Western Dwarf Mistletoe and Prescribed Fire Behavior—A Case Study from Crater Lake National Park

Abstract

This study investigates the influence of parasitic western dwarf mistletoe on prescribed fire behavior and limb flammability of ponderosa pine. Fall season prescribed fires were applied to 14 plots (7 infested and 7 uninfested) in an 81.5 ha mixed-conifer stand at Crater Lake National Park. I measured stand structure variables and surface fuel composition before and after burning and monitored fire behavior during burns. To assess the influence of mistletoe infection on limb flammability in a more controlled setting, I burned infected and uninfected limbs (n = 18 each) in a burn chamber. Results show that plots at Crater Lake infested with mistletoe burned at higher temperatures for shorter periods than uninfested plots. Plots with greater duff biomass recorded higher temperatures, while those with greater accumulations of litter burned longer. All plots experienced a significant reduction in total surface fuel loads following fire, however there was no difference in fuel reduction between uninfested and infested plots, suggesting mistletoe has little influence on fire behavior in this forest type. Infected branches lost a greater proportion of their mass during burn chamber tests, primarily in the form of needles. These results indicate that dwarf mistletoe has little influence on the behavior of low-intensity surface fires, but further research is needed to assess the role of mistletoe in other fire conditions and stand types.