Seeding of whitebark pine (Pinus albicaulis) in western north American subalpine forests: Development and application

The rapid decline of whitebark pine (Pinus albicaulis Engelm.), a keystone species of upper subalpine and treeline elevational zones across many of the higher mountains of the western United States and Canada, has prompted the development of restoration strategies and practical restoration applications. Whitebark pine has been federally listed as ‘threatened’ in the United States, which elevates the restoration imperative. Seeding potentially provides a low-cost means of establishing the species in remote areas with limited access and/or land use constraints, but this restoration tool still lacks sufficient advancement to ensure operational success. We present an overview of whitebark pine ecology, outline the factors leading to its decline, summarize ongoing conservation efforts and restoration strategies, and review the available literature on seeding whitebark pine to identify barriers that challenge successful operationalization. Informing and advancing land management for conservation of whitebark pine will require refining seeding protocols by monitoring and reporting on trials to mitigate the main barriers to this application. Additional research is required to reduce seed pilferage by rodents, improve sowing techniques, identify favorable sowing microsites for improved seeding outcomes, and develop a reliable supply chain for seed resistant to introduced disease.