報告書番号

U98061

タイトル（和文）

森林の再生過程に関する研究 -－ブナ林群落の組成，構造と再生－-

タイトル（英文）

Fundamental Study of Regeneration Process of Forests - Floristic Composition, Stand Structure and Regeneration Process of Beech (Fagus crenata) Forests at Tambara Highland, Central Japan

概要 （図表や脚注は「報告書全文」に掲載しております）

人為的な環境改変に対する森林の反応および森林の修復創成技術の検討に必要な基礎的知見を得るため，群馬県玉原高原におけるブナ林群落の組成と構造，再生過程について調査した。調査地域のブナ林はブナ－チシマザサ群集に位置づけられ，地形的な立地条件と対応する２亜群集，４変群集に区分された。組成で区分された群落タイプは高木性樹種の樹高階分布にもとづく構造タイプと対応し，各群落タイプの更新状態が推測された。約50年前に強度の異なる伐採を受けた群落では立地条件に対応した先駆性樹種やサクセッサー樹種によって林冠が修復されていたが，攪乱前のブナ林とは組成・構造的に異なっていた。群落の再生過程は伐採の強度に関わらず基本的に同じであったが，群落の立地条件やギャップサイズなどが再生に関与していると判断された。

概要 （英文）

The purpose of this study is to obtain basic data for estimating the expected changes in forest ecosystems due to human impacts. From the point of view mentioned above, the present report aimed to clarify the floristic composition, stand structure and regeneration process of Beech (Fagus crenata) forests at Tambara Highland, Gunma Prefecture. On the floristic composition, the beech forest was identified to the association, Saso kurilensis-Fagetum crentae which was typical type in Japan Sea side. This association subdivided into two subassociations; Aesculetosum and Typicum. The Aesculetosum included two variants; typical variant and Viburnum furcatum variant. On the other hand, typical subassociation included two variants; typical variant and Thujopsis dolabrata variant. Distributional pattern of each vegetation type was almost identical to the beech forests in the Japan Sea side. On the stand structure, five different types of the stands were distinguished based on the height distribution of high-tree species. The stands of type 1 and 5 were not accompanied by young plants of F. crenata, suggesting that the regeneration of F. crenta was not successive. Type 2 and 3 were accompanied by some young beeches, however height distribution was not continuous. Type 4 represented continuous height distribution of F. crenata, suggesting successive regeneration of beech forests. To clarify the regeneration process of the beech forests which had been influenced by selective cutting, the complete enumeration was carried out at four plots. Plot 1 and 2 distributed the teritorry of the Aesculetosum, and plot 3 and 4 were typicalsubassociation. Plot 1 had many gaps by selective cutting whereas plot 2 had no gaps. Plot 3 was nearly clearly cut, while plot 4 had no experience of cutting. Plot 1 and plot 2 had a remarkable difference in number of F. crenata and Acer nipponicum. Plot3 and plot 4 were also similar in tree composition, however, plot 3 had few F. crenata and successor species (Acanthopanax sciadophylloides, Plunus grayana et al.) which had small crowns were mixed together. By analysing the change in the number of trees during 1991 to 1997 in each plot, more than 10 individuals were withered and dead. Especially, remarkable change could be seen in the plot 1 and 3. The change of seedling number in each plots were also surveyed, and there were many seedlings after mast year. However, most of the germinated seedlings were dead within a year. As we have seen, a number of ecological variations could be seen in the floristic composition, stand structure and regeneration process of the Beech forests. The accumulation of data on a lot of condition examples is needed hereafter.

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