Basic Density of Norway Spruce. Part II. Predicted By Stem Taper, Mean Growth Ring Width, and Factors Related To Crown Development

Håkan Lindström

Abstract


In a fertilization trial near Stråsan, central Sweden, six net parcels of Norway spruce (Picea abies) planted in 1957 and clear-felled in 1989 were used to evaluate basic density in relation to growth rate. Growth rate had been regulated by annual dressings of nitrogen, phosphorus, and potassium. The six parcels represented two unfertilized, two medium, and two heavily fertilized treatments. Various thinning procedures were applied to each stand in 1982 and 1988. Based on the author's published paper of cambial activity regulation, this study focused on variables related to crown development and basic density. Three sets of predictors were used: stem taper, mean ring width, and factors related to crown development. Stem taper was found to be a significant predictor of basic density, with r2 varying from 0.34 to 0.60, depending on the form of the model. Mean ring width was found to be a significant predictor of basic density, with r2 = 0.61. Mean ring width was found dependent on factors related to crown development. Tree height, diameter outside bark, tree height x diameter outside bark, site quality, stand density, and thinning procedure were found to be significant predictors of growth ring width, with r2 = 0.95. Factors related to crown development were used in a multivariate regression model in which tree height, tree height x diameter on bark, and thinning procedure were found to be significant predictors of basic density, with r2 = 0.68 at tree level. At stand level, volume production, stand density, and thinning procedure were found to be significant predictors of basic density, with r2 = 0.99.

Keywords


Crown development;<i>Picea abies</i>;stem taper;growth ring width;basic density;wood density

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