Soil Conservation Surveys Guidebook


Table of contents


3 Definitions and requirements

3.1 Access structures

Access structures located within a cutblock are identified as either permanent or temporary in a silviculture prescription.

Permanent access structures include main haul roads, spur roads, landings, gravel pits, borrow pits, quarries, and permanent logging trails that are built within the total area under the prescription. To be classified as permanent in a prescription, they must satisfy one of the following conditions: a) they must be in use for a long enough period such that, even if they were to be rehabilitated, a commercial crop of trees could not be established on the area occupied by these structures by the time a commercial crop is established on an adjacent area of the cutblock; or b) they must be constructed through soil or rock or ballasted with material that would make them unsuitable for rehabilitation. Such structures are not part of the net area to be reforested (NAR) and do not count towards soil disturbance.

Temporary access structures include roads, landings, pits or quarries, excavated or bladed trails, main skid trails, backspar trails, corduroyed trails, and similar structures within the NAR that are identified as being temporary in a silviculture prescription. Such structures count towards soil disturbance unless they have been rehabilitated. (See "Soil disturbance requiring rehabilitation," below.)

3.2 Soil disturbance

Soil disturbance is a general term referring to the following types of disturbance that occur on the NAR:

Dispersed disturbance is itself a general term referring to dispersed trails, gouges, and scalps. Dispersed trails include wheel and track ruts (normally created during the operation of ground-based equipment on wet soils of limited load-bearing strength) and compaction from repeated machine traffic. Gouges are subdivided into deep gouges, wide gouges, and long gouges. Scalps are divided into wide scalps and very wide scalps.

Some types of disturbance, such as wide scalps and repeated machine traffic, count as soil disturbance only on more sensitive sites.

When soil disturbance is being assessed, it is necessary first to determine which types of soil disturbance will count on the standards unit and which measurement criteria will be appropriate for each disturbance type.

3.3 Soil disturbance requiring rehabilitation

Temporary access structures (including excavated or bladed trails of a temporary nature), compacted areas, and corduroyed trails require rehabilitation, unless exempted by the district manager. If they are not rehabilitated in accordance with the requirements of the regulations, they count as soil disturbance. (Once satisfactorily rehabilitated, they no longer count as soil disturbance.) Survey symbols for bladed trails and similar structures are shown in Table 1.

Soil conservation surveys can be done before these structures are rehabilitated, with the objective of determining the percentage of the NAR occupied by temporary access. Normally, however, soil conservation surveys are conducted after rehabilitation is complete.

Table 1. Soil disturbance categories requiring rehabilitationa


Symbolb

Category

Example


R

Excavated/bladed trails Contour-built skid roads that have not been rehabilitated

Y

Corduroyed trails Skid trails or backspar trails that have been ballasted with logs

A

Compacted areas Junctions of skid trails and excessively compacted roadside work areas

a These categories require rehabilitation unless exempted by the district manager.
b These one-letter symbols are used to record a category of disturbance when conducting a survey.

3.3.1 Excavated or bladed trails (R)

Excavated or bladed trails are constructed trails that have:

The classification of soil disturbance on excavated and bladed trails depends on whether fill slopes are considered a favourable or unfavourable medium for growing trees. (If this is not stated in the silviculture prescription, the section on fill slope soil material in the Soil Conservation Guidebook should be consulted.)

If excavated or bladed trails have been satisfactorily rehabilitated, the exposed mineral soil surface associated with the trail does not count as soil disturbance. The exception is if the trail is under a woodlot site plan (as discussed in the section "Woodlot licence area requirements.")

Unrehabilitated excavated or bladed trails that are not identified as permanent logging trails in a silviculture prescription must be counted as soil disturbance on all sites.

3.3.2 Corduroyed trails (Y)

Corduroyed trails are constructed using logs and woody debris placed side by side to form a surface greater than 2 m in length and capable of supporting equipment traffic. Tree tops and limbs placed in front of harvesting equipment to distribute machine load and reduce soil compaction should not be considered as corduroyed trails, unless the debris prevents the establishment of regeneration at close to the approved target stocking standards. If satisfactorily rehabilitated, a corduroyed trail does not count as soil disturbance.

Unrehabilitated corduroyed trails must be counted as soil disturbance on all sites.

3.3.3 Compacted areas (A)

Compacted areas are areas on which there is evidence of compaction at the survey point and on 100% of a portion that is both greater than 100 m2 in area and greater than 5 m wide.

Assessing compaction

Any of these conditions is considered to be compacted soil: compacted mineral soil, puddled mineral soil, and compacted deposits of slash and organic debris.

Mineral soil compaction is assessed relative to the conditions of adjacent undisturbed soil. Any one of the following defines a compacted condition:

Unrehabilitated compacted areas are counted as soil disturbance on all sites except those with low compaction hazard. Where the compaction hazard has not been assessed, compacted areas are always counted as soil disturbance.

3.4 Dispersed disturbance

The dispersed disturbance categories and symbols are shown in Table 2.

Note that while all the descriptions provided in this section are contained in the Operational Planning Regulation, the regulation does not identify the specific categories by the reference names used here (e.g., the term "repeated machine traffic" is not specified in the regulation, but the description of this category does fall under the definition of a dispersed trail).

Table 2. Dispersed disturbance categories


Symbola

Category

Example


T

Wheel or track ruts Machine traffic on wet soils

E

Repeated machine traffic Skid trails

G

Deep gouges Mound excavations

L

Long gouges Excessive ripper-plow trenches, poor mounding

W

Wide gouges Poor screefing, mounding, or stumping; intermittent trail
blading

V

Very wide scalps Scalping during piling, scalping on skid trails, areas where the forest floor has been completely burned off

S

Wide scalps Aggressive patch scarification scalping during piling, or on skid trails

-

Not counted
(undisturbed, etc.)
Survey points not meeting the criteria of categories above, or that fall on large logs, boulders, or slash piles where the ground surface cannot be seen and reliable assessment cannot be made

X

Not surveyed Points that fall outside the NAR (e.g., on a permanent landing)

a These one-letter symbols should be used in field surveys to record soil disturbance.

3.4.1 Dispersed trail: wheel or track ruts (T)

Wheel or track ruts are impressions or ruts in the soil caused by heavy equipment traffic. They are at least 30 cm wide and 2 m long. Two different depth criteria (5 cm and 15 cm) apply, depending on the compaction hazard of the standards unit being assessed. On sites with a high or very high compaction hazard, or where the compaction hazard has not been assessed, both depth criteria apply. On sites with a moderate or low compaction hazard, only the 15 cm depth criterion applies. This category does not require the survey point to be assessed for evidence of compaction.

Ruts 15 cm deep

Ruts must have a minimum depth of 15 cm at the deepest point in the perpendicular cross-section, over the entire length of 2 m. Depth is measured from the surface of the undisturbed forest floor to either the forest floor surface in the bottom of the rut or the mineral soil surface in the bottom of the rut if a forest floor is not present.

Wheel or track ruts 15 cm deep are counted as soil disturbance on all sites.

Ruts 5 cm deep

On sites with high or very high compaction hazard, both 15-cm-deep ruts and ruts at least 5 cm deep into mineral soil should be counted. Depth is measured from the surface of the undisturbed mineral soil to the mineral soil surface in the bottom of the rut, ignoring any forest floor that may be in the rut.

Measure at the deepest point in the perpendicular cross-section over the entire length of 2 m (Figure 1).

Wheel or track ruts 5 cm deep are counted as soil disturbance on sites with high or very high soil compaction hazard or where compaction hazard has not been assessed.

Figure 1. Depth assessment of wheel or track ruts.

Top view: The depth assessment for wheel or track ruts uses the deepest point in the perpendicular cross-section of the rut, not the depth exactly at the survey point, as is the case for most other disturbances.
Side view: (1) On all sites, ruts can be assessed using the depth of 15 cm from the surface of the undisturbed forest floor to the top of the forest floor in the rut.
(2) Where forest floor is not present in the rut, measure at least 15 cm from the top of the undisturbed forest floor to the mineral soil surface in the rut.
(3) For sites with very high or high soil compaction hazard or where the compaction hazard has not been assessed, measure at least 5 cm from the surface of the undisturbed mineral soil to the mineral soil surface in the bottom of the rut. The mineral soil itself must be depressed 5 cm.
(4) When assessing 5-cm-deep ruts into mineral soil, gently brush aside any forest floor if it is present in the bottom of the rut, and measure to the mineral soil surface in the bottom of the rut.

3.4.2 Dispersed trail: repeated machine traffic (E)

The category repeated machine traffic describes disturbance resulting from repeated heavy machine traffic. Such disturbance is typically found on repeatedly used skid trails, which are obvious linear features. It may also occur on heavy traffic areas associated with roadside work areas and around piles constructed by windrowing or piling slash. This disturbance rarely occurs on moderate compaction hazard soils logged under dry conditions, where random skidding operations have limited the use of trails to one or two passes.

The following criteria define repeated machine traffic:

- altered soil structure or increased density relative to the surrounding soil,
- puddling, and
- compacted deposits of forest floor, fine slash, and woody debris overlaying and partially imbedded in, or crushed into, the mineral soil (compacted such that they cannot be readily excavated with a shovel).

Repeated machine traffic must be counted as soil disturbance on all sites except those with low compaction hazard. Where the compaction hazard has not been assessed, repeated machine traffic must be counted as soil disturbance.

3.4.3 Deep gouges (G)

Deep gouges are excavations into mineral soil that are deeper than 30 cm or to bedrock at the survey point.

Measure from the undisturbed mineral soil surface to the mineral soil surface in the gouge.

Deep gouges must be counted as soil disturbance on all sites.

3.4.4 Wide gouges (W)

Wide gouges are excavations into mineral soil that are a) deeper than 5 cm at the survey point and b) deeper than 5 cm or to bedrock, on at least 80% of an area 1.8 x 1.8 m.

Measure the depth of the gouge from the undisturbed mineral soil surface to the mineral soil surface in the gouge.

Wide gouges must be counted as soil disturbance on all sites.

3.4.5 Long gouges (L)

Long gouges are excavations into mineral soil that are a) deeper than 5 cm at the survey point and b) deeper than 5 cm or to bedrock on 100% of an area 1 x 3 m.

Measure the depth of the gouge from the undisturbed mineral soil surface to the mineral soil surface in the gouge.

Long gouges must be counted as soil disturbance on all sites.

3.4.6 Very wide scalps (V)

Very wide scalps are areas where the forest floor has been removed at the survey point and from over 80% of an area 3 x 3 m.

Forest floor is considered removed when the underlying mineral soil is exposed as a result of scalping, gouging, or burning, and the exposed mineral soil is covered by:

Forest floor is not considered to be removed when it is:

Very wide scalps must be counted as soil disturbance on all sites.

3.4.7 Wide scalps (S)

Wide scalps are areas where the forest floor has been removed at the survey point and from over 80% of an area 1.8 x 1.8 m.

The same definition of forest floor removal applies here as is described above for very wide scalps.

Wide scalps must be counted as soil disturbance on sites with:

3.4.8 Rehabilitation disturbance

Rehabilitation disturbance occurs when a temporary access structure or other type of soil disturbance is satisfactorily rehabilitated.

Record points that land on rehabilitation disturbance as not counted or undisturbed ("-").

The acceptability of rehabilitation should not be assessed using the soil conservation surveys described in this manual, but should be evaluated based on completion of the treatments as required in the Timber Harvesting Practices Regulation or described in a soil rehabilitation plan. (Note that rehabilitation disturbance can be dealt with differently under woodlot licence areas, as described in the section on "Woodlot licence area requirements.")

3.4.9 Prescribed fire impacts

Large areas where prescribed fire has completely consumed the forest floor should be treated like scalps. Prescribed fire impacts must be counted as soil

3.4.10 Woodlot licence area

Requirements and definitions related to soil conservation on areas under woodlot licences are provided in the Woodlot Licence Forest Management Regulation, which came into effect on November 30, 1998. Before this date, the requirements for woodlot licensees were the same as for major tenure holders. The following discusses some of the requirements of the new regulation.

The district manager can direct the woodlot licensee to conduct a survey to determine both the total area of the cutblock occupied by permanent access structures and the nature and extent of soil disturbance in the NAR.

For woodlot licence areas, a permanent access structure is any in-block road, landing, pit, or quarry not identified as requiring rehabilitation in an operational plan. Excavated or bladed trails, other logging trails, or similar structures may also be permanent access structures if identified as such in an operational plan. The maximum proportion of the total area within a cutblock that may be occupied by permanent access structures is the amount specified in an operational plan, or 7% if there is no amount specified.

Those structures not identified as permanent access structures and not rehabilitated contribute to the total area occupied by soil disturbance. The maximum proportion of any standards unit within the NAR that may be occupied by soil disturbance is the amount specified in the forest development plan or site plan, if an assessment of soil hazards has been carried out. If an operational plan for the area does not specify the maximum proportion of the NAR that may be occupied by soil disturbance, then the limit is 5%.

For areas covered by site plans, the maximum limit for soil disturbance must accommodate the area that will be occupied by all non-permanent access structures. (Note that the term "temporary access structure" is not used, nor defined in the Woodlot Licence Forest Management Regulation.) Even after these structures are rehabilitated, they may still be counted as soil disturbance if they meet any of the criteria for dispersed disturbance. For example, the surface of a rehabilitated temporary road that does not have any forest floor remaining could be categorized as a scalp and therefore count as soil disturbance. (This would not count on an area covered by a prescription held by a major licensee or a timber sale licensee.)

For areas covered by silviculture prescriptions approved before the Woodlot Licence Forest Management Regulation came into effect, access structures identified as requiring rehabilitation do not count as soil disturbance if they are satisfactorily rehabilitated.

For an area under a stand management prescription that calls for mechanized ground-based stand tending treatments using heavy machinery, the maximum proportion of the area to be treated that may be occupied by soil disturbance is the amount specified in the prescription-or 5% if no amount is specified.


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