Communities in infrastructure habitats are species rich but only partly support species associated with semi‐natural grasslands

Abstract

Abstract Biodiversity linked to traditionally managed semi‐natural grasslands is declining, despite conservation efforts. At the same time, the area of novel grassland habitats along linear infrastructure, such as road verges and power line corridors, is increasing and in some regions surpass the area of semi‐natural grasslands. An open question is to what extent these novel grasslands can complement or even replace traditionally managed grasslands as habitat for grassland species. We compared the alpha (species richness) and beta (abundance‐based dissimilarities) diversity of plants, bumblebees and butterflies among semi‐natural pastures, verges of small and big roads, power line corridors and uncultivated field borders nested within 32 landscapes (2 × 2 km squares). Landscapes had either high or low road density and were with or without power line corridors. Across landscapes there was also a gradient in the area of semi‐natural pastures. Alpha diversity of all three species groups was as high in power line corridors and verges of small roads as in semi‐natural pastures, regardless of landscape composition. Although all habitat types shared a large proportion of species, community composition differed among habitats for all three species groups. The beta diversity of plants and butterflies was driven primarily by the replacement of species (turnover), while the beta diversity of bumblebees was driven by a rarer occurrence of certain species in road verges (nestedness). This means that linear infrastructure habitats cannot fully replace the role of semi‐natural grasslands for plant and pollinator diversity. The area of road verges, power line corridors and semi‐natural pastures in the landscape influenced community composition of plants and butterflies, but not the similarity in community composition among habitats within landscapes. Policy implications. Although novel grasslands along linear infrastructures have high numbers of grassland species, they only support a part of the biodiversity found in traditionally managed semi‐natural grasslands. Therefore, protecting and restoring semi‐natural grasslands should continue to be a priority for the conservation of grassland biodiversity. However, especially in landscapes where the area of semi‐natural grasslands is low, road verges and power line corridors can be important habitats for a number of grassland plants and insects and should be managed to promote biodiversity.