Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài: Density of juvenile and mature wood of selected coniferous species. | JOURNAL OF FOREST SCIENCE 57 2011 3 123-130 Density of juvenile and mature wood of selected coniferous species V. Gryc H. Vavrcík K. Horn Faculty of Forestry and Wood Technology Mendel University in Brno Brno Czech Republic ABSTRACT The objective of research was to determine the density of juvenile JW and mature wood MW of selected coniferous species growing in the Czech Republic. The research included the wood of Norway spruce Picea abies L. Karst. Scots pine Pinus sylvestris L. and European larch Larix decidua Mill. . The juvenile wood density close to the pith was 410 kg-m-3 for spruce 391 kg-m-3 for pine and 573 kg-m-3 for larch with 12 water content. Mature wood in the peripheral parts had the higher density in all species - spruce 516 kg-m-3 pine 552 kg-m-3 and larch 652 kg-m-3. The highest difference the difference of 161 kg-m-3 between juvenile and mature wood was found out in Scots pine. The large difference in the wood density of pine is caused by a considerable difference in the mean ring width of its juvenile and mature wood. Further it was proved that wood density decreases with the increasing ring width while wood density increases with the increasing proportion of latewood. Keywords density juvenile wood larch mature wood Norway spruce Scots pine In the last decades with the development of wood processing technology logs of smaller diameters have been processed. This means that the end products always contain juvenile wood JW . The structure and properties of this wood highly differ from those of mature wood MW . Juvenile wood is to be found mainly in the central part of the stem and also in the peripheral and upper parts Rendle 1959 Panshin De Zeeuw 1980 Zobel Sprague 1998 . One of the first definitions was formulated by Rendle 1959 who said that juvenile wood is the secondary xylem formed during the early life of the tree. From the anatomical aspect juvenile wood can be characterized by a gradual change of dimensions and corresponding changes in .
