富士山青木ヶ原における針葉樹林の分布と群落構造

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富士山北西麓山地帯の青木ケ原における針葉樹天然林の群落構造と分布について調査を行った。優占種を異にする種々の林相の森林内に43の調査プロットを設けてくわしく調査した結果，優占種並びに群落構造の違いによって，疎開アカマツ林，アカマツ林，ツガ－アカマツ林，ツガ林，ヒノキ－ツガ林，ヒノキ林及び落葉広葉樹林の7タイプが区別された。それらのうち，疎開アカマツ林は火山事跡地と伝えられる露出熔岩上に限って成立するもので，林床にアカマツの稚樹が多い。一方，アカマツ林は林冠が閉鎖しているが，林床にアカマツの稚樹がなく，代わってツガの稚樹が多い。ツガ－アカマツ林とツガ林はともにツガの優占する群落であるが，前者はツガの林冠層から超出するアカマツ大径木が特徴的である。ツガ林は青木ケ原で最も広い面積を占める。ヒノキ林と，ツガの大径木を伴うことで顕著なヒノキ－ツガ林は調査区域内では標高の高い方にみられる。前者には往々にして樹高20m以上，直径70cm以上のヒノキ大径木がある。上記針葉樹林のほかに，ブナ，イヌブナ及びミズナラの優占する落葉広葉樹林が，熔岩流の被覆を免れた土壌の深い立地に限ってみられる。これら各タイプの森林の群落構造を比較することによって，青木ケ原の熔岩露出地域には，アカマツ優占の林からツガの優占するものを経てヒノキ優占の林に至る遷移系列の存在が推定された。The distribution patterns and the community structure of natural coniferous forests were studied in Aokigahara area, located in the montane zone on the northwestern foot of Mt. Fuji and mostly covered by the lava flowed from this in 864 A.D. As the results of careful survey of 43 plots set in various stands of different dominant tree species, seven types of forests were distinguished on the basis of the dominant species and the structure of stands as follows: open Pinus forest, Pinus forest, Tsuga-Pinus forest, Tsuga forest, Chamaecyparis-Tsuga forest, Chamaecyparis forest and deciduous broadleaved forest. Among them, the open Pinus forests are restrictedly found on the laval area. The antecedant forests of them may probably have been destroyed by wild fire, and consequently lots of pine saplings are found on the forest floor. The Pinus forests have closed canopies, and are accompanied by many hemlock saplings but not by pine saplings. The Tsuga-Pinus forests and the Tsuga forests are both dominated by Tsuga sieboldii. But the former are characterized by a number of large pine trees mostly emerging from the hemlock canopy. The Tsuga forests occupy the large part of Aokigahara area. The Chamaecyparis-Tsuga forests distinguished by the presence of large hemlock trees from the Chamaecyparis forests and the latter occur on higher elevations in the area. The Chamaecyparis forests are sometimes composed of large trees taller than 20m and larger than 70cm in diameter. Beside the above coniferous forests, the deciduous broadleaved forests dominated by Fagus crenata, F. japonica and Quercus mongolica var. grosseserrata trees stand restrictedly on the site free from the laval flow and covered by deep soil. Through the analyses of the structures of these forests, the succession in the sequence from Pinus-dominating forests, through Tsuga-dominating forests, to Chamaecyparis-dominating forests can be supposed on the laval sites in Aokigahara area.
東京大学大学院農学生命科学研究科附属演習林,The Tokyo University Forests,東京大学農学部林学科,現勤務地：台湾大学実験林管理處,| 現勤務地：千葉県立中央博物館生態園,Department of Forestry, Faculty of Agriculture, University of Tokyo,Present address: The Experimental Forests, College of Agriculture, National Taiwan Univerの論文

著者

中村俊彦
千葉県立中央博物館:生態・環境研究部

富士山青木ヶ原における針葉樹林の分布と群落構造

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