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Summary Results of an investigation into the relationships between tree size, relative bark thickness and bark yield of black wattle trees (Acacia mollissima Willd) are presented. The method of least squares was employed. Relative bark thickness has probably been introduced for the first time in South Africa as a controlled variable in an investigation of this nature. Significant differences in the ratio of bark thickness to diameter at breast height were established for different localities from which trees were selected for stripping. The bark weight equations permit the accurate determination of bark yields for research and management purposes. It is proved that indiscriminate application of bark weight tables to territories for which they were not prepared originally may lead to serious errors.

Summary Regression equations are derived in which relationships are established between stand density, crown size and basal area growth in pure, even-aged stands of P. taeda L. in the Piedmont of North Carolina, U.S.A. The findings are based on observations on 129 tenth-acre sample plots of variable stocking, age and site index. It is shown that: Single trees of given d. b.h. make more than twice as much basal area growth when basal area per acre is 60 square feet as when basal area is 140 square feet. Single trees of large diameters may make more than twice as much basal area growth as trees of relatively small diameters when basal area per acre is fixed. Basal area growth per acre generally increases as stocking in basal area declines from 140 to 60 square feet per acre. However, basal area growth per acre at relatively high stockings may be greater than basal area increment at lower stockings when the average d.b.h. of the trees at the high basal area is comparatively small. Basal area growth per acre ...

Summary The demand for wattle timber is increasing and reliable volume tables are needed. A timber volume table and alinement chart for Acacia mollissima Willd. in the Eastern Districts of Southern Rhodesia are presented in this paper. The mathematical relationship between timber volume and bark weight per tree was established. Regressions were fitted by the method of least squares.

Summary A brief review is first given of a few practical ways of regulating and expressing stand density. An illustration is then given of the application in even-aged stands of Pinus taeda in the native habitat of this species of a regression equation in which stocking is expressed in terms of number of trees per unit of area and total basal area. Not only does the equation permit the expression of the density of anyone plot as a percentage of the average stocking of a number of sample areas, but it enables the research worker to determine the ground area occupied by a tree of given size in the overstory or in the understory. Graphs are presented which illustrate the application of the tree-area equation, as this “stocking norm” is called.