Whitebark Pine ecology and management: synthesizing current understanding

Whitebark pine (Pinus albicaulis), an ecologically important tree species of high-elevation ecosystems of western North America, is declining across most of its range due to the combined effects of an invasive pathogen (blister rust; Cronartium ribicola) and a native insect (mountain pine beetle; Dendroctonus ponderosae), as well as climate-change-induced increases in wildfire frequency and severity. Concern over these threats to whitebark pine as well as successional replacement by shade-tolerant firs has led to its listing under both the US and Canadian Endangered Species Acts and an increase in research activities. In addition, management agencies have adopted coordinated, trans-boundary restoration strategies (e.g., Range-Wide Restoration Strategy for Whitebark Pine and the National Whitebark Pine Restoration Plan) that call for silvicultural treatments and prescribed burning, among other interventions. Despite a growing literature and widespread agreement on the need for conservation and restoration, there is little synthetic information on the species ecology, successional dynamics, and response to management interventions. In order to identify gaps in knowledge and improve restoration strategies for white bark pine, we conducted a literature review on the status of knowledge on the species in general. Specifically, we identified all publications listed on Web of Science and grey literature available on AGRICOLA (National Agricultural Library, USDA) from 1950 to 2018 using the search terms whitebark pine and “Pinus albicaulis”. We only reviewed articles that mentioned the species in the abstract or title, or studies in which whitebark pine ecosystems were a main focus. Although the number of published articles has been increasing over the last 30 years, most studies focused on biotic interactions (27%), pathogens and MPB outbreaks (39%), mortality (35%), and regeneration dynamics (25%). On the other hand, there was very little available information on the efficacy and effects of restoration and other management activities (less than 10% of all articles). There were also few articles published on the species life history, fire ecology and successional dynamics. Our findings indicate a significant gap in information required for effective conservation and restoration of whitebark pine. To improve capacity for successful management of whitebark pine, there is a need to invest in research that aligns with conservation needs