Effect of quality factors especially of sweep of poplar trees on assortment structure

The factors of quality which affect the sawing yield were researched for poplar plantations, from the aspect of the application of national standards for roundwood. The research was performed in the period 2002-2003 on two temporary sample plots, in poplar plantations Populus×euramericana I-214 aged 25 years. The sample plots were selected depending on the clone species, planting pattern, and plantation flood risk, and branch pruning. The analyzed quality factors are: knots, minimal dimensions, sweep, false heart, ovality and tapering. The measured data were processed according to the original methodology. Based on the study results, the significance of quality factors was ranked in two different stand situations. Of all the study factors, knots have the highest effect on log yield, which is especially significant in marking for cross cutting of the larger trees. The sweep of trees in poplar plantations with higher flood risk is greater compared to the sweep of trees in plantations which are in the zone protected from floods. In poplar plantation Populus×euramericana I-214 which is exposed to frequents flooding (OP-2), sweep is the third significant factor, compared to the plantation protected from floods (OP‑3), where sweep is the fifth factor according to significance. The effect of sweep in the plantation exposed to flooding is 2.4 times higher than the effect of sweep in the plantation protected from floods. Total value of the assortments made of tree trunk grows with the increase of tree diameter on both sample plots. This correlation is represented by the function Y=a·Xb, and the correlation between the variables is complete. The value of assortments of a certain quality for the study stand conditions can be calculated by the selected model functions, i.e. represented by assortment tables. This study shows inter alia, that there is not a unique model for all poplar plantations when the value percentage of assortments is determined, although they are homogeneous plantations by structural elements.