Scar closure and future timber value losses from thinning damage in western Oregon
2000
Han, H.S. | Kellogg, L.D. | Filip, G.M. | Brown, T.D.
This study investigated bark growth and decay development after thinning damage at two western Oregon sites, and estimated value loss with a tree growth model. All scars that remained open in western hemlock (Tsuga heterophylla) and Sitka spruce (Picea sitchensis) had advanced decay 13 years after initial wounding. Scars less than 4 inches wide closed in 8 years. Douglas-fir (Pseudotsuga menziesii) was more resistant to decay; no rot was observed in scars less than 21 years old. Advanced decay and pitch rings, however, were observed in 29-year-old scars, both open and closed. Because of these defects, future value loss increased with time after wounding and with higher stand damage levels. Fifty years after thinning, about 2 percent of the total future log value, or $189/ac. (1997$), could be lost in Douglas-fir stands with 20 percent stand damage and a 2-inch diameter deduction. This loss could be reduced to $58/ac. if stand damage were minimized to 5 percent with more careful techniques. The increase in thinning costs ($61/ac. for tractor thinning; $79/ac. for cut-to-length; $124/ac. for skyline; with a 5% increase in production time) that is incurred while trying to minimize stand damage could be justified if it reduced future value losses to crop trees.
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