IntensIve sIlvIculture - Forest Science Labs - Research Network ...

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Application of these observations for salal control (to reduce competition), or to increase salal
browse production, are discussed.
557. Smith, S.H. and J.F. Bell. 1983. Using competitive stress index to estimate diameter growth for
thinned Douglas-fir stands. Forest-Science 29(3): 491-499.
Keywords: thinning
growth
Abstract: A set of linear growth equations was developed using initial diam. (d.b.h.), initial
competitive stress index (CSI, based on area of overlap of growing space), and change in CSI due
to thinning as independent variables to predict periodic diam. growth response for 3- and 4-yr
growth periods. CSI values were calculated from data collected in a naturally developed, pure,
even-aged stand in Oregon [see FA 34, 2219]. Study plots were established in 1963, when the
stand was 20 yr old, and thinned at varying intensities in 1963, 1966, 1970 and 1973. The data
was divided into 2 periods: 1966-70 and 1970-73. Functions including all 3 independent variables
accounted for the greatest variation in periodic diam. increment for both growth periods.
Including transformations of initial CSI and change in CSI in the model provided significant
improvements over a model based only on functions of initial d.b.h.
558. Sonne, E., E. Turnblom, D. Briggs and G. Becker. 2004. Log and lumber grades and value from a
Douglas-fir stand 20 years after thinning and biosolids fertilization. Western-Journal-of-Applied-
Forestry 19(1): 34-41.
Keywords: fertilization
thinning
economics
yield
wood quality
Abstract: Three replications of four treatments: biosolids fertilizer application, thinning,
thinning plus biosolids fertilizer application, and untreated control were established in 1977 in a
dense, low site, 55-year-old Douglas-fir (Pseudotsuga menziesii) stand in western Washington,
USA. 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 fertilizer application only, thinning only, and thinning combined with biosolids increased
log value/ac by $1142 (19%), $3642 (62%), and $9969 (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 $2107 (26%), $5683 (70%), and $10 708 (132%), respectively.
Willingness to pay analysis indicates that if the landowner intends to manage the stand to a
rotation of approximately 75 years, 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 years, only the thinning/biosolids combination at
5% interest rate would entice management to delay immediate harvest.
559. Sorensen, F.C. 1996. Effects of length of seed chilling period and sowing date on family
performance and genetic variances of Douglas-fir seedlings in the nursery. New-Forests 12(3):
187-202.
Keywords: nursery operations
tree phenology