Windthrow damage 2 years after partial cutting at the Date Creek silvicultural systems study in the Interior Cedar–Hemlock forests of northwestern British Columbia

Abstract

Partial cutting that removed either 30 or 60% of the volume as single trees or small groups up to 0.5 ha had little effect on wind damage to merchantable trees (≥17.5 cm diameter). On average, 6.7 stems per hectare of windthrow occurred across unlogged and logged units, representing approximately 1.9% of the standing trees. Over 2 years, 0.63 m 2 ·ha n1 of merchantable basal area was damaged, or 1.5% of the original standing basal area. In the partial cuts, 2.2% of the trees were damaged compared with 1.1% in unlogged areas. The 1.1% increase in damage in partial cut units was well below the 10% effect size considered large enough to warrant either management intervention or to deem the partial cutting a failure. The greatest wind damage occurred in the old-growth stands. For 8 of the 9 tree species examined, no individual tree characteristics seemed to predispose them to wind damage. Abies amabilis (Dougl. ex Loud.) Dougl. ex J. Forbes, Populus tremuloides Michx., and Abies lasiocarpa (Hook.) Nutt. were the most susceptible species to windthrow.