Changes in Cellular Characteristics and Qualities of Matured and Juvenile Wood from Reforested Tree of Pinus koraiensis

잣나무 조림목(造林木)의 조직특성(組織特性)의 변동(變動)과 성열재(成熱材)·미성열재(未成熱材)의 재질(材質)

Pinus koraiensis is one of the most important reforestation species which had widely been planted around the country. Therefore, there are great research needs on the fundamental properties of wood to extend the frequency of uses and adequate availabilities. Research results on the characteristics of anatomical wood properties and changes are summarized as follows: 1. At a horizontal direction of tree trunk, the tracheid length at outer wood gradually becomes shorter as it reaches to pith. The tracheid length having between 32 and 42 annual rings showed over 2.5 times longer than that of pith, and also its length increases from the bottom to the top of the stem. 2. The tracheid diameters in latewood showed a little fluctuations, and the shortest near to the pith in earlywood. The tracheid diameters in earlywood are more than 2 times those of latewood, and the differences between the mature and juvenile wood in earlywood are less than 10${\mu}m$. 3. The tracheid wall thickness in early wood showed a little fluctuations. On the contrary, tracheid wall thickness in latewood rapidly increases from the pith to the bark. The tracheid wall of mature wood showed 10 to 20% thicker than that of juvenile wood. 4. The fibril angle at the secondary walls of tracheid within an annual ring showed higher degree in earlywood than that of latewood. The highest tracheid fibril angle was observed at around the pith of both earlywood and latewood. Then, fibril angle slowly decreased toward outer wood, and was stabilized after 15 years. 5. Structural boundaries between mature and juvenile wood from Pinus koraiensis are divided by 13 to 19 annual ring and distance of 5 to 8cm from the pith.