Pattern of land mosaics affecting butterfly assemblage at Mt Ikoma, Osaka,Japan

We studied the effects of habitat mosaics on butterfly assemblage on multip le spatial scales: landscape, landscape element, local habitat, and microha bitat, based on the transect counts conducted along a 3.84 km route. The tr ansect route, including 21 local habitats, passed through two distinct area s: 1.65 km of a secondary deciduous Quercus forest and the grove of a shrin e in Hiraoka, and 2.19 km of a mosaic of secondary deciduous Quercus forest , grassland, and farmland in Narukawa. The diversity of the landscape eleme nts and species richness were higher in Narukawa than in Hiraoka; the lands cape mosaic enhanced the species richness in Narukawa. However, the diversi ty indices and specialist species (univoltine tree feeder) were decreased i n this mosaic landscape. The species richness at local habitats was also in creased by the mosaic of microhabitats, such as the herbaceous layer, glade , and mantle in the local habitats, whereas it was decreased by an abundant shrub layer. The ratios of species richness to abundance in the local habi tats were lower than expected based on random sampling from the total of Hi raoka and Narukawa. This means that local assemblages were non-random sampl es from an assemblage on the landscape or regional scale, and were made up by the process of habitat selection of butterfly species in the assemblages on the landscape or regional scale. For conservation of butterfly assembla ges, we recommend that woodlands should be kept without fragmentation, but with glades or small grasslands, and with clearance of the shrub layer alon g the path.