Original article Comparison of model forms for estimating stem taper and volume in the primary conifer species of the North American Acadian Region

balsam fir / red spruce / white pine / nonlinear mixed-effects / crown variables • The performance of ten commonly used taper equations for predicting both stem form and vol-ume in balsam fir [Abies balsamea (L.) Mill], red spruce[Picea rubens (Sarg.)], and white pine[Pinus strobus (L.)] in the Acadian Region of North America was investigated. • Results show that the Kozak (2004) and Bi (2000) equations were superior to the other equations in predicting diameter inside bark for red spruce and white pine, while the Valentine and Gregoire (2001) equation performed slightly better for balsam fir. • For stem volume, the Clark et al. (1991) equation provided the best predictions across all species when upper stem diameter measurements were available, while the Kozak (2004) and compatible taper equation of Fang et al. (2000) performed well when those measurements were unavailable