Abstract:
Many high-elevation stands of noble fir in the northern Oregon Cascades are being
actively managed. Forest managers are investigating different activities that will control
stand impacts and the subsequent spread of Heterobasidion annosum a rot pathogen on
the Warm Springs Indian Reservation. The purpose of this study was to quantify the
relationship of logging production and costs with associated residual stand damage during
a commercial thinning operation. Investigated in the study were four ground-based
harvesting systems and two different harvest unit layout methods.
The harvest systems encompassed a variety of equipment and mechanization levels
ranging from mechanized felling and bunching with grapple skidders to manual felling,
limbing, and bucking using a rubber-tired skidder equipped with a winch line. In addition,
each harvest system was compared using two layout methods. The first method was
conventional or logger's choice and the second was a designated method incorporating
proven methods for reducing stand damage. Log lengths varied from whole-tree to log-length
depending on the harvest system employed. Logging production and costs were
determined for the harvesting systems using a combination of detailed and shift level time
studies. A stand damage survey conducted simultaneously with production studies
determined percent residual stand damage, specific equipment causing damage, and
individual scar characteristics.
Harvesting costs for the four different systems and layout methods ranged from
$67.77/MBF-$92.68/MBF, with residual stand damage of 20.12-62.62%. Equipment
size, log lengths, and layout method were found to affect total residual stand
damage. Reducing the use of larger, more mechanized pieces of equipment in the stand
and keeping log length to a minimum resulted in a significant decrease in residual stand
damage. Cost differences between designated and conventional layout methods for each
harvest system were minimal. The main difference in harvesting cost was between the
different systems and log lengths. Harvesting costs varied, being similar for the highest
and lowest mechanized systems but increasing with the intermediate harvesting systems.
