EFFECTS OF PARTIAL BARK REMOVAL ON THE GROWTH OF PACIFIC YEW

Whole-tree harvest of Pacific yew (Taxus brevifolia Nutt.) to provide bark for production of the new anticancer drug taxol may adversely aff ect stand structure where yews provide thermal cover, browse, or ripar ian benefits. Harvesting only a portion of the bark on standing trees would maintain existing stand structure if the affected trees continue d to grow, but partial bark removal seldom has been applied because it s long-term effects are unknown. We measured 121 yews that had been sc arred by windthrow or logging damage 3-92 years ago and found that the ir growth did not differ significantly from the growth of nearby unsca rred yews. Radial growth of the scarred trees was strongly correlated with growth before scarring; it was slightly associated with overstory canopy density, elevation, and the amount of bark removed. Partial ba rk removal from one side of the tree probably will not seriously affec t the growth of Pacific yew if less than 50% of the bark is removed.