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Coarse Woody Debris Pilot Study

    The objective of this project is to determine if in Coastal old-seral stands modified bucking and yarding practices (i.e., bucking to create higher value logs and marking of non-merchantable logs for retention) are effective and economically feasible methods to increase CWD left in the setting post-harvest.

    Current harvesting practices, particularly in decadent stands, can result in large accumulations of non-merchantable wood either at the roadside or dry land sort. This reflects a combination of factors from the felling and bucking practices to the cost reduction incentives under the utilization policy. Other contributing factors may include visibility during yarding such that the merchantability of the log is not apparent until after the log is yarded to roadside, or in other cases fuel abatement and/or plantable spot requirements. However, these latter issues are perhaps less influential than the former. Standard felling practice requires fallers to fell trees at 0.3 m, unless there are safety issues. Stems are typically bucked to company specified log lengths which are generally between 8 to 15m with some variation depending upon final product objectives. The maximum log length allowed is a function of the trucking phase. In hand falling, the fallers are expected to buck the felled tree into multiples of company specified log lengths and de-limb 3 sides of the stem unless it is unsafe to do so. Most often the butt and second cuts are separate logs, with the tops left to go to the sort as one piece. In some instances multiple logs are left joined together to maximize yarding efficiency. As a general rule fallers do not “long butt” if the butt rot is close to 50% sound merchantable. The faller will measure a pulp log and a saw log before bucking to put the final bucking decision in the hands of a certified grader. At the landing the chaser removes the remaining limbs, bucks broken log ends and bucks the occasional over-length logs. Usually the chaser does not have a scaling ticket and will not make merchantability decisions. Most companies would rather yard and truck some non-merchantable material rather than risk the penalty of having to re-yard a setting. The flip side of the coin however is that waste accumulations can result in increased yarding, sorting, and waste disposal costs. Recently, two practices have been used successfully in Weyerhaeuser’s helicopter-logging operations to reduce yarding/hauling costs and dryland sort accumulations :

  • On-site bucking to create higher value logs (CHVL). In this approach low value wood e.g., Z grade, is bucked and left in the setting.
  • Marking to leave grade Z and Y logs on site (marking occurs after falling and bucking, but prior to yarding) (MTL). A cruiser or scaler paints non-merchantable wood after falling but prior to yarding. In cable systems, if visibility is limited, it is necessary for the bull-bucker to identify these logs to the yarding operator.
  • Based on Weyerhaeuser’s results, it is believed that CHVL and MTL practices may provide economic and eco-logical benefits under other harvesting systems and in certain ecosystems. Therefore, this project will investigate the economic and ecological implications of maintaining CWD in the harvest setting through the use of CHVL and MTL. The project will focus on cable-harvesting operations in late-seral forests in the Coast Forest Region in wet to moist CWH subzone variants, i.e., Natural Disturbance Type 1 (NDT1) variants such as vm1, vm2, and mm (BGB 1995). It is anticipated that these forest/ecosystem types have the greatest volume of low-value material (i.e., Y and Z grades) due to advanced stand age and level of decadence. Cable harvesting is the dominant sys-tem in these types of stands.

    The document titled Maintaining Coarse Woody Debris in Post-Harvest Settings: Economic and Ecological Implications of Marking Non-Merchantable Logs After Bucking and Before Yarding is the project plan for the pilot study.

  • Other initiatives include completion of data collection on two studies investigating trends in dead wood (downed and standing) volume, attributes and distribution in mature and old growth stands under clearcut with reserves and alternative silvicultural systems prior to and following harvest. Data analyses and draft report for one study.

  • Return to CWD Home.


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    Comments to: Denis Collins
    This page last updated: June 18, 2001
    URL: https://www.for.gov.bc.ca/rco/research/vanprojects.htm

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