Production rates and costs for skyline harvesting were examined over a range of residual thinning intensities, operational methods, and sites. The sites included three stands of 40- to 50-yr-old Douglas-fir on the Willamette National Forest in the Cascade Mountains of Oregon. Three silvicultural treatments were studied at two sites, and one silvicultural treatment at the third site. Detailed time studies were conducted on manual felling and uphill skyline yarding with small or mid-size yarders. Separate regression equations were developed to predict delay-free felling cycle time and delay-free yarding cycle time at each site. The three silvicultural treatments had no consistent influence on production rates and costs, because the initial stocking levels varied among treatments and the volume harvested did not necessarily correspond to the silvicultural treatment. Cost differences within sites, where operational methods were uniform, were small. Cost differences among sites for each activity, such as felling or yarding, were larger because of differences in operational methods. Total harvesting costs among the three sites were similar, ranging from $58 to $64/100 ft³.
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