Bark beetle and fire interactions in Sierra Nevada-mixed conifer forests

The disturbance ecology of coniferous forests of western North America has drastically deviated from historical conditions largely as the result of fire suppression, extreme drought events, and more frequent bark beetle outbreaks. Additionally, treatments to reduce fuel loads will likely be implemented more frequently in order to mitigate increasing wildfire risk. We consider research advancements on the interactions of fire and bark beetles and propose future research to address knowledge gaps. Recent research has advanced our understanding of bark beetle impact on tree mortality probability after low-severity and prescribed fires; however, these findings are not applicable to all forest types. The impacts of bark beetle outbreaks on fuel compositions has also been further elucidated. Long-term studies are needed to better understand the accumulation of surface fuels and downed woody debris following a beetle outbreak.
 
To address these knowledge gaps, we propose investigating the following research objectives over the next four years. First, we propose testing the ability of various model factors, mainly red turpentine beetle (Dendroctonus valens) attack, to predict the probability of ponderosa pine mortality post fire. Under the same project we also plan to assess the interactions of burn seasonality (i.e. fall versus winter versus spring burns) and bark beetle-induced tree mortality at the Blodgett Experimental Forest, El Dorado Co., California. We hypothesize that tree mortality levels will be greater after spring burns. Secondly, we will improve upon current modeling methods used to predict fuel levels in bark beetle-attacked, mixed-conifer forests by analyzing a multi-year dataset.