Can climate variability and landscape position predict white pine blister rust incidence, mortality due to the disease, and regeneration in whitebark pine?

Abstract

Invasive forest pathogens, like Cronartium ribicola (Fisch), the fungus that causes white pine blister rust, threaten native tree species. Federally listed whitebark pine (Pinus albicaulis Engelmann) is highly susceptible and faces extensive mortality due to this disease. Understanding infection conditions and disease incidence variability is crucial for management and restoration efforts. We surveyed whitebark pine stands in Glacier National Park, Montana, USA from 2020 to 2022, examining the impact of landform and climate on tree mortality, rust incidence, cone production, and regeneration. Our analysis revealed that tree diameter, elevation, and aspect significantly influenced mortality, rust incidence, and cone production, while climatic factors such as spring solar radiation, humidity, and late summer snowpack also played key roles. Regeneration was primarily affected by elevation, geographic location, and humidity. Although landform variables similarly predicted disease incidence in this and other studies, climatic drivers varied by region, emphasizing the need to consider region-specific landform and climate for effective management. Our study highlights the importance of protecting large trees, which harbor genetic diversity crucial for recovery and adaptation to disturbance and climate change.