Description:
Harvesting productivity rates and costs were determined for three
silvicultural treatments used in commercial ground-based thinning of
young stands to achieve timber management objectives and enhance
wildlife habitat. Treatment definitions were based on residual trees
per acre (tpa) after thinning. The treatments were light thin (115
residual tpa), light thin with 0.5-ac openings (92 residual tpa), and
heavy thin (53 residual tpa). The three study sites were 44- to 46-
yr-old stands of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco]
located in the Cascade Mountains of west central Oregon. Detailed
time studies were conducted on timber fallers and crawler tractors
and used to develop multiple linear regression models to predict
delay-free felling and skidding cycle times for each site. The independent
variables common to the regression models to determine
delay-free felling cycle time at all sites were diameter at breast height,
number of cuts, and number of limbs cut. Only skidding distance
was common to all regression models for determining delay-free
skidding cycle time. Total costs for each treatment were obtained
by combining felling, skidding, and moving costs for the entire
operation. Felling costs ranged from $7.20/CCF to $17.73/CCF.
Skidding and loading costs ranged from $15.42/CCF to $38.69/
CCF. The cost and productivity results from this study emphasize
the importance for forest managers to consider factors such as volume
removed and skidding distance when prescribing alternative
silvicultural treatments for young Douglas-fir stands.