Effects of Mountain Pine Beetles and Timber Harvesting on Stand Attributes and Snow on the B.C. Interior Plateau

Considerable progress has been made in describing the effects of clearcut harvesting and reforestatation on snow accumulation and melt relative to mature healthy forests. However, in the aftermath of the recent mountain pine beetle infestation in B.C., the effects of harvesting beetle-killed pine stands need to be compared with what would have happened if the killed stands had been allowed to develop naturally. This paper reports on a project in which snow accumulation and ablation were compared in recent clearcuts, partially recovered plantations, and in natural pine stands at different stages of disturbance and recovery. SWE and ablation rates in treed plots were standardized by calculating ratios of SWE and ablation rates in treed plots to those in nearby clearcuts. SWE ratios were > 1 in only 3 of the 19 treed plots - a recently-defoliated stand and two plantations under 15 years old. Snow ablation ratios were > 1 only in a 15 year-old plantation. SWE ratios and ablation ratios in plantations and killed pine stands were analyzed as functions of time since disturbance. Results suggest that harvesting recently-killed pine stands could increase the rate of snowmelt for 15 to 25 years on the B.C. Interior Plateau.