetation composition, structure, and spatial configuration, especially under natural fire regime conditions, and therefore modified habitat suitability for grizzly bear and Canada lynx. In addition, under climate change conditions habitat recovery following large disturbance events was significantly delayed as compared to historical conditions, and the overall proportion of suitable habitat was reduced across the simulation landscape. Habitat vulnerability varied by species, suggesting that co-distributed species retain species-specific resilience to climate changes and disturbance events based on habitat preferences. Our results demonstrate the value of comprehensive conservation plans that account for these individualistic responses, and highlight the importance of climate and fire in structuring mountainous ecosystems.