Influence of Overstory Removal and Western Spruce Budworm Defoliation on Growth of Advance Conifer Regeneration in Montana

摘要

The report studies twelve-year postharvest diameter growth of advance Douglas-fir, Engelmann spruce, and subalpine fir regeneration and 11-year height growth of Douglas-fir and subalpine fir accelerated in response to decreasing competition. Competition was reflected in degree of overstory removal and change in plot basal area. The most influential variable affecting postharvest height and diameter growth was 10-year radial growth prior to overstory removal; trees growing well before harvest grew well after harvest. Postharvest mortality was greatest where about 50% of the overstory was removed. Defoliation by western spruce budworm reduced growth of Douglas-fir but did not affect subalpine fir or Engelmann spruce.