| Abstract/Description or Keywords |
Forest disturbance has a significant impact on forest hydrology due to its effect on the forest canopy, which is important for precipitation interception, evapotranspiration, local meteorology, and snow accumulation and melt. This study examines the impact of mountain pine beetle infestation on forest canopy structure on the Nechako Plateau, and the resulting impacts on snow accumulation and ablation under varied climatic conditions. In high snow years, dead stands behave similarly to alive and clearcut stands due to the ability of large snowfalls to exceed the interception capacity of the canopy. In low to average snow years, however, distinct differences in snow accumulation in dead stands can be attributed to needle loss and canopy reduction due mainly to the loss of small branches and stems. Changing canopy conditions subsequently have a significant impact on local meteorological conditions. Snow ablation is thus driven largely by incoming shortwave radiation, which in dead stands is greater than in alive stands, but is not as great as in clearcuts. Additionally, longwave radiation emission in dead stands is much lower than in alive stands, substantially reducing its contribution to snowpack warming and ablation. Turbulent flux contributions to snow ablation are limited in forest stands, although they are increased slightly in dead stands over alive stands due to the more open structure. Stand-scale results were used to drive a physically-based, distributed hydrological model of the Van Tine Creek watershed and assess watershed-scale hydrologic response to four harvesting/infestation scenarios. snow accumulation; snow ablation; energy balance; runoff; forest canopy; interception; hydrologic modelling |
