Urban dry meadows provide valuable habitat for granivorous and xerophylic carabid beetles

Abstract

Insect and plant assemblages of dry meadow habitats have declined dramatically since the late nineteenth century due to changes in grassland management practices and the resultant overgrowth of these with nitrophilic vegetation in Finland. The Municipality of Helsinki is committed to developing strategies for the maintenance of urban biodiversity, and networks of meadow habitats provide a potential opportunity for conserving declining plant and insect taxa. We showed that urban dry meadows are important habitats for carabid beetle diversity. Dry rocky meadows and managed sheep’s fescue type dry meadows had greater species diversity, more xerophilic species, granivores and autumn-breeding species than matrix grassland habitat. Many open habitat carabid species collected in our study are granivorous and some are known to predate on seeds of abundant generalist plant species. These carabid species may contribute to the maintenance of plant diversity by controlling dominant species. To further enhance urban biodiversity, we recommend (1) the supplementation of dry meadow networks by the appropriate management of existing meadows and potentially supplementary open habitats, (2) the expansion of these by clearing adjacent scrub and secondary woodland (subject to their potential conservation value) and (3) the retention of open vegetation, avoiding its replacement with asphalt. We also recommend the use of habitat creation, such as the construction of dry meadow habitats on landfill hills, traffic noise barriers or green roofs, to further supplement dry meadow networks.