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BC Conservation Data Centre: Conservation Status Report

Pinus albicaulis
whitebark pine

 
Scientific Name: Pinus albicaulis
English Name: whitebark pine
   
Provincial Status Summary
Status: S2S3
Date Status Assigned: March 31, 2013
Date Last Reviewed: April 30, 2019
Reasons: This species occurs in relatively high numbers of individuals over a moderately large range extent in subalpine regions of BC, but it is highly threatened by mountain pine beetle and white pine blister rust epidemics, climatic warming trends, and successional replacement. Short term trends suggest a major decline, but the impacts vary depending on the region in the province and elevation. Some individual trees are resistant to blister rust as well.
 
Range
Range Extent: FG = 20,000-2,500,000 square km
Range Extent Comments: Using GIS tools, the Convex Hull Range Extent is 452,284 sq km. In this analysis, large areas of continuous unsuitable habitat at low elevation in between suitable areas are included in the range.When they are excluded, the range is ca. 145,000 sq km.
Area of Occupancy (km2): HI = 2,501 to >12,500
Area of Occupancy Comments: Summaries of BC Spatial vegetation resource inventory data indicate that Pinus albicaulis occurs over ca. 5610 square km in BC (E. Campbell, pers. comm. 2007). Using the same data, the Index of AOO calculation is 45,420 sq km.
 
Occurrences & Population
Number of Occurrences: U = Unknown
Comments: Pinus albicaulis is a dominant tree in many upper subalpine forests in western North America. This species is frequent in British Columbia occurring almost exclusively in the Engelmann Spruce - Subalpine Fir and the Alpine Tundra biogeoclimatic zone of the Coast-Cascade, Monashee, Selkirk, Purcell and Rocky Mountain Ranges. Neither element occurrence mapping or estimated occurrence data are available.
Number of Occurrences with Good Viability / Ecological Integrity: U = Unknown
Comments: Unknown. However, recent studies done on the impacts of exotic blister rust infections, the recent mountain pine beetle epidemic, and climate change impacts indicate that Pinus albicaulis in British Columbia may be represented by many occurrences in poor condition. Studies examining the distribution and severity of white pine blister rust in Pinus albicaulis (Campbell and Antos 2000; Zeglen 2002), showed half of trees were dead or had active infections.

Aerial surveys of mountain pine beetle infestations indicate widespread beetle infestations and tree death (Campbell and Carroll 2007). Model projections of climate change impacts indicate major losses of suitable habitat for whitebark pine between 2000 and 2070 in British Columbia (Hamann & Wang 2006; Warwell et al. 2006) and near complete losses of habitat in more southern parts of its geographic range in North America (Schrag et al. 2007). Losses of cone bearing branches from blister rust, and tree deaths caused by mountain pine beetle are causing and will continue to cause severe reductions in reproductive potential. Warming climates are also likely to reduce whitebark pine regeneration success through its impacts on seed viability and seedling establishment, but this needs to be studied further (Eila Tillman-Sutela, pers. comm. 2007).
Number of Occurrences Appropriately Protected & Managed: U = Unknown
Comments: 18,698 hectares of white bark pine forests are in protected areas in BC in ESSF, AT, MS, SBS, IDf, and ICH with a threshold presence of greater than or equal to 10 ha cumulative cover (in descending order of % of range in BEC zone)(Chourmouzis et al. 2009). This represents 51 protected areas in ESSF and 14 in AT. 23.8% of the range of whitebark pine that occurs in ESSF is protected (96.01% of the species range is in the zone) and 36.6% of the range that occurs in AT is protected (only 3.99 % of the species range occurs in AT). However, these areas do not provide adequate protection from threats, but they provide opportunities for government agencies to colloborate on strategic management of the species.
Population Size: H = >1,000,000 individuals
Comments: Estimated abundance (number of stems) is 169,452,200 in British Columbia from Campbell (1998)(P. Achuff, pers. comm. 2010; B. Wilson, pers. comm. 2010).
 
Threats (to population, occurrences, or area affected)
Degree of Threat: Substantial, imminent threat
Comments: White pine blister rust (Cronartium ribicola), native to Eurasia and introduced to western North America in 1910, is the most compelling threat to Pinus albicaulis (whitebark pine) throughout its range. Hoff et al. (1980) reported that whitebark pine has low levels of resistance to the blister rust and is several times more suseptible to it than Pinus monticola. Results of two recent surveys (Campbell and Antos 2000; Zeglen 2002) which examined the distribution and severity of white pine blister rust in Pinus albicaulis, showed almost half of trees were dead or with active infection (and likely conservative estimate for active infection).

Whitebark pine is also a host to mountain pine beetle (Dendroctonus ponderosae). While losses due to pine beetle were relatively minor in the past (Campbell and Antos 2000) in BC warming climates have led to an expansion of beetle outbreaks into higher elevation forest containing whitebark pine (Campbell and Carroll 2007). About 7% of forests containing whitebark pine in British Columbia are currently infested by pine beetle (Campbell and Carroll 2007). This represents a tripling of the extent of infestation levels. While most beetle outbreaks are killing nearly all large whitebark pine trees within 3-5 years, occasionally, a single beetle dispersal event will kill nearly all trees within a single year. A small percentage of whitebark pine (3-5%) produce hypersentive bark reactions that enable them to resist mountain pine beetle attack. Given the severity of the current outbreak, beetles have also been observed to attack smaller whitebark pine trees (12-15 cm in diameter), which are generally considered suboptimal habitat for the beetle. Keane and Arno (1993) also reported that whitebark trees stressed by blister rust are more susceptible to attack by mountain pine beetle.

Successional replacement by more shade-tolerant tree species is also contributing to whitebark decline. This seems to have occurred due to fire suppression activities. Campbell and Antos (2003) show substantial reductions in whitebark pine due to competitive exclusion as subalpine stands age and disturbances like beetle outbreaks blister rust infections accelerate this successional process. About 60-70% of stands currently containing whitebark pine in BC are over 200 years old.

Model projections of climate change impacts indicate major losses of suitable habitat (e.g. a 73% reduction) for whitebark pine between 2000 and 2070 in British Columbia (Hamann & Wang 2006; Warwell et al. 2006) and in more southern parts of its geographic range in North America (Schrag, et al. 2007). Campbell and Carroll (2007) project that with continued climatic warming will make 25%whitebark pine range highly vulnerable to future beetle outbreaks. Combined, blister rust, mountain pine beetle outbreaks, and climate change pose a triple threat to this species.

In addition, whitebark pine is being logged in some areas in British Columbia. Logging is not a significant threat on its own, but since logging occurs in healthy stands, it reduces the number of intact stands not yet affected by beetles, which may be important for future survival of this species (E. Campbell, pers. comm. 2007).
 
Trend (in population, range, area occupied, and/or condition of occurrences)
Short-Term Trend: DF = Decline of 10-70%
Comments: Recent data shows short term declines of 10% (Canadian Rockies) to 89% (western portions of the range). However, health trends are quite regional (R. Moody, pers. Comm. 2010). Province-wide average declines are unknown.

Whitebark pine mortality from white pine blister rust between 2003/2004 and 2009 for plots in North, central and South regions in the Canadian Rockies was 18% and 28% respectively (COSEWIC 2010c), representing a 10% decline in individuals.

In west central BC on the eastern slopes of the coast ranges, between 1978/1985 and 2007/2009, 81% of mature whitebark pine trees have died (measured as the number of stems per hectare, loss of 72%)(Haeussler et al. 2009; Haeussler pers. comm., 2011; Clason pers. comm., 2011; Vinnedge pers. comm., 2011).White pine blister rust Infection rates were also as high as those reported by Campbell and Antos (2000) and Zeglen (2002). Following canopy mortality, dramatic increases in shade-tolerant conifers were also observed raising concerns about successional replacement as well. In addition, whitebark pine was found to be regenerating poorly in burns in west central BC. A trial in McKendrick Pass measured 6 times between 1996 and 2007 shows that 89% of all whitebark pine trees were infested with blister rust and the mortality rate of seedlings and saplings was 10% per year.

There are healthy stands around Lillooet where conditions are drier and the blister rust does poorly (R. Moody, pers. Comm., 2010). In the Flathead Region, at higher elevations trees are less impacted as both rust and beetle do poorer at the highest sites. Individual trees that are resistant to the rust can be found in areas that are devastated as well.
Long-Term Trend: DH = Decline of <70% to increase of <25%
Comments: Although not documented, this species has likely declined significantly over the long-term due to mortalities from white pine blister rust and moutain pine beetle.
 
Other Factors
Intrinsic Vulnerability: B=Moderately vulnerable
Comments: Pinus albicaulis is at least moderately vulnerable. It is it a slow-growing species which takes a relatively long period to reach sexual maturity. In addition, it is completely dependant on Clark's nutcracker for dispersal and subsequent recruitment.

Finally, as discussed in the threats section, Pinus albicaulis has low levels of resistance to white pine blister rust.
Environmental Specificity: C=Moderate. Generalist or community with some key requirements scarce.
Comments: Moderate specificity. Pinus albicaulis occurs in specific mountain habitats both in the interior and the coast of southern BC. It occurs in nine different biogeoclimatic zones in BC, but 92% of the population occurs in only one of them: the Engelmann Spruce - Subalpine Fir zone (E. Campbell, pers comm. 2007). In the Coast Range, most of the P. albicaulis occurrences are in the dry to very dry regional climates and in the interior, most are in the mild subzone/variants.
Other Rank Considerations: Whitebark pine is a 'keystone' species of high-elevation ecosystems in western North America and its decline will have cascading impacts on ecosystem function and biological diversity (Tomback et al.2001). Whitebark pine strongly influences patterns of snow accumulation and snowmelt, and its continued decline may alter watershed hydrology affecting slope stability and the timing, levels, and quality of stream flow. Whitebark pine also moderates microenvironments and facilitates the recruitment and growth of other plants. It is also inexorably linked to Clark's nutcracker (Nucifraga columbiana), which has evolved to exploit the highly nutritious seed of this pine (Lanner, 1996). In addition, the seeds of whitebark pine are also an important source of dietary fat for other animals such as red squirrels (Tamiasciurus hudsonicus) and grizzly bears (Ursus arctos L.), which have increased reproductive success in years of abundant seed production (Mattson & Jonkel, 1990).
 
Information Gaps
Research Needs:
Inventory Needs:
 
Stewardship
Protection:
Management:
 
Version
Author: Penny, J.L. and E.M. Campbell
Date: March 31, 2013
 
References
Campbell, E.M. and A. Carroll. 2007. Climate-related changes in the vulnerability of whitebark pine to mountain pine beetle outbreaks in British Columbia. Nutcracker Notes 12: 13-15.
Campbell, E.M. and J. Antos. 2003. Postfire succession in Pinus albicaulis - Abies lasiocarpa forests of southern British Columbia. Can. J. Bot. 81: 383-397.
Campbell, E.M., and J. A. Antos. 2000. Distribution and severity of white pine blister rust and mountain pine beetle on whitebark pine in British Columbia. Can. J. For. Res. 30: 1051-1059.
Chourmouzis, C. A. D. Yanchuk, A. Hamann, P. Smets, and S.N. Aitken. 2009. Forest Tree Genetic Conservation Status Report 1 In Situ Conservation Status of All Indigenous British Columbia Species. TECHNICAL REPORT 053. Ministry of Forests and Range Forest Science Program.
COSEWIC. 2010c. COSEWIC assessment and status report on the Whitebark Pine Pinus albicaulis in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. x + 44 pp.(www.sararegistry.gc.ca/status/status_e.cfm).
Environment and Climate Change Canada. 2017k. Recovery Strategy for the Whitebark Pine (Pinus albicaulis) in Canada [Proposed]. Species at Risk Act Recovery Strategy Series. Environment and Climate Change Canada, Ottawa. viii + 54 pp.
Haeussler, S., A. Woods, K. White, E. Campbell and P. LePage. 2009. Do whitebark pine - lichen ecosystems of west central British Columbia display tipping point behaviour in response to cumulative stress? Bulkley Valley Research Centre Research Report, Smithers, BC. 23 p. Online. Accessed: http://bvcentre.ca/files/research_reports/09- 06WhitebarkPineReportOct29-09.pdf (3 May 2011).
Hamann, A., and T. Wang. 2006. Potential effects of climate change on ecosystem and tree species distribution in British Columbia. Ecology 87 (11) Pp 27732786.
Hoff, R., R.T. Bingham and G.I. McDonald. 1980. Relative blister rust resistance of white pines. Eur. J. For. Pathol. 10: 307-316.
Keane, R.E., and S.F. Arno. 1993. Rapid decline of whitebark pine in western Montana: evidence from 20-year remeasurements. West. J. Appl. For. 8: 44-47.
Lanner, R.M. 1996. Made for each other: a symbiosis of birds and pines. Oxford, New York.
Mattson D.J. and C. Jonkel. 1990. Stone pines and bears. Pages 29-31 in W. C. Schmidt and K. J. MacDonald, eds. Proceedings of a symposium on: Whitebark Pine Ecosystems: Ecology and Management of a High Mountain Resource. USDA For. Serv. Gen. Tech. Rep. INT-270.
Schrag, A.M., A. G. Bunn, and L. J. Graumlich. 2007. Influence of bioclimatic variables on tree-line conifer distribution in the Greater Yellowstone Ecosystem: implications for species of conservation concern. Journal of Biogeography. In press.
Smith, C.M., D. Langor, C. Myrholm, J. Weber, C. Gillies, and J. Stuart-Smith. 2013. Changes in blister rust infection and mortality in limber pine over time. Canadian Journal of Forest Research: (accepted for publication).
Tomback, D. and K. Kendall. 2001. Biodiversity losses: the downward spiral. Pages 254-266 in D. F. Tomback, S. F. Arno, and R. E. Keane, eds. Whitebark pine communities: ecology and restoration. Island Press. Washington, DC.
Warwell, M., G.E. Rehfeldt and N. Crookston. 2006. Modeling contemporary climate profiles of whitebark pine (Pinus albicaulis) and predicting responses to global warming. Proc. of the Conference on Whitebark pine: A Pacific Coast Perspective.
Wilson, B. Personal Communication. Researcher, Selkirk Geospatial Research Centre; instructor, Selkirk College, Castlegar, BC.
Zeglen, S. 2002. Whitebark pine and white pine blister rust in British Columbia, Canada. Canadian Journal of Forest Research 32: 1264-1274.
 

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Suggested Citation:

B.C. Conservation Data Centre. 2013. Conservation Status Report: Pinus albicaulis. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jan 17, 2026).