E-Flora BC: Electronic Atlas of the Flora of British Columbia

Pinus albicaulis Engelm.
whitebark pine
Pinaceae (Pine family)

Introduction to Vascular Plants

© Curtis Bjork  Email the photographer   (Photo ID #15849)

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Distribution of Pinus albicaulis
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Introduction

Whitebark Pine is an evergreen, coniferous tree species of western North America, where it is found seven US states (CA, ID, MT, NV, OR, WA, WY) and two Canadian provinces (AB, BC). In British Columbia, it is frequent in southern BC east of Coast-Cascade Mountains and is rare northward to central and northeastern BC. It is found on mesic to dry slopes in the subalpine to alpine zones, and is considered a keystone species. Whitebark pine is in the white pine group, with 5 bluish, stiff needles per bundle that are clustered towards the ends of the branches. Bark is smooth and chalky-white on younger trees. This species has a variable shape and may be a small dwarfed tree or shrubby and sprawling (Douglas et al. 1998). Freshly cut wood is sweet scented.

Whitebark pine is an important food source for many birds and small mammals, and particularly for Clark's Nutcracker, which plays an important role in seed dispersal in this species. Clark's Nutcrackers cache seeds in the soil and use the caches when food is limited. Cache sites are usually good for seed germination, and can result in a clumped distribution of this species. Whitebark pine is threatened by White Pine Blister Rust, which was introduced from Europe, and which causes significant die-off. It is also threatened by Mountain Pine Beetle in western North America.

Flora North America provides a detailed description of this species.

More details on this species are given in the Gymnosperm Database.

Detailed information on the ecology and distribution of this species is given by Stephen F. Arno and Raymond J. Hoff in Sylvics of North America.

Species Information

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General:
Often contorted and dwarfed, 5-10 m tall, or a shrubby sprawling timberline tree, but also straight and up to 20 m; bark thin with light-whitish scales; young twigs hairy.
Leaves:
Needles in bunches of five, clustered towards ends of branches, (3) 4-7 cm long; yellow green.
Cones:
Seed cones egg-shaped, deep red to purple, (3.5) 5-8 cm long; scales remain closed and shed the seeds slowly, rarely falling from tree intact; pollen cones red.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

Flower Colour:
Yellow
Blooming Period:
Mid Summer
Fruit/Seed characteristics:
Colour: Brown
Present from Summer to Fall
Source:  The USDA

Habitat / Range

Mesic to dry slopes in the subalpine to alpine zones; frequent in S BC in and E of Coast-Cascade Mountains, rare northward to C and NE BC; E to SW AB and S to CA, NV and WY.

Source: The Illustrated Flora of British Columbia

Additional Notes

Whitebark pine belongs to the pine family, subsection Cembra (the stone pines), which are typified by their large, wingless seeds. These large seeds provide a food source for bears prior to hibernation through excavation of red squirrel caches. Whitebark pine is also tied to the ecology of Clark's Nutcracker in BC: "Whitebark pine, like other stone pines, has co-evolved with nutcrackers. The nutcrackers rely on stone pine seeds as their principal food source "for at least 9 months of the year and for raising the young. In addition to special adaptations on gathering, transporting, caching, and finding again the hoarded seeds, the whole annual cycle of the nutcracker's life (time of breeding and moulting), its mating system, and its habitat use are adjusted to the use of pine seeds" (Tomback et al. 1990)." (The Gymnosperm Database 2011).

Ecology

Ecological Framework for Pinus albicaulis

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class

Minimum

Average

Maximum

Elevation (metres) 253 1885 2649
Slope Gradient (%) 0 39 270
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
0 194 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
0 2 8
Modal Nutrient Regime
Class
B
Number of field plots
 species was recorded in:
1616
Modal BEC Zone Class
ESSF
All BEC Zones (# of stations/zone) species was recorded in: AT(133), BAFA(20), CWH(1), ESSF(1209), ICH(15), IDF(10), IMA(18), MH(6), MS(99), PP(1), SBS(4)

Ecological Indicator Information

A shade-intolerant, subalpine, Western North American evergreen conifer distributed more in the Pacific than the Cordilleran region. Occurs in continental alpine tundra and subalpine boreal climates on moderately dry to fresh, nitrogen-medium soils; its occurrence increases with increasing continentality and decreases with increasing latitude. Common in parkland forests on water-shedding sites which are free of snow early in the year. Often grows with Engelmann spruce and subalpine fir in the coast-interior ecotone. Characteristic of continental subalpine forests.

SourceIndicator Plants of Coastal British Columbia (Information applies to coastal locations only)

Climate

The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is alpine tundra & boreal.

Taxonomic and Nomenclatural Links

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General References