ロシア極東タイガにおける更新動態の特徴とクローン成長による個体群維持機構について

• Main Author: 本間, 航介
• Format: Article in Journal/Newspaper
• Language: Japanese
• Published: 北海道大学低温科学研究所
• Subjects: 400; Duff; taiga
• Online Access: http://hdl.handle.net/2115/59094; https://doi.org/10.14943/lowtemsci.73.133

ロシア極東部のタイガの更新動態の特徴について, 筆者らがカムチャッカ半島で行った研究を中心に考察した. タイガには山火事による一斉更新プロセスと山火事の合間に生じる連続的プロセスが存在し, 連続的プロセスの中でギャップ更新が進まず倒木更新や前生稚樹更新および地際萌芽からの更新が支配的であること, 稚樹が同種の成木林冠下に集中分布するため空間構造の変化が起きにくいことが指摘された. また, シラカンバやヤマナラシのクローン成長戦略は山火事後の一斉更新において大きな役割を果たし広葉樹優占林分を成立させる主要因となり, 山火事の大半を占める表層火災は相対的にタイガの植生を針広混交林から広葉樹の萌芽林にシフトさせる可能性が示された. We evaluated the characteristics of the regeneration process of taiga in Far East Russia. Regeneration of taiga involves two types of processes:1)large scale simultaneous regeneration induced by forest fire;and 2)small scale continuous regeneration without fire(such as,e.g.,gap dynamics). Our study showed that the simultaneous regeneration was mainly driven by vigorous clonal growth of two deciduous broadleaved species (Betula platyphylla and Populus tremula),while two conifer species (Picea ajanensis and Larix cajanderi)could regenerate by seed in limited safe sites. The root-suckering strategy of P. tremula seemed to be highly adapted to surface fire (flame combustion), which occurs repeatedly in the boreal forest. In the continuous regeneration, gap regeneration was not successful for most canopy tree species. This is because the duff layer of the soil surface prevented seeds from germinating,and because the environment in the gaps in the boreal zone was too stressful for juveniles to survive. Juveniles of the two conifer species and seedlings of B. platyphylla showed aggregated spatial distribution under the canopy of adult trees. Except for post-fire regeneration, regeneration under the canopy of adult trees seemed to be the main regeneration pattern in boreal forest