High-, medium-, and low-dispersal animal taxa communities in fragmented urban grasslands

Urbanized areas are rapidly expanding into a variety of habitats. Urbanization and suburbanization are often associated with changes in biodiversity, which are naturally influenced by biotic interactions and abiotic habitat characteristics. The main cause of changes caused by suburbanization is fragmentation. Its impacts vary between animals with different dispersal abilities. We focused on studying the responses of three taxa with different dispersal abilities: birds as a relatively high-dispersal taxon, medium-dispersal butterflies, and low-dispersal land snails. We studied how biotic factors as well as habitat structural and fragmentation characteristics explain the community composition of the three study taxa in urban grasslands in the city of Pardubice (Czech Republic). Birds were the most species-rich taxon followed by butterflies. Land snails had species-poor grassland communities. Species composition analysis indicated species overlap among the studied taxa. Bird species composition covaried with butterfly species richness and reciprocally. Both taxa were significantly influenced by the amount of woody vegetation within the grassland. Bird community composition was also influenced by fragmentation characteristics, namely the distance to the nearest built-up area. Urban growth most likely leads to changes in the characteristics of animal communities associated with former lowland natural grasslands, deteriorating the communities of low-dispersal land snails while allowing birds that have generally higher dispersal abilities to thrive. Our results show that in assessing the impact of urbanization on biodiversity, attention should also be paid to low-dispersal animal taxa.