In pursuit of more efficient tree management along Yoshino River

リバーフロント研究所報告 第 31 号 2020 年 9 月

自然環境グループ 研 究 員 菊地 則雄
自然環境グループ 次 長 都築 隆禎
主席研究員 宮本 健也
自然環境グループ 研 究 員 川村 設雄

近年、気候変動の影響等により、豪雨による災害が頻発化・激甚化していることを受け、「防災・減災、国土強靭化のための 3 か年緊急対策」が閣議決定された。この中で、治水安全度向上のための施策の一つとして、樹木伐採が全国の河川で実施されており、吉野川においても樹木伐採が進められている。

キーワード: 樹木管理、萌芽再生、伐採、モニタリング調査計画、試験施工

Trees along a river are an important part of the riverine environment and the local landscape. But they can obstruct flood control by obstructing river flow. Driftwood can block a river channel flowing under a bridge.
In response to the increasingly intense and frequent disasters caused by heavy rains associated with climate change and other factors, the Japanese Cabinet approved three-year measures for urgently preventing and mitigating disasters, and building up national resilience. One of the measures for pursing greater safety with more robust flood control is felling trees along rivers across Japan. The Yoshino River is no exception.
Willow and bamboo groves account for a major part of trees growing along Yoshino River. These trees sprout and grow back soon after they are felled. Such quick recovery complicates tree control.
This paper is intended for the development of a more effective method of controlling trees along Yoshino River. Toward this aim, it compiles case studies of methods for curbing reforestation along other rivers. Comparison of these tree control methods was sought by planning tests and monitoring surveys.