This section provides recommendations regarding silviculture, harvesting, and road construction practices within the RMA. Range use guidelines are contained in the section "Range in riparian areas."
These recommended forest practices were developed with consideration given to their potential impact on timber supply. Given the high degree of variability in site conditions within riparian management areas, it is not possible to provide a single prescription suitable for universal application. Site-specific decisions must be made regarding the appropriate level of retention within riparian management zones and the types of trees to be retained. Such factors as topography and windthrow hazard will determine the best management practice on a site specific basis. In addition, on each site where a level of tree retention is prescribed, the forest management practice specified for the portion of the management zone not occupied by retained trees must be adequate to ensure that these areas are fully productivity. This is required to ensure there are no unaccounted timber supply impacts attributable to the implementation of these riparian management recommendations.
The following table summarizes the maximum overall levels of retention within the riparian management zones for each riparian class of stream, wetland and lake that are anticipated to result from consistent implementation of the best management practices recommended in this guidebook. The maximum overall levels of retention represent the average levels of retention for all of the reparian management zones for each reparian class of stream, wetland and lake that occur within the cutblocks identified in a forest development plan.
Table 4. Maximum overall average levels of basal area retention within the riparian management zone for each riparian class of stream, wetland, and lake.
These overall retention levels are not intended to be applied on a cutblock by cutblock basis and should not be interpreted as being the required or target level of retention for every riparian management zone. Site-specific application of the range of best management practices should ensure that the overall retention within a forest development plan area does not exceed the maximum levels specified. In some circumstances, e.g. forest development plan areas dominated by high windthrow hazards, the overall level of retention may be lower than that specified in the table.
The following section applies to all riparian areas plus FSZ and MSZ and are to be viewed as 'Best Management Practices' to guide development of prescriptions for the RMA of each riparian class.
Riparian features may be encountered in the field that have not been identified in the silvicultural prescription or logging plan. In such circumstances, forest harvesting adjacent to the stream, wetland or lake should cease until the appropriate feature is classified and the practice is implemented. For audit purposes and where appropriate, changes should be reflected in an amended silvicultural prescription/logging plan. If environmental damage has occurred, the appropriate government agency should be contacted.
Streams, wetlands, and lakes should not be entered. Instream activities on fish streams, or on stream reaches that could affect fish habitat, or on stream reaches that could affect fish habitat or water quality downstream, may only be undertaken when constraints relative to fish life history or expected streamflows allow. Refer to Appendix 2 for general windows for instream work by regional area and species.
Keep in mind that instream work windows provide a general guide only and do not relieve the proponent of the responsibility to contact local fisheries agencies for information on site-specific mitigation requirements. In addition, although a work period for a particular instream activity may be identified and approved, the proponent should still ensure that the actual work is carried out in a manner that avoids the destruction of fish habitat.
In addition to classified streams, wetlands, and lakes, there are wet depressions or receiving sites that are not classified. The tracks and wheels of ground-based equipment should not be operated within 5 m of any stream, wetland, or lake feature whether classified or not.
Roads within an RMA that are parallel to a stream, wetland, or lake should be designed to minimize short- and long-term impacts on the RMA. This can be done by methods such as minimizing road bed width, minimizing right-of-way width, end-hauling, full bench construction, constructing temporary roads, and deactivating roads after harvesting is completed. Temporary and permanent stream crossings should not damage fish habitat or create blockages to fish passage. This includes small channels that provide access to fisheries-sensitive zones. Temporary stream crossing methods should include crossing streams at right angles and the use of box culverts to avoid damage to streambanks. Temporary crossing sites should have stable banks and avoid instream, stable LWD. Remove all temporary structures once operations are completed. When streambank disturbance is evident and erosion is likely to occur, bank armouring and streamside vegetation must be re-established.
Existing main roads within the RMA can continue to be used. Spur roads within the RMA should be permanently deactivated once they are no longer used.
Streams and side channels should not be artificially channeled to reduce the number of culverts required. Each channel should be adequately culverted. Extra and oversized culverts should be installed where roads cross the active floodplain. In addition, fill heights should be minimized within the active floodplain and the fill protected from erosion. Avoid fill construction on floodplains that parallel the stream.
Falling and yarding should be away from, or parallel to, a stream, wetland, or lake. Cross-stream yarding occurs when a log or portion of a log is yarded over a stream and contacts any part of the bank, channel, or vegetation in the RMA. It is distinguished from full suspension yarding. Cross-stream yarding should normally be undertaken only on S5 and S6 streams following the prescriptions in this guidebook and the Gully Assessment Procedure Guidebook, where streambanks are stable, and where natural LWD in the channel will not be destabilized by the falling and yarding process.
Construction and location of full suspension yarding corridors should minimize removal or modification of trees, especially wildlife trees. Long line yarding cables can significantly damage wildlife trees by knocking off branches and tops of these trees. Long line yarding through RMAs should only occur during periods of low flow or over thick ice to allow removal of debris.
Where falling away from the channel cannot be achieved and the remaining stems threaten channel stability due to windthrow, consider falling across the stream only if the stem will span the stream and can be lifted without damaging streambanks and non-merchantable stems or disturbing stable LWD. Where this cannot be done, address windthrow management according to the section "Windthrow hazard management." When yarding will damage non-merchantable stems, streambanks, or stable LWD, leave that section of stem spanning the channel, providing it is stable and does not obstruct streamflow or fish passage.
When the channel has the capability to transport debris, reduce the impact of logging debris entering the channel from logging operations, including either cross-stream or full suspension yarding, by:
Uphill falling can be hazardous to workers and should be avoided. For all stream riparian classes other than S6, where uphill falling is hazardous, trees in question should be left. For S6 streams:
Where stream clean-out is required it should be carefully supervised to ensure only unstable debris is removed and placed above the high-water level. Removal of stable debris (i.e., debris that is embedded in the channel or is impounding channel bedload) is detrimental to channel stability. The following additional considerations should guide stream clean-out operations:
Fisheries-sensitive zones (FSZs) are side and back channels, ponds, swamps, seasonally flooded depressions, lake littoral zones, and estuaries that are seasonally occupied by over-wintering fish. Fisheries-sensitive zones should be identified and protected by the proponent during forest harvesting operations as follows:
Marine-sensitive zones (MSZs) include herring spawning areas, shellfish beds, marsh areas, existing aquaculture sites, juvenile salmonid rearing areas, and adult salmon holding areas.
Coastal log handling and upland forest harvest operations can damage MSZs. This occurs through:
MSZs should be protected during forest harvesting operations as follows:
Riparian management areas in stands of moderate or high windthrow hazard require special management practices to reduce windthrow potential when logging is proposed within and adjacent to them. Where a reserve zone is required, windthrow hazard management should be designed primarily to protect the reserve zone and only secondarily to protect trees within the management zone.
The Windthrow Handbook for British Columbia Forests (Research Program Working Paper 9401) should be consulted for guidance when assessing windthrow risk or developing prescriptions to reduce the risk of windthrow. Windthrow risk assessments should incorporate local knowledge and experience and should be assessed for the general area and, in greater detail, for each area with significantly different soil depth or drainage, stand structure, and tree species composition. Windthrow risk assessment should be a best judgment interpretation based on an evaluation of regional, local, and site-specific available information.
Windthrow risk is determined by the interaction between factors that affect the force of the wind acting on the tree and factors that affect the resistance of the tree to overturning. Force of the wind is increased by higher wind velocity and turbulence, increased exposure to wind, greater tree height-to-diameter ratio, greater crown size and crown density, and reduced stand density. Resistance to overturning is reduced by poor root anchorage due to saturated soils and restricted rooting depth, occurrence of root or bole rot, extent of interlocking root systems, and past exposure to winds. Soil factors that control rooting depth contribute most significantly to windthrow risk.
High risk stands generally occur where high wind force is likely to occur and resistance to overturning is low. Moderate risk stands occur where root anchorage is poor but wind force is low, root anchorage and wind force is moderate, or root anchorage is good but wind force is likely high. Low risk stands occur where there is a high resistance to overturning and wind force is moderate or low.
Windthrow risk is generally greatest on the windward edge of a stand and decreases a short distance into the stand, although turbulence can result in windthrow several tree heights into the stand. Most windthrow occurs within the first three years following harvesting. However, windthrow risk can increase over time as management activities affect windflow and soil conditions.
Local knowledge is an important consideration when assessing windthrow risk. Certain areas are known to be particularly windy. A history of frequent windthrow and evidence of windthrow or stem breakage in natural stands is an indication that windthrow is likely to occur after harvesting.
Strategies to reduce the risk of windthrow should be considered wherever trees are retained and windthrow risk is moderate or high along all or a portion of the RMA. Windthrow management strategies include locating the tree retention boundary to reduce the risk of windthrow, selecting the most windthrow resistant trees within the management zone for retention, and reducing the force of the wind on the crowns of retained trees. Selected strategies should not only address windthrow risk but also the other values that are being protected in the RMA.
Where windthrow risk is moderate or high in the reserve zone, a sufficient number of trees should be retained within the management zone to protect the windfirmness of the reserve zone. Options include:
– realign RMA boundary to a windfirm edge such as rock bluffs, non-merchantable timber, or soil type change
– leave a buffer at least 20 m wide of well-drained, deep soils between areas of poorly drained or shallow soils of the RMA and the edge of the harvested opening
– where no natural windfirm features are available, consider widening the management zone to a moderate to low windthrow risk stand and align the boundary so that it is at an angle or parallel to the prevailing storm winds
– leave relatively straight boundaries on the outer edge of the RMA; this can be accomplished adjacent to meandering streams by leaving variable width patches of trees in the management zone; do not leave any sharp corners or indentations that are exposed to the wind
– where the management zone is more prone to windthrow than the reserve zone, low tree retention in the management zone may be the most appropriate option.
– feather the outer edge of the management zone by removing trees prone to windthrow; preference should be given to removing the following trees:
~ unsound trees including diseased, deformed, forked, scarred, mistletoe infested, and root rot infested trees; trees with asymmetric or stilt roots; trees growing on unstable substrates such as rocky knolls, large boulders, nurse logs, or wet depressions; tall non-veteran trees, especially those with disproportionately large crowns
Preference for retention should be given to sound, well-rooted veterans (e.g., snag-top cedars) or deciduous trees; sound trees (strong roots and good taper) with relatively small, open crowns; and sound snags when safety is not compromised.
In multi-storied stands, the outer wind-exposed edge of the management zone may be additionally feathered by removing dominant trees from the leading edge, partially retaining codominant trees, and fully retaining suppressed trees within 20–30 m of the edge. This practice is not recommended in single-storied, high density stands.
– top and/or prune (limb) individual trees with a high windthrow risk in the management zone and/or reserve zone; reduce the crown of these trees by 20–30 per cent; topping or pruning in the reserve zones should include only high windthrow risk trees that may cause significant detrimental effects to stream channels or wildlife habitat if they were windthrown;
– combine edge feathering and topping or pruning in high hazard areas.
Options to reduce the risk of windthrow to trees retained in the management zone include topping or pruning (see above) and selection of the most windfirm trees for retention. Trees with the following characteristics tend to be the most windfirm:
When windthrow occurs within a RMA, the remaining standing trees should be left as a protective buffer for other trees of the RMA. Windthrown trees should not be removed from the RMA, as they provide valuable wildlife habitat. Windthrown trees should be removed only if habitat would be improved by their removal and removal will not result in damage to the surviving trees. Windthrown trees should be assessed for removal by a forest health specialist where there is a risk of increasing bark beetle populations and the resultant increase in tree mortality. Windthrown trees that have entered a stream should be removed only if they will destabilize the streambank or channel. Unnecessary removal of windthrown trees from streams can result in significant channel destabilization. All removal of windthrown trees from an RMA must be as specified in an approved silviculture prescription or logging plan.
A wildlife tree is a standing live or dead tree with special characteristics that provide valuable habitat for conservation or enhancement of wildlife (large diameter and height for site, current use, declining or dead, valuable species type, location, and relative scarcity). High quality wildlife trees are frequently present in riparian areas and are used by a variety of species. The proximity of these trees to the edge of streams, wetlands, lakes, and marine-sensitive zones increases their value for some wildlife species. Wildlife trees also provide a source of coarse woody debris used by many riparian species and large woody debris for maintaining stream channel characteristics.
The Biodiversity Guidebook and Managing Identified Wildlife Guidebook provide recommendations for the amount, type, and distribution of wildlife trees to be left within a cutblock and area adjacent to the perimeter of the cutblock. Although wildlife trees should be distributed across the planning area, riparian habitats are priority sites for meeting these recommendations. Not only are high quality wildlife trees present in many riparian areas, but the riparian management area also provides an opportunity for leaving wildlife trees with the least effect on timber harvesting operations.
Reserve zones adjacent to streams, wetlands, and lakes protect many wildlife trees and provide a source of future wildlife trees. However, some wildlife trees within the reserve zone can pose a risk to workers operating in the management zone or the cutblock outside the RMA (see Figure 17). These include standing dead trees that are vertical or lean towards the management zone, as well as some live trees with large dead branches or tops. The best strategy for protecting these trees is for a qualified wildlife tree assessor to mark them as wildlife trees and establish no-work zones around them. The size of the no-work zone will vary by tree and site. Generally, the size of the no-work zone will be one or two tree lengths.
Not all wildlife trees in the reserve zone that pose a risk to workers in the management zone need to be protected by a no-work zone. If wildlife tree requirements have been met outside of the RMA and no eagle, osprey, or great blue heron nest trees or high value wildlife trees are present, wildlife trees deemed hazardous to worker safety within the reserve zone may not need to be protected. Mitigative measures should be taken to protect high value wildlife trees (consult the Wildlife/Danger Tree Assessor's Course Workbook).
When making a determination to remove a wildlife danger tree from a reserve zone, as provided for in the Operational Planning Regulation, a wildlife tree assessment should be completed by a qualified wildlife tree assessor. If a tree is determined to be unsafe and of low wildlife value it may be felled. Trees felled in the reserve zone should be left as coarse woody debris. Trees killed by bark beetles, where beetles remain under the bark, that pose a high risk to adjacent stands should be removed or treated to kill the bark beetles prior to emergence. Trees to be felled should be identified in an approved silviculture prescription and/or logging plan.
All dead wildlife trees that do not pose a risk to workers should be left within the management zone adjacent to the reserve zone or adjacent to the stream, wetland, or lake where no reserve zone is required. Trees retained within the management zone should emphasize wildlife tree attributes. In addition, consider establishing wildlife trees within management zones to meet wildlife tree objectives described in the Biodiversity Guidebook. If harvesting is done by feller buncher, consider felling some wildlife trees at a height near 3 m to create "stubs."
Forest harvesting within the management zone should minimize disturbance to understorey vegetation and avoid damage to remaining trees. Disturbance should be limited to that necessary to achieve successful regeneration.
The following guidelines outline recommendations for silvicultural treatments within the riparian management area:
When selecting treatment options for vegetation management within the RMA, consider the potential impact of the treatment on all resources. The following measures are recommended for all vegetation management applications.
– stream class
– proposed treatment method and herbicide
– distance to S1 to S4 stream reaches or a fish bearing lake
– bank depth; channel width; gradient; months of the year channel is wetted
– composition of bank material (e.g., sand, gravel, boulders)
– bank vegetation community (list species, average height, and percentage of target and non-target susceptible vegetation)
– anticipated recovery of streambank vegetation following treatment (i.e., expected successional process).
The extent of data provided will depend on existing agency and industry information bases and collective experience. This information should be provided by proponents to the BC Environment, Pesticide Management Branch to accompany the pesticide use permit application.
In addition to the general guidelines outlined above, specific measures have been developed for each riparian class, active floodplain, and for large rivers.
A watershed assessment using the the Interior Watershed Assessment Procedure and the Coastal Watershed Assessment Procedure may be required for community watersheds or watersheds with high fishery values (as determined by B.C. Forest Service and BC Environment). The results of these assessments may influence the best management practice within these RMAs. However, "RMA objectives" found in this guidebook should not be compromised. Consult the WAP guidebooks for the specific recommendations that apply.
The principal objective of the management zone of S1, S2, and S3 streams is to maintain the integrity of the reserve zone. A second objective is to protect important wildlife values in the management zone.
Table 5 outlines the objectives and best management practices for the management zones of S1, S2, and S3 streams for both the coast and interior. The principal management zone objective is to reduce windthrow hazard in the reserve zone and the outer edge of the management zone when it is protecting an active floodplain. In addition, the management zone should be managed to protect high value wildlife trees in the reserve zone and, where possible, wildlife values in the management zone. Where the windthrow risk is low and wildlife trees are provided elsewhere, clearcutting to the riparian reserve boundary is an acceptable practice.
Active floodplains (defined in the section "Outer edge of the active floodplain") have special significance for stream channels and fish habitat. Active floodplains typically contain many side channels and old channels, and are an area in which the stream channel frequently realigns. During a single harvest rotation, the stream channel may significantly change its course through the active floodplain. The old cutoff channels and side channels, active during flooding, are often important fish habitat. Fisheries sensitive areas are common within active floodplains. Trees and understorey vegetation on the active floodplain play a critical role in reducing stream current flows during floods, thereby reducing erosion and downstream sedimentation.
Active floodplains also have special significance for wildlife habitat and biological diversity. Although floodplain ecosystems typically occupy a small proportion of the landscape, they contain important habitats and species that are not present in the drier uplands. The diversity of plant and animal species is generally higher than in upland ecosystems and distinct plant and animal communities are present. They also have high value as travel corridors, nesting sites, and feeding areas. Many animals that live in streams also depend on floodplain ecosystems at some stage of their life. Also, high value wildlife trees are common on floodplains. Tree retention objectives, therefore, are higher for floodplain ecosystems in order to maintain these wildlife, stream channel, and fish habitat values.
Stream dynamics and the generally erodible soils of active floodplains require that little or no access road construction occur on these sites, and that low intensity harvesting occurs over a lengthened rotation to retain characteristics of the unlogged stand at all times.
Where an active floodplain is not present and windthrow hazard is low, objectives of the management zone should focus on wildlife values associated with the reserve zone and the moist and drier sites outside the reserve zone. The principal objective is to protect wildlife danger trees in the RMA. Additional objectives include protecting special wildlife features of the management zone and enhancing the habitat values of the reserve zone by providing a transition from the reserve zone to the harvested area outside the RMA. Retention objectives in Table 6 refer to either:
In general, mature trees should be retained over younger trees.
Achieving riparian management area objectives for floodplains of large rivers such as the lower Fraser, Homathko, Kingcome, and Skeena rivers, requires a different management approach than that specified for other stream RMAs. Large rivers are a special category of S1 streams in which woody debris no longer plays the essential role that it does in smaller channels. In smaller channels, trees that enter the stream can span the channel or form jams where it can then contribute to the creation of fish spawning, rearing, and overwintering habitat. A reserve zone is not required adjacent to large rivers and the management zone extends from the streambank to the outer edge of the active floodplain or to 100 m, whichever is greater.
In large rivers, only minor amounts of woody debris found in the stream or along the bank come from the immediate overbank area or are retained along the river's edge. In addition, the role that mature trees play in maintaining bank stability is reduced because the rooting depth of trees is often situated on unconsolidated materials well above the eroding zone of the stream edge. Riparian management guidelines for large river RMAs are distinct from those of other S1 RMAs. It is important that the wildlife riparian objectives are met in the management zone or elsewhere in the landscape on the same river and with similar ecosystems. Landscape level planning should be an essential part of meeting riparian objectives on large rivers.
The following guidelines apply to hardwood management within the RMA on large rivers and their associated active floodplain. Refer to the best management practices outlined in Table 6 (active floodplain) for softwood management.
Table 7. Best management practices for hardwood management tenures* along large rivers – coast and interior
Forest practices in the management zone adjacent to S4, S5, and S6 streams should be planned and implemented to meet riparian objectives including wildlife, fish habitat, channel stability, and downstream water quality.
Tables 8, 9, and 10 outline objectives and best management practices within the management zones of S4, S5, and S6 streams for the coast. Tables 11, 12, and 13 apply to the interior.
The following guidelines apply to the management zone of all wetlands (W1 to W5) and lakes (L1 to L4).
The objectives of the management zone adjacent to wetlands and lakes is to protect the integrity of the reserve zone where one is required, and to maintain important wildlife values where no reserve zone is required.
Tables 14 through 16 outline guidelines for management zones adjacent to all wetlands and lakes. Wetlands and lakes have been separated according to their frequency on the landscape. In biogeoclimatic units where wetlands and lakes are uncommon, individual wetlands or lakes have greater importance for wildlife than where they are common.
Retention percentages for the management zone for dominant and codominant trees in Tables 14, 15, and 16 are for the harvest area (cutblock) and not the entire wetland RMA. Residual trees should be concentrated near the wetland or reserve zone but should also be used to provide no-work zones to protect wildlife hazard trees, and other wildlife features such as trails, moist sites, and deciduous patches.