EFFECTS OF VARIABLE FIRE SEVERITY ON FORAGE PRODUCTION AND FORAGING BEHAVIOR OF MOOSE IN WINTER

Abstract

The increasing frequency and extent of wildfires in Alaska over the last half century has spurred increased interest in understanding the role of post-fire succession on vegetation establishment. Our primary goal was to examine how wildfire affects production and distribution of winter forage for moose  (Alces alces) in interior Alaska, and how these changes in forage availability control forage offtake. Fire severity classification was based on post-fire depth of residual soil organic matter. We used a browse survey protocol to estimate the biomass of current year production (kg/ha) and overwinter offtake (kg/ha) by moose. Under the assumption of homogenous effects of fire severity on regeneration, we estimated that moose consumed 36% of all forage (current annual growth) across the study area. However, we found that moose exhibited significantly higher browse consumption relative to browse production in high fire severity sites than in low severity sites (P < 0.05). When we adjusted our estimates of forage production and consumption by accounting for the significant differences in browse consumption between severity classes and their distribution across the burn, moose consumed approximately 49% of available forage. Assessments of fire severity and its spatial distribution through remote sensing techniques and on-the-ground sampling provides improved projections of vegetation regeneration pathways following wildfires, and thus refined estimates of future browse production and habitat quality for moose.