撹乱履歴がヒノキ－アスナロ老齢林の構造と動態に与える影響
| Autor: | ASAI, Takahiro, HOSHINO, Daisuke, NISHIMURA, Naoyuki, YAMAMOTO, Shin-Ichi |
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| Jazyk: | angličtina |
| Rok vydání: | 2003 |
| Předmět: | |
| Zdroj: | 名古屋大学森林科学研究. 22:1-12 |
| ISSN: | 1344-2457 |
| Popis: | To evaluate the effects of different disturbance histories (typhoon vs. human disturbances) on the structure and dynamics of an old-growth forest, we investigated the structure and ten-year dynamics of a stand with no evidence of disturbance (Stand N), a stand with severe typhoon disturbance (Stand T), and a stand disturbed by humans (e.g., by selection cutting : Stand H). The study site was located in an old-growth Chamaecyparis obtusa (canopy dominant) – Thujopsis dolabrata (understory dominant) forest in the Akasawa Forest Reserve of central Japan. Stands T and N had the highest and lowest percentage of canopy gaps, respectively. The total density and basal area of canopy stems were highest and largest, respectively, in Stand N, and lowest and smallest in Stand H, but the reverse trend was observed for understory stems. Generally, mortality and recruitment were very low among canopy stems, but high among understory stems. The recruitment rate of understory stems was clearly higher than the mortality rate in Stand T, while the reverse was typical in Stands N and H. Various states of mortality were observed among understory stems. In Stands N and T, understory stems tended to be physically damaged, whereas in Stand H, we recorded more standing dead trees than physical damaged trees. Different disturbance histories clearly affected the structure and dynamics of this forest, although disturbance itself induced understory regeneration. Human disturbance such as selection cutting enhanced understory regeneration of T. dolabrata more than C. obtusa, due to ensuing light conditions that favored the growth of T. dolabrata in the understory. 異なる撹乱履歴(自然、人為)が、赤沢ヒノキ老齢林の構造と動態に与える影響を評価するために、無撹乱林分、台風撹乱林分、択伐による人為撹乱林分の、3林分の構造と10年間の動態を調査した。林冠ギャップ率は、台風撹乱林分で最も高く、無撹乱林分で最も低かった。林冠木の幹密度、胸高断面積合計ともに無撹乱林分で最も高く大きく、人為撹乱林分で最も低く小さかった。反対に下層木は人為撹乱林分で最も高く大きく、無撹乱林分で最も低く小さかった。林冠木における10年間の枯死・加入は殆どない一方、下層木でより多く発生した。台風撹乱林分において、下層木の加入率は枯死率よりも高いが、ほか2林分では逆傾向にあった。無撹乱および台風撹乱林分における下層木の枯死状態は、主に物理的損傷である一方、人為撹乱林分では主に立ち枯れであった。これらの結果より人為撹乱がアスナロの更新と競争による枯死を促進させているなど、撹乱履歴の違いに対するヒノキ老齢林の構造と動態の影響が明らかとなった。 農林水産研究情報センターで作成したPDFファイルを使用している。 |
| Databáze: | OpenAIRE |
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