Author Description

Several published tree volume equations are currently used in B.C., some in summaries of appraisal and inventory cruise data and some in studies of growth and yield and tree improvement of coastal Douglas-fir. These models are generally unsuitable for estimating volumes of small trees (under 5 cm in diameter) because of limitations of the model or sample data used. An opportunity to evaluate the existing tree volume prediction equations for coastal Douglas-fir was provided by a new large data set (about 1400 trees) recently acquired by B.C. Ministry of Forests and Lands in addition to the data used by the previous analysts. The study evaluated the prediction bias of the existing total and merchantable volume equations for coastal Douglas-fir small trees, arbitrarily defined here as trees having a diameter at breast height of less than 45 cm. In addition, new volume prediction equations were developed for the small trees, based on the expanded data set, to be used in summaries of Research Branch growth and yield plot data.