Severity rating systems are fundamental to understanding the impacts of disturbance agents in forest stands. The balsam woolly adelgid (BWA), Adelges piceae (Ratzeburg) (Hemiptera: Adelgidae), is an invasive forest pest in North America that infests and causes mortality in true fir, Abies spp. There is currently no single system for...
Mountain pine beetle, Dendroctonus ponderosae Hopkins, is a primary agent of forest disturbance in western North America. Episodic outbreaks occur at the convergence
of favorable forest age and size class structure and climate patterns. Recent outbreaks have exceeded the historic range of variability of D. ponderosae-caused tree
mortality affecting ecosystem...