Putting more fuel on the fire… or maybe not? A synthesis of spruce beetle and fire interactions in North American subalpine forests

Large scale native spruce beetle outbreaks and fires are major disturbances in high elevation forests throughout western North America. These disturbances have independently impacted hundreds of thousands of hectares of forests in the last decade in Colorado alone. There is a concern that these two disturbances will interact with each other in the future to create novel forest conditions. Both fire and spruce beetle outbreaks have been investigated thoroughly as individual disturbances; however, to our knowledge, our review is the first to synthesize prior research on spruce beetle and fire interactions to understand the importance of a first disturbance for altering the conditions needed for a future second disturbance. The current and widespread view that spruce beetle outbreaks add fuel to the landscape that increase future fires is likely not appropriate in this system. Instead, future research will need to investigate how a first disturbance can alter the microclimate and other environmental properties needed for a second disturbance.