Crown profile equations for stand-grown western hemlock trees in northwestern Oregon

Crown profile equations were developed for stand-grown western hemlock (Tsuga heterophylla (Raf.) Sarg.) in northwest Oregon. The profile model uses a segmented approach, dividing the crown into an upper and lower portion at the point of the largest crown width (LCW). The model explains about 86% of the variation in crown width when LCW is known but only 66% when LCW is predicted using a model developed from a larger data set collected in the same area as the data for developing the crown profile models were collected. The model can be adjusted using measurements or predictions of LCW for western hemlock in other populations. Comparisons are made with the crown form of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco).