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The paper describes the accuracy of estimation of silver fir stem fresh mass on the basis of volume to weight conversion factor, derived from samples, collected from few different places along the stem. The research material contained 13 sample trees selected from homogenous 70−years old stand, situated in mountainous area of the Beskid Sądecki in Polish part of the Carpathians (S Poland). Volume over the bark of sample trees was calculated with section−wise method and the whole stem fresh biomass was directly weighted. For each sample tree three stem discs were collected at ⅙, ½ and ⅚ of tree height, their weight and volume were precisely determined and the biomass conversion factors (equivalent of stem density) were calculated. The assessment of the accuracy of whole fresh stem biomass was conducted according to five variants: for the biomass conversion factors derived from each individual stem disc (lower, middle or upper), from weighted mean density and on the basis of the constructed mixed model, where relative height and diameter were treated as fixed effects and influence of individual trees was included as a random term. The volume of sample fir stems ranged from 0.15 to 2.22 m³, while their fresh biomass varied between 138.1 and 1896.7 kg. Obtained results show that variation of the density was higher within stems than between them (coefficient of variation amounted to 8.4% i 3.3% respectively). The average density increased along stem, from 835.6 kg/m³ for lower part (⅙H) to 986.8 kg/m³ for the upper part (⅚H). Estimating the biomass on the basis of just lower stem disc resulted in the average relative error equal to –5.8%, while for middle stem disc the error was +1.2%, and for upper disc +11.3%. The use of conversion factors derived from weighted average density of all three stem discs resulted in average bias equal to –1,7% with standard error 1,0%. Despite the presence of mean bias of –2.3%, the constructed density model gave the most precise estimation of the stem biomass (standard error 0.7%), which indicates the reasons for its further improvements and usage.
The aim of this study was to assess the impact of the biosocial position occupied by the tree on the amount and structure of the biomass produced. The empirical material was measurements of biomass for 63 pines (21 for each of the I, II, and III Kraft classes). The total aboveground biomass of the trees was calculated as sum of following fractions: stem wood, stem bark, living branches, dead branches, shoots, needles and cones. It has been found that with a decrease of biosocial position of tree the share of a stem increases while share of branches in the overall biomass of the tree decreases. On the other hand biosocial position does not affect significantly the share of needles, dead branches and cones.
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The paper describes evaluation of spruce radial growth variability, based on of synchronized individual increment sequences (dendroscales). The empirical material were increment samples from 215 trees, growing on ten research plots in the Silesian and Żywiec Beskids. For each plot in each year there was calculated the raw average chronology, indexed chronology and the coefficient of variation for incremental indexes. In addition, an analysis of the occurrence of pointer years was performed. The observed medium-term changes of the analyzed incremental indices lead to conclusion that in the second half of the twentieth century, a certain external factor influenced the growth of tested spruces. Both the obtained results and the existing studies provide a basis for an assumption that this factor was mainly air pollution.
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