RustMapper: White Pine Blister Rust Risk Across High Elevation Forests in the Western United States

Area of Science:

• Ecology
• Forest Pathology
• Climate Science

Background:

• White pine blister rust (WPBR) poses a significant threat to North American forests, particularly high-elevation five-needle pine species (High-5).
• Understanding the environmental drivers of WPBR is crucial for effective forest management and conservation strategies.

Purpose of the Study:

• To estimate White Pine Blister Rust (WPBR) risk across the western U.S. for high-elevation five-needle pine species (High-5).
• To develop an adaptive management tool, RustMapper, to predict WPBR occurrence based on environmental variables.

Main Methods:

• Aggregated data from over 80 studies conducted between 1995-2024 in the western U.S.
• Utilized environmental factors including stream density, topography, hardiness zone, precipitation, air temperature, vapor pressure deficit, and relative humidity to model WPBR risk.
• Estimated WPBR risk (probability of disease presence) for High-5 species from 1980-2023.

Main Results:

• WPBR risk is strongly influenced by moisture (increasing risk) and temperature (decreasing risk).
• Suitable conditions for WPBR were identified in both invaded and uninvaded regions across the High-5 range.
• Mean WPBR risk was substantially higher in the northern parts of the High-5 range (~0.6) compared to the southern parts (~0.15).

Conclusions:

• Findings suggest cautious optimism for disease mitigation in established WPBR regions.
• Urgent, proactive management is recommended for areas with currently low WPBR occurrence but suitable conditions.
• The RustMapper tool provides valuable insights for managing WPBR in vulnerable pine ecosystems.