Effect of artificial gaps on the butterfly assemblage in urban woods

We examined the effect of gap clearance on butterfly assemblage in an urban park, Expo ’70 commemorial park in Osaka (98.5 ha). Butterflies were recorded in 15 × 15 m quadrat for 10 minuites at six gaps, six plots of woods interior adjacent to the gaps, a vegetable garden, and a turf. Average number of species, S and number of individuals, N were higest at the vegetable garden (S=13, N=55), gap (11.3, 40), woods interior (3.2, 7), turf (2, 6) in this order. Five species, including Papilio bianor were recorded only at gaps, and gap changed the species composition of butterflies and increased the species diversity. Among four gaps where the sky rate was measured, N and S was highest at the gap where the sky rate was higest