Analysis of the growth of Hinoki (Chamaecyparis obtusa) and invading broad-leaved trees in an unsuccessfully managed plantation : A case study of a 24-year-old Hinoki plantation in Miyama, Kyoto Prefecture
| Autor: | Shimada, Shumpei, Takeuchi, Michiyuki |
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| Jazyk: | japonština |
| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | 森林研究. 75:11-17 |
| ISSN: | 1344-4174 |
| Popis: | 京都府美山町の24年生ヒノキ不成績造林地に調査プロットを設定し, サンプル木の樹幹解析によって材積成長の経過を解析した.その結果, ヒノキのサンプル木の材積成長速度が増加を続けていたのに対し, 上層広葉樹のサンプル木の半数以上において, 樹高が林冠に達する時期に材積成長速度が頭打ちになるか, 減少し始めていることが明らかになった.今後この林を, 手入れせず放置した場合, 旺盛な成長を続けているヒノキが益々優勢になると考えられた.広葉樹の活力が減退している要因としては, ヒノキと広葉樹間の競争のみならず, 同じ株内の萌芽幹どうしの競争の影響が小さくないことが示唆された.また, この林では有用広葉樹を多く含む侵入広葉樹が上層木の約3割を占めていたことや, 植栽されたヒノキの多くが雪害やクマ剥ぎ被害を受けていたことから, ヒノキの単純林を目標とするより, より広葉樹の混交率の高い針広混交林として管理することが望ましいと考えられた.広葉樹の成長を促進するためには, ヒノキの間伐及び, 広葉樹どうしの競争を緩和するための株整理が必要であると考えられた. The volume growth of trees in an unsuccessfully managed plantation of Hinoki (Chamaecyparis obtusa) invaded by broad-leaved trees was analyzed in Miyama, Kyoto Prefecture. Although the volume growth rate of more than half of the broad-leaved trees stopped increasing or began to decrease just after they reached the canopy, Hinoki continued to increase at a constant rate. This suggests that Hinoki will eventually predominate over the broad-leaved trees in the upper stratum. The factors affecting the decline in the vitality of the broad-leaved trees included not only competition between Hinoki and the broad-leaved trees, but also competition among broad-leaved trees that originated as sprout stems from the same individuals. One third of the upper stratum trees was broad-leaved trees including valuable species. Most of the Hinoki had been damaged by snow or debarked by bears. Therefore, it was suggested that this forest should be managed to be converted to a forest in which broad-leaved trees are dominant. To make the broad-leaved trees more dominant, thinning of the Hinoki and cutting of the broad-leaved trees and some stems in coppicing trees in the area with dense individuals are required. |
| Databáze: | OpenAIRE |
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