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Analysis of biomass, biomass sampling methods, and weight scaling of lodgepole pine Johnstone, W. D. (Wayne David)

Abstract

Tree and tree component weights of 63 forest-grown lodgepole pine trees were investigated. Data were collected from one tenth-acre plot located in south western Alberta. Both graphical and multiple regression techniques were used. Of the independent variables tested, tree basal area was most closely related to the component weights, with the exceptions of bole bark weight and total stem dry weight. The fresh and dry weights of bole bark were most closely associated with tree height, and total stem dry weight was most closely associated with dbh. Very reliable estimates of tree and tree component weights were obtained using regression techniques and the independent variables previously mentioned. The proportions of the component weights of the total tree weights were determined. The proportions were highly variable and widely dispersed about the mean. The tree characteristic most closely associated with the various proportions varied for the component being analysed. The proportion of the total tree weight contained in the stem, slash, bark and bole wood decreased with increasing tree size. The proportion represented by the needles, branches, merchantable stem, and crown increased with tree size. The crown and needle characteristics of lodgepole pine were investigated. Tree size, whether measured as stem weight in pounds or cubic foot stem volume (ob), was most closely correlated with dry needle weight (in pounds). The number of needles per cubic foot of stem volume increased with increasing tree size. The needle characteristics of lodgepole pine are highly variable. Needle length was significantly related to needle width. Needle length was not significantly related to any tree characteristics. The need to develop reliable sampling methods for biomass and fire control studies was discussed. Double sampling with regression appeared to offer accurate estimates with a minimum of weight measurement. The number of trees required to obtain a sample mean within plus or minus 10 per cent of the population mean at the 95 per cent confidence level is too large to be practical for most biomass and fire control studies. A higher standard error of estimate is probably more desirable, thus allowing a greater number of conditions to be sampled in order to increase the representativeness of the study. The mutual relationship between tree weight and tree volume was investigated. Tree volume was highly correlated with tree weight. Reliable estimates of tree weight were obtained from tree volume. Variation in moisture content and specific gravity, within and between trees was analyzed. These variables were surprisingly uniform and appear to pose only minor problems in weight scaling, for lodgepole pine.

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