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    Wyświetlanie 1-4 z 4
    Tytuł:
    Znaczenie wspolczynnika zmiennosci w okreslaniu jakosci surowca drzewnego
    Autorzy:
    Barszcz, A
    Rutkowska, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/819428.pdf
    Data publikacji:
    1999
    Wydawca:
    Polskie Towarzystwo Leśne
    Tematy:
    surowce drzewne
    drzewostany swierkowe
    drewno swierkowe
    lesnictwo
    wspolczynnik zmiennosci
    jakosc
    pomiary
    wady drewna
    Źródło:
    Sylwan; 1999, 143, 07; 45-55
    0039-7660
    Pojawia się w:
    Sylwan
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Jakość surowca świerkowego pochodzącego z drzewostanów naturalnych (rezerwatowych) i drzewostanów pełniących funkcje gospodarcze
    The quality of spruce timber from natural stands (forest reserves) and managed stands
    Autorzy:
    Michalec, K.
    Barszcz, A.
    Wasik, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/52586.pdf
    Data publikacji:
    2013
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Technologii Drewna
    Tematy:
    drzewostany swierkowe
    drzewostany naturalne
    drzewostany gospodarcze
    surowce drzewne
    drzewa lesne
    swierk
    drewno swierkowe
    jakosc
    struktura jakosciowa
    wady drewna
    Opis:
    W artykule przedstawiono wyniki analizy porównawczej jakości surowca świerkowego pochodzącego z drzewostanów naturalnych (rezerwatowych) i drzewostanów pełniących funkcje gospodarcze. W analizach uwzględniono również wady drewna wpływające na wyniki klasyfikacji badanego surowca oraz częstotliwość ich występowania. Wytypowane do badań drzewostany zlokalizowane były w terenach górskich: w Sudetach i Karpatach. W wyniku przeprowadzonych analiz stwierdzono, że nieznacznie lepsze pod względem jakości surowca drzewnego są w porównaniu z drzewostanami naturalnymi (rezerwatowymi) drzewostany pełniące funkcje gospodarcze.
    The aim of this study is to determine the variation in the quality structure of spruce timber and to analyze the frequency of occurrence of trees with defects, including the generic structure of defects in natural stands (forest reserves) and stands serving economic functions. The study was conducted on 20 experimental plots located within the Sudeten and Carpathian Mountains, of which 10 were located in the area of nature reserves or national parks while the other 10 - in the managed stands (table 1). Each experimental plot constituted 5 or 10% of the area of the whole stand, depending on its differentiation. The following tasks were performed on the experimental plots: measurement of the breast-height diameter of each tree with a thickness of at least 7 cm, measurement of the height of each tree, quality assessment of the first section of the tree stem from the base along with its quality-dimensional class or group [Zasady... 2003], recording the types and varieties of wood defects. Analyzing the research material obtained, the stem of each tree growing on an experimental plot underwent simulated division into sections corresponding to the quality-dimensional classes and groups which could theoretically be distinguished over the whole length of a stem up to its top. The starting point was the quality-dimensional class noted in the butt section of the stem (section 1) during the field research. The above tasks included the use of the Radwański tables [Roczniki... 1956], which allowed the determination of the size and volume of each section of the spruce stems on the basis of the breast-height diameter and the tree height; wood defects, noted in field, were also taken into account. The material obtained was divided into 2 groups: data from the reserves and from the managed stands. For the material grouped in this way, juxtapositions were made of the average volumes of individual stem sections in quality-dimensional classes and groups of timber and the percentages of particular timber classes and groups in the two stand types were calculated. The material was also analyzed taking into account the generic structure of defects (percentages of individual trees with particular wood defects in a given group of stands). The next stage consisted in statistical analyses using the U-Mann-Whitney test, examining the significance of differences in the quality-dimensional structure of timber and the share of trees with defects between the two groups of stands. The research showed that trees growing in natural stands (reserves) are characterized by a greater average height, thickness (d1.3 and d1/2) and volume of individual trees as compared with the same characteristics of spruce trees in managed stands (table 2). Also, the average volume of the large-sized timber sections (WA, WB1, WB, WC, WD) of individual trees from natural forests dominated the volume of tree sections in managed stands. Despite that fact, the volume/ha of natural forest stands was lower (355.91 m3/ha) than of managed stands (380.27 m3/ha). By analyzing the quality-dimensional structure of the examined timber it was found that the proportion of higher quality timber classes (WA and WB) prevails in the managed stands, resulting in a lower share of the WC class of timber (fig. 1). Only the share of WB1 class timber prevails in natural stands. The managed stands also showed a larger share of medium-sized timber (groups S1, S2 and S4) as compared to natural forests. TheU-Mann-Whitney statistical test, however, did not show statistically significant differences in the timber quality structure between the natural and the managed stands (U = 49.00, Z = -0.0378, p = 0.9698). Subsequently, it was found that the proportion of trees with quality reduced by defects was higher in the natural stands (70.38%) as compared to the managed stands (67.13%). The main defect, decisive for timber quality, were knots (in both groups of stands). The share of trees with that defect was greater in the stands of natural origin (fig. 2). In those stands, there was also a larger share of trees with rot (external and internal rot) and unilateral curvatures. The managed stands demonstrated a share of injuries (overgrown and open ones) as well as bilateral and multilateral curvatures that was higher than in the natural stands. In conclusion, it should be emphasized that in the managed stands within the research area a higher quality of spruce timber as well as higher volume/ha were noted as compared to the natural stands (forest reserves). Stands in forest reserves are generally located at higher altitudes in the mountains or hardly accessible areas; their main purpose are protective functions, they also serve the purposes of research. In the stands situated in forest reserves there was reported, in comparison with the managed stands, a higher incidence of trees with a large number of knots and highly affected by rot. A frequent presence of such defects is inevitable there because this group does not undergo any management cuts that would improve timber quality. Moreover, the presence of rot is due to the advanced age of these stands. At the same time, what is disturbing is a large share of trees with injuriesin the managed stands. Given that spruce is very sensitive to mechanical damage of the stem, resulting in rapid development of rot, caution is recommended during forest management work and harvesting in spruce stands.
    Źródło:
    Drewno. Prace Naukowe. Doniesienia. Komunikaty; 2013, 56, 189
    1644-3985
    Pojawia się w:
    Drewno. Prace Naukowe. Doniesienia. Komunikaty
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Klasyfikacja surowca wybranych gatunków według norm polskich i Unii Europejskiej
    Classification of wood of selected tree species according to the Polish and the EU standards
    Autorzy:
    Michalec, K.
    Wąsik, K.
    Barszcz, A.
    Groń, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/989278.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Leśne
    Tematy:
    lesnictwo
    surowce drzewne
    drewno bukowe
    drewno debowe
    drewno jodlowe
    drewno swierkowe
    wady drewna
    jakosc drewna
    klasyfikacja drewna
    normy unijne
    normy polskie
    raw wood
    wood defects
    wood value
    softwood
    hardwood
    Opis:
    The aim of this paper was to perform a comparative analysis of the quality and the value of beech, oak, fir and spruce wood classified according to the Polish and the EU standards. The research was carried out in Lesko and Baligród forest districts (south−eastern Poland). The measurements of the investigated raw wood were taken at the upper landings. With regard to fir, spruce and beech 50 specimens per species were measured, while in the case of oak only 25 pieces were examined. Each specimen was classified in respect of its quality and size according to the Polish standards (PN) and the European Union (PN−EN) standards. Then, the results of both classifications were compared in terms of the share of volumes of particular wood quality classes, the impact of wood defects on the raw wood classification results, and the value of wood determined by the means of both standards. With regard to the beech wood, the share of the poorest class D upon applying PN−EN was smaller than that for PN norms. This decrease was in favour of other classes, due to which the value of the entire beech wood increased by ca. 16%, when classified with the use of the EU standards. The oak wood revealed a slight increase in the share of wood volume in the class C and a decrease in the class D of PN−EN when compared with the Polish norms. The value of the oak wood classified with the use of the EU standards was merely by 2.3% higher than that of the Polish norms. With regard to the softwood (fir and spruce), a decrease in the share of wood of the class C in PN−EN was recorded, which was in favour of the classes B and D. The value of raw wood classified by means of the EU standards was lower for both of the coniferous species. The decrease for fir accounted for 13.3%, while for spruce it was only 1.5%. For the evaluation of the softwood, Polish classification was more profitable, whereas for hardwood the EU standards were more favourable.
    Źródło:
    Sylwan; 2016, 160, 06; 459-465
    0039-7660
    Pojawia się w:
    Sylwan
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wpływ wad drewna wielkowymiarowego na przychody z jego sprzedaży
    Effect of defects on income from the sales of large dimension timber
    Autorzy:
    Szramka, H.
    Bieniaszewski, T.
    Auguścik, L.
    Bobek, J.
    Adamowicz, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/987045.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Leśne
    Tematy:
    lesnictwo
    ekonomika lesnictwa
    surowce drzewne
    obnizenie jakosci
    drewno wielkowymiarowe
    wady drewna
    drewno
    sprzedaz
    przychody
    Nadlesnictwo Zaporowo
    forest stands
    health
    timber
    wood defects
    forest economics
    Opis:
    Harvested timber has many various wood defects. Analyses were carried out on material collected in Zaporowo Forest District (northern Poland). Results show that various defects were found in 35% of harvested timber on average. The share of timber with defects varied among individual species (pine – 44%, spruce – 22%, oak – 14%, birch – 9%, beech – 5%, lime and larch – 2% each, hornbeam and alder – 1% each). The individual wood defects appeared in harvested timber with following frequency: knots – 55%, knobs – 22%, foreign bodies – 7%, curvature – 5%, inner rot – 5%, galls – 2%, blue stain – 1%, insect holes – 1%, false heartwood – 1%, and cracks – 1%. Timber defects resulted in reduction of income from the sales. A decrease in income caused by various defects amounted from 0.07 PLN/m3 for brown sap stain to 68.83 PLN/m3 for knots. The greatest effect of wood defects on the reduction of income from sales was recorded for oak timber (518.30 PLN/m3), while the smallest for aspen (4.63 PLN/m3). Due to the fact that in almost all analysed tree species the dominant effect on the reduction of income from timber sales was caused by knots (open knots and knobs) systematic solutions need to be found in order to reduce the effect of this defect. It is particularly important in the case of oak timber, where a decrease in income from timber sales connected with this defect was the greatest.
    Źródło:
    Sylwan; 2017, 161, 03; 238-246
    0039-7660
    Pojawia się w:
    Sylwan
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-4 z 4

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