Authors: Venn, Stephen;

Grasslands are the primary habitat of numerous threatened plant and insect species. As elements of urban green infrastructure, grasslands have a high potential for supporting biodiversity in urban regions. The city of Helsinki has a network of diverse grassland habitats, some of which are managed primarily for biodiversity. I investigated the assemblages of vascular plant and selected insect taxa, of a set of approximately 20 grassland sites in the Helsinki capital region. The aim of this study is to determine the potential value of a set of urban grassland habitats for supporting insect and plant diversity. I also investigate what environmental factors determine the suitability of these sites for different taxa. All of the taxa showed species-area effects, indicating that the small size and isolation of sites are a major challenge. The carabid assemblage is diverse and varies with habitat type, indicating that habitat diversity determines carabid diversity. The bee assemblage is diverse, though dominated by polylectic and ground-nesting species. The butterfly assemblage is poor and included only one meadow species. I conclude that grasslands are valuable for the conservation of urban plant and insect biodiversity but measures should be implemented to enhance habitat provision and reduce habitat isolation.