Butterfly community structure in fragmented habitats

We analysed effects of habitat fragmentation on the diversity, abundance, a nd life history traits of butterflies on 33 calcareous grasslands. Diversit y of butterflies was positively correlated with habitat area (as was plant diversity), but not with habitat isolation. In contrast to expectations, bu tterfly densities of polyphagous and oligophagous species declined with hab itat area whereas densities of monophagous species increased. The z-values, i.e. the slope of species-area relationships, increased with food plant sp ecialization, from 0.07 in polyphagous, 0.11 in oligophagous, 0.16 in stron gly oligophagous to 0.22 in monophagous species, and were 0.14 in plant spe cies. Significant z-values were not only found for total species richness, based on a sample size adjusted to fragment area (z = 0.12), but also for t he local density of butterfly species richness, based on equal sample size across all habitat fragments (z = 0.06). To our knowledge, this is the firs t study to show differential responses of monophagous, oligophagous and pol yphagous species to area with respect to species richness and population de nsity.