Whitebark pine


Whitebark pine above Castlegar, BC

As the only native North American stone pine, the whitebark pine (Pinus albicaulis) is currently at risk from white pine blister rust, mountain pine beetle, fire exclusion and rapid climate change. This species is currently listed as endangered by COSEWIC and is Blue Listed by the BC Provincial Government with little probability of rescue; life history traits (primarily delayed age at maturity, low dispersal rate and reliance of dispersal agents) do not allow for a quick and foreseeable recovery.

Map

Biodiversity Interactive Map - whitebark pine Habitat Suitability

Range

Whitebark pine is found in the high-elevation terrain of Canada and the USA, extending from areas in Wyoming and California, to approximately 200 km north of Ft. Saint James in the Coast Mountains and 150 km north of Jasper in the Rocky Mountains. Over 50 percent (190 067 km2) of whitebark pine?s global range is contained within Canadian borders.

Habitat

Whitebark pine is typically a high elevation species, preferring timberline elevations that vary latitudinally from 1950 to 2250 metres at the Canada-USA border and 1000 to 1600 metres in north-central British Columbia. whitebark pine is most prevalent on dry, southerly aspects with shallow rocky soils and well to rapid drainage. Due to these preferences habitat for this species is naturally discontinuous, especially between mountain ranges.

This species is relatively shade intolerant and is an early seral species in closed mixed stands. In older forests, most whitebark pine will be overtopped by other conifers, such as Engelmann Spruce (Picea engelmannii), Subalpine Fir (Abies lasiocarpa) or Mountain Hemlock (Tsuga mertensiana). In more open timberline locations, whitebark will occasionally occur in pure or nearly pure climax stands that exhibit continuous recruitment. However, establishment and regeneration typically arise after heavy disturbance?such as avalanches, glacial retreat and fires.

Biology

Whitebark pine is a Keystone species (integral to the continuation of many other species in an ecosystem), and as such would cause serious repercussions if it becomes extinct or even seriously depleted. whitebark pine is linked to other species primarily through its seeds—an important food source for a number of species including squirrels, bears and the Clark's Nutcracker. However, the tree species is also noted for its facilitation of a more rapid return to forested landscapes following disturbances.

The Clark?s Nutcracker and the whitebark pine are very closely tied, with the pine providing a primary food source when available and the nutcracker being the almost exclusive method of distribution of the whitebark pine seeds.

Whitebark pine is a long-lived species, typically attaining an age of over 500 years with occurrences exceeding 1000 years. It has a long generation cycle, around 60 years, with a tree not reaching sexual maturity until about 30-50 years and generally 60-80 for cone crops. Cone production peaks at about 250 years but can continue well past this age.

Seed germination is typically delayed after dispersal for a year or more. However, the majority of seeds tend to germinate within three years. Germination from the soil "seed bank", which is unusual for a pine, appears to occur when moisture conditions are most favourable.

Listing and Date

Listing Date
B.C. List Blue
COSEWIC Endangered April 2010
SARA

Threats to Species

  • White Pine Blister Rust (Cronartium ribicola) ? originating in Eurasia, accidentally introduced in the early 20th century. It affects all five-needled pines of North America, with only a few stands of whitebark pine showing no infection and over 90% with infection (50% mortality). It attacks the needles initially, quickly spreading through the vascular bundle and into the phloem. Cankers form two to four years following infection and rupture the bark allowing secondary pathogens to infiltrate. Vascular tissue loss, secondary infections and animal damage are the primary causes of mortality.
  • Mountain Pine Beetle (MPB) ? Due to the stress of Blister Rust infection, warmer winter temperatures and an increase in beetle density, whitebark pine is more susceptible to infection and mortality from MPB.
  • Fire Exclusion ? Fire prevention and suppression has removed the primary disturbance that permits the regeneration of whitebark pine in lower, older subalpine closed forests.
  • Climate Change ? Altered precipitation and temperature regimes may enable competing vegetation to exclude whitebark pine from much its current elevation range and enable lower elevation pathogens access to previously unobtainable territory.

Select Reports

For more information on this species, visit:
The Species at Risk Public Registry and/or, The BC Species and Ecosystem Explorer where you should enter "whitebark pine" in the species Name field.

 

 

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