On the Pith-damaged Wood of Larix leptolepis Gorden

낙엽송(落葉松)(Larix leptolepis Gorden)의 심부재(心腐材)

This study was carried out to investigate the cause of pith-damaged wood formation, the state of growth, and difference of chemical composition of Japanese Larix(L. leptolepis Gorden). 1. Larix grew normaly to 10 years, and the volume increment was 32.4%. But it was gradually decreased to 19.4% from 11 to 13 years that the heartwood damage was occurred. Therefore, the volume increment was decreased 13%. The decayed wood was formed from fire wound portion of bark by forest fire. The volume loss from pith-dagmaged wood occurred by forest fire was more than 20%. 2. On the ash content, heartwood(0.05%) and pith-damaged wood(0.08%) was lower than sapwood(0.29%). The difference of extractive contents are considered the reason. It is considered that this ash content difference is depend upon the extractive contents among sap, heart and decayed wood parts. Holocellulose contents were from 54.3% to 59.3% and there were no difference among heartwood, pith-damaged wood, and sapwood, On the pentosan contents, heartwood(6.3%) and pith-damaged wood(6.6%) were higher than sapwood. Lignin contents of pith-damaged wood was tower than heartwood (34.4%). This seems to weaken all kinds of wood strength.

낙엽송의 심부후재(心腐朽材) 형성 원인과 성장상태(成長狀態) 및 그의 조성분(組成分) 차이를 구명하기 위한 실험이다. 1. 낙엽송이 정상적인 생장을 한 10년생 까지는 그의 성장율이 32.4% 이었으나 심부피해가 있는 11-13년 사이는 19.4%로 13% 점감하고 있다. 그리고 심부후재 형성은 산화(山火)에 의한 수피(樹皮)의 화상부분(火傷部分)부터 이루어지고 있다. 낙엽송 임지(林地)의 산화피해로 생기는 심부후재로 인한 재적(材積) 손실(損失)은 약 20% 이상이 되고 있다. 2. 조성분에 있어 탄분(炭分) 함유량은 심재가 0.05%, 심부후재부가 0.08%로 변재 0.29%에 비하여 적은데 이러한 원인은 유출성분(抽出成分) 함량 차이에서 오는 것으로 볼 수 있다. Holocellulose 함유량은 54.3%에서 59.3%로 심재, 심부후재부 그리고 변재 사이에 차이가 인정되지 않는다. Pentosan 함유량은 심재 6.3% 및 심부후재부가 6.6%로 변재보다 많았다. Lignin 함유량은 심재 34.4% 보다 심부후재부에서 감소되고 있는데 이러한 현상은 목재의 제강도(諸强度)가 열화(劣化)된다고 본다.