Lesson 3: Managing significant karst features

This lesson introduces the management objectives and recommended best management practices for significant karst features.

On this page

• Learning objectives
• Determining the significance of karst features
• Karst reserves and windthrow management
• Significant cave entrances
• Reserves above significant caves
• Significant surface karst features
• Significant karst spring
• Unique or unusual flora/fauna habitat
• Test your knowledge

Learning objectives

In Lesson 2 you learned how significant karst features are usually identified during karst field assessments. Lesson 3 provides more detailed information on significant karst features and how the higher values associated with these types of features can be protected.

By working through this lesson you will:

• Understand the specific management objectives for various significant karst features
• Be familiar with the best management practices recommended for specific significant karst features

Determining the significance of karst features

The significance of karst features, both surface and subsurface, is determined during a karst field assessment.

The criteria for determining the significance of a surface karst feature include:

• Dimensional characteristics
• Level of connectivity between the surface and subsurface
• Hydrological characteristics
• Geological, biological, scientific, archeological, historical, cultural and educational values
• Recreational and commercial values
• Rarity and abundance
• Visual quality

The criteria for determining the significance of caves include:

• Well-developed decorations
• Significant hydrological, archaeological, paleontological or cultural values
• Bat hibernacula or rare cave-dwelling organisms
• Scientifically important climatological or geomorphological sediments
• Significant recreational opportunities
• Unique intrinsic values (for example, large dimensions, unusual configuration, rare/uncommon location)

Since determining the significance of caves requires subsurface inspection and mapping, it should only be done by personnel with specialized knowledge, training and experience.

Karst reserves and windthrow management

The suggested reserve sizes for significant karst features and values in this section are default recommendations. However, local site conditions should be carefully considered when planning reserve shapes and sizes.

The planning and design of all karst reserves should be based on a thorough windthrow assessment. If the default karst reserve recommendations cannot be maintained due to severe windthrow potential, professional judgment should be used to develop site-specific management practices that achieve as many of the management objectives for the reserve as possible.

For more information on assessing windthrow risk:

• Windthrow Handbook for British Columbia Forests.
• Windthrow Assessment Field Cards

Significant cave entrances

The following is a summary of the management objectives designed to protect significant cave entrances. A reserve around a cave site should:

• Maintain the microclimate around significant cave entrances
• Maintain stable habitat conditions for any flora or fauna inhabiting the cave entrance or cave
• Prevent logging debris from entering significant cave entrances
• Provide a measure of aesthetics/recreational experience for cave entrances with high recreational values

Recommended best management practices

1. Leave a minimum two-tree-length reserve extending outward from the mouth of the cave entrance. In the case of a significant entrance contained within a sinkhole, the reserve should extend from the rim or edge of the sinkhole, as defined by the upper break of the slope enclosing the sinkhole. The two-tree-length reserve is based on the average height of the dominant and co-dominant trees at 100 years.
2. Leave an adjacent management zone of an appropriate size to protect the reserve from windthrow. See Managing Windthrow.
3. Leave understorey vegetation along reserve boundaries, and green trees in the opening to help maintain interior microclimatic conditions and inhibit the encroachment of edge species into the reserve

Reserve extends outward from rim of sinkhole

Reserve extends outward from mouth of cave.

For reserves around entrances of caves known to contain bat hibernacula or species at risk, follow the recommendations in Managing Identified Wildlife: Procedures and Measures (PDF).

Cave entrances not meeting significant criteria

Practices recommended for cave entrances that don’t meet the criteria of significant cave entrances include:

• Use a 20-metre management zone around the entrance
• Fall and yard away from the cave entrance as much as possible
• Remove any slash and debris that falls in or around the cave entrance, provided removal does not cause further disturbance
• Retain windfirm non-merchantable trees, advanced regeneration, wildlife trees, and other windfirm vegetation within the management zone

Areas above significant caves

Management objectives are designed to protect the area above significant caves. Reserves in these areas should:

• Maintain stable conditions for karst processes above and within significant caves (for example, temperature, humidity, infiltration rates, drip water chemistry)
• Prevent the migration of surface fines/sediment into significant caves through fissures or cavities in the overlying epikarst
• Protect delicate cave features, cave fauna, etc. from being damaged by vibrations associated with road construction and timber harvesting

Recommended best management practices

1. Establish reserves and management zones of an appropriate size to protect the reserve from windthrow above significant caves situated less than three times the greatest dimension (height or width) of the cave passage below the surface of the ground.

2. Base the size and shape of the reserve on the principle that the cave is primarily affected by diffuse percolation within a 45-degree angle on either side of the outside wall of the cave passage.

3. The size and shape of the reserve can be projected to the surface using cave maps. Significant caves situated less than 10 metres below the surface should receive a reserve in all cases, regardless of whether the cave meets the 3x depth criteria or not. 

4. Significant caves situated less than 10 metres below the surface should receive a reserve in all cases, regardless of whether the cave meets the 3x depth criteria or not.

5. Where the cave ceiling lies more than three times the greatest dimension (height or width) of the cave passage and at least 10 metres below the surface, harvesting can occur safely in most instances.

6. Significant caves that are deeper than three times the greatest dimension (height or width) of the cave passage and at least 10 metres below the surface, but are known to contain exceptional features or values, should receive special consideration.

7. Consider using specialized harvesting practices such as partial cutting, maximum/full suspension yarding, and leaving coarse woody debris and non-merchantable vegetation, to maintain soil humidity above caves with exceptional features or values.

8. The size of the management area for specialized harvesting practices can be projected to the surface using the 45-degree principle.

9. If 0.5 metres or more of soil is likely to be left after harvesting, the use of partial cutting and maximum/full suspension yarding may not be required. However, retaining more coarse woody debris and non-merchantable vegetation should be considered to help maintain soil humidity above the cave.

Significant surface karst features

The following is a summary of the management objectives designed to protect significant surface karst features. These reserve areas  should:

• Protect significant surface karst features from physical damage
• Maintain any site-specific microclimatic conditions and/or habitat/ biodiversity characteristics associated with significant surface karst features
• Prevent soil erosion and sediment transfer into subsurface openings or caves
• Preserve a measure of the aesthetic/recreational experience for surface karst features with high recreational values

Recommended best management practices

1. Leave a minimum one-tree-length reserve extending outward from the edge of the feature. For sinkholes, the edge of the feature should be considered the rim of the sinkhole, as defined by the upper break of the slope enclosing the sinkhole
2. Leave an adjacent management zone of an appropriate size to protect the reserve from windthrow. See karst reserves and windthrow
3. In cases where surface karst features have high recreational values, the reserve size/shape may need to be adjusted to manage visual quality

Sinkholes large enough to create their own microclimate should be managed similarly to a significant cave entrance, with a reserve of two tree lengths to maintain interior microclimatic conditions.

​Significant karst springs

The following is a summary of the management objectives designed to protect significant karst springs. Reserves should maintain:

• Water quality and quantity
• Wildlife habitat
• Visual quality, in cases where recreational values are identified

Recommended best management practices

1. Leave a minimum 20-metre reserve extending outward from the discharge point
2. Leave an adjacent management zone of an appropriate size to protect the reserve from windthrow
3. If the spring discharges into a stream channel or disperses into a wetland, consult the default standards for riparian management as specified in the regulations supporting the Forest and Range Practices Act
4.  Consider the level of activities conducted in the recharge areas of karst springs when managing for water quality and quantity
5. Where unique or unusual species are encountered around karst springs, consult the Conservation Data Centre for assistance in determining appropriate management actions

Karst springs often create favourable environmental conditions and habitats for rare flora and fauna.   

​Unique or unusual flora/fauna habitat

The following section summarizes the management objectives and recommended best management practices for unique or unusual flora/fauna habitats. 

Test your knowledge 

Provide a true or false answer to the self-evaluation questions below.

Go to lesson 4