Railway tracks can have great value for butterflies as a new alternative habitat

Abstract Natural and semi-natural habitats are declining. However, little is known of the value of artificial and human-altered habitats for biodiversity maintenance in fragmented landscapes. We hypothesized that railway tracks can have great value for butterflies as an alternative habitat. Using 200-m-long transects, we investigated species richness and two main types of β-diversity, i.e. nestedness and community dispersion, for both butterflies and their nectar plants in eight sites under an expected gradient of habitat quality – meadows, railway tracks, forest clearings and degraded meadows. Railway tracks and meadows had higher butterfly species richness than forest clearings and degraded meadow. Butterfly species distribution among sites was strongly related to the gradient of habitat quality that was measured as nectar plant composition. Railway tracks contained the widest pool of butterflies with species of various biotopes as well as a wide pool of nectar plants at a nested subset pattern of β-diversity. However, the pattern of community dispersion was opposite to what had been expected. Meadows and railway tracks, being more heterogeneous sites in terms of composition of nectar plants, supported slightly more homogeneous butterfly communities. This suggests that habitats of low quality, i.e. forest clearings and degraded meadows, have less-stable butterfly communities. We concluded that railway tracks located on sun-warmed embankments containing a reach pool of nectar plants could enable multi-species communities to persist in an environment of good suitability. Conservation managers should therefore focus on enhancing the quality of railway tracks and their vicinity through the preservation of a high abundance of various flowering plants.