京都大学北海道演習林における "ヤチダモ" の育林学的研究 : 第III報 萌芽性ヤチダモの成長量について

Abstract

本演習林並びに塘路でおこなつたヤチダモの萠芽生林木の成長量調査の結果次のことが明らかとなつた｡ ① 樹高定期成長量は樹令に従つて減衰の傾向にあつて, 萠芽性林木としての特色をもつている｡ 総成長量は同一林地に成立している2次林とほぼ同様な成長経過を辿つている｡ ② 胸高直径定期成長量は壮令期に極大点をもつ凸型の成長曲線で示され, 従来の萠芽性薪炭林に見られるような漸時減衰の傾向は見られない｡ 総成長量は同一林地に成立している2次林よりも良好である｡ ③ 材積総成長は樹令50年で, 萠芽性ヤチダモは2次林の1.76倍を示し極めて良好である｡ ④ 幼令時の連年成長量は上長, 肥大成長ともに凹型の曲線で示され, 萌芽性薪炭林とは異なつた傾向にある｡ ⑤ 将来の広葉樹用材林施業にも萠芽更新をとりいれることの優位性を示していると推断される｡

In a partial area of Kyoto University forest in Hokkaido, there are sprouted Yachidamo forests, which are growing better than the seedling tree forest. Attending to these peculiar standing we tried to make clear the useful effect of regeneration of sprouts of Yachidamo by studying the following two matters, that is, (1) growth of height, diameter breast high, and volume of the sprouted Yachidamo, (2) comparing these growth with that of seedling trees. The result of this studying is as follows: (1) The periodic increment of height demonstrates tendency of decrease according to tree ages. This is a distinctive character as the sprouted trees. Total increment of height indicates nearly similar proceeding of growth to middle age seedling trees standing in the same forest as the sprouted trees. (2) The periodic increment of diameter breast high indicates the convex growth curve which has a maximum point in the middle period. Such a decreasing growth according to years as traditional sprouted fire wood forest is not appeared in this investigation. Total increment of height of the sprouted trees is better than middle age seedling trees standing in the same forest. (3) Total increment of the volume sprouted Yachidamo is 1.76 times as much as middle age seedling trees at 50 years old. (4) Current annual increment of the tree at younger age is obtained as concative curve which has a minimum point for both in height and diameter-growth. This is a different tendency from that of not similar as the sprouted fire wood forest.