A risk assessment of climate change and the impact of forest diseases on forest ecosystems in the Western United States and Canada

This risk assessment projects the effects of eight forest diseases under two climate-change scenarios (warmer and drier, warmer and wetter). Examples are used to describe how various types of forest diseases may respond to environmental changes. Forest diseases discussed in this report include foliar diseases, Phytophthora diseases, stem rusts, canker diseases, dwarf mistletoes, root diseases, and yellow-cedar decline. The likelihood and consequences of increased damage to forests from each disease as a result of climate change are analyzed and assigned a risk value of high, moderate, or low. The risk value is based on available biological information and subjective judgment. Although results suggest that climate change will affect forest health, uncertainty arises regarding the degree of climate change that will occur; pathogen biology under changing climate; the effects of changing climate directly on the host; and the interactions between the pathogen, host, and climate.