2017 Volume 20 Issue 4 Pages 149-166
Butterfly assemblages were monitored by transect counts at Chiyoda Tree Nursery, Forestry and Forest Products Research Institute, Kasumigaura City, central Japan for ten years (2007–2016). Sixty-seven species and 16,622 individuals of butterflies were recorded. Forty-one to 52 species were recorded each year. Numbers of species and individuals recorded in a year significantly increased in the latter years (2012–2016), especially, densities in May, June, July and August were increased. The most abundant species was Zizeeria maha, followed by Ypthima argus, Lycaena pharaes, Colias erate, Minois dryas and Eurema mandarina. Population densities of 12 species (Y. argus, L. phlaeas, M. dryas, E. mandarina, Neope spp., Argyreus hyperbius, Everes argiades, Polytremis pellucida, Polygonia c-aureum, Neptis sappho, Daimio tethys and Fabriciana adippe) significantly increased in the latter years, but those of three species (Z. maha, Pieris melete and Vanessa cardui) decreased. The Shannon-Wiener function (H′) was 3.283–4.146, the Sympson biodiversity index (1−λ) was 0.776–0.920 and the Pielou measurement of evenness (J′) was 0.594–0.726. These diversity and evenness indices became higher in the later years. Artificial managements, such as the frequency of mowing, may be a major cause of increasing butterfly diversity.
