Models to predict the moisture content of lodgepole pine foliage during the red stage of mountain pine beetle attack

Abstract

Models were developed and evaluated to predict the moisture content of dead needle foliage of lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) trees during the red stage of mountain pine beetle (Dendroctonus ponderosae Hopkins) attack. Data for model development were obtained from hourly measurements of moisture content during four 25-hour periods spread across the 2013 fire season at a site in southeastern Wyoming. Calibrated models for two popular operational fine fuel moisture models are presented as well as more complicated bookkeeping-system type models derived from diffusion theory. The models were evaluated against two data sets: one from measurements made in northeastern Utah, and another in British Columbia, Canada. All models generally performed well when compared to the data from northeastern Utah but did not perform as well when compared to the dataset from British Columbia. The calibrated operational fine fuel moisture models appear to be nearly as accurate or more accurate than the more complicated bookkeeping-system type models and are recommended for field use.