Pinus albicaulis - Engelm.
Whitebark Pine
Other Common Names: whitebark pine
Taxonomic Status: Accepted
Related ITIS Name(s): Pinus albicaulis Engelm. (TSN 183311)
French Common Names: pin ŕ écorce blanche
Unique Identifier: ELEMENT_GLOBAL.2.128475
Element Code: PGPIN04010
Informal Taxonomy: Plants, Vascular - Conifers and relatives
 
Kingdom Phylum Class Order Family Genus
Plantae Coniferophyta Pinopsida Pinales Pinaceae Pinus
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Pinus albicaulis
Conservation Status
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NatureServe Status

Global Status: G3G4
Global Status Last Reviewed: 26Aug2016
Global Status Last Changed: 02Oct2008
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G3 - Vulnerable
Reasons: A common tree where it occurs, it is limited to only upper subalpine forests of many western North American mountain ranges. It is, however, severly threatened in the majority of its range by introduced white pine blister rust (Cronartium ribicola), outbreaks of mountain pine beetle (Dendroctonus ponderosae), succession resulting from decades of fire suppression, climate change resulting in decreases in suitable habitat, and various synergies between these factors. Although a few areas such as the southern Sierra Nevada in California and the interior Great Basin ranges, as well as scattered stands in the rest of the range, still appear to contain large numbers of relatively healthy trees, it is expected that the blister rust will eventually become abundant in the vast majority of the range, causing significant tree mortality. Tree mortality rates exceeding 50% have already been documented in numerous parts of the range. A small percentage (1-5%) of trees appear naturally resistant to the blister rust, and restoration strategies hope to propagate these genotypes for use in restoration, although even rust-resistant trees will remain threatened by other factors. In addition, it has relatively low genetic variation and exists as a fragmentary species, making it more vulnerable than its range might indicate. This is a keystone species of high-elevation western ecosystems whose decline is expected to have cascading effects on ecosystem function and biodiversity.
Nation: United States
National Status: N3N4
Nation: Canada
National Status: N2N3 (04Feb2016)

U.S. & Canada State/Province Status
United States California (SNR), Idaho (S4), Montana (S2), Nevada (SNR), Oregon (S4), Washington (SNR), Wyoming (S3)
Canada Alberta (S2), British Columbia (S2S3)

Other Statuses

U.S. Endangered Species Act (USESA): C: Candidate (05Dec2014)
U.S. Fish & Wildlife Service Lead Region: R6 - Rocky Mountain
Canadian Species at Risk Act (SARA) Schedule 1/Annexe 1 Status: E (20Jun2012)
Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Endangered (25Apr2010)
Comments on COSEWIC: This long-lived, five-needled pine is restricted in Canada to high elevations in the mountains of British Columbia and Alberta. White Pine Blister Rust alone is projected to cause a decline of more than 50% over a 100 year time period. The effects of Mountain Pine Beetle, climate change, and fire exclusion will increase the decline rate further. Likely, none of the causes of decline can be reversed. The lack of potential for rescue effect, life history traits such as delayed age at maturity, low dispersal rate, and reliance on dispersal agents all contribute to placing this species at high risk of extirpation in Canada. Designated Endangered in April 2010.

NatureServe Global Conservation Status Factors

Range Extent Comments: A dominant tree in many upper subalpine forests of western North America; it is limited to subalpine and timberline zones from west-central British Columbia (55N) east to west-central Alberta and south to central Idaho, southwestern Wyoming, and southern California (36N) (Murray, 2005; Ward et al., 2006). Its distribution splits into 2 broad sections, 1 following the Coast and Cascade ranges and the Sierra Nevada, and the other following the northern Rocky Mountains. Scattered populations occur between the 2 sections in Great Basin regions of eastern Washington and Oregon and northern Nevada (Burns and Honkala, 1990; Fryer, 2002). Little (1971) mapped the range of this species, and a digitized representation of that map (USGS 1999) covers approximately 400,000 square km.

Number of Occurrences: 81 to >300
Number of Occurrences Comments: Although historical sources include Utah in the distribution, more recent workers have not found it to occur there (Flora of North America, 1993). It is absent from some of the wettest areas, such as the mountains of Vancouver Island; and in the Olympic Mountains, it is confined to peaks in the northeastern rain shadow zone and also occurs atop the highest peaks of the Klamath Mountains of northwestern California (Burns and Honkala, 1990). The Rocky Mountain distribution extends along the high ranges in eastern British Columbia and western Alberta, and southward at high elevations to the Wind River and Salt River Ranges in west-central Wyoming (Burns and Honkala, 1990). A small outlying population of whitebark pine is found atop the Sweetgrass Hills in north-central Montana 145 km (90 mi) east of the nearest stands in the Rocky Mountains across the Great Plains grassland (Thompson and Kuijt, 1976). The coastal and Rocky Mountain distributions lie only 100 km (62 mi) apart at their closest proximity (Bailey, 1975) and even this narrow gap is not absolute; small groves are found on a few isolated peaks in between in northeastern Washington. In addition to the main distribution, it grows in the Blue and Wallowa Mountains of northeastern Oregon and in several isolated ranges rising out of the sagebrush steppe in northeastern California, south-central Oregon, and northern Nevada (Burns and Honkala, 1990). Communities are found in four of Oregon's ecoregions: Blue Mountains, Klamath Mountains, Eastern Cascade Slopes and Foothills, and Cascades (Murray, 2005).

Population Size Comments: Measures of genetic diversity differed markedly among the studies and depended on the type of genetic marker used (isozyme or DNA) and the statistic reported. Using isozymes, Jorgensen and Hamrick (1997) found low expected heterozygosity both within populations (from 0.07 to 0.109 in Washington and Oregon) and within the species as a whole (0.102); reporting very low genetic diversity compared to other pines, including other stone pines, at both the population and the species level. In contrast, isozyme data in Krakowski et al. (2003) yielded expected heterozygosity of 0.257 in the species overall and 0.260 in one population from Washington. These measures fall midrange among reported values for pine species. Using chloroplast (cp)DNA, Richardson et al. (2002) found very high values for gene diversity, the haploid equivalent of expected heterozygosity; where gene diversity was 0.928 for the northern Cascades and 0.915 for southern Oregon. Estimates for genetic differentiation among populations were low to moderate in all studies from the region, and suggesting that most genetic variation in whitebark pine is found within populations. These measures of genetic differentiation are low compared to other pine species, but especially low for a species with a fragmented distribution (Ward et al., 2006). Significant levels of inbreeding were documented in whitebark pine (Jorgensen and Hamrick, 1997; Krakowski et al., 2003), which may increase the susceptibility of populations to blister rust. Evidence of slight genetic divergence between the eastern and western regions of whitebark pine's range was revealed using both isozymes (Jorgensen and Hamrick, 1997) and mitochondrial DNA (mtDNA) (Richardson et al. 2002).

Viability/Integrity Comments: It is abundant and vigorous on the dry, inland slope of the Coast and Cascade Ranges (Burns and Honkala, 1990). At high elevations where conditions are too harsh for other trees to survive, the enduring whitebark pine forms pure stands on sites that would otherwise be devoid of tree growth and is considered a keystone species (Murray, 2005).

Overall Threat Impact: Very high - high
Overall Threat Impact Comments: Introduced white pine blister rust, increases in mountain pine beetle, fire suppression (kills the trees, or leaves weakened survivors vulnerable to attack by native mountain pine beetles which tend to kill mature trees that are the best cone producers), development (a variety of road-building and development projects such as at Timberline Lodge, Crater Lake's Rim Drive, and several ski areas), climate change and associated successional replacement, and their synergistic effects threaten this species' survival, with the blister rust believed to be the most compelling threat throughout the range (Fryer, 2002; Murray, 2005; Murray and Rasmussen, 2000; Ward et al., 2006).

WHITE PINE BLISTER RUST: White pine blister rust, a fungal disease caused by the pathogen Cronartium ribicola, was inadvertently introduced to Vancouver, British Columbia in 1910. In most parts of whitebark pine's range today, the majority of surveyed stands are declining in condition as a result of blister rust infection. For example, blister rust infection was found in 96% (164 of 170) of surveyed stands in Washington and Oregon (Ward et al. 2006), 83% in Bob Marshall Wilderness Complex in Montana (Keane et al., 1994), "the vast majority" of stands in Alberta, and "all of the regions sampled" during the most recent British Columbia survey (Alberta Sustainable Resource Development and Alberta Conservation Association 2007). Throughout the species' range there are few stands that show no infection (Alberta Sustainable Resource Development and Alberta Conservation Association 2007).
In general, moist, humid conditions are believed to promote the spread of white pine blister rust and dry conditions to slow it; therefore increased global warming trends should favor the spread of the disease (see below). Stands that combine high elevation, dry conditions, and a fire regime of non-lethal underburns at long intervals are believed to be some of the healthiest remaining, avoiding the worst impacts of both blister rust and fire suppression; such stands occur mostly in the southern parts of the range in the Rocky Mountains (less than 10% of range) (Keane 1999). Nevertheless, environmental conditions at the extremes of whitebark pine's distribution - including cool temperatures, shorter growing seasons, and greater aridity - that were initially thought to provide some refuge from blister rust infection (e.g. USFWS 1994) are now known to only slow its spread. The epidemic is still spreading into and increasing within environments previously considered inhospitable, and the vast majority of the natural range is now believed to harbor the pathogen (Wars et al. 2006, Alberta Sustainable Resource Development and Alberta Conservation Association 2007).
The percentage of individual trees infected appears to vary widely throughout the range, with some areas having very high infection (> 90% per Alberta Sustainable Resource Development and Alberta Conservation Association 2007) and a few areas believed to have low impacts as yet. The highest infection levels (50-100%) are believed to occur in the northwestern U. S. and southwestern Canada in the northern Rockies and Cascades (Tomback 2002, Whitebark Pine Ecosystem Foundation 2006); Tomback (2002) also notes high infection in the intermountain ranges. Ward et al. (2006) state that "there is a high degree of localized variation in the prevalence of blister rust infection...hot spots of higher damage can occur...even in areas of moderate infection." In Oregon and Washington, the average percentage of infected living trees per stand (for stands that had infected treees) ranged from 11% to 95% (Ward et al. 2006). At two locations east of the Continental Divide in the northern Rocky Mountains, Montana, 35% of sampled trees were infected (Resler and Tomback 2008). At four biogeographically variable sites in the Greater Yellowstone Ecosystem, 85% sampled trees were infected (Tinker and Bockino 2007). In Alberta, approximately 60% of sampled trees were infected in the northern region, 16% were infected in the central region, and 73% were infected in the southern region (Alberta Sustainable Resource Development and Alberta Conservation Association 2007). In British Columbia, in 483 stands distributed over the major mountain ranges, forest district levels of infection ranged from 18% to 53% (average 34%) (Zeglen 2002 cited in Alberta Sustainable Resource Development and Alberta Conservation Association 2007). In contrast, in California, whitebark pine is not believed to be in serious decline in the Sierra or Warner Moutains; T. Keeler-Wolf (pers. comm. 2008) states that "despite the white pine blister rust problem and others [elsewhere in the range], there is still tons of [whitebark pine] in the Sierra and although some has died from disease it is still the most abundant subalpine conifer." A 2002 survey in Sequoia and Kings Canyon National Parks in the southern Sierra Nevada documented cankers on few to no trees (Duriscoe and Duriscoe 2002 cited in Whitebark Pine Ecosystem Foundation 2006). The interior Great Basin ranges also appear to be minimally impacted by blister rust at this time (Whitebark Pine Ecosystem Foundation 2006).
Within each stand, the percentage of dead trees (mortality) from blister rust alone, and from all causes combined, tends to be significantly less than the percentage of infected living trees. Nevertheless, some areas have already experienced substantial (>50%) mortality (Alberta Sustainable Resource Development and Alberta Conservation Association 2007). Furthermore, most mature trees infected with blister rust suffer loss of reproductive potential well before mortality occurs; thus many infected trees are no longer contributing to the maintenance of the population even though they remain alive (Alberta Sustainable Resource Development and Alberta Conservation Association 2007). In Oregon and Washington, the average mortality per stand from all causes ranged from 2% to 41% (Ward et al. 2006). In a study that measured 17 permanent plots in western Montana at two intervals separated by 20 years, there was an average mortality rate of 42% over the 20 year period (Keane and Arno 1993 cited in Alberta Sustainable Resource Development and Alberta Conservation Association 2007). At four biogeographically variable sites in the Greater Yellowstone Ecosystem, 52% of the whitebark pine sampled were dead from multiple causes (Tinker and Bockino 2007). In southern Alberta, the average mortality in a recent survey was 61%; at eight permanent plots in this region, the mortality rate increased from 26% to 61% between 1996 and 2003. However, mortality is lower in central and northern Alberta (Alberta Sustainable Resource Development and Alberta Conservation Association 2007). In British Columbia, in 483 stands distributed over the major mountain ranges, the range of mortality caused by blister rust was estimatd to be between 4% and 22% (average 10%) and the range of mortality from all causes was estimatd to be between 6% and 31% (average 19%) (Zeglen 2002 cited in Alberta Sustainable Resource Development and Alberta Conservation Association 2007).
Although projections of the future should technically not be considered in evaluating short term trend, it is worth mentioning that several studies have found these to be grim. In Mt. Rainier National Park, Washington, without any management intervention, 150-175 year simulations predict a 65-94% chance of whitebark pine extinction in the Park (Cottone 2001 cited in Ward et al. 2006, Ettl and Cottone 2004 cited in Alberta Sustainable Resource Development and Alberta Conservation Association 2007). In Crater Lake National Park, an overall decline of 0.4 percent per year for mature trees is predicted, which would lead to a 20 percent reduction in the Park within 50 years (Murray and Rasmussen 2000, 2003 cited in Ward et al. 2006). Murray (2005) predicts 95-99% mortality in Oregon populations due to blister rust.
However, there is some hope for the persistence and recovery of this species since naturally resistant trees have been found at many locations. Natural resistence to white pine blister rust infection is believed to exist in approximately 1-5% of the total whitebark pine population (Keane 1999), although resistant trees are still susceptible to other causes of mortality such as mountain pine beetle attack. Some researchers familiar with the species do expect it to persist, although noting that the structure of stands and the landscape pattern of their distribution may be different than the historical condition.

MOUNTAIN PINE BEETLE (Dendroctonus ponderosae): Mountain pine beetle is native to western North America and appears to have periods of higher and lower population density over time. For example, between 1909 and 1940 and again from the 1970s to the 1980s, outbreaks of mountain pine beetle killed whitebark pine throughout the U.S. Rocky Mountains (Whitebark Pine Ecosystem Foundation 2006). Drought and warmer temperatures in recent years have allowed unprecedented increases in beetle abundance and distribution. The first decade of the 20th century has seen further outbreaks within much of the U.S. range as well as attacks in British Columbia and Alberta of unprecedented scope and severity.
Studies in various parts of whitebark pine's range suggest the severity of impacts. 2006 aerial surveys indicated large-scale outbreaks of beetles in whitebark pine in northern Idaho, west-central and southwestern Montana, and the Greater Yellowstone Ecosystem (Gibson 2006 cited in Whitebark Pine Ecosystem Foundation 2006). In the Greater Yellowstone Ecosystem, the current mountain pine beetle outbreak is unprecedented in scope and severity: more than 700,000 whitebark pines were killed by beetles in 2004 (Whitebark Pine Ecosystem Foundation 2006), and at four biogeographically variable sample sites, 70% of whitebark pine were attacked by the beetle (Tinker and Bockino 2007). Observations in 2005 suggested that mountain pine beetle occurrence in whitebark pine is increasing in Oregon and Washington locations as well, such as Okanogan and Wenatchee National Forests and Crater Lake National Park (Ward et al. 2006). While whitebark pine losses due to mountain pine beetle in British Columbia and Alberta were relatively minor prior to the 1980s, warming climates have led to an expansion of beetle outbreaks into higher elevation forest containing whitebark pine (Campbell and Antos 2000, Campbell and Carroll 2007 cited in BC CDC 2008). In the 1980s outbreak, the beetle is believed to have affected a large decrease (30-40%) in mature whitebark pine canopy cover in southern Alberta. In British Columbia, 2007 aerial surveys indicated widespread beetle infestations and tree death, with about 7% of BC forests containing whitebark pine infested (Campbell and Carroll 2007 cited in BC CDC 2008) and impacts expanding into Alberta. This epidemic is projected to continue over the next few years (BC CDC 2008).
As for white pine blister rust, a small percentage of whitebark pine trees (3-5%) appear able to resist mountain pine beetle attack (BC CDC 2008).

FIRE SUPPRESSION AND SUCCESSIONAL REPLACEMENT: Prior to about 1930, the replacement of whitebark pine by later successional species such as spruce and fir was usually interrupted by naturally occurring fires. However, decades of fire suppression have allowed spruce and fir to become dominant in many forests that were historically dominated by whitebark pine. This threat appears to be particularly significant in the northern Rocky Mountains of the United States and the intermountain region (Whitebark Pine Ecosystem Foundation 2006), and in moister areas at lower elevations (Ward et al. 2006). Whitebark pine survives low severity fires better than its competitors because it has thicker bark, thinner crowns, and deeper roots. It is also well-adapted to recolonizing burned areas, as its seed disperser, Clark's nutcracker, appears to prefer open sites for seed caching (Keane 1999). Prescribed burn to control blister rust often results in reinfected trees returning in greater numbers that regenerate more slowly than non-infected trees (Tomback et al., 1995).

CLIMATE CHANGE: Major reductions in habitat suitable for this subalpine species are expected as the climate warms (BC CDC 2008). Modeling mostly predicts a decline in whitebark pine due to global increases in temperature and more frequent summer droughts (Mattson et al., 2001; McCaughey and Tomback, 2001). Climate modeling for Yellowstone National Park predicts that independent of other agents of decline such as blister rust, whitebark pine is the most at-risk conifer in the Park due to drying conditions in high-elevation habitats (Bartlein et al., 1997). However, impact of climate change on whitebark pine is inconclusive: Keane et al. (1996) and others predict expansion of whitebark pine in Glacier National Park due to more frequent fire return intervals resulting from global warming. Increased global temperature makes the species more vulnerable to fungus such as blister rust (Murray, 2005).

SYNERGIES: Numerous studies have found that whitebark pine trees stressed by blister rust are more susceptible to attack by mountain pine beetle. Mortality from the combination of blister rust and mountain pine beetle has apparently exceeded 50% in areas including Glacier National Park, northwestern Montana, north-central Idaho, and northern Washington, and mortality is increasing rapidly in the Cascades and Sierra Nevada Range (Whitebark Pine Ecosystem Foundation 2006). Furthermore, the significant threat from both white pine blister rust and mountain pine beetle threatens the success of restoration strategies based on cultivating tree resistant to either threat alone (Whitebark Pine Ecosystem Foundation 2006). In addition, the tendency of both of these agents to kill mature, reproductive trees accelerates successional replacement processes resulting from fire suppression; and fire suppression itself is believed to have an inhibitory effect on whitebark pine's recovery from major beetle outbreaks (Keane 1999). Finally, climate change interacts significantly with the mountain pine beetle threat, as warmer temperatures increase he proportion of whitebark pine's range vulnerable to beetle attack (BC CDC 2008). Warmer temperatures also appear to permit the beetle to complete its life cycle more quickly (i.e. in one year) and to make summer dispersal flights more dependably (Alberta Sustainable Resource Development and Alberta Conservation Association 2007). Logging has also been noted as a threat in British Columbia; while it is not a significant threat on its own, since it occurs in healthy stands it reduces the number of intact stands as yet minimally affected by other threats, which may be important for future survival (E. Campbell, pers. comm. 2007 cited in BC CDC 2008).

Short-term Trend: Decline of >50%
Short-term Trend Comments: Whitebark pine is declining at an unprecedented rate. In the Sundance Burn (Selkirk Range) or northern Idaho, Tomback et al. (1995) observed 29% of regeneration trees following a prescribed burn were infected once again with blister rust. Keane et al. (1994) noted 22% of landscape in Bob Marshall Wilderness Complex (Montana) with high mortality, and 39% with moderate mortality, due to blister rust. Keane et al. (1996) and others estimated a 45% decline in whitebark pine cover types in the Columbia River Basin and the Bob Marshall Wilderness Complex of Montana. Ironically, whitebark pine decline is greatest on seral sites, where its productivity was historically best. The area occupied by seral whitebark pine has plummeted 98% (Keane et al., 1996; Fryer, 2002). Agents causing major whitebark pine mortality include white pine blister rust, successional replacement, bark beetles, fire, root diseases, and weather. Generation time is long; trees generally start producing cones when 25-30 years old, start producing sizable cone crops when 60-80 years old, and can live to be over 500 years old (Alberta Sustainable Resource Development and Alberta Conservation Association 2007). In Oregon, Murray (2005) anticipates 95-99% mortality of trees infected with blister rust. In Oregon's Crater Lake National Park, blister rust infects up to 20% of whitebark pine and Murray and Rasmussen (2000) predict 46% decline by 2050. During the past several years, mountain pine beetle outbreaks have erupted leading to noticeable loss of whitebark pine in the southern Cascades (Murray, 2005). Thus trends should be considered over a 100 year time frame. Introduced white pine blister rust, increases in mountain pine beetle, fire suppression, climate change, and their synergistic effects are causing significant ongoing declines in this species; see Threats for details.

Long-term Trend: Decline of 50-90%
Long-term Trend Comments: See Threats for details

Intrinsic Vulnerability Comments: Staff at Crater Lake National Park are also investigating forces affecting the survival of whitebark pine (Murray, 2005). This species grows slowly and takes considerable time to reach sexual maturity: trees start producing cones when 25-30 years old and do not produce sizable cone crops until 60-80 years old (Alberta Sustainable Resource Development and Alberta Conservation Association 2007). It also has a high degree of dependence on one bird species, Clark's nutcracker, for dispersal and recruitment (BC CDC 2008). Whitebark pine appears to be the only North American pine (Pinaceae) with a seed bank. Due to seed caching by Clark's nutcrackers and delayed seed germination, whitebark pine may show good seedling establishment even if the previous year's cone crop was poor. Studies conducted after the 1988 fires on the Gallatin National Forest and Yellowstone National Park found that germination rates of natural regeneration were greatest 2 years after good cone crops (Fryer, 2002). Whitebark pine seedlings are generally considered hardy after their 1st few weeks of life (Tomback et al., 2001; Arno and Raymond, 1990). Measures of genetic diversity differed markedly among the studies and depended on the type of genetic marker used (isozyme or DNA) and the statistic reported. Using isozymes, Jorgensen and Hamrick (1997) found low expected heterozygosity both within populations (from 0.07 to 0.109 in Washington and Oregon) and within the species as a whole (0.102); reporting very low genetic diversity compared to other pines, including other stone pines, at both the population and the species level. In contrast, isozyme data in Krakowski et al. (2003) yielded expected heterozygosity of 0.257 in the species overall and 0.260 in one population from Washington. These measures fall midrange among reported values for pine species. Using chloroplast (cp)DNA, Richardson et al. (2002) found very high values for gene diversity, the haploid equivalent of expected heterozygosity; where gene diversity was 0.928 for the northern Cascades and 0.915 for southern Oregon. Estimates for genetic differentiation among populations were low to moderate in all studies from the region, and suggesting that most genetic variation in whitebark pine is found within populations. These measures of genetic differentiation are low compared to other pine species, but especially low for a species with a fragmented distribution (Ward et al., 2006). Significant levels of inbreeding were documented in whitebark pine (Jorgensen and Hamrick, 1997; Krakowski et al., 2003), which may increase the susceptibility of populations to blister rust. Evidence of slight genetic divergence between the eastern and western regions of whitebark pine's range was revealed using both isozymes (Jorgensen and Hamrick, 1997) and mitochondrial DNA (mtDNA) (Richardson et al. 2002).

Environmental Specificity: Narrow. Specialist or community with key requirements common.
Environmental Specificity Comments: Whitebark pine survivorship is generally considered best on burns (Fryer, 2002), however, given open conditions and mineral soil, seedlings may show good survivorship on a variety of sites. Two strategies allow whitebark pine to survive in fire-prone ecosystems: survival of large and refugia trees, and postfire seedling establishment facilitated by Clark's nutcrackers. Mature whitebark pine survive low-severity surface fire. Moderate-severity surface fire kills the majority of mature trees. Severe surface and crown fires kill even the largest whitebark pine (Keane and Arno, 1993; Fryer, 2002). Plant life at timberline is challenged by poorly developed soils, heavy snowfall, a short growing season, ice storms, and ferocious winds; and several physical traits permit whitebark pine to endure a harsh environment - flexible branchlets shed snow, stout stems, and well anchored root systems (Murray, 2005). Although well-adapted to surviving at timberline, whitebark pine is not a strong competitor with other trees because of its relative shade intolerance and slow growth (Murray, 2005).

Other NatureServe Conservation Status Information

Distribution
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Global Range: A dominant tree in many upper subalpine forests of western North America; it is limited to subalpine and timberline zones from west-central British Columbia (55N) east to west-central Alberta and south to central Idaho, southwestern Wyoming, and southern California (36N) (Murray, 2005; Ward et al., 2006). Its distribution splits into 2 broad sections, 1 following the Coast and Cascade ranges and the Sierra Nevada, and the other following the northern Rocky Mountains. Scattered populations occur between the 2 sections in Great Basin regions of eastern Washington and Oregon and northern Nevada (Burns and Honkala, 1990; Fryer, 2002). Little (1971) mapped the range of this species, and a digitized representation of that map (USGS 1999) covers approximately 400,000 square km.

U.S. States and Canadian Provinces
Color legend for Distribution Map

U.S. & Canada State/Province Distribution
United States CA, ID, MT, NV, OR, WA, WY
Canada AB, BC

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
MT Powell (30077)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
17 Blackfoot (17010203)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Reproduction Comments: Whitebark pine has large, wingless, nutrient-rich seeds that remain in the indehiscent cone after maturity. It is not adapted for wind dissemination and is almost entirely dependent on Clark's nutcracker (Nucifraga columbiana) for successful dispersal and reproduction (Flora of North America, 1993; Lanner, 1982; Burns and Honkala, 1990; Murray, 2005). Nutcrackers feed almost exclusively on whitebark pine seeds when they are available and store the seeds for year-round use. With a full pouch of seeds, nutcrackers fly to a suitable site and cache clusters of up to 15 seeds 2-3 cm below the soil surface. The birds have been observed traveling anywhere from several hundred meters to over 10 km to cache seeds (Alberta Sustainable Resource Development and Alberta Conservation Association 2007). Various mammals (red squirrel, black bear, grizzly bear, chipmunk, golden-mantled ground squirrel, deer mice) also transport and cache seeds (Hutchins and Lanner, 1982; Tomback, 1978), but not nearly to the extent of the Clark's nutcracker. Trees do not reach full cone production until 60 to 100 years of age on most sites (Lewis, 1971; McCaughey and Tomback, 2001). Peak cone production extends for another 250 years, then gradually declines.
Terrestrial Habitat(s): Forest - Conifer, Forest/Woodland, Woodland - Conifer
Habitat Comments: Within montane forests and on thin, rocky, cold soils at or near timberline. 1300 - 3700 m (Flora of North America 1993). In moist mountain ranges, whitebark pine is most abundant on warm, dry exposures; but in semiarid ranges, it becomes prevalent on cool exposures and moist sites (Burns and Honkala, 1990). Although its role in the plant community is changing, whitebark pine historically dominated many of the upper subalpine plant communities of the western United States and was a major component of subalpine forests in the northern Rocky Mountains, the northern Cascades, the Blue Mountains, and the Sierra Nevada. It comprises 10 to 15% of total forest cover in the northern Rocky Mountains (Fryer, 2002). It was a minor component of subalpine forests in British Columbia and Alberta, and showed scattered occurrence on the Olympic Peninsula, the southern Cascades and other ranges of southern Oregon and upper northern California, and in northern Nevada (Burns and Honkala, 1990). At high elevations, krummholz whitebark pine communities merge into alpine vegetation. At mid-elevation, whitebark pine communities merge into mixed-conifer forests (Burns and Honkala, 1990). Most whitebark pine stands grow on weakly developed (immature) soils. Many of the sites were covered by extensive mountain glaciers during the Pleistocene and have been released from glacial ice for less than 12,000 years (62); and chemical weathering is retarded by the short, cool, summer season. Throughout its distribution, whitebark pine is often found on soils lacking fine material (Burns and Honkala, 1990).
Economic Attributes
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Economically Important Genus: Y
Management Summary Not yet assessed
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Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 30Nov2010
NatureServe Conservation Status Factors Author: Cordeiro, J. (2010); Morse, Larry E. (2000), rev. K. Gravuer (2008)
Element Ecology & Life History Edition Date: 22Nov2010
Element Ecology & Life History Author(s): Cordeiro, J.

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
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  • Alberta Sustainable Resource Development and Alberta Conservation Association. 2007. Status of the Whitebark Pine (Pinus albicaulis) in Alberta. Alberta Sustainable Resource Development, Wildlife Status Report No. 63, Edmonton, AB. 22 pp. Online. Available: http://www.srd.gov.ab.ca/fishwildlife/status/pdf/Whitebark_Pine_Status_Report63_WEB.pdf (Accessed 2008)

  • Andersen, M.D. and B. Heidel. 2011. HUC-based species range maps. Prepared by Wyoming Natural Diversity Database for use in the pilot WISDOM application operational from inception to yet-to-be-determined date of update of tool.

  • B.C. Conservation Data Centre. 2008 . Conservation Status Report: Pinus albicaulis. B.C. Ministry of Environment. Available: http://a100.gov.bc.ca/pub/eswp/ (Accessed September 2008).

  • Bailey, D.K. 1975. Pinus albicaulis. Curtis's Botanical Magazine 180(111):140-147.

  • Bartlein, P.J., C. Whitlock, and S.L. Shafer. 1997. Future climate in the Yellowstone National Park region and its potential impact on vegetation. Conservation Biology 11(3):782-792.

  • Billings, W.D. 1951. Vegetational zonation in the Great Basin of western North America. Union of International Science: Biological Series B. 9:101-122.

  • Bruederle, L.P., D.F. Tomback, K.K. Kelly, and R.C. Hardwick. 1998. Population genetic structure in a bird-dispersed pine, Pinus albicaulis (Pinaceae). Canadian Journal of Botany 7:83-90.

  • Bruederle, L.P., D.L. Roger, K.V. Krutovskii, and D.V. Politov. 2001. Population genetics and evolutionary implications. Pages 137-157 in D.F. Tomback, S.F. Arno, and R.E. Keane (eds.) Whitebark Pine Communities: Ecology and Restoration. Island Press: Washington, DC: Island Press.

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