Whitebark Pine

Rare Plant Profile – Whitebark Pine, Pinus albicaulis Engelmann [1]

Whitebark pine (Pinus albicaulis Engelmann) is a long-lived conifer tree species in the Pinaceae Family that often lives more than 500 years, but can live over 1000 years. Whitebark pine needles are in bundles of five and are 4-7 cm long. Mature trees can be 5-20 m tall, and may reach over 1 m in diameter at the base. Cones remain on the tree unless removed by animals [2]. Sizable crops of cones take 60-80 years to be produced.Whitebark pine occur in high elevations in montane and subalpine habitats often on ridgetops or exposed upper slopes, in soils that are coarse, rocky and shallow over bedrock [3]. This pine is located along the Coast Mountain Ranges in B.C. and along the Rocky Mountains in Alberta and B.C., and in both cases continue south of the border to the Southern States. In Alberta, whitebark pine is found from Jasper and Banff National Parks, at its northern extent, to the Canada-US border on the southern edge of Waterton Lakes National Park [4]. It is considered a keystone species because its seeds are an important food source for a number of animals, it provides slope stabilization, and it facilitates the establishment and growth of other plants in the harsh, upper subalpine environment [5]. It plays an important function in headwater streamflow control by helping regulate snowpack and runoff.

Whitebark pine is provincially ranked as Vulnerable, nationally ranked, with some level of uncertainty, as Imperiled to Vulnerable, and globally ranked, with some level of uncertainty, as Vulnerable to Apparently Secure [6]. This tree is listed as Endangered in Alberta under the Alberta Wildlife Act [7], and Endangered in Canada under the Species at Risk Act, due to the high risk of extirpation from the impending threat of disease [8]. Whitebark pine faces several threats including white pine blister rust (WPBR) (Cronartium ribicola), mountain pine beetle (Dendroctonus ponderosae), prolonged widespread fire suppression, and rapid global climate change [9]. However, WPBR is the most pervasive of the threats. Whitebark pine is not able to withstand the cumulative and rapid effects of threats, due in part to its life history traits such as the time to maturity, low dispersal rates, and its reliance on Clark’s Nutcracker for seed dispersal.

Currently Alberta is working on the long-term conservation of the whitebark pine through the provincial Recovery Plan, which addresses threats and identifies priority areas and actions for whitebark pine recovery [10]. One of the focuses of the recovery of whitebark pine lies in identifying trees that are potentially resistant to WPBR, which can then be used as seed sources for future recovery initiatives.

Figure 1. Whitebark pine (Lorna Allen)
Figure 2. Cones of whitebark pine (Jane Lancaster)
Figure 3 . Whitebark pine with white pine blister rust (Linda Kershaw)