多摩川流域におけるケヤキ枯れ枝に侵入する甲虫類の群集構造

概要

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In order to clarify relative abundance and species diversity of beetle communities within dead woods, the dead branches of Zelkova serrata MAKINO (about 0.4 m^3 in total volume, less than 120 mm in diameter) were collected from 9 sampling sites over the Tama river basin, central Japan, in early spring in 1977. A total of 2337 individuals and 21.4 g dry weight of 80 species belonging to 21 families of Coleoptera were emerged from the dead branches during half a year after the collection. Dead wood feeders, especially cerambycids, were dominant and they occupied 79 percent of the total number of species, 94 percent of individuals, and 98 percent of the total dry weight. Besides, several kinds of predators, fungus feeders, dried carcass feeders and others were also found, but they were minor groups in the community. All samples were divided into 3 regional groups by dendrogram analysis according to the similarity of the species composition as follows : the lower, the middle and the upper basin. Individual density of the samples varied between 3 to 12 inds./10^3 cm^3 and biomass density ranged almost between 40 to 60 mg dry weight/10^3 cm^3. Extreme low species diversity and high density were observed in the lower basin. Species diversity showed a tendency to increase toward the upper basin, and individual density had a tendency to decrease.
東海大学の論文