Log and Lumber Grades and Value from a Douglas-Fir Stand 20 Years after Thinning and Biosolids Fertilization

Abstract

Abstract Three replications of four treatments: biosolids fertilization, thinning, thinning plus biosolids fertilization, and untreated control were established in 1977 in a dense, low site, 55-yr-old Douglas-fir (Pseudotsuga menziesii) stand in western Washington. In 1998, 12 trees from each treatment were harvested, bucked into logs, and sawn into visually graded lumber. Taking into account effects of treatments on stand yield and log grades, biosolid fertilization only, thinning only, and thinning combined with biosolids increased log value/ac by $1,142 (19%), $3,642 (62%), and $9,069 (155%), respectively, over the untreated control. When treatment effects were viewed in terms of changes in lumber yield and quality, per acre gains over the control were $2,107 (26%), $5,683 (70%), and $10,708 (132%), respectively. Willingness to pay analysis indicates that if the landowner intends to manage the stand to a rotation of about 75 yr, each of the treatments, and especially the combination of thinning and applying biosolids, appears to be financially attractive at both 5 and 9% interest rates. However, if the rotation had been set at 55 yr, only the thinning/biosolids combination at 5% interest rate would entice management to delay immediate harvest. West. J. Appl. For. 19(1):34–41.