Modeling fire severity and wildfire-driven changes in land cover

Wildfires are the primary disturbance in the Alaskan boreal forest. Burned area and fire severity are increasing in response to increased temperatures in the region. Fires consume aboveground biomass and surface organic materials, which affects post-fire succession. Black spruce stands, which constitute 70 percent of the forest cover in the Alaskan boreal forest, may become dominated by deciduous vegetation if most of the surface organic material is consumed by fire. Assessing fire severity in boreal forests using spectral methods alone cannot determine post-fire organic layer depth, which regulates the success of recruitment and establishment during recovery from wildfire disturbance. However before combining spectral data with ancillary information on topographic position, fire seasonality, weather conditions, and spatial patterns of burned area, it was possible to more accurately estimate burn severity and deciduous transitions for all areas of black spruce that burned in 2004. From this analysis it was estimated that 39 percent of black spruce stands that burned during the five largest fire years of the last decade were vulnerable to a complete or partial shift towards deciduous dominance, and permafrost degradation.