|
|
March 2008 Submitted
by B.A. Blackwell & Associates
Ltd. Submitted to Judy Millar Mountain Pine Beetle Specialist BC Ministry of Environment |
Executive Summary
This project was initiated based on a
coarse scale mountain pine beetle (MPB) impact assessment of 88 BC Parks in
2005 (B.A. Blackwell & Associates Ltd. 2005).
The objectives of this impact assessment were to:
- Identify impacts on Park values resulting from mountain pine beetle attack;
- Assess impacts over time and space;
- Provide a reasonable assessment of impact given limited data, time and resources;
- Provide results that can be used for future planning; and,
- Develop recommendations for mitigation strategies and budgeting at the Park level.
The methods employed to meet these objectives utilized existing MPB pine kill projection modelling data, various inventory data available for the Park and expert opinion to derive predictions of impact. The project was broken down into three phases:
- Anal
- Anal
- Final impact overlay and recommended actions.
Primary impact was defined as the direct impact of mountain pine beetle caused tree mortality and was used to identify where pine mortality resulted in changes in openness or in pine composition. These two primary impacts were used to define the ‘area of primary impact’ within which secondary impacts could be assessed.
Secondary impact was defined as the impact
on park values resulting from one of two activity alternatives in response to
primary impacts: 1) do nothing; and, 2) remove hazard trees. A stepped impact
matrix was used to scope Park values and potential impacts on those values for
inclusion in the anal
The significance of each of the values was considered within the Park boundary only, as this is where BC Parks has jurisdiction. Therefore, this assessment does not reflect the significance of these values outside the Park where different management objectives apply. This assessment is coarse scale given the available data and its results are not field tested. In all cases, predicted impacts are simplified representations of complex effects. This assessment is a suitable tool for broad strategic planning but is not appropriate for planning at the operational level. In addition, it is possible that values at risk not captured in this assessment may exist at the site level. Verification of actual or potential impacts by qualified professionals is required in the field prior to any activities being planned. Data should not be mapped at a scale larger than 1:50,000 as this is the lowest reported accuracy of the input data.
The final impact overlay provided a spatial definition of impact within the park based on identified values judged to be impacted by ‘Do nothing’ or ‘Remove Hazard Trees’. The results of the spatial overlay defined where different actions were recommended based on the secondary impacts that occurred in each location. The area totals were as follows:
- Hazard Tree Removal: 1,241 ha area of hazard tree removals reflected the significant predicted impact on public safety.
- Mitigate:1,665 ha area of mitigation reflected where the impact on red-listed species, invasive plant species, visual quality, special features, fuel hazard and cultural features was predicted to be significant.
- Monitor: 17,463 ha area of monitoring reflected where impact on structural stage, peak flows, terrain stability, surficial erosion and sedimentation, stream temperature and shading and riparian habitat was predicted to be significant.
- Monitor Uncertainty: 29,512 ha area of monitoring uncertainty reflected the area of all values within the park for which significance could not be determined.
Overall, results indicated that impacts are concentrated in the eastern portion of the park and through the highway corridor. However, substantial areas of trails and high-use areas throughout the Park are impacted. The large areas of “monitor uncertainty” and “monitor” reflect knowledge and data gaps that exist both in terms of data available for the Park and expected impacts of MPB on Park values.
The recommendations made based on the
results of the anal
1) Increase the frequency of hazard tree assessments in areas where public safety, special feature or cultural feature impacts have been identified as significant or uncertain and concern has been confirmed on-site by a qualified professional.
2) Where hazard tree removals are planned to occur consider the following:
a) In areas with high pine mortality, consider removing a percentage of dead pine trees (even if not technically assessed as hazardous) to achieve an incremental reduction in dead pine volume. The percentage could be varied to maintain the aesthetic and environmental integrity of the area but should reduce the likelihood of a future spike in resource requirements for hazard tree removals.
b) If peak flows or erosion/sediment delivery impacts are predicted to be significant and concern is confirmed on-site by a qualified professional, consider doubling riparian reserve zone widths and leaving slash on the ground unless it amounts to more than 5kg/m2 over an area of 100 m2.
c) If terrain stability impacts are predicted to be significant and concern is confirmed on-site by a qualified professional, consider consulting a Professional Geologist to determine whether special removal methods are required.
d) If invasive species, red-listed species, cultural features or special features are predicted to be significant and concern is confirmed on-site by a qualified professional, modify tree removal methods or boundaries to protect those values.
e) If fuel hazard impacts are predicted to be significant and concern is confirmed on-site by a qualified professional, ensure that retained CWD is bucked and generally left lying flat to the ground (not elevated). Where slash exceeds 5kg/m2 over an area of 100 m2, consider piling and burning to reduce fuel load.
f) Undertake tree removals in winter where possible to minimise potential hydrological, terrain stability and soil disturbance impacts.
g) Design tree removals to minimize windthrow hazard by determining the susceptibility of residual tree species, historic windthrow patterns, topographic features and soil types and conditions. The MoFR procedure (Windthrow Field Card FS 712-2) could provide a suitable assessment method.
h) If hazard tree removals in a riparian reserve zone are necessary, consult a fisheries biologist regarding potential mitigation strategies.
i) If the riparian area consists of primarily dead pine (>60%), consult a fisheries biologist to determine whether rehabilitation of the riparian area is desirable.
j) Retain species other than lodgepole pine unless they are identified as a hazard.
k) Minimize damage to retained trees and understory vegetation.
l) Leave slash greater than 15 cm in diameter on the ground unless it amounts to more than 5kg/m2 over an area of 100m2.
m)
Follow the Riparian Management
Area Guidebook (
n) Avoid any mechanical or other disturbance in or within 20 m of S3 and S4 streams.
o) Create tall stumps or stubs (3 to 5 m tall) as cavity sites where they do not create a worker safety or wildfire hazard.
p) Retain CWD on site in a way that mimics its natural distribution of randomness and connectivity. Retain 2 to 5 pieces of greater than 12 cm dbh per square metre.
q) Plan the timing of treatments to avoid disrupting applicable wildlife using the habitat. For example, avoid treatments in late winter/heavy snow years if ungulates are utilizing the site because the canopy is providing snow interception, or in spring/early summer during the nesting period.
r) Stubs should be restricted to trees greater than 30 cm in dbh or where cavities already exist.
s) When re-forestation is required, re-plant as soon as possible following treatment.
3) Consider increasing the frequency of culvert and bridge assessments in areas where peak flow and surficial erosion/sediment delivery have been identified as significant or uncertain and concern has been confirmed on-site by a qualified professional.
4) Given the temporary nature of MPB related impacts, the frequency and intensity of any monitoring that takes place within the Park should be determined based on Park management priorities. As a result, no specific schedule or standard is recommended in this report. The values for which monitoring was recommended include surficial erosion, stream temperature and shading, terrain stability, structural stage distribution, and riparian habitat. In all cases where uncertainty was identified, the recommendation is monitoring to address uncertainty. The exception to that statement is areas of uncertainty regarding public safety; the current annual parks wildlife danger tree assessment process is considered adequate to address uncertainty in these areas and should be maintained. If assessments identify dead pine in these areas, then the public safety impact is considered ‘significant’ and recommendations 1 and 2 apply.
5)
Consider working towards
filling knowledge gaps that inhibit the ability to plan with certainty in the
Park. Terrestrial Ecos
Acknowledgements
The authors would like to thank the following individuals for their contributions to the project:
Judy Millar and Kirk Illingworth of the
Ministry of Environment provided valuable
Grant MacHutchon and Damian Power provided
the reports used to source habitat suitability index ratings for ecos
Rob Scagel implemented the projected pine kill model on the Park’s vegetation inventory data.
Table of Contents
2.1.1 Change in Pine
Composition
Sediment Delivery/Surficial Erosion
Stream Temperature and Shading
Red Listed Species Occurrences
Mule Deer and Black Tailed Deer
2.3 Final Impact Overlay
and Recommended Actions
3.1.1 Change in Pine
Composition and Openness
3.2.2 Sediment
Delivery/Surficial Erosion
3.2.3 Stream Temperature and
Shading
3.2.6 Structural Stage
Distribution
3.3 Overlay of Secondary
Impacts and Recommended Management Responses
4 Assumptions, Limitations
and Future Considerations
List of Figures
Figure
1. Summary of methodology
Figure 2. Average cumulative kill percentages for
projected pine mortality within the Park.
Figure 3. Average % change in pine composition and %
change in openness across the Park over time.
Figure 4. Representation of fire hazard succession
following mountain pine beetle attack.
List of Tables
Table
1. Classification of pine composition.
Table 2. Classification of forest openness.
Table 3. E.C. Manning Provincial Park stepped impact
matrix
Table 4. Percent of Park area with watersheds potentially
impacted by peak flow increases.
Table 5. Macro Stream Reaches with <20% forest cover
over >10% of their length.
Table 7. Riparian management areas where <60% of the
RMA has >20% forest cover post-MPB attack.
Table 8. Invasive species found in the Park and vector
matrix information.
Table 9. Summary of fuel hazard impact resulting from MPB
attack in the Park.
Table 10. Estimated area where public safety is predicted
to be impacted by MPB attack.
Table 11. Estimated length of named trails potentially
impacted by MPB.
Table 12. Estimated area where special features are
predicted to be impacted by MPB attack.
List of Maps
Map
1. Biogeoclimatic Ecosystem Classification within E.C. Manning Provincial Park.
Map 2. Change in pine composition from 1999 to 2024 (only
considers stands with a pine component).
Map 3. Change in openness over time from 1999 to 2024
(only considers stands with a pine component).
Map 4. Overall primary impact area.
Map 10. Sections
of riparian habitat predicted to be potentially impacted by MPB attack.
Map 15. Clark’s nutcracker potentially suitable habitat
potentially impacted by MPB.
Map 16. Areas where fuel hazard is predicted to be
potentially significant based on MPB impact.
Map 17. Areas where public safety is predicted to
potentially be impacted by MPB attack.
Map 18. Areas where special features are predicted to be
potentially impacted by MPB attack.
Map 19. Location of cultural features that are predicted
to be potentially impacted by MPB.
Map 20. Areas where visual quality is predicted to be
potentially impacted by MPB attack.
Map 21. Final impact overlay delineating areas for
recommended actions.
1 Introduction
BC Parks has a mandate to manage for ecos
Numerous insects and diseases are active
within
The mountain pine beetle (Denroctonus ponderosae Hopk.) (MPB) is
responsible for the largest recorded natural disturbance to occur both in
A coarse scale mountain pine beetle impact
assessment was completed for 88 BC Parks in 2005 (B.A. Blackwell &
Associates Ltd. 2005). The project quantified current and future impacts of the
beetle on forested landscapes and related those impacts to the values that each
Park was managed for. This was a coarse scale anal
1.1 Project Objectives
The objectives of this impact assessment are to:
1) Identify impacts on Park values resulting from mountain pine beetle attack;
2) Assess impacts over time and space;
3) Provide a reasonable assessment of impact given limited data, time and resources;
4) Provide results that can be used for future planning; and,
5) Develop recommendations for mitigation strategies and budgeting at the Park level.
1.2 Study area overview
The Park is situated in a transitional zone influenced by both the coast and interior climates and climatic conditions vary greatly across the area. In general the climate may be described as ‘Humid Continental’ dominated by mild, moist pacific air most of the year. The western part of the study area experiences a relatively wet and mild climate typical of the coast. The eastern portion experiences more severe conditions of temperature and extended periods of drought which are characteristic of the interior climate.
A number of biogeoclimatic ecos
Numerous tree species occur within the Park
due to the diversity of ecos
Map 1.
Biogeoclimatic Ecos
2
Methodology
The project was broken down into three phases:
1.
Anal
2.
Anal
3. Final impact overlay and recommended actions.
Primary impact was defined as the direct impact of mountain pine beetle caused tree mortality.
Secondary impact was defined as the impact on park values resulting from one of two activity alternatives in response to primary impacts: 1) do nothing; and, 2) remove hazard trees.
Figure 1 summarizes the methodology of the impact assessment.
2.1 Primary Impact
The primary impacts considered were:
- Change in pine composition; and
- Change in openness.
|
Figure 1. Summary of methodology |
Initially, change in forest composition from conifer dominated to mixed or deciduous dominated forest was also considered; however, a review of the results indicated that very few areas of the Park were affected by this type of change and the outcome of the primary impact layer was not judged to be sensitive to the inclusion of this layer. Therefore, it was assumed that the primary area of impact due to MPB attack was adequately described by change in pine composition and change in openness.
The primary impact layers (change in pine
composition and change in openness) were developed using lodgepole pine
mortality projections from year 3 of the provincial-level projection of the
current mountain pine beetle outbreak[2]
(Eng et al. 2006) and overlaying
these with forest attributes extracted fro
Cumulative beetle kill scenarios were analyzed for years 1999 to 2024. Each forest cover polygon was assigned an averaged cumulative kill percentage and classified according to the following forest attributes for each beetle kill scenario: 1) pine composition (stand pine composition); and, 2) openness (as measured by changes in canopy cover).
Three beetle kill scenarios were used to assign impact ratings to each of the primary impacts. These were: 1) Pre-attack stand (stand status pre-attack from VRI); 2) 2024 projected cumulative kill (projected percentage of pine removed from the stand); and, 3) 100% pine kill (assuming 100% pine removed from the stand). The change between pre-attack stands (1) and 2024 projected stands (2) was used to derive ratings of high, moderate and low primary impact. Uncertainty was accounted for by incorporating 100% pine kill (3) into the layer as an additional rating. For example, if there was no change between the pre-attack and 2024 model results but the 100% pine kill results indicated a change, then the polygon was assigned to ‘uncertainty’.
The purpose of the ‘uncertainty’ rating was to capture areas where primary impacts may occur but are not modelled to occur. In addition, model results for beetle kill were averaged based on their spatial location relative to VRI polygons, therefore, beetle kill may potentially be over- or under-estimated within each polygon. The incorporation of uncertainty using 100% pine kill provides an estimate of uncertainty where impact maybe under-estimated and therefore enables a conservative overall estimate of impact. Given the lack of data on the impact of MPB attack in BC Parks, a conservative estimate (i.e., one that incorporates the worst case scenario of 100% pine kill as uncertainty) was judged to be an appropriate approach given the values at risk.
Time was incorporated into the anal
2.1.1 Change in Pine Composition
The pine composition attribute was a measure of the residual pine composition following beetle attack. It captured the amount of pine that remained in the stand. The pine composition classification is summarized in Table 1.
Table 1. Classification
of pine composition.
|
Class |
Pine
component of stand |
|
No pine |
< 10% |
|
Minor pine |
>/= 10% and < 20% |
|
Mixed pine |
>/= 20% and < 50% |
|
Leading pine |
>/= 50% |
The ratings assigned based on the change
fro
- High: Leading pine class to minor or no pine class
- Moderate: Leading pine class to mixed pine class / Mixed pine class to no pine class
- Low: Mixed pine class to minor pine class / Minor pine class to no pine class
Uncertainty was assigned when 100% pine kill indicated a change that was different from the 2024 result.
2.1.2 Change in openness
The change in openness attribute was a measure of the change in canopy cover following beetle attack. The openness classification is summarized in Table 2.
Table 2. Classification of forest openness.
|
Class |
Canopy
Cover |
|
Non-forested |
0% |
|
Open |
< 20% |
|
Partial |
20% < 60% |
|
Closed |
>/= 60% |
The ratings assigned based on the change
fro
- High: Closed class to Open or Non-forested class
- Moderate: Closed class to Partial class/ Partial class to Open
or Non-forested class
- Low: Open class to Non-forested class
Uncertainty was assigned when 100% pine kill indicated a change that was different from the 2024 result.
2.1.3 Area of Primary Impact
The change in pine composition and change in openness ratings were combined spatially to derive an overall assessment of primary impact. Uncertainty was assigned when it was carried through from both primary impact values.
Numeric values were assigned to High (3), Moderate (2) and Low (1) ratings for both ‘change in openness’ and ‘change in pine composition’. The values were then summed to derive ‘primary impact’. Primary impact value was defined as follows:
- Low = 1 or 2
- Moderate = 3 or 4
- High = 5 or 6
- Uncertainty = uncertainty exists in both primary impacts
The creation of the overall primary impact layer was based on the assumption
that portions of the Park that have had or will experience the greatest change
in openness and/or pine composition due to pine mortality are representative of
the areas in the Park most impacted by MPB attack. The area of primary impact defines
the spatial area of impact and the uncertainty in the area of impact.
2.2 Secondary Impacts
2.2.1 Scoping
Scoping is defined as the process used to
identify the issues and impacts that are likely to be important in an impact
assessment. In order to determine which secondary impacts may occur, it was
necessary to identify the potential activities that would take place in the
Park to address primary impacts. Given the BC Parks mandate to maintain natural
ecos
- Do nothing (the default state); or,
- Remove hazard trees (where public safety is at risk).
Either one of these activities could then be assessed based on its impact on values at risk to determine whether impacts were ‘significant’ and therefore whether mitigative actions were required.
Values at risk were identified either as
Valued Ecos
An important assumption that underlies the assessment of secondary impacts is that any tree removal activities will not result in any new area of permanent access or conversion to non-forest (access and fragmentation have not been considered as impacts). Any tree removal that takes place will only be to remove dead pine and hazard trees, no other tree species will be modified.
The VEC/VSCs were selected based on Park management values and available data. Initially, an extensive list of potential impacts was prepared. Then, based on available data and expert opinion, the list was reduced down to a manageable number (Table 3) of values that either directly or indirectly represented potential impacts on the Park. The criteria used to select VECs/VSCs were as follows:
- The value reflects Park management objectives;
- The value is likely to provide a direct or indirect measure of impact by MPB attack or subsequent tree removals;
- Adequate data exists to define the value within the Park;
- Adequate data or knowledge exists to make a prediction on the magnitude of change in the value and the significance of the impact.
Values that did not meet these criteria
were excluded from the anal
Table
3.
|
|
Type
of Action |
Condition |
|||
|
Values |
1. Take no action |
2.
Remove dead/ hazard trees |
Initial |
Change |
Predicted
Impact |
|
Peak Flow |
X |
X |
Reduced forest
cover |
Snow
interception decreases |
Peak flows are
increased |
|
Sediment
delivery/surficial erosion |
X |
X |
Reduced forest
cover |
Increased bare
ground exposure to precipitation |
Surficial
erosion/sediment delivery is increased |
|
Stream
temperature and shading |
X |
X |
Reduced forest
cover |
Increased ground
and channel exposure to radiation |
Stream
temperatures are increased |
|
Terrain
Stability |
X |
X |
Death/removal of
trees |
Roots decay |
Terrain is less
stable |
|
|
X |
X |
Death/removal of
old growth trees |
|
Less abundance
of old seral stages |
|
Structural stage
distribution by |
X |
X |
Death/removal of
trees |
Structural stage
distribution is altered |
Increased
abundance of early-mid seral stages |
|
Riparian |
X |
X |
Removal of trees |
Disturbance of
riparian habitat |
Degraded riparian
habitat |
|
Invasive Species |
|
X |
Mechanical
disturbance of site |
Dispersal of
invasive species onto site |
Invasive species
established on site |
|
Red-listed
Species Occurrences |
|
X |
Mechanical
disturbance of site |
Potential
disturbance of occurrence |
Species disturbed |
|
Mule/Black-tailed
Deer Habitat |
X |
X |
Death/removal of
trees in habitat |
|
Habitat is
altered |
|
|
X |
X |
Death/removal of
trees in habitat |
|
Habitat is
altered |
|
Bear Habitat |
X |
X |
Death/removal of
trees in habitat |
|
Habitat is
altered |
|
Fuel hazard |
X |
X |
Standing dead
trees |
Red attack/trees
fall or are felled and left on site |
Fuel hazard is increased |
|
Public safety |
X |
|
Standing dead
trees |
Increased
probability of tree failure |
Trees fall |
|
Special features
zones |
X |
X |
Death/removal of
trees |
Falling trees or
removal of trees threatens special feature |
Special feature
is degraded |
|
Cultural
features (archaeological, heritage) |
X |
X |
Death/removal of
trees |
Falling trees or
removal of trees threatens heritage features |
Heritage feature
is degraded |
|
Visual quality |
|
X |
Removal of trees |
Landscape is
modified |
Visual quality
is reduced |
2.2.2 Significance
Determining which changes were considered impacts and the magnitude of the impact required the prediction of significance. The indicators listed in Table 3 were used to predict significance and were based on available data, existing research and expert opinion. The following classifications were used:
- No Impact: If there is no overlap between the activity and the value in space or time the activity is assessed as having no impact.
- Significant Impact: A secondary impact that has the potential to negatively affect the value according to modelled primary impact results.
- Uncertain Impact: A secondary impact that is not predicted to potentially occur based on modelled primary impact results, but that could occur based on the 100% pine kill scenario.
The following tables outline how significance was determined for the impact on each value, the references used to determine the significance thresholds and the assumptions and limitations of the significance thresholds. Significance was then mapped for each impact within the Park.
In
all cases, values that met significance thresholds pre-attack were not
considered ‘significant’ post-attack because the impact was not significant due
to MPB attack.
Peak Flows
|
|
Type of Action |
|
|
|
|
|
|
|
1. Take no action |
2. Remove dead/ hazard trees |
|
|
|
|
|
Values affected by MPB |
|
Condition |
Significance
Threshold |
|||
|
Initial |
Changes |
Predicted
Impact |
|
|||
|
Peak Flows |
x |
x |
Reduced forest
cover |
Snow interception
decreases |
Peak flows are
increased |
Equivalent
Clear-cut Area > 35% of total watershed |
|
|
||||||
|
Data Sources used
to Derive Layer: Community
watersheds (land resoure data warehouse), WSA (watershed atlas) 3rd
order and greater watersheds (LRDW), VRI data (LRDW), cumulative pine kill
(Eng et al. 2006). |
||||||
|
Significance
Thresholds: |
||||||
|
Other: Divide |
||||||
|
Assumptions and
Limitations: Removal of
overstory canopy increases peak flow. Stand volume
reduced by < 30% = 100% hydrological recovery, Volume reduced by >/=
30% </= 60% = 50% hydrological recovery, Volume reduced > 60% = 0%
hydrological recovery. Elevation >800
m therefore No other
potential or recent disturbance within the watershed has been considered. 3rd
order and greater watersheds are an appropriate scale at which to assess the This assessment
was not completed by a professional hydrologist and was not part of a formal
Watershed Assessment Procedure. |
||||||
|
References:
Watershed Assessment Procedure Guidebook (http://www.for.gov.bc.ca/tasb/legsregs/fpc/FPCGUIDE/wap/WAPGdbk-Web.pdf) |
||||||
Sediment Delivery/Surficial Erosion
|
|
Type of Action |
|
|
|
|
|
|
|
1. Take no action |
2. Remove dead/ hazard trees |
|
|
|
|
|
Values affected by MPB |
|
Condition |
Significance
Threshold |
|||
|
Initial |
Changes |
Predicted
Impact |
|
|||
|
Increased risk of
sediment delivery/surficial erosion |
X |
X |
Reduced forest
cover |
Increased bare
ground exposure to precipitation |
Surficial
erosion/sediment delivery is increased |
Slope is >60%
and canopy cover is reduced from >60% (closed) to < 20% (open) |
|
|
||||||
|
Data Sources used
to Derive Layer: TRIM
derived slope raster
(LRDW), WSA 3rd order and greater watersheds (LRDW), community
watersheds (LRDW), VRI data (LRDW), cumulative pine kill (Eng et al. 2006). |
||||||
|
Significance
Thresholds: Slope >60% and
forest cover reduced from >60% (Closed) to < 20% (Open) by 2024
(Significant) Slope >60% and
forest cover reduced from >60% (Closed) to < 20% (Open) assuming 100%
pine kill (Uncertain) |
||||||
|
Assumptions and
Limitations: Areas with >
60% slope are likely to be at risk from erosion. Areas with dense
pine cover killed by mountain pine beetle are likely to have bare ground
exposed following beetle kill until ground cover has had time to establish;
this is likely to be highly variable in reality. No advanced
regeneration in stands. Areas where heavy
pine removal occurs will have bare ground exposed due to mechanical tree
removal. Lack of
appropriate scale surficial geology data requires reliance on >60% slope
as a crude estimate of erosion hazard; some soil types have high erosion
hazard at lower slope gradients. |
||||||
|
References:
Community Watershed Guidebook (http://www.for.gov.bc.ca/tasb/legsregs/FPC/fpcguide/WATRSHED/watertoc.htm);
Mapping and Assessing Terrain Stability Guidebook (http://www.for.gov.bc.ca/hfd/library/ffip/BCMoF1999_C.pdf)
|
||||||
Stream Temperature and Shading
|
|
Type of Action |
|
|
|
|
|
|
|
1. Take no action |
2. Remove dead/ hazard trees |
|
|
|
|
|
Values affected by MPB |
|
Condition |
Significance
Threshold |
|||
|
Initial |
Changes |
Predicted
Impact |
|
|||
|
Stream
temperature and shading |
X |
X |
Reduced forest
cover |
Increased ground
and channel exposure to radiation |
Stream
temperatures are increased |
Canopy cover is
<20% over >10% of the stream length |
|
|
||||||
|
Data Sources used
to Derive Layer: Macro stream
reaches (LRDW), FISS fish occurrences (LRDW), VRI data (LRDW), cumulative
pine kill (Eng et al. 2006) |
||||||
|
Significance
Thresholds: Canopy cover <
20% (open) over 10% of the stream length by 2024 (significant) Canopy cover <
20% (open) over 10% of the stream length assuming 100% pine kill (uncertain) |
||||||
|
Assumptions and
Limitations: Macro stream
reaches with gradients of less than 20% could support fish (sections with
gradients greater than that cannot). Pine may have
been identified in the VRI polygon (source of forest cover estimates) but may
not be present within the riparian corridor due to the scale of mapping. Increased stream
temperature will not necessarily have a negative impact in all cases. |
||||||
|
References:
Riparian Management Area Guidebook (http://www.for.gov.bc.ca/tasb/legsregs/fpc/fpcguide/riparian/rip-toc.htm) |
||||||
Terrain Stability
|
|
Type of Action |
|
|
|
|
|
|
|
1. Take no action |
2. Remove dead/ hazard trees |
|
|
|
|
|
Values affected by MPB |
|
Condition |
Significance
Threshold |
|||
|
Initial |
Changes |
Predicted
Impact |
|
|||
|
Terrain Stability |
X |
X |
Death/removal of
trees |
Roots decay |
Terrain is less
stable |
Slopes >60%
and change in openness from >20% to </= 20% |
|
|
||||||
|
Data Sources used
to Derive Layer: TRIM derived
slope raster, VRI data (LRDW), cumulative pine kill (Eng et al. 2006) |
||||||
|
Significance
Thresholds: Slope >60%
(significant) where change in openness is moderate or high by 2024
(significant) Slope >60%
(significant) where change in openness is moderate or high assuming 100% pine
kill (uncertain) |
||||||
|
Assumptions and
Limitations: Slopes >60%
have a higher risk of landslide following timber harvesting or substantial
reduction in forest cover. No advanced
regeneration in stands. Inadequate data
to produce terrain stability class mapping therefore crude measure of >60%
is used to indicate terrain stability. Will likely
over-estimate areas where terrain stability impact is significant. |
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References:
Mapping and Assessing Terrain Stability Guidebook (http://www.for.gov.bc.ca/hfd/library/ffip/BCMoF1999_C.pdf) |
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Old Forest
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Type of Action |
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1. Take no action |
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