: The species diversity and population of dragonfly larvae are spatially different. In this study, we did mesocosm experiments to examine the effect of litter supply on the dragonfly larvae community. Size and species composition of dragonfly larvae and presence / absence of chironomid, a food resource for dragonfly larvae, were also controlled in the experiment. The results indicated that the litter provide the hiding places for small larvae, and consequently extend the survival time of them.Therefore, the litter supply regulates the structure of the dragonfly larva community.
摘要:都市域の小・中規模緑地を含む「地区スケール」における鳥類群集の種組成の構造的特徴を明らかにすることを目的とし, 千葉県松戸市を対象として鳥類調査を行った。各地区における β 多様性の高低および群集の入れ子構造の有無から調査地区は β 多様性が低く入れ子構造がある 1 地区,β 多様性が低く入れ子構造がない 3 地区,β 多様性が高く入れ子構造がある 2 地区,β 多様性が高く入れ子構造がない 2 地区に分類された。nMDS 法を用いた各調査地点の群集構造と環境要因の分析から,地区の鳥類 種組成構造が地形や土地利用の多様性などの景観要素と関連していることが示唆された。 キーワード:都市緑地,種組成,鳥類群集,入れ子構造,β 多様性 OYAMA, Yuria, AIZAWA, Akihito and KOBAYASHI, Tatsuaki: Habitat evaluation of birds community at urban green spaces focused on nested structure.Abstract : The purpose of this study is to categorize species composition of urban avifauna community using beta diversity and nestedness analysis at eight districts of Matsudo-city, Chiba, Japan. The eight districts were classified into four types of species composition: high/low of beta diversity x exist/absent of nestedness. Additionally, to figure out the factors that af fect the species composition, we use nMDS plotting. nMDS plotting indicated that the species composition of the study are a extended on the dimension relationing to woods area, water area, farm area and urban area. Every type of the species composition indicated different pattern on the nMDS dimension.
AIZAWA, Akihito, OYAMA, Yuria and KOBAYASHI, Tatsuaki: A hieratical scale approach to evaluate avifauna species richness.Abstract: We used a hieratical scale approach to evaluate avifauna species richness at Matsudo city, Chiba, Japan. Additive partitioning of species diversity and GLM were applied to understand which scale and factors have large contribution for the total species richness of urban avifauna community. As a result, woods area inside of the district scale mainly affected terrestrial birds diversity. On the other hand, the regional geographical factor and local aquatic factor along with grasslands affected water birds. It is considered that conserving woods area at each district scale and creating water areas with grasslands within the local scale are good for conserving urban avifauna richness.
Species composition of aquatic insect in the swimming pool of 32 schools in Tokyo and Chiba prefectures was studied from 2007 to 2008. As a result of TWINSPAN analysis, stands were primarily classified into 2 groups as Tokyo and Chiba. Rhantus pulverosus, Hydaticus grammicus, Ranatra chinensis, and Crocothemis servilia mariannae were not observed at the swimming pools in Tokyo. Major environmental factors of species composition were considered to be the ratio of paddy field in the district and the presence of trees around the pool. The amount of fallen leaves in the pools affected the species population of aquatic insects.
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