In 2003–2004, we examined 8031 whitebark pine ( Pinus albicaulis Engelm.) trees and 3812 seedling-establishment sites in 170 plots for mortality and incidence of white pine blister rust ( Cronartium ribicola A. Dietr.). We found blister rust in all but four plots (98%), and 57% of all trees assessed for blister rust were either already dead or showed signs of blister rust infection. Mean percentage of trees infected was highest in the southern Canada – United States border area (∼73%), decreasing to a low in the northern region of Banff National Park, Alberta (∼16%), and then rising (∼60%) in the northern end of the study area in Jasper National Park, Alberta. Stands with higher infection, mortality, and canopy kill of trees and higher presence of rust on seedlings tended to be located on the western side of the Continental Divide. In the eight stands in Waterton Lakes National Park, Alberta, that had been previously assessed in 1996, infection levels increased from 43% to 71%, and mortality increased from 26% to 61%, whereas no change was apparent in Glacier National Park, Montana, stands. The impacts of high mortality and infection levels, high crown kill, and reduced regeneration potential, suggest that the long-term persistence of whitebark pine in the southern part of the study area is in jeopardy.

This report has been reviewed, revised, and edited prior to publication.It is an SRD/ACA working document that will be revised and updated periodically. that occur in the province. Such designations are determined from extensive consultations with professional and amateur biologists, and from a variety of readily available sources of population data. A key objective of these reviews is to identify species that may be considered for more detailed status determinations.The Alberta Wildlife Status Report Series is an extension of the general status exercise, and provides comprehensive current summaries of the biological status of selected wildlife species in Alberta. Priority is given to species that are At Risk or May Be At Risk in the province, that are of uncertain status ( Undetermined ), or that are considered to be at risk at a national level by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).Reports in this series are published and distributed by the Alberta Conservation Association and the Fish and Wildlife Division of Alberta Sustainable Resource Development. They are intended to provide detailed and up-to-date information that will be useful to resource professionals for managing populations of species and their habitats in the province. The reports are also designed to provide current information that will assist Alberta's Endangered Species Conservation Committee in identifying species that may be formally designated as Endangered or Threatened under Alberta's Wildlife Act. To achieve these goals, the reports have been authored and/or reviewed by individuals with unique local expertise in the biology and management of each species.iii EXECUTIVE SUMMARY Whitebark pine ( Pinus albicaulis ) is found in high elevation forests in the mountainous regions of western North America. This hardy tree is a "keystone" species, as its seeds provide an important food source for a number of animals including squirrels, bears and, in particular, Clark's nutcracker (Nucifraga Columbiana). In Alberta, the species is found in isolated populations in the Rocky Mountains from Willmore Wilderness Park south to the Canada-U.S. border. However, exact numbers of individuals are difficult to estimate because of limited stand inventory throughout its provincial distribution.There are four main human-caused threats to whitebark pine throughout its range: 1) white pine blister rust (Cronartium ribicola ), an introduced fungus species; 2) increased presence of mountain pine beetle ( Dendroctonus ponderosae); 3) prolonged widespread fire suppression; and 4) rapid global climate change. In Alberta, the greatest threat is white pine blister rust. The vast majority of whitebark pine stands in Alberta are infected with this introduced fungus, which has already caused significant mortality in many stands, with the greatest effects evident in southern Alberta.A number of initiatives is needed for effective conservation and restoration of Alberta whitebark pine. Such initiatives include a detailed inventory of the speci...

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