Spruce Beetle Mortality Shows Limited Impact on Forest Fuel Loads
Category: Community Engagement Poster
Author(s): Madi Pinney
Presenter(s): Madi Pinney
Mentors(s): Trevor Carter
Forest disturbances impact ecosystem dynamics, with single events causing economic and ecological consequences, yet their interactions can lead to multiplicative effects. However, we know little about the mechanisms that link widespread disturbances in the subalpine environment. This study examines the connections between spruce beetle-induced tree mortality, soil moisture distribution, and woody debris accumulation in high-elevation spruce-fir forests of the Medicine Bow Mountains, Wyoming. Spruce beetles cause tree mortality in western North American forests, with outbreaks intensifying due to warming temperatures and drought conditions. While previous research has documented changes in forest structure and understory vegetation following beetle outbreaks, the hypothesized mechanisms linking these disturbances to increased fire susceptibility, specifically the relationship between post-outbreak microclimate conditions such as soil moisture and fuel accumulation patterns, remains poorly understood. Using data collected at the Glacier Lakes Ecosystem Experiments Site (GLEES), this research examines how soil moisture and fuels vary across a gradient of beetle-caused mortality. Presently, we build upon earlier work that established significant understory vegetation changes following spruce beetle outbreaks, focusing on how these structural alterations influence fine fuel characteristics that may increase fire ignition potential and spread. We observed no statistically significant relationships between soil moisture, fuels, and overstory mortality. Our findings suggest that the dynamics of fuel accumulation following beetle outbreaks may be more complex than previously assumed, potentially influenced by other environmental factors beyond tree mortality. This work challenges assumptions about post-disturbance fuel accumulation and may help refine fire risk models in western forests affected by spruce beetle outbreaks.