No.244 研究課題 / Project
多摩川河川敷の植生遷移における生存戦略としてのアレロパシーの関与Influence of allelopathy as a survival strategy to the succession on floodplain vegetation of Tama River.| 学術研究 Academic Research |
No.244 |
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| 代表研究者 Principal Investigator |
渡邊 泉 Izumi Watanabe |
| 所属（採択当時） Affiliation |
東京農工大学農学部助手 Tokyo University of Agriculture and Technology |
| 研究内容要約 Research Summary |
近年、劇的な環境変動が指摘される都市河川、多摩川の河川敷に着目し、植生遷移に及ぼすアレロパシーの影響解明を行った。くわえて、化学的な環境変化である酸性雨が、生存戦略としてのアレロパシー活性に及ぼす影響評価も試みた。 試験は、多摩川河川敷で実際に生育する植物種を採取し、そのアレロパシー活性を検定することで主に以下の点を明らかとした。 1. 生態系のかく乱が懸念されている外来の侵入種および数種の在来種も強い他感作用を有し、生存戦略に寄与している可能性が推察された。 2.河川敷植生の構成種は生長とリンクした他感作用活性を示し、季節に依存した変化にアレロパシーの関与も推察された。 3.河川敷の幅広い化学環境、とくに土壌pHはアレロパシー活性の強弱に影響を及ぼす可能性が示唆された。 4.酸性雨の降下は、とくに侵入種のアレロパシー活性を助長させる可能性が示唆され、大気環境の保全は河川敷植生のかく乱を防ぐ可能性が考えられた。 Recently, drastic environmental changes are pointed out at urban river. Tama River that is a typical urban river in Japan was focused on, we attempted to elucidate allelopathic activity and their effect on actual succession of floodplain vegetation at Tama River. In addition, we also attempted to suggest the chemical effects to allelopathic activity by acid rain. Weed species inhabiting on river bed and soils were collected during 2001 to 2003 and chemical analysis and bioassay of allelopathy were conducted. The summary of these results are showed as follows: 1. Strong allelopathic activities of some alien species and Aster Kantoensis were observed. This suggests that allelopathy of these plants is contributable to the actual succession of floodplain vegetation as a survival strategy. 2. The changes of allelopathic activity depending on growth stage were showed in almost all species inhabiting Tama River. Therefore it is suggested that interaction of activity between species might be affectable to the seasonal succession of vegetation. 3. The variations of chemical status such as water soluble ions and pH observed at soils from forest of Robinia pseudoacacia and river bed are affectable to the allelopathic activity of floodplain vegetation. 4. The possibility was suggested that acid rain promotes the allelopathic activity of alien species and this promotion contributes to the ecological invasion at Tama River. Therefore, conservation of urban atmospheric condition might lead to protection of original floodplain vegetation of Japan. |
| 共同研究者 Collaborators |
久野勝治（東京農工大学 農学部）・浦口晋平・石川恵理（東京農工大学大学院） |
| 研究全文 Full Text |
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