Learning Objectives

Introduction

Best Management Practices

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Karst Management Handbook for
British Columbia

Best Management Practices

The following section summarizes the recommended best management practices for timber harvesting on karst terrain. As these are only brief summaries, you should also check out more detailed information in the Karst Management Handbook for British Columbia.

Low Vulnerability Areas

The following best management practices are recommended:

• Conduct safety briefings for appropriate personnel.
• Flag karst features and/or values within the operating area.
• If previously unidentified karst features or values are encountered, modify or cease operations until the features or values can be assessed. Notify the local Forest Service district office.
• Minimize exposing mineral soil as much as possible.
• Locate storage areas for fuel and other hazardous materials off karst terrain or at least on low vulnerability karst areas (except for daily fuel requirements).

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Moderate Vulnerability Areas

In addition to the recommendations for low vulnerability areas, the following best management practices are recommended on moderate vulnerability areas:

• Consider restricting harvesting to periods when the likelihood of heavy rains and high runoff are low.
• Consider developing site-specific procedures for closely spaced, dense occurrences of minor surface karst features (e.g., falling and yarding away from features, retaining non-merchantable vegetation, removing logging debris from features, etc.). In some cases it may be practical to treat a cluster of minor features as a single unit.

  Figure 7-1: Treating a cluster of minor surface karst features as a single unit.

• Avoid disturbing sideslopes and soil as much as possible when harvesting around sinkholes that do not require a reserve (e.g., fall and yard away, retain non-merchantable vegetation, maximum suspension yarding). Harvesting sinkholes with >70% sideslopes should be carried out very carefully due to the high potential for soil erosion.
• Where falling away from a sinkhole cannot be reasonably achieved, and remaining trees threaten sideslope stability due to windthrow potential, consider falling across the sinkhole if the tree stem will span the feature and can be lifted without damaging the sideslope. If removal will damage residual trees or sideslopes, leave the section of stem spanning the feature, provided it is stable.
• Consider the following when trying to recover logging slash and debris from sinkholes:
  • Clean out debris only if it will not cause further disturbance.
  • Avoid using heavy machinery if damage to sideslopes might occur.
  • Follow machine cleaning with hand cleaning if necessary.
  • Leave naturally fallen trees.
  • Do not remove stable natural material embedded in sinkhole sideslopes or root systems that contribute to sideslope stability.

• Keep the wheels or tracks of equipment at least 5 metres from the edge of karst features. If not possible, keep wheels or tracks parallel to the edge of features.
• Take appropriate measures to correct inadvertent water diversions to prevent sediment transfer into subsurface environments.
• Use protective mats to minimize soil disturbance when hoe chucking.
• Keep skid trails and backspar trails to a minimum and located away from surface karst features and cave entrances.
• Minimize the potential for soil disturbance through maximum suspension yarding.
• Avoid fueling or servicing machinery near surface karst features and cave entrances. Take appropriate measures if spills occur.

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High Vulnerability Areas

In addition to the recommendations for low and moderate vulnerability areas, the following best management practices are recommended on high vulnerability areas:

• Minimize soil disturbance and maintain site productivity on well-developed epikarst with shallow soils by considering the use of:
  • Partial-cutting systems
  • Maximum or total suspension
  • Rubber mats when hoe chucking
  • Helicopter logging.
• When harvesting over caves known or suspected to have thin ceilings:
  • Project the outline of the cave to the surface.
  • Avoid the use of heavy machinery.
  • Assess the size and weight of the timber being felled.
  • Fall and yard away from the underlying cave.
  • Avoid decking logs over top of the cave.
• Avoid piling slash on exposed, well-developed epikarst; use road prisms where possible.
• Attempt to remove fallen trees in or near significant surface karst features or significant caves if it won’t cause further disturbance. (Use full suspension logging if possible.)

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