Effects of small logged openings on snow ablation during a high snow year

The effects of small logged openings on snow ablation rate were studied from 1994 through 1998 at a sub-alpine silvicultural systems research site in the Quesnel Highland of B.C. Six snow plots were in north-facing treatment units from which 21 to 34 percent of the forest had been previously harvested and one was installed in an unharvested control. One purpose was to determine the potential effects of group selection on peak streamflows in the event that this silvicultural system is applied over large areas. Average ablation rates in openings increased from 1.6 to 2.2 cm per day as opening diameters increased from 1 to 5 tree heights (1H to 5H). There was no significant effect of small openings on ablation rates in the adjacent trees. The net effect of harvesting 30 percent of the area in the form of 3H and 5H openings was that ablation rates increased by 5 and 13 percent respectively in a year with above-average snowmelt-generated peak streamflows.