- Over the past 15 years, changes in forest-management values have led to an
increase in the amount of planning requirements necessary to complete harvesting
activities. The measurement of forested land areas is typically a large part of
operational plans. In the two studies presented here, new measurement technologies
were examined for their effectiveness in meeting those requirements. Both
investigations involved area measurements and corridor layout in the Oregon Coastal
The first study compared four survey techniques for traversing 16 1-ac patches:
1) string box, hand-held compass, and clinometer; 2) laser, digital compass, and digital
data collector; 3) global positioning system (GPS); and 4) the benchmark method, as
set with a total station. Defining the effectiveness of each system was based on predetermined
management objectives, including the precision and accuracy of data, time
to complete the survey, and cost. Precision was highest with the total station, while the
laser and digital compass method required the most time. The least expensive
technique was the string-box method. GPS proved ineffective under dense canopy
conditions. Potential differences in the orientation of harvest units were revealed
because of variations in the horizontal angles used for measurements.
In the second study, two surveying techniques were compared against a
benchmark (i.e., total station) for profiling skyline corridors for commercial thinning.
The first method employed a string box, clinometer, and hand-held compass; the
second, a laser, digital compass, and digital data collector. Analysis of the profile
information (slope distance and slope percent) by LoggerPC4 showed no significant
differences (p<0.57) in lbs-per-payload results between the two surveying methods,
based on t-tests. The string-box technique was most effective in terms of time (10.8 hr
vs. 13.5 hr from the laser/digital method) and cost (S0.35/mbf vs. S1.00/mbfj. These
contrasts might be attributed to differences in: 1) the position of the critical point due
to elevational changes within the mid third of the profile; 2) the elevation of the
intermediate support; and 3) elevation of the tail hold.
The results of both studies demonstrate that many tools are available for
completing operational planning and layout. Each has benefits and drawbacks that
should be matched to the operational plan objectives.