CDC Logo

BC Conservation Data Centre: Conservation Status Report

Tsuga heterophylla - Abies amabilis / Struthiopteris spicant
western hemlock - amabilis fir / deer fern

 
Scientific Name: Tsuga heterophylla - Abies amabilis / Struthiopteris spicant
English Name: western hemlock - amabilis fir / deer fern
   
Provincial Status Summary
Status: S3
Date Status Assigned: April 21, 2010
Date Last Reviewed: January 16, 2020
Reasons: This forested ecological community is uncommon across a large range. A moderate to excellent percent of the area occupied by the ecological community is identified as old forest. Timber harvest and subsequent fragmentation of remaining area of this ecological community contribute to both short and long-term declines. Timber harvest, climate change impacts, and road-related disturbance contribute to a High threat rating and may contribute to declines of yellow cedar in the CWHvm2. A portion of the range of this ecological community occurs within the Great Bear Rainforest. Within this area, management strategies are anticipated to reduce timber harvest threats to this ecological community. However, ongoing timber harvest on Vancouver Island and the South Coast is expected.
 
Range
Range Extent: F = 20,000-200,000 square km
Range Extent Estimate (km2): 37625
Biogeoclimatic Unit: CWHvm1/06
CWHvm2/06
Range Extent Comments: The range of this ecological community is based on Version 11 of the Biogeclimatic Ecosystem Classification (BEC) map (B.C. Ministry of Forests, Lands and Natural Resource Operations, Biogeoclimatic Ecosystem Classification Map Version 11. 2016). This ecological community has large range that extends across Vancouver Island and the coast of B.C.
Area of Occupancy (km2): GH = 500-20,000 kmē
Area of Occupancy Comments: Terrestrial Ecosystem Mapping (TEM) covers 61% (22 949 km2) of the range (B.C. Ministry of Environment, Terrestrial Ecosystem Information System Database (a), accessed 01/02/2020). This ecological community is identified in 6% (1405 km2) of the mapped area (B.C. Ministry of Environment, Terrestrial Ecosystem Information System Database (b), accessed 01/02/2020). If this proportion of occupancy is extrapolated across the range, the ecological community is estimated to occupy approximately 1405 to 2257 km2.
Spatial Pattern: Large patch
 
Occurrences
Number of Occurrences: Rank Factor not assessed
Number of Occurrences with Good Viability / Ecological Integrity: Rank Factor not assessed
Percent Area with Good Viability / Ecological Integrity: DF = Moderate to excellent (>10%)
Comments: Structural stage information is available for approximately 17% (236 km2) of the area mapped as this ecological community (B.C. Ministry of Environment, Terrestrial Ecosystem Information System Database (b), accessed 01/02/2020). Within polygons identified as this ecological community that also had structural stage information, approximately 0.9% (13 km2) are mapped as mature (structural stage 6) and 11% (154 km2) as old forest (structural stage 7). Since the time of mapping, an additional 25% (948 km2) of polygons of this community were harvested (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Consolidated Cutblocks Database, accessed 01/02/2020) and so the area with good ecological integrity is likely lower than what is indicated by mapping.
Vegetation Resource Inventory (VRI) projected age data is available for 94% (3242 km2) of polygons that contain this ecological community. Approximately 61% (2124 km2) of these polygons with age data are greater than 80 years old, and 48% (1655 km2) of polygons were greater than 250 years old (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Vegetation Resource Inventory, accessed 01/02/2020).
 
Threats (to population, occurrences, or area affected)
Degree of Threat: B = High
Comments: Cumulative threats to this ecological community warrant a High threat rating.

Forest harvesting is calculated as a Medium threat to this ecological community. Both the Results and the Consolidated Cutblocks database indicate that 954 km2 (25%) of polygons mapped with this ecological community has been harvested in the past 40 years (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Results Database, accessed 01/02/2020). Approximately 15% (37625 km2) of the range has been harvested, indicating that this ecological community is targeted within its range for its relatively high productivity. Occurrences of this ecological community in the CWHvm2 are expected to be targeted by harvest as there is a relatively higher cover of yellow cedar. Timber harvest trends are expected to be ongoing on both private and crown land and will likely occur both in old forests and second growth stands. Harvest of old stands will reduce the area with good viability, while the harvest of second growth stands will reduce the area that can recover from previous disturbances.

Climate change is calculated as a Medium-Low threat. Annual precipitation is expected to increase by 4%, though summer precipitation is expected to decrease by 3% (PCIC Plan2Adapt Online Tool, accessed 01/02/2020). These changes may lead to relatively longer dry periods during the growing season, and may extend recovery after disturbance. Spring winds with an intensity to damage forests are expected to increase in coastal areas (Haughian et al. 2012). Wind damage may be significant in instances where the surrounding forest matrix does not confer protection when in early seral stages. Winter precipitation is projected to increase by 3% during the 2020's (PCIC Plan2Adapt Online Tool, accessed 01/02/2020). Extended dry periods may prolong vegetation recovery after disturbance. Altered soil drainage and snow depth attributed to climate change are expected to influence ongoing yellow-cedar (Xanthocyparis nootkatensis) mortality, especially in the CWHvm2 (Hennon et al. 2012).

Roads and road construction are a Low threat to this ecological community. Within TEM polygons mapped with this ecological community, the Digital Road Atlas identifies a moderate-low density of resource roads (1.3 km/km2) (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Digital Road Atlas, accessed 01/02/2020). Roads can contribute to fragmentation and spread invasive alien plant species.
Fires are infrequent and present Low threats to this ecological community. Approximately 3.2% (1220 km2) of the range has recorded fire history (B.C. Ministry of Forests, Lands, and Natural Resources Operations. Fire Perimeters - Historical, accessed 01/02/2020). Fire severity and extent may increase during drier summers.
 
Trend (in population, range, area occupied, and/or condition of occurrences)
Short-Term Trend: F = Decline of 10-30%
Comments: Vegetation Resource Inventory (VRI) projected age data is available for 94% (3242 km2) of polygons that contain this ecological community. Approximately 26% (898 km2) of these polygons with age data are less than 50 years old (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Vegetation Resource Inventory, accessed 01/02/2020).

Terrestrial Ecosystem Mapping (TEM) covers 61% (22 949 km2) of the range of this ecological community (B.C. Ministry of Environment, Terrestrial Ecosystem Information System Database (a), accessed 01/02/2020). Structural stage information is available for 17% (236 km2) of the area mapped as this ecological community (B.C. Ministry of Environment, Terrestrial Ecosystem Information System Database (b), accessed 01/02/2020). Within polygons identified as this ecological community that also have structural stage information, 4% (55 km2) are mapped as Pole/Sapling and younger (structural stage 4 and below).

Approximately 25% (962 km2) of polygons that contain this community were harvested in the recent past (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, RESULTS Openings Database, accessed 01/02/2020) and so the area in younger structural stages is likely higher than what is indicated by mapping. However, the Results database is not considered reliable for harvesting that occurred more than 20 years ago. As well, timber harvest data may be missing because the Results database does not record harvesting when it occurs on private land, and harvesting and stand age for harvested areas are not consistently recorded in the Vegetation Resource Inventory database.

The RESULTS database indicates that 15% (5778 km2) of the range has been harvested. Baseline Thematic Mapping indicates that 13% (4843 km2) of the range has been logged within the past 20 years.
Due to the relatively remote range of this ecological community, conversion to urban land cover likely occurred in the past 50 years and covers less than 0.01% (2 km2) of polygons mapped with this ecological community. Urban land covers less than 1% (51 km2) of the range of this ecological community (B.C. Ministry of Forests, Lands and Natural Resource Operations, Baseline Thematic Mapping, accessed 01/02/2020).
Long-Term Trend: E = Decline of 30-50%
Comments: Vegetation Resource Inventory (VRI) projected age data is available for 94% (3242 km2) of polygons that contain this ecological community. Approximately 61% (2125 km2) of these polygons with age data are greater than 80 years old, and 48% (1655 km2) are older than 250 years (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Vegetation Resource Inventory, accessed 01/02/2020).

Terrestrial Ecosystem Mapping (TEM) covers 61% (22 949 km2) of the range of this ecological community (B.C. Ministry of Environment, Terrestrial Ecosystem Information System Database (a), accessed 01/02/2020). Structural stage information is available for 17% (236 km2) of the area mapped as this ecological community (B.C. Ministry of Environment, Terrestrial Ecosystem Information System Database (b), accessed 01/01/2020). Within polygons identified as this ecological community, approximately 1% (13 km2) is mapped as mature (structural stage 6) and 11% (154 km2) as old forest (structural stage 7) before accounting for timber harvest.

Approximately 25% (954 km2) of polygons that contain this community were harvested (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, RESULTS Openings Database, accessed 01/02/2020). However, timber harvest data may be underestimated because the RESULTS database does not record harvesting when it occurs on private land, and harvesting and stand age for harvested areas are not consistently recorded in the Vegetation Resource Inventory database.

Across the range of this ecological community, Baseline Thematic Mapping indicates that no area has been permanently converted to urban or rural land cover, and the area attributed to mining activities is negligible (B.C. Ministry of Forests, Lands and Natural Resource Operations, Baseline Thematic Mapping, accessed 01/02/2020).

Within polygons mapped with this ecological community, the Digital Road Atlas identifies a moderate ? low density of roads (1.3 km/km2) and 1 km/km2 across the range of the ecological community (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Digital Road Atlas, accessed 01/02/2020). Most roads are classified as resource roads within both polygons mapped as this ecological community and the range. Roads contribute to fragmentation and the spread of invasive alien plant species.
 
Other Factors
Intrinsic Vulnerability: AB=Highly to moderately vulnerable.
Comments: Research on other coastal forests indicates that ecosystem recovery for major plant species occurs approximately 80 years after harvesting. Full recovery will take much longer than 80-100 years as many plant species remain absent at this time (Banner and LePage 2008). For forest structure, a critical component that supports biodiversity, a significant amount of recovery occurs by 80-100 years. Full recovery of old growth characteristics will take 160-200 years (LePage and Banner 2014).
Environmental Specificity: C=Moderate. Generalist or community with some key requirements scarce.
Comments: This ecological community gleyed soils, or thick mors over bedrock where there is constant lateral seepage.
Other Rank Considerations: Provincial Parks and protected areas cover 6% (2323 km2) of the range of this ecological community (B.C. Ministry of Environment and Climate Change Strategy, BC Parks, Ecological Reserves, and Protected Areas, accessed 01/02/2020).

Private land ownership covers 17% (812 km2) of the range of this ecological community (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Integrated Cadastral Fabric, accessed 01/02/2020).

Terrestrial Ecosystem Mapping is generally not available from private land or from Provincial Parks, and timber harvest data is generally not available from private land.

The Great Bear Rainforest Land Use Order covers 42% (15746 km2) of the range of this ecological community (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Special Protection Area, accessed 01/02/2020). The Order sets old forest targets by site series group for the entire Great Bear Rainforest, and these targets would be extended to this ecological community. However, approximately 10% (1501 km2) of the Great Bear Rainforest is identified as previously harvested within the Results database (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, RESULTS Openings Database, accessed 01/02/2020).
 
Information Gaps
Research Needs: Impacts of climate change.
Inventory Needs: Confirm occurrences of ecosystem mapping, including younger age classes as possibly including older trees in stunted form.
 
Stewardship
Protection:
Management:
 
Version
Author: Cameron, E.
Date: January 16, 2020
 
References
B.C. Ministry of Forests, Lands, and Natural Resource Operations. Biogeoclimatic Ecosystem Classification (BEC) Map, WHSE_FOREST_VEGETATION.BEC_BIOGEOCLIMATIC_POLY [ESRI ArcSDE format]. Version 9. Ministry of Forests, Lands, and Natural Resource Operations, Forest Analysis and Inventory Branch, Victoria, B.C. Updated Regularly.
Banner, A., W. MacKenzie, S. Haeussler, S. Thomson, J. Pojar, and R. Trowbridge. 1993. A field guide to site identification and interpretation for the Prince Rupert Forest Region. B.C. Minist. For., Res. Branch, Victoria, B.C. Land Manage. Handb. No. 26.
Green, R.N., and K. Klinka. 1994. A field guide to site identification and interpretation for the Vancouver Forest Region. B.C. Minist. For., Res. Branch, Victoria, B.C. Land Manage. Handb. No. 28.
Meidinger, D. et. al. 2001. Unpublished notes from rare plant community ranking review, March, 2001.
Nuszdorfer, Fred. 1992. Ranking coastal zones: Meeting with Fred Nuszdorfer, May 30, 1992. Lac LaJeune, BC.
 

Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.

Suggested Citation:

B.C. Conservation Data Centre. 2020. Conservation Status Report: Tsuga heterophylla - Abies amabilis / Struthiopteris spicant. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 13, 2026).