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Initial planning for mechanical site preparation is conducted at the Pre-harvest Silviculture Prescription (PHSP) stage. The PHSP will state whether or not site preparation is required to achieve free growing stocking standards and other reforestation objectives. If the choice of mechanical site preparation has been made, the treatment type (e.g., scalping, mounding, or mixing) should be stated in general terms. Consideration should have been given to the costs and benefits of the various treatments (see Appendix 3, Equipment Comparison: Costs and Productivity, for comparative cost figures). If planting will be required, regional stocking standards and the number of acceptable naturals will determine the number and spacing of plantable spots to be prepared. If site preparation is for naturals, the amount and a definition of suitable seedbed should be stated.
Following harvest, the appropriateness of the PHSP can be checked using the FS 117 form. This process fine-tunes the prescription since conditions present after harvest may not match those that were anticipated in the PHSP. Once the prescription has been confirmed and the treatment and equipment selected, the project is ready to be implemented. For additional information, refer to "Project Management" and Appendix 1, Forms Management.
Timing Treatments to Minimize Site Disturbance
The majority of mechanical site preparation is carried out during the summer and fall months, once sites have dried out sufficiently to allow machine traffic. The wetter the soil, the greater the risk of causing compaction and rutting damage. It is important to be aware of the compaction hazard of the site and to monitor soil moisture. At times, treatments such as shearing and piling should be carried out only after the ground is partially frozen. For more information, see Curran et al. .
There are two main types of treatment patterns: back-and-forth and concentric. The concentric pattern is used to minimize the time spent turning, or when turning is difficult, for example, during drag scarification. When working in a concentric pattern, the operator begins along the outer edge of the cutover and continues to go around and around until the whole area is treated.
The back-and-forth pattern is used when other considerations, such as planter access or aspect, take priority over machine productivity. The operator begins at one end of the cutover and drives back and forth in parallel runs, usually perpendicular to the road. The runs should be longer than 150 m to ensure that time spent turning is appropriate relative to the total working time.
The treatment pattern may also have to be modified to accommodate site factors such as slope, bedrock, wet pockets or natural regeneration.
On some sites, integrated resource management may result in areas requiring modified treatment. Two examples are given below:
Yew - The discovery of a cancer treating agent in yew bark has resulted in the protection of yew trees being a high priority. If yew trees are left on a block to be treated following harvesting, ensure that the site preparation contractor is aware of this at the pre-work conference.
Wildlife Trees - The protection of wildlife trees has received considerable attention recently. Such trees, protected through harvesting, should be identified and should not be disturbed by site preparation operations. Such trees may have modified work zones flagged out where machine traffic is not allowed, or where it may not be safe for ground workers. In any case, designated wildlife trees should be pointed out to the site preparation contractor or operator at the pre-work conference. For further information, see Wildlife tree management in British Columbia [Backhouse 1993].
Safe operating techniques and procedures are always important. In site preparation, unlike harvesting operations, the contractor is usually operating in isolation from other equipment or activities. Therefore, it is desirable to operate equipment in pairs whenever possible. Prime movers should always be equipped with a two-way radio or mobile telephone. Fire safety is also a concern, especially during periods of dry weather. Sparks can fly from the prime mover, or implements, and can ignite ground vegetation or logging debris. Welding, cutting, and metal grinding should not be performed in the cutover. During periods of high fire hazard, personnel with firefighting equipment should be posted to watch over the workplace after treatment has ended, and after machine repair work has been completed. Site preparation operations should be equipped with safety and firefighting equipment as specified by the ministry. Complete directions for firefighting must be supplied by the supervisory staff.
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