Mountain pine beetle attack in ponderosa pine: Comparing methods for rating susceptibility - Introduction

Two empirical methods for rating susceptibility of mountain pine beetle att ack in ponderosa pine were evaluated. The methods were compared to stand da ta modeled to objectively rate each sampled stand for susceptibly to bark-b eetle attack. Data on bark-beetle attacks, from a survey of 45 sites throug hout the Colorado Plateau, were modeled using logistic regression to estima te the probability of attack on individual trees from tree and stand variab les. The logistic model allowed flexibility to easily scale results up to a stand level for comparison to the empirical methods. The empirical method, developed by Munson and Anhold, most closely correlated to the logistic re gression results. However, the Munson/Anhold method rated all 45 study site s as either moderately or highly susceptible to bark-beetle attack, which r aises concern about its lack of sensitivity. Future work on evaluating risk of bark-beetle impact should consider more than stand characteristics.