Born to Burn: Characterization of Fuel Loads, Flammability and Plant Traits Across Spatiotemporal Gradients of Black Spruce Dominated Communities

Abstract:

For the last 7000 years, black spruce dominated plant communities in interior Alaska have been adapted to a low to moderate severity fire regime. Recent intensification of interior Alaska’s fire regime is leading to shifts in post-fire stand recovery from black spruce-dominated to deciduous-dominated stands. Current research on black spruce forest fuel loads in interior Alaska focuses largely on organic soil and tree canopy fuel loads; few studies have investigated understory fuel loads and many studies lack replication across entire spatiotemporal scales. Additionally, little is known about the phenotypic plasticity of fire-ecological plant traits across the black spruce forest landscape and whether fire-ecological plant traits can be used to indicate a site’s resiliency to changes in the fire regime. With the aim of increasing our understanding of the variation in black spruce forest flammability, we quantified fuel load in organic soils, understory plants and tree canopy in 28 black spruce dominated sites ranging across age and moisture gradients in interior Alaska. We used the fuel load data, along with boreal plant SLA measurements from the literature (a trait highly related to plant flammability), to calculate a flammability index for each site. Fire-ecological plant traits were measured for Vaccinium uliginosum (blueberry) and Hylacomium splendens (splendid feather moss), two very ubiquitous species present within these sites, in order to investigate relationships between trait plasticity and inherent site characteristics. The results of this study will be applied to a framework that can assist fire managers in the prediction of fire potential and its behavior, and to anticipate post-fire ecological effects.