Impact of fire on montane snowpack energy balance in Snow Gum forest stands

Abstract

Forest stands fundamentally alter hydrology of a region through impacting area micrometeorology and corresponding variability in snow accumulation and melt. Bushfires significantly change these interactions through removal of forest canopy, darkening of tree stems, and post-fire stem decay. This study quantified the impact of pre- and post-bushfire E. pauciflora (Snow Gum) forest stands on snowpack energy balance in the Snowy Mountains of Southeast Australia. Forest canopy cover in undisturbed forest stands moderated snowpack energy exchange through reductions to incoming shortwave radiation and turbulent fluxes. Energy flux to the snowpack was at a maximum in the fire-disturbed forest due to lower snowpack albedo resulting in greater net shortwave radiation and an increased sensible heat emission from decaying tree stems. The fire-disturbed forest also experienced the largest evaporation rate with 8.1% of snowpack SWE being lost to the atmosphere. Dominant energy fluxes to the snowpack were shortwave radiation in the unforested area and fire-disturbed forest stand, and sensible heat in the undisturbed forest stand.