They found that even if the climate stopped warming now, high-elevation species such as whitebark pine, Engelmann spruce and subalpine fir will be largely replaced by more climate- and fire-resilient species like ponderosa pine and Douglas fir by the end of the century.
A growing population of shade-loving grand fir that has been expanding in the understory of the forest was also projected to increase, even under hotter and drier future climate conditions, which provided fuels that helped spread wildfires and made fires even more severe.
Brooke Cassell, the study's lead author and a recent PhD graduate from PSU's Earth, Environment and Society programme, said that if these forests become increasingly dominated by only a few conifer species, the landscape may become less resilient to disturbances, such as wildfire, insects and diseases, and would provide less variety of habitat for plants and animals.
Cassell said that the team's findings suggest that forest managers should consider projected climate changes and increasing wildfire size, frequency and severity on future forest composition when planning long-term forest management strategies.
The team also suggests that in light of the projected expansion of grand fir, managers should continue to reduce fuel continuity through accelerated rates of thinning and prescribed burning to help reduce the extent and severity of future fires.