No.290 研究課題 / Project
多摩川における“ツル植物”の繁茂が河川生態系に及ぼす影響の解析・評価と対策指針の検討Analyzing and Evaluating the Effects of the Expansion of Vine Plants on the Ecosystem of the Tama River and Reviewing Guidelines for Ecological Managements| 学術研究 Academic Research |
No.290 |
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| 代表研究者 Principal Investigator |
佐々木 寧 Yasushi Sasaki |
| 所属（採択当時） Affiliation |
NPO河川生態市民モニタリング研究会 代表理事 Graduate School of Science and Engineering. Saitama University |
| 研究内容要約 Research Summary |
本調査では藪化の中心植物である外来生のアレチウリ、及び在来生のクズ、ヤブカラシ、カナムグラなどのツル植物を対象に生態的特性と管理手法についての検討を進めてきた。とくに多摩川の河川環境管理計画で設定された「生態系保持空間」は、在来ツル植物のクズが急速に繁茂、その景観を大きく変貌させ、種多様性の低下、鳥類や昆虫相などにも大きな影響を与えている。こうした今日的で新たな事態が生態系に及ぼす影響、対策に関する調査研究は極めて少ない。このような状況から本調査では、以下の二点を目的として実施してきた。 １．アレチウリの他、在来性のツル植物の生態・立地調査を行うとともに、既往の研究事例の整理、その生態的特性を把握、ツル植物の繁茂の問題点を明確にする。 2．在来性ツル植物の駆除対策を想定し、群落組成調査、土壌調査、バイオマス特性等を調査し，その生育特性を解析することにより駆除あるいは生態的管理手法の基礎的知見を得る。 調査・試験研究の対象地区は、多摩川直轄管理区間の河川敷全域とするが、「生態系保持空間」や「水辺の楽校」である狛江宿河原、大栗川合流点、日野－八王子、淺川合流点の各地区を重点的におこない、以下の詳細調査を進めてきた。 1）ツル植物の生態特性の調査 既存調査資料を使い河川地形変動を把握、空中写真や現地調査によって、ツル植物の群落組成繁茂、分布状況と群落の変遷を整理・解析を行った。 2）ツル植物の立地特性の調査 ツル植物繁茂地区の土壌立地と化学性、ツル植物ごとのバイオマス特性などの詳細調査し、その生育立地特性を明らかにした。 3）アレチウリや他のツル植物の分布状況と生態的特性について研究成果を集約し、多摩川をモデルとした管理手法、すなわち強制的排除の手法と生態学的管理の手法を全国に発信する。 多摩川に限らず河川の藪化・樹林化とツル植物の繁茂の問題は、全国的な傾向であることから、本研究の成果は広く全国に発信できるものである。とくに、外来植物やツル植物の繁茂と駆除という緊急的課題に河川管理者、市民の意識啓発と合意形成を行い、具体的な維持管理対策について協働で進めていく事業に対し、大きく寄与し得る。 ツル植物が繁茂して問題が指摘されている多摩川「生態系保持空間」 空間の今後の管理方向について、一定の指針を得ることができたことから、今後市民参加により駆除対策を試行、駆除地の植物群落の変動をモニタリングするなど具体的な事業を計画できる。 ※PDFファイルは圧縮して掲載しているため、見にくい場合がございます。元のサイズをご希望の場合は東急財団までメールにてご連絡ください。 This study examined the ecological characteristics and methods for managing vine plants, including the alien species, Sicyos angulatus, and the native Pueraria lobata, Cayratia japonica, and Humulus japonicus, which are the majority of plants that grow in the bush. At the “ecosystem preservation space” designated by the Tama River Environmental Management Plan, in particular, the native vine plants expand rapidly. Their expansion changed the landscape considerably, reduced biodiversity, and exerted tremendous impact on birds and insects. However, there is very few research work done on the impact of such new and contemporary occurrences on the ecosystem or on measures to cope with them. Under this conditions, this study was carried out with the following two objectives: 1. The ecological characters and habitats of native vine plants, besides the Sicyos angulatus, were studied and previous literature were sorted out to help understand the ecological characteristics and identify issues arising from the rapid expand of these vine plants. 2. Assuming what measures can be taken to eradicate the native vine plants, we conducted studies on the species composition of the vine community, the soil conditions, and properties of biomass, and analyzed the growth characteristics of these plants, in order to obtain basic knowledge of eradication methods as well as ecological management methods. The target area for the surveys and the experiments was the entire river bed area under the direct control of the Ministry of Land, Infrastructure, Transport and Tourism. The following detailed studies were carried out with emphasis on the “ecosystem preservation space” and “Riverside Fun Schools” in various areas, including the Komae Shukugawara river bed, the confluence site of Ookuri-gawa River, Hino–Hachioji, and the confluence site of Asa-kawa River. Listen Read phonetically Dictionary - View detailed dictionary 1）Investigation of the ecological habitats of vine plants The existing literature were used to understand the geo-morphological variations of the rivers. The growth of vine plant communities, distribution condition, and successions of communities were analyzed using aerial photographs and field surveys. 2）Investigation of the habitat characteristics of vine plants A detailed research was carried out to investigate the habitats and chemical properties of the soil where the vine plants thrive and the biomass properties of each type of vine plant in order to understand the characteristics of habitats that expand of vine plants. 3）The results of the research on the distribution and ecological habitats of Sicyos angulatus and other vine plants were summarized. Vegetation management methods using the Tama River as the model, that is, methods for eradicating these plants and methods for ecological management are to be disseminated nationwide. Not only the Tama River area, those problem with the expand of vine plants at rivers is an all over trend. The results of this study can be disseminated throughout Japan. In particular, this study can contribute substantially to projects that are aimed at raising the awareness of river management personnel as well as citizens about the urgent task to eradicate the expand of alien and vine plants and at fostering consensus and collaboration for taking specific conservation and management measures. “Ecosystem preservation space” of the Tama River are said to have the problem of expand of vine plants: We were able to come up with certain guidelines regarding the policy for managing these spaces. We are drawing up plans for specific projects to pick out the vine plants with citizen participation and to monitor the successions in plant communities at locales where the vine plants have been picked out. ＊There may be parts where it is difficult to read because the PDF file is compressed. Please contact the Tokyu Foundation by email if you need the original size. |
| 共同研究者 Collaborators |
浅枝 隆（埼玉大学大学院 応用生態工学 教授） 星野 義延（東京農工大学 植物管理学 助教授） 村上 雄秀（国際生態学センター 植物社会学） |
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