著者

河野 勝 日置 佳之 田中 隆 長田 光世 須田 真一 太田 望洋

出版者

Japan Society of Civil Engineers

雑誌

環境システム研究 (ISSN:09150390)

巻号頁・発行日

vol.25, pp.59-61, 1997

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Nowadays, ponds in urban parks as habitats of plants and animals are strongly required in order to maintain biodivesity. The authors investigated on present and past situation of aquatic plants and structure of ponds in urban parks by questionnaires which sent to management staffs of urban parks. 160 sample data from all parts of Japan. were analyzed for clarifying relationships between aquatic plants and some factors of ponds' structures.<BR>Consequently, following relationships became cleared.<BR>(1) Approximately 30% of ponds are made with waterproof sheets and area of them are limited below mostly 10, 000<SUP>2</SUP> The main reason that ponds' area are limited is difficulty of water supply.<BR>(2) Most of the substratum of natural or semi-natural ponds are mud or silt in contrast that gravel used in man made (artificial) ponds.<BR>(3) More than 50% of ponds have only hygrophyte and emerged plants. On the other hands floating plants and benthophyte disappeared in many ponds though they were existed in past. It is considered that floating plants and benthophyte are sensitive for environmental impacts such as eutrophication.<BR>(4) Four structural factors; area of ponds, waterproof, structure of ponds' shore, and origin of ponds are related each other. Also certain relationship between hygrophyte or emerged plants and area of ponds or structure of ponds' shore are recognized. However, these kinds of relationships are not exist between hygrophyte or emerged plantsand waterproof or origin of ponds.