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Title: 琵琶湖に侵入した特定外来生物オオバナミズキンバイの分類と生活史特性
Other Titles: Re-identification and life history characteristics of the invasive alien species, Ludwigia grandijlora in Lake Biwa
Authors: 稗田, 真也
Issue Date: 20-Mar-2020
Abstract: Invasive alien species, so called Ludwigia grandiflora, has been invading Lake Biwa, constituting a serious threat to the native ecosystem. To establish efficient control measures, the present thesis aimed to identify its biological entity and factors affecting· its invasiveness. Morphological and chromosomal investigations revealed its entity as L. grandiflora subsp. hexapetala, presumably derived from a horticultural variety, similarly as· in other distribution areas in Kinki district and Teganuma in Kanto district. The subspecies has three life forms; the floating-leaved, emergent and terrestrial forms, ·respectively dominant at different microhabitats across open water to waterside land, the property of which was regarded to account for its high invasiveness. Contrary to the conventional wisdom that the subspecies was entirely vegetatively reproducing, the subspecies could reproduce by seeds too. The seeds exhibited high germination rate after preserved in mud, but a native herbivorous insect and other environmental factors caused high mortality of the seedlings. オオバナミズキンバイとみなされる特定外来生物が琵琶湖に侵入し、在来生態系に対する脅威となっている。本研究では、有効な駆除策を構築するため、その生物学的実体と侵略 性をもたらす要因について検討した。形態、倍数性等を詳細に調べた結果、その実体は亜種ウスゲオオバナミズキンバイであった。本亜種には浮葉形、抽水形、および陸生形の3生活形が存在し、水辺から陸上にかけて各生活形で適応・繁茂することで高い侵略性を実現していた。従来の見解とは異なり種子繁殖することも分かった。種子は、泥中に保存された後に高い発芽率を示すが、在来食植者の食害も実生の重要な死因であった。
Description: 環課第60号
NII JaLC DOI: info:doi/10.24795/24201k116
Appears in Collections:博士学位論文

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