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An analysis of the growth of young stands of western red cedar and associated species on the University of British Columbia research forest, Haney, British Columbia Osborn, John Edward

Abstract

Breast height radial growth of 165 western red cedar (Thuja plicata Donn), 14.5 western hemlock (Tsuga heterophylla (Raf.) Sarg.) and 33 Douglas fir trees (Pseudotsuga menziesii (Mirb.) Franco), in young natural stands on the eastern side of the University of British Columbia Research Forest near Haney, B.C. was analysed. Individual tree parameters measured included breast height diameter, total height, age at breast height, radial growth over last five and ten years, crown width, live crown length, tree class, live crown ratio, height/age ratio, crown width/breast height diameter ratio, and height/ crown width. Stand parameters measured were number of trees per plot, average breast height diameter of plot, and basal area per acre of plot. Plots were of variable radius as determined in prism cruising. Growth was investigated from results of simple correlation coefficients and several multiple regression analyses computed on an IBM 7040. Causes of variation in growth were assessed by studying interaction of variables affecting growth patterns. Individual species have distinctly different modes of growth. Species react differently to changes in stand density. Radial growth can be determined from measurements of tree crowns; and crown development reflects changes in stand density. Difference between species are found as crown development varies with stand density changes. Crown dimensions of western hemlock are least sensitive to changes in stand density as measured by basal area per acre, crown width/breast height diameter, live crown ratio, or height/crown width. An understanding of how crown dimensions change with variation in stand density can be used to refine predictions of tree radial growth derived from crown measurements.

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